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