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