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