src/libsyntax/parse/parser.rs

   1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 pub use self::PathParsingMode::*;
  12
  13 use abi;
  14 use ast::BareFnTy;
  15 use ast::{RegionTyParamBound, TraitTyParamBound, TraitBoundModifier};
  16 use ast::{Public, Unsafety};
  17 use ast::{Mod, BiAdd, Arg, Arm, Attribute, BindingMode};
  18 use ast::{BiBitAnd, BiBitOr, BiBitXor, BiRem, BiLt, Block};
  19 use ast::{BlockCheckMode, CaptureByRef, CaptureByValue, CaptureClause};
  20 use ast::{Constness, ConstTraitItem, Crate, CrateConfig};
  21 use ast::{Decl, DeclItem, DeclLocal, DefaultBlock, DefaultReturn};
  22 use ast::{UnDeref, BiDiv, EMPTY_CTXT, EnumDef, ExplicitSelf};
  23 use ast::{Expr, Expr_, ExprAddrOf, ExprMatch, ExprAgain};
  24 use ast::{ExprAssign, ExprAssignOp, ExprBinary, ExprBlock, ExprBox};
  25 use ast::{ExprBreak, ExprCall, ExprCast, ExprInPlace};
  26 use ast::{ExprField, ExprTupField, ExprClosure, ExprIf, ExprIfLet, ExprIndex};
  27 use ast::{ExprLit, ExprLoop, ExprMac, ExprRange};
  28 use ast::{ExprMethodCall, ExprParen, ExprPath};
  29 use ast::{ExprRepeat, ExprRet, ExprStruct, ExprTup, ExprType, ExprUnary};
  30 use ast::{ExprVec, ExprWhile, ExprWhileLet, ExprForLoop, Field, FnDecl};
  31 use ast::{ForeignItem, ForeignItemStatic, ForeignItemFn, FunctionRetTy};
  32 use ast::{Ident, Inherited, ImplItem, Item, Item_, ItemStatic};
  33 use ast::{ItemEnum, ItemFn, ItemForeignMod, ItemImpl, ItemConst};
  34 use ast::{ItemMac, ItemMod, ItemStruct, ItemTrait, ItemTy, ItemDefaultImpl};
  35 use ast::{ItemExternCrate, ItemUse};
  36 use ast::{Lit, Lit_};
  37 use ast::{LitBool, LitChar, LitByte, LitByteStr};
  38 use ast::{LitStr, LitInt, Local};
  39 use ast::{MacStmtWithBraces, MacStmtWithSemicolon, MacStmtWithoutBraces};
  40 use ast::{MutImmutable, MutMutable, Mac_};
  41 use ast::{MutTy, BiMul, Mutability};
  42 use ast::{NamedField, UnNeg, NoReturn, UnNot};
  43 use ast::{Pat, PatBox, PatEnum, PatIdent, PatLit, PatQPath, PatMac, PatRange};
  44 use ast::{PatRegion, PatStruct, PatTup, PatVec, PatWild};
  45 use ast::{PolyTraitRef, QSelf};
  46 use ast::{Return, BiShl, BiShr, Stmt, StmtDecl};
  47 use ast::{StmtExpr, StmtSemi, StmtMac, VariantData, StructField};
  48 use ast::{BiSub, StrStyle};
  49 use ast::{SelfExplicit, SelfRegion, SelfStatic, SelfValue};
  50 use ast::{Delimited, SequenceRepetition, TokenTree, TraitItem, TraitRef};
  51 use ast::{Ty, Ty_, TypeBinding, TyMac};
  52 use ast::{TyFixedLengthVec, TyBareFn, TyTypeof, TyInfer};
  53 use ast::{TyParam, TyParamBounds, TyParen, TyPath, TyPtr};
  54 use ast::{TyRptr, TyTup, TyU32, TyVec};
  55 use ast::TypeTraitItem;
  56 use ast::{UnnamedField, UnsafeBlock};
  57 use ast::{ViewPath, ViewPathGlob, ViewPathList, ViewPathSimple};
  58 use ast::{Visibility, WhereClause};
  59 use attr::{ThinAttributes, ThinAttributesExt, AttributesExt};
  60 use ast;
  61 use ast_util::{self, ident_to_path};
  62 use codemap::{self, Span, BytePos, Spanned, spanned, mk_sp, CodeMap};
  63 use errors::{self, DiagnosticBuilder};
  64 use ext::tt::macro_parser;
  65 use parse;
  66 use parse::classify;
  67 use parse::common::{SeqSep, seq_sep_none, seq_sep_trailing_allowed};
  68 use parse::lexer::{Reader, TokenAndSpan};
  69 use parse::obsolete::{ParserObsoleteMethods, ObsoleteSyntax};
  70 use parse::token::{self, intern, MatchNt, SubstNt, SpecialVarNt, InternedString};
  71 use parse::token::{keywords, special_idents, SpecialMacroVar};
  72 use parse::{new_sub_parser_from_file, ParseSess};
  73 use util::parser::{AssocOp, Fixity};
  74 use print::pprust;
  75 use ptr::P;
  76 use parse::PResult;
  77
  78 use std::collections::HashSet;
  79 use std::io::prelude::*;
  80 use std::mem;
  81 use std::path::{Path, PathBuf};
  82 use std::rc::Rc;
  83 use std::slice;
  84
  85 bitflags! {
  86     flags Restrictions: u8 {
  87         const RESTRICTION_STMT_EXPR         = 1 << 0,
  88         const RESTRICTION_NO_STRUCT_LITERAL = 1 << 1,
  89     }
  90 }
  91
  92 type ItemInfo = (Ident, Item_, Option<Vec<Attribute> >);
  93
  94 /// How to parse a path. There are four different kinds of paths, all of which
  95 /// are parsed somewhat differently.
  96 #[derive(Copy, Clone, PartialEq)]
  97 pub enum PathParsingMode {
  98     /// A path with no type parameters; e.g. `foo::bar::Baz`
  99     NoTypesAllowed,
 100     /// A path with a lifetime and type parameters, with no double colons
 101     /// before the type parameters; e.g. `foo::bar<'a>::Baz<T>`
 102     LifetimeAndTypesWithoutColons,
 103     /// A path with a lifetime and type parameters with double colons before
 104     /// the type parameters; e.g. `foo::bar::<'a>::Baz::<T>`
 105     LifetimeAndTypesWithColons,
 106 }
 107
 108 /// How to parse a bound, whether to allow bound modifiers such as `?`.
 109 #[derive(Copy, Clone, PartialEq)]
 110 pub enum BoundParsingMode {
 111     Bare,
 112     Modified,
 113 }
 114
 115 /// `pub` should be parsed in struct fields and not parsed in variant fields
 116 #[derive(Clone, Copy, PartialEq)]
 117 pub enum ParsePub {
 118     Yes,
 119     No,
 120 }
 121
 122 /// Possibly accept an `token::Interpolated` expression (a pre-parsed expression
 123 /// dropped into the token stream, which happens while parsing the result of
 124 /// macro expansion). Placement of these is not as complex as I feared it would
 125 /// be. The important thing is to make sure that lookahead doesn't balk at
 126 /// `token::Interpolated` tokens.
 127 macro_rules! maybe_whole_expr {
 128     ($p:expr) => (
 129         {
 130             let found = match $p.token {
 131                 token::Interpolated(token::NtExpr(ref e)) => {
 132                     Some((*e).clone())
 133                 }
 134                 token::Interpolated(token::NtPath(_)) => {
 135                     // FIXME: The following avoids an issue with lexical borrowck scopes,
 136                     // but the clone is unfortunate.
 137                     let pt = match $p.token {
 138                         token::Interpolated(token::NtPath(ref pt)) => (**pt).clone(),
 139                         _ => unreachable!()
 140                     };
 141                     let span = $p.span;
 142                     Some($p.mk_expr(span.lo, span.hi, ExprPath(None, pt), None))
 143                 }
 144                 token::Interpolated(token::NtBlock(_)) => {
 145                     // FIXME: The following avoids an issue with lexical borrowck scopes,
 146                     // but the clone is unfortunate.
 147                     let b = match $p.token {
 148                         token::Interpolated(token::NtBlock(ref b)) => (*b).clone(),
 149                         _ => unreachable!()
 150                     };
 151                     let span = $p.span;
 152                     Some($p.mk_expr(span.lo, span.hi, ExprBlock(b), None))
 153                 }
 154                 _ => None
 155             };
 156             match found {
 157                 Some(e) => {
 158                     $p.bump();
 159                     return Ok(e);
 160                 }
 161                 None => ()
 162             }
 163         }
 164     )
 165 }
 166
 167 /// As maybe_whole_expr, but for things other than expressions
 168 macro_rules! maybe_whole {
 169     ($p:expr, $constructor:ident) => (
 170         {
 171             let found = match ($p).token {
 172                 token::Interpolated(token::$constructor(_)) => {
 173                     Some(($p).bump_and_get())
 174                 }
 175                 _ => None
 176             };
 177             if let Some(token::Interpolated(token::$constructor(x))) = found {
 178                 return Ok(x.clone());
 179             }
 180         }
 181     );
 182     (no_clone $p:expr, $constructor:ident) => (
 183         {
 184             let found = match ($p).token {
 185                 token::Interpolated(token::$constructor(_)) => {
 186                     Some(($p).bump_and_get())
 187                 }
 188                 _ => None
 189             };
 190             if let Some(token::Interpolated(token::$constructor(x))) = found {
 191                 return Ok(x);
 192             }
 193         }
 194     );
 195     (deref $p:expr, $constructor:ident) => (
 196         {
 197             let found = match ($p).token {
 198                 token::Interpolated(token::$constructor(_)) => {
 199                     Some(($p).bump_and_get())
 200                 }
 201                 _ => None
 202             };
 203             if let Some(token::Interpolated(token::$constructor(x))) = found {
 204                 return Ok((*x).clone());
 205             }
 206         }
 207     );
 208     (Some deref $p:expr, $constructor:ident) => (
 209         {
 210             let found = match ($p).token {
 211                 token::Interpolated(token::$constructor(_)) => {
 212                     Some(($p).bump_and_get())
 213                 }
 214                 _ => None
 215             };
 216             if let Some(token::Interpolated(token::$constructor(x))) = found {
 217                 return Ok(Some((*x).clone()));
 218             }
 219         }
 220     );
 221     (pair_empty $p:expr, $constructor:ident) => (
 222         {
 223             let found = match ($p).token {
 224                 token::Interpolated(token::$constructor(_)) => {
 225                     Some(($p).bump_and_get())
 226                 }
 227                 _ => None
 228             };
 229             if let Some(token::Interpolated(token::$constructor(x))) = found {
 230                 return Ok((Vec::new(), x));
 231             }
 232         }
 233     )
 234 }
 235
 236 fn maybe_append(mut lhs: Vec<Attribute>, rhs: Option<Vec<Attribute>>)
 237                 -> Vec<Attribute> {
 238     if let Some(ref attrs) = rhs {
 239         lhs.extend(attrs.iter().cloned())
 240     }
 241     lhs
 242 }
 243
 244 /* ident is handled by common.rs */
 245
 246 pub struct Parser<'a> {
 247     pub sess: &'a ParseSess,
 248     /// the current token:
 249     pub token: token::Token,
 250     /// the span of the current token:
 251     pub span: Span,
 252     /// the span of the prior token:
 253     pub last_span: Span,
 254     pub cfg: CrateConfig,
 255     /// the previous token or None (only stashed sometimes).
 256     pub last_token: Option<Box<token::Token>>,
 257     last_token_interpolated: bool,
 258     pub buffer: [TokenAndSpan; 4],
 259     pub buffer_start: isize,
 260     pub buffer_end: isize,
 261     pub tokens_consumed: usize,
 262     pub restrictions: Restrictions,
 263     pub quote_depth: usize, // not (yet) related to the quasiquoter
 264     pub reader: Box<Reader+'a>,
 265     pub interner: Rc<token::IdentInterner>,
 266     /// The set of seen errors about obsolete syntax. Used to suppress
 267     /// extra detail when the same error is seen twice
 268     pub obsolete_set: HashSet<ObsoleteSyntax>,
 269     /// Used to determine the path to externally loaded source files
 270     pub mod_path_stack: Vec<InternedString>,
 271     /// Stack of spans of open delimiters. Used for error message.
 272     pub open_braces: Vec<Span>,
 273     /// Flag if this parser "owns" the directory that it is currently parsing
 274     /// in. This will affect how nested files are looked up.
 275     pub owns_directory: bool,
 276     /// Name of the root module this parser originated from. If `None`, then the
 277     /// name is not known. This does not change while the parser is descending
 278     /// into modules, and sub-parsers have new values for this name.
 279     pub root_module_name: Option<String>,
 280     pub expected_tokens: Vec<TokenType>,
 281 }
 282
 283 #[derive(PartialEq, Eq, Clone)]
 284 pub enum TokenType {
 285     Token(token::Token),
 286     Keyword(keywords::Keyword),
 287     Operator,
 288 }
 289
 290 impl TokenType {
 291     fn to_string(&self) -> String {
 292         match *self {
 293             TokenType::Token(ref t) => format!("`{}`", Parser::token_to_string(t)),
 294             TokenType::Operator => "an operator".to_string(),
 295             TokenType::Keyword(kw) => format!("`{}`", kw.to_name()),
 296         }
 297     }
 298 }
 299
 300 fn is_plain_ident_or_underscore(t: &token::Token) -> bool {
 301     t.is_plain_ident() || *t == token::Underscore
 302 }
 303
 304 /// Information about the path to a module.
 305 pub struct ModulePath {
 306     pub name: String,
 307     pub path_exists: bool,
 308     pub result: Result<ModulePathSuccess, ModulePathError>,
 309 }
 310
 311 pub struct ModulePathSuccess {
 312     pub path: ::std::path::PathBuf,
 313     pub owns_directory: bool,
 314 }
 315
 316 pub struct ModulePathError {
 317     pub err_msg: String,
 318     pub help_msg: String,
 319 }
 320
 321 pub enum LhsExpr {
 322     NotYetParsed,
 323     AttributesParsed(ThinAttributes),
 324     AlreadyParsed(P<Expr>),
 325 }
 326
 327 impl From<Option<ThinAttributes>> for LhsExpr {
 328     fn from(o: Option<ThinAttributes>) -> Self {
 329         if let Some(attrs) = o {
 330             LhsExpr::AttributesParsed(attrs)
 331         } else {
 332             LhsExpr::NotYetParsed
 333         }
 334     }
 335 }
 336
 337 impl From<P<Expr>> for LhsExpr {
 338     fn from(expr: P<Expr>) -> Self {
 339         LhsExpr::AlreadyParsed(expr)
 340     }
 341 }
 342
 343 impl<'a> Parser<'a> {
 344     pub fn new(sess: &'a ParseSess,
 345                cfg: ast::CrateConfig,
 346                mut rdr: Box<Reader+'a>)
 347                -> Parser<'a>
 348     {
 349         let tok0 = rdr.real_token();
 350         let span = tok0.sp;
 351         let placeholder = TokenAndSpan {
 352             tok: token::Underscore,
 353             sp: span,
 354         };
 355
 356         Parser {
 357             reader: rdr,
 358             interner: token::get_ident_interner(),
 359             sess: sess,
 360             cfg: cfg,
 361             token: tok0.tok,
 362             span: span,
 363             last_span: span,
 364             last_token: None,
 365             last_token_interpolated: false,
 366             buffer: [
 367                 placeholder.clone(),
 368                 placeholder.clone(),
 369                 placeholder.clone(),
 370                 placeholder.clone(),
 371             ],
 372             buffer_start: 0,
 373             buffer_end: 0,
 374             tokens_consumed: 0,
 375             restrictions: Restrictions::empty(),
 376             quote_depth: 0,
 377             obsolete_set: HashSet::new(),
 378             mod_path_stack: Vec::new(),
 379             open_braces: Vec::new(),
 380             owns_directory: true,
 381             root_module_name: None,
 382             expected_tokens: Vec::new(),
 383         }
 384     }
 385
 386     /// Convert a token to a string using self's reader
 387     pub fn token_to_string(token: &token::Token) -> String {
 388         pprust::token_to_string(token)
 389     }
 390
 391     /// Convert the current token to a string using self's reader
 392     pub fn this_token_to_string(&self) -> String {
 393         Parser::token_to_string(&self.token)
 394     }
 395
 396     pub fn unexpected_last<T>(&self, t: &token::Token) -> PResult<'a, T> {
 397         let token_str = Parser::token_to_string(t);
 398         let last_span = self.last_span;
 399         Err(self.span_fatal(last_span, &format!("unexpected token: `{}`", token_str)))
 400     }
 401
 402     pub fn unexpected<T>(&mut self) -> PResult<'a, T> {
 403         match self.expect_one_of(&[], &[]) {
 404             Err(e) => Err(e),
 405             Ok(_) => unreachable!(),
 406         }
 407     }
 408
 409     /// Expect and consume the token t. Signal an error if
 410     /// the next token is not t.
 411     pub fn expect(&mut self, t: &token::Token) -> PResult<'a,  ()> {
 412         if self.expected_tokens.is_empty() {
 413             if self.token == *t {
 414                 self.bump();
 415                 Ok(())
 416             } else {
 417                 let token_str = Parser::token_to_string(t);
 418                 let this_token_str = self.this_token_to_string();
 419                 Err(self.fatal(&format!("expected `{}`, found `{}`",
 420                                    token_str,
 421                                    this_token_str)))
 422             }
 423         } else {
 424             self.expect_one_of(unsafe { slice::from_raw_parts(t, 1) }, &[])
 425         }
 426     }
 427
 428     /// Expect next token to be edible or inedible token.  If edible,
 429     /// then consume it; if inedible, then return without consuming
 430     /// anything.  Signal a fatal error if next token is unexpected.
 431     pub fn expect_one_of(&mut self,
 432                          edible: &[token::Token],
 433                          inedible: &[token::Token]) -> PResult<'a,  ()>{
 434         fn tokens_to_string(tokens: &[TokenType]) -> String {
 435             let mut i = tokens.iter();
 436             // This might be a sign we need a connect method on Iterator.
 437             let b = i.next()
 438                      .map_or("".to_string(), |t| t.to_string());
 439             i.enumerate().fold(b, |mut b, (i, ref a)| {
 440                 if tokens.len() > 2 && i == tokens.len() - 2 {
 441                     b.push_str(", or ");
 442                 } else if tokens.len() == 2 && i == tokens.len() - 2 {
 443                     b.push_str(" or ");
 444                 } else {
 445                     b.push_str(", ");
 446                 }
 447                 b.push_str(&*a.to_string());
 448                 b
 449             })
 450         }
 451         if edible.contains(&self.token) {
 452             self.bump();
 453             Ok(())
 454         } else if inedible.contains(&self.token) {
 455             // leave it in the input
 456             Ok(())
 457         } else {
 458             let mut expected = edible.iter()
 459                 .map(|x| TokenType::Token(x.clone()))
 460                 .chain(inedible.iter().map(|x| TokenType::Token(x.clone())))
 461                 .chain(self.expected_tokens.iter().cloned())
 462                 .collect::<Vec<_>>();
 463             expected.sort_by(|a, b| a.to_string().cmp(&b.to_string()));
 464             expected.dedup();
 465             let expect = tokens_to_string(&expected[..]);
 466             let actual = self.this_token_to_string();
 467             Err(self.fatal(
 468                 &(if expected.len() > 1 {
 469                     (format!("expected one of {}, found `{}`",
 470                              expect,
 471                              actual))
 472                 } else if expected.is_empty() {
 473                     (format!("unexpected token: `{}`",
 474                              actual))
 475                 } else {
 476                     (format!("expected {}, found `{}`",
 477                              expect,
 478                              actual))
 479                 })[..]
 480             ))
 481         }
 482     }
 483
 484     /// Check for erroneous `ident { }`; if matches, signal error and
 485     /// recover (without consuming any expected input token).  Returns
 486     /// true if and only if input was consumed for recovery.
 487     pub fn check_for_erroneous_unit_struct_expecting(&mut self,
 488                                                      expected: &[token::Token])
 489                                                      -> bool {
 490         if self.token == token::OpenDelim(token::Brace)
 491             && expected.iter().all(|t| *t != token::OpenDelim(token::Brace))
 492             && self.look_ahead(1, |t| *t == token::CloseDelim(token::Brace)) {
 493             // matched; signal non-fatal error and recover.
 494             let span = self.span;
 495             self.span_err(span, "unit-like struct construction is written with no trailing `{ }`");
 496             self.eat(&token::OpenDelim(token::Brace));
 497             self.eat(&token::CloseDelim(token::Brace));
 498             true
 499         } else {
 500             false
 501         }
 502     }
 503
 504     /// Commit to parsing a complete expression `e` expected to be
 505     /// followed by some token from the set edible + inedible.  Recover
 506     /// from anticipated input errors, discarding erroneous characters.
 507     pub fn commit_expr(&mut self, e: &Expr, edible: &[token::Token],
 508                        inedible: &[token::Token]) -> PResult<'a, ()> {
 509         debug!("commit_expr {:?}", e);
 510         if let ExprPath(..) = e.node {
 511             // might be unit-struct construction; check for recoverableinput error.
 512             let expected = edible.iter()
 513                 .cloned()
 514                 .chain(inedible.iter().cloned())
 515                 .collect::<Vec<_>>();
 516             self.check_for_erroneous_unit_struct_expecting(&expected[..]);
 517         }
 518         self.expect_one_of(edible, inedible)
 519     }
 520
 521     pub fn commit_expr_expecting(&mut self, e: &Expr, edible: token::Token) -> PResult<'a, ()> {
 522         self.commit_expr(e, &[edible], &[])
 523     }
 524
 525     /// Commit to parsing a complete statement `s`, which expects to be
 526     /// followed by some token from the set edible + inedible.  Check
 527     /// for recoverable input errors, discarding erroneous characters.
 528     pub fn commit_stmt(&mut self, edible: &[token::Token],
 529                        inedible: &[token::Token]) -> PResult<'a, ()> {
 530         if self.last_token
 531                .as_ref()
 532                .map_or(false, |t| t.is_ident() || t.is_path()) {
 533             let expected = edible.iter()
 534                 .cloned()
 535                 .chain(inedible.iter().cloned())
 536                 .collect::<Vec<_>>();
 537             self.check_for_erroneous_unit_struct_expecting(&expected);
 538         }
 539         self.expect_one_of(edible, inedible)
 540     }
 541
 542     pub fn commit_stmt_expecting(&mut self, edible: token::Token) -> PResult<'a, ()> {
 543         self.commit_stmt(&[edible], &[])
 544     }
 545
 546     /// returns the span of expr, if it was not interpolated or the span of the interpolated token
 547     fn interpolated_or_expr_span(&self,
 548                                  expr: PResult<'a, P<Expr>>)
 549                                  -> PResult<'a, (Span, P<Expr>)> {
 550         expr.map(|e| {
 551             if self.last_token_interpolated {
 552                 (self.last_span, e)
 553             } else {
 554                 (e.span, e)
 555             }
 556         })
 557     }
 558
 559     pub fn parse_ident(&mut self) -> PResult<'a, ast::Ident> {
 560         self.check_strict_keywords();
 561         self.check_reserved_keywords();
 562         match self.token {
 563             token::Ident(i, _) => {
 564                 self.bump();
 565                 Ok(i)
 566             }
 567             token::Interpolated(token::NtIdent(..)) => {
 568                 self.bug("ident interpolation not converted to real token");
 569             }
 570             _ => {
 571                 let token_str = self.this_token_to_string();
 572                 Err(self.fatal(&format!("expected ident, found `{}`",
 573                                     token_str)))
 574             }
 575         }
 576     }
 577
 578     pub fn parse_ident_or_self_type(&mut self) -> PResult<'a, ast::Ident> {
 579         if self.is_self_type_ident() {
 580             self.expect_self_type_ident()
 581         } else {
 582             self.parse_ident()
 583         }
 584     }
 585
 586     pub fn parse_path_list_item(&mut self) -> PResult<'a, ast::PathListItem> {
 587         let lo = self.span.lo;
 588         let node = if self.eat_keyword(keywords::SelfValue) {
 589             let rename = try!(self.parse_rename());
 590             ast::PathListMod { id: ast::DUMMY_NODE_ID, rename: rename }
 591         } else {
 592             let ident = try!(self.parse_ident());
 593             let rename = try!(self.parse_rename());
 594             ast::PathListIdent { name: ident, rename: rename, id: ast::DUMMY_NODE_ID }
 595         };
 596         let hi = self.last_span.hi;
 597         Ok(spanned(lo, hi, node))
 598     }
 599
 600     /// Check if the next token is `tok`, and return `true` if so.
 601     ///
 602     /// This method is will automatically add `tok` to `expected_tokens` if `tok` is not
 603     /// encountered.
 604     pub fn check(&mut self, tok: &token::Token) -> bool {
 605         let is_present = self.token == *tok;
 606         if !is_present { self.expected_tokens.push(TokenType::Token(tok.clone())); }
 607         is_present
 608     }
 609
 610     /// Consume token 'tok' if it exists. Returns true if the given
 611     /// token was present, false otherwise.
 612     pub fn eat(&mut self, tok: &token::Token) -> bool {
 613         let is_present = self.check(tok);
 614         if is_present { self.bump() }
 615         is_present
 616     }
 617
 618     pub fn check_keyword(&mut self, kw: keywords::Keyword) -> bool {
 619         self.expected_tokens.push(TokenType::Keyword(kw));
 620         self.token.is_keyword(kw)
 621     }
 622
 623     /// If the next token is the given keyword, eat it and return
 624     /// true. Otherwise, return false.
 625     pub fn eat_keyword(&mut self, kw: keywords::Keyword) -> bool {
 626         if self.check_keyword(kw) {
 627             self.bump();
 628             true
 629         } else {
 630             false
 631         }
 632     }
 633
 634     pub fn eat_keyword_noexpect(&mut self, kw: keywords::Keyword) -> bool {
 635         if self.token.is_keyword(kw) {
 636             self.bump();
 637             true
 638         } else {
 639             false
 640         }
 641     }
 642
 643     /// If the given word is not a keyword, signal an error.
 644     /// If the next token is not the given word, signal an error.
 645     /// Otherwise, eat it.
 646     pub fn expect_keyword(&mut self, kw: keywords::Keyword) -> PResult<'a, ()> {
 647         if !self.eat_keyword(kw) {
 648             self.unexpected()
 649         } else {
 650             Ok(())
 651         }
 652     }
 653
 654     /// Signal an error if the given string is a strict keyword
 655     pub fn check_strict_keywords(&mut self) {
 656         if self.token.is_strict_keyword() {
 657             let token_str = self.this_token_to_string();
 658             let span = self.span;
 659             self.span_err(span,
 660                           &format!("expected identifier, found keyword `{}`",
 661                                   token_str));
 662         }
 663     }
 664
 665     /// Signal an error if the current token is a reserved keyword
 666     pub fn check_reserved_keywords(&mut self) {
 667         if self.token.is_reserved_keyword() {
 668             let token_str = self.this_token_to_string();
 669             self.fatal(&format!("`{}` is a reserved keyword", token_str)).emit()
 670         }
 671     }
 672
 673     /// Expect and consume an `&`. If `&&` is seen, replace it with a single
 674     /// `&` and continue. If an `&` is not seen, signal an error.
 675     fn expect_and(&mut self) -> PResult<'a, ()> {
 676         self.expected_tokens.push(TokenType::Token(token::BinOp(token::And)));
 677         match self.token {
 678             token::BinOp(token::And) => {
 679                 self.bump();
 680                 Ok(())
 681             }
 682             token::AndAnd => {
 683                 let span = self.span;
 684                 let lo = span.lo + BytePos(1);
 685                 Ok(self.replace_token(token::BinOp(token::And), lo, span.hi))
 686             }
 687             _ => self.unexpected()
 688         }
 689     }
 690
 691     pub fn expect_no_suffix(&self, sp: Span, kind: &str, suffix: Option<ast::Name>) {
 692         match suffix {
 693             None => {/* everything ok */}
 694             Some(suf) => {
 695                 let text = suf.as_str();
 696                 if text.is_empty() {
 697                     self.span_bug(sp, "found empty literal suffix in Some")
 698                 }
 699                 self.span_err(sp, &*format!("{} with a suffix is invalid", kind));
 700             }
 701         }
 702     }
 703
 704
 705     /// Attempt to consume a `<`. If `<<` is seen, replace it with a single
 706     /// `<` and continue. If a `<` is not seen, return false.
 707     ///
 708     /// This is meant to be used when parsing generics on a path to get the
 709     /// starting token.
 710     fn eat_lt(&mut self) -> bool {
 711         self.expected_tokens.push(TokenType::Token(token::Lt));
 712         match self.token {
 713             token::Lt => {
 714                 self.bump();
 715                 true
 716             }
 717             token::BinOp(token::Shl) => {
 718                 let span = self.span;
 719                 let lo = span.lo + BytePos(1);
 720                 self.replace_token(token::Lt, lo, span.hi);
 721                 true
 722             }
 723             _ => false,
 724         }
 725     }
 726
 727     fn expect_lt(&mut self) -> PResult<'a, ()> {
 728         if !self.eat_lt() {
 729             self.unexpected()
 730         } else {
 731             Ok(())
 732         }
 733     }
 734
 735     /// Expect and consume a GT. if a >> is seen, replace it
 736     /// with a single > and continue. If a GT is not seen,
 737     /// signal an error.
 738     pub fn expect_gt(&mut self) -> PResult<'a, ()> {
 739         self.expected_tokens.push(TokenType::Token(token::Gt));
 740         match self.token {
 741             token::Gt => {
 742                 self.bump();
 743                 Ok(())
 744             }
 745             token::BinOp(token::Shr) => {
 746                 let span = self.span;
 747                 let lo = span.lo + BytePos(1);
 748                 Ok(self.replace_token(token::Gt, lo, span.hi))
 749             }
 750             token::BinOpEq(token::Shr) => {
 751                 let span = self.span;
 752                 let lo = span.lo + BytePos(1);
 753                 Ok(self.replace_token(token::Ge, lo, span.hi))
 754             }
 755             token::Ge => {
 756                 let span = self.span;
 757                 let lo = span.lo + BytePos(1);
 758                 Ok(self.replace_token(token::Eq, lo, span.hi))
 759             }
 760             _ => {
 761                 let gt_str = Parser::token_to_string(&token::Gt);
 762                 let this_token_str = self.this_token_to_string();
 763                 Err(self.fatal(&format!("expected `{}`, found `{}`",
 764                                    gt_str,
 765                                    this_token_str)))
 766             }
 767         }
 768     }
 769
 770     pub fn parse_seq_to_before_gt_or_return<T, F>(&mut self,
 771                                                   sep: Option<token::Token>,
 772                                                   mut f: F)
 773                                                   -> PResult<'a, (P<[T]>, bool)>
 774         where F: FnMut(&mut Parser<'a>) -> PResult<'a, Option<T>>,
 775     {
 776         let mut v = Vec::new();
 777         // This loop works by alternating back and forth between parsing types
 778         // and commas.  For example, given a string `A, B,>`, the parser would
 779         // first parse `A`, then a comma, then `B`, then a comma. After that it
 780         // would encounter a `>` and stop. This lets the parser handle trailing
 781         // commas in generic parameters, because it can stop either after
 782         // parsing a type or after parsing a comma.
 783         for i in 0.. {
 784             if self.check(&token::Gt)
 785                 || self.token == token::BinOp(token::Shr)
 786                 || self.token == token::Ge
 787                 || self.token == token::BinOpEq(token::Shr) {
 788                 break;
 789             }
 790
 791             if i % 2 == 0 {
 792                 match try!(f(self)) {
 793                     Some(result) => v.push(result),
 794                     None => return Ok((P::from_vec(v), true))
 795                 }
 796             } else {
 797                 if let Some(t) = sep.as_ref() {
 798                     try!(self.expect(t));
 799                 }
 800
 801             }
 802         }
 803         return Ok((P::from_vec(v), false));
 804     }
 805
 806     /// Parse a sequence bracketed by '<' and '>', stopping
 807     /// before the '>'.
 808     pub fn parse_seq_to_before_gt<T, F>(&mut self,
 809                                         sep: Option<token::Token>,
 810                                         mut f: F)
 811                                         -> PResult<'a, P<[T]>> where
 812         F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
 813     {
 814         let (result, returned) = try!(self.parse_seq_to_before_gt_or_return(sep,
 815                                                     |p| Ok(Some(try!(f(p))))));
 816         assert!(!returned);
 817         return Ok(result);
 818     }
 819
 820     pub fn parse_seq_to_gt<T, F>(&mut self,
 821                                  sep: Option<token::Token>,
 822                                  f: F)
 823                                  -> PResult<'a, P<[T]>> where
 824         F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
 825     {
 826         let v = try!(self.parse_seq_to_before_gt(sep, f));
 827         try!(self.expect_gt());
 828         return Ok(v);
 829     }
 830
 831     pub fn parse_seq_to_gt_or_return<T, F>(&mut self,
 832                                            sep: Option<token::Token>,
 833                                            f: F)
 834                                            -> PResult<'a, (P<[T]>, bool)> where
 835         F: FnMut(&mut Parser<'a>) -> PResult<'a, Option<T>>,
 836     {
 837         let (v, returned) = try!(self.parse_seq_to_before_gt_or_return(sep, f));
 838         if !returned {
 839             try!(self.expect_gt());
 840         }
 841         return Ok((v, returned));
 842     }
 843
 844     /// Parse a sequence, including the closing delimiter. The function
 845     /// f must consume tokens until reaching the next separator or
 846     /// closing bracket.
 847     pub fn parse_seq_to_end<T, F>(&mut self,
 848                                   ket: &token::Token,
 849                                   sep: SeqSep,
 850                                   f: F)
 851                                   -> PResult<'a, Vec<T>> where
 852         F: FnMut(&mut Parser<'a>) -> PResult<'a,  T>,
 853     {
 854         let val = try!(self.parse_seq_to_before_end(ket, sep, f));
 855         self.bump();
 856         Ok(val)
 857     }
 858
 859     /// Parse a sequence, not including the closing delimiter. The function
 860     /// f must consume tokens until reaching the next separator or
 861     /// closing bracket.
 862     pub fn parse_seq_to_before_end<T, F>(&mut self,
 863                                          ket: &token::Token,
 864                                          sep: SeqSep,
 865                                          mut f: F)
 866                                          -> PResult<'a, Vec<T>> where
 867         F: FnMut(&mut Parser<'a>) -> PResult<'a,  T>,
 868     {
 869         let mut first: bool = true;
 870         let mut v = vec!();
 871         while self.token != *ket {
 872             match sep.sep {
 873               Some(ref t) => {
 874                 if first { first = false; }
 875                 else { try!(self.expect(t)); }
 876               }
 877               _ => ()
 878             }
 879             if sep.trailing_sep_allowed && self.check(ket) { break; }
 880             v.push(try!(f(self)));
 881         }
 882         return Ok(v);
 883     }
 884
 885     /// Parse a sequence, including the closing delimiter. The function
 886     /// f must consume tokens until reaching the next separator or
 887     /// closing bracket.
 888     pub fn parse_unspanned_seq<T, F>(&mut self,
 889                                      bra: &token::Token,
 890                                      ket: &token::Token,
 891                                      sep: SeqSep,
 892                                      f: F)
 893                                      -> PResult<'a, Vec<T>> where
 894         F: FnMut(&mut Parser<'a>) -> PResult<'a,  T>,
 895     {
 896         try!(self.expect(bra));
 897         let result = try!(self.parse_seq_to_before_end(ket, sep, f));
 898         self.bump();
 899         Ok(result)
 900     }
 901
 902     /// Parse a sequence parameter of enum variant. For consistency purposes,
 903     /// these should not be empty.
 904     pub fn parse_enum_variant_seq<T, F>(&mut self,
 905                                         bra: &token::Token,
 906                                         ket: &token::Token,
 907                                         sep: SeqSep,
 908                                         f: F)
 909                                         -> PResult<'a, Vec<T>> where
 910         F: FnMut(&mut Parser<'a>) -> PResult<'a,  T>,
 911     {
 912         let result = try!(self.parse_unspanned_seq(bra, ket, sep, f));
 913         if result.is_empty() {
 914             let last_span = self.last_span;
 915             self.span_err(last_span,
 916             "nullary enum variants are written with no trailing `( )`");
 917         }
 918         Ok(result)
 919     }
 920
 921     // NB: Do not use this function unless you actually plan to place the
 922     // spanned list in the AST.
 923     pub fn parse_seq<T, F>(&mut self,
 924                            bra: &token::Token,
 925                            ket: &token::Token,
 926                            sep: SeqSep,
 927                            f: F)
 928                            -> PResult<'a, Spanned<Vec<T>>> where
 929         F: FnMut(&mut Parser<'a>) -> PResult<'a,  T>,
 930     {
 931         let lo = self.span.lo;
 932         try!(self.expect(bra));
 933         let result = try!(self.parse_seq_to_before_end(ket, sep, f));
 934         let hi = self.span.hi;
 935         self.bump();
 936         Ok(spanned(lo, hi, result))
 937     }
 938
 939     /// Advance the parser by one token
 940     pub fn bump(&mut self) {
 941         self.last_span = self.span;
 942         // Stash token for error recovery (sometimes; clone is not necessarily cheap).
 943         self.last_token = if self.token.is_ident() ||
 944                           self.token.is_path() ||
 945                           self.token == token::Comma {
 946             Some(Box::new(self.token.clone()))
 947         } else {
 948             None
 949         };
 950         self.last_token_interpolated = self.token.is_interpolated();
 951         let next = if self.buffer_start == self.buffer_end {
 952             self.reader.real_token()
 953         } else {
 954             // Avoid token copies with `replace`.
 955             let buffer_start = self.buffer_start as usize;
 956             let next_index = (buffer_start + 1) & 3;
 957             self.buffer_start = next_index as isize;
 958
 959             let placeholder = TokenAndSpan {
 960                 tok: token::Underscore,
 961                 sp: self.span,
 962             };
 963             mem::replace(&mut self.buffer[buffer_start], placeholder)
 964         };
 965         self.span = next.sp;
 966         self.token = next.tok;
 967         self.tokens_consumed += 1;
 968         self.expected_tokens.clear();
 969         // check after each token
 970         self.check_unknown_macro_variable();
 971     }
 972
 973     /// Advance the parser by one token and return the bumped token.
 974     pub fn bump_and_get(&mut self) -> token::Token {
 975         let old_token = mem::replace(&mut self.token, token::Underscore);
 976         self.bump();
 977         old_token
 978     }
 979
 980     /// EFFECT: replace the current token and span with the given one
 981     pub fn replace_token(&mut self,
 982                          next: token::Token,
 983                          lo: BytePos,
 984                          hi: BytePos) {
 985         self.last_span = mk_sp(self.span.lo, lo);
 986         self.token = next;
 987         self.span = mk_sp(lo, hi);
 988     }
 989     pub fn buffer_length(&mut self) -> isize {
 990         if self.buffer_start <= self.buffer_end {
 991             return self.buffer_end - self.buffer_start;
 992         }
 993         return (4 - self.buffer_start) + self.buffer_end;
 994     }
 995     pub fn look_ahead<R, F>(&mut self, distance: usize, f: F) -> R where
 996         F: FnOnce(&token::Token) -> R,
 997     {
 998         let dist = distance as isize;
 999         while self.buffer_length() < dist {
1000             self.buffer[self.buffer_end as usize] = self.reader.real_token();
1001             self.buffer_end = (self.buffer_end + 1) & 3;
1002         }
1003         f(&self.buffer[((self.buffer_start + dist - 1) & 3) as usize].tok)
1004     }
1005     pub fn fatal(&self, m: &str) -> DiagnosticBuilder<'a> {
1006         self.sess.span_diagnostic.struct_span_fatal(self.span, m)
1007     }
1008     pub fn span_fatal(&self, sp: Span, m: &str) -> DiagnosticBuilder<'a> {
1009         self.sess.span_diagnostic.struct_span_fatal(sp, m)
1010     }
1011     pub fn span_fatal_help(&self, sp: Span, m: &str, help: &str) -> DiagnosticBuilder<'a> {
1012         let mut err = self.sess.span_diagnostic.struct_span_fatal(sp, m);
1013         err.fileline_help(sp, help);
1014         err
1015     }
1016     pub fn bug(&self, m: &str) -> ! {
1017         self.sess.span_diagnostic.span_bug(self.span, m)
1018     }
1019     pub fn warn(&self, m: &str) {
1020         self.sess.span_diagnostic.span_warn(self.span, m)
1021     }
1022     pub fn span_warn(&self, sp: Span, m: &str) {
1023         self.sess.span_diagnostic.span_warn(sp, m)
1024     }
1025     pub fn span_err(&self, sp: Span, m: &str) {
1026         self.sess.span_diagnostic.span_err(sp, m)
1027     }
1028     pub fn span_bug(&self, sp: Span, m: &str) -> ! {
1029         self.sess.span_diagnostic.span_bug(sp, m)
1030     }
1031     pub fn abort_if_errors(&self) {
1032         self.sess.span_diagnostic.abort_if_errors();
1033     }
1034
1035     pub fn diagnostic(&self) -> &'a errors::Handler {
1036         &self.sess.span_diagnostic
1037     }
1038
1039     pub fn id_to_interned_str(&mut self, id: Ident) -> InternedString {
1040         id.name.as_str()
1041     }
1042
1043     /// Is the current token one of the keywords that signals a bare function
1044     /// type?
1045     pub fn token_is_bare_fn_keyword(&mut self) -> bool {
1046         self.check_keyword(keywords::Fn) ||
1047             self.check_keyword(keywords::Unsafe) ||
1048             self.check_keyword(keywords::Extern)
1049     }
1050
1051     pub fn get_lifetime(&mut self) -> ast::Ident {
1052         match self.token {
1053             token::Lifetime(ref ident) => *ident,
1054             _ => self.bug("not a lifetime"),
1055         }
1056     }
1057
1058     pub fn parse_for_in_type(&mut self) -> PResult<'a, Ty_> {
1059         /*
1060         Parses whatever can come after a `for` keyword in a type.
1061         The `for` has already been consumed.
1062
1063         Deprecated:
1064
1065         - for <'lt> |S| -> T
1066
1067         Eventually:
1068
1069         - for <'lt> [unsafe] [extern "ABI"] fn (S) -> T
1070         - for <'lt> path::foo(a, b)
1071
1072         */
1073
1074         // parse <'lt>
1075         let lo = self.span.lo;
1076
1077         let lifetime_defs = try!(self.parse_late_bound_lifetime_defs());
1078
1079         // examine next token to decide to do
1080         if self.token_is_bare_fn_keyword() {
1081             self.parse_ty_bare_fn(lifetime_defs)
1082         } else {
1083             let hi = self.span.hi;
1084             let trait_ref = try!(self.parse_trait_ref());
1085             let poly_trait_ref = ast::PolyTraitRef { bound_lifetimes: lifetime_defs,
1086                                                      trait_ref: trait_ref,
1087                                                      span: mk_sp(lo, hi)};
1088             let other_bounds = if self.eat(&token::BinOp(token::Plus)) {
1089                 try!(self.parse_ty_param_bounds(BoundParsingMode::Bare))
1090             } else {
1091                 P::empty()
1092             };
1093             let all_bounds =
1094                 Some(TraitTyParamBound(poly_trait_ref, TraitBoundModifier::None)).into_iter()
1095                 .chain(other_bounds.into_vec())
1096                 .collect();
1097             Ok(ast::TyPolyTraitRef(all_bounds))
1098         }
1099     }
1100
1101     pub fn parse_ty_path(&mut self) -> PResult<'a, Ty_> {
1102         Ok(TyPath(None, try!(self.parse_path(LifetimeAndTypesWithoutColons))))
1103     }
1104
1105     /// parse a TyBareFn type:
1106     pub fn parse_ty_bare_fn(&mut self, lifetime_defs: Vec<ast::LifetimeDef>) -> PResult<'a, Ty_> {
1107         /*
1108
1109         [unsafe] [extern "ABI"] fn <'lt> (S) -> T
1110          ^~~~^           ^~~~^     ^~~~^ ^~^    ^
1111            |               |         |    |     |
1112            |               |         |    |   Return type
1113            |               |         |  Argument types
1114            |               |     Lifetimes
1115            |              ABI
1116         Function Style
1117         */
1118
1119         let unsafety = try!(self.parse_unsafety());
1120         let abi = if self.eat_keyword(keywords::Extern) {
1121             try!(self.parse_opt_abi()).unwrap_or(abi::C)
1122         } else {
1123             abi::Rust
1124         };
1125
1126         try!(self.expect_keyword(keywords::Fn));
1127         let (inputs, variadic) = try!(self.parse_fn_args(false, true));
1128         let ret_ty = try!(self.parse_ret_ty());
1129         let decl = P(FnDecl {
1130             inputs: inputs,
1131             output: ret_ty,
1132             variadic: variadic
1133         });
1134         Ok(TyBareFn(P(BareFnTy {
1135             abi: abi,
1136             unsafety: unsafety,
1137             lifetimes: lifetime_defs,
1138             decl: decl
1139         })))
1140     }
1141
1142     /// Parses an obsolete closure kind (`&:`, `&mut:`, or `:`).
1143     pub fn parse_obsolete_closure_kind(&mut self) -> PResult<'a, ()> {
1144          let lo = self.span.lo;
1145         if
1146             self.check(&token::BinOp(token::And)) &&
1147             self.look_ahead(1, |t| t.is_keyword(keywords::Mut)) &&
1148             self.look_ahead(2, |t| *t == token::Colon)
1149         {
1150             self.bump();
1151             self.bump();
1152             self.bump();
1153         } else if
1154             self.token == token::BinOp(token::And) &&
1155             self.look_ahead(1, |t| *t == token::Colon)
1156         {
1157             self.bump();
1158             self.bump();
1159         } else if
1160             self.eat(&token::Colon)
1161         {
1162             /* nothing */
1163         } else {
1164             return Ok(());
1165         }
1166
1167         let span = mk_sp(lo, self.span.hi);
1168         self.obsolete(span, ObsoleteSyntax::ClosureKind);
1169         Ok(())
1170     }
1171
1172     pub fn parse_unsafety(&mut self) -> PResult<'a, Unsafety> {
1173         if self.eat_keyword(keywords::Unsafe) {
1174             return Ok(Unsafety::Unsafe);
1175         } else {
1176             return Ok(Unsafety::Normal);
1177         }
1178     }
1179
1180     /// Parse the items in a trait declaration
1181     pub fn parse_trait_items(&mut self) -> PResult<'a,  Vec<P<TraitItem>>> {
1182         self.parse_unspanned_seq(
1183             &token::OpenDelim(token::Brace),
1184             &token::CloseDelim(token::Brace),
1185             seq_sep_none(),
1186             |p| -> PResult<'a, P<TraitItem>> {
1187             maybe_whole!(no_clone p, NtTraitItem);
1188             let mut attrs = try!(p.parse_outer_attributes());
1189             let lo = p.span.lo;
1190
1191             let (name, node) = if p.eat_keyword(keywords::Type) {
1192                 let TyParam {ident, bounds, default, ..} = try!(p.parse_ty_param());
1193                 try!(p.expect(&token::Semi));
1194                 (ident, TypeTraitItem(bounds, default))
1195             } else if p.is_const_item() {
1196                 try!(p.expect_keyword(keywords::Const));
1197                 let ident = try!(p.parse_ident());
1198                 try!(p.expect(&token::Colon));
1199                 let ty = try!(p.parse_ty_sum());
1200                 let default = if p.check(&token::Eq) {
1201                     p.bump();
1202                     let expr = try!(p.parse_expr());
1203                     try!(p.commit_expr_expecting(&expr, token::Semi));
1204                     Some(expr)
1205                 } else {
1206                     try!(p.expect(&token::Semi));
1207                     None
1208                 };
1209                 (ident, ConstTraitItem(ty, default))
1210             } else {
1211                 let (constness, unsafety, abi) = try!(p.parse_fn_front_matter());
1212
1213                 let ident = try!(p.parse_ident());
1214                 let mut generics = try!(p.parse_generics());
1215
1216                 let (explicit_self, d) = try!(p.parse_fn_decl_with_self(|p: &mut Parser<'a>|{
1217                     // This is somewhat dubious; We don't want to allow
1218                     // argument names to be left off if there is a
1219                     // definition...
1220                     p.parse_arg_general(false)
1221                 }));
1222
1223                 generics.where_clause = try!(p.parse_where_clause());
1224                 let sig = ast::MethodSig {
1225                     unsafety: unsafety,
1226                     constness: constness,
1227                     decl: d,
1228                     generics: generics,
1229                     abi: abi,
1230                     explicit_self: explicit_self,
1231                 };
1232
1233                 let body = match p.token {
1234                   token::Semi => {
1235                     p.bump();
1236                     debug!("parse_trait_methods(): parsing required method");
1237                     None
1238                   }
1239                   token::OpenDelim(token::Brace) => {
1240                     debug!("parse_trait_methods(): parsing provided method");
1241                     let (inner_attrs, body) =
1242                         try!(p.parse_inner_attrs_and_block());
1243                     attrs.extend(inner_attrs.iter().cloned());
1244                     Some(body)
1245                   }
1246
1247                   _ => {
1248                       let token_str = p.this_token_to_string();
1249                       return Err(p.fatal(&format!("expected `;` or `{{`, found `{}`",
1250                                        token_str)[..]))
1251                   }
1252                 };
1253                 (ident, ast::MethodTraitItem(sig, body))
1254             };
1255
1256             Ok(P(TraitItem {
1257                 id: ast::DUMMY_NODE_ID,
1258                 ident: name,
1259                 attrs: attrs,
1260                 node: node,
1261                 span: mk_sp(lo, p.last_span.hi),
1262             }))
1263         })
1264     }
1265
1266     /// Parse a possibly mutable type
1267     pub fn parse_mt(&mut self) -> PResult<'a, MutTy> {
1268         let mutbl = try!(self.parse_mutability());
1269         let t = try!(self.parse_ty());
1270         Ok(MutTy { ty: t, mutbl: mutbl })
1271     }
1272
1273     /// Parse optional return type [ -> TY ] in function decl
1274     pub fn parse_ret_ty(&mut self) -> PResult<'a, FunctionRetTy> {
1275         if self.eat(&token::RArrow) {
1276             if self.eat(&token::Not) {
1277                 Ok(NoReturn(self.last_span))
1278             } else {
1279                 Ok(Return(try!(self.parse_ty())))
1280             }
1281         } else {
1282             let pos = self.span.lo;
1283             Ok(DefaultReturn(mk_sp(pos, pos)))
1284         }
1285     }
1286
1287     /// Parse a type in a context where `T1+T2` is allowed.
1288     pub fn parse_ty_sum(&mut self) -> PResult<'a, P<Ty>> {
1289         let lo = self.span.lo;
1290         let lhs = try!(self.parse_ty());
1291
1292         if !self.eat(&token::BinOp(token::Plus)) {
1293             return Ok(lhs);
1294         }
1295
1296         let bounds = try!(self.parse_ty_param_bounds(BoundParsingMode::Bare));
1297
1298         // In type grammar, `+` is treated like a binary operator,
1299         // and hence both L and R side are required.
1300         if bounds.is_empty() {
1301             let last_span = self.last_span;
1302             self.span_err(last_span,
1303                           "at least one type parameter bound \
1304                           must be specified");
1305         }
1306
1307         let sp = mk_sp(lo, self.last_span.hi);
1308         let sum = ast::TyObjectSum(lhs, bounds);
1309         Ok(P(Ty {id: ast::DUMMY_NODE_ID, node: sum, span: sp}))
1310     }
1311
1312     /// Parse a type.
1313     pub fn parse_ty(&mut self) -> PResult<'a, P<Ty>> {
1314         maybe_whole!(no_clone self, NtTy);
1315
1316         let lo = self.span.lo;
1317
1318         let t = if self.check(&token::OpenDelim(token::Paren)) {
1319             self.bump();
1320
1321             // (t) is a parenthesized ty
1322             // (t,) is the type of a tuple with only one field,
1323             // of type t
1324             let mut ts = vec![];
1325             let mut last_comma = false;
1326             while self.token != token::CloseDelim(token::Paren) {
1327                 ts.push(try!(self.parse_ty_sum()));
1328                 if self.check(&token::Comma) {
1329                     last_comma = true;
1330                     self.bump();
1331                 } else {
1332                     last_comma = false;
1333                     break;
1334                 }
1335             }
1336
1337             try!(self.expect(&token::CloseDelim(token::Paren)));
1338             if ts.len() == 1 && !last_comma {
1339                 TyParen(ts.into_iter().nth(0).unwrap())
1340             } else {
1341                 TyTup(ts)
1342             }
1343         } else if self.check(&token::BinOp(token::Star)) {
1344             // STAR POINTER (bare pointer?)
1345             self.bump();
1346             TyPtr(try!(self.parse_ptr()))
1347         } else if self.check(&token::OpenDelim(token::Bracket)) {
1348             // VECTOR
1349             try!(self.expect(&token::OpenDelim(token::Bracket)));
1350             let t = try!(self.parse_ty_sum());
1351
1352             // Parse the `; e` in `[ i32; e ]`
1353             // where `e` is a const expression
1354             let t = match try!(self.maybe_parse_fixed_length_of_vec()) {
1355                 None => TyVec(t),
1356                 Some(suffix) => TyFixedLengthVec(t, suffix)
1357             };
1358             try!(self.expect(&token::CloseDelim(token::Bracket)));
1359             t
1360         } else if self.check(&token::BinOp(token::And)) ||
1361                   self.token == token::AndAnd {
1362             // BORROWED POINTER
1363             try!(self.expect_and());
1364             try!(self.parse_borrowed_pointee())
1365         } else if self.check_keyword(keywords::For) {
1366             try!(self.parse_for_in_type())
1367         } else if self.token_is_bare_fn_keyword() {
1368             // BARE FUNCTION
1369             try!(self.parse_ty_bare_fn(Vec::new()))
1370         } else if self.eat_keyword_noexpect(keywords::Typeof) {
1371             // TYPEOF
1372             // In order to not be ambiguous, the type must be surrounded by parens.
1373             try!(self.expect(&token::OpenDelim(token::Paren)));
1374             let e = try!(self.parse_expr());
1375             try!(self.expect(&token::CloseDelim(token::Paren)));
1376             TyTypeof(e)
1377         } else if self.eat_lt() {
1378
1379             let (qself, path) =
1380                  try!(self.parse_qualified_path(NoTypesAllowed));
1381
1382             TyPath(Some(qself), path)
1383         } else if self.check(&token::ModSep) ||
1384                   self.token.is_ident() ||
1385                   self.token.is_path() {
1386             let path = try!(self.parse_path(LifetimeAndTypesWithoutColons));
1387             if self.check(&token::Not) {
1388                 // MACRO INVOCATION
1389                 self.bump();
1390                 let delim = try!(self.expect_open_delim());
1391                 let tts = try!(self.parse_seq_to_end(&token::CloseDelim(delim),
1392                                                      seq_sep_none(),
1393                                                      |p| p.parse_token_tree()));
1394                 let hi = self.span.hi;
1395                 TyMac(spanned(lo, hi, Mac_ { path: path, tts: tts, ctxt: EMPTY_CTXT }))
1396             } else {
1397                 // NAMED TYPE
1398                 TyPath(None, path)
1399             }
1400         } else if self.eat(&token::Underscore) {
1401             // TYPE TO BE INFERRED
1402             TyInfer
1403         } else {
1404             let this_token_str = self.this_token_to_string();
1405             let msg = format!("expected type, found `{}`", this_token_str);
1406             return Err(self.fatal(&msg[..]));
1407         };
1408
1409         let sp = mk_sp(lo, self.last_span.hi);
1410         Ok(P(Ty {id: ast::DUMMY_NODE_ID, node: t, span: sp}))
1411     }
1412
1413     pub fn parse_borrowed_pointee(&mut self) -> PResult<'a, Ty_> {
1414         // look for `&'lt` or `&'foo ` and interpret `foo` as the region name:
1415         let opt_lifetime = try!(self.parse_opt_lifetime());
1416
1417         let mt = try!(self.parse_mt());
1418         return Ok(TyRptr(opt_lifetime, mt));
1419     }
1420
1421     pub fn parse_ptr(&mut self) -> PResult<'a, MutTy> {
1422         let mutbl = if self.eat_keyword(keywords::Mut) {
1423             MutMutable
1424         } else if self.eat_keyword(keywords::Const) {
1425             MutImmutable
1426         } else {
1427             let span = self.last_span;
1428             self.span_err(span,
1429                           "bare raw pointers are no longer allowed, you should \
1430                            likely use `*mut T`, but otherwise `*T` is now \
1431                            known as `*const T`");
1432             MutImmutable
1433         };
1434         let t = try!(self.parse_ty());
1435         Ok(MutTy { ty: t, mutbl: mutbl })
1436     }
1437
1438     pub fn is_named_argument(&mut self) -> bool {
1439         let offset = match self.token {
1440             token::BinOp(token::And) => 1,
1441             token::AndAnd => 1,
1442             _ if self.token.is_keyword(keywords::Mut) => 1,
1443             _ => 0
1444         };
1445
1446         debug!("parser is_named_argument offset:{}", offset);
1447
1448         if offset == 0 {
1449             is_plain_ident_or_underscore(&self.token)
1450                 && self.look_ahead(1, |t| *t == token::Colon)
1451         } else {
1452             self.look_ahead(offset, |t| is_plain_ident_or_underscore(t))
1453                 && self.look_ahead(offset + 1, |t| *t == token::Colon)
1454         }
1455     }
1456
1457     /// This version of parse arg doesn't necessarily require
1458     /// identifier names.
1459     pub fn parse_arg_general(&mut self, require_name: bool) -> PResult<'a, Arg> {
1460         maybe_whole!(no_clone self, NtArg);
1461
1462         let pat = if require_name || self.is_named_argument() {
1463             debug!("parse_arg_general parse_pat (require_name:{})",
1464                    require_name);
1465             let pat = try!(self.parse_pat());
1466
1467             try!(self.expect(&token::Colon));
1468             pat
1469         } else {
1470             debug!("parse_arg_general ident_to_pat");
1471             ast_util::ident_to_pat(ast::DUMMY_NODE_ID,
1472                                    self.last_span,
1473                                    special_idents::invalid)
1474         };
1475
1476         let t = try!(self.parse_ty_sum());
1477
1478         Ok(Arg {
1479             ty: t,
1480             pat: pat,
1481             id: ast::DUMMY_NODE_ID,
1482         })
1483     }
1484
1485     /// Parse a single function argument
1486     pub fn parse_arg(&mut self) -> PResult<'a, Arg> {
1487         self.parse_arg_general(true)
1488     }
1489
1490     /// Parse an argument in a lambda header e.g. |arg, arg|
1491     pub fn parse_fn_block_arg(&mut self) -> PResult<'a, Arg> {
1492         let pat = try!(self.parse_pat());
1493         let t = if self.eat(&token::Colon) {
1494             try!(self.parse_ty_sum())
1495         } else {
1496             P(Ty {
1497                 id: ast::DUMMY_NODE_ID,
1498                 node: TyInfer,
1499                 span: mk_sp(self.span.lo, self.span.hi),
1500             })
1501         };
1502         Ok(Arg {
1503             ty: t,
1504             pat: pat,
1505             id: ast::DUMMY_NODE_ID
1506         })
1507     }
1508
1509     pub fn maybe_parse_fixed_length_of_vec(&mut self) -> PResult<'a, Option<P<ast::Expr>>> {
1510         if self.check(&token::Semi) {
1511             self.bump();
1512             Ok(Some(try!(self.parse_expr())))
1513         } else {
1514             Ok(None)
1515         }
1516     }
1517
1518     /// Matches token_lit = LIT_INTEGER | ...
1519     pub fn lit_from_token(&self, tok: &token::Token) -> PResult<'a, Lit_> {
1520         match *tok {
1521             token::Interpolated(token::NtExpr(ref v)) => {
1522                 match v.node {
1523                     ExprLit(ref lit) => { Ok(lit.node.clone()) }
1524                     _ => { return self.unexpected_last(tok); }
1525                 }
1526             }
1527             token::Literal(lit, suf) => {
1528                 let (suffix_illegal, out) = match lit {
1529                     token::Byte(i) => (true, LitByte(parse::byte_lit(&i.as_str()).0)),
1530                     token::Char(i) => (true, LitChar(parse::char_lit(&i.as_str()).0)),
1531
1532                     // there are some valid suffixes for integer and
1533                     // float literals, so all the handling is done
1534                     // internally.
1535                     token::Integer(s) => {
1536                         (false, parse::integer_lit(&s.as_str(),
1537                                                    suf.as_ref().map(|s| s.as_str()),
1538                                                    &self.sess.span_diagnostic,
1539                                                    self.last_span))
1540                     }
1541                     token::Float(s) => {
1542                         (false, parse::float_lit(&s.as_str(),
1543                                                  suf.as_ref().map(|s| s.as_str()),
1544                                                   &self.sess.span_diagnostic,
1545                                                  self.last_span))
1546                     }
1547
1548                     token::Str_(s) => {
1549                         (true,
1550                          LitStr(token::intern_and_get_ident(&parse::str_lit(&s.as_str())),
1551                                 ast::CookedStr))
1552                     }
1553                     token::StrRaw(s, n) => {
1554                         (true,
1555                          LitStr(
1556                             token::intern_and_get_ident(&parse::raw_str_lit(&s.as_str())),
1557                             ast::RawStr(n)))
1558                     }
1559                     token::ByteStr(i) =>
1560                         (true, LitByteStr(parse::byte_str_lit(&i.as_str()))),
1561                     token::ByteStrRaw(i, _) =>
1562                         (true,
1563                          LitByteStr(Rc::new(i.to_string().into_bytes()))),
1564                 };
1565
1566                 if suffix_illegal {
1567                     let sp = self.last_span;
1568                     self.expect_no_suffix(sp, &*format!("{} literal", lit.short_name()), suf)
1569                 }
1570
1571                 Ok(out)
1572             }
1573             _ => { return self.unexpected_last(tok); }
1574         }
1575     }
1576
1577     /// Matches lit = true | false | token_lit
1578     pub fn parse_lit(&mut self) -> PResult<'a, Lit> {
1579         let lo = self.span.lo;
1580         let lit = if self.eat_keyword(keywords::True) {
1581             LitBool(true)
1582         } else if self.eat_keyword(keywords::False) {
1583             LitBool(false)
1584         } else {
1585             let token = self.bump_and_get();
1586             let lit = try!(self.lit_from_token(&token));
1587             lit
1588         };
1589         Ok(codemap::Spanned { node: lit, span: mk_sp(lo, self.last_span.hi) })
1590     }
1591
1592     /// matches '-' lit | lit
1593     pub fn parse_pat_literal_maybe_minus(&mut self) -> PResult<'a, P<Expr>> {
1594         let minus_lo = self.span.lo;
1595         let minus_present = self.eat(&token::BinOp(token::Minus));
1596         let lo = self.span.lo;
1597         let literal = P(try!(self.parse_lit()));
1598         let hi = self.last_span.hi;
1599         let expr = self.mk_expr(lo, hi, ExprLit(literal), None);
1600
1601         if minus_present {
1602             let minus_hi = self.last_span.hi;
1603             let unary = self.mk_unary(UnNeg, expr);
1604             Ok(self.mk_expr(minus_lo, minus_hi, unary, None))
1605         } else {
1606             Ok(expr)
1607         }
1608     }
1609
1610     /// Parses qualified path.
1611     ///
1612     /// Assumes that the leading `<` has been parsed already.
1613     ///
1614     /// Qualifed paths are a part of the universal function call
1615     /// syntax (UFCS).
1616     ///
1617     /// `qualified_path = <type [as trait_ref]>::path`
1618     ///
1619     /// See `parse_path` for `mode` meaning.
1620     ///
1621     /// # Examples:
1622     ///
1623     /// `<T as U>::a`
1624     /// `<T as U>::F::a::<S>`
1625     pub fn parse_qualified_path(&mut self, mode: PathParsingMode)
1626                                 -> PResult<'a, (QSelf, ast::Path)> {
1627         let span = self.last_span;
1628         let self_type = try!(self.parse_ty_sum());
1629         let mut path = if self.eat_keyword(keywords::As) {
1630             try!(self.parse_path(LifetimeAndTypesWithoutColons))
1631         } else {
1632             ast::Path {
1633                 span: span,
1634                 global: false,
1635                 segments: vec![]
1636             }
1637         };
1638
1639         let qself = QSelf {
1640             ty: self_type,
1641             position: path.segments.len()
1642         };
1643
1644         try!(self.expect(&token::Gt));
1645         try!(self.expect(&token::ModSep));
1646
1647         let segments = match mode {
1648             LifetimeAndTypesWithoutColons => {
1649                 try!(self.parse_path_segments_without_colons())
1650             }
1651             LifetimeAndTypesWithColons => {
1652                 try!(self.parse_path_segments_with_colons())
1653             }
1654             NoTypesAllowed => {
1655                 try!(self.parse_path_segments_without_types())
1656             }
1657         };
1658         path.segments.extend(segments);
1659
1660         path.span.hi = self.last_span.hi;
1661
1662         Ok((qself, path))
1663     }
1664
1665     /// Parses a path and optional type parameter bounds, depending on the
1666     /// mode. The `mode` parameter determines whether lifetimes, types, and/or
1667     /// bounds are permitted and whether `::` must precede type parameter
1668     /// groups.
1669     pub fn parse_path(&mut self, mode: PathParsingMode) -> PResult<'a, ast::Path> {
1670         // Check for a whole path...
1671         let found = match self.token {
1672             token::Interpolated(token::NtPath(_)) => Some(self.bump_and_get()),
1673             _ => None,
1674         };
1675         if let Some(token::Interpolated(token::NtPath(path))) = found {
1676             return Ok(*path);
1677         }
1678
1679         let lo = self.span.lo;
1680         let is_global = self.eat(&token::ModSep);
1681
1682         // Parse any number of segments and bound sets. A segment is an
1683         // identifier followed by an optional lifetime and a set of types.
1684         // A bound set is a set of type parameter bounds.
1685         let segments = match mode {
1686             LifetimeAndTypesWithoutColons => {
1687                 try!(self.parse_path_segments_without_colons())
1688             }
1689             LifetimeAndTypesWithColons => {
1690                 try!(self.parse_path_segments_with_colons())
1691             }
1692             NoTypesAllowed => {
1693                 try!(self.parse_path_segments_without_types())
1694             }
1695         };
1696
1697         // Assemble the span.
1698         let span = mk_sp(lo, self.last_span.hi);
1699
1700         // Assemble the result.
1701         Ok(ast::Path {
1702             span: span,
1703             global: is_global,
1704             segments: segments,
1705         })
1706     }
1707
1708     /// Examples:
1709     /// - `a::b<T,U>::c<V,W>`
1710     /// - `a::b<T,U>::c(V) -> W`
1711     /// - `a::b<T,U>::c(V)`
1712     pub fn parse_path_segments_without_colons(&mut self) -> PResult<'a, Vec<ast::PathSegment>> {
1713         let mut segments = Vec::new();
1714         loop {
1715             // First, parse an identifier.
1716             let identifier = try!(self.parse_ident_or_self_type());
1717
1718             // Parse types, optionally.
1719             let parameters = if self.eat_lt() {
1720                 let (lifetimes, types, bindings) = try!(self.parse_generic_values_after_lt());
1721
1722                 ast::PathParameters::AngleBracketed(ast::AngleBracketedParameterData {
1723                     lifetimes: lifetimes,
1724                     types: P::from_vec(types),
1725                     bindings: P::from_vec(bindings),
1726                 })
1727             } else if self.eat(&token::OpenDelim(token::Paren)) {
1728                 let lo = self.last_span.lo;
1729
1730                 let inputs = try!(self.parse_seq_to_end(
1731                     &token::CloseDelim(token::Paren),
1732                     seq_sep_trailing_allowed(token::Comma),
1733                     |p| p.parse_ty_sum()));
1734
1735                 let output_ty = if self.eat(&token::RArrow) {
1736                     Some(try!(self.parse_ty()))
1737                 } else {
1738                     None
1739                 };
1740
1741                 let hi = self.last_span.hi;
1742
1743                 ast::PathParameters::Parenthesized(ast::ParenthesizedParameterData {
1744                     span: mk_sp(lo, hi),
1745                     inputs: inputs,
1746                     output: output_ty,
1747                 })
1748             } else {
1749                 ast::PathParameters::none()
1750             };
1751
1752             // Assemble and push the result.
1753             segments.push(ast::PathSegment { identifier: identifier,
1754                                              parameters: parameters });
1755
1756             // Continue only if we see a `::`
1757             if !self.eat(&token::ModSep) {
1758                 return Ok(segments);
1759             }
1760         }
1761     }
1762
1763     /// Examples:
1764     /// - `a::b::<T,U>::c`
1765     pub fn parse_path_segments_with_colons(&mut self) -> PResult<'a, Vec<ast::PathSegment>> {
1766         let mut segments = Vec::new();
1767         loop {
1768             // First, parse an identifier.
1769             let identifier = try!(self.parse_ident_or_self_type());
1770
1771             // If we do not see a `::`, stop.
1772             if !self.eat(&token::ModSep) {
1773                 segments.push(ast::PathSegment {
1774                     identifier: identifier,
1775                     parameters: ast::PathParameters::none()
1776                 });
1777                 return Ok(segments);
1778             }
1779
1780             // Check for a type segment.
1781             if self.eat_lt() {
1782                 // Consumed `a::b::<`, go look for types
1783                 let (lifetimes, types, bindings) = try!(self.parse_generic_values_after_lt());
1784                 let parameters = ast::AngleBracketedParameterData {
1785                     lifetimes: lifetimes,
1786                     types: P::from_vec(types),
1787                     bindings: P::from_vec(bindings),
1788                 };
1789                 segments.push(ast::PathSegment {
1790                     identifier: identifier,
1791                     parameters: ast::PathParameters::AngleBracketed(parameters),
1792                 });
1793
1794                 // Consumed `a::b::<T,U>`, check for `::` before proceeding
1795                 if !self.eat(&token::ModSep) {
1796                     return Ok(segments);
1797                 }
1798             } else {
1799                 // Consumed `a::`, go look for `b`
1800                 segments.push(ast::PathSegment {
1801                     identifier: identifier,
1802                     parameters: ast::PathParameters::none(),
1803                 });
1804             }
1805         }
1806     }
1807
1808
1809     /// Examples:
1810     /// - `a::b::c`
1811     pub fn parse_path_segments_without_types(&mut self) -> PResult<'a, Vec<ast::PathSegment>> {
1812         let mut segments = Vec::new();
1813         loop {
1814             // First, parse an identifier.
1815             let identifier = try!(self.parse_ident_or_self_type());
1816
1817             // Assemble and push the result.
1818             segments.push(ast::PathSegment {
1819                 identifier: identifier,
1820                 parameters: ast::PathParameters::none()
1821             });
1822
1823             // If we do not see a `::`, stop.
1824             if !self.eat(&token::ModSep) {
1825                 return Ok(segments);
1826             }
1827         }
1828     }
1829
1830     /// parses 0 or 1 lifetime
1831     pub fn parse_opt_lifetime(&mut self) -> PResult<'a, Option<ast::Lifetime>> {
1832         match self.token {
1833             token::Lifetime(..) => {
1834                 Ok(Some(try!(self.parse_lifetime())))
1835             }
1836             _ => {
1837                 Ok(None)
1838             }
1839         }
1840     }
1841
1842     /// Parses a single lifetime
1843     /// Matches lifetime = LIFETIME
1844     pub fn parse_lifetime(&mut self) -> PResult<'a, ast::Lifetime> {
1845         match self.token {
1846             token::Lifetime(i) => {
1847                 let span = self.span;
1848                 self.bump();
1849                 return Ok(ast::Lifetime {
1850                     id: ast::DUMMY_NODE_ID,
1851                     span: span,
1852                     name: i.name
1853                 });
1854             }
1855             _ => {
1856                 return Err(self.fatal("expected a lifetime name"));
1857             }
1858         }
1859     }
1860
1861     /// Parses `lifetime_defs = [ lifetime_defs { ',' lifetime_defs } ]` where `lifetime_def  =
1862     /// lifetime [':' lifetimes]`
1863     pub fn parse_lifetime_defs(&mut self) -> PResult<'a, Vec<ast::LifetimeDef>> {
1864
1865         let mut res = Vec::new();
1866         loop {
1867             match self.token {
1868                 token::Lifetime(_) => {
1869                     let lifetime = try!(self.parse_lifetime());
1870                     let bounds =
1871                         if self.eat(&token::Colon) {
1872                             try!(self.parse_lifetimes(token::BinOp(token::Plus)))
1873                         } else {
1874                             Vec::new()
1875                         };
1876                     res.push(ast::LifetimeDef { lifetime: lifetime,
1877                                                 bounds: bounds });
1878                 }
1879
1880                 _ => {
1881                     return Ok(res);
1882                 }
1883             }
1884
1885             match self.token {
1886                 token::Comma => { self.bump();}
1887                 token::Gt => { return Ok(res); }
1888                 token::BinOp(token::Shr) => { return Ok(res); }
1889                 _ => {
1890                     let this_token_str = self.this_token_to_string();
1891                     let msg = format!("expected `,` or `>` after lifetime \
1892                                       name, found `{}`",
1893                                       this_token_str);
1894                     return Err(self.fatal(&msg[..]));
1895                 }
1896             }
1897         }
1898     }
1899
1900     /// matches lifetimes = ( lifetime ) | ( lifetime , lifetimes ) actually, it matches the empty
1901     /// one too, but putting that in there messes up the grammar....
1902     ///
1903     /// Parses zero or more comma separated lifetimes. Expects each lifetime to be followed by
1904     /// either a comma or `>`.  Used when parsing type parameter lists, where we expect something
1905     /// like `<'a, 'b, T>`.
1906     pub fn parse_lifetimes(&mut self, sep: token::Token) -> PResult<'a, Vec<ast::Lifetime>> {
1907
1908         let mut res = Vec::new();
1909         loop {
1910             match self.token {
1911                 token::Lifetime(_) => {
1912                     res.push(try!(self.parse_lifetime()));
1913                 }
1914                 _ => {
1915                     return Ok(res);
1916                 }
1917             }
1918
1919             if self.token != sep {
1920                 return Ok(res);
1921             }
1922
1923             self.bump();
1924         }
1925     }
1926
1927     /// Parse mutability declaration (mut/const/imm)
1928     pub fn parse_mutability(&mut self) -> PResult<'a, Mutability> {
1929         if self.eat_keyword(keywords::Mut) {
1930             Ok(MutMutable)
1931         } else {
1932             Ok(MutImmutable)
1933         }
1934     }
1935
1936     /// Parse ident COLON expr
1937     pub fn parse_field(&mut self) -> PResult<'a, Field> {
1938         let lo = self.span.lo;
1939         let i = try!(self.parse_ident());
1940         let hi = self.last_span.hi;
1941         try!(self.expect(&token::Colon));
1942         let e = try!(self.parse_expr());
1943         Ok(ast::Field {
1944             ident: spanned(lo, hi, i),
1945             span: mk_sp(lo, e.span.hi),
1946             expr: e,
1947         })
1948     }
1949
1950     pub fn mk_expr(&mut self, lo: BytePos, hi: BytePos,
1951                    node: Expr_, attrs: ThinAttributes) -> P<Expr> {
1952         P(Expr {
1953             id: ast::DUMMY_NODE_ID,
1954             node: node,
1955             span: mk_sp(lo, hi),
1956             attrs: attrs,
1957         })
1958     }
1959
1960     pub fn mk_unary(&mut self, unop: ast::UnOp, expr: P<Expr>) -> ast::Expr_ {
1961         ExprUnary(unop, expr)
1962     }
1963
1964     pub fn mk_binary(&mut self, binop: ast::BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ast::Expr_ {
1965         ExprBinary(binop, lhs, rhs)
1966     }
1967
1968     pub fn mk_call(&mut self, f: P<Expr>, args: Vec<P<Expr>>) -> ast::Expr_ {
1969         ExprCall(f, args)
1970     }
1971
1972     fn mk_method_call(&mut self,
1973                       ident: ast::SpannedIdent,
1974                       tps: Vec<P<Ty>>,
1975                       args: Vec<P<Expr>>)
1976                       -> ast::Expr_ {
1977         ExprMethodCall(ident, tps, args)
1978     }
1979
1980     pub fn mk_index(&mut self, expr: P<Expr>, idx: P<Expr>) -> ast::Expr_ {
1981         ExprIndex(expr, idx)
1982     }
1983
1984     pub fn mk_range(&mut self,
1985                     start: Option<P<Expr>>,
1986                     end: Option<P<Expr>>)
1987                     -> ast::Expr_ {
1988         ExprRange(start, end)
1989     }
1990
1991     pub fn mk_field(&mut self, expr: P<Expr>, ident: ast::SpannedIdent) -> ast::Expr_ {
1992         ExprField(expr, ident)
1993     }
1994
1995     pub fn mk_tup_field(&mut self, expr: P<Expr>, idx: codemap::Spanned<usize>) -> ast::Expr_ {
1996         ExprTupField(expr, idx)
1997     }
1998
1999     pub fn mk_assign_op(&mut self, binop: ast::BinOp,
2000                         lhs: P<Expr>, rhs: P<Expr>) -> ast::Expr_ {
2001         ExprAssignOp(binop, lhs, rhs)
2002     }
2003
2004     pub fn mk_mac_expr(&mut self, lo: BytePos, hi: BytePos,
2005                        m: Mac_, attrs: ThinAttributes) -> P<Expr> {
2006         P(Expr {
2007             id: ast::DUMMY_NODE_ID,
2008             node: ExprMac(codemap::Spanned {node: m, span: mk_sp(lo, hi)}),
2009             span: mk_sp(lo, hi),
2010             attrs: attrs,
2011         })
2012     }
2013
2014     pub fn mk_lit_u32(&mut self, i: u32, attrs: ThinAttributes) -> P<Expr> {
2015         let span = &self.span;
2016         let lv_lit = P(codemap::Spanned {
2017             node: LitInt(i as u64, ast::UnsignedIntLit(TyU32)),
2018             span: *span
2019         });
2020
2021         P(Expr {
2022             id: ast::DUMMY_NODE_ID,
2023             node: ExprLit(lv_lit),
2024             span: *span,
2025             attrs: attrs,
2026         })
2027     }
2028
2029     fn expect_open_delim(&mut self) -> PResult<'a, token::DelimToken> {
2030         self.expected_tokens.push(TokenType::Token(token::Gt));
2031         match self.token {
2032             token::OpenDelim(delim) => {
2033                 self.bump();
2034                 Ok(delim)
2035             },
2036             _ => Err(self.fatal("expected open delimiter")),
2037         }
2038     }
2039
2040     /// At the bottom (top?) of the precedence hierarchy,
2041     /// parse things like parenthesized exprs,
2042     /// macros, return, etc.
2043     ///
2044     /// NB: This does not parse outer attributes,
2045     ///     and is private because it only works
2046     ///     correctly if called from parse_dot_or_call_expr().
2047     fn parse_bottom_expr(&mut self) -> PResult<'a, P<Expr>> {
2048         maybe_whole_expr!(self);
2049
2050         // Outer attributes are already parsed and will be
2051         // added to the return value after the fact.
2052         //
2053         // Therefore, prevent sub-parser from parsing
2054         // attributes by giving them a empty "already parsed" list.
2055         let mut attrs = None;
2056
2057         let lo = self.span.lo;
2058         let mut hi = self.span.hi;
2059
2060         let ex: Expr_;
2061
2062         // Note: when adding new syntax here, don't forget to adjust Token::can_begin_expr().
2063         match self.token {
2064             token::OpenDelim(token::Paren) => {
2065                 self.bump();
2066
2067                 let attrs = try!(self.parse_inner_attributes())
2068                     .into_thin_attrs()
2069                     .prepend(attrs);
2070
2071                 // (e) is parenthesized e
2072                 // (e,) is a tuple with only one field, e
2073                 let mut es = vec![];
2074                 let mut trailing_comma = false;
2075                 while self.token != token::CloseDelim(token::Paren) {
2076                     es.push(try!(self.parse_expr()));
2077                     try!(self.commit_expr(&**es.last().unwrap(), &[],
2078                                      &[token::Comma, token::CloseDelim(token::Paren)]));
2079                     if self.check(&token::Comma) {
2080                         trailing_comma = true;
2081
2082                         self.bump();
2083                     } else {
2084                         trailing_comma = false;
2085                         break;
2086                     }
2087                 }
2088                 self.bump();
2089
2090                 hi = self.last_span.hi;
2091                 return if es.len() == 1 && !trailing_comma {
2092                     Ok(self.mk_expr(lo, hi, ExprParen(es.into_iter().nth(0).unwrap()), attrs))
2093                 } else {
2094                     Ok(self.mk_expr(lo, hi, ExprTup(es), attrs))
2095                 }
2096             },
2097             token::OpenDelim(token::Brace) => {
2098                 return self.parse_block_expr(lo, DefaultBlock, attrs);
2099             },
2100             token::BinOp(token::Or) |  token::OrOr => {
2101                 let lo = self.span.lo;
2102                 return self.parse_lambda_expr(lo, CaptureByRef, attrs);
2103             },
2104             token::Ident(id @ ast::Ident {
2105                             name: token::SELF_KEYWORD_NAME,
2106                             ctxt: _
2107                          }, token::Plain) => {
2108                 self.bump();
2109                 let path = ast_util::ident_to_path(mk_sp(lo, hi), id);
2110                 ex = ExprPath(None, path);
2111                 hi = self.last_span.hi;
2112             }
2113             token::OpenDelim(token::Bracket) => {
2114                 self.bump();
2115
2116                 let inner_attrs = try!(self.parse_inner_attributes())
2117                     .into_thin_attrs();
2118                 attrs.update(|attrs| attrs.append(inner_attrs));
2119
2120                 if self.check(&token::CloseDelim(token::Bracket)) {
2121                     // Empty vector.
2122                     self.bump();
2123                     ex = ExprVec(Vec::new());
2124                 } else {
2125                     // Nonempty vector.
2126                     let first_expr = try!(self.parse_expr());
2127                     if self.check(&token::Semi) {
2128                         // Repeating array syntax: [ 0; 512 ]
2129                         self.bump();
2130                         let count = try!(self.parse_expr());
2131                         try!(self.expect(&token::CloseDelim(token::Bracket)));
2132                         ex = ExprRepeat(first_expr, count);
2133                     } else if self.check(&token::Comma) {
2134                         // Vector with two or more elements.
2135                         self.bump();
2136                         let remaining_exprs = try!(self.parse_seq_to_end(
2137                             &token::CloseDelim(token::Bracket),
2138                             seq_sep_trailing_allowed(token::Comma),
2139                             |p| Ok(try!(p.parse_expr()))
2140                                 ));
2141                         let mut exprs = vec!(first_expr);
2142                         exprs.extend(remaining_exprs);
2143                         ex = ExprVec(exprs);
2144                     } else {
2145                         // Vector with one element.
2146                         try!(self.expect(&token::CloseDelim(token::Bracket)));
2147                         ex = ExprVec(vec!(first_expr));
2148                     }
2149                 }
2150                 hi = self.last_span.hi;
2151             }
2152             _ => {
2153                 if self.eat_lt() {
2154                     let (qself, path) =
2155                         try!(self.parse_qualified_path(LifetimeAndTypesWithColons));
2156                     hi = path.span.hi;
2157                     return Ok(self.mk_expr(lo, hi, ExprPath(Some(qself), path), attrs));
2158                 }
2159                 if self.eat_keyword(keywords::Move) {
2160                     let lo = self.last_span.lo;
2161                     return self.parse_lambda_expr(lo, CaptureByValue, attrs);
2162                 }
2163                 if self.eat_keyword(keywords::If) {
2164                     return self.parse_if_expr(attrs);
2165                 }
2166                 if self.eat_keyword(keywords::For) {
2167                     let lo = self.last_span.lo;
2168                     return self.parse_for_expr(None, lo, attrs);
2169                 }
2170                 if self.eat_keyword(keywords::While) {
2171                     let lo = self.last_span.lo;
2172                     return self.parse_while_expr(None, lo, attrs);
2173                 }
2174                 if self.token.is_lifetime() {
2175                     let lifetime = self.get_lifetime();
2176                     let lo = self.span.lo;
2177                     self.bump();
2178                     try!(self.expect(&token::Colon));
2179                     if self.eat_keyword(keywords::While) {
2180                         return self.parse_while_expr(Some(lifetime), lo, attrs)
2181                     }
2182                     if self.eat_keyword(keywords::For) {
2183                         return self.parse_for_expr(Some(lifetime), lo, attrs)
2184                     }
2185                     if self.eat_keyword(keywords::Loop) {
2186                         return self.parse_loop_expr(Some(lifetime), lo, attrs)
2187                     }
2188                     return Err(self.fatal("expected `while`, `for`, or `loop` after a label"))
2189                 }
2190                 if self.eat_keyword(keywords::Loop) {
2191                     let lo = self.last_span.lo;
2192                     return self.parse_loop_expr(None, lo, attrs);
2193                 }
2194                 if self.eat_keyword(keywords::Continue) {
2195                     let ex = if self.token.is_lifetime() {
2196                         let ex = ExprAgain(Some(Spanned{
2197                             node: self.get_lifetime(),
2198                             span: self.span
2199                         }));
2200                         self.bump();
2201                         ex
2202                     } else {
2203                         ExprAgain(None)
2204                     };
2205                     let hi = self.last_span.hi;
2206                     return Ok(self.mk_expr(lo, hi, ex, attrs));
2207                 }
2208                 if self.eat_keyword(keywords::Match) {
2209                     return self.parse_match_expr(attrs);
2210                 }
2211                 if self.eat_keyword(keywords::Unsafe) {
2212                     return self.parse_block_expr(
2213                         lo,
2214                         UnsafeBlock(ast::UserProvided),
2215                         attrs);
2216                 }
2217                 if self.eat_keyword(keywords::Return) {
2218                     if self.token.can_begin_expr() {
2219                         let e = try!(self.parse_expr());
2220                         hi = e.span.hi;
2221                         ex = ExprRet(Some(e));
2222                     } else {
2223                         ex = ExprRet(None);
2224                     }
2225                 } else if self.eat_keyword(keywords::Break) {
2226                     if self.token.is_lifetime() {
2227                         ex = ExprBreak(Some(Spanned {
2228                             node: self.get_lifetime(),
2229                             span: self.span
2230                         }));
2231                         self.bump();
2232                     } else {
2233                         ex = ExprBreak(None);
2234                     }
2235                     hi = self.last_span.hi;
2236                 } else if self.check(&token::ModSep) ||
2237                         self.token.is_ident() &&
2238                         !self.check_keyword(keywords::True) &&
2239                         !self.check_keyword(keywords::False) {
2240                     let pth =
2241                         try!(self.parse_path(LifetimeAndTypesWithColons));
2242
2243                     // `!`, as an operator, is prefix, so we know this isn't that
2244                     if self.check(&token::Not) {
2245                         // MACRO INVOCATION expression
2246                         self.bump();
2247
2248                         let delim = try!(self.expect_open_delim());
2249                         let tts = try!(self.parse_seq_to_end(
2250                             &token::CloseDelim(delim),
2251                             seq_sep_none(),
2252                             |p| p.parse_token_tree()));
2253                         let hi = self.last_span.hi;
2254
2255                         return Ok(self.mk_mac_expr(lo,
2256                                                    hi,
2257                                                    Mac_ { path: pth, tts: tts, ctxt: EMPTY_CTXT },
2258                                                    attrs));
2259                     }
2260                     if self.check(&token::OpenDelim(token::Brace)) {
2261                         // This is a struct literal, unless we're prohibited
2262                         // from parsing struct literals here.
2263                         let prohibited = self.restrictions.contains(
2264                             Restrictions::RESTRICTION_NO_STRUCT_LITERAL
2265                         );
2266                         if !prohibited {
2267                             // It's a struct literal.
2268                             self.bump();
2269                             let mut fields = Vec::new();
2270                             let mut base = None;
2271
2272                             let attrs = attrs.append(
2273                                 try!(self.parse_inner_attributes())
2274                                     .into_thin_attrs());
2275
2276                             while self.token != token::CloseDelim(token::Brace) {
2277                                 if self.eat(&token::DotDot) {
2278                                     base = Some(try!(self.parse_expr()));
2279                                     break;
2280                                 }
2281
2282                                 fields.push(try!(self.parse_field()));
2283                                 try!(self.commit_expr(&*fields.last().unwrap().expr,
2284                                                  &[token::Comma],
2285                                                  &[token::CloseDelim(token::Brace)]));
2286                             }
2287
2288                             hi = self.span.hi;
2289                             try!(self.expect(&token::CloseDelim(token::Brace)));
2290                             ex = ExprStruct(pth, fields, base);
2291                             return Ok(self.mk_expr(lo, hi, ex, attrs));
2292                         }
2293                     }
2294
2295                     hi = pth.span.hi;
2296                     ex = ExprPath(None, pth);
2297                 } else {
2298                     // other literal expression
2299                     let lit = try!(self.parse_lit());
2300                     hi = lit.span.hi;
2301                     ex = ExprLit(P(lit));
2302                 }
2303             }
2304         }
2305
2306         return Ok(self.mk_expr(lo, hi, ex, attrs));
2307     }
2308
2309     fn parse_or_use_outer_attributes(&mut self,
2310                                      already_parsed_attrs: Option<ThinAttributes>)
2311                                      -> PResult<'a, ThinAttributes> {
2312         if let Some(attrs) = already_parsed_attrs {
2313             Ok(attrs)
2314         } else {
2315             self.parse_outer_attributes().map(|a| a.into_thin_attrs())
2316         }
2317     }
2318
2319     /// Parse a block or unsafe block
2320     pub fn parse_block_expr(&mut self, lo: BytePos, blk_mode: BlockCheckMode,
2321                             attrs: ThinAttributes)
2322                             -> PResult<'a, P<Expr>> {
2323
2324         let outer_attrs = attrs;
2325         try!(self.expect(&token::OpenDelim(token::Brace)));
2326
2327         let inner_attrs = try!(self.parse_inner_attributes()).into_thin_attrs();
2328         let attrs = outer_attrs.append(inner_attrs);
2329
2330         let blk = try!(self.parse_block_tail(lo, blk_mode));
2331         return Ok(self.mk_expr(blk.span.lo, blk.span.hi, ExprBlock(blk), attrs));
2332     }
2333
2334     /// parse a.b or a(13) or a[4] or just a
2335     pub fn parse_dot_or_call_expr(&mut self,
2336                                   already_parsed_attrs: Option<ThinAttributes>)
2337                                   -> PResult<'a, P<Expr>> {
2338         let attrs = try!(self.parse_or_use_outer_attributes(already_parsed_attrs));
2339
2340         let b = self.parse_bottom_expr();
2341         let (span, b) = try!(self.interpolated_or_expr_span(b));
2342         self.parse_dot_or_call_expr_with(b, span.lo, attrs)
2343     }
2344
2345     pub fn parse_dot_or_call_expr_with(&mut self,
2346                                        e0: P<Expr>,
2347                                        lo: BytePos,
2348                                        attrs: ThinAttributes)
2349                                        -> PResult<'a, P<Expr>> {
2350         // Stitch the list of outer attributes onto the return value.
2351         // A little bit ugly, but the best way given the current code
2352         // structure
2353         self.parse_dot_or_call_expr_with_(e0, lo)
2354         .map(|expr|
2355             expr.map(|mut expr| {
2356                 expr.attrs.update(|a| a.prepend(attrs));
2357                 match expr.node {
2358                     ExprIf(..) | ExprIfLet(..) => {
2359                         if !expr.attrs.as_attr_slice().is_empty() {
2360                             // Just point to the first attribute in there...
2361                             let span = expr.attrs.as_attr_slice()[0].span;
2362
2363                             self.span_err(span,
2364                                 "attributes are not yet allowed on `if` \
2365                                 expressions");
2366                         }
2367                     }
2368                     _ => {}
2369                 }
2370                 expr
2371             })
2372         )
2373     }
2374
2375     // Assuming we have just parsed `.foo` (i.e., a dot and an ident), continue
2376     // parsing into an expression.
2377     fn parse_dot_suffix(&mut self,
2378                         ident: Ident,
2379                         ident_span: Span,
2380                         self_value: P<Expr>,
2381                         lo: BytePos)
2382                         -> PResult<'a, P<Expr>> {
2383         let (_, tys, bindings) = if self.eat(&token::ModSep) {
2384             try!(self.expect_lt());
2385             try!(self.parse_generic_values_after_lt())
2386         } else {
2387             (Vec::new(), Vec::new(), Vec::new())
2388         };
2389
2390         if !bindings.is_empty() {
2391             let last_span = self.last_span;
2392             self.span_err(last_span, "type bindings are only permitted on trait paths");
2393         }
2394
2395         Ok(match self.token {
2396             // expr.f() method call.
2397             token::OpenDelim(token::Paren) => {
2398                 let mut es = try!(self.parse_unspanned_seq(
2399                     &token::OpenDelim(token::Paren),
2400                     &token::CloseDelim(token::Paren),
2401                     seq_sep_trailing_allowed(token::Comma),
2402                     |p| Ok(try!(p.parse_expr()))
2403                 ));
2404                 let hi = self.last_span.hi;
2405
2406                 es.insert(0, self_value);
2407                 let id = spanned(ident_span.lo, ident_span.hi, ident);
2408                 let nd = self.mk_method_call(id, tys, es);
2409                 self.mk_expr(lo, hi, nd, None)
2410             }
2411             // Field access.
2412             _ => {
2413                 if !tys.is_empty() {
2414                     let last_span = self.last_span;
2415                     self.span_err(last_span,
2416                                   "field expressions may not \
2417                                    have type parameters");
2418                 }
2419
2420                 let id = spanned(ident_span.lo, ident_span.hi, ident);
2421                 let field = self.mk_field(self_value, id);
2422                 self.mk_expr(lo, ident_span.hi, field, None)
2423             }
2424         })
2425     }
2426
2427     fn parse_dot_or_call_expr_with_(&mut self, e0: P<Expr>, lo: BytePos) -> PResult<'a, P<Expr>> {
2428         let mut e = e0;
2429         let mut hi;
2430         loop {
2431             // expr.f
2432             if self.eat(&token::Dot) {
2433                 match self.token {
2434                   token::Ident(i, _) => {
2435                     let dot_pos = self.last_span.hi;
2436                     hi = self.span.hi;
2437                     self.bump();
2438
2439                     e = try!(self.parse_dot_suffix(i, mk_sp(dot_pos, hi), e, lo));
2440                   }
2441                   token::Literal(token::Integer(n), suf) => {
2442                     let sp = self.span;
2443
2444                     // A tuple index may not have a suffix
2445                     self.expect_no_suffix(sp, "tuple index", suf);
2446
2447                     let dot = self.last_span.hi;
2448                     hi = self.span.hi;
2449                     self.bump();
2450
2451                     let index = n.as_str().parse::<usize>().ok();
2452                     match index {
2453                         Some(n) => {
2454                             let id = spanned(dot, hi, n);
2455                             let field = self.mk_tup_field(e, id);
2456                             e = self.mk_expr(lo, hi, field, None);
2457                         }
2458                         None => {
2459                             let last_span = self.last_span;
2460                             self.span_err(last_span, "invalid tuple or tuple struct index");
2461                         }
2462                     }
2463                   }
2464                   token::Literal(token::Float(n), _suf) => {
2465                     self.bump();
2466                     let last_span = self.last_span;
2467                     let fstr = n.as_str();
2468                     let mut err = self.diagnostic().struct_span_err(last_span,
2469                         &format!("unexpected token: `{}`", n.as_str()));
2470                     if fstr.chars().all(|x| "0123456789.".contains(x)) {
2471                         let float = match fstr.parse::<f64>().ok() {
2472                             Some(f) => f,
2473                             None => continue,
2474                         };
2475                         err.fileline_help(last_span,
2476                             &format!("try parenthesizing the first index; e.g., `(foo.{}){}`",
2477                                     float.trunc() as usize,
2478                                     format!(".{}", fstr.splitn(2, ".").last().unwrap())));
2479                     }
2480                     err.emit();
2481                     self.abort_if_errors();
2482
2483                   }
2484                   _ => {
2485                     // FIXME Could factor this out into non_fatal_unexpected or something.
2486                     let actual = self.this_token_to_string();
2487                     self.span_err(self.span, &format!("unexpected token: `{}`", actual));
2488
2489                     let dot_pos = self.last_span.hi;
2490                     e = try!(self.parse_dot_suffix(special_idents::invalid,
2491                                                    mk_sp(dot_pos, dot_pos),
2492                                                    e, lo));
2493                   }
2494                 }
2495                 continue;
2496             }
2497             if self.expr_is_complete(&*e) { break; }
2498             match self.token {
2499               // expr(...)
2500               token::OpenDelim(token::Paren) => {
2501                 let es = try!(self.parse_unspanned_seq(
2502                     &token::OpenDelim(token::Paren),
2503                     &token::CloseDelim(token::Paren),
2504                     seq_sep_trailing_allowed(token::Comma),
2505                     |p| Ok(try!(p.parse_expr()))
2506                 ));
2507                 hi = self.last_span.hi;
2508
2509                 let nd = self.mk_call(e, es);
2510                 e = self.mk_expr(lo, hi, nd, None);
2511               }
2512
2513               // expr[...]
2514               // Could be either an index expression or a slicing expression.
2515               token::OpenDelim(token::Bracket) => {
2516                 self.bump();
2517                 let ix = try!(self.parse_expr());
2518                 hi = self.span.hi;
2519                 try!(self.commit_expr_expecting(&*ix, token::CloseDelim(token::Bracket)));
2520                 let index = self.mk_index(e, ix);
2521                 e = self.mk_expr(lo, hi, index, None)
2522               }
2523               _ => return Ok(e)
2524             }
2525         }
2526         return Ok(e);
2527     }
2528
2529     // Parse unquoted tokens after a `$` in a token tree
2530     fn parse_unquoted(&mut self) -> PResult<'a, TokenTree> {
2531         let mut sp = self.span;
2532         let (name, namep) = match self.token {
2533             token::Dollar => {
2534                 self.bump();
2535
2536                 if self.token == token::OpenDelim(token::Paren) {
2537                     let Spanned { node: seq, span: seq_span } = try!(self.parse_seq(
2538                         &token::OpenDelim(token::Paren),
2539                         &token::CloseDelim(token::Paren),
2540                         seq_sep_none(),
2541                         |p| p.parse_token_tree()
2542                     ));
2543                     let (sep, repeat) = try!(self.parse_sep_and_kleene_op());
2544                     let name_num = macro_parser::count_names(&seq);
2545                     return Ok(TokenTree::Sequence(mk_sp(sp.lo, seq_span.hi),
2546                                       Rc::new(SequenceRepetition {
2547                                           tts: seq,
2548                                           separator: sep,
2549                                           op: repeat,
2550                                           num_captures: name_num
2551                                       })));
2552                 } else if self.token.is_keyword_allow_following_colon(keywords::Crate) {
2553                     self.bump();
2554                     return Ok(TokenTree::Token(sp, SpecialVarNt(SpecialMacroVar::CrateMacroVar)));
2555                 } else {
2556                     sp = mk_sp(sp.lo, self.span.hi);
2557                     let namep = match self.token { token::Ident(_, p) => p, _ => token::Plain };
2558                     let name = try!(self.parse_ident());
2559                     (name, namep)
2560                 }
2561             }
2562             token::SubstNt(name, namep) => {
2563                 self.bump();
2564                 (name, namep)
2565             }
2566             _ => unreachable!()
2567         };
2568         // continue by trying to parse the `:ident` after `$name`
2569         if self.token == token::Colon && self.look_ahead(1, |t| t.is_ident() &&
2570                                                                 !t.is_strict_keyword() &&
2571                                                                 !t.is_reserved_keyword()) {
2572             self.bump();
2573             sp = mk_sp(sp.lo, self.span.hi);
2574             let kindp = match self.token { token::Ident(_, p) => p, _ => token::Plain };
2575             let nt_kind = try!(self.parse_ident());
2576             Ok(TokenTree::Token(sp, MatchNt(name, nt_kind, namep, kindp)))
2577         } else {
2578             Ok(TokenTree::Token(sp, SubstNt(name, namep)))
2579         }
2580     }
2581
2582     pub fn check_unknown_macro_variable(&mut self) {
2583         if self.quote_depth == 0 {
2584             match self.token {
2585                 token::SubstNt(name, _) =>
2586                     self.fatal(&format!("unknown macro variable `{}`", name)).emit(),
2587                 _ => {}
2588             }
2589         }
2590     }
2591
2592     /// Parse an optional separator followed by a Kleene-style
2593     /// repetition token (+ or *).
2594     pub fn parse_sep_and_kleene_op(&mut self)
2595                                    -> PResult<'a, (Option<token::Token>, ast::KleeneOp)> {
2596         fn parse_kleene_op<'a>(parser: &mut Parser<'a>) -> PResult<'a,  Option<ast::KleeneOp>> {
2597             match parser.token {
2598                 token::BinOp(token::Star) => {
2599                     parser.bump();
2600                     Ok(Some(ast::ZeroOrMore))
2601                 },
2602                 token::BinOp(token::Plus) => {
2603                     parser.bump();
2604                     Ok(Some(ast::OneOrMore))
2605                 },
2606                 _ => Ok(None)
2607             }
2608         };
2609
2610         match try!(parse_kleene_op(self)) {
2611             Some(kleene_op) => return Ok((None, kleene_op)),
2612             None => {}
2613         }
2614
2615         let separator = self.bump_and_get();
2616         match try!(parse_kleene_op(self)) {
2617             Some(zerok) => Ok((Some(separator), zerok)),
2618             None => return Err(self.fatal("expected `*` or `+`"))
2619         }
2620     }
2621
2622     /// parse a single token tree from the input.
2623     pub fn parse_token_tree(&mut self) -> PResult<'a, TokenTree> {
2624         // FIXME #6994: currently, this is too eager. It
2625         // parses token trees but also identifies TokenType::Sequence's
2626         // and token::SubstNt's; it's too early to know yet
2627         // whether something will be a nonterminal or a seq
2628         // yet.
2629         maybe_whole!(deref self, NtTT);
2630
2631         // this is the fall-through for the 'match' below.
2632         // invariants: the current token is not a left-delimiter,
2633         // not an EOF, and not the desired right-delimiter (if
2634         // it were, parse_seq_to_before_end would have prevented
2635         // reaching this point.
2636         fn parse_non_delim_tt_tok<'b>(p: &mut Parser<'b>) -> PResult<'b,  TokenTree> {
2637             maybe_whole!(deref p, NtTT);
2638             match p.token {
2639                 token::CloseDelim(_) => {
2640                     let token_str = p.this_token_to_string();
2641                     let mut err = p.fatal(
2642                         &format!("incorrect close delimiter: `{}`", token_str));
2643                     // This is a conservative error: only report the last unclosed delimiter. The
2644                     // previous unclosed delimiters could actually be closed! The parser just hasn't
2645                     // gotten to them yet.
2646                     if let Some(&sp) = p.open_braces.last() {
2647                         err.span_note(sp, "unclosed delimiter");
2648                     };
2649                     Err(err)
2650                 },
2651                 /* we ought to allow different depths of unquotation */
2652                 token::Dollar | token::SubstNt(..) if p.quote_depth > 0 => {
2653                     p.parse_unquoted()
2654                 }
2655                 _ => {
2656                     Ok(TokenTree::Token(p.span, p.bump_and_get()))
2657                 }
2658             }
2659         }
2660
2661         match self.token {
2662             token::Eof => {
2663                 let open_braces = self.open_braces.clone();
2664                 let mut err: DiagnosticBuilder<'a> =
2665                     self.fatal("this file contains an un-closed delimiter");
2666                 for sp in &open_braces {
2667                     err.span_help(*sp, "did you mean to close this delimiter?");
2668                 }
2669                 return Err(err);
2670             },
2671             token::OpenDelim(delim) => {
2672                 // The span for beginning of the delimited section
2673                 let pre_span = self.span;
2674
2675                 // Parse the open delimiter.
2676                 self.open_braces.push(self.span);
2677                 let open_span = self.span;
2678                 self.bump();
2679
2680                 // Parse the token trees within the delimiters
2681                 let tts = try!(self.parse_seq_to_before_end(
2682                     &token::CloseDelim(delim),
2683                     seq_sep_none(),
2684                     |p| p.parse_token_tree()
2685                 ));
2686
2687                 // Parse the close delimiter.
2688                 let close_span = self.span;
2689                 self.bump();
2690                 self.open_braces.pop().unwrap();
2691
2692                 // Expand to cover the entire delimited token tree
2693                 let span = Span { hi: close_span.hi, ..pre_span };
2694
2695                 Ok(TokenTree::Delimited(span, Rc::new(Delimited {
2696                     delim: delim,
2697                     open_span: open_span,
2698                     tts: tts,
2699                     close_span: close_span,
2700                 })))
2701             },
2702             _ => parse_non_delim_tt_tok(self),
2703         }
2704     }
2705
2706     // parse a stream of tokens into a list of TokenTree's,
2707     // up to EOF.
2708     pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> {
2709         let mut tts = Vec::new();
2710         while self.token != token::Eof {
2711             tts.push(try!(self.parse_token_tree()));
2712         }
2713         Ok(tts)
2714     }
2715
2716     /// Parse a prefix-unary-operator expr
2717     pub fn parse_prefix_expr(&mut self,
2718                              already_parsed_attrs: Option<ThinAttributes>)
2719                              -> PResult<'a, P<Expr>> {
2720         let attrs = try!(self.parse_or_use_outer_attributes(already_parsed_attrs));
2721         let lo = self.span.lo;
2722         let hi;
2723         // Note: when adding new unary operators, don't forget to adjust Token::can_begin_expr()
2724         let ex = match self.token {
2725             token::Not => {
2726                 self.bump();
2727                 let e = self.parse_prefix_expr(None);
2728                 let (span, e) = try!(self.interpolated_or_expr_span(e));
2729                 hi = span.hi;
2730                 self.mk_unary(UnNot, e)
2731             }
2732             token::BinOp(token::Minus) => {
2733                 self.bump();
2734                 let e = self.parse_prefix_expr(None);
2735                 let (span, e) = try!(self.interpolated_or_expr_span(e));
2736                 hi = span.hi;
2737                 self.mk_unary(UnNeg, e)
2738             }
2739             token::BinOp(token::Star) => {
2740                 self.bump();
2741                 let e = self.parse_prefix_expr(None);
2742                 let (span, e) = try!(self.interpolated_or_expr_span(e));
2743                 hi = span.hi;
2744                 self.mk_unary(UnDeref, e)
2745             }
2746             token::BinOp(token::And) | token::AndAnd => {
2747                 try!(self.expect_and());
2748                 let m = try!(self.parse_mutability());
2749                 let e = self.parse_prefix_expr(None);
2750                 let (span, e) = try!(self.interpolated_or_expr_span(e));
2751                 hi = span.hi;
2752                 ExprAddrOf(m, e)
2753             }
2754             token::Ident(..) if self.token.is_keyword(keywords::In) => {
2755                 self.bump();
2756                 let place = try!(self.parse_expr_res(
2757                     Restrictions::RESTRICTION_NO_STRUCT_LITERAL,
2758                     None,
2759                 ));
2760                 let blk = try!(self.parse_block());
2761                 let span = blk.span;
2762                 hi = span.hi;
2763                 let blk_expr = self.mk_expr(span.lo, span.hi, ExprBlock(blk),
2764                                             None);
2765                 ExprInPlace(place, blk_expr)
2766             }
2767             token::Ident(..) if self.token.is_keyword(keywords::Box) => {
2768                 self.bump();
2769                 let e = self.parse_prefix_expr(None);
2770                 let (span, e) = try!(self.interpolated_or_expr_span(e));
2771                 hi = span.hi;
2772                 ExprBox(e)
2773             }
2774             _ => return self.parse_dot_or_call_expr(Some(attrs))
2775         };
2776         return Ok(self.mk_expr(lo, hi, ex, attrs));
2777     }
2778
2779     /// Parse an associative expression
2780     ///
2781     /// This parses an expression accounting for associativity and precedence of the operators in
2782     /// the expression.
2783     pub fn parse_assoc_expr(&mut self,
2784                             already_parsed_attrs: Option<ThinAttributes>)
2785                             -> PResult<'a, P<Expr>> {
2786         self.parse_assoc_expr_with(0, already_parsed_attrs.into())
2787     }
2788
2789     /// Parse an associative expression with operators of at least `min_prec` precedence
2790     pub fn parse_assoc_expr_with(&mut self,
2791                                  min_prec: usize,
2792                                  lhs: LhsExpr)
2793                                  -> PResult<'a, P<Expr>> {
2794         let mut lhs = if let LhsExpr::AlreadyParsed(expr) = lhs {
2795             expr
2796         } else {
2797             let attrs = match lhs {
2798                 LhsExpr::AttributesParsed(attrs) => Some(attrs),
2799                 _ => None,
2800             };
2801             if self.token == token::DotDot {
2802                 return self.parse_prefix_range_expr(attrs);
2803             } else {
2804                 try!(self.parse_prefix_expr(attrs))
2805             }
2806         };
2807
2808
2809         if self.expr_is_complete(&*lhs) {
2810             // Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071
2811             return Ok(lhs);
2812         }
2813         self.expected_tokens.push(TokenType::Operator);
2814         while let Some(op) = AssocOp::from_token(&self.token) {
2815
2816             let lhs_span = if self.last_token_interpolated {
2817                 self.last_span
2818             } else {
2819                 lhs.span
2820             };
2821
2822             let cur_op_span = self.span;
2823             let restrictions = if op.is_assign_like() {
2824                 self.restrictions & Restrictions::RESTRICTION_NO_STRUCT_LITERAL
2825             } else {
2826                 self.restrictions
2827             };
2828             if op.precedence() < min_prec {
2829                 break;
2830             }
2831             self.bump();
2832             if op.is_comparison() {
2833                 self.check_no_chained_comparison(&*lhs, &op);
2834             }
2835             // Special cases:
2836             if op == AssocOp::As {
2837                 let rhs = try!(self.parse_ty());
2838                 lhs = self.mk_expr(lhs_span.lo, rhs.span.hi,
2839                                    ExprCast(lhs, rhs), None);
2840                 continue
2841             } else if op == AssocOp::Colon {
2842                 let rhs = try!(self.parse_ty());
2843                 lhs = self.mk_expr(lhs_span.lo, rhs.span.hi,
2844                                    ExprType(lhs, rhs), None);
2845                 continue
2846             } else if op == AssocOp::DotDot {
2847                     // If we didn’t have to handle `x..`, it would be pretty easy to generalise
2848                     // it to the Fixity::None code.
2849                     //
2850                     // We have 2 alternatives here: `x..y` and `x..` The other two variants are
2851                     // handled with `parse_prefix_range_expr` call above.
2852                     let rhs = if self.is_at_start_of_range_notation_rhs() {
2853                         let rhs = self.parse_assoc_expr_with(op.precedence() + 1,
2854                                                              LhsExpr::NotYetParsed);
2855                         match rhs {
2856                             Ok(e) => Some(e),
2857                             Err(mut e) => {
2858                                 e.cancel();
2859                                 None
2860                             }
2861                         }
2862                     } else {
2863                         None
2864                     };
2865                     let (lhs_span, rhs_span) = (lhs_span, if let Some(ref x) = rhs {
2866                         x.span
2867                     } else {
2868                         cur_op_span
2869                     });
2870                     let r = self.mk_range(Some(lhs), rhs);
2871                     lhs = self.mk_expr(lhs_span.lo, rhs_span.hi, r, None);
2872                     break
2873             }
2874
2875             let rhs = try!(match op.fixity() {
2876                 Fixity::Right => self.with_res(
2877                     restrictions - Restrictions::RESTRICTION_STMT_EXPR,
2878                     |this| {
2879                         this.parse_assoc_expr_with(op.precedence(),
2880                             LhsExpr::NotYetParsed)
2881                 }),
2882                 Fixity::Left => self.with_res(
2883                     restrictions - Restrictions::RESTRICTION_STMT_EXPR,
2884                     |this| {
2885                         this.parse_assoc_expr_with(op.precedence() + 1,
2886                             LhsExpr::NotYetParsed)
2887                 }),
2888                 // We currently have no non-associative operators that are not handled above by
2889                 // the special cases. The code is here only for future convenience.
2890                 Fixity::None => self.with_res(
2891                     restrictions - Restrictions::RESTRICTION_STMT_EXPR,
2892                     |this| {
2893                         this.parse_assoc_expr_with(op.precedence() + 1,
2894                             LhsExpr::NotYetParsed)
2895                 }),
2896             });
2897
2898             lhs = match op {
2899                 AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide |
2900                 AssocOp::Modulus | AssocOp::LAnd | AssocOp::LOr | AssocOp::BitXor |
2901                 AssocOp::BitAnd | AssocOp::BitOr | AssocOp::ShiftLeft | AssocOp::ShiftRight |
2902                 AssocOp::Equal | AssocOp::Less | AssocOp::LessEqual | AssocOp::NotEqual |
2903                 AssocOp::Greater | AssocOp::GreaterEqual => {
2904                     let ast_op = op.to_ast_binop().unwrap();
2905                     let (lhs_span, rhs_span) = (lhs_span, rhs.span);
2906                     let binary = self.mk_binary(codemap::respan(cur_op_span, ast_op), lhs, rhs);
2907                     self.mk_expr(lhs_span.lo, rhs_span.hi, binary, None)
2908                 }
2909                 AssocOp::Assign =>
2910                     self.mk_expr(lhs_span.lo, rhs.span.hi, ExprAssign(lhs, rhs), None),
2911                 AssocOp::Inplace =>
2912                     self.mk_expr(lhs_span.lo, rhs.span.hi, ExprInPlace(lhs, rhs), None),
2913                 AssocOp::AssignOp(k) => {
2914                     let aop = match k {
2915                         token::Plus =>    BiAdd,
2916                         token::Minus =>   BiSub,
2917                         token::Star =>    BiMul,
2918                         token::Slash =>   BiDiv,
2919                         token::Percent => BiRem,
2920                         token::Caret =>   BiBitXor,
2921                         token::And =>     BiBitAnd,
2922                         token::Or =>      BiBitOr,
2923                         token::Shl =>     BiShl,
2924                         token::Shr =>     BiShr
2925                     };
2926                     let (lhs_span, rhs_span) = (lhs_span, rhs.span);
2927                     let aopexpr = self.mk_assign_op(codemap::respan(cur_op_span, aop), lhs, rhs);
2928                     self.mk_expr(lhs_span.lo, rhs_span.hi, aopexpr, None)
2929                 }
2930                 AssocOp::As | AssocOp::Colon | AssocOp::DotDot => {
2931                     self.bug("As, Colon or DotDot branch reached")
2932                 }
2933             };
2934
2935             if op.fixity() == Fixity::None { break }
2936         }
2937         Ok(lhs)
2938     }
2939
2940     /// Produce an error if comparison operators are chained (RFC #558).
2941     /// We only need to check lhs, not rhs, because all comparison ops
2942     /// have same precedence and are left-associative
2943     fn check_no_chained_comparison(&mut self, lhs: &Expr, outer_op: &AssocOp) {
2944         debug_assert!(outer_op.is_comparison());
2945         match lhs.node {
2946             ExprBinary(op, _, _) if op.node.is_comparison() => {
2947                 // respan to include both operators
2948                 let op_span = mk_sp(op.span.lo, self.span.hi);
2949                 let mut err = self.diagnostic().struct_span_err(op_span,
2950                     "chained comparison operators require parentheses");
2951                 if op.node == BiLt && *outer_op == AssocOp::Greater {
2952                     err.fileline_help(op_span,
2953                         "use `::<...>` instead of `<...>` if you meant to specify type arguments");
2954                 }
2955                 err.emit();
2956             }
2957             _ => {}
2958         }
2959     }
2960
2961     /// Parse prefix-forms of range notation: `..expr` and `..`
2962     fn parse_prefix_range_expr(&mut self,
2963                                already_parsed_attrs: Option<ThinAttributes>)
2964                                -> PResult<'a, P<Expr>> {
2965         debug_assert!(self.token == token::DotDot);
2966         let attrs = try!(self.parse_or_use_outer_attributes(already_parsed_attrs));
2967         let lo = self.span.lo;
2968         let mut hi = self.span.hi;
2969         self.bump();
2970         let opt_end = if self.is_at_start_of_range_notation_rhs() {
2971             // RHS must be parsed with more associativity than DotDot.
2972             let next_prec = AssocOp::from_token(&token::DotDot).unwrap().precedence() + 1;
2973             Some(try!(self.parse_assoc_expr_with(next_prec,
2974                                                  LhsExpr::NotYetParsed)
2975             .map(|x|{
2976                 hi = x.span.hi;
2977                 x
2978             })))
2979          } else {
2980             None
2981         };
2982         let r = self.mk_range(None, opt_end);
2983         Ok(self.mk_expr(lo, hi, r, attrs))
2984     }
2985
2986     fn is_at_start_of_range_notation_rhs(&self) -> bool {
2987         if self.token.can_begin_expr() {
2988             // parse `for i in 1.. { }` as infinite loop, not as `for i in (1..{})`.
2989             if self.token == token::OpenDelim(token::Brace) {
2990                 return !self.restrictions.contains(Restrictions::RESTRICTION_NO_STRUCT_LITERAL);
2991             }
2992             true
2993         } else {
2994             false
2995         }
2996     }
2997
2998     /// Parse an 'if' or 'if let' expression ('if' token already eaten)
2999     pub fn parse_if_expr(&mut self, attrs: ThinAttributes) -> PResult<'a, P<Expr>> {
3000         if self.check_keyword(keywords::Let) {
3001             return self.parse_if_let_expr(attrs);
3002         }
3003         let lo = self.last_span.lo;
3004         let cond = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None));
3005         let thn = try!(self.parse_block());
3006         let mut els: Option<P<Expr>> = None;
3007         let mut hi = thn.span.hi;
3008         if self.eat_keyword(keywords::Else) {
3009             let elexpr = try!(self.parse_else_expr());
3010             hi = elexpr.span.hi;
3011             els = Some(elexpr);
3012         }
3013         Ok(self.mk_expr(lo, hi, ExprIf(cond, thn, els), attrs))
3014     }
3015
3016     /// Parse an 'if let' expression ('if' token already eaten)
3017     pub fn parse_if_let_expr(&mut self, attrs: ThinAttributes)
3018                              -> PResult<'a, P<Expr>> {
3019         let lo = self.last_span.lo;
3020         try!(self.expect_keyword(keywords::Let));
3021         let pat = try!(self.parse_pat());
3022         try!(self.expect(&token::Eq));
3023         let expr = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None));
3024         let thn = try!(self.parse_block());
3025         let (hi, els) = if self.eat_keyword(keywords::Else) {
3026             let expr = try!(self.parse_else_expr());
3027             (expr.span.hi, Some(expr))
3028         } else {
3029             (thn.span.hi, None)
3030         };
3031         Ok(self.mk_expr(lo, hi, ExprIfLet(pat, expr, thn, els), attrs))
3032     }
3033
3034     // `|args| expr`
3035     pub fn parse_lambda_expr(&mut self, lo: BytePos,
3036                              capture_clause: CaptureClause,
3037                              attrs: ThinAttributes)
3038                              -> PResult<'a, P<Expr>>
3039     {
3040         let decl = try!(self.parse_fn_block_decl());
3041         let body = match decl.output {
3042             DefaultReturn(_) => {
3043                 // If no explicit return type is given, parse any
3044                 // expr and wrap it up in a dummy block:
3045                 let body_expr = try!(self.parse_expr());
3046                 P(ast::Block {
3047                     id: ast::DUMMY_NODE_ID,
3048                     stmts: vec![],
3049                     span: body_expr.span,
3050                     expr: Some(body_expr),
3051                     rules: DefaultBlock,
3052                 })
3053             }
3054             _ => {
3055                 // If an explicit return type is given, require a
3056                 // block to appear (RFC 968).
3057                 try!(self.parse_block())
3058             }
3059         };
3060
3061         Ok(self.mk_expr(
3062             lo,
3063             body.span.hi,
3064             ExprClosure(capture_clause, decl, body), attrs))
3065     }
3066
3067     // `else` token already eaten
3068     pub fn parse_else_expr(&mut self) -> PResult<'a, P<Expr>> {
3069         if self.eat_keyword(keywords::If) {
3070             return self.parse_if_expr(None);
3071         } else {
3072             let blk = try!(self.parse_block());
3073             return Ok(self.mk_expr(blk.span.lo, blk.span.hi, ExprBlock(blk), None));
3074         }
3075     }
3076
3077     /// Parse a 'for' .. 'in' expression ('for' token already eaten)
3078     pub fn parse_for_expr(&mut self, opt_ident: Option<ast::Ident>,
3079                           span_lo: BytePos,
3080                           attrs: ThinAttributes) -> PResult<'a, P<Expr>> {
3081         // Parse: `for <src_pat> in <src_expr> <src_loop_block>`
3082
3083         let pat = try!(self.parse_pat());
3084         try!(self.expect_keyword(keywords::In));
3085         let expr = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None));
3086         let (iattrs, loop_block) = try!(self.parse_inner_attrs_and_block());
3087         let attrs = attrs.append(iattrs.into_thin_attrs());
3088
3089         let hi = self.last_span.hi;
3090
3091         Ok(self.mk_expr(span_lo, hi,
3092                         ExprForLoop(pat, expr, loop_block, opt_ident),
3093                         attrs))
3094     }
3095
3096     /// Parse a 'while' or 'while let' expression ('while' token already eaten)
3097     pub fn parse_while_expr(&mut self, opt_ident: Option<ast::Ident>,
3098                             span_lo: BytePos,
3099                             attrs: ThinAttributes) -> PResult<'a, P<Expr>> {
3100         if self.token.is_keyword(keywords::Let) {
3101             return self.parse_while_let_expr(opt_ident, span_lo, attrs);
3102         }
3103         let cond = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None));
3104         let (iattrs, body) = try!(self.parse_inner_attrs_and_block());
3105         let attrs = attrs.append(iattrs.into_thin_attrs());
3106         let hi = body.span.hi;
3107         return Ok(self.mk_expr(span_lo, hi, ExprWhile(cond, body, opt_ident),
3108                                attrs));
3109     }
3110
3111     /// Parse a 'while let' expression ('while' token already eaten)
3112     pub fn parse_while_let_expr(&mut self, opt_ident: Option<ast::Ident>,
3113                                 span_lo: BytePos,
3114                                 attrs: ThinAttributes) -> PResult<'a, P<Expr>> {
3115         try!(self.expect_keyword(keywords::Let));
3116         let pat = try!(self.parse_pat());
3117         try!(self.expect(&token::Eq));
3118         let expr = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None));
3119         let (iattrs, body) = try!(self.parse_inner_attrs_and_block());
3120         let attrs = attrs.append(iattrs.into_thin_attrs());
3121         let hi = body.span.hi;
3122         return Ok(self.mk_expr(span_lo, hi, ExprWhileLet(pat, expr, body, opt_ident), attrs));
3123     }
3124
3125     // parse `loop {...}`, `loop` token already eaten
3126     pub fn parse_loop_expr(&mut self, opt_ident: Option<ast::Ident>,
3127                            span_lo: BytePos,
3128                            attrs: ThinAttributes) -> PResult<'a, P<Expr>> {
3129         let (iattrs, body) = try!(self.parse_inner_attrs_and_block());
3130         let attrs = attrs.append(iattrs.into_thin_attrs());
3131         let hi = body.span.hi;
3132         Ok(self.mk_expr(span_lo, hi, ExprLoop(body, opt_ident), attrs))
3133     }
3134
3135     // `match` token already eaten
3136     fn parse_match_expr(&mut self, attrs: ThinAttributes) -> PResult<'a, P<Expr>> {
3137         let match_span = self.last_span;
3138         let lo = self.last_span.lo;
3139         let discriminant = try!(self.parse_expr_res(
3140             Restrictions::RESTRICTION_NO_STRUCT_LITERAL, None));
3141         if let Err(mut e) = self.commit_expr_expecting(&*discriminant,
3142                                                        token::OpenDelim(token::Brace)) {
3143             if self.token == token::Token::Semi {
3144                 e.span_note(match_span, "did you mean to remove this `match` keyword?");
3145             }
3146             return Err(e)
3147         }
3148         let attrs = attrs.append(
3149             try!(self.parse_inner_attributes()).into_thin_attrs());
3150         let mut arms: Vec<Arm> = Vec::new();
3151         while self.token != token::CloseDelim(token::Brace) {
3152             arms.push(try!(self.parse_arm()));
3153         }
3154         let hi = self.span.hi;
3155         self.bump();
3156         return Ok(self.mk_expr(lo, hi, ExprMatch(discriminant, arms), attrs));
3157     }
3158
3159     pub fn parse_arm(&mut self) -> PResult<'a, Arm> {
3160         maybe_whole!(no_clone self, NtArm);
3161
3162         let attrs = try!(self.parse_outer_attributes());
3163         let pats = try!(self.parse_pats());
3164         let mut guard = None;
3165         if self.eat_keyword(keywords::If) {
3166             guard = Some(try!(self.parse_expr()));
3167         }
3168         try!(self.expect(&token::FatArrow));
3169         let expr = try!(self.parse_expr_res(Restrictions::RESTRICTION_STMT_EXPR, None));
3170
3171         let require_comma =
3172             !classify::expr_is_simple_block(&*expr)
3173             && self.token != token::CloseDelim(token::Brace);
3174
3175         if require_comma {
3176             try!(self.commit_expr(&*expr, &[token::Comma], &[token::CloseDelim(token::Brace)]));
3177         } else {
3178             self.eat(&token::Comma);
3179         }
3180
3181         Ok(ast::Arm {
3182             attrs: attrs,
3183             pats: pats,
3184             guard: guard,
3185             body: expr,
3186         })
3187     }
3188
3189     /// Parse an expression
3190     pub fn parse_expr(&mut self) -> PResult<'a, P<Expr>> {
3191         self.parse_expr_res(Restrictions::empty(), None)
3192     }
3193
3194     /// Evaluate the closure with restrictions in place.
3195     ///
3196     /// After the closure is evaluated, restrictions are reset.
3197     pub fn with_res<F>(&mut self, r: Restrictions, f: F) -> PResult<'a, P<Expr>>
3198         where F: FnOnce(&mut Self) -> PResult<'a,  P<Expr>>
3199     {
3200         let old = self.restrictions;
3201         self.restrictions = r;
3202         let r = f(self);
3203         self.restrictions = old;
3204         return r;
3205
3206     }
3207
3208     /// Parse an expression, subject to the given restrictions
3209     pub fn parse_expr_res(&mut self, r: Restrictions,
3210                           already_parsed_attrs: Option<ThinAttributes>)
3211                           -> PResult<'a, P<Expr>> {
3212         self.with_res(r, |this| this.parse_assoc_expr(already_parsed_attrs))
3213     }
3214
3215     /// Parse the RHS of a local variable declaration (e.g. '= 14;')
3216     fn parse_initializer(&mut self) -> PResult<'a, Option<P<Expr>>> {
3217         if self.check(&token::Eq) {
3218             self.bump();
3219             Ok(Some(try!(self.parse_expr())))
3220         } else {
3221             Ok(None)
3222         }
3223     }
3224
3225     /// Parse patterns, separated by '|' s
3226     fn parse_pats(&mut self) -> PResult<'a, Vec<P<Pat>>> {
3227         let mut pats = Vec::new();
3228         loop {
3229             pats.push(try!(self.parse_pat()));
3230             if self.check(&token::BinOp(token::Or)) { self.bump();}
3231             else { return Ok(pats); }
3232         };
3233     }
3234
3235     fn parse_pat_tuple_elements(&mut self) -> PResult<'a, Vec<P<Pat>>> {
3236         let mut fields = vec![];
3237         if !self.check(&token::CloseDelim(token::Paren)) {
3238             fields.push(try!(self.parse_pat()));
3239             if self.look_ahead(1, |t| *t != token::CloseDelim(token::Paren)) {
3240                 while self.eat(&token::Comma) &&
3241                       !self.check(&token::CloseDelim(token::Paren)) {
3242                     fields.push(try!(self.parse_pat()));
3243                 }
3244             }
3245             if fields.len() == 1 {
3246                 try!(self.expect(&token::Comma));
3247             }
3248         }
3249         Ok(fields)
3250     }
3251
3252     fn parse_pat_vec_elements(
3253         &mut self,
3254     ) -> PResult<'a, (Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>)> {
3255         let mut before = Vec::new();
3256         let mut slice = None;
3257         let mut after = Vec::new();
3258         let mut first = true;
3259         let mut before_slice = true;
3260
3261         while self.token != token::CloseDelim(token::Bracket) {
3262             if first {
3263                 first = false;
3264             } else {
3265                 try!(self.expect(&token::Comma));
3266
3267                 if self.token == token::CloseDelim(token::Bracket)
3268                         && (before_slice || !after.is_empty()) {
3269                     break
3270                 }
3271             }
3272
3273             if before_slice {
3274                 if self.check(&token::DotDot) {
3275                     self.bump();
3276
3277                     if self.check(&token::Comma) ||
3278                             self.check(&token::CloseDelim(token::Bracket)) {
3279                         slice = Some(P(ast::Pat {
3280                             id: ast::DUMMY_NODE_ID,
3281                             node: PatWild,
3282                             span: self.span,
3283                         }));
3284                         before_slice = false;
3285                     }
3286                     continue
3287                 }
3288             }
3289
3290             let subpat = try!(self.parse_pat());
3291             if before_slice && self.check(&token::DotDot) {
3292                 self.bump();
3293                 slice = Some(subpat);
3294                 before_slice = false;
3295             } else if before_slice {
3296                 before.push(subpat);
3297             } else {
3298                 after.push(subpat);
3299             }
3300         }
3301
3302         Ok((before, slice, after))
3303     }
3304
3305     /// Parse the fields of a struct-like pattern
3306     fn parse_pat_fields(&mut self) -> PResult<'a, (Vec<codemap::Spanned<ast::FieldPat>> , bool)> {
3307         let mut fields = Vec::new();
3308         let mut etc = false;
3309         let mut first = true;
3310         while self.token != token::CloseDelim(token::Brace) {
3311             if first {
3312                 first = false;
3313             } else {
3314                 try!(self.expect(&token::Comma));
3315                 // accept trailing commas
3316                 if self.check(&token::CloseDelim(token::Brace)) { break }
3317             }
3318
3319             let lo = self.span.lo;
3320             let hi;
3321
3322             if self.check(&token::DotDot) {
3323                 self.bump();
3324                 if self.token != token::CloseDelim(token::Brace) {
3325                     let token_str = self.this_token_to_string();
3326                     return Err(self.fatal(&format!("expected `{}`, found `{}`", "}",
3327                                        token_str)))
3328                 }
3329                 etc = true;
3330                 break;
3331             }
3332
3333             // Check if a colon exists one ahead. This means we're parsing a fieldname.
3334             let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
3335                 // Parsing a pattern of the form "fieldname: pat"
3336                 let fieldname = try!(self.parse_ident());
3337                 self.bump();
3338                 let pat = try!(self.parse_pat());
3339                 hi = pat.span.hi;
3340                 (pat, fieldname, false)
3341             } else {
3342                 // Parsing a pattern of the form "(box) (ref) (mut) fieldname"
3343                 let is_box = self.eat_keyword(keywords::Box);
3344                 let boxed_span_lo = self.span.lo;
3345                 let is_ref = self.eat_keyword(keywords::Ref);
3346                 let is_mut = self.eat_keyword(keywords::Mut);
3347                 let fieldname = try!(self.parse_ident());
3348                 hi = self.last_span.hi;
3349
3350                 let bind_type = match (is_ref, is_mut) {
3351                     (true, true) => BindingMode::ByRef(MutMutable),
3352                     (true, false) => BindingMode::ByRef(MutImmutable),
3353                     (false, true) => BindingMode::ByValue(MutMutable),
3354                     (false, false) => BindingMode::ByValue(MutImmutable),
3355                 };
3356                 let fieldpath = codemap::Spanned{span:self.last_span, node:fieldname};
3357                 let fieldpat = P(ast::Pat{
3358                     id: ast::DUMMY_NODE_ID,
3359                     node: PatIdent(bind_type, fieldpath, None),
3360                     span: mk_sp(boxed_span_lo, hi),
3361                 });
3362
3363                 let subpat = if is_box {
3364                     P(ast::Pat{
3365                         id: ast::DUMMY_NODE_ID,
3366                         node: PatBox(fieldpat),
3367                         span: mk_sp(lo, hi),
3368                     })
3369                 } else {
3370                     fieldpat
3371                 };
3372                 (subpat, fieldname, true)
3373             };
3374
3375             fields.push(codemap::Spanned { span: mk_sp(lo, hi),
3376                                            node: ast::FieldPat { ident: fieldname,
3377                                                                  pat: subpat,
3378                                                                  is_shorthand: is_shorthand }});
3379         }
3380         return Ok((fields, etc));
3381     }
3382
3383     fn parse_pat_range_end(&mut self) -> PResult<'a, P<Expr>> {
3384         if self.is_path_start() {
3385             let lo = self.span.lo;
3386             let (qself, path) = if self.eat_lt() {
3387                 // Parse a qualified path
3388                 let (qself, path) =
3389                     try!(self.parse_qualified_path(NoTypesAllowed));
3390                 (Some(qself), path)
3391             } else {
3392                 // Parse an unqualified path
3393                 (None, try!(self.parse_path(LifetimeAndTypesWithColons)))
3394             };
3395             let hi = self.last_span.hi;
3396             Ok(self.mk_expr(lo, hi, ExprPath(qself, path), None))
3397         } else {
3398             self.parse_pat_literal_maybe_minus()
3399         }
3400     }
3401
3402     fn is_path_start(&self) -> bool {
3403         (self.token == token::Lt || self.token == token::ModSep
3404             || self.token.is_ident() || self.token.is_path())
3405             && !self.token.is_keyword(keywords::True) && !self.token.is_keyword(keywords::False)
3406     }
3407
3408     /// Parse a pattern.
3409     pub fn parse_pat(&mut self) -> PResult<'a, P<Pat>> {
3410         maybe_whole!(self, NtPat);
3411
3412         let lo = self.span.lo;
3413         let pat;
3414         match self.token {
3415           token::Underscore => {
3416             // Parse _
3417             self.bump();
3418             pat = PatWild;
3419           }
3420           token::BinOp(token::And) | token::AndAnd => {
3421             // Parse &pat / &mut pat
3422             try!(self.expect_and());
3423             let mutbl = try!(self.parse_mutability());
3424             if let token::Lifetime(ident) = self.token {
3425                 return Err(self.fatal(&format!("unexpected lifetime `{}` in pattern", ident)));
3426             }
3427
3428             let subpat = try!(self.parse_pat());
3429             pat = PatRegion(subpat, mutbl);
3430           }
3431           token::OpenDelim(token::Paren) => {
3432             // Parse (pat,pat,pat,...) as tuple pattern
3433             self.bump();
3434             let fields = try!(self.parse_pat_tuple_elements());
3435             try!(self.expect(&token::CloseDelim(token::Paren)));
3436             pat = PatTup(fields);
3437           }
3438           token::OpenDelim(token::Bracket) => {
3439             // Parse [pat,pat,...] as slice pattern
3440             self.bump();
3441             let (before, slice, after) = try!(self.parse_pat_vec_elements());
3442             try!(self.expect(&token::CloseDelim(token::Bracket)));
3443             pat = PatVec(before, slice, after);
3444           }
3445           _ => {
3446             // At this point, token != _, &, &&, (, [
3447             if self.eat_keyword(keywords::Mut) {
3448                 // Parse mut ident @ pat
3449                 pat = try!(self.parse_pat_ident(BindingMode::ByValue(MutMutable)));
3450             } else if self.eat_keyword(keywords::Ref) {
3451                 // Parse ref ident @ pat / ref mut ident @ pat
3452                 let mutbl = try!(self.parse_mutability());
3453                 pat = try!(self.parse_pat_ident(BindingMode::ByRef(mutbl)));
3454             } else if self.eat_keyword(keywords::Box) {
3455                 // Parse box pat
3456                 let subpat = try!(self.parse_pat());
3457                 pat = PatBox(subpat);
3458             } else if self.is_path_start() {
3459                 // Parse pattern starting with a path
3460                 if self.token.is_plain_ident() && self.look_ahead(1, |t| *t != token::DotDotDot &&
3461                         *t != token::OpenDelim(token::Brace) &&
3462                         *t != token::OpenDelim(token::Paren) &&
3463                         // Contrary to its definition, a plain ident can be followed by :: in macros
3464                         *t != token::ModSep) {
3465                     // Plain idents have some extra abilities here compared to general paths
3466                     if self.look_ahead(1, |t| *t == token::Not) {
3467                         // Parse macro invocation
3468                         let ident = try!(self.parse_ident());
3469                         let ident_span = self.last_span;
3470                         let path = ident_to_path(ident_span, ident);
3471                         self.bump();
3472                         let delim = try!(self.expect_open_delim());
3473                         let tts = try!(self.parse_seq_to_end(&token::CloseDelim(delim),
3474                                 seq_sep_none(), |p| p.parse_token_tree()));
3475                         let mac = Mac_ { path: path, tts: tts, ctxt: EMPTY_CTXT };
3476                         pat = PatMac(codemap::Spanned {node: mac,
3477                                                        span: mk_sp(lo, self.last_span.hi)});
3478                     } else {
3479                         // Parse ident @ pat
3480                         // This can give false positives and parse nullary enums,
3481                         // they are dealt with later in resolve
3482                         pat = try!(self.parse_pat_ident(BindingMode::ByValue(MutImmutable)));
3483                     }
3484                 } else {
3485                     let (qself, path) = if self.eat_lt() {
3486                         // Parse a qualified path
3487                         let (qself, path) =
3488                             try!(self.parse_qualified_path(NoTypesAllowed));
3489                         (Some(qself), path)
3490                     } else {
3491                         // Parse an unqualified path
3492                         (None, try!(self.parse_path(LifetimeAndTypesWithColons)))
3493                     };
3494                     match self.token {
3495                       token::DotDotDot => {
3496                         // Parse range
3497                         let hi = self.last_span.hi;
3498                         let begin = self.mk_expr(lo, hi, ExprPath(qself, path), None);
3499                         self.bump();
3500                         let end = try!(self.parse_pat_range_end());
3501                         pat = PatRange(begin, end);
3502                       }
3503                       token::OpenDelim(token::Brace) => {
3504                          if qself.is_some() {
3505                             return Err(self.fatal("unexpected `{` after qualified path"));
3506                         }
3507                         // Parse struct pattern
3508                         self.bump();
3509                         let (fields, etc) = try!(self.parse_pat_fields());
3510                         self.bump();
3511                         pat = PatStruct(path, fields, etc);
3512                       }
3513                       token::OpenDelim(token::Paren) => {
3514                         if qself.is_some() {
3515                             return Err(self.fatal("unexpected `(` after qualified path"));
3516                         }
3517                         // Parse tuple struct or enum pattern
3518                         if self.look_ahead(1, |t| *t == token::DotDot) {
3519                             // This is a "top constructor only" pat
3520                             self.bump();
3521                             self.bump();
3522                             try!(self.expect(&token::CloseDelim(token::Paren)));
3523                             pat = PatEnum(path, None);
3524                         } else {
3525                             let args = try!(self.parse_enum_variant_seq(
3526                                     &token::OpenDelim(token::Paren),
3527                                     &token::CloseDelim(token::Paren),
3528                                     seq_sep_trailing_allowed(token::Comma),
3529                                     |p| p.parse_pat()));
3530                             pat = PatEnum(path, Some(args));
3531                         }
3532                       }
3533                       _ => {
3534                         pat = match qself {
3535                             // Parse qualified path
3536                             Some(qself) => PatQPath(qself, path),
3537                             // Parse nullary enum
3538                             None => PatEnum(path, Some(vec![]))
3539                         };
3540                       }
3541                     }
3542                 }
3543             } else {
3544                 // Try to parse everything else as literal with optional minus
3545                 let begin = try!(self.parse_pat_literal_maybe_minus());
3546                 if self.eat(&token::DotDotDot) {
3547                     let end = try!(self.parse_pat_range_end());
3548                     pat = PatRange(begin, end);
3549                 } else {
3550                     pat = PatLit(begin);
3551                 }
3552             }
3553           }
3554         }
3555
3556         let hi = self.last_span.hi;
3557         Ok(P(ast::Pat {
3558             id: ast::DUMMY_NODE_ID,
3559             node: pat,
3560             span: mk_sp(lo, hi),
3561         }))
3562     }
3563
3564     /// Parse ident or ident @ pat
3565     /// used by the copy foo and ref foo patterns to give a good
3566     /// error message when parsing mistakes like ref foo(a,b)
3567     fn parse_pat_ident(&mut self,
3568                        binding_mode: ast::BindingMode)
3569                        -> PResult<'a, ast::Pat_> {
3570         if !self.token.is_plain_ident() {
3571             let span = self.span;
3572             let tok_str = self.this_token_to_string();
3573             return Err(self.span_fatal(span,
3574                             &format!("expected identifier, found `{}`", tok_str)))
3575         }
3576         let ident = try!(self.parse_ident());
3577         let last_span = self.last_span;
3578         let name = codemap::Spanned{span: last_span, node: ident};
3579         let sub = if self.eat(&token::At) {
3580             Some(try!(self.parse_pat()))
3581         } else {
3582             None
3583         };
3584
3585         // just to be friendly, if they write something like
3586         //   ref Some(i)
3587         // we end up here with ( as the current token.  This shortly
3588         // leads to a parse error.  Note that if there is no explicit
3589         // binding mode then we do not end up here, because the lookahead
3590         // will direct us over to parse_enum_variant()
3591         if self.token == token::OpenDelim(token::Paren) {
3592             let last_span = self.last_span;
3593             return Err(self.span_fatal(
3594                 last_span,
3595                 "expected identifier, found enum pattern"))
3596         }
3597
3598         Ok(PatIdent(binding_mode, name, sub))
3599     }
3600
3601     /// Parse a local variable declaration
3602     fn parse_local(&mut self, attrs: ThinAttributes) -> PResult<'a, P<Local>> {
3603         let lo = self.span.lo;
3604         let pat = try!(self.parse_pat());
3605
3606         let mut ty = None;
3607         if self.eat(&token::Colon) {
3608             ty = Some(try!(self.parse_ty_sum()));
3609         }
3610         let init = try!(self.parse_initializer());
3611         Ok(P(ast::Local {
3612             ty: ty,
3613             pat: pat,
3614             init: init,
3615             id: ast::DUMMY_NODE_ID,
3616             span: mk_sp(lo, self.last_span.hi),
3617             attrs: attrs,
3618         }))
3619     }
3620
3621     /// Parse a "let" stmt
3622     fn parse_let(&mut self, attrs: ThinAttributes) -> PResult<'a, P<Decl>> {
3623         let lo = self.span.lo;
3624         let local = try!(self.parse_local(attrs));
3625         Ok(P(spanned(lo, self.last_span.hi, DeclLocal(local))))
3626     }
3627
3628     /// Parse a structure field
3629     fn parse_name_and_ty(&mut self, pr: Visibility,
3630                          attrs: Vec<Attribute> ) -> PResult<'a, StructField> {
3631         let lo = match pr {
3632             Inherited => self.span.lo,
3633             Public => self.last_span.lo,
3634         };
3635         if !self.token.is_plain_ident() {
3636             return Err(self.fatal("expected ident"));
3637         }
3638         let name = try!(self.parse_ident());
3639         try!(self.expect(&token::Colon));
3640         let ty = try!(self.parse_ty_sum());
3641         Ok(spanned(lo, self.last_span.hi, ast::StructField_ {
3642             kind: NamedField(name, pr),
3643             id: ast::DUMMY_NODE_ID,
3644             ty: ty,
3645             attrs: attrs,
3646         }))
3647     }
3648
3649     /// Emit an expected item after attributes error.
3650     fn expected_item_err(&self, attrs: &[Attribute]) {
3651         let message = match attrs.last() {
3652             Some(&Attribute { node: ast::Attribute_ { is_sugared_doc: true, .. }, .. }) => {
3653                 "expected item after doc comment"
3654             }
3655             _ => "expected item after attributes",
3656         };
3657
3658         self.span_err(self.last_span, message);
3659     }
3660
3661     /// Parse a statement. may include decl.
3662     pub fn parse_stmt(&mut self) -> PResult<'a, Option<P<Stmt>>> {
3663         Ok(try!(self.parse_stmt_()).map(P))
3664     }
3665
3666     fn parse_stmt_(&mut self) -> PResult<'a, Option<Stmt>> {
3667         maybe_whole!(Some deref self, NtStmt);
3668
3669         let attrs = try!(self.parse_outer_attributes());
3670         let lo = self.span.lo;
3671
3672         Ok(Some(if self.check_keyword(keywords::Let) {
3673             try!(self.expect_keyword(keywords::Let));
3674             let decl = try!(self.parse_let(attrs.into_thin_attrs()));
3675             let hi = decl.span.hi;
3676             let stmt = StmtDecl(decl, ast::DUMMY_NODE_ID);
3677             spanned(lo, hi, stmt)
3678         } else if self.token.is_ident()
3679             && !self.token.is_any_keyword()
3680             && self.look_ahead(1, |t| *t == token::Not) {
3681             // it's a macro invocation:
3682
3683             // Potential trouble: if we allow macros with paths instead of
3684             // idents, we'd need to look ahead past the whole path here...
3685             let pth = try!(self.parse_path(NoTypesAllowed));
3686             self.bump();
3687
3688             let id = match self.token {
3689                 token::OpenDelim(_) => token::special_idents::invalid, // no special identifier
3690                 _ => try!(self.parse_ident()),
3691             };
3692
3693             // check that we're pointing at delimiters (need to check
3694             // again after the `if`, because of `parse_ident`
3695             // consuming more tokens).
3696             let delim = match self.token {
3697                 token::OpenDelim(delim) => delim,
3698                 _ => {
3699                     // we only expect an ident if we didn't parse one
3700                     // above.
3701                     let ident_str = if id.name == token::special_idents::invalid.name {
3702                         "identifier, "
3703                     } else {
3704                         ""
3705                     };
3706                     let tok_str = self.this_token_to_string();
3707                     return Err(self.fatal(&format!("expected {}`(` or `{{`, found `{}`",
3708                                        ident_str,
3709                                        tok_str)))
3710                 },
3711             };
3712
3713             let tts = try!(self.parse_unspanned_seq(
3714                 &token::OpenDelim(delim),
3715                 &token::CloseDelim(delim),
3716                 seq_sep_none(),
3717                 |p| p.parse_token_tree()
3718             ));
3719             let hi = self.last_span.hi;
3720
3721             let style = if delim == token::Brace {
3722                 MacStmtWithBraces
3723             } else {
3724                 MacStmtWithoutBraces
3725             };
3726
3727             if id.name == token::special_idents::invalid.name {
3728                 let stmt = StmtMac(P(spanned(lo,
3729                                              hi,
3730                                              Mac_ { path: pth, tts: tts, ctxt: EMPTY_CTXT })),
3731                                    style,
3732                                    attrs.into_thin_attrs());
3733                 spanned(lo, hi, stmt)
3734             } else {
3735                 // if it has a special ident, it's definitely an item
3736                 //
3737                 // Require a semicolon or braces.
3738                 if style != MacStmtWithBraces {
3739                     if !self.eat(&token::Semi) {
3740                         let last_span = self.last_span;
3741                         self.span_err(last_span,
3742                                       "macros that expand to items must \
3743                                        either be surrounded with braces or \
3744                                        followed by a semicolon");
3745                     }
3746                 }
3747                 spanned(lo, hi, StmtDecl(
3748                     P(spanned(lo, hi, DeclItem(
3749                         self.mk_item(
3750                             lo, hi, id /*id is good here*/,
3751                             ItemMac(spanned(lo, hi,
3752                                             Mac_ { path: pth, tts: tts, ctxt: EMPTY_CTXT })),
3753                             Inherited, attrs)))),
3754                     ast::DUMMY_NODE_ID))
3755             }
3756         } else {
3757             // FIXME: Bad copy of attrs
3758             match try!(self.parse_item_(attrs.clone(), false, true)) {
3759                 Some(i) => {
3760                     let hi = i.span.hi;
3761                     let decl = P(spanned(lo, hi, DeclItem(i)));
3762                     spanned(lo, hi, StmtDecl(decl, ast::DUMMY_NODE_ID))
3763                 }
3764                 None => {
3765                     let unused_attrs = |attrs: &[_], s: &mut Self| {
3766                         if attrs.len() > 0 {
3767                             s.span_err(s.span,
3768                                 "expected statement after outer attribute");
3769                         }
3770                     };
3771
3772                     // Do not attempt to parse an expression if we're done here.
3773                     if self.token == token::Semi {
3774                         unused_attrs(&attrs, self);
3775                         self.bump();
3776                         return Ok(None);
3777                     }
3778
3779                     if self.token == token::CloseDelim(token::Brace) {
3780                         unused_attrs(&attrs, self);
3781                         return Ok(None);
3782                     }
3783
3784                     // Remainder are line-expr stmts.
3785                     let e = try!(self.parse_expr_res(
3786                         Restrictions::RESTRICTION_STMT_EXPR, Some(attrs.into_thin_attrs())));
3787                     let hi = e.span.hi;
3788                     let stmt = StmtExpr(e, ast::DUMMY_NODE_ID);
3789                     spanned(lo, hi, stmt)
3790                 }
3791             }
3792         }))
3793     }
3794
3795     /// Is this expression a successfully-parsed statement?
3796     fn expr_is_complete(&mut self, e: &Expr) -> bool {
3797         self.restrictions.contains(Restrictions::RESTRICTION_STMT_EXPR) &&
3798             !classify::expr_requires_semi_to_be_stmt(e)
3799     }
3800
3801     /// Parse a block. No inner attrs are allowed.
3802     pub fn parse_block(&mut self) -> PResult<'a, P<Block>> {
3803         maybe_whole!(no_clone self, NtBlock);
3804
3805         let lo = self.span.lo;
3806
3807         if !self.eat(&token::OpenDelim(token::Brace)) {
3808             let sp = self.span;
3809             let tok = self.this_token_to_string();
3810             return Err(self.span_fatal_help(sp,
3811                                  &format!("expected `{{`, found `{}`", tok),
3812                                  "place this code inside a block"));
3813         }
3814
3815         self.parse_block_tail(lo, DefaultBlock)
3816     }
3817
3818     /// Parse a block. Inner attrs are allowed.
3819     fn parse_inner_attrs_and_block(&mut self) -> PResult<'a, (Vec<Attribute>, P<Block>)> {
3820         maybe_whole!(pair_empty self, NtBlock);
3821
3822         let lo = self.span.lo;
3823         try!(self.expect(&token::OpenDelim(token::Brace)));
3824         Ok((try!(self.parse_inner_attributes()),
3825          try!(self.parse_block_tail(lo, DefaultBlock))))
3826     }
3827
3828     /// Parse the rest of a block expression or function body
3829     /// Precondition: already parsed the '{'.
3830     fn parse_block_tail(&mut self, lo: BytePos, s: BlockCheckMode) -> PResult<'a, P<Block>> {
3831         let mut stmts = vec![];
3832         let mut expr = None;
3833
3834         while !self.eat(&token::CloseDelim(token::Brace)) {
3835             let Spanned {node, span} = if let Some(s) = try!(self.parse_stmt_()) {
3836                 s
3837             } else {
3838                 // Found only `;` or `}`.
3839                 continue;
3840             };
3841             match node {
3842                 StmtExpr(e, _) => {
3843                     try!(self.handle_expression_like_statement(e, span, &mut stmts, &mut expr));
3844                 }
3845                 StmtMac(mac, MacStmtWithoutBraces, attrs) => {
3846                     // statement macro without braces; might be an
3847                     // expr depending on whether a semicolon follows
3848                     match self.token {
3849                         token::Semi => {
3850                             stmts.push(P(Spanned {
3851                                 node: StmtMac(mac, MacStmtWithSemicolon, attrs),
3852                                 span: mk_sp(span.lo, self.span.hi),
3853                             }));
3854                             self.bump();
3855                         }
3856                         _ => {
3857                             let e = self.mk_mac_expr(span.lo, span.hi,
3858                                                      mac.and_then(|m| m.node),
3859                                                      None);
3860                             let lo = e.span.lo;
3861                             let e = try!(self.parse_dot_or_call_expr_with(e, lo, attrs));
3862                             let e = try!(self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e)));
3863                             try!(self.handle_expression_like_statement(
3864                                 e,
3865                                 span,
3866                                 &mut stmts,
3867                                 &mut expr));
3868                         }
3869                     }
3870                 }
3871                 StmtMac(m, style, attrs) => {
3872                     // statement macro; might be an expr
3873                     match self.token {
3874                         token::Semi => {
3875                             stmts.push(P(Spanned {
3876                                 node: StmtMac(m, MacStmtWithSemicolon, attrs),
3877                                 span: mk_sp(span.lo, self.span.hi),
3878                             }));
3879                             self.bump();
3880                         }
3881                         token::CloseDelim(token::Brace) => {
3882                             // if a block ends in `m!(arg)` without
3883                             // a `;`, it must be an expr
3884                             expr = Some(self.mk_mac_expr(span.lo, span.hi,
3885                                                          m.and_then(|x| x.node),
3886                                                          attrs));
3887                         }
3888                         _ => {
3889                             stmts.push(P(Spanned {
3890                                 node: StmtMac(m, style, attrs),
3891                                 span: span
3892                             }));
3893                         }
3894                     }
3895                 }
3896                 _ => { // all other kinds of statements:
3897                     let mut hi = span.hi;
3898                     if classify::stmt_ends_with_semi(&node) {
3899                         try!(self.commit_stmt_expecting(token::Semi));
3900                         hi = self.last_span.hi;
3901                     }
3902
3903                     stmts.push(P(Spanned {
3904                         node: node,
3905                         span: mk_sp(span.lo, hi)
3906                     }));
3907                 }
3908             }
3909         }
3910
3911         Ok(P(ast::Block {
3912             stmts: stmts,
3913             expr: expr,
3914             id: ast::DUMMY_NODE_ID,
3915             rules: s,
3916             span: mk_sp(lo, self.last_span.hi),
3917         }))
3918     }
3919
3920     fn handle_expression_like_statement(
3921             &mut self,
3922             e: P<Expr>,
3923             span: Span,
3924             stmts: &mut Vec<P<Stmt>>,
3925             last_block_expr: &mut Option<P<Expr>>) -> PResult<'a, ()> {
3926         // expression without semicolon
3927         if classify::expr_requires_semi_to_be_stmt(&*e) {
3928             // Just check for errors and recover; do not eat semicolon yet.
3929             try!(self.commit_stmt(&[],
3930                              &[token::Semi, token::CloseDelim(token::Brace)]));
3931         }
3932
3933         match self.token {
3934             token::Semi => {
3935                 self.bump();
3936                 let span_with_semi = Span {
3937                     lo: span.lo,
3938                     hi: self.last_span.hi,
3939                     expn_id: span.expn_id,
3940                 };
3941                 stmts.push(P(Spanned {
3942                     node: StmtSemi(e, ast::DUMMY_NODE_ID),
3943                     span: span_with_semi,
3944                 }));
3945             }
3946             token::CloseDelim(token::Brace) => *last_block_expr = Some(e),
3947             _ => {
3948                 stmts.push(P(Spanned {
3949                     node: StmtExpr(e, ast::DUMMY_NODE_ID),
3950                     span: span
3951                 }));
3952             }
3953         }
3954         Ok(())
3955     }
3956
3957     // Parses a sequence of bounds if a `:` is found,
3958     // otherwise returns empty list.
3959     fn parse_colon_then_ty_param_bounds(&mut self,
3960                                         mode: BoundParsingMode)
3961                                         -> PResult<'a, TyParamBounds>
3962     {
3963         if !self.eat(&token::Colon) {
3964             Ok(P::empty())
3965         } else {
3966             self.parse_ty_param_bounds(mode)
3967         }
3968     }
3969
3970     // matches bounds    = ( boundseq )?
3971     // where   boundseq  = ( polybound + boundseq ) | polybound
3972     // and     polybound = ( 'for' '<' 'region '>' )? bound
3973     // and     bound     = 'region | trait_ref
3974     fn parse_ty_param_bounds(&mut self,
3975                              mode: BoundParsingMode)
3976                              -> PResult<'a, TyParamBounds>
3977     {
3978         let mut result = vec!();
3979         loop {
3980             let question_span = self.span;
3981             let ate_question = self.eat(&token::Question);
3982             match self.token {
3983                 token::Lifetime(lifetime) => {
3984                     if ate_question {
3985                         self.span_err(question_span,
3986                                       "`?` may only modify trait bounds, not lifetime bounds");
3987                     }
3988                     result.push(RegionTyParamBound(ast::Lifetime {
3989                         id: ast::DUMMY_NODE_ID,
3990                         span: self.span,
3991                         name: lifetime.name
3992                     }));
3993                     self.bump();
3994                 }
3995                 token::ModSep | token::Ident(..) => {
3996                     let poly_trait_ref = try!(self.parse_poly_trait_ref());
3997                     let modifier = if ate_question {
3998                         if mode == BoundParsingMode::Modified {
3999                             TraitBoundModifier::Maybe
4000                         } else {
4001                             self.span_err(question_span,
4002                                           "unexpected `?`");
4003                             TraitBoundModifier::None
4004                         }
4005                     } else {
4006                         TraitBoundModifier::None
4007                     };
4008                     result.push(TraitTyParamBound(poly_trait_ref, modifier))
4009                 }
4010                 _ => break,
4011             }
4012
4013             if !self.eat(&token::BinOp(token::Plus)) {
4014                 break;
4015             }
4016         }
4017
4018         return Ok(P::from_vec(result));
4019     }
4020
4021     /// Matches typaram = IDENT (`?` unbound)? optbounds ( EQ ty )?
4022     fn parse_ty_param(&mut self) -> PResult<'a, TyParam> {
4023         let span = self.span;
4024         let ident = try!(self.parse_ident());
4025
4026         let bounds = try!(self.parse_colon_then_ty_param_bounds(BoundParsingMode::Modified));
4027
4028         let default = if self.check(&token::Eq) {
4029             self.bump();
4030             Some(try!(self.parse_ty_sum()))
4031         } else {
4032             None
4033         };
4034
4035         Ok(TyParam {
4036             ident: ident,
4037             id: ast::DUMMY_NODE_ID,
4038             bounds: bounds,
4039             default: default,
4040             span: span,
4041         })
4042     }
4043
4044     /// Parse a set of optional generic type parameter declarations. Where
4045     /// clauses are not parsed here, and must be added later via
4046     /// `parse_where_clause()`.
4047     ///
4048     /// matches generics = ( ) | ( < > ) | ( < typaramseq ( , )? > ) | ( < lifetimes ( , )? > )
4049     ///                  | ( < lifetimes , typaramseq ( , )? > )
4050     /// where   typaramseq = ( typaram ) | ( typaram , typaramseq )
4051     pub fn parse_generics(&mut self) -> PResult<'a, ast::Generics> {
4052         maybe_whole!(self, NtGenerics);
4053
4054         if self.eat(&token::Lt) {
4055             let lifetime_defs = try!(self.parse_lifetime_defs());
4056             let mut seen_default = false;
4057             let ty_params = try!(self.parse_seq_to_gt(Some(token::Comma), |p| {
4058                 try!(p.forbid_lifetime());
4059                 let ty_param = try!(p.parse_ty_param());
4060                 if ty_param.default.is_some() {
4061                     seen_default = true;
4062                 } else if seen_default {
4063                     let last_span = p.last_span;
4064                     p.span_err(last_span,
4065                                "type parameters with a default must be trailing");
4066                 }
4067                 Ok(ty_param)
4068             }));
4069             Ok(ast::Generics {
4070                 lifetimes: lifetime_defs,
4071                 ty_params: ty_params,
4072                 where_clause: WhereClause {
4073                     id: ast::DUMMY_NODE_ID,
4074                     predicates: Vec::new(),
4075                 }
4076             })
4077         } else {
4078             Ok(ast::Generics::default())
4079         }
4080     }
4081
4082     fn parse_generic_values_after_lt(&mut self) -> PResult<'a, (Vec<ast::Lifetime>,
4083                                                             Vec<P<Ty>>,
4084                                                             Vec<P<TypeBinding>>)> {
4085         let span_lo = self.span.lo;
4086         let lifetimes = try!(self.parse_lifetimes(token::Comma));
4087
4088         let missing_comma = !lifetimes.is_empty() &&
4089                             !self.token.is_like_gt() &&
4090                             self.last_token
4091                                 .as_ref().map_or(true,
4092                                                  |x| &**x != &token::Comma);
4093
4094         if missing_comma {
4095
4096             let msg = format!("expected `,` or `>` after lifetime \
4097                               name, found `{}`",
4098                               self.this_token_to_string());
4099             let mut err = self.diagnostic().struct_span_err(self.span, &msg);
4100
4101             let span_hi = self.span.hi;
4102             let span_hi = match self.parse_ty() {
4103                 Ok(..) => self.span.hi,
4104                 Err(ref mut err) => {
4105                     err.cancel();
4106                     span_hi
4107                 }
4108             };
4109
4110             let msg = format!("did you mean a single argument type &'a Type, \
4111                               or did you mean the comma-separated arguments \
4112                               'a, Type?");
4113             err.span_note(mk_sp(span_lo, span_hi), &msg);
4114             err.emit();
4115
4116             self.abort_if_errors()
4117         }
4118
4119         // First parse types.
4120         let (types, returned) = try!(self.parse_seq_to_gt_or_return(
4121             Some(token::Comma),
4122             |p| {
4123                 try!(p.forbid_lifetime());
4124                 if p.look_ahead(1, |t| t == &token::Eq) {
4125                     Ok(None)
4126                 } else {
4127                     Ok(Some(try!(p.parse_ty_sum())))
4128                 }
4129             }
4130         ));
4131
4132         // If we found the `>`, don't continue.
4133         if !returned {
4134             return Ok((lifetimes, types.into_vec(), Vec::new()));
4135         }
4136
4137         // Then parse type bindings.
4138         let bindings = try!(self.parse_seq_to_gt(
4139             Some(token::Comma),
4140             |p| {
4141                 try!(p.forbid_lifetime());
4142                 let lo = p.span.lo;
4143                 let ident = try!(p.parse_ident());
4144                 let found_eq = p.eat(&token::Eq);
4145                 if !found_eq {
4146                     let span = p.span;
4147                     p.span_warn(span, "whoops, no =?");
4148                 }
4149                 let ty = try!(p.parse_ty());
4150                 let hi = ty.span.hi;
4151                 let span = mk_sp(lo, hi);
4152                 return Ok(P(TypeBinding{id: ast::DUMMY_NODE_ID,
4153                     ident: ident,
4154                     ty: ty,
4155                     span: span,
4156                 }));
4157             }
4158         ));
4159         Ok((lifetimes, types.into_vec(), bindings.into_vec()))
4160     }
4161
4162     fn forbid_lifetime(&mut self) -> PResult<'a, ()> {
4163         if self.token.is_lifetime() {
4164             let span = self.span;
4165             return Err(self.span_fatal(span, "lifetime parameters must be declared \
4166                                         prior to type parameters"))
4167         }
4168         Ok(())
4169     }
4170
4171     /// Parses an optional `where` clause and places it in `generics`.
4172     ///
4173     /// ```ignore
4174     /// where T : Trait<U, V> + 'b, 'a : 'b
4175     /// ```
4176     pub fn parse_where_clause(&mut self) -> PResult<'a, ast::WhereClause> {
4177         maybe_whole!(self, NtWhereClause);
4178
4179         let mut where_clause = WhereClause {
4180             id: ast::DUMMY_NODE_ID,
4181             predicates: Vec::new(),
4182         };
4183
4184         if !self.eat_keyword(keywords::Where) {
4185             return Ok(where_clause);
4186         }
4187
4188         let mut parsed_something = false;
4189         loop {
4190             let lo = self.span.lo;
4191             match self.token {
4192                 token::OpenDelim(token::Brace) => {
4193                     break
4194                 }
4195
4196                 token::Lifetime(..) => {
4197                     let bounded_lifetime =
4198                         try!(self.parse_lifetime());
4199
4200                     self.eat(&token::Colon);
4201
4202                     let bounds =
4203                         try!(self.parse_lifetimes(token::BinOp(token::Plus)));
4204
4205                     let hi = self.last_span.hi;
4206                     let span = mk_sp(lo, hi);
4207
4208                     where_clause.predicates.push(ast::WherePredicate::RegionPredicate(
4209                         ast::WhereRegionPredicate {
4210                             span: span,
4211                             lifetime: bounded_lifetime,
4212                             bounds: bounds
4213                         }
4214                     ));
4215
4216                     parsed_something = true;
4217                 }
4218
4219                 _ => {
4220                     let bound_lifetimes = if self.eat_keyword(keywords::For) {
4221                         // Higher ranked constraint.
4222                         try!(self.expect(&token::Lt));
4223                         let lifetime_defs = try!(self.parse_lifetime_defs());
4224                         try!(self.expect_gt());
4225                         lifetime_defs
4226                     } else {
4227                         vec![]
4228                     };
4229
4230                     let bounded_ty = try!(self.parse_ty());
4231
4232                     if self.eat(&token::Colon) {
4233                         let bounds = try!(self.parse_ty_param_bounds(BoundParsingMode::Bare));
4234                         let hi = self.last_span.hi;
4235                         let span = mk_sp(lo, hi);
4236
4237                         if bounds.is_empty() {
4238                             self.span_err(span,
4239                                           "each predicate in a `where` clause must have \
4240                                            at least one bound in it");
4241                         }
4242
4243                         where_clause.predicates.push(ast::WherePredicate::BoundPredicate(
4244                                 ast::WhereBoundPredicate {
4245                                     span: span,
4246                                     bound_lifetimes: bound_lifetimes,
4247                                     bounded_ty: bounded_ty,
4248                                     bounds: bounds,
4249                         }));
4250
4251                         parsed_something = true;
4252                     } else if self.eat(&token::Eq) {
4253                         // let ty = try!(self.parse_ty());
4254                         let hi = self.last_span.hi;
4255                         let span = mk_sp(lo, hi);
4256                         // where_clause.predicates.push(
4257                         //     ast::WherePredicate::EqPredicate(ast::WhereEqPredicate {
4258                         //         id: ast::DUMMY_NODE_ID,
4259                         //         span: span,
4260                         //         path: panic!("NYI"), //bounded_ty,
4261                         //         ty: ty,
4262                         // }));
4263                         // parsed_something = true;
4264                         // // FIXME(#18433)
4265                         self.span_err(span,
4266                                      "equality constraints are not yet supported \
4267                                      in where clauses (#20041)");
4268                     } else {
4269                         let last_span = self.last_span;
4270                         self.span_err(last_span,
4271                               "unexpected token in `where` clause");
4272                     }
4273                 }
4274             };
4275
4276             if !self.eat(&token::Comma) {
4277                 break
4278             }
4279         }
4280
4281         if !parsed_something {
4282             let last_span = self.last_span;
4283             self.span_err(last_span,
4284                           "a `where` clause must have at least one predicate \
4285                            in it");
4286         }
4287
4288         Ok(where_clause)
4289     }
4290
4291     fn parse_fn_args(&mut self, named_args: bool, allow_variadic: bool)
4292                      -> PResult<'a, (Vec<Arg> , bool)> {
4293         let sp = self.span;
4294         let mut args: Vec<Option<Arg>> =
4295             try!(self.parse_unspanned_seq(
4296                 &token::OpenDelim(token::Paren),
4297                 &token::CloseDelim(token::Paren),
4298                 seq_sep_trailing_allowed(token::Comma),
4299                 |p| {
4300                     if p.token == token::DotDotDot {
4301                         p.bump();
4302                         if allow_variadic {
4303                             if p.token != token::CloseDelim(token::Paren) {
4304                                 let span = p.span;
4305                                 return Err(p.span_fatal(span,
4306                                     "`...` must be last in argument list for variadic function"))
4307                             }
4308                         } else {
4309                             let span = p.span;
4310                             return Err(p.span_fatal(span,
4311                                          "only foreign functions are allowed to be variadic"))
4312                         }
4313                         Ok(None)
4314                     } else {
4315                         Ok(Some(try!(p.parse_arg_general(named_args))))
4316                     }
4317                 }
4318             ));
4319
4320         let variadic = match args.pop() {
4321             Some(None) => true,
4322             Some(x) => {
4323                 // Need to put back that last arg
4324                 args.push(x);
4325                 false
4326             }
4327             None => false
4328         };
4329
4330         if variadic && args.is_empty() {
4331             self.span_err(sp,
4332                           "variadic function must be declared with at least one named argument");
4333         }
4334
4335         let args = args.into_iter().map(|x| x.unwrap()).collect();
4336
4337         Ok((args, variadic))
4338     }
4339
4340     /// Parse the argument list and result type of a function declaration
4341     pub fn parse_fn_decl(&mut self, allow_variadic: bool) -> PResult<'a, P<FnDecl>> {
4342
4343         let (args, variadic) = try!(self.parse_fn_args(true, allow_variadic));
4344         let ret_ty = try!(self.parse_ret_ty());
4345
4346         Ok(P(FnDecl {
4347             inputs: args,
4348             output: ret_ty,
4349             variadic: variadic
4350         }))
4351     }
4352
4353     fn is_self_ident(&mut self) -> bool {
4354         match self.token {
4355           token::Ident(id, token::Plain) => id.name == special_idents::self_.name,
4356           _ => false
4357         }
4358     }
4359
4360     fn expect_self_ident(&mut self) -> PResult<'a, ast::Ident> {
4361         match self.token {
4362             token::Ident(id, token::Plain) if id.name == special_idents::self_.name => {
4363                 self.bump();
4364                 Ok(id)
4365             },
4366             _ => {
4367                 let token_str = self.this_token_to_string();
4368                 return Err(self.fatal(&format!("expected `self`, found `{}`",
4369                                    token_str)))
4370             }
4371         }
4372     }
4373
4374     fn is_self_type_ident(&mut self) -> bool {
4375         match self.token {
4376           token::Ident(id, token::Plain) => id.name == special_idents::type_self.name,
4377           _ => false
4378         }
4379     }
4380
4381     fn expect_self_type_ident(&mut self) -> PResult<'a, ast::Ident> {
4382         match self.token {
4383             token::Ident(id, token::Plain) if id.name == special_idents::type_self.name => {
4384                 self.bump();
4385                 Ok(id)
4386             },
4387             _ => {
4388                 let token_str = self.this_token_to_string();
4389                 Err(self.fatal(&format!("expected `Self`, found `{}`",
4390                                    token_str)))
4391             }
4392         }
4393     }
4394
4395     /// Parse the argument list and result type of a function
4396     /// that may have a self type.
4397     fn parse_fn_decl_with_self<F>(&mut self,
4398                                   parse_arg_fn: F) -> PResult<'a, (ExplicitSelf, P<FnDecl>)> where
4399         F: FnMut(&mut Parser<'a>) -> PResult<'a,  Arg>,
4400     {
4401         fn maybe_parse_borrowed_explicit_self<'b>(this: &mut Parser<'b>)
4402                                                   -> PResult<'b,  ast::ExplicitSelf_> {
4403             // The following things are possible to see here:
4404             //
4405             //     fn(&mut self)
4406             //     fn(&mut self)
4407             //     fn(&'lt self)
4408             //     fn(&'lt mut self)
4409             //
4410             // We already know that the current token is `&`.
4411
4412             if this.look_ahead(1, |t| t.is_keyword(keywords::SelfValue)) {
4413                 this.bump();
4414                 Ok(SelfRegion(None, MutImmutable, try!(this.expect_self_ident())))
4415             } else if this.look_ahead(1, |t| t.is_mutability()) &&
4416                       this.look_ahead(2, |t| t.is_keyword(keywords::SelfValue)) {
4417                 this.bump();
4418                 let mutability = try!(this.parse_mutability());
4419                 Ok(SelfRegion(None, mutability, try!(this.expect_self_ident())))
4420             } else if this.look_ahead(1, |t| t.is_lifetime()) &&
4421                       this.look_ahead(2, |t| t.is_keyword(keywords::SelfValue)) {
4422                 this.bump();
4423                 let lifetime = try!(this.parse_lifetime());
4424                 Ok(SelfRegion(Some(lifetime), MutImmutable, try!(this.expect_self_ident())))
4425             } else if this.look_ahead(1, |t| t.is_lifetime()) &&
4426                       this.look_ahead(2, |t| t.is_mutability()) &&
4427                       this.look_ahead(3, |t| t.is_keyword(keywords::SelfValue)) {
4428                 this.bump();
4429                 let lifetime = try!(this.parse_lifetime());
4430                 let mutability = try!(this.parse_mutability());
4431                 Ok(SelfRegion(Some(lifetime), mutability, try!(this.expect_self_ident())))
4432             } else {
4433                 Ok(SelfStatic)
4434             }
4435         }
4436
4437         try!(self.expect(&token::OpenDelim(token::Paren)));
4438
4439         // A bit of complexity and lookahead is needed here in order to be
4440         // backwards compatible.
4441         let lo = self.span.lo;
4442         let mut self_ident_lo = self.span.lo;
4443         let mut self_ident_hi = self.span.hi;
4444
4445         let mut mutbl_self = MutImmutable;
4446         let explicit_self = match self.token {
4447             token::BinOp(token::And) => {
4448                 let eself = try!(maybe_parse_borrowed_explicit_self(self));
4449                 self_ident_lo = self.last_span.lo;
4450                 self_ident_hi = self.last_span.hi;
4451                 eself
4452             }
4453             token::BinOp(token::Star) => {
4454                 // Possibly "*self" or "*mut self" -- not supported. Try to avoid
4455                 // emitting cryptic "unexpected token" errors.
4456                 self.bump();
4457                 let _mutability = if self.token.is_mutability() {
4458                     try!(self.parse_mutability())
4459                 } else {
4460                     MutImmutable
4461                 };
4462                 if self.is_self_ident() {
4463                     let span = self.span;
4464                     self.span_err(span, "cannot pass self by raw pointer");
4465                     self.bump();
4466                 }
4467                 // error case, making bogus self ident:
4468                 SelfValue(special_idents::self_)
4469             }
4470             token::Ident(..) => {
4471                 if self.is_self_ident() {
4472                     let self_ident = try!(self.expect_self_ident());
4473
4474                     // Determine whether this is the fully explicit form, `self:
4475                     // TYPE`.
4476                     if self.eat(&token::Colon) {
4477                         SelfExplicit(try!(self.parse_ty_sum()), self_ident)
4478                     } else {
4479                         SelfValue(self_ident)
4480                     }
4481                 } else if self.token.is_mutability() &&
4482                         self.look_ahead(1, |t| t.is_keyword(keywords::SelfValue)) {
4483                     mutbl_self = try!(self.parse_mutability());
4484                     let self_ident = try!(self.expect_self_ident());
4485
4486                     // Determine whether this is the fully explicit form,
4487                     // `self: TYPE`.
4488                     if self.eat(&token::Colon) {
4489                         SelfExplicit(try!(self.parse_ty_sum()), self_ident)
4490                     } else {
4491                         SelfValue(self_ident)
4492                     }
4493                 } else {
4494                     SelfStatic
4495                 }
4496             }
4497             _ => SelfStatic,
4498         };
4499
4500         let explicit_self_sp = mk_sp(self_ident_lo, self_ident_hi);
4501
4502         // shared fall-through for the three cases below. borrowing prevents simply
4503         // writing this as a closure
4504         macro_rules! parse_remaining_arguments {
4505             ($self_id:ident) =>
4506             {
4507             // If we parsed a self type, expect a comma before the argument list.
4508             match self.token {
4509                 token::Comma => {
4510                     self.bump();
4511                     let sep = seq_sep_trailing_allowed(token::Comma);
4512                     let mut fn_inputs = try!(self.parse_seq_to_before_end(
4513                         &token::CloseDelim(token::Paren),
4514                         sep,
4515                         parse_arg_fn
4516                     ));
4517                     fn_inputs.insert(0, Arg::new_self(explicit_self_sp, mutbl_self, $self_id));
4518                     fn_inputs
4519                 }
4520                 token::CloseDelim(token::Paren) => {
4521                     vec!(Arg::new_self(explicit_self_sp, mutbl_self, $self_id))
4522                 }
4523                 _ => {
4524                     let token_str = self.this_token_to_string();
4525                     return Err(self.fatal(&format!("expected `,` or `)`, found `{}`",
4526                                        token_str)))
4527                 }
4528             }
4529             }
4530         }
4531
4532         let fn_inputs = match explicit_self {
4533             SelfStatic =>  {
4534                 let sep = seq_sep_trailing_allowed(token::Comma);
4535                 try!(self.parse_seq_to_before_end(&token::CloseDelim(token::Paren),
4536                                                   sep, parse_arg_fn))
4537             }
4538             SelfValue(id) => parse_remaining_arguments!(id),
4539             SelfRegion(_,_,id) => parse_remaining_arguments!(id),
4540             SelfExplicit(_,id) => parse_remaining_arguments!(id),
4541         };
4542
4543
4544         try!(self.expect(&token::CloseDelim(token::Paren)));
4545
4546         let hi = self.span.hi;
4547
4548         let ret_ty = try!(self.parse_ret_ty());
4549
4550         let fn_decl = P(FnDecl {
4551             inputs: fn_inputs,
4552             output: ret_ty,
4553             variadic: false
4554         });
4555
4556         Ok((spanned(lo, hi, explicit_self), fn_decl))
4557     }
4558
4559     // parse the |arg, arg| header on a lambda
4560     fn parse_fn_block_decl(&mut self) -> PResult<'a, P<FnDecl>> {
4561         let inputs_captures = {
4562             if self.eat(&token::OrOr) {
4563                 Vec::new()
4564             } else {
4565                 try!(self.expect(&token::BinOp(token::Or)));
4566                 try!(self.parse_obsolete_closure_kind());
4567                 let args = try!(self.parse_seq_to_before_end(
4568                     &token::BinOp(token::Or),
4569                     seq_sep_trailing_allowed(token::Comma),
4570                     |p| p.parse_fn_block_arg()
4571                 ));
4572                 self.bump();
4573                 args
4574             }
4575         };
4576         let output = try!(self.parse_ret_ty());
4577
4578         Ok(P(FnDecl {
4579             inputs: inputs_captures,
4580             output: output,
4581             variadic: false
4582         }))
4583     }
4584
4585     /// Parse the name and optional generic types of a function header.
4586     fn parse_fn_header(&mut self) -> PResult<'a, (Ident, ast::Generics)> {
4587         let id = try!(self.parse_ident());
4588         let generics = try!(self.parse_generics());
4589         Ok((id, generics))
4590     }
4591
4592     fn mk_item(&mut self, lo: BytePos, hi: BytePos, ident: Ident,
4593                node: Item_, vis: Visibility,
4594                attrs: Vec<Attribute>) -> P<Item> {
4595         P(Item {
4596             ident: ident,
4597             attrs: attrs,
4598             id: ast::DUMMY_NODE_ID,
4599             node: node,
4600             vis: vis,
4601             span: mk_sp(lo, hi)
4602         })
4603     }
4604
4605     /// Parse an item-position function declaration.
4606     fn parse_item_fn(&mut self,
4607                      unsafety: Unsafety,
4608                      constness: Constness,
4609                      abi: abi::Abi)
4610                      -> PResult<'a, ItemInfo> {
4611         let (ident, mut generics) = try!(self.parse_fn_header());
4612         let decl = try!(self.parse_fn_decl(false));
4613         generics.where_clause = try!(self.parse_where_clause());
4614         let (inner_attrs, body) = try!(self.parse_inner_attrs_and_block());
4615         Ok((ident, ItemFn(decl, unsafety, constness, abi, generics, body), Some(inner_attrs)))
4616     }
4617
4618     /// true if we are looking at `const ID`, false for things like `const fn` etc
4619     pub fn is_const_item(&mut self) -> bool {
4620         self.token.is_keyword(keywords::Const) &&
4621             !self.look_ahead(1, |t| t.is_keyword(keywords::Fn)) &&
4622             !self.look_ahead(1, |t| t.is_keyword(keywords::Unsafe))
4623     }
4624
4625     /// parses all the "front matter" for a `fn` declaration, up to
4626     /// and including the `fn` keyword:
4627     ///
4628     /// - `const fn`
4629     /// - `unsafe fn`
4630     /// - `const unsafe fn`
4631     /// - `extern fn`
4632     /// - etc
4633     pub fn parse_fn_front_matter(&mut self)
4634                                  -> PResult<'a, (ast::Constness, ast::Unsafety, abi::Abi)> {
4635         let is_const_fn = self.eat_keyword(keywords::Const);
4636         let unsafety = try!(self.parse_unsafety());
4637         let (constness, unsafety, abi) = if is_const_fn {
4638             (Constness::Const, unsafety, abi::Rust)
4639         } else {
4640             let abi = if self.eat_keyword(keywords::Extern) {
4641                 try!(self.parse_opt_abi()).unwrap_or(abi::C)
4642             } else {
4643                 abi::Rust
4644             };
4645             (Constness::NotConst, unsafety, abi)
4646         };
4647         try!(self.expect_keyword(keywords::Fn));
4648         Ok((constness, unsafety, abi))
4649     }
4650
4651     /// Parse an impl item.
4652     pub fn parse_impl_item(&mut self) -> PResult<'a, P<ImplItem>> {
4653         maybe_whole!(no_clone self, NtImplItem);
4654
4655         let mut attrs = try!(self.parse_outer_attributes());
4656         let lo = self.span.lo;
4657         let vis = try!(self.parse_visibility());
4658         let (name, node) = if self.eat_keyword(keywords::Type) {
4659             let name = try!(self.parse_ident());
4660             try!(self.expect(&token::Eq));
4661             let typ = try!(self.parse_ty_sum());
4662             try!(self.expect(&token::Semi));
4663             (name, ast::ImplItemKind::Type(typ))
4664         } else if self.is_const_item() {
4665             try!(self.expect_keyword(keywords::Const));
4666             let name = try!(self.parse_ident());
4667             try!(self.expect(&token::Colon));
4668             let typ = try!(self.parse_ty_sum());
4669             try!(self.expect(&token::Eq));
4670             let expr = try!(self.parse_expr());
4671             try!(self.commit_expr_expecting(&expr, token::Semi));
4672             (name, ast::ImplItemKind::Const(typ, expr))
4673         } else {
4674             let (name, inner_attrs, node) = try!(self.parse_impl_method(vis));
4675             attrs.extend(inner_attrs);
4676             (name, node)
4677         };
4678
4679         Ok(P(ImplItem {
4680             id: ast::DUMMY_NODE_ID,
4681             span: mk_sp(lo, self.last_span.hi),
4682             ident: name,
4683             vis: vis,
4684             attrs: attrs,
4685             node: node
4686         }))
4687     }
4688
4689     fn complain_if_pub_macro(&mut self, visa: Visibility, span: Span) {
4690         match visa {
4691             Public => {
4692                 let is_macro_rules: bool = match self.token {
4693                     token::Ident(sid, _) => sid.name == intern("macro_rules"),
4694                     _ => false,
4695                 };
4696                 if is_macro_rules {
4697                     self.diagnostic().struct_span_err(span, "can't qualify macro_rules \
4698                                                              invocation with `pub`")
4699                                      .fileline_help(span, "did you mean #[macro_export]?")
4700                                      .emit();
4701                 } else {
4702                     self.diagnostic().struct_span_err(span, "can't qualify macro \
4703                                                              invocation with `pub`")
4704                                      .fileline_help(span, "try adjusting the macro to put `pub` \
4705                                                            inside the invocation")
4706                                      .emit();
4707                 }
4708             }
4709             Inherited => (),
4710         }
4711     }
4712
4713     /// Parse a method or a macro invocation in a trait impl.
4714     fn parse_impl_method(&mut self, vis: Visibility)
4715                          -> PResult<'a, (Ident, Vec<ast::Attribute>, ast::ImplItemKind)> {
4716         // code copied from parse_macro_use_or_failure... abstraction!
4717         if !self.token.is_any_keyword()
4718             && self.look_ahead(1, |t| *t == token::Not)
4719             && (self.look_ahead(2, |t| *t == token::OpenDelim(token::Paren))
4720                 || self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))) {
4721             // method macro.
4722
4723             let last_span = self.last_span;
4724             self.complain_if_pub_macro(vis, last_span);
4725
4726             let lo = self.span.lo;
4727             let pth = try!(self.parse_path(NoTypesAllowed));
4728             try!(self.expect(&token::Not));
4729
4730             // eat a matched-delimiter token tree:
4731             let delim = try!(self.expect_open_delim());
4732             let tts = try!(self.parse_seq_to_end(&token::CloseDelim(delim),
4733                                             seq_sep_none(),
4734                                             |p| p.parse_token_tree()));
4735             let m_ = Mac_ { path: pth, tts: tts, ctxt: EMPTY_CTXT };
4736             let m: ast::Mac = codemap::Spanned { node: m_,
4737                                                 span: mk_sp(lo,
4738                                                             self.last_span.hi) };
4739             if delim != token::Brace {
4740                 try!(self.expect(&token::Semi))
4741             }
4742             Ok((token::special_idents::invalid, vec![], ast::ImplItemKind::Macro(m)))
4743         } else {
4744             let (constness, unsafety, abi) = try!(self.parse_fn_front_matter());
4745             let ident = try!(self.parse_ident());
4746             let mut generics = try!(self.parse_generics());
4747             let (explicit_self, decl) = try!(self.parse_fn_decl_with_self(|p| {
4748                     p.parse_arg()
4749                 }));
4750             generics.where_clause = try!(self.parse_where_clause());
4751             let (inner_attrs, body) = try!(self.parse_inner_attrs_and_block());
4752             Ok((ident, inner_attrs, ast::ImplItemKind::Method(ast::MethodSig {
4753                 generics: generics,
4754                 abi: abi,
4755                 explicit_self: explicit_self,
4756                 unsafety: unsafety,
4757                 constness: constness,
4758                 decl: decl
4759              }, body)))
4760         }
4761     }
4762
4763     /// Parse trait Foo { ... }
4764     fn parse_item_trait(&mut self, unsafety: Unsafety) -> PResult<'a, ItemInfo> {
4765
4766         let ident = try!(self.parse_ident());
4767         let mut tps = try!(self.parse_generics());
4768
4769         // Parse supertrait bounds.
4770         let bounds = try!(self.parse_colon_then_ty_param_bounds(BoundParsingMode::Bare));
4771
4772         tps.where_clause = try!(self.parse_where_clause());
4773
4774         let meths = try!(self.parse_trait_items());
4775         Ok((ident, ItemTrait(unsafety, tps, bounds, meths), None))
4776     }
4777
4778     /// Parses items implementations variants
4779     ///    impl<T> Foo { ... }
4780     ///    impl<T> ToString for &'static T { ... }
4781     ///    impl Send for .. {}
4782     fn parse_item_impl(&mut self, unsafety: ast::Unsafety) -> PResult<'a, ItemInfo> {
4783         let impl_span = self.span;
4784
4785         // First, parse type parameters if necessary.
4786         let mut generics = try!(self.parse_generics());
4787
4788         // Special case: if the next identifier that follows is '(', don't
4789         // allow this to be parsed as a trait.
4790         let could_be_trait = self.token != token::OpenDelim(token::Paren);
4791
4792         let neg_span = self.span;
4793         let polarity = if self.eat(&token::Not) {
4794             ast::ImplPolarity::Negative
4795         } else {
4796             ast::ImplPolarity::Positive
4797         };
4798
4799         // Parse the trait.
4800         let mut ty = try!(self.parse_ty_sum());
4801
4802         // Parse traits, if necessary.
4803         let opt_trait = if could_be_trait && self.eat_keyword(keywords::For) {
4804             // New-style trait. Reinterpret the type as a trait.
4805             match ty.node {
4806                 TyPath(None, ref path) => {
4807                     Some(TraitRef {
4808                         path: (*path).clone(),
4809                         ref_id: ty.id,
4810                     })
4811                 }
4812                 _ => {
4813                     self.span_err(ty.span, "not a trait");
4814                     None
4815                 }
4816             }
4817         } else {
4818             match polarity {
4819                 ast::ImplPolarity::Negative => {
4820                     // This is a negated type implementation
4821                     // `impl !MyType {}`, which is not allowed.
4822                     self.span_err(neg_span, "inherent implementation can't be negated");
4823                 },
4824                 _ => {}
4825             }
4826             None
4827         };
4828
4829         if opt_trait.is_some() && self.eat(&token::DotDot) {
4830             if generics.is_parameterized() {
4831                 self.span_err(impl_span, "default trait implementations are not \
4832                                           allowed to have generics");
4833             }
4834
4835             try!(self.expect(&token::OpenDelim(token::Brace)));
4836             try!(self.expect(&token::CloseDelim(token::Brace)));
4837             Ok((ast_util::impl_pretty_name(&opt_trait, None),
4838              ItemDefaultImpl(unsafety, opt_trait.unwrap()), None))
4839         } else {
4840             if opt_trait.is_some() {
4841                 ty = try!(self.parse_ty_sum());
4842             }
4843             generics.where_clause = try!(self.parse_where_clause());
4844
4845             try!(self.expect(&token::OpenDelim(token::Brace)));
4846             let attrs = try!(self.parse_inner_attributes());
4847
4848             let mut impl_items = vec![];
4849             while !self.eat(&token::CloseDelim(token::Brace)) {
4850                 impl_items.push(try!(self.parse_impl_item()));
4851             }
4852
4853             Ok((ast_util::impl_pretty_name(&opt_trait, Some(&*ty)),
4854              ItemImpl(unsafety, polarity, generics, opt_trait, ty, impl_items),
4855              Some(attrs)))
4856         }
4857     }
4858
4859     /// Parse a::B<String,i32>
4860     fn parse_trait_ref(&mut self) -> PResult<'a, TraitRef> {
4861         Ok(ast::TraitRef {
4862             path: try!(self.parse_path(LifetimeAndTypesWithoutColons)),
4863             ref_id: ast::DUMMY_NODE_ID,
4864         })
4865     }
4866
4867     fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<ast::LifetimeDef>> {
4868         if self.eat_keyword(keywords::For) {
4869             try!(self.expect(&token::Lt));
4870             let lifetime_defs = try!(self.parse_lifetime_defs());
4871             try!(self.expect_gt());
4872             Ok(lifetime_defs)
4873         } else {
4874             Ok(Vec::new())
4875         }
4876     }
4877
4878     /// Parse for<'l> a::B<String,i32>
4879     fn parse_poly_trait_ref(&mut self) -> PResult<'a, PolyTraitRef> {
4880         let lo = self.span.lo;
4881         let lifetime_defs = try!(self.parse_late_bound_lifetime_defs());
4882
4883         Ok(ast::PolyTraitRef {
4884             bound_lifetimes: lifetime_defs,
4885             trait_ref: try!(self.parse_trait_ref()),
4886             span: mk_sp(lo, self.last_span.hi),
4887         })
4888     }
4889
4890     /// Parse struct Foo { ... }
4891     fn parse_item_struct(&mut self) -> PResult<'a, ItemInfo> {
4892         let class_name = try!(self.parse_ident());
4893         let mut generics = try!(self.parse_generics());
4894
4895         // There is a special case worth noting here, as reported in issue #17904.
4896         // If we are parsing a tuple struct it is the case that the where clause
4897         // should follow the field list. Like so:
4898         //
4899         // struct Foo<T>(T) where T: Copy;
4900         //
4901         // If we are parsing a normal record-style struct it is the case
4902         // that the where clause comes before the body, and after the generics.
4903         // So if we look ahead and see a brace or a where-clause we begin
4904         // parsing a record style struct.
4905         //
4906         // Otherwise if we look ahead and see a paren we parse a tuple-style
4907         // struct.
4908
4909         let vdata = if self.token.is_keyword(keywords::Where) {
4910             generics.where_clause = try!(self.parse_where_clause());
4911             if self.eat(&token::Semi) {
4912                 // If we see a: `struct Foo<T> where T: Copy;` style decl.
4913                 VariantData::Unit(ast::DUMMY_NODE_ID)
4914             } else {
4915                 // If we see: `struct Foo<T> where T: Copy { ... }`
4916                 VariantData::Struct(try!(self.parse_record_struct_body(ParsePub::Yes)),
4917                                     ast::DUMMY_NODE_ID)
4918             }
4919         // No `where` so: `struct Foo<T>;`
4920         } else if self.eat(&token::Semi) {
4921             VariantData::Unit(ast::DUMMY_NODE_ID)
4922         // Record-style struct definition
4923         } else if self.token == token::OpenDelim(token::Brace) {
4924             VariantData::Struct(try!(self.parse_record_struct_body(ParsePub::Yes)),
4925                                 ast::DUMMY_NODE_ID)
4926         // Tuple-style struct definition with optional where-clause.
4927         } else if self.token == token::OpenDelim(token::Paren) {
4928             let body = VariantData::Tuple(try!(self.parse_tuple_struct_body(ParsePub::Yes)),
4929                                           ast::DUMMY_NODE_ID);
4930             generics.where_clause = try!(self.parse_where_clause());
4931             try!(self.expect(&token::Semi));
4932             body
4933         } else {
4934             let token_str = self.this_token_to_string();
4935             return Err(self.fatal(&format!("expected `where`, `{{`, `(`, or `;` after struct \
4936                                             name, found `{}`", token_str)))
4937         };
4938
4939         Ok((class_name, ItemStruct(vdata, generics), None))
4940     }
4941
4942     pub fn parse_record_struct_body(&mut self,
4943                                     parse_pub: ParsePub)
4944                                     -> PResult<'a, Vec<StructField>> {
4945         let mut fields = Vec::new();
4946         if self.eat(&token::OpenDelim(token::Brace)) {
4947             while self.token != token::CloseDelim(token::Brace) {
4948                 fields.push(try!(self.parse_struct_decl_field(parse_pub)));
4949             }
4950
4951             self.bump();
4952         } else {
4953             let token_str = self.this_token_to_string();
4954             return Err(self.fatal(&format!("expected `where`, or `{{` after struct \
4955                                 name, found `{}`",
4956                                 token_str)));
4957         }
4958
4959         Ok(fields)
4960     }
4961
4962     pub fn parse_tuple_struct_body(&mut self,
4963                                    parse_pub: ParsePub)
4964                                    -> PResult<'a, Vec<StructField>> {
4965         // This is the case where we find `struct Foo<T>(T) where T: Copy;`
4966         // Unit like structs are handled in parse_item_struct function
4967         let fields = try!(self.parse_unspanned_seq(
4968             &token::OpenDelim(token::Paren),
4969             &token::CloseDelim(token::Paren),
4970             seq_sep_trailing_allowed(token::Comma),
4971             |p| {
4972                 let attrs = try!(p.parse_outer_attributes());
4973                 let lo = p.span.lo;
4974                 let struct_field_ = ast::StructField_ {
4975                     kind: UnnamedField (
4976                         if parse_pub == ParsePub::Yes {
4977                             try!(p.parse_visibility())
4978                         } else {
4979                             Inherited
4980                         }
4981                     ),
4982                     id: ast::DUMMY_NODE_ID,
4983                     ty: try!(p.parse_ty_sum()),
4984                     attrs: attrs,
4985                 };
4986                 Ok(spanned(lo, p.span.hi, struct_field_))
4987             }));
4988
4989         Ok(fields)
4990     }
4991
4992     /// Parse a structure field declaration
4993     pub fn parse_single_struct_field(&mut self,
4994                                      vis: Visibility,
4995                                      attrs: Vec<Attribute> )
4996                                      -> PResult<'a, StructField> {
4997         let a_var = try!(self.parse_name_and_ty(vis, attrs));
4998         match self.token {
4999             token::Comma => {
5000                 self.bump();
5001             }
5002             token::CloseDelim(token::Brace) => {}
5003             _ => {
5004                 let span = self.span;
5005                 let token_str = self.this_token_to_string();
5006                 return Err(self.span_fatal_help(span,
5007                                      &format!("expected `,`, or `}}`, found `{}`",
5008                                              token_str),
5009                                      "struct fields should be separated by commas"))
5010             }
5011         }
5012         Ok(a_var)
5013     }
5014
5015     /// Parse an element of a struct definition
5016     fn parse_struct_decl_field(&mut self, parse_pub: ParsePub) -> PResult<'a, StructField> {
5017
5018         let attrs = try!(self.parse_outer_attributes());
5019
5020         if self.eat_keyword(keywords::Pub) {
5021             if parse_pub == ParsePub::No {
5022                 let span = self.last_span;
5023                 self.span_err(span, "`pub` is not allowed here");
5024             }
5025             return self.parse_single_struct_field(Public, attrs);
5026         }
5027
5028         return self.parse_single_struct_field(Inherited, attrs);
5029     }
5030
5031     /// Parse visibility: PUB or nothing
5032     fn parse_visibility(&mut self) -> PResult<'a, Visibility> {
5033         if self.eat_keyword(keywords::Pub) { Ok(Public) }
5034         else { Ok(Inherited) }
5035     }
5036
5037     /// Given a termination token, parse all of the items in a module
5038     fn parse_mod_items(&mut self, term: &token::Token, inner_lo: BytePos) -> PResult<'a, Mod> {
5039         let mut items = vec![];
5040         while let Some(item) = try!(self.parse_item()) {
5041             items.push(item);
5042         }
5043
5044         if !self.eat(term) {
5045             let token_str = self.this_token_to_string();
5046             return Err(self.fatal(&format!("expected item, found `{}`", token_str)));
5047         }
5048
5049         let hi = if self.span == codemap::DUMMY_SP {
5050             inner_lo
5051         } else {
5052             self.last_span.hi
5053         };
5054
5055         Ok(ast::Mod {
5056             inner: mk_sp(inner_lo, hi),
5057             items: items
5058         })
5059     }
5060
5061     fn parse_item_const(&mut self, m: Option<Mutability>) -> PResult<'a, ItemInfo> {
5062         let id = try!(self.parse_ident());
5063         try!(self.expect(&token::Colon));
5064         let ty = try!(self.parse_ty_sum());
5065         try!(self.expect(&token::Eq));
5066         let e = try!(self.parse_expr());
5067         try!(self.commit_expr_expecting(&*e, token::Semi));
5068         let item = match m {
5069             Some(m) => ItemStatic(ty, m, e),
5070             None => ItemConst(ty, e),
5071         };
5072         Ok((id, item, None))
5073     }
5074
5075     /// Parse a `mod <foo> { ... }` or `mod <foo>;` item
5076     fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<'a, ItemInfo> {
5077         let id_span = self.span;
5078         let id = try!(self.parse_ident());
5079         if self.check(&token::Semi) {
5080             self.bump();
5081             // This mod is in an external file. Let's go get it!
5082             let (m, attrs) = try!(self.eval_src_mod(id, outer_attrs, id_span));
5083             Ok((id, m, Some(attrs)))
5084         } else {
5085             self.push_mod_path(id, outer_attrs);
5086             try!(self.expect(&token::OpenDelim(token::Brace)));
5087             let mod_inner_lo = self.span.lo;
5088             let old_owns_directory = self.owns_directory;
5089             self.owns_directory = true;
5090             let attrs = try!(self.parse_inner_attributes());
5091             let m = try!(self.parse_mod_items(&token::CloseDelim(token::Brace), mod_inner_lo));
5092             self.owns_directory = old_owns_directory;
5093             self.pop_mod_path();
5094             Ok((id, ItemMod(m), Some(attrs)))
5095         }
5096     }
5097
5098     fn push_mod_path(&mut self, id: Ident, attrs: &[Attribute]) {
5099         let default_path = self.id_to_interned_str(id);
5100         let file_path = match ::attr::first_attr_value_str_by_name(attrs, "path") {
5101             Some(d) => d,
5102             None => default_path,
5103         };
5104         self.mod_path_stack.push(file_path)
5105     }
5106
5107     fn pop_mod_path(&mut self) {
5108         self.mod_path_stack.pop().unwrap();
5109     }
5110
5111     pub fn submod_path_from_attr(attrs: &[ast::Attribute], dir_path: &Path) -> Option<PathBuf> {
5112         ::attr::first_attr_value_str_by_name(attrs, "path").map(|d| dir_path.join(&*d))
5113     }
5114
5115     /// Returns either a path to a module, or .
5116     pub fn default_submod_path(id: ast::Ident, dir_path: &Path, codemap: &CodeMap) -> ModulePath
5117     {
5118         let mod_name = id.to_string();
5119         let default_path_str = format!("{}.rs", mod_name);
5120         let secondary_path_str = format!("{}/mod.rs", mod_name);
5121         let default_path = dir_path.join(&default_path_str);
5122         let secondary_path = dir_path.join(&secondary_path_str);
5123         let default_exists = codemap.file_exists(&default_path);
5124         let secondary_exists = codemap.file_exists(&secondary_path);
5125
5126         let result = match (default_exists, secondary_exists) {
5127             (true, false) => Ok(ModulePathSuccess { path: default_path, owns_directory: false }),
5128             (false, true) => Ok(ModulePathSuccess { path: secondary_path, owns_directory: true }),
5129             (false, false) => Err(ModulePathError {
5130                 err_msg: format!("file not found for module `{}`", mod_name),
5131                 help_msg: format!("name the file either {} or {} inside the directory {:?}",
5132                                   default_path_str,
5133                                   secondary_path_str,
5134                                   dir_path.display()),
5135             }),
5136             (true, true) => Err(ModulePathError {
5137                 err_msg: format!("file for module `{}` found at both {} and {}",
5138                                  mod_name,
5139                                  default_path_str,
5140                                  secondary_path_str),
5141                 help_msg: "delete or rename one of them to remove the ambiguity".to_owned(),
5142             }),
5143         };
5144
5145         ModulePath {
5146             name: mod_name,
5147             path_exists: default_exists || secondary_exists,
5148             result: result,
5149         }
5150     }
5151
5152     fn submod_path(&mut self,
5153                    id: ast::Ident,
5154                    outer_attrs: &[ast::Attribute],
5155                    id_sp: Span) -> PResult<'a, ModulePathSuccess> {
5156         let mut prefix = PathBuf::from(&self.sess.codemap().span_to_filename(self.span));
5157         prefix.pop();
5158         let mut dir_path = prefix;
5159         for part in &self.mod_path_stack {
5160             dir_path.push(&**part);
5161         }
5162
5163         if let Some(p) = Parser::submod_path_from_attr(outer_attrs, &dir_path) {
5164             return Ok(ModulePathSuccess { path: p, owns_directory: true });
5165         }
5166
5167         let paths = Parser::default_submod_path(id, &dir_path, self.sess.codemap());
5168
5169         if !self.owns_directory {
5170             let mut err = self.diagnostic().struct_span_err(id_sp,
5171                 "cannot declare a new module at this location");
5172             let this_module = match self.mod_path_stack.last() {
5173                 Some(name) => name.to_string(),
5174                 None => self.root_module_name.as_ref().unwrap().clone(),
5175             };
5176             err.span_note(id_sp,
5177                           &format!("maybe move this module `{0}` to its own directory \
5178                                      via `{0}/mod.rs`",
5179                                     this_module));
5180             if paths.path_exists {
5181                 err.span_note(id_sp,
5182                               &format!("... or maybe `use` the module `{}` instead \
5183                                         of possibly redeclaring it",
5184                                        paths.name));
5185             }
5186             err.emit();
5187             self.abort_if_errors();
5188         }
5189
5190         match paths.result {
5191             Ok(succ) => Ok(succ),
5192             Err(err) => Err(self.span_fatal_help(id_sp, &err.err_msg, &err.help_msg)),
5193         }
5194     }
5195
5196     /// Read a module from a source file.
5197     fn eval_src_mod(&mut self,
5198                     id: ast::Ident,
5199                     outer_attrs: &[ast::Attribute],
5200                     id_sp: Span)
5201                     -> PResult<'a, (ast::Item_, Vec<ast::Attribute> )> {
5202         let ModulePathSuccess { path, owns_directory } = try!(self.submod_path(id,
5203                                                                                outer_attrs,
5204                                                                                id_sp));
5205
5206         self.eval_src_mod_from_path(path,
5207                                     owns_directory,
5208                                     id.to_string(),
5209                                     id_sp)
5210     }
5211
5212     fn eval_src_mod_from_path(&mut self,
5213                               path: PathBuf,
5214                               owns_directory: bool,
5215                               name: String,
5216                               id_sp: Span) -> PResult<'a, (ast::Item_, Vec<ast::Attribute> )> {
5217         let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut();
5218         match included_mod_stack.iter().position(|p| *p == path) {
5219             Some(i) => {
5220                 let mut err = String::from("circular modules: ");
5221                 let len = included_mod_stack.len();
5222                 for p in &included_mod_stack[i.. len] {
5223                     err.push_str(&p.to_string_lossy());
5224                     err.push_str(" -> ");
5225                 }
5226                 err.push_str(&path.to_string_lossy());
5227                 return Err(self.span_fatal(id_sp, &err[..]));
5228             }
5229             None => ()
5230         }
5231         included_mod_stack.push(path.clone());
5232         drop(included_mod_stack);
5233
5234         let mut p0 = new_sub_parser_from_file(self.sess,
5235                                               self.cfg.clone(),
5236                                               &path,
5237                                               owns_directory,
5238                                               Some(name),
5239                                               id_sp);
5240         let mod_inner_lo = p0.span.lo;
5241         let mod_attrs = try!(p0.parse_inner_attributes());
5242         let m0 = try!(p0.parse_mod_items(&token::Eof, mod_inner_lo));
5243         self.sess.included_mod_stack.borrow_mut().pop();
5244         Ok((ast::ItemMod(m0), mod_attrs))
5245     }
5246
5247     /// Parse a function declaration from a foreign module
5248     fn parse_item_foreign_fn(&mut self, vis: ast::Visibility, lo: BytePos,
5249                              attrs: Vec<Attribute>) -> PResult<'a, P<ForeignItem>> {
5250         try!(self.expect_keyword(keywords::Fn));
5251
5252         let (ident, mut generics) = try!(self.parse_fn_header());
5253         let decl = try!(self.parse_fn_decl(true));
5254         generics.where_clause = try!(self.parse_where_clause());
5255         let hi = self.span.hi;
5256         try!(self.expect(&token::Semi));
5257         Ok(P(ast::ForeignItem {
5258             ident: ident,
5259             attrs: attrs,
5260             node: ForeignItemFn(decl, generics),
5261             id: ast::DUMMY_NODE_ID,
5262             span: mk_sp(lo, hi),
5263             vis: vis
5264         }))
5265     }
5266
5267     /// Parse a static item from a foreign module
5268     fn parse_item_foreign_static(&mut self, vis: ast::Visibility, lo: BytePos,
5269                                  attrs: Vec<Attribute>) -> PResult<'a, P<ForeignItem>> {
5270         try!(self.expect_keyword(keywords::Static));
5271         let mutbl = self.eat_keyword(keywords::Mut);
5272
5273         let ident = try!(self.parse_ident());
5274         try!(self.expect(&token::Colon));
5275         let ty = try!(self.parse_ty_sum());
5276         let hi = self.span.hi;
5277         try!(self.expect(&token::Semi));
5278         Ok(P(ForeignItem {
5279             ident: ident,
5280             attrs: attrs,
5281             node: ForeignItemStatic(ty, mutbl),
5282             id: ast::DUMMY_NODE_ID,
5283             span: mk_sp(lo, hi),
5284             vis: vis
5285         }))
5286     }
5287
5288     /// Parse extern crate links
5289     ///
5290     /// # Examples
5291     ///
5292     /// extern crate foo;
5293     /// extern crate bar as foo;
5294     fn parse_item_extern_crate(&mut self,
5295                                lo: BytePos,
5296                                visibility: Visibility,
5297                                attrs: Vec<Attribute>)
5298                                 -> PResult<'a, P<Item>> {
5299
5300         let crate_name = try!(self.parse_ident());
5301         let (maybe_path, ident) = if let Some(ident) = try!(self.parse_rename()) {
5302             (Some(crate_name.name), ident)
5303         } else {
5304             (None, crate_name)
5305         };
5306         try!(self.expect(&token::Semi));
5307
5308         let last_span = self.last_span;
5309
5310         if visibility == ast::Public {
5311             self.span_warn(mk_sp(lo, last_span.hi),
5312                            "`pub extern crate` does not work as expected and should not be used. \
5313                             Likely to become an error. Prefer `extern crate` and `pub use`.");
5314         }
5315
5316         Ok(self.mk_item(lo,
5317                         last_span.hi,
5318                         ident,
5319                         ItemExternCrate(maybe_path),
5320                         visibility,
5321                         attrs))
5322     }
5323
5324     /// Parse `extern` for foreign ABIs
5325     /// modules.
5326     ///
5327     /// `extern` is expected to have been
5328     /// consumed before calling this method
5329     ///
5330     /// # Examples:
5331     ///
5332     /// extern "C" {}
5333     /// extern {}
5334     fn parse_item_foreign_mod(&mut self,
5335                               lo: BytePos,
5336                               opt_abi: Option<abi::Abi>,
5337                               visibility: Visibility,
5338                               mut attrs: Vec<Attribute>)
5339                               -> PResult<'a, P<Item>> {
5340         try!(self.expect(&token::OpenDelim(token::Brace)));
5341
5342         let abi = opt_abi.unwrap_or(abi::C);
5343
5344         attrs.extend(try!(self.parse_inner_attributes()));
5345
5346         let mut foreign_items = vec![];
5347         while let Some(item) = try!(self.parse_foreign_item()) {
5348             foreign_items.push(item);
5349         }
5350         try!(self.expect(&token::CloseDelim(token::Brace)));
5351
5352         let last_span = self.last_span;
5353         let m = ast::ForeignMod {
5354             abi: abi,
5355             items: foreign_items
5356         };
5357         Ok(self.mk_item(lo,
5358                      last_span.hi,
5359                      special_idents::invalid,
5360                      ItemForeignMod(m),
5361                      visibility,
5362                      attrs))
5363     }
5364
5365     /// Parse type Foo = Bar;
5366     fn parse_item_type(&mut self) -> PResult<'a, ItemInfo> {
5367         let ident = try!(self.parse_ident());
5368         let mut tps = try!(self.parse_generics());
5369         tps.where_clause = try!(self.parse_where_clause());
5370         try!(self.expect(&token::Eq));
5371         let ty = try!(self.parse_ty_sum());
5372         try!(self.expect(&token::Semi));
5373         Ok((ident, ItemTy(ty, tps), None))
5374     }
5375
5376     /// Parse the part of an "enum" decl following the '{'
5377     fn parse_enum_def(&mut self, _generics: &ast::Generics) -> PResult<'a, EnumDef> {
5378         let mut variants = Vec::new();
5379         let mut all_nullary = true;
5380         let mut any_disr = None;
5381         while self.token != token::CloseDelim(token::Brace) {
5382             let variant_attrs = try!(self.parse_outer_attributes());
5383             let vlo = self.span.lo;
5384
5385             let struct_def;
5386             let mut disr_expr = None;
5387             let ident = try!(self.parse_ident());
5388             if self.check(&token::OpenDelim(token::Brace)) {
5389                 // Parse a struct variant.
5390                 all_nullary = false;
5391                 struct_def = VariantData::Struct(try!(self.parse_record_struct_body(ParsePub::No)),
5392                                                  ast::DUMMY_NODE_ID);
5393             } else if self.check(&token::OpenDelim(token::Paren)) {
5394                 all_nullary = false;
5395                 struct_def = VariantData::Tuple(try!(self.parse_tuple_struct_body(ParsePub::No)),
5396                                                 ast::DUMMY_NODE_ID);
5397             } else if self.eat(&token::Eq) {
5398                 disr_expr = Some(try!(self.parse_expr()));
5399                 any_disr = disr_expr.as_ref().map(|expr| expr.span);
5400                 struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
5401             } else {
5402                 struct_def = VariantData::Unit(ast::DUMMY_NODE_ID);
5403             }
5404
5405             let vr = ast::Variant_ {
5406                 name: ident,
5407                 attrs: variant_attrs,
5408                 data: struct_def,
5409                 disr_expr: disr_expr,
5410             };
5411             variants.push(P(spanned(vlo, self.last_span.hi, vr)));
5412
5413             if !self.eat(&token::Comma) { break; }
5414         }
5415         try!(self.expect(&token::CloseDelim(token::Brace)));
5416         match any_disr {
5417             Some(disr_span) if !all_nullary =>
5418                 self.span_err(disr_span,
5419                     "discriminator values can only be used with a c-like enum"),
5420             _ => ()
5421         }
5422
5423         Ok(ast::EnumDef { variants: variants })
5424     }
5425
5426     /// Parse an "enum" declaration
5427     fn parse_item_enum(&mut self) -> PResult<'a, ItemInfo> {
5428         let id = try!(self.parse_ident());
5429         let mut generics = try!(self.parse_generics());
5430         generics.where_clause = try!(self.parse_where_clause());
5431         try!(self.expect(&token::OpenDelim(token::Brace)));
5432
5433         let enum_definition = try!(self.parse_enum_def(&generics));
5434         Ok((id, ItemEnum(enum_definition, generics), None))
5435     }
5436
5437     /// Parses a string as an ABI spec on an extern type or module. Consumes
5438     /// the `extern` keyword, if one is found.
5439     fn parse_opt_abi(&mut self) -> PResult<'a, Option<abi::Abi>> {
5440         match self.token {
5441             token::Literal(token::Str_(s), suf) | token::Literal(token::StrRaw(s, _), suf) => {
5442                 let sp = self.span;
5443                 self.expect_no_suffix(sp, "ABI spec", suf);
5444                 self.bump();
5445                 match abi::lookup(&s.as_str()) {
5446                     Some(abi) => Ok(Some(abi)),
5447                     None => {
5448                         let last_span = self.last_span;
5449                         self.span_err(
5450                             last_span,
5451                             &format!("invalid ABI: expected one of [{}], \
5452                                      found `{}`",
5453                                     abi::all_names().join(", "),
5454                                     s));
5455                         Ok(None)
5456                     }
5457                 }
5458             }
5459
5460             _ => Ok(None),
5461         }
5462     }
5463
5464     /// Parse one of the items allowed by the flags.
5465     /// NB: this function no longer parses the items inside an
5466     /// extern crate.
5467     fn parse_item_(&mut self, attrs: Vec<Attribute>,
5468                    macros_allowed: bool, attributes_allowed: bool) -> PResult<'a, Option<P<Item>>> {
5469         let nt_item = match self.token {
5470             token::Interpolated(token::NtItem(ref item)) => {
5471                 Some((**item).clone())
5472             }
5473             _ => None
5474         };
5475         match nt_item {
5476             Some(mut item) => {
5477                 self.bump();
5478                 let mut attrs = attrs;
5479                 mem::swap(&mut item.attrs, &mut attrs);
5480                 item.attrs.extend(attrs);
5481                 return Ok(Some(P(item)));
5482             }
5483             None => {}
5484         }
5485
5486         let lo = self.span.lo;
5487
5488         let visibility = try!(self.parse_visibility());
5489
5490         if self.eat_keyword(keywords::Use) {
5491             // USE ITEM
5492             let item_ = ItemUse(try!(self.parse_view_path()));
5493             try!(self.expect(&token::Semi));
5494
5495             let last_span = self.last_span;
5496             let item = self.mk_item(lo,
5497                                     last_span.hi,
5498                                     token::special_idents::invalid,
5499                                     item_,
5500                                     visibility,
5501                                     attrs);
5502             return Ok(Some(item));
5503         }
5504
5505         if self.eat_keyword(keywords::Extern) {
5506             if self.eat_keyword(keywords::Crate) {
5507                 return Ok(Some(try!(self.parse_item_extern_crate(lo, visibility, attrs))));
5508             }
5509
5510             let opt_abi = try!(self.parse_opt_abi());
5511
5512             if self.eat_keyword(keywords::Fn) {
5513                 // EXTERN FUNCTION ITEM
5514                 let abi = opt_abi.unwrap_or(abi::C);
5515                 let (ident, item_, extra_attrs) =
5516                     try!(self.parse_item_fn(Unsafety::Normal, Constness::NotConst, abi));
5517                 let last_span = self.last_span;
5518                 let item = self.mk_item(lo,
5519                                         last_span.hi,
5520                                         ident,
5521                                         item_,
5522                                         visibility,
5523                                         maybe_append(attrs, extra_attrs));
5524                 return Ok(Some(item));
5525             } else if self.check(&token::OpenDelim(token::Brace)) {
5526                 return Ok(Some(try!(self.parse_item_foreign_mod(lo, opt_abi, visibility, attrs))));
5527             }
5528
5529             try!(self.unexpected());
5530         }
5531
5532         if self.eat_keyword(keywords::Static) {
5533             // STATIC ITEM
5534             let m = if self.eat_keyword(keywords::Mut) {MutMutable} else {MutImmutable};
5535             let (ident, item_, extra_attrs) = try!(self.parse_item_const(Some(m)));
5536             let last_span = self.last_span;
5537             let item = self.mk_item(lo,
5538                                     last_span.hi,
5539                                     ident,
5540                                     item_,
5541                                     visibility,
5542                                     maybe_append(attrs, extra_attrs));
5543             return Ok(Some(item));
5544         }
5545         if self.eat_keyword(keywords::Const) {
5546             if self.check_keyword(keywords::Fn)
5547                 || (self.check_keyword(keywords::Unsafe)
5548                     && self.look_ahead(1, |t| t.is_keyword(keywords::Fn))) {
5549                 // CONST FUNCTION ITEM
5550                 let unsafety = if self.eat_keyword(keywords::Unsafe) {
5551                     Unsafety::Unsafe
5552                 } else {
5553                     Unsafety::Normal
5554                 };
5555                 self.bump();
5556                 let (ident, item_, extra_attrs) =
5557                     try!(self.parse_item_fn(unsafety, Constness::Const, abi::Rust));
5558                 let last_span = self.last_span;
5559                 let item = self.mk_item(lo,
5560                                         last_span.hi,
5561                                         ident,
5562                                         item_,
5563                                         visibility,
5564                                         maybe_append(attrs, extra_attrs));
5565                 return Ok(Some(item));
5566             }
5567
5568             // CONST ITEM
5569             if self.eat_keyword(keywords::Mut) {
5570                 let last_span = self.last_span;
5571                 self.diagnostic().struct_span_err(last_span, "const globals cannot be mutable")
5572                                  .fileline_help(last_span, "did you mean to declare a static?")
5573                                  .emit();
5574             }
5575             let (ident, item_, extra_attrs) = try!(self.parse_item_const(None));
5576             let last_span = self.last_span;
5577             let item = self.mk_item(lo,
5578                                     last_span.hi,
5579                                     ident,
5580                                     item_,
5581                                     visibility,
5582                                     maybe_append(attrs, extra_attrs));
5583             return Ok(Some(item));
5584         }
5585         if self.check_keyword(keywords::Unsafe) &&
5586             self.look_ahead(1, |t| t.is_keyword(keywords::Trait))
5587         {
5588             // UNSAFE TRAIT ITEM
5589             try!(self.expect_keyword(keywords::Unsafe));
5590             try!(self.expect_keyword(keywords::Trait));
5591             let (ident, item_, extra_attrs) =
5592                 try!(self.parse_item_trait(ast::Unsafety::Unsafe));
5593             let last_span = self.last_span;
5594             let item = self.mk_item(lo,
5595                                     last_span.hi,
5596                                     ident,
5597                                     item_,
5598                                     visibility,
5599                                     maybe_append(attrs, extra_attrs));
5600             return Ok(Some(item));
5601         }
5602         if self.check_keyword(keywords::Unsafe) &&
5603             self.look_ahead(1, |t| t.is_keyword(keywords::Impl))
5604         {
5605             // IMPL ITEM
5606             try!(self.expect_keyword(keywords::Unsafe));
5607             try!(self.expect_keyword(keywords::Impl));
5608             let (ident, item_, extra_attrs) = try!(self.parse_item_impl(ast::Unsafety::Unsafe));
5609             let last_span = self.last_span;
5610             let item = self.mk_item(lo,
5611                                     last_span.hi,
5612                                     ident,
5613                                     item_,
5614                                     visibility,
5615                                     maybe_append(attrs, extra_attrs));
5616             return Ok(Some(item));
5617         }
5618         if self.check_keyword(keywords::Fn) {
5619             // FUNCTION ITEM
5620             self.bump();
5621             let (ident, item_, extra_attrs) =
5622                 try!(self.parse_item_fn(Unsafety::Normal, Constness::NotConst, abi::Rust));
5623             let last_span = self.last_span;
5624             let item = self.mk_item(lo,
5625                                     last_span.hi,
5626                                     ident,
5627                                     item_,
5628                                     visibility,
5629                                     maybe_append(attrs, extra_attrs));
5630             return Ok(Some(item));
5631         }
5632         if self.check_keyword(keywords::Unsafe)
5633             && self.look_ahead(1, |t| *t != token::OpenDelim(token::Brace)) {
5634             // UNSAFE FUNCTION ITEM
5635             self.bump();
5636             let abi = if self.eat_keyword(keywords::Extern) {
5637                 try!(self.parse_opt_abi()).unwrap_or(abi::C)
5638             } else {
5639                 abi::Rust
5640             };
5641             try!(self.expect_keyword(keywords::Fn));
5642             let (ident, item_, extra_attrs) =
5643                 try!(self.parse_item_fn(Unsafety::Unsafe, Constness::NotConst, abi));
5644             let last_span = self.last_span;
5645             let item = self.mk_item(lo,
5646                                     last_span.hi,
5647                                     ident,
5648                                     item_,
5649                                     visibility,
5650                                     maybe_append(attrs, extra_attrs));
5651             return Ok(Some(item));
5652         }
5653         if self.eat_keyword(keywords::Mod) {
5654             // MODULE ITEM
5655             let (ident, item_, extra_attrs) =
5656                 try!(self.parse_item_mod(&attrs[..]));
5657             let last_span = self.last_span;
5658             let item = self.mk_item(lo,
5659                                     last_span.hi,
5660                                     ident,
5661                                     item_,
5662                                     visibility,
5663                                     maybe_append(attrs, extra_attrs));
5664             return Ok(Some(item));
5665         }
5666         if self.eat_keyword(keywords::Type) {
5667             // TYPE ITEM
5668             let (ident, item_, extra_attrs) = try!(self.parse_item_type());
5669             let last_span = self.last_span;
5670             let item = self.mk_item(lo,
5671                                     last_span.hi,
5672                                     ident,
5673                                     item_,
5674                                     visibility,
5675                                     maybe_append(attrs, extra_attrs));
5676             return Ok(Some(item));
5677         }
5678         if self.eat_keyword(keywords::Enum) {
5679             // ENUM ITEM
5680             let (ident, item_, extra_attrs) = try!(self.parse_item_enum());
5681             let last_span = self.last_span;
5682             let item = self.mk_item(lo,
5683                                     last_span.hi,
5684                                     ident,
5685                                     item_,
5686                                     visibility,
5687                                     maybe_append(attrs, extra_attrs));
5688             return Ok(Some(item));
5689         }
5690         if self.eat_keyword(keywords::Trait) {
5691             // TRAIT ITEM
5692             let (ident, item_, extra_attrs) =
5693                 try!(self.parse_item_trait(ast::Unsafety::Normal));
5694             let last_span = self.last_span;
5695             let item = self.mk_item(lo,
5696                                     last_span.hi,
5697                                     ident,
5698                                     item_,
5699                                     visibility,
5700                                     maybe_append(attrs, extra_attrs));
5701             return Ok(Some(item));
5702         }
5703         if self.eat_keyword(keywords::Impl) {
5704             // IMPL ITEM
5705             let (ident, item_, extra_attrs) = try!(self.parse_item_impl(ast::Unsafety::Normal));
5706             let last_span = self.last_span;
5707             let item = self.mk_item(lo,
5708                                     last_span.hi,
5709                                     ident,
5710                                     item_,
5711                                     visibility,
5712                                     maybe_append(attrs, extra_attrs));
5713             return Ok(Some(item));
5714         }
5715         if self.eat_keyword(keywords::Struct) {
5716             // STRUCT ITEM
5717             let (ident, item_, extra_attrs) = try!(self.parse_item_struct());
5718             let last_span = self.last_span;
5719             let item = self.mk_item(lo,
5720                                     last_span.hi,
5721                                     ident,
5722                                     item_,
5723                                     visibility,
5724                                     maybe_append(attrs, extra_attrs));
5725             return Ok(Some(item));
5726         }
5727         self.parse_macro_use_or_failure(attrs,macros_allowed,attributes_allowed,lo,visibility)
5728     }
5729
5730     /// Parse a foreign item.
5731     fn parse_foreign_item(&mut self) -> PResult<'a, Option<P<ForeignItem>>> {
5732         let attrs = try!(self.parse_outer_attributes());
5733         let lo = self.span.lo;
5734         let visibility = try!(self.parse_visibility());
5735
5736         if self.check_keyword(keywords::Static) {
5737             // FOREIGN STATIC ITEM
5738             return Ok(Some(try!(self.parse_item_foreign_static(visibility, lo, attrs))));
5739         }
5740         if self.check_keyword(keywords::Fn) || self.check_keyword(keywords::Unsafe) {
5741             // FOREIGN FUNCTION ITEM
5742             return Ok(Some(try!(self.parse_item_foreign_fn(visibility, lo, attrs))));
5743         }
5744
5745         // FIXME #5668: this will occur for a macro invocation:
5746         match try!(self.parse_macro_use_or_failure(attrs, true, false, lo, visibility)) {
5747             Some(item) => {
5748                 return Err(self.span_fatal(item.span, "macros cannot expand to foreign items"));
5749             }
5750             None => Ok(None)
5751         }
5752     }
5753
5754     /// This is the fall-through for parsing items.
5755     fn parse_macro_use_or_failure(
5756         &mut self,
5757         attrs: Vec<Attribute> ,
5758         macros_allowed: bool,
5759         attributes_allowed: bool,
5760         lo: BytePos,
5761         visibility: Visibility
5762     ) -> PResult<'a, Option<P<Item>>> {
5763         if macros_allowed && !self.token.is_any_keyword()
5764                 && self.look_ahead(1, |t| *t == token::Not)
5765                 && (self.look_ahead(2, |t| t.is_plain_ident())
5766                     || self.look_ahead(2, |t| *t == token::OpenDelim(token::Paren))
5767                     || self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))) {
5768             // MACRO INVOCATION ITEM
5769
5770             let last_span = self.last_span;
5771             self.complain_if_pub_macro(visibility, last_span);
5772
5773             let mac_lo = self.span.lo;
5774
5775             // item macro.
5776             let pth = try!(self.parse_path(NoTypesAllowed));
5777             try!(self.expect(&token::Not));
5778
5779             // a 'special' identifier (like what `macro_rules!` uses)
5780             // is optional. We should eventually unify invoc syntax
5781             // and remove this.
5782             let id = if self.token.is_plain_ident() {
5783                 try!(self.parse_ident())
5784             } else {
5785                 token::special_idents::invalid // no special identifier
5786             };
5787             // eat a matched-delimiter token tree:
5788             let delim = try!(self.expect_open_delim());
5789             let tts = try!(self.parse_seq_to_end(&token::CloseDelim(delim),
5790                                             seq_sep_none(),
5791                                             |p| p.parse_token_tree()));
5792             // single-variant-enum... :
5793             let m = Mac_ { path: pth, tts: tts, ctxt: EMPTY_CTXT };
5794             let m: ast::Mac = codemap::Spanned { node: m,
5795                                              span: mk_sp(mac_lo,
5796                                                          self.last_span.hi) };
5797
5798             if delim != token::Brace {
5799                 if !self.eat(&token::Semi) {
5800                     let last_span = self.last_span;
5801                     self.span_err(last_span,
5802                                   "macros that expand to items must either \
5803                                    be surrounded with braces or followed by \
5804                                    a semicolon");
5805                 }
5806             }
5807
5808             let item_ = ItemMac(m);
5809             let last_span = self.last_span;
5810             let item = self.mk_item(lo,
5811                                     last_span.hi,
5812                                     id,
5813                                     item_,
5814                                     visibility,
5815                                     attrs);
5816             return Ok(Some(item));
5817         }
5818
5819         // FAILURE TO PARSE ITEM
5820         match visibility {
5821             Inherited => {}
5822             Public => {
5823                 let last_span = self.last_span;
5824                 return Err(self.span_fatal(last_span, "unmatched visibility `pub`"));
5825             }
5826         }
5827
5828         if !attributes_allowed && !attrs.is_empty() {
5829             self.expected_item_err(&attrs);
5830         }
5831         Ok(None)
5832     }
5833
5834     pub fn parse_item(&mut self) -> PResult<'a, Option<P<Item>>> {
5835         let attrs = try!(self.parse_outer_attributes());
5836         self.parse_item_(attrs, true, false)
5837     }
5838
5839
5840     /// Matches view_path : MOD? non_global_path as IDENT
5841     /// | MOD? non_global_path MOD_SEP LBRACE RBRACE
5842     /// | MOD? non_global_path MOD_SEP LBRACE ident_seq RBRACE
5843     /// | MOD? non_global_path MOD_SEP STAR
5844     /// | MOD? non_global_path
5845     fn parse_view_path(&mut self) -> PResult<'a, P<ViewPath>> {
5846         let lo = self.span.lo;
5847
5848         // Allow a leading :: because the paths are absolute either way.
5849         // This occurs with "use $crate::..." in macros.
5850         self.eat(&token::ModSep);
5851
5852         if self.check(&token::OpenDelim(token::Brace)) {
5853             // use {foo,bar}
5854             let idents = try!(self.parse_unspanned_seq(
5855                 &token::OpenDelim(token::Brace),
5856                 &token::CloseDelim(token::Brace),
5857                 seq_sep_trailing_allowed(token::Comma),
5858                 |p| p.parse_path_list_item()));
5859             let path = ast::Path {
5860                 span: mk_sp(lo, self.span.hi),
5861                 global: false,
5862                 segments: Vec::new()
5863             };
5864             return Ok(P(spanned(lo, self.span.hi, ViewPathList(path, idents))));
5865         }
5866
5867         let first_ident = try!(self.parse_ident());
5868         let mut path = vec!(first_ident);
5869         if let token::ModSep = self.token {
5870             // foo::bar or foo::{a,b,c} or foo::*
5871             while self.check(&token::ModSep) {
5872                 self.bump();
5873
5874                 match self.token {
5875                   token::Ident(..) => {
5876                     let ident = try!(self.parse_ident());
5877                     path.push(ident);
5878                   }
5879
5880                   // foo::bar::{a,b,c}
5881                   token::OpenDelim(token::Brace) => {
5882                     let idents = try!(self.parse_unspanned_seq(
5883                         &token::OpenDelim(token::Brace),
5884                         &token::CloseDelim(token::Brace),
5885                         seq_sep_trailing_allowed(token::Comma),
5886                         |p| p.parse_path_list_item()
5887                     ));
5888                     let path = ast::Path {
5889                         span: mk_sp(lo, self.span.hi),
5890                         global: false,
5891                         segments: path.into_iter().map(|identifier| {
5892                             ast::PathSegment {
5893                                 identifier: identifier,
5894                                 parameters: ast::PathParameters::none(),
5895                             }
5896                         }).collect()
5897                     };
5898                     return Ok(P(spanned(lo, self.span.hi, ViewPathList(path, idents))));
5899                   }
5900
5901                   // foo::bar::*
5902                   token::BinOp(token::Star) => {
5903                     self.bump();
5904                     let path = ast::Path {
5905                         span: mk_sp(lo, self.span.hi),
5906                         global: false,
5907                         segments: path.into_iter().map(|identifier| {
5908                             ast::PathSegment {
5909                                 identifier: identifier,
5910                                 parameters: ast::PathParameters::none(),
5911                             }
5912                         }).collect()
5913                     };
5914                     return Ok(P(spanned(lo, self.span.hi, ViewPathGlob(path))));
5915                   }
5916
5917                   // fall-through for case foo::bar::;
5918                   token::Semi => {
5919                     self.span_err(self.span, "expected identifier or `{` or `*`, found `;`");
5920                   }
5921
5922                   _ => break
5923                 }
5924             }
5925         }
5926         let mut rename_to = path[path.len() - 1];
5927         let path = ast::Path {
5928             span: mk_sp(lo, self.last_span.hi),
5929             global: false,
5930             segments: path.into_iter().map(|identifier| {
5931                 ast::PathSegment {
5932                     identifier: identifier,
5933                     parameters: ast::PathParameters::none(),
5934                 }
5935             }).collect()
5936         };
5937         rename_to = try!(self.parse_rename()).unwrap_or(rename_to);
5938         Ok(P(spanned(lo, self.last_span.hi, ViewPathSimple(rename_to, path))))
5939     }
5940
5941     fn parse_rename(&mut self) -> PResult<'a, Option<Ident>> {
5942         if self.eat_keyword(keywords::As) {
5943             self.parse_ident().map(Some)
5944         } else {
5945             Ok(None)
5946         }
5947     }
5948
5949     /// Parses a source module as a crate. This is the main
5950     /// entry point for the parser.
5951     pub fn parse_crate_mod(&mut self) -> PResult<'a, Crate> {
5952         let lo = self.span.lo;
5953         Ok(ast::Crate {
5954             attrs: try!(self.parse_inner_attributes()),
5955             module: try!(self.parse_mod_items(&token::Eof, lo)),
5956             config: self.cfg.clone(),
5957             span: mk_sp(lo, self.span.lo),
5958             exported_macros: Vec::new(),
5959         })
5960     }
5961
5962     pub fn parse_optional_str(&mut self)
5963                               -> Option<(InternedString,
5964                                          ast::StrStyle,
5965                                          Option<ast::Name>)> {
5966         let ret = match self.token {
5967             token::Literal(token::Str_(s), suf) => {
5968                 (self.id_to_interned_str(ast::Ident::with_empty_ctxt(s)), ast::CookedStr, suf)
5969             }
5970             token::Literal(token::StrRaw(s, n), suf) => {
5971                 (self.id_to_interned_str(ast::Ident::with_empty_ctxt(s)), ast::RawStr(n), suf)
5972             }
5973             _ => return None
5974         };
5975         self.bump();
5976         Some(ret)
5977     }
5978
5979     pub fn parse_str(&mut self) -> PResult<'a, (InternedString, StrStyle)> {
5980         match self.parse_optional_str() {
5981             Some((s, style, suf)) => {
5982                 let sp = self.last_span;
5983                 self.expect_no_suffix(sp, "string literal", suf);
5984                 Ok((s, style))
5985             }
5986             _ =>  Err(self.fatal("expected string literal"))
5987         }
5988     }
5989 }