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, BiGt, Block};
  19 use ast::{BlockCheckMode, CaptureByRef, CaptureByValue, CaptureClause};
  20 use ast::{Constness, ConstImplItem, 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};
  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, 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_, MacInvocTT, MatchSource};
  41 use ast::{MutTy, BiMul, Mutability};
  42 use ast::{MethodImplItem, NamedField, UnNeg, NoReturn, UnNot};
  43 use ast::{Pat, PatBox, PatEnum, PatIdent, PatLit, PatQPath, PatMac, PatRange};
  44 use ast::{PatRegion, PatStruct, PatTup, PatVec, PatWild, PatWildMulti};
  45 use ast::PatWildSingle;
  46 use ast::{PolyTraitRef, QSelf};
  47 use ast::{Return, BiShl, BiShr, Stmt, StmtDecl};
  48 use ast::{StmtExpr, StmtSemi, StmtMac, StructDef, StructField};
  49 use ast::{StructVariantKind, BiSub, StrStyle};
  50 use ast::{SelfExplicit, SelfRegion, SelfStatic, SelfValue};
  51 use ast::{Delimited, SequenceRepetition, TokenTree, TraitItem, TraitRef};
  52 use ast::{TtDelimited, TtSequence, TtToken};
  53 use ast::{TupleVariantKind, Ty, Ty_, TypeBinding};
  54 use ast::{TyMac};
  55 use ast::{TyFixedLengthVec, TyBareFn, TyTypeof, TyInfer};
  56 use ast::{TyParam, TyParamBound, TyParen, TyPath, TyPolyTraitRef, TyPtr};
  57 use ast::{TyRptr, TyTup, TyU32, TyVec, UnUniq};
  58 use ast::{TypeImplItem, TypeTraitItem};
  59 use ast::{UnnamedField, UnsafeBlock};
  60 use ast::{ViewPath, ViewPathGlob, ViewPathList, ViewPathSimple};
  61 use ast::{Visibility, WhereClause};
  62 use ast;
  63 use ast_util::{self, AS_PREC, ident_to_path, operator_prec};
  64 use codemap::{self, Span, BytePos, Spanned, spanned, mk_sp, CodeMap};
  65 use diagnostic;
  66 use ext::tt::macro_parser;
  67 use parse;
  68 use parse::attr::ParserAttr;
  69 use parse::classify;
  70 use parse::common::{SeqSep, seq_sep_none, seq_sep_trailing_allowed};
  71 use parse::lexer::{Reader, TokenAndSpan};
  72 use parse::obsolete::{ParserObsoleteMethods, ObsoleteSyntax};
  73 use parse::token::{self, MatchNt, SubstNt, SpecialVarNt, InternedString};
  74 use parse::token::{keywords, special_idents, SpecialMacroVar};
  75 use parse::{new_sub_parser_from_file, ParseSess};
  76 use print::pprust;
  77 use ptr::P;
  78 use owned_slice::OwnedSlice;
  79 use parse::PResult;
  80 use diagnostic::FatalError;
  81
  82 use std::collections::HashSet;
  83 use std::io::prelude::*;
  84 use std::mem;
  85 use std::path::{Path, PathBuf};
  86 use std::rc::Rc;
  87 use std::slice;
  88
  89 bitflags! {
  90     flags Restrictions: u8 {
  91         const RESTRICTION_STMT_EXPR         = 1 << 0,
  92         const RESTRICTION_NO_STRUCT_LITERAL = 1 << 1,
  93     }
  94 }
  95
  96 type ItemInfo = (Ident, Item_, Option<Vec<Attribute> >);
  97
  98 /// How to parse a path. There are four different kinds of paths, all of which
  99 /// are parsed somewhat differently.
 100 #[derive(Copy, Clone, PartialEq)]
 101 pub enum PathParsingMode {
 102     /// A path with no type parameters; e.g. `foo::bar::Baz`
 103     NoTypesAllowed,
 104     /// A path with a lifetime and type parameters, with no double colons
 105     /// before the type parameters; e.g. `foo::bar<'a>::Baz<T>`
 106     LifetimeAndTypesWithoutColons,
 107     /// A path with a lifetime and type parameters with double colons before
 108     /// the type parameters; e.g. `foo::bar::<'a>::Baz::<T>`
 109     LifetimeAndTypesWithColons,
 110 }
 111
 112 /// How to parse a bound, whether to allow bound modifiers such as `?`.
 113 #[derive(Copy, Clone, PartialEq)]
 114 pub enum BoundParsingMode {
 115     Bare,
 116     Modified,
 117 }
 118
 119 /// Possibly accept an `token::Interpolated` expression (a pre-parsed expression
 120 /// dropped into the token stream, which happens while parsing the result of
 121 /// macro expansion). Placement of these is not as complex as I feared it would
 122 /// be. The important thing is to make sure that lookahead doesn't balk at
 123 /// `token::Interpolated` tokens.
 124 macro_rules! maybe_whole_expr {
 125     ($p:expr) => (
 126         {
 127             let found = match $p.token {
 128                 token::Interpolated(token::NtExpr(ref e)) => {
 129                     Some((*e).clone())
 130                 }
 131                 token::Interpolated(token::NtPath(_)) => {
 132                     // FIXME: The following avoids an issue with lexical borrowck scopes,
 133                     // but the clone is unfortunate.
 134                     let pt = match $p.token {
 135                         token::Interpolated(token::NtPath(ref pt)) => (**pt).clone(),
 136                         _ => unreachable!()
 137                     };
 138                     let span = $p.span;
 139                     Some($p.mk_expr(span.lo, span.hi, ExprPath(None, pt)))
 140                 }
 141                 token::Interpolated(token::NtBlock(_)) => {
 142                     // FIXME: The following avoids an issue with lexical borrowck scopes,
 143                     // but the clone is unfortunate.
 144                     let b = match $p.token {
 145                         token::Interpolated(token::NtBlock(ref b)) => (*b).clone(),
 146                         _ => unreachable!()
 147                     };
 148                     let span = $p.span;
 149                     Some($p.mk_expr(span.lo, span.hi, ExprBlock(b)))
 150                 }
 151                 _ => None
 152             };
 153             match found {
 154                 Some(e) => {
 155                     try!($p.bump());
 156                     return Ok(e);
 157                 }
 158                 None => ()
 159             }
 160         }
 161     )
 162 }
 163
 164 /// As maybe_whole_expr, but for things other than expressions
 165 macro_rules! maybe_whole {
 166     ($p:expr, $constructor:ident) => (
 167         {
 168             let found = match ($p).token {
 169                 token::Interpolated(token::$constructor(_)) => {
 170                     Some(try!(($p).bump_and_get()))
 171                 }
 172                 _ => None
 173             };
 174             if let Some(token::Interpolated(token::$constructor(x))) = found {
 175                 return Ok(x.clone());
 176             }
 177         }
 178     );
 179     (no_clone $p:expr, $constructor:ident) => (
 180         {
 181             let found = match ($p).token {
 182                 token::Interpolated(token::$constructor(_)) => {
 183                     Some(try!(($p).bump_and_get()))
 184                 }
 185                 _ => None
 186             };
 187             if let Some(token::Interpolated(token::$constructor(x))) = found {
 188                 return Ok(x);
 189             }
 190         }
 191     );
 192     (deref $p:expr, $constructor:ident) => (
 193         {
 194             let found = match ($p).token {
 195                 token::Interpolated(token::$constructor(_)) => {
 196                     Some(try!(($p).bump_and_get()))
 197                 }
 198                 _ => None
 199             };
 200             if let Some(token::Interpolated(token::$constructor(x))) = found {
 201                 return Ok((*x).clone());
 202             }
 203         }
 204     );
 205     (Some deref $p:expr, $constructor:ident) => (
 206         {
 207             let found = match ($p).token {
 208                 token::Interpolated(token::$constructor(_)) => {
 209                     Some(try!(($p).bump_and_get()))
 210                 }
 211                 _ => None
 212             };
 213             if let Some(token::Interpolated(token::$constructor(x))) = found {
 214                 return Ok(Some((*x).clone()));
 215             }
 216         }
 217     );
 218     (pair_empty $p:expr, $constructor:ident) => (
 219         {
 220             let found = match ($p).token {
 221                 token::Interpolated(token::$constructor(_)) => {
 222                     Some(try!(($p).bump_and_get()))
 223                 }
 224                 _ => None
 225             };
 226             if let Some(token::Interpolated(token::$constructor(x))) = found {
 227                 return Ok((Vec::new(), x));
 228             }
 229         }
 230     )
 231 }
 232
 233
 234 fn maybe_append(mut lhs: Vec<Attribute>, rhs: Option<Vec<Attribute>>)
 235                 -> Vec<Attribute> {
 236     if let Some(ref attrs) = rhs {
 237         lhs.extend(attrs.iter().cloned())
 238     }
 239     lhs
 240 }
 241
 242 /* ident is handled by common.rs */
 243
 244 pub struct Parser<'a> {
 245     pub sess: &'a ParseSess,
 246     /// the current token:
 247     pub token: token::Token,
 248     /// the span of the current token:
 249     pub span: Span,
 250     /// the span of the prior token:
 251     pub last_span: Span,
 252     pub cfg: CrateConfig,
 253     /// the previous token or None (only stashed sometimes).
 254     pub last_token: Option<Box<token::Token>>,
 255     pub buffer: [TokenAndSpan; 4],
 256     pub buffer_start: isize,
 257     pub buffer_end: isize,
 258     pub tokens_consumed: usize,
 259     pub restrictions: Restrictions,
 260     pub quote_depth: usize, // not (yet) related to the quasiquoter
 261     pub reader: Box<Reader+'a>,
 262     pub interner: Rc<token::IdentInterner>,
 263     /// The set of seen errors about obsolete syntax. Used to suppress
 264     /// extra detail when the same error is seen twice
 265     pub obsolete_set: HashSet<ObsoleteSyntax>,
 266     /// Used to determine the path to externally loaded source files
 267     pub mod_path_stack: Vec<InternedString>,
 268     /// Stack of spans of open delimiters. Used for error message.
 269     pub open_braces: Vec<Span>,
 270     /// Flag if this parser "owns" the directory that it is currently parsing
 271     /// in. This will affect how nested files are looked up.
 272     pub owns_directory: bool,
 273     /// Name of the root module this parser originated from. If `None`, then the
 274     /// name is not known. This does not change while the parser is descending
 275     /// into modules, and sub-parsers have new values for this name.
 276     pub root_module_name: Option<String>,
 277     pub expected_tokens: Vec<TokenType>,
 278 }
 279
 280 #[derive(PartialEq, Eq, Clone)]
 281 pub enum TokenType {
 282     Token(token::Token),
 283     Keyword(keywords::Keyword),
 284     Operator,
 285 }
 286
 287 impl TokenType {
 288     fn to_string(&self) -> String {
 289         match *self {
 290             TokenType::Token(ref t) => format!("`{}`", Parser::token_to_string(t)),
 291             TokenType::Operator => "an operator".to_string(),
 292             TokenType::Keyword(kw) => format!("`{}`", kw.to_name()),
 293         }
 294     }
 295 }
 296
 297 fn is_plain_ident_or_underscore(t: &token::Token) -> bool {
 298     t.is_plain_ident() || *t == token::Underscore
 299 }
 300
 301 /// Information about the path to a module.
 302 pub struct ModulePath {
 303     pub name: String,
 304     pub path_exists: bool,
 305     pub result: Result<ModulePathSuccess, ModulePathError>,
 306 }
 307
 308 pub struct ModulePathSuccess {
 309     pub path: ::std::path::PathBuf,
 310     pub owns_directory: bool,
 311 }
 312
 313 pub struct ModulePathError {
 314     pub err_msg: String,
 315     pub help_msg: String,
 316 }
 317
 318
 319 impl<'a> Parser<'a> {
 320     pub fn new(sess: &'a ParseSess,
 321                cfg: ast::CrateConfig,
 322                mut rdr: Box<Reader+'a>)
 323                -> Parser<'a>
 324     {
 325         let tok0 = rdr.real_token();
 326         let span = tok0.sp;
 327         let placeholder = TokenAndSpan {
 328             tok: token::Underscore,
 329             sp: span,
 330         };
 331
 332         Parser {
 333             reader: rdr,
 334             interner: token::get_ident_interner(),
 335             sess: sess,
 336             cfg: cfg,
 337             token: tok0.tok,
 338             span: span,
 339             last_span: span,
 340             last_token: None,
 341             buffer: [
 342                 placeholder.clone(),
 343                 placeholder.clone(),
 344                 placeholder.clone(),
 345                 placeholder.clone(),
 346             ],
 347             buffer_start: 0,
 348             buffer_end: 0,
 349             tokens_consumed: 0,
 350             restrictions: Restrictions::empty(),
 351             quote_depth: 0,
 352             obsolete_set: HashSet::new(),
 353             mod_path_stack: Vec::new(),
 354             open_braces: Vec::new(),
 355             owns_directory: true,
 356             root_module_name: None,
 357             expected_tokens: Vec::new(),
 358         }
 359     }
 360
 361     // Panicing fns (for now!)
 362     // This is so that the quote_*!() syntax extensions
 363     pub fn parse_expr(&mut self) -> P<Expr> {
 364         panictry!(self.parse_expr_nopanic())
 365     }
 366
 367     pub fn parse_item(&mut self) -> Option<P<Item>> {
 368         panictry!(self.parse_item_nopanic())
 369     }
 370
 371     pub fn parse_pat(&mut self) -> P<Pat> {
 372         panictry!(self.parse_pat_nopanic())
 373     }
 374
 375     pub fn parse_arm(&mut self) -> Arm {
 376         panictry!(self.parse_arm_nopanic())
 377     }
 378
 379     pub fn parse_ty(&mut self) -> P<Ty> {
 380         panictry!(self.parse_ty_nopanic())
 381     }
 382
 383     pub fn parse_stmt(&mut self) -> Option<P<Stmt>> {
 384         panictry!(self.parse_stmt_nopanic())
 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(slice::ref_slice(t), &[])
 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 = 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_nopanic());
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_nopanic());
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_nopanic())))
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_nopanic());
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_nopanic(&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_nopanic());
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, MacInvocTT(path, tts, 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_nopanic());
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         let pat = if require_name || self.is_named_argument() {
1450             debug!("parse_arg_general parse_pat (require_name:{})",
1451                    require_name);
1452             let pat = try!(self.parse_pat_nopanic());
1453
1454             try!(self.expect(&token::Colon));
1455             pat
1456         } else {
1457             debug!("parse_arg_general ident_to_pat");
1458             ast_util::ident_to_pat(ast::DUMMY_NODE_ID,
1459                                    self.last_span,
1460                                    special_idents::invalid)
1461         };
1462
1463         let t = try!(self.parse_ty_sum());
1464
1465         Ok(Arg {
1466             ty: t,
1467             pat: pat,
1468             id: ast::DUMMY_NODE_ID,
1469         })
1470     }
1471
1472     /// Parse a single function argument
1473     pub fn parse_arg(&mut self) -> PResult<Arg> {
1474         self.parse_arg_general(true)
1475     }
1476
1477     /// Parse an argument in a lambda header e.g. |arg, arg|
1478     pub fn parse_fn_block_arg(&mut self) -> PResult<Arg> {
1479         let pat = try!(self.parse_pat_nopanic());
1480         let t = if try!(self.eat(&token::Colon) ){
1481             try!(self.parse_ty_sum())
1482         } else {
1483             P(Ty {
1484                 id: ast::DUMMY_NODE_ID,
1485                 node: TyInfer,
1486                 span: mk_sp(self.span.lo, self.span.hi),
1487             })
1488         };
1489         Ok(Arg {
1490             ty: t,
1491             pat: pat,
1492             id: ast::DUMMY_NODE_ID
1493         })
1494     }
1495
1496     pub fn maybe_parse_fixed_length_of_vec(&mut self) -> PResult<Option<P<ast::Expr>>> {
1497         if self.check(&token::Semi) {
1498             try!(self.bump());
1499             Ok(Some(try!(self.parse_expr_nopanic())))
1500         } else {
1501             Ok(None)
1502         }
1503     }
1504
1505     /// Matches token_lit = LIT_INTEGER | ...
1506     pub fn lit_from_token(&self, tok: &token::Token) -> PResult<Lit_> {
1507         match *tok {
1508             token::Interpolated(token::NtExpr(ref v)) => {
1509                 match v.node {
1510                     ExprLit(ref lit) => { Ok(lit.node.clone()) }
1511                     _ => { return Err(self.unexpected_last(tok)); }
1512                 }
1513             }
1514             token::Literal(lit, suf) => {
1515                 let (suffix_illegal, out) = match lit {
1516                     token::Byte(i) => (true, LitByte(parse::byte_lit(&i.as_str()).0)),
1517                     token::Char(i) => (true, LitChar(parse::char_lit(&i.as_str()).0)),
1518
1519                     // there are some valid suffixes for integer and
1520                     // float literals, so all the handling is done
1521                     // internally.
1522                     token::Integer(s) => {
1523                         (false, parse::integer_lit(&s.as_str(),
1524                                                    suf.as_ref().map(|s| s.as_str()),
1525                                                    &self.sess.span_diagnostic,
1526                                                    self.last_span))
1527                     }
1528                     token::Float(s) => {
1529                         (false, parse::float_lit(&s.as_str(),
1530                                                  suf.as_ref().map(|s| s.as_str()),
1531                                                   &self.sess.span_diagnostic,
1532                                                  self.last_span))
1533                     }
1534
1535                     token::Str_(s) => {
1536                         (true,
1537                          LitStr(token::intern_and_get_ident(&parse::str_lit(&s.as_str())),
1538                                 ast::CookedStr))
1539                     }
1540                     token::StrRaw(s, n) => {
1541                         (true,
1542                          LitStr(
1543                             token::intern_and_get_ident(&parse::raw_str_lit(&s.as_str())),
1544                             ast::RawStr(n)))
1545                     }
1546                     token::ByteStr(i) =>
1547                         (true, LitByteStr(parse::byte_str_lit(&i.as_str()))),
1548                     token::ByteStrRaw(i, _) =>
1549                         (true,
1550                          LitByteStr(Rc::new(i.to_string().into_bytes()))),
1551                 };
1552
1553                 if suffix_illegal {
1554                     let sp = self.last_span;
1555                     self.expect_no_suffix(sp, &*format!("{} literal", lit.short_name()), suf)
1556                 }
1557
1558                 Ok(out)
1559             }
1560             _ => { return Err(self.unexpected_last(tok)); }
1561         }
1562     }
1563
1564     /// Matches lit = true | false | token_lit
1565     pub fn parse_lit(&mut self) -> PResult<Lit> {
1566         let lo = self.span.lo;
1567         let lit = if try!(self.eat_keyword(keywords::True) ){
1568             LitBool(true)
1569         } else if try!(self.eat_keyword(keywords::False) ){
1570             LitBool(false)
1571         } else {
1572             let token = try!(self.bump_and_get());
1573             let lit = try!(self.lit_from_token(&token));
1574             lit
1575         };
1576         Ok(codemap::Spanned { node: lit, span: mk_sp(lo, self.last_span.hi) })
1577     }
1578
1579     /// matches '-' lit | lit
1580     pub fn parse_literal_maybe_minus(&mut self) -> PResult<P<Expr>> {
1581         let minus_lo = self.span.lo;
1582         let minus_present = try!(self.eat(&token::BinOp(token::Minus)));
1583
1584         let lo = self.span.lo;
1585         let literal = P(try!(self.parse_lit()));
1586         let hi = self.span.hi;
1587         let expr = self.mk_expr(lo, hi, ExprLit(literal));
1588
1589         if minus_present {
1590             let minus_hi = self.span.hi;
1591             let unary = self.mk_unary(UnNeg, expr);
1592             Ok(self.mk_expr(minus_lo, minus_hi, unary))
1593         } else {
1594             Ok(expr)
1595         }
1596     }
1597
1598     // QUALIFIED PATH `<TYPE [as TRAIT_REF]>::IDENT[::<PARAMS>]`
1599     // Assumes that the leading `<` has been parsed already.
1600     pub fn parse_qualified_path(&mut self, mode: PathParsingMode)
1601                                 -> PResult<(QSelf, ast::Path)> {
1602         let span = self.last_span;
1603         let self_type = try!(self.parse_ty_sum());
1604         let mut path = if try!(self.eat_keyword(keywords::As)) {
1605             try!(self.parse_path(LifetimeAndTypesWithoutColons))
1606         } else {
1607             ast::Path {
1608                 span: span,
1609                 global: false,
1610                 segments: vec![]
1611             }
1612         };
1613
1614         let qself = QSelf {
1615             ty: self_type,
1616             position: path.segments.len()
1617         };
1618
1619         try!(self.expect(&token::Gt));
1620         try!(self.expect(&token::ModSep));
1621
1622         let segments = match mode {
1623             LifetimeAndTypesWithoutColons => {
1624                 try!(self.parse_path_segments_without_colons())
1625             }
1626             LifetimeAndTypesWithColons => {
1627                 try!(self.parse_path_segments_with_colons())
1628             }
1629             NoTypesAllowed => {
1630                 try!(self.parse_path_segments_without_types())
1631             }
1632         };
1633         path.segments.extend(segments);
1634
1635         path.span.hi = self.last_span.hi;
1636
1637         Ok((qself, path))
1638     }
1639
1640     /// Parses a path and optional type parameter bounds, depending on the
1641     /// mode. The `mode` parameter determines whether lifetimes, types, and/or
1642     /// bounds are permitted and whether `::` must precede type parameter
1643     /// groups.
1644     pub fn parse_path(&mut self, mode: PathParsingMode) -> PResult<ast::Path> {
1645         // Check for a whole path...
1646         let found = match self.token {
1647             token::Interpolated(token::NtPath(_)) => Some(try!(self.bump_and_get())),
1648             _ => None,
1649         };
1650         if let Some(token::Interpolated(token::NtPath(path))) = found {
1651             return Ok(*path);
1652         }
1653
1654         let lo = self.span.lo;
1655         let is_global = try!(self.eat(&token::ModSep));
1656
1657         // Parse any number of segments and bound sets. A segment is an
1658         // identifier followed by an optional lifetime and a set of types.
1659         // A bound set is a set of type parameter bounds.
1660         let segments = match mode {
1661             LifetimeAndTypesWithoutColons => {
1662                 try!(self.parse_path_segments_without_colons())
1663             }
1664             LifetimeAndTypesWithColons => {
1665                 try!(self.parse_path_segments_with_colons())
1666             }
1667             NoTypesAllowed => {
1668                 try!(self.parse_path_segments_without_types())
1669             }
1670         };
1671
1672         // Assemble the span.
1673         let span = mk_sp(lo, self.last_span.hi);
1674
1675         // Assemble the result.
1676         Ok(ast::Path {
1677             span: span,
1678             global: is_global,
1679             segments: segments,
1680         })
1681     }
1682
1683     /// Examples:
1684     /// - `a::b<T,U>::c<V,W>`
1685     /// - `a::b<T,U>::c(V) -> W`
1686     /// - `a::b<T,U>::c(V)`
1687     pub fn parse_path_segments_without_colons(&mut self) -> PResult<Vec<ast::PathSegment>> {
1688         let mut segments = Vec::new();
1689         loop {
1690             // First, parse an identifier.
1691             let identifier = try!(self.parse_ident_or_self_type());
1692
1693             // Parse types, optionally.
1694             let parameters = if try!(self.eat_lt() ){
1695                 let (lifetimes, types, bindings) = try!(self.parse_generic_values_after_lt());
1696
1697                 ast::AngleBracketedParameters(ast::AngleBracketedParameterData {
1698                     lifetimes: lifetimes,
1699                     types: OwnedSlice::from_vec(types),
1700                     bindings: OwnedSlice::from_vec(bindings),
1701                 })
1702             } else if try!(self.eat(&token::OpenDelim(token::Paren)) ){
1703                 let lo = self.last_span.lo;
1704
1705                 let inputs = try!(self.parse_seq_to_end(
1706                     &token::CloseDelim(token::Paren),
1707                     seq_sep_trailing_allowed(token::Comma),
1708                     |p| p.parse_ty_sum()));
1709
1710                 let output_ty = if try!(self.eat(&token::RArrow) ){
1711                     Some(try!(self.parse_ty_nopanic()))
1712                 } else {
1713                     None
1714                 };
1715
1716                 let hi = self.last_span.hi;
1717
1718                 ast::ParenthesizedParameters(ast::ParenthesizedParameterData {
1719                     span: mk_sp(lo, hi),
1720                     inputs: inputs,
1721                     output: output_ty,
1722                 })
1723             } else {
1724                 ast::PathParameters::none()
1725             };
1726
1727             // Assemble and push the result.
1728             segments.push(ast::PathSegment { identifier: identifier,
1729                                              parameters: parameters });
1730
1731             // Continue only if we see a `::`
1732             if !try!(self.eat(&token::ModSep) ){
1733                 return Ok(segments);
1734             }
1735         }
1736     }
1737
1738     /// Examples:
1739     /// - `a::b::<T,U>::c`
1740     pub fn parse_path_segments_with_colons(&mut self) -> PResult<Vec<ast::PathSegment>> {
1741         let mut segments = Vec::new();
1742         loop {
1743             // First, parse an identifier.
1744             let identifier = try!(self.parse_ident_or_self_type());
1745
1746             // If we do not see a `::`, stop.
1747             if !try!(self.eat(&token::ModSep) ){
1748                 segments.push(ast::PathSegment {
1749                     identifier: identifier,
1750                     parameters: ast::PathParameters::none()
1751                 });
1752                 return Ok(segments);
1753             }
1754
1755             // Check for a type segment.
1756             if try!(self.eat_lt() ){
1757                 // Consumed `a::b::<`, go look for types
1758                 let (lifetimes, types, bindings) = try!(self.parse_generic_values_after_lt());
1759                 segments.push(ast::PathSegment {
1760                     identifier: identifier,
1761                     parameters: ast::AngleBracketedParameters(ast::AngleBracketedParameterData {
1762                         lifetimes: lifetimes,
1763                         types: OwnedSlice::from_vec(types),
1764                         bindings: OwnedSlice::from_vec(bindings),
1765                     }),
1766                 });
1767
1768                 // Consumed `a::b::<T,U>`, check for `::` before proceeding
1769                 if !try!(self.eat(&token::ModSep) ){
1770                     return Ok(segments);
1771                 }
1772             } else {
1773                 // Consumed `a::`, go look for `b`
1774                 segments.push(ast::PathSegment {
1775                     identifier: identifier,
1776                     parameters: ast::PathParameters::none(),
1777                 });
1778             }
1779         }
1780     }
1781
1782
1783     /// Examples:
1784     /// - `a::b::c`
1785     pub fn parse_path_segments_without_types(&mut self) -> PResult<Vec<ast::PathSegment>> {
1786         let mut segments = Vec::new();
1787         loop {
1788             // First, parse an identifier.
1789             let identifier = try!(self.parse_ident_or_self_type());
1790
1791             // Assemble and push the result.
1792             segments.push(ast::PathSegment {
1793                 identifier: identifier,
1794                 parameters: ast::PathParameters::none()
1795             });
1796
1797             // If we do not see a `::`, stop.
1798             if !try!(self.eat(&token::ModSep) ){
1799                 return Ok(segments);
1800             }
1801         }
1802     }
1803
1804     /// parses 0 or 1 lifetime
1805     pub fn parse_opt_lifetime(&mut self) -> PResult<Option<ast::Lifetime>> {
1806         match self.token {
1807             token::Lifetime(..) => {
1808                 Ok(Some(try!(self.parse_lifetime())))
1809             }
1810             _ => {
1811                 Ok(None)
1812             }
1813         }
1814     }
1815
1816     /// Parses a single lifetime
1817     /// Matches lifetime = LIFETIME
1818     pub fn parse_lifetime(&mut self) -> PResult<ast::Lifetime> {
1819         match self.token {
1820             token::Lifetime(i) => {
1821                 let span = self.span;
1822                 try!(self.bump());
1823                 return Ok(ast::Lifetime {
1824                     id: ast::DUMMY_NODE_ID,
1825                     span: span,
1826                     name: i.name
1827                 });
1828             }
1829             _ => {
1830                 return Err(self.fatal(&format!("expected a lifetime name")));
1831             }
1832         }
1833     }
1834
1835     /// Parses `lifetime_defs = [ lifetime_defs { ',' lifetime_defs } ]` where `lifetime_def  =
1836     /// lifetime [':' lifetimes]`
1837     pub fn parse_lifetime_defs(&mut self) -> PResult<Vec<ast::LifetimeDef>> {
1838
1839         let mut res = Vec::new();
1840         loop {
1841             match self.token {
1842                 token::Lifetime(_) => {
1843                     let lifetime = try!(self.parse_lifetime());
1844                     let bounds =
1845                         if try!(self.eat(&token::Colon) ){
1846                             try!(self.parse_lifetimes(token::BinOp(token::Plus)))
1847                         } else {
1848                             Vec::new()
1849                         };
1850                     res.push(ast::LifetimeDef { lifetime: lifetime,
1851                                                 bounds: bounds });
1852                 }
1853
1854                 _ => {
1855                     return Ok(res);
1856                 }
1857             }
1858
1859             match self.token {
1860                 token::Comma => { try!(self.bump());}
1861                 token::Gt => { return Ok(res); }
1862                 token::BinOp(token::Shr) => { return Ok(res); }
1863                 _ => {
1864                     let this_token_str = self.this_token_to_string();
1865                     let msg = format!("expected `,` or `>` after lifetime \
1866                                       name, found `{}`",
1867                                       this_token_str);
1868                     return Err(self.fatal(&msg[..]));
1869                 }
1870             }
1871         }
1872     }
1873
1874     /// matches lifetimes = ( lifetime ) | ( lifetime , lifetimes ) actually, it matches the empty
1875     /// one too, but putting that in there messes up the grammar....
1876     ///
1877     /// Parses zero or more comma separated lifetimes. Expects each lifetime to be followed by
1878     /// either a comma or `>`.  Used when parsing type parameter lists, where we expect something
1879     /// like `<'a, 'b, T>`.
1880     pub fn parse_lifetimes(&mut self, sep: token::Token) -> PResult<Vec<ast::Lifetime>> {
1881
1882         let mut res = Vec::new();
1883         loop {
1884             match self.token {
1885                 token::Lifetime(_) => {
1886                     res.push(try!(self.parse_lifetime()));
1887                 }
1888                 _ => {
1889                     return Ok(res);
1890                 }
1891             }
1892
1893             if self.token != sep {
1894                 return Ok(res);
1895             }
1896
1897             try!(self.bump());
1898         }
1899     }
1900
1901     /// Parse mutability declaration (mut/const/imm)
1902     pub fn parse_mutability(&mut self) -> PResult<Mutability> {
1903         if try!(self.eat_keyword(keywords::Mut) ){
1904             Ok(MutMutable)
1905         } else {
1906             Ok(MutImmutable)
1907         }
1908     }
1909
1910     /// Parse ident COLON expr
1911     pub fn parse_field(&mut self) -> PResult<Field> {
1912         let lo = self.span.lo;
1913         let i = try!(self.parse_ident());
1914         let hi = self.last_span.hi;
1915         try!(self.expect(&token::Colon));
1916         let e = try!(self.parse_expr_nopanic());
1917         Ok(ast::Field {
1918             ident: spanned(lo, hi, i),
1919             span: mk_sp(lo, e.span.hi),
1920             expr: e,
1921         })
1922     }
1923
1924     pub fn mk_expr(&mut self, lo: BytePos, hi: BytePos, node: Expr_) -> P<Expr> {
1925         P(Expr {
1926             id: ast::DUMMY_NODE_ID,
1927             node: node,
1928             span: mk_sp(lo, hi),
1929         })
1930     }
1931
1932     pub fn mk_unary(&mut self, unop: ast::UnOp, expr: P<Expr>) -> ast::Expr_ {
1933         ExprUnary(unop, expr)
1934     }
1935
1936     pub fn mk_binary(&mut self, binop: ast::BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ast::Expr_ {
1937         ExprBinary(binop, lhs, rhs)
1938     }
1939
1940     pub fn mk_call(&mut self, f: P<Expr>, args: Vec<P<Expr>>) -> ast::Expr_ {
1941         ExprCall(f, args)
1942     }
1943
1944     fn mk_method_call(&mut self,
1945                       ident: ast::SpannedIdent,
1946                       tps: Vec<P<Ty>>,
1947                       args: Vec<P<Expr>>)
1948                       -> ast::Expr_ {
1949         ExprMethodCall(ident, tps, args)
1950     }
1951
1952     pub fn mk_index(&mut self, expr: P<Expr>, idx: P<Expr>) -> ast::Expr_ {
1953         ExprIndex(expr, idx)
1954     }
1955
1956     pub fn mk_range(&mut self,
1957                     start: Option<P<Expr>>,
1958                     end: Option<P<Expr>>)
1959                     -> ast::Expr_ {
1960         ExprRange(start, end)
1961     }
1962
1963     pub fn mk_field(&mut self, expr: P<Expr>, ident: ast::SpannedIdent) -> ast::Expr_ {
1964         ExprField(expr, ident)
1965     }
1966
1967     pub fn mk_tup_field(&mut self, expr: P<Expr>, idx: codemap::Spanned<usize>) -> ast::Expr_ {
1968         ExprTupField(expr, idx)
1969     }
1970
1971     pub fn mk_assign_op(&mut self, binop: ast::BinOp,
1972                         lhs: P<Expr>, rhs: P<Expr>) -> ast::Expr_ {
1973         ExprAssignOp(binop, lhs, rhs)
1974     }
1975
1976     pub fn mk_mac_expr(&mut self, lo: BytePos, hi: BytePos, m: Mac_) -> P<Expr> {
1977         P(Expr {
1978             id: ast::DUMMY_NODE_ID,
1979             node: ExprMac(codemap::Spanned {node: m, span: mk_sp(lo, hi)}),
1980             span: mk_sp(lo, hi),
1981         })
1982     }
1983
1984     pub fn mk_lit_u32(&mut self, i: u32) -> P<Expr> {
1985         let span = &self.span;
1986         let lv_lit = P(codemap::Spanned {
1987             node: LitInt(i as u64, ast::UnsignedIntLit(TyU32)),
1988             span: *span
1989         });
1990
1991         P(Expr {
1992             id: ast::DUMMY_NODE_ID,
1993             node: ExprLit(lv_lit),
1994             span: *span,
1995         })
1996     }
1997
1998     fn expect_open_delim(&mut self) -> PResult<token::DelimToken> {
1999         self.expected_tokens.push(TokenType::Token(token::Gt));
2000         match self.token {
2001             token::OpenDelim(delim) => {
2002                 try!(self.bump());
2003                 Ok(delim)
2004             },
2005             _ => Err(self.fatal("expected open delimiter")),
2006         }
2007     }
2008
2009     /// At the bottom (top?) of the precedence hierarchy,
2010     /// parse things like parenthesized exprs,
2011     /// macros, return, etc.
2012     pub fn parse_bottom_expr(&mut self) -> PResult<P<Expr>> {
2013         maybe_whole_expr!(self);
2014
2015         let lo = self.span.lo;
2016         let mut hi = self.span.hi;
2017
2018         let ex: Expr_;
2019
2020         // Note: when adding new syntax here, don't forget to adjust Token::can_begin_expr().
2021         match self.token {
2022             token::OpenDelim(token::Paren) => {
2023                 try!(self.bump());
2024
2025                 // (e) is parenthesized e
2026                 // (e,) is a tuple with only one field, e
2027                 let mut es = vec![];
2028                 let mut trailing_comma = false;
2029                 while self.token != token::CloseDelim(token::Paren) {
2030                     es.push(try!(self.parse_expr_nopanic()));
2031                     try!(self.commit_expr(&**es.last().unwrap(), &[],
2032                                      &[token::Comma, token::CloseDelim(token::Paren)]));
2033                     if self.check(&token::Comma) {
2034                         trailing_comma = true;
2035
2036                         try!(self.bump());
2037                     } else {
2038                         trailing_comma = false;
2039                         break;
2040                     }
2041                 }
2042                 try!(self.bump());
2043
2044                 hi = self.last_span.hi;
2045                 return if es.len() == 1 && !trailing_comma {
2046                     Ok(self.mk_expr(lo, hi, ExprParen(es.into_iter().nth(0).unwrap())))
2047                 } else {
2048                     Ok(self.mk_expr(lo, hi, ExprTup(es)))
2049                 }
2050             },
2051             token::OpenDelim(token::Brace) => {
2052                 return self.parse_block_expr(lo, DefaultBlock);
2053             },
2054             token::BinOp(token::Or) |  token::OrOr => {
2055                 let lo = self.span.lo;
2056                 return self.parse_lambda_expr(lo, CaptureByRef);
2057             },
2058             token::Ident(id @ ast::Ident {
2059                             name: token::SELF_KEYWORD_NAME,
2060                             ctxt: _
2061                          }, token::Plain) => {
2062                 try!(self.bump());
2063                 let path = ast_util::ident_to_path(mk_sp(lo, hi), id);
2064                 ex = ExprPath(None, path);
2065                 hi = self.last_span.hi;
2066             }
2067             token::OpenDelim(token::Bracket) => {
2068                 try!(self.bump());
2069
2070                 if self.check(&token::CloseDelim(token::Bracket)) {
2071                     // Empty vector.
2072                     try!(self.bump());
2073                     ex = ExprVec(Vec::new());
2074                 } else {
2075                     // Nonempty vector.
2076                     let first_expr = try!(self.parse_expr_nopanic());
2077                     if self.check(&token::Semi) {
2078                         // Repeating array syntax: [ 0; 512 ]
2079                         try!(self.bump());
2080                         let count = try!(self.parse_expr_nopanic());
2081                         try!(self.expect(&token::CloseDelim(token::Bracket)));
2082                         ex = ExprRepeat(first_expr, count);
2083                     } else if self.check(&token::Comma) {
2084                         // Vector with two or more elements.
2085                         try!(self.bump());
2086                         let remaining_exprs = try!(self.parse_seq_to_end(
2087                             &token::CloseDelim(token::Bracket),
2088                             seq_sep_trailing_allowed(token::Comma),
2089                             |p| Ok(try!(p.parse_expr_nopanic()))
2090                                 ));
2091                         let mut exprs = vec!(first_expr);
2092                         exprs.extend(remaining_exprs);
2093                         ex = ExprVec(exprs);
2094                     } else {
2095                         // Vector with one element.
2096                         try!(self.expect(&token::CloseDelim(token::Bracket)));
2097                         ex = ExprVec(vec!(first_expr));
2098                     }
2099                 }
2100                 hi = self.last_span.hi;
2101             }
2102             _ => {
2103                 if try!(self.eat_lt()){
2104                     let (qself, path) =
2105                         try!(self.parse_qualified_path(LifetimeAndTypesWithColons));
2106                     hi = path.span.hi;
2107                     return Ok(self.mk_expr(lo, hi, ExprPath(Some(qself), path)));
2108                 }
2109                 if try!(self.eat_keyword(keywords::Move) ){
2110                     let lo = self.last_span.lo;
2111                     return self.parse_lambda_expr(lo, CaptureByValue);
2112                 }
2113                 if try!(self.eat_keyword(keywords::If)) {
2114                     return self.parse_if_expr();
2115                 }
2116                 if try!(self.eat_keyword(keywords::For) ){
2117                     let lo = self.last_span.lo;
2118                     return self.parse_for_expr(None, lo);
2119                 }
2120                 if try!(self.eat_keyword(keywords::While) ){
2121                     let lo = self.last_span.lo;
2122                     return self.parse_while_expr(None, lo);
2123                 }
2124                 if self.token.is_lifetime() {
2125                     let lifetime = self.get_lifetime();
2126                     let lo = self.span.lo;
2127                     try!(self.bump());
2128                     try!(self.expect(&token::Colon));
2129                     if try!(self.eat_keyword(keywords::While) ){
2130                         return self.parse_while_expr(Some(lifetime), lo)
2131                     }
2132                     if try!(self.eat_keyword(keywords::For) ){
2133                         return self.parse_for_expr(Some(lifetime), lo)
2134                     }
2135                     if try!(self.eat_keyword(keywords::Loop) ){
2136                         return self.parse_loop_expr(Some(lifetime), lo)
2137                     }
2138                     return Err(self.fatal("expected `while`, `for`, or `loop` after a label"))
2139                 }
2140                 if try!(self.eat_keyword(keywords::Loop) ){
2141                     let lo = self.last_span.lo;
2142                     return self.parse_loop_expr(None, lo);
2143                 }
2144                 if try!(self.eat_keyword(keywords::Continue) ){
2145                     let ex = if self.token.is_lifetime() {
2146                         let ex = ExprAgain(Some(Spanned{
2147                             node: self.get_lifetime(),
2148                             span: self.span
2149                         }));
2150                         try!(self.bump());
2151                         ex
2152                     } else {
2153                         ExprAgain(None)
2154                     };
2155                     let hi = self.last_span.hi;
2156                     return Ok(self.mk_expr(lo, hi, ex));
2157                 }
2158                 if try!(self.eat_keyword(keywords::Match) ){
2159                     return self.parse_match_expr();
2160                 }
2161                 if try!(self.eat_keyword(keywords::Unsafe) ){
2162                     return self.parse_block_expr(
2163                         lo,
2164                         UnsafeBlock(ast::UserProvided));
2165                 }
2166                 if try!(self.eat_keyword(keywords::Return) ){
2167                     if self.token.can_begin_expr() {
2168                         let e = try!(self.parse_expr_nopanic());
2169                         hi = e.span.hi;
2170                         ex = ExprRet(Some(e));
2171                     } else {
2172                         ex = ExprRet(None);
2173                     }
2174                 } else if try!(self.eat_keyword(keywords::Break) ){
2175                     if self.token.is_lifetime() {
2176                         ex = ExprBreak(Some(Spanned {
2177                             node: self.get_lifetime(),
2178                             span: self.span
2179                         }));
2180                         try!(self.bump());
2181                     } else {
2182                         ex = ExprBreak(None);
2183                     }
2184                     hi = self.last_span.hi;
2185                 } else if self.check(&token::ModSep) ||
2186                         self.token.is_ident() &&
2187                         !self.check_keyword(keywords::True) &&
2188                         !self.check_keyword(keywords::False) {
2189                     let pth =
2190                         try!(self.parse_path(LifetimeAndTypesWithColons));
2191
2192                     // `!`, as an operator, is prefix, so we know this isn't that
2193                     if self.check(&token::Not) {
2194                         // MACRO INVOCATION expression
2195                         try!(self.bump());
2196
2197                         let delim = try!(self.expect_open_delim());
2198                         let tts = try!(self.parse_seq_to_end(
2199                             &token::CloseDelim(delim),
2200                             seq_sep_none(),
2201                             |p| p.parse_token_tree()));
2202                         let hi = self.last_span.hi;
2203
2204                         return Ok(self.mk_mac_expr(lo,
2205                                                    hi,
2206                                                    MacInvocTT(pth,
2207                                                               tts,
2208                                                               EMPTY_CTXT)));
2209                     }
2210                     if self.check(&token::OpenDelim(token::Brace)) {
2211                         // This is a struct literal, unless we're prohibited
2212                         // from parsing struct literals here.
2213                         let prohibited = self.restrictions.contains(
2214                             Restrictions::RESTRICTION_NO_STRUCT_LITERAL
2215                         );
2216                         if !prohibited {
2217                             // It's a struct literal.
2218                             try!(self.bump());
2219                             let mut fields = Vec::new();
2220                             let mut base = None;
2221
2222                             while self.token != token::CloseDelim(token::Brace) {
2223                                 if try!(self.eat(&token::DotDot) ){
2224                                     base = Some(try!(self.parse_expr_nopanic()));
2225                                     break;
2226                                 }
2227
2228                                 fields.push(try!(self.parse_field()));
2229                                 try!(self.commit_expr(&*fields.last().unwrap().expr,
2230                                                  &[token::Comma],
2231                                                  &[token::CloseDelim(token::Brace)]));
2232                             }
2233
2234                             if fields.is_empty() && base.is_none() {
2235                                 let last_span = self.last_span;
2236                                 self.span_err(last_span,
2237                                               "structure literal must either \
2238                                               have at least one field or use \
2239                                               structure update syntax");
2240                             }
2241
2242                             hi = self.span.hi;
2243                             try!(self.expect(&token::CloseDelim(token::Brace)));
2244                             ex = ExprStruct(pth, fields, base);
2245                             return Ok(self.mk_expr(lo, hi, ex));
2246                         }
2247                     }
2248
2249                     hi = pth.span.hi;
2250                     ex = ExprPath(None, pth);
2251                 } else {
2252                     // other literal expression
2253                     let lit = try!(self.parse_lit());
2254                     hi = lit.span.hi;
2255                     ex = ExprLit(P(lit));
2256                 }
2257             }
2258         }
2259
2260         return Ok(self.mk_expr(lo, hi, ex));
2261     }
2262
2263     /// Parse a block or unsafe block
2264     pub fn parse_block_expr(&mut self, lo: BytePos, blk_mode: BlockCheckMode)
2265                             -> PResult<P<Expr>> {
2266         try!(self.expect(&token::OpenDelim(token::Brace)));
2267         let blk = try!(self.parse_block_tail(lo, blk_mode));
2268         return Ok(self.mk_expr(blk.span.lo, blk.span.hi, ExprBlock(blk)));
2269     }
2270
2271     /// parse a.b or a(13) or a[4] or just a
2272     pub fn parse_dot_or_call_expr(&mut self) -> PResult<P<Expr>> {
2273         let b = try!(self.parse_bottom_expr());
2274         self.parse_dot_or_call_expr_with(b)
2275     }
2276
2277     pub fn parse_dot_or_call_expr_with(&mut self, e0: P<Expr>) -> PResult<P<Expr>> {
2278         let mut e = e0;
2279         let lo = e.span.lo;
2280         let mut hi;
2281         loop {
2282             // expr.f
2283             if try!(self.eat(&token::Dot) ){
2284                 match self.token {
2285                   token::Ident(i, _) => {
2286                     let dot = self.last_span.hi;
2287                     hi = self.span.hi;
2288                     try!(self.bump());
2289                     let (_, tys, bindings) = if try!(self.eat(&token::ModSep) ){
2290                         try!(self.expect_lt());
2291                         try!(self.parse_generic_values_after_lt())
2292                     } else {
2293                         (Vec::new(), Vec::new(), Vec::new())
2294                     };
2295
2296                     if !bindings.is_empty() {
2297                         let last_span = self.last_span;
2298                         self.span_err(last_span, "type bindings are only permitted on trait paths");
2299                     }
2300
2301                     // expr.f() method call
2302                     match self.token {
2303                         token::OpenDelim(token::Paren) => {
2304                             let mut es = try!(self.parse_unspanned_seq(
2305                                 &token::OpenDelim(token::Paren),
2306                                 &token::CloseDelim(token::Paren),
2307                                 seq_sep_trailing_allowed(token::Comma),
2308                                 |p| Ok(try!(p.parse_expr_nopanic()))
2309                             ));
2310                             hi = self.last_span.hi;
2311
2312                             es.insert(0, e);
2313                             let id = spanned(dot, hi, i);
2314                             let nd = self.mk_method_call(id, tys, es);
2315                             e = self.mk_expr(lo, hi, nd);
2316                         }
2317                         _ => {
2318                             if !tys.is_empty() {
2319                                 let last_span = self.last_span;
2320                                 self.span_err(last_span,
2321                                               "field expressions may not \
2322                                                have type parameters");
2323                             }
2324
2325                             let id = spanned(dot, hi, i);
2326                             let field = self.mk_field(e, id);
2327                             e = self.mk_expr(lo, hi, field);
2328                         }
2329                     }
2330                   }
2331                   token::Literal(token::Integer(n), suf) => {
2332                     let sp = self.span;
2333
2334                     // A tuple index may not have a suffix
2335                     self.expect_no_suffix(sp, "tuple index", suf);
2336
2337                     let dot = self.last_span.hi;
2338                     hi = self.span.hi;
2339                     try!(self.bump());
2340
2341                     let index = n.as_str().parse::<usize>().ok();
2342                     match index {
2343                         Some(n) => {
2344                             let id = spanned(dot, hi, n);
2345                             let field = self.mk_tup_field(e, id);
2346                             e = self.mk_expr(lo, hi, field);
2347                         }
2348                         None => {
2349                             let last_span = self.last_span;
2350                             self.span_err(last_span, "invalid tuple or tuple struct index");
2351                         }
2352                     }
2353                   }
2354                   token::Literal(token::Float(n), _suf) => {
2355                     try!(self.bump());
2356                     let last_span = self.last_span;
2357                     let fstr = n.as_str();
2358                     self.span_err(last_span,
2359                                   &format!("unexpected token: `{}`", n.as_str()));
2360                     if fstr.chars().all(|x| "0123456789.".contains(x)) {
2361                         let float = match fstr.parse::<f64>().ok() {
2362                             Some(f) => f,
2363                             None => continue,
2364                         };
2365                         self.fileline_help(last_span,
2366                             &format!("try parenthesizing the first index; e.g., `(foo.{}){}`",
2367                                     float.trunc() as usize,
2368                                     format!(".{}", fstr.splitn(2, ".").last().unwrap())));
2369                     }
2370                     self.abort_if_errors();
2371
2372                   }
2373                   _ => return Err(self.unexpected())
2374                 }
2375                 continue;
2376             }
2377             if self.expr_is_complete(&*e) { break; }
2378             match self.token {
2379               // expr(...)
2380               token::OpenDelim(token::Paren) => {
2381                 let es = try!(self.parse_unspanned_seq(
2382                     &token::OpenDelim(token::Paren),
2383                     &token::CloseDelim(token::Paren),
2384                     seq_sep_trailing_allowed(token::Comma),
2385                     |p| Ok(try!(p.parse_expr_nopanic()))
2386                 ));
2387                 hi = self.last_span.hi;
2388
2389                 let nd = self.mk_call(e, es);
2390                 e = self.mk_expr(lo, hi, nd);
2391               }
2392
2393               // expr[...]
2394               // Could be either an index expression or a slicing expression.
2395               token::OpenDelim(token::Bracket) => {
2396                 try!(self.bump());
2397                 let ix = try!(self.parse_expr_nopanic());
2398                 hi = self.span.hi;
2399                 try!(self.commit_expr_expecting(&*ix, token::CloseDelim(token::Bracket)));
2400                 let index = self.mk_index(e, ix);
2401                 e = self.mk_expr(lo, hi, index)
2402               }
2403               _ => return Ok(e)
2404             }
2405         }
2406         return Ok(e);
2407     }
2408
2409     // Parse unquoted tokens after a `$` in a token tree
2410     fn parse_unquoted(&mut self) -> PResult<TokenTree> {
2411         let mut sp = self.span;
2412         let (name, namep) = match self.token {
2413             token::Dollar => {
2414                 try!(self.bump());
2415
2416                 if self.token == token::OpenDelim(token::Paren) {
2417                     let Spanned { node: seq, span: seq_span } = try!(self.parse_seq(
2418                         &token::OpenDelim(token::Paren),
2419                         &token::CloseDelim(token::Paren),
2420                         seq_sep_none(),
2421                         |p| p.parse_token_tree()
2422                     ));
2423                     let (sep, repeat) = try!(self.parse_sep_and_kleene_op());
2424                     let name_num = macro_parser::count_names(&seq);
2425                     return Ok(TtSequence(mk_sp(sp.lo, seq_span.hi),
2426                                       Rc::new(SequenceRepetition {
2427                                           tts: seq,
2428                                           separator: sep,
2429                                           op: repeat,
2430                                           num_captures: name_num
2431                                       })));
2432                 } else if self.token.is_keyword_allow_following_colon(keywords::Crate) {
2433                     try!(self.bump());
2434                     return Ok(TtToken(sp, SpecialVarNt(SpecialMacroVar::CrateMacroVar)));
2435                 } else {
2436                     sp = mk_sp(sp.lo, self.span.hi);
2437                     let namep = match self.token { token::Ident(_, p) => p, _ => token::Plain };
2438                     let name = try!(self.parse_ident());
2439                     (name, namep)
2440                 }
2441             }
2442             token::SubstNt(name, namep) => {
2443                 try!(self.bump());
2444                 (name, namep)
2445             }
2446             _ => unreachable!()
2447         };
2448         // continue by trying to parse the `:ident` after `$name`
2449         if self.token == token::Colon && self.look_ahead(1, |t| t.is_ident() &&
2450                                                                 !t.is_strict_keyword() &&
2451                                                                 !t.is_reserved_keyword()) {
2452             try!(self.bump());
2453             sp = mk_sp(sp.lo, self.span.hi);
2454             let kindp = match self.token { token::Ident(_, p) => p, _ => token::Plain };
2455             let nt_kind = try!(self.parse_ident());
2456             Ok(TtToken(sp, MatchNt(name, nt_kind, namep, kindp)))
2457         } else {
2458             Ok(TtToken(sp, SubstNt(name, namep)))
2459         }
2460     }
2461
2462     pub fn check_unknown_macro_variable(&mut self) -> PResult<()> {
2463         if self.quote_depth == 0 {
2464             match self.token {
2465                 token::SubstNt(name, _) =>
2466                     return Err(self.fatal(&format!("unknown macro variable `{}`",
2467                                        name))),
2468                 _ => {}
2469             }
2470         }
2471         Ok(())
2472     }
2473
2474     /// Parse an optional separator followed by a Kleene-style
2475     /// repetition token (+ or *).
2476     pub fn parse_sep_and_kleene_op(&mut self) -> PResult<(Option<token::Token>, ast::KleeneOp)> {
2477         fn parse_kleene_op(parser: &mut Parser) -> PResult<Option<ast::KleeneOp>> {
2478             match parser.token {
2479                 token::BinOp(token::Star) => {
2480                     try!(parser.bump());
2481                     Ok(Some(ast::ZeroOrMore))
2482                 },
2483                 token::BinOp(token::Plus) => {
2484                     try!(parser.bump());
2485                     Ok(Some(ast::OneOrMore))
2486                 },
2487                 _ => Ok(None)
2488             }
2489         };
2490
2491         match try!(parse_kleene_op(self)) {
2492             Some(kleene_op) => return Ok((None, kleene_op)),
2493             None => {}
2494         }
2495
2496         let separator = try!(self.bump_and_get());
2497         match try!(parse_kleene_op(self)) {
2498             Some(zerok) => Ok((Some(separator), zerok)),
2499             None => return Err(self.fatal("expected `*` or `+`"))
2500         }
2501     }
2502
2503     /// parse a single token tree from the input.
2504     pub fn parse_token_tree(&mut self) -> PResult<TokenTree> {
2505         // FIXME #6994: currently, this is too eager. It
2506         // parses token trees but also identifies TtSequence's
2507         // and token::SubstNt's; it's too early to know yet
2508         // whether something will be a nonterminal or a seq
2509         // yet.
2510         maybe_whole!(deref self, NtTT);
2511
2512         // this is the fall-through for the 'match' below.
2513         // invariants: the current token is not a left-delimiter,
2514         // not an EOF, and not the desired right-delimiter (if
2515         // it were, parse_seq_to_before_end would have prevented
2516         // reaching this point.
2517         fn parse_non_delim_tt_tok(p: &mut Parser) -> PResult<TokenTree> {
2518             maybe_whole!(deref p, NtTT);
2519             match p.token {
2520                 token::CloseDelim(_) => {
2521                     // This is a conservative error: only report the last unclosed delimiter. The
2522                     // previous unclosed delimiters could actually be closed! The parser just hasn't
2523                     // gotten to them yet.
2524                     match p.open_braces.last() {
2525                         None => {}
2526                         Some(&sp) => p.span_note(sp, "unclosed delimiter"),
2527                     };
2528                     let token_str = p.this_token_to_string();
2529                     Err(p.fatal(&format!("incorrect close delimiter: `{}`",
2530                                     token_str)))
2531                 },
2532                 /* we ought to allow different depths of unquotation */
2533                 token::Dollar | token::SubstNt(..) if p.quote_depth > 0 => {
2534                     p.parse_unquoted()
2535                 }
2536                 _ => {
2537                     Ok(TtToken(p.span, try!(p.bump_and_get())))
2538                 }
2539             }
2540         }
2541
2542         match self.token {
2543             token::Eof => {
2544                 let open_braces = self.open_braces.clone();
2545                 for sp in &open_braces {
2546                     self.span_help(*sp, "did you mean to close this delimiter?");
2547                 }
2548                 // There shouldn't really be a span, but it's easier for the test runner
2549                 // if we give it one
2550                 return Err(self.fatal("this file contains an un-closed delimiter "));
2551             },
2552             token::OpenDelim(delim) => {
2553                 // The span for beginning of the delimited section
2554                 let pre_span = self.span;
2555
2556                 // Parse the open delimiter.
2557                 self.open_braces.push(self.span);
2558                 let open_span = self.span;
2559                 try!(self.bump());
2560
2561                 // Parse the token trees within the delimiters
2562                 let tts = try!(self.parse_seq_to_before_end(
2563                     &token::CloseDelim(delim),
2564                     seq_sep_none(),
2565                     |p| p.parse_token_tree()
2566                 ));
2567
2568                 // Parse the close delimiter.
2569                 let close_span = self.span;
2570                 try!(self.bump());
2571                 self.open_braces.pop().unwrap();
2572
2573                 // Expand to cover the entire delimited token tree
2574                 let span = Span { hi: close_span.hi, ..pre_span };
2575
2576                 Ok(TtDelimited(span, Rc::new(Delimited {
2577                     delim: delim,
2578                     open_span: open_span,
2579                     tts: tts,
2580                     close_span: close_span,
2581                 })))
2582             },
2583             _ => parse_non_delim_tt_tok(self),
2584         }
2585     }
2586
2587     // parse a stream of tokens into a list of TokenTree's,
2588     // up to EOF.
2589     pub fn parse_all_token_trees(&mut self) -> PResult<Vec<TokenTree>> {
2590         let mut tts = Vec::new();
2591         while self.token != token::Eof {
2592             tts.push(try!(self.parse_token_tree()));
2593         }
2594         Ok(tts)
2595     }
2596
2597     /// Parse a prefix-operator expr
2598     pub fn parse_prefix_expr(&mut self) -> PResult<P<Expr>> {
2599         let lo = self.span.lo;
2600         let hi;
2601
2602         // Note: when adding new unary operators, don't forget to adjust Token::can_begin_expr()
2603         let ex;
2604         match self.token {
2605           token::Not => {
2606             try!(self.bump());
2607             let e = try!(self.parse_prefix_expr());
2608             hi = e.span.hi;
2609             ex = self.mk_unary(UnNot, e);
2610           }
2611           token::BinOp(token::Minus) => {
2612             try!(self.bump());
2613             let e = try!(self.parse_prefix_expr());
2614             hi = e.span.hi;
2615             ex = self.mk_unary(UnNeg, e);
2616           }
2617           token::BinOp(token::Star) => {
2618             try!(self.bump());
2619             let e = try!(self.parse_prefix_expr());
2620             hi = e.span.hi;
2621             ex = self.mk_unary(UnDeref, e);
2622           }
2623           token::BinOp(token::And) | token::AndAnd => {
2624             try!(self.expect_and());
2625             let m = try!(self.parse_mutability());
2626             let e = try!(self.parse_prefix_expr());
2627             hi = e.span.hi;
2628             ex = ExprAddrOf(m, e);
2629           }
2630           token::Ident(_, _) => {
2631             if !self.check_keyword(keywords::Box) && !self.check_keyword(keywords::In) {
2632                 return self.parse_dot_or_call_expr();
2633             }
2634
2635             let lo = self.span.lo;
2636             let keyword_hi = self.span.hi;
2637
2638             let is_in = self.token.is_keyword(keywords::In);
2639             try!(self.bump());
2640
2641             if is_in {
2642               let place = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL));
2643               let blk = try!(self.parse_block());
2644               hi = blk.span.hi;
2645               let blk_expr = self.mk_expr(blk.span.lo, blk.span.hi, ExprBlock(blk));
2646               ex = ExprBox(Some(place), blk_expr);
2647               return Ok(self.mk_expr(lo, hi, ex));
2648             }
2649
2650             // FIXME (#22181) Remove `box (PLACE) EXPR` support
2651             // entirely after next release (enabling `(box (EXPR))`),
2652             // since it will be replaced by `in PLACE { EXPR }`, ...
2653             //
2654             // ... but for now: check for a place: `box(PLACE) EXPR`.
2655
2656             if try!(self.eat(&token::OpenDelim(token::Paren))) {
2657                 let box_span = mk_sp(lo, self.last_span.hi);
2658                 self.span_warn(box_span,
2659                     "deprecated syntax; use the `in` keyword now \
2660                            (e.g. change `box (<expr>) <expr>` to \
2661                                         `in <expr> { <expr> }`)");
2662
2663                 // Continue supporting `box () EXPR` (temporarily)
2664                 if !try!(self.eat(&token::CloseDelim(token::Paren))) {
2665                     let place = try!(self.parse_expr_nopanic());
2666                     try!(self.expect(&token::CloseDelim(token::Paren)));
2667                     // Give a suggestion to use `box()` when a parenthesised expression is used
2668                     if !self.token.can_begin_expr() {
2669                         let span = self.span;
2670                         let this_token_to_string = self.this_token_to_string();
2671                         self.span_err(span,
2672                                       &format!("expected expression, found `{}`",
2673                                               this_token_to_string));
2674
2675                         // Spanning just keyword avoids constructing
2676                         // printout of arg expression (which starts
2677                         // with parenthesis, as established above).
2678
2679                         let box_span = mk_sp(lo, keyword_hi);
2680                         self.span_suggestion(box_span,
2681                                              "try using `box ()` instead:",
2682                                              format!("box ()"));
2683                         self.abort_if_errors();
2684                     }
2685                     let subexpression = try!(self.parse_prefix_expr());
2686                     hi = subexpression.span.hi;
2687                     ex = ExprBox(Some(place), subexpression);
2688                     return Ok(self.mk_expr(lo, hi, ex));
2689                 }
2690             }
2691
2692             // Otherwise, we use the unique pointer default.
2693             let subexpression = try!(self.parse_prefix_expr());
2694             hi = subexpression.span.hi;
2695
2696             // FIXME (pnkfelix): After working out kinks with box
2697             // desugaring, should be `ExprBox(None, subexpression)`
2698             // instead.
2699             ex = self.mk_unary(UnUniq, subexpression);
2700           }
2701           _ => return self.parse_dot_or_call_expr()
2702         }
2703         return Ok(self.mk_expr(lo, hi, ex));
2704     }
2705
2706     /// Parse an expression of binops
2707     pub fn parse_binops(&mut self) -> PResult<P<Expr>> {
2708         let prefix_expr = try!(self.parse_prefix_expr());
2709         self.parse_more_binops(prefix_expr, 0)
2710     }
2711
2712     /// Parse an expression of binops of at least min_prec precedence
2713     pub fn parse_more_binops(&mut self, lhs: P<Expr>, min_prec: usize) -> PResult<P<Expr>> {
2714         if self.expr_is_complete(&*lhs) { return Ok(lhs); }
2715
2716         self.expected_tokens.push(TokenType::Operator);
2717
2718         let cur_op_span = self.span;
2719         let cur_opt = self.token.to_binop();
2720         match cur_opt {
2721             Some(cur_op) => {
2722                 if ast_util::is_comparison_binop(cur_op) {
2723                     self.check_no_chained_comparison(&*lhs, cur_op)
2724                 }
2725                 let cur_prec = operator_prec(cur_op);
2726                 if cur_prec >= min_prec {
2727                     try!(self.bump());
2728                     let expr = try!(self.parse_prefix_expr());
2729                     let rhs = try!(self.parse_more_binops(expr, cur_prec + 1));
2730                     let lhs_span = lhs.span;
2731                     let rhs_span = rhs.span;
2732                     let binary = self.mk_binary(codemap::respan(cur_op_span, cur_op), lhs, rhs);
2733                     let bin = self.mk_expr(lhs_span.lo, rhs_span.hi, binary);
2734                     self.parse_more_binops(bin, min_prec)
2735                 } else {
2736                     Ok(lhs)
2737                 }
2738             }
2739             None => {
2740                 if AS_PREC >= min_prec && try!(self.eat_keyword_noexpect(keywords::As) ){
2741                     let rhs = try!(self.parse_ty_nopanic());
2742                     let _as = self.mk_expr(lhs.span.lo,
2743                                            rhs.span.hi,
2744                                            ExprCast(lhs, rhs));
2745                     self.parse_more_binops(_as, min_prec)
2746                 } else {
2747                     Ok(lhs)
2748                 }
2749             }
2750         }
2751     }
2752
2753     /// Produce an error if comparison operators are chained (RFC #558).
2754     /// We only need to check lhs, not rhs, because all comparison ops
2755     /// have same precedence and are left-associative
2756     fn check_no_chained_comparison(&mut self, lhs: &Expr, outer_op: ast::BinOp_) {
2757         debug_assert!(ast_util::is_comparison_binop(outer_op));
2758         match lhs.node {
2759             ExprBinary(op, _, _) if ast_util::is_comparison_binop(op.node) => {
2760                 // respan to include both operators
2761                 let op_span = mk_sp(op.span.lo, self.span.hi);
2762                 self.span_err(op_span,
2763                     "chained comparison operators require parentheses");
2764                 if op.node == BiLt && outer_op == BiGt {
2765                     self.fileline_help(op_span,
2766                         "use `::<...>` instead of `<...>` if you meant to specify type arguments");
2767                 }
2768             }
2769             _ => {}
2770         }
2771     }
2772
2773     /// Parse an assignment expression....
2774     /// actually, this seems to be the main entry point for
2775     /// parsing an arbitrary expression.
2776     pub fn parse_assign_expr(&mut self) -> PResult<P<Expr>> {
2777         match self.token {
2778           token::DotDot => {
2779             // prefix-form of range notation '..expr'
2780             // This has the same precedence as assignment expressions
2781             // (much lower than other prefix expressions) to be consistent
2782             // with the postfix-form 'expr..'
2783             let lo = self.span.lo;
2784             let mut hi = self.span.hi;
2785             try!(self.bump());
2786             let opt_end = if self.is_at_start_of_range_notation_rhs() {
2787                 let end = try!(self.parse_binops());
2788                 hi = end.span.hi;
2789                 Some(end)
2790             } else {
2791                 None
2792             };
2793             let ex = self.mk_range(None, opt_end);
2794             Ok(self.mk_expr(lo, hi, ex))
2795           }
2796           _ => {
2797             let lhs = try!(self.parse_binops());
2798             self.parse_assign_expr_with(lhs)
2799           }
2800         }
2801     }
2802
2803     pub fn parse_assign_expr_with(&mut self, lhs: P<Expr>) -> PResult<P<Expr>> {
2804         let restrictions = self.restrictions & Restrictions::RESTRICTION_NO_STRUCT_LITERAL;
2805         let op_span = self.span;
2806         match self.token {
2807           token::Eq => {
2808               try!(self.bump());
2809               let rhs = try!(self.parse_expr_res(restrictions));
2810               Ok(self.mk_expr(lhs.span.lo, rhs.span.hi, ExprAssign(lhs, rhs)))
2811           }
2812           token::BinOpEq(op) => {
2813               try!(self.bump());
2814               let rhs = try!(self.parse_expr_res(restrictions));
2815               let aop = match op {
2816                   token::Plus =>    BiAdd,
2817                   token::Minus =>   BiSub,
2818                   token::Star =>    BiMul,
2819                   token::Slash =>   BiDiv,
2820                   token::Percent => BiRem,
2821                   token::Caret =>   BiBitXor,
2822                   token::And =>     BiBitAnd,
2823                   token::Or =>      BiBitOr,
2824                   token::Shl =>     BiShl,
2825                   token::Shr =>     BiShr
2826               };
2827               let rhs_span = rhs.span;
2828               let span = lhs.span;
2829               let assign_op = self.mk_assign_op(codemap::respan(op_span, aop), lhs, rhs);
2830               Ok(self.mk_expr(span.lo, rhs_span.hi, assign_op))
2831           }
2832           // A range expression, either `expr..expr` or `expr..`.
2833           token::DotDot => {
2834             let lo = lhs.span.lo;
2835             let mut hi = self.span.hi;
2836             try!(self.bump());
2837
2838             let opt_end = if self.is_at_start_of_range_notation_rhs() {
2839                 let end = try!(self.parse_binops());
2840                 hi = end.span.hi;
2841                 Some(end)
2842             } else {
2843                 None
2844             };
2845             let range = self.mk_range(Some(lhs), opt_end);
2846             return Ok(self.mk_expr(lo, hi, range));
2847           }
2848
2849           _ => {
2850               Ok(lhs)
2851           }
2852         }
2853     }
2854
2855     fn is_at_start_of_range_notation_rhs(&self) -> bool {
2856         if self.token.can_begin_expr() {
2857             // parse `for i in 1.. { }` as infinite loop, not as `for i in (1..{})`.
2858             if self.token == token::OpenDelim(token::Brace) {
2859                 return !self.restrictions.contains(Restrictions::RESTRICTION_NO_STRUCT_LITERAL);
2860             }
2861             true
2862         } else {
2863             false
2864         }
2865     }
2866
2867     /// Parse an 'if' or 'if let' expression ('if' token already eaten)
2868     pub fn parse_if_expr(&mut self) -> PResult<P<Expr>> {
2869         if self.check_keyword(keywords::Let) {
2870             return self.parse_if_let_expr();
2871         }
2872         let lo = self.last_span.lo;
2873         let cond = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL));
2874         let thn = try!(self.parse_block());
2875         let mut els: Option<P<Expr>> = None;
2876         let mut hi = thn.span.hi;
2877         if try!(self.eat_keyword(keywords::Else) ){
2878             let elexpr = try!(self.parse_else_expr());
2879             hi = elexpr.span.hi;
2880             els = Some(elexpr);
2881         }
2882         Ok(self.mk_expr(lo, hi, ExprIf(cond, thn, els)))
2883     }
2884
2885     /// Parse an 'if let' expression ('if' token already eaten)
2886     pub fn parse_if_let_expr(&mut self) -> PResult<P<Expr>> {
2887         let lo = self.last_span.lo;
2888         try!(self.expect_keyword(keywords::Let));
2889         let pat = try!(self.parse_pat_nopanic());
2890         try!(self.expect(&token::Eq));
2891         let expr = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL));
2892         let thn = try!(self.parse_block());
2893         let (hi, els) = if try!(self.eat_keyword(keywords::Else) ){
2894             let expr = try!(self.parse_else_expr());
2895             (expr.span.hi, Some(expr))
2896         } else {
2897             (thn.span.hi, None)
2898         };
2899         Ok(self.mk_expr(lo, hi, ExprIfLet(pat, expr, thn, els)))
2900     }
2901
2902     // `|args| expr`
2903     pub fn parse_lambda_expr(&mut self, lo: BytePos, capture_clause: CaptureClause)
2904                              -> PResult<P<Expr>>
2905     {
2906         let decl = try!(self.parse_fn_block_decl());
2907         let body = match decl.output {
2908             DefaultReturn(_) => {
2909                 // If no explicit return type is given, parse any
2910                 // expr and wrap it up in a dummy block:
2911                 let body_expr = try!(self.parse_expr_nopanic());
2912                 P(ast::Block {
2913                     id: ast::DUMMY_NODE_ID,
2914                     stmts: vec![],
2915                     span: body_expr.span,
2916                     expr: Some(body_expr),
2917                     rules: DefaultBlock,
2918                 })
2919             }
2920             _ => {
2921                 // If an explicit return type is given, require a
2922                 // block to appear (RFC 968).
2923                 try!(self.parse_block())
2924             }
2925         };
2926
2927         Ok(self.mk_expr(
2928             lo,
2929             body.span.hi,
2930             ExprClosure(capture_clause, decl, body)))
2931     }
2932
2933     pub fn parse_else_expr(&mut self) -> PResult<P<Expr>> {
2934         if try!(self.eat_keyword(keywords::If) ){
2935             return self.parse_if_expr();
2936         } else {
2937             let blk = try!(self.parse_block());
2938             return Ok(self.mk_expr(blk.span.lo, blk.span.hi, ExprBlock(blk)));
2939         }
2940     }
2941
2942     /// Parse a 'for' .. 'in' expression ('for' token already eaten)
2943     pub fn parse_for_expr(&mut self, opt_ident: Option<ast::Ident>,
2944                           span_lo: BytePos) -> PResult<P<Expr>> {
2945         // Parse: `for <src_pat> in <src_expr> <src_loop_block>`
2946
2947         let pat = try!(self.parse_pat_nopanic());
2948         try!(self.expect_keyword(keywords::In));
2949         let expr = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL));
2950         let loop_block = try!(self.parse_block());
2951         let hi = self.last_span.hi;
2952
2953         Ok(self.mk_expr(span_lo, hi, ExprForLoop(pat, expr, loop_block, opt_ident)))
2954     }
2955
2956     /// Parse a 'while' or 'while let' expression ('while' token already eaten)
2957     pub fn parse_while_expr(&mut self, opt_ident: Option<ast::Ident>,
2958                             span_lo: BytePos) -> PResult<P<Expr>> {
2959         if self.token.is_keyword(keywords::Let) {
2960             return self.parse_while_let_expr(opt_ident, span_lo);
2961         }
2962         let cond = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL));
2963         let body = try!(self.parse_block());
2964         let hi = body.span.hi;
2965         return Ok(self.mk_expr(span_lo, hi, ExprWhile(cond, body, opt_ident)));
2966     }
2967
2968     /// Parse a 'while let' expression ('while' token already eaten)
2969     pub fn parse_while_let_expr(&mut self, opt_ident: Option<ast::Ident>,
2970                                 span_lo: BytePos) -> PResult<P<Expr>> {
2971         try!(self.expect_keyword(keywords::Let));
2972         let pat = try!(self.parse_pat_nopanic());
2973         try!(self.expect(&token::Eq));
2974         let expr = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL));
2975         let body = try!(self.parse_block());
2976         let hi = body.span.hi;
2977         return Ok(self.mk_expr(span_lo, hi, ExprWhileLet(pat, expr, body, opt_ident)));
2978     }
2979
2980     pub fn parse_loop_expr(&mut self, opt_ident: Option<ast::Ident>,
2981                            span_lo: BytePos) -> PResult<P<Expr>> {
2982         let body = try!(self.parse_block());
2983         let hi = body.span.hi;
2984         Ok(self.mk_expr(span_lo, hi, ExprLoop(body, opt_ident)))
2985     }
2986
2987     fn parse_match_expr(&mut self) -> PResult<P<Expr>> {
2988         let lo = self.last_span.lo;
2989         let discriminant = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL));
2990         try!(self.commit_expr_expecting(&*discriminant, token::OpenDelim(token::Brace)));
2991         let mut arms: Vec<Arm> = Vec::new();
2992         while self.token != token::CloseDelim(token::Brace) {
2993             arms.push(try!(self.parse_arm_nopanic()));
2994         }
2995         let hi = self.span.hi;
2996         try!(self.bump());
2997         return Ok(self.mk_expr(lo, hi, ExprMatch(discriminant, arms, MatchSource::Normal)));
2998     }
2999
3000     pub fn parse_arm_nopanic(&mut self) -> PResult<Arm> {
3001         maybe_whole!(no_clone self, NtArm);
3002
3003         let attrs = self.parse_outer_attributes();
3004         let pats = try!(self.parse_pats());
3005         let mut guard = None;
3006         if try!(self.eat_keyword(keywords::If) ){
3007             guard = Some(try!(self.parse_expr_nopanic()));
3008         }
3009         try!(self.expect(&token::FatArrow));
3010         let expr = try!(self.parse_expr_res(Restrictions::RESTRICTION_STMT_EXPR));
3011
3012         let require_comma =
3013             !classify::expr_is_simple_block(&*expr)
3014             && self.token != token::CloseDelim(token::Brace);
3015
3016         if require_comma {
3017             try!(self.commit_expr(&*expr, &[token::Comma], &[token::CloseDelim(token::Brace)]));
3018         } else {
3019             try!(self.eat(&token::Comma));
3020         }
3021
3022         Ok(ast::Arm {
3023             attrs: attrs,
3024             pats: pats,
3025             guard: guard,
3026             body: expr,
3027         })
3028     }
3029
3030     /// Parse an expression
3031     pub fn parse_expr_nopanic(&mut self) -> PResult<P<Expr>> {
3032         self.parse_expr_res(Restrictions::empty())
3033     }
3034
3035     /// Parse an expression, subject to the given restrictions
3036     pub fn parse_expr_res(&mut self, r: Restrictions) -> PResult<P<Expr>> {
3037         let old = self.restrictions;
3038         self.restrictions = r;
3039         let e = try!(self.parse_assign_expr());
3040         self.restrictions = old;
3041         return Ok(e);
3042     }
3043
3044     /// Parse the RHS of a local variable declaration (e.g. '= 14;')
3045     fn parse_initializer(&mut self) -> PResult<Option<P<Expr>>> {
3046         if self.check(&token::Eq) {
3047             try!(self.bump());
3048             Ok(Some(try!(self.parse_expr_nopanic())))
3049         } else {
3050             Ok(None)
3051         }
3052     }
3053
3054     /// Parse patterns, separated by '|' s
3055     fn parse_pats(&mut self) -> PResult<Vec<P<Pat>>> {
3056         let mut pats = Vec::new();
3057         loop {
3058             pats.push(try!(self.parse_pat_nopanic()));
3059             if self.check(&token::BinOp(token::Or)) { try!(self.bump());}
3060             else { return Ok(pats); }
3061         };
3062     }
3063
3064     fn parse_pat_tuple_elements(&mut self) -> PResult<Vec<P<Pat>>> {
3065         let mut fields = vec![];
3066         if !self.check(&token::CloseDelim(token::Paren)) {
3067             fields.push(try!(self.parse_pat_nopanic()));
3068             if self.look_ahead(1, |t| *t != token::CloseDelim(token::Paren)) {
3069                 while try!(self.eat(&token::Comma)) &&
3070                       !self.check(&token::CloseDelim(token::Paren)) {
3071                     fields.push(try!(self.parse_pat_nopanic()));
3072                 }
3073             }
3074             if fields.len() == 1 {
3075                 try!(self.expect(&token::Comma));
3076             }
3077         }
3078         Ok(fields)
3079     }
3080
3081     fn parse_pat_vec_elements(
3082         &mut self,
3083     ) -> PResult<(Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>)> {
3084         let mut before = Vec::new();
3085         let mut slice = None;
3086         let mut after = Vec::new();
3087         let mut first = true;
3088         let mut before_slice = true;
3089
3090         while self.token != token::CloseDelim(token::Bracket) {
3091             if first {
3092                 first = false;
3093             } else {
3094                 try!(self.expect(&token::Comma));
3095
3096                 if self.token == token::CloseDelim(token::Bracket)
3097                         && (before_slice || !after.is_empty()) {
3098                     break
3099                 }
3100             }
3101
3102             if before_slice {
3103                 if self.check(&token::DotDot) {
3104                     try!(self.bump());
3105
3106                     if self.check(&token::Comma) ||
3107                             self.check(&token::CloseDelim(token::Bracket)) {
3108                         slice = Some(P(ast::Pat {
3109                             id: ast::DUMMY_NODE_ID,
3110                             node: PatWild(PatWildMulti),
3111                             span: self.span,
3112                         }));
3113                         before_slice = false;
3114                     }
3115                     continue
3116                 }
3117             }
3118
3119             let subpat = try!(self.parse_pat_nopanic());
3120             if before_slice && self.check(&token::DotDot) {
3121                 try!(self.bump());
3122                 slice = Some(subpat);
3123                 before_slice = false;
3124             } else if before_slice {
3125                 before.push(subpat);
3126             } else {
3127                 after.push(subpat);
3128             }
3129         }
3130
3131         Ok((before, slice, after))
3132     }
3133
3134     /// Parse the fields of a struct-like pattern
3135     fn parse_pat_fields(&mut self) -> PResult<(Vec<codemap::Spanned<ast::FieldPat>> , bool)> {
3136         let mut fields = Vec::new();
3137         let mut etc = false;
3138         let mut first = true;
3139         while self.token != token::CloseDelim(token::Brace) {
3140             if first {
3141                 first = false;
3142             } else {
3143                 try!(self.expect(&token::Comma));
3144                 // accept trailing commas
3145                 if self.check(&token::CloseDelim(token::Brace)) { break }
3146             }
3147
3148             let lo = self.span.lo;
3149             let hi;
3150
3151             if self.check(&token::DotDot) {
3152                 try!(self.bump());
3153                 if self.token != token::CloseDelim(token::Brace) {
3154                     let token_str = self.this_token_to_string();
3155                     return Err(self.fatal(&format!("expected `{}`, found `{}`", "}",
3156                                        token_str)))
3157                 }
3158                 etc = true;
3159                 break;
3160             }
3161
3162             // Check if a colon exists one ahead. This means we're parsing a fieldname.
3163             let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
3164                 // Parsing a pattern of the form "fieldname: pat"
3165                 let fieldname = try!(self.parse_ident());
3166                 try!(self.bump());
3167                 let pat = try!(self.parse_pat_nopanic());
3168                 hi = pat.span.hi;
3169                 (pat, fieldname, false)
3170             } else {
3171                 // Parsing a pattern of the form "(box) (ref) (mut) fieldname"
3172                 let is_box = try!(self.eat_keyword(keywords::Box));
3173                 let boxed_span_lo = self.span.lo;
3174                 let is_ref = try!(self.eat_keyword(keywords::Ref));
3175                 let is_mut = try!(self.eat_keyword(keywords::Mut));
3176                 let fieldname = try!(self.parse_ident());
3177                 hi = self.last_span.hi;
3178
3179                 let bind_type = match (is_ref, is_mut) {
3180                     (true, true) => BindByRef(MutMutable),
3181                     (true, false) => BindByRef(MutImmutable),
3182                     (false, true) => BindByValue(MutMutable),
3183                     (false, false) => BindByValue(MutImmutable),
3184                 };
3185                 let fieldpath = codemap::Spanned{span:self.last_span, node:fieldname};
3186                 let fieldpat = P(ast::Pat{
3187                     id: ast::DUMMY_NODE_ID,
3188                     node: PatIdent(bind_type, fieldpath, None),
3189                     span: mk_sp(boxed_span_lo, hi),
3190                 });
3191
3192                 let subpat = if is_box {
3193                     P(ast::Pat{
3194                         id: ast::DUMMY_NODE_ID,
3195                         node: PatBox(fieldpat),
3196                         span: mk_sp(lo, hi),
3197                     })
3198                 } else {
3199                     fieldpat
3200                 };
3201                 (subpat, fieldname, true)
3202             };
3203
3204             fields.push(codemap::Spanned { span: mk_sp(lo, hi),
3205                                            node: ast::FieldPat { ident: fieldname,
3206                                                                  pat: subpat,
3207                                                                  is_shorthand: is_shorthand }});
3208         }
3209         return Ok((fields, etc));
3210     }
3211
3212     fn parse_pat_range_end(&mut self) -> PResult<P<Expr>> {
3213         if self.is_path_start() {
3214             let lo = self.span.lo;
3215             let (qself, path) = if try!(self.eat_lt()) {
3216                 // Parse a qualified path
3217                 let (qself, path) =
3218                     try!(self.parse_qualified_path(NoTypesAllowed));
3219                 (Some(qself), path)
3220             } else {
3221                 // Parse an unqualified path
3222                 (None, try!(self.parse_path(LifetimeAndTypesWithColons)))
3223             };
3224             let hi = self.last_span.hi;
3225             Ok(self.mk_expr(lo, hi, ExprPath(qself, path)))
3226         } else {
3227             self.parse_literal_maybe_minus()
3228         }
3229     }
3230
3231     fn is_path_start(&self) -> bool {
3232         (self.token == token::Lt || self.token == token::ModSep
3233             || self.token.is_ident() || self.token.is_path())
3234             && !self.token.is_keyword(keywords::True) && !self.token.is_keyword(keywords::False)
3235     }
3236
3237     /// Parse a pattern.
3238     pub fn parse_pat_nopanic(&mut self) -> PResult<P<Pat>> {
3239         maybe_whole!(self, NtPat);
3240
3241         let lo = self.span.lo;
3242         let pat;
3243         match self.token {
3244           token::Underscore => {
3245             // Parse _
3246             try!(self.bump());
3247             pat = PatWild(PatWildSingle);
3248           }
3249           token::BinOp(token::And) | token::AndAnd => {
3250             // Parse &pat / &mut pat
3251             try!(self.expect_and());
3252             let mutbl = try!(self.parse_mutability());
3253             let subpat = try!(self.parse_pat_nopanic());
3254             pat = PatRegion(subpat, mutbl);
3255           }
3256           token::OpenDelim(token::Paren) => {
3257             // Parse (pat,pat,pat,...) as tuple pattern
3258             try!(self.bump());
3259             let fields = try!(self.parse_pat_tuple_elements());
3260             try!(self.expect(&token::CloseDelim(token::Paren)));
3261             pat = PatTup(fields);
3262           }
3263           token::OpenDelim(token::Bracket) => {
3264             // Parse [pat,pat,...] as slice pattern
3265             try!(self.bump());
3266             let (before, slice, after) = try!(self.parse_pat_vec_elements());
3267             try!(self.expect(&token::CloseDelim(token::Bracket)));
3268             pat = PatVec(before, slice, after);
3269           }
3270           _ => {
3271             // At this point, token != _, &, &&, (, [
3272             if try!(self.eat_keyword(keywords::Mut)) {
3273                 // Parse mut ident @ pat
3274                 pat = try!(self.parse_pat_ident(BindByValue(MutMutable)));
3275             } else if try!(self.eat_keyword(keywords::Ref)) {
3276                 // Parse ref ident @ pat / ref mut ident @ pat
3277                 let mutbl = try!(self.parse_mutability());
3278                 pat = try!(self.parse_pat_ident(BindByRef(mutbl)));
3279             } else if try!(self.eat_keyword(keywords::Box)) {
3280                 // Parse box pat
3281                 let subpat = try!(self.parse_pat_nopanic());
3282                 pat = PatBox(subpat);
3283             } else if self.is_path_start() {
3284                 // Parse pattern starting with a path
3285                 if self.token.is_plain_ident() && self.look_ahead(1, |t| *t != token::DotDotDot &&
3286                         *t != token::OpenDelim(token::Brace) &&
3287                         *t != token::OpenDelim(token::Paren) &&
3288                         // Contrary to its definition, a plain ident can be followed by :: in macros
3289                         *t != token::ModSep) {
3290                     // Plain idents have some extra abilities here compared to general paths
3291                     if self.look_ahead(1, |t| *t == token::Not) {
3292                         // Parse macro invocation
3293                         let ident = try!(self.parse_ident());
3294                         let ident_span = self.last_span;
3295                         let path = ident_to_path(ident_span, ident);
3296                         try!(self.bump());
3297                         let delim = try!(self.expect_open_delim());
3298                         let tts = try!(self.parse_seq_to_end(&token::CloseDelim(delim),
3299                                 seq_sep_none(), |p| p.parse_token_tree()));
3300                         let mac = MacInvocTT(path, tts, EMPTY_CTXT);
3301                         pat = PatMac(codemap::Spanned {node: mac, span: self.span});
3302                     } else {
3303                         // Parse ident @ pat
3304                         // This can give false positives and parse nullary enums,
3305                         // they are dealt with later in resolve
3306                         pat = try!(self.parse_pat_ident(BindByValue(MutImmutable)));
3307                     }
3308                 } else {
3309                     let (qself, path) = if try!(self.eat_lt()) {
3310                         // Parse a qualified path
3311                         let (qself, path) =
3312                             try!(self.parse_qualified_path(NoTypesAllowed));
3313                         (Some(qself), path)
3314                     } else {
3315                         // Parse an unqualified path
3316                         (None, try!(self.parse_path(LifetimeAndTypesWithColons)))
3317                     };
3318                     match self.token {
3319                       token::DotDotDot => {
3320                         // Parse range
3321                         let hi = self.last_span.hi;
3322                         let begin = self.mk_expr(lo, hi, ExprPath(qself, path));
3323                         try!(self.bump());
3324                         let end = try!(self.parse_pat_range_end());
3325                         pat = PatRange(begin, end);
3326                       }
3327                       token::OpenDelim(token::Brace) => {
3328                          if qself.is_some() {
3329                             let span = self.span;
3330                             self.span_err(span,
3331                                           "unexpected `{` after qualified path");
3332                             self.abort_if_errors();
3333                         }
3334                        // Parse struct pattern
3335                         try!(self.bump());
3336                         let (fields, etc) = try!(self.parse_pat_fields());
3337                         try!(self.bump());
3338                         pat = PatStruct(path, fields, etc);
3339                       }
3340                       token::OpenDelim(token::Paren) => {
3341                         if qself.is_some() {
3342                             let span = self.span;
3343                             self.span_err(span,
3344                                           "unexpected `(` after qualified path");
3345                             self.abort_if_errors();
3346                         }
3347                         // Parse tuple struct or enum pattern
3348                         if self.look_ahead(1, |t| *t == token::DotDot) {
3349                             // This is a "top constructor only" pat
3350                             try!(self.bump());
3351                             try!(self.bump());
3352                             try!(self.expect(&token::CloseDelim(token::Paren)));
3353                             pat = PatEnum(path, None);
3354                         } else {
3355                             let args = try!(self.parse_enum_variant_seq(
3356                                     &token::OpenDelim(token::Paren),
3357                                     &token::CloseDelim(token::Paren),
3358                                     seq_sep_trailing_allowed(token::Comma),
3359                                     |p| p.parse_pat_nopanic()));
3360                             pat = PatEnum(path, Some(args));
3361                         }
3362                       }
3363                       _ if qself.is_some() => {
3364                         // Parse qualified path
3365                         pat = PatQPath(qself.unwrap(), path);
3366                       }
3367                       _ => {
3368                         // Parse nullary enum
3369                         pat = PatEnum(path, Some(vec![]));
3370                       }
3371                     }
3372                 }
3373             } else {
3374                 // Try to parse everything else as literal with optional minus
3375                 let begin = try!(self.parse_literal_maybe_minus());
3376                 if try!(self.eat(&token::DotDotDot)) {
3377                     let end = try!(self.parse_pat_range_end());
3378                     pat = PatRange(begin, end);
3379                 } else {
3380                     pat = PatLit(begin);
3381                 }
3382             }
3383           }
3384         }
3385
3386         let hi = self.last_span.hi;
3387         Ok(P(ast::Pat {
3388             id: ast::DUMMY_NODE_ID,
3389             node: pat,
3390             span: mk_sp(lo, hi),
3391         }))
3392     }
3393
3394     /// Parse ident or ident @ pat
3395     /// used by the copy foo and ref foo patterns to give a good
3396     /// error message when parsing mistakes like ref foo(a,b)
3397     fn parse_pat_ident(&mut self,
3398                        binding_mode: ast::BindingMode)
3399                        -> PResult<ast::Pat_> {
3400         if !self.token.is_plain_ident() {
3401             let span = self.span;
3402             let tok_str = self.this_token_to_string();
3403             return Err(self.span_fatal(span,
3404                             &format!("expected identifier, found `{}`", tok_str)))
3405         }
3406         let ident = try!(self.parse_ident());
3407         let last_span = self.last_span;
3408         let name = codemap::Spanned{span: last_span, node: ident};
3409         let sub = if try!(self.eat(&token::At) ){
3410             Some(try!(self.parse_pat_nopanic()))
3411         } else {
3412             None
3413         };
3414
3415         // just to be friendly, if they write something like
3416         //   ref Some(i)
3417         // we end up here with ( as the current token.  This shortly
3418         // leads to a parse error.  Note that if there is no explicit
3419         // binding mode then we do not end up here, because the lookahead
3420         // will direct us over to parse_enum_variant()
3421         if self.token == token::OpenDelim(token::Paren) {
3422             let last_span = self.last_span;
3423             return Err(self.span_fatal(
3424                 last_span,
3425                 "expected identifier, found enum pattern"))
3426         }
3427
3428         Ok(PatIdent(binding_mode, name, sub))
3429     }
3430
3431     /// Parse a local variable declaration
3432     fn parse_local(&mut self) -> PResult<P<Local>> {
3433         let lo = self.span.lo;
3434         let pat = try!(self.parse_pat_nopanic());
3435
3436         let mut ty = None;
3437         if try!(self.eat(&token::Colon) ){
3438             ty = Some(try!(self.parse_ty_sum()));
3439         }
3440         let init = try!(self.parse_initializer());
3441         Ok(P(ast::Local {
3442             ty: ty,
3443             pat: pat,
3444             init: init,
3445             id: ast::DUMMY_NODE_ID,
3446             span: mk_sp(lo, self.last_span.hi),
3447         }))
3448     }
3449
3450     /// Parse a "let" stmt
3451     fn parse_let(&mut self) -> PResult<P<Decl>> {
3452         let lo = self.span.lo;
3453         let local = try!(self.parse_local());
3454         Ok(P(spanned(lo, self.last_span.hi, DeclLocal(local))))
3455     }
3456
3457     /// Parse a structure field
3458     fn parse_name_and_ty(&mut self, pr: Visibility,
3459                          attrs: Vec<Attribute> ) -> PResult<StructField> {
3460         let lo = match pr {
3461             Inherited => self.span.lo,
3462             Public => self.last_span.lo,
3463         };
3464         if !self.token.is_plain_ident() {
3465             return Err(self.fatal("expected ident"));
3466         }
3467         let name = try!(self.parse_ident());
3468         try!(self.expect(&token::Colon));
3469         let ty = try!(self.parse_ty_sum());
3470         Ok(spanned(lo, self.last_span.hi, ast::StructField_ {
3471             kind: NamedField(name, pr),
3472             id: ast::DUMMY_NODE_ID,
3473             ty: ty,
3474             attrs: attrs,
3475         }))
3476     }
3477
3478     /// Emit an expected item after attributes error.
3479     fn expected_item_err(&self, attrs: &[Attribute]) {
3480         let message = match attrs.last() {
3481             Some(&Attribute { node: ast::Attribute_ { is_sugared_doc: true, .. }, .. }) => {
3482                 "expected item after doc comment"
3483             }
3484             _ => "expected item after attributes",
3485         };
3486
3487         self.span_err(self.last_span, message);
3488     }
3489
3490     /// Parse a statement. may include decl.
3491     pub fn parse_stmt_nopanic(&mut self) -> PResult<Option<P<Stmt>>> {
3492         Ok(try!(self.parse_stmt_()).map(P))
3493     }
3494
3495     fn parse_stmt_(&mut self) -> PResult<Option<Stmt>> {
3496         maybe_whole!(Some deref self, NtStmt);
3497
3498         fn check_expected_item(p: &mut Parser, attrs: &[Attribute]) {
3499             // If we have attributes then we should have an item
3500             if !attrs.is_empty() {
3501                 p.expected_item_err(attrs);
3502             }
3503         }
3504
3505         let attrs = self.parse_outer_attributes();
3506         let lo = self.span.lo;
3507
3508         Ok(Some(if self.check_keyword(keywords::Let) {
3509             check_expected_item(self, &attrs);
3510             try!(self.expect_keyword(keywords::Let));
3511             let decl = try!(self.parse_let());
3512             spanned(lo, decl.span.hi, StmtDecl(decl, ast::DUMMY_NODE_ID))
3513         } else if self.token.is_ident()
3514             && !self.token.is_any_keyword()
3515             && self.look_ahead(1, |t| *t == token::Not) {
3516             // it's a macro invocation:
3517
3518             check_expected_item(self, &attrs);
3519
3520             // Potential trouble: if we allow macros with paths instead of
3521             // idents, we'd need to look ahead past the whole path here...
3522             let pth = try!(self.parse_path(NoTypesAllowed));
3523             try!(self.bump());
3524
3525             let id = match self.token {
3526                 token::OpenDelim(_) => token::special_idents::invalid, // no special identifier
3527                 _ => try!(self.parse_ident()),
3528             };
3529
3530             // check that we're pointing at delimiters (need to check
3531             // again after the `if`, because of `parse_ident`
3532             // consuming more tokens).
3533             let delim = match self.token {
3534                 token::OpenDelim(delim) => delim,
3535                 _ => {
3536                     // we only expect an ident if we didn't parse one
3537                     // above.
3538                     let ident_str = if id.name == token::special_idents::invalid.name {
3539                         "identifier, "
3540                     } else {
3541                         ""
3542                     };
3543                     let tok_str = self.this_token_to_string();
3544                     return Err(self.fatal(&format!("expected {}`(` or `{{`, found `{}`",
3545                                        ident_str,
3546                                        tok_str)))
3547                 },
3548             };
3549
3550             let tts = try!(self.parse_unspanned_seq(
3551                 &token::OpenDelim(delim),
3552                 &token::CloseDelim(delim),
3553                 seq_sep_none(),
3554                 |p| p.parse_token_tree()
3555             ));
3556             let hi = self.last_span.hi;
3557
3558             let style = if delim == token::Brace {
3559                 MacStmtWithBraces
3560             } else {
3561                 MacStmtWithoutBraces
3562             };
3563
3564             if id.name == token::special_idents::invalid.name {
3565                 spanned(lo, hi,
3566                         StmtMac(P(spanned(lo,
3567                                           hi,
3568                                           MacInvocTT(pth, tts, EMPTY_CTXT))),
3569                                   style))
3570             } else {
3571                 // if it has a special ident, it's definitely an item
3572                 //
3573                 // Require a semicolon or braces.
3574                 if style != MacStmtWithBraces {
3575                     if !try!(self.eat(&token::Semi) ){
3576                         let last_span = self.last_span;
3577                         self.span_err(last_span,
3578                                       "macros that expand to items must \
3579                                        either be surrounded with braces or \
3580                                        followed by a semicolon");
3581                     }
3582                 }
3583                 spanned(lo, hi, StmtDecl(
3584                     P(spanned(lo, hi, DeclItem(
3585                         self.mk_item(
3586                             lo, hi, id /*id is good here*/,
3587                             ItemMac(spanned(lo, hi, MacInvocTT(pth, tts, EMPTY_CTXT))),
3588                             Inherited, Vec::new(/*no attrs*/))))),
3589                     ast::DUMMY_NODE_ID))
3590             }
3591         } else {
3592             match try!(self.parse_item_(attrs, false)) {
3593                 Some(i) => {
3594                     let hi = i.span.hi;
3595                     let decl = P(spanned(lo, hi, DeclItem(i)));
3596                     spanned(lo, hi, StmtDecl(decl, ast::DUMMY_NODE_ID))
3597                 }
3598                 None => {
3599                     // Do not attempt to parse an expression if we're done here.
3600                     if self.token == token::Semi {
3601                         try!(self.bump());
3602                         return Ok(None);
3603                     }
3604
3605                     if self.token == token::CloseDelim(token::Brace) {
3606                         return Ok(None);
3607                     }
3608
3609                     // Remainder are line-expr stmts.
3610                     let e = try!(self.parse_expr_res(Restrictions::RESTRICTION_STMT_EXPR));
3611                     spanned(lo, e.span.hi, StmtExpr(e, ast::DUMMY_NODE_ID))
3612                 }
3613             }
3614         }))
3615     }
3616
3617     /// Is this expression a successfully-parsed statement?
3618     fn expr_is_complete(&mut self, e: &Expr) -> bool {
3619         self.restrictions.contains(Restrictions::RESTRICTION_STMT_EXPR) &&
3620             !classify::expr_requires_semi_to_be_stmt(e)
3621     }
3622
3623     /// Parse a block. No inner attrs are allowed.
3624     pub fn parse_block(&mut self) -> PResult<P<Block>> {
3625         maybe_whole!(no_clone self, NtBlock);
3626
3627         let lo = self.span.lo;
3628
3629         if !try!(self.eat(&token::OpenDelim(token::Brace)) ){
3630             let sp = self.span;
3631             let tok = self.this_token_to_string();
3632             return Err(self.span_fatal_help(sp,
3633                                  &format!("expected `{{`, found `{}`", tok),
3634                                  "place this code inside a block"));
3635         }
3636
3637         self.parse_block_tail(lo, DefaultBlock)
3638     }
3639
3640     /// Parse a block. Inner attrs are allowed.
3641     fn parse_inner_attrs_and_block(&mut self) -> PResult<(Vec<Attribute>, P<Block>)> {
3642         maybe_whole!(pair_empty self, NtBlock);
3643
3644         let lo = self.span.lo;
3645         try!(self.expect(&token::OpenDelim(token::Brace)));
3646         Ok((self.parse_inner_attributes(),
3647          try!(self.parse_block_tail(lo, DefaultBlock))))
3648     }
3649
3650     /// Parse the rest of a block expression or function body
3651     /// Precondition: already parsed the '{'.
3652     fn parse_block_tail(&mut self, lo: BytePos, s: BlockCheckMode) -> PResult<P<Block>> {
3653         let mut stmts = vec![];
3654         let mut expr = None;
3655
3656         while !try!(self.eat(&token::CloseDelim(token::Brace))) {
3657             let Spanned {node, span} = if let Some(s) = try!(self.parse_stmt_()) {
3658                 s
3659             } else {
3660                 // Found only `;` or `}`.
3661                 continue;
3662             };
3663             match node {
3664                 StmtExpr(e, _) => {
3665                     try!(self.handle_expression_like_statement(e, span, &mut stmts, &mut expr));
3666                 }
3667                 StmtMac(mac, MacStmtWithoutBraces) => {
3668                     // statement macro without braces; might be an
3669                     // expr depending on whether a semicolon follows
3670                     match self.token {
3671                         token::Semi => {
3672                             stmts.push(P(Spanned {
3673                                 node: StmtMac(mac, MacStmtWithSemicolon),
3674                                 span: mk_sp(span.lo, self.span.hi),
3675                             }));
3676                             try!(self.bump());
3677                         }
3678                         _ => {
3679                             let e = self.mk_mac_expr(span.lo, span.hi,
3680                                                      mac.and_then(|m| m.node));
3681                             let e = try!(self.parse_dot_or_call_expr_with(e));
3682                             let e = try!(self.parse_more_binops(e, 0));
3683                             let e = try!(self.parse_assign_expr_with(e));
3684                             try!(self.handle_expression_like_statement(
3685                                 e,
3686                                 span,
3687                                 &mut stmts,
3688                                 &mut expr));
3689                         }
3690                     }
3691                 }
3692                 StmtMac(m, style) => {
3693                     // statement macro; might be an expr
3694                     match self.token {
3695                         token::Semi => {
3696                             stmts.push(P(Spanned {
3697                                 node: StmtMac(m, MacStmtWithSemicolon),
3698                                 span: mk_sp(span.lo, self.span.hi),
3699                             }));
3700                             try!(self.bump());
3701                         }
3702                         token::CloseDelim(token::Brace) => {
3703                             // if a block ends in `m!(arg)` without
3704                             // a `;`, it must be an expr
3705                             expr = Some(self.mk_mac_expr(span.lo, span.hi,
3706                                                          m.and_then(|x| x.node)));
3707                         }
3708                         _ => {
3709                             stmts.push(P(Spanned {
3710                                 node: StmtMac(m, style),
3711                                 span: span
3712                             }));
3713                         }
3714                     }
3715                 }
3716                 _ => { // all other kinds of statements:
3717                     let mut hi = span.hi;
3718                     if classify::stmt_ends_with_semi(&node) {
3719                         try!(self.commit_stmt_expecting(token::Semi));
3720                         hi = self.last_span.hi;
3721                     }
3722
3723                     stmts.push(P(Spanned {
3724                         node: node,
3725                         span: mk_sp(span.lo, hi)
3726                     }));
3727                 }
3728             }
3729         }
3730
3731         Ok(P(ast::Block {
3732             stmts: stmts,
3733             expr: expr,
3734             id: ast::DUMMY_NODE_ID,
3735             rules: s,
3736             span: mk_sp(lo, self.last_span.hi),
3737         }))
3738     }
3739
3740     fn handle_expression_like_statement(
3741             &mut self,
3742             e: P<Expr>,
3743             span: Span,
3744             stmts: &mut Vec<P<Stmt>>,
3745             last_block_expr: &mut Option<P<Expr>>) -> PResult<()> {
3746         // expression without semicolon
3747         if classify::expr_requires_semi_to_be_stmt(&*e) {
3748             // Just check for errors and recover; do not eat semicolon yet.
3749             try!(self.commit_stmt(&[],
3750                              &[token::Semi, token::CloseDelim(token::Brace)]));
3751         }
3752
3753         match self.token {
3754             token::Semi => {
3755                 try!(self.bump());
3756                 let span_with_semi = Span {
3757                     lo: span.lo,
3758                     hi: self.last_span.hi,
3759                     expn_id: span.expn_id,
3760                 };
3761                 stmts.push(P(Spanned {
3762                     node: StmtSemi(e, ast::DUMMY_NODE_ID),
3763                     span: span_with_semi,
3764                 }));
3765             }
3766             token::CloseDelim(token::Brace) => *last_block_expr = Some(e),
3767             _ => {
3768                 stmts.push(P(Spanned {
3769                     node: StmtExpr(e, ast::DUMMY_NODE_ID),
3770                     span: span
3771                 }));
3772             }
3773         }
3774         Ok(())
3775     }
3776
3777     // Parses a sequence of bounds if a `:` is found,
3778     // otherwise returns empty list.
3779     fn parse_colon_then_ty_param_bounds(&mut self,
3780                                         mode: BoundParsingMode)
3781                                         -> PResult<OwnedSlice<TyParamBound>>
3782     {
3783         if !try!(self.eat(&token::Colon) ){
3784             Ok(OwnedSlice::empty())
3785         } else {
3786             self.parse_ty_param_bounds(mode)
3787         }
3788     }
3789
3790     // matches bounds    = ( boundseq )?
3791     // where   boundseq  = ( polybound + boundseq ) | polybound
3792     // and     polybound = ( 'for' '<' 'region '>' )? bound
3793     // and     bound     = 'region | trait_ref
3794     fn parse_ty_param_bounds(&mut self,
3795                              mode: BoundParsingMode)
3796                              -> PResult<OwnedSlice<TyParamBound>>
3797     {
3798         let mut result = vec!();
3799         loop {
3800             let question_span = self.span;
3801             let ate_question = try!(self.eat(&token::Question));
3802             match self.token {
3803                 token::Lifetime(lifetime) => {
3804                     if ate_question {
3805                         self.span_err(question_span,
3806                                       "`?` may only modify trait bounds, not lifetime bounds");
3807                     }
3808                     result.push(RegionTyParamBound(ast::Lifetime {
3809                         id: ast::DUMMY_NODE_ID,
3810                         span: self.span,
3811                         name: lifetime.name
3812                     }));
3813                     try!(self.bump());
3814                 }
3815                 token::ModSep | token::Ident(..) => {
3816                     let poly_trait_ref = try!(self.parse_poly_trait_ref());
3817                     let modifier = if ate_question {
3818                         if mode == BoundParsingMode::Modified {
3819                             TraitBoundModifier::Maybe
3820                         } else {
3821                             self.span_err(question_span,
3822                                           "unexpected `?`");
3823                             TraitBoundModifier::None
3824                         }
3825                     } else {
3826                         TraitBoundModifier::None
3827                     };
3828                     result.push(TraitTyParamBound(poly_trait_ref, modifier))
3829                 }
3830                 _ => break,
3831             }
3832
3833             if !try!(self.eat(&token::BinOp(token::Plus)) ){
3834                 break;
3835             }
3836         }
3837
3838         return Ok(OwnedSlice::from_vec(result));
3839     }
3840
3841     /// Matches typaram = IDENT (`?` unbound)? optbounds ( EQ ty )?
3842     fn parse_ty_param(&mut self) -> PResult<TyParam> {
3843         let span = self.span;
3844         let ident = try!(self.parse_ident());
3845
3846         let bounds = try!(self.parse_colon_then_ty_param_bounds(BoundParsingMode::Modified));
3847
3848         let default = if self.check(&token::Eq) {
3849             try!(self.bump());
3850             Some(try!(self.parse_ty_sum()))
3851         } else {
3852             None
3853         };
3854
3855         Ok(TyParam {
3856             ident: ident,
3857             id: ast::DUMMY_NODE_ID,
3858             bounds: bounds,
3859             default: default,
3860             span: span,
3861         })
3862     }
3863
3864     /// Parse a set of optional generic type parameter declarations. Where
3865     /// clauses are not parsed here, and must be added later via
3866     /// `parse_where_clause()`.
3867     ///
3868     /// matches generics = ( ) | ( < > ) | ( < typaramseq ( , )? > ) | ( < lifetimes ( , )? > )
3869     ///                  | ( < lifetimes , typaramseq ( , )? > )
3870     /// where   typaramseq = ( typaram ) | ( typaram , typaramseq )
3871     pub fn parse_generics(&mut self) -> PResult<ast::Generics> {
3872         maybe_whole!(self, NtGenerics);
3873
3874         if try!(self.eat(&token::Lt) ){
3875             let lifetime_defs = try!(self.parse_lifetime_defs());
3876             let mut seen_default = false;
3877             let ty_params = try!(self.parse_seq_to_gt(Some(token::Comma), |p| {
3878                 try!(p.forbid_lifetime());
3879                 let ty_param = try!(p.parse_ty_param());
3880                 if ty_param.default.is_some() {
3881                     seen_default = true;
3882                 } else if seen_default {
3883                     let last_span = p.last_span;
3884                     p.span_err(last_span,
3885                                "type parameters with a default must be trailing");
3886                 }
3887                 Ok(ty_param)
3888             }));
3889             Ok(ast::Generics {
3890                 lifetimes: lifetime_defs,
3891                 ty_params: ty_params,
3892                 where_clause: WhereClause {
3893                     id: ast::DUMMY_NODE_ID,
3894                     predicates: Vec::new(),
3895                 }
3896             })
3897         } else {
3898             Ok(ast_util::empty_generics())
3899         }
3900     }
3901
3902     fn parse_generic_values_after_lt(&mut self) -> PResult<(Vec<ast::Lifetime>,
3903                                                             Vec<P<Ty>>,
3904                                                             Vec<P<TypeBinding>>)> {
3905         let span_lo = self.span.lo;
3906         let lifetimes = try!(self.parse_lifetimes(token::Comma));
3907
3908         let missing_comma = !lifetimes.is_empty() &&
3909                             !self.token.is_like_gt() &&
3910                             self.last_token
3911                                 .as_ref().map_or(true,
3912                                                  |x| &**x != &token::Comma);
3913
3914         if missing_comma {
3915
3916             let msg = format!("expected `,` or `>` after lifetime \
3917                               name, found `{}`",
3918                               self.this_token_to_string());
3919             self.span_err(self.span, &msg);
3920
3921             let span_hi = self.span.hi;
3922             let span_hi = if self.parse_ty_nopanic().is_ok() {
3923                 self.span.hi
3924             } else {
3925                 span_hi
3926             };
3927
3928             let msg = format!("did you mean a single argument type &'a Type, \
3929                               or did you mean the comma-separated arguments \
3930                               'a, Type?");
3931             self.span_note(mk_sp(span_lo, span_hi), &msg);
3932
3933             self.abort_if_errors()
3934         }
3935
3936         // First parse types.
3937         let (types, returned) = try!(self.parse_seq_to_gt_or_return(
3938             Some(token::Comma),
3939             |p| {
3940                 try!(p.forbid_lifetime());
3941                 if p.look_ahead(1, |t| t == &token::Eq) {
3942                     Ok(None)
3943                 } else {
3944                     Ok(Some(try!(p.parse_ty_sum())))
3945                 }
3946             }
3947         ));
3948
3949         // If we found the `>`, don't continue.
3950         if !returned {
3951             return Ok((lifetimes, types.into_vec(), Vec::new()));
3952         }
3953
3954         // Then parse type bindings.
3955         let bindings = try!(self.parse_seq_to_gt(
3956             Some(token::Comma),
3957             |p| {
3958                 try!(p.forbid_lifetime());
3959                 let lo = p.span.lo;
3960                 let ident = try!(p.parse_ident());
3961                 let found_eq = try!(p.eat(&token::Eq));
3962                 if !found_eq {
3963                     let span = p.span;
3964                     p.span_warn(span, "whoops, no =?");
3965                 }
3966                 let ty = try!(p.parse_ty_nopanic());
3967                 let hi = ty.span.hi;
3968                 let span = mk_sp(lo, hi);
3969                 return Ok(P(TypeBinding{id: ast::DUMMY_NODE_ID,
3970                     ident: ident,
3971                     ty: ty,
3972                     span: span,
3973                 }));
3974             }
3975         ));
3976         Ok((lifetimes, types.into_vec(), bindings.into_vec()))
3977     }
3978
3979     fn forbid_lifetime(&mut self) -> PResult<()> {
3980         if self.token.is_lifetime() {
3981             let span = self.span;
3982             return Err(self.span_fatal(span, "lifetime parameters must be declared \
3983                                         prior to type parameters"))
3984         }
3985         Ok(())
3986     }
3987
3988     /// Parses an optional `where` clause and places it in `generics`.
3989     ///
3990     /// ```
3991     /// where T : Trait<U, V> + 'b, 'a : 'b
3992     /// ```
3993     pub fn parse_where_clause(&mut self) -> PResult<ast::WhereClause> {
3994         maybe_whole!(self, NtWhereClause);
3995
3996         let mut where_clause = WhereClause {
3997             id: ast::DUMMY_NODE_ID,
3998             predicates: Vec::new(),
3999         };
4000
4001         if !try!(self.eat_keyword(keywords::Where)) {
4002             return Ok(where_clause);
4003         }
4004
4005         let mut parsed_something = false;
4006         loop {
4007             let lo = self.span.lo;
4008             match self.token {
4009                 token::OpenDelim(token::Brace) => {
4010                     break
4011                 }
4012
4013                 token::Lifetime(..) => {
4014                     let bounded_lifetime =
4015                         try!(self.parse_lifetime());
4016
4017                     try!(self.eat(&token::Colon));
4018
4019                     let bounds =
4020                         try!(self.parse_lifetimes(token::BinOp(token::Plus)));
4021
4022                     let hi = self.last_span.hi;
4023                     let span = mk_sp(lo, hi);
4024
4025                     where_clause.predicates.push(ast::WherePredicate::RegionPredicate(
4026                         ast::WhereRegionPredicate {
4027                             span: span,
4028                             lifetime: bounded_lifetime,
4029                             bounds: bounds
4030                         }
4031                     ));
4032
4033                     parsed_something = true;
4034                 }
4035
4036                 _ => {
4037                     let bound_lifetimes = if try!(self.eat_keyword(keywords::For) ){
4038                         // Higher ranked constraint.
4039                         try!(self.expect(&token::Lt));
4040                         let lifetime_defs = try!(self.parse_lifetime_defs());
4041                         try!(self.expect_gt());
4042                         lifetime_defs
4043                     } else {
4044                         vec![]
4045                     };
4046
4047                     let bounded_ty = try!(self.parse_ty_nopanic());
4048
4049                     if try!(self.eat(&token::Colon) ){
4050                         let bounds = try!(self.parse_ty_param_bounds(BoundParsingMode::Bare));
4051                         let hi = self.last_span.hi;
4052                         let span = mk_sp(lo, hi);
4053
4054                         if bounds.is_empty() {
4055                             self.span_err(span,
4056                                           "each predicate in a `where` clause must have \
4057                                            at least one bound in it");
4058                         }
4059
4060                         where_clause.predicates.push(ast::WherePredicate::BoundPredicate(
4061                                 ast::WhereBoundPredicate {
4062                                     span: span,
4063                                     bound_lifetimes: bound_lifetimes,
4064                                     bounded_ty: bounded_ty,
4065                                     bounds: bounds,
4066                         }));
4067
4068                         parsed_something = true;
4069                     } else if try!(self.eat(&token::Eq) ){
4070                         // let ty = try!(self.parse_ty_nopanic());
4071                         let hi = self.last_span.hi;
4072                         let span = mk_sp(lo, hi);
4073                         // where_clause.predicates.push(
4074                         //     ast::WherePredicate::EqPredicate(ast::WhereEqPredicate {
4075                         //         id: ast::DUMMY_NODE_ID,
4076                         //         span: span,
4077                         //         path: panic!("NYI"), //bounded_ty,
4078                         //         ty: ty,
4079                         // }));
4080                         // parsed_something = true;
4081                         // // FIXME(#18433)
4082                         self.span_err(span,
4083                                      "equality constraints are not yet supported \
4084                                      in where clauses (#20041)");
4085                     } else {
4086                         let last_span = self.last_span;
4087                         self.span_err(last_span,
4088                               "unexpected token in `where` clause");
4089                     }
4090                 }
4091             };
4092
4093             if !try!(self.eat(&token::Comma) ){
4094                 break
4095             }
4096         }
4097
4098         if !parsed_something {
4099             let last_span = self.last_span;
4100             self.span_err(last_span,
4101                           "a `where` clause must have at least one predicate \
4102                            in it");
4103         }
4104
4105         Ok(where_clause)
4106     }
4107
4108     fn parse_fn_args(&mut self, named_args: bool, allow_variadic: bool)
4109                      -> PResult<(Vec<Arg> , bool)> {
4110         let sp = self.span;
4111         let mut args: Vec<Option<Arg>> =
4112             try!(self.parse_unspanned_seq(
4113                 &token::OpenDelim(token::Paren),
4114                 &token::CloseDelim(token::Paren),
4115                 seq_sep_trailing_allowed(token::Comma),
4116                 |p| {
4117                     if p.token == token::DotDotDot {
4118                         try!(p.bump());
4119                         if allow_variadic {
4120                             if p.token != token::CloseDelim(token::Paren) {
4121                                 let span = p.span;
4122                                 return Err(p.span_fatal(span,
4123                                     "`...` must be last in argument list for variadic function"))
4124                             }
4125                         } else {
4126                             let span = p.span;
4127                             return Err(p.span_fatal(span,
4128                                          "only foreign functions are allowed to be variadic"))
4129                         }
4130                         Ok(None)
4131                     } else {
4132                         Ok(Some(try!(p.parse_arg_general(named_args))))
4133                     }
4134                 }
4135             ));
4136
4137         let variadic = match args.pop() {
4138             Some(None) => true,
4139             Some(x) => {
4140                 // Need to put back that last arg
4141                 args.push(x);
4142                 false
4143             }
4144             None => false
4145         };
4146
4147         if variadic && args.is_empty() {
4148             self.span_err(sp,
4149                           "variadic function must be declared with at least one named argument");
4150         }
4151
4152         let args = args.into_iter().map(|x| x.unwrap()).collect();
4153
4154         Ok((args, variadic))
4155     }
4156
4157     /// Parse the argument list and result type of a function declaration
4158     pub fn parse_fn_decl(&mut self, allow_variadic: bool) -> PResult<P<FnDecl>> {
4159
4160         let (args, variadic) = try!(self.parse_fn_args(true, allow_variadic));
4161         let ret_ty = try!(self.parse_ret_ty());
4162
4163         Ok(P(FnDecl {
4164             inputs: args,
4165             output: ret_ty,
4166             variadic: variadic
4167         }))
4168     }
4169
4170     fn is_self_ident(&mut self) -> bool {
4171         match self.token {
4172           token::Ident(id, token::Plain) => id.name == special_idents::self_.name,
4173           _ => false
4174         }
4175     }
4176
4177     fn expect_self_ident(&mut self) -> PResult<ast::Ident> {
4178         match self.token {
4179             token::Ident(id, token::Plain) if id.name == special_idents::self_.name => {
4180                 try!(self.bump());
4181                 Ok(id)
4182             },
4183             _ => {
4184                 let token_str = self.this_token_to_string();
4185                 return Err(self.fatal(&format!("expected `self`, found `{}`",
4186                                    token_str)))
4187             }
4188         }
4189     }
4190
4191     fn is_self_type_ident(&mut self) -> bool {
4192         match self.token {
4193           token::Ident(id, token::Plain) => id.name == special_idents::type_self.name,
4194           _ => false
4195         }
4196     }
4197
4198     fn expect_self_type_ident(&mut self) -> PResult<ast::Ident> {
4199         match self.token {
4200             token::Ident(id, token::Plain) if id.name == special_idents::type_self.name => {
4201                 try!(self.bump());
4202                 Ok(id)
4203             },
4204             _ => {
4205                 let token_str = self.this_token_to_string();
4206                 Err(self.fatal(&format!("expected `Self`, found `{}`",
4207                                    token_str)))
4208             }
4209         }
4210     }
4211
4212     /// Parse the argument list and result type of a function
4213     /// that may have a self type.
4214     fn parse_fn_decl_with_self<F>(&mut self,
4215                                   parse_arg_fn: F) -> PResult<(ExplicitSelf, P<FnDecl>)> where
4216         F: FnMut(&mut Parser) -> PResult<Arg>,
4217     {
4218         fn maybe_parse_borrowed_explicit_self(this: &mut Parser)
4219                                               -> PResult<ast::ExplicitSelf_> {
4220             // The following things are possible to see here:
4221             //
4222             //     fn(&mut self)
4223             //     fn(&mut self)
4224             //     fn(&'lt self)
4225             //     fn(&'lt mut self)
4226             //
4227             // We already know that the current token is `&`.
4228
4229             if this.look_ahead(1, |t| t.is_keyword(keywords::SelfValue)) {
4230                 try!(this.bump());
4231                 Ok(SelfRegion(None, MutImmutable, try!(this.expect_self_ident())))
4232             } else if this.look_ahead(1, |t| t.is_mutability()) &&
4233                       this.look_ahead(2, |t| t.is_keyword(keywords::SelfValue)) {
4234                 try!(this.bump());
4235                 let mutability = try!(this.parse_mutability());
4236                 Ok(SelfRegion(None, mutability, try!(this.expect_self_ident())))
4237             } else if this.look_ahead(1, |t| t.is_lifetime()) &&
4238                       this.look_ahead(2, |t| t.is_keyword(keywords::SelfValue)) {
4239                 try!(this.bump());
4240                 let lifetime = try!(this.parse_lifetime());
4241                 Ok(SelfRegion(Some(lifetime), MutImmutable, try!(this.expect_self_ident())))
4242             } else if this.look_ahead(1, |t| t.is_lifetime()) &&
4243                       this.look_ahead(2, |t| t.is_mutability()) &&
4244                       this.look_ahead(3, |t| t.is_keyword(keywords::SelfValue)) {
4245                 try!(this.bump());
4246                 let lifetime = try!(this.parse_lifetime());
4247                 let mutability = try!(this.parse_mutability());
4248                 Ok(SelfRegion(Some(lifetime), mutability, try!(this.expect_self_ident())))
4249             } else {
4250                 Ok(SelfStatic)
4251             }
4252         }
4253
4254         try!(self.expect(&token::OpenDelim(token::Paren)));
4255
4256         // A bit of complexity and lookahead is needed here in order to be
4257         // backwards compatible.
4258         let lo = self.span.lo;
4259         let mut self_ident_lo = self.span.lo;
4260         let mut self_ident_hi = self.span.hi;
4261
4262         let mut mutbl_self = MutImmutable;
4263         let explicit_self = match self.token {
4264             token::BinOp(token::And) => {
4265                 let eself = try!(maybe_parse_borrowed_explicit_self(self));
4266                 self_ident_lo = self.last_span.lo;
4267                 self_ident_hi = self.last_span.hi;
4268                 eself
4269             }
4270             token::BinOp(token::Star) => {
4271                 // Possibly "*self" or "*mut self" -- not supported. Try to avoid
4272                 // emitting cryptic "unexpected token" errors.
4273                 try!(self.bump());
4274                 let _mutability = if self.token.is_mutability() {
4275                     try!(self.parse_mutability())
4276                 } else {
4277                     MutImmutable
4278                 };
4279                 if self.is_self_ident() {
4280                     let span = self.span;
4281                     self.span_err(span, "cannot pass self by raw pointer");
4282                     try!(self.bump());
4283                 }
4284                 // error case, making bogus self ident:
4285                 SelfValue(special_idents::self_)
4286             }
4287             token::Ident(..) => {
4288                 if self.is_self_ident() {
4289                     let self_ident = try!(self.expect_self_ident());
4290
4291                     // Determine whether this is the fully explicit form, `self:
4292                     // TYPE`.
4293                     if try!(self.eat(&token::Colon) ){
4294                         SelfExplicit(try!(self.parse_ty_sum()), self_ident)
4295                     } else {
4296                         SelfValue(self_ident)
4297                     }
4298                 } else if self.token.is_mutability() &&
4299                         self.look_ahead(1, |t| t.is_keyword(keywords::SelfValue)) {
4300                     mutbl_self = try!(self.parse_mutability());
4301                     let self_ident = try!(self.expect_self_ident());
4302
4303                     // Determine whether this is the fully explicit form,
4304                     // `self: TYPE`.
4305                     if try!(self.eat(&token::Colon) ){
4306                         SelfExplicit(try!(self.parse_ty_sum()), self_ident)
4307                     } else {
4308                         SelfValue(self_ident)
4309                     }
4310                 } else {
4311                     SelfStatic
4312                 }
4313             }
4314             _ => SelfStatic,
4315         };
4316
4317         let explicit_self_sp = mk_sp(self_ident_lo, self_ident_hi);
4318
4319         // shared fall-through for the three cases below. borrowing prevents simply
4320         // writing this as a closure
4321         macro_rules! parse_remaining_arguments {
4322             ($self_id:ident) =>
4323             {
4324             // If we parsed a self type, expect a comma before the argument list.
4325             match self.token {
4326                 token::Comma => {
4327                     try!(self.bump());
4328                     let sep = seq_sep_trailing_allowed(token::Comma);
4329                     let mut fn_inputs = try!(self.parse_seq_to_before_end(
4330                         &token::CloseDelim(token::Paren),
4331                         sep,
4332                         parse_arg_fn
4333                     ));
4334                     fn_inputs.insert(0, Arg::new_self(explicit_self_sp, mutbl_self, $self_id));
4335                     fn_inputs
4336                 }
4337                 token::CloseDelim(token::Paren) => {
4338                     vec!(Arg::new_self(explicit_self_sp, mutbl_self, $self_id))
4339                 }
4340                 _ => {
4341                     let token_str = self.this_token_to_string();
4342                     return Err(self.fatal(&format!("expected `,` or `)`, found `{}`",
4343                                        token_str)))
4344                 }
4345             }
4346             }
4347         }
4348
4349         let fn_inputs = match explicit_self {
4350             SelfStatic =>  {
4351                 let sep = seq_sep_trailing_allowed(token::Comma);
4352                 try!(self.parse_seq_to_before_end(&token::CloseDelim(token::Paren),
4353                                                   sep, parse_arg_fn))
4354             }
4355             SelfValue(id) => parse_remaining_arguments!(id),
4356             SelfRegion(_,_,id) => parse_remaining_arguments!(id),
4357             SelfExplicit(_,id) => parse_remaining_arguments!(id),
4358         };
4359
4360
4361         try!(self.expect(&token::CloseDelim(token::Paren)));
4362
4363         let hi = self.span.hi;
4364
4365         let ret_ty = try!(self.parse_ret_ty());
4366
4367         let fn_decl = P(FnDecl {
4368             inputs: fn_inputs,
4369             output: ret_ty,
4370             variadic: false
4371         });
4372
4373         Ok((spanned(lo, hi, explicit_self), fn_decl))
4374     }
4375
4376     // parse the |arg, arg| header on a lambda
4377     fn parse_fn_block_decl(&mut self) -> PResult<P<FnDecl>> {
4378         let inputs_captures = {
4379             if try!(self.eat(&token::OrOr) ){
4380                 Vec::new()
4381             } else {
4382                 try!(self.expect(&token::BinOp(token::Or)));
4383                 try!(self.parse_obsolete_closure_kind());
4384                 let args = try!(self.parse_seq_to_before_end(
4385                     &token::BinOp(token::Or),
4386                     seq_sep_trailing_allowed(token::Comma),
4387                     |p| p.parse_fn_block_arg()
4388                 ));
4389                 try!(self.bump());
4390                 args
4391             }
4392         };
4393         let output = try!(self.parse_ret_ty());
4394
4395         Ok(P(FnDecl {
4396             inputs: inputs_captures,
4397             output: output,
4398             variadic: false
4399         }))
4400     }
4401
4402     /// Parse the name and optional generic types of a function header.
4403     fn parse_fn_header(&mut self) -> PResult<(Ident, ast::Generics)> {
4404         let id = try!(self.parse_ident());
4405         let generics = try!(self.parse_generics());
4406         Ok((id, generics))
4407     }
4408
4409     fn mk_item(&mut self, lo: BytePos, hi: BytePos, ident: Ident,
4410                node: Item_, vis: Visibility,
4411                attrs: Vec<Attribute>) -> P<Item> {
4412         P(Item {
4413             ident: ident,
4414             attrs: attrs,
4415             id: ast::DUMMY_NODE_ID,
4416             node: node,
4417             vis: vis,
4418             span: mk_sp(lo, hi)
4419         })
4420     }
4421
4422     /// Parse an item-position function declaration.
4423     fn parse_item_fn(&mut self,
4424                      unsafety: Unsafety,
4425                      constness: Constness,
4426                      abi: abi::Abi)
4427                      -> PResult<ItemInfo> {
4428         let (ident, mut generics) = try!(self.parse_fn_header());
4429         let decl = try!(self.parse_fn_decl(false));
4430         generics.where_clause = try!(self.parse_where_clause());
4431         let (inner_attrs, body) = try!(self.parse_inner_attrs_and_block());
4432         Ok((ident, ItemFn(decl, unsafety, constness, abi, generics, body), Some(inner_attrs)))
4433     }
4434
4435     /// true if we are looking at `const ID`, false for things like `const fn` etc
4436     pub fn is_const_item(&mut self) -> bool {
4437         self.token.is_keyword(keywords::Const) &&
4438             !self.look_ahead(1, |t| t.is_keyword(keywords::Fn))
4439     }
4440
4441     /// parses all the "front matter" for a `fn` declaration, up to
4442     /// and including the `fn` keyword:
4443     ///
4444     /// - `const fn`
4445     /// - `unsafe fn`
4446     /// - `extern fn`
4447     /// - etc
4448     pub fn parse_fn_front_matter(&mut self) -> PResult<(ast::Constness, ast::Unsafety, abi::Abi)> {
4449         let is_const_fn = try!(self.eat_keyword(keywords::Const));
4450         let (constness, unsafety, abi) = if is_const_fn {
4451             (Constness::Const, Unsafety::Normal, abi::Rust)
4452         } else {
4453             let unsafety = try!(self.parse_unsafety());
4454             let abi = if try!(self.eat_keyword(keywords::Extern)) {
4455                 try!(self.parse_opt_abi()).unwrap_or(abi::C)
4456             } else {
4457                 abi::Rust
4458             };
4459             (Constness::NotConst, unsafety, abi)
4460         };
4461         try!(self.expect_keyword(keywords::Fn));
4462         Ok((constness, unsafety, abi))
4463     }
4464
4465     /// Parse an impl item.
4466     pub fn parse_impl_item(&mut self) -> PResult<P<ImplItem>> {
4467         maybe_whole!(no_clone self, NtImplItem);
4468
4469         let mut attrs = self.parse_outer_attributes();
4470         let lo = self.span.lo;
4471         let vis = try!(self.parse_visibility());
4472         let (name, node) = if try!(self.eat_keyword(keywords::Type)) {
4473             let name = try!(self.parse_ident());
4474             try!(self.expect(&token::Eq));
4475             let typ = try!(self.parse_ty_sum());
4476             try!(self.expect(&token::Semi));
4477             (name, TypeImplItem(typ))
4478         } else if self.is_const_item() {
4479             try!(self.expect_keyword(keywords::Const));
4480             let name = try!(self.parse_ident());
4481             try!(self.expect(&token::Colon));
4482             let typ = try!(self.parse_ty_sum());
4483             try!(self.expect(&token::Eq));
4484             let expr = try!(self.parse_expr_nopanic());
4485             try!(self.commit_expr_expecting(&expr, token::Semi));
4486             (name, ConstImplItem(typ, expr))
4487         } else {
4488             let (name, inner_attrs, node) = try!(self.parse_impl_method(vis));
4489             attrs.extend(inner_attrs);
4490             (name, node)
4491         };
4492
4493         Ok(P(ImplItem {
4494             id: ast::DUMMY_NODE_ID,
4495             span: mk_sp(lo, self.last_span.hi),
4496             ident: name,
4497             vis: vis,
4498             attrs: attrs,
4499             node: node
4500         }))
4501     }
4502
4503     fn complain_if_pub_macro(&mut self, visa: Visibility, span: Span) {
4504         match visa {
4505             Public => {
4506                 self.span_err(span, "can't qualify macro invocation with `pub`");
4507                 self.fileline_help(span, "try adjusting the macro to put `pub` inside \
4508                                       the invocation");
4509             }
4510             Inherited => (),
4511         }
4512     }
4513
4514     /// Parse a method or a macro invocation in a trait impl.
4515     fn parse_impl_method(&mut self, vis: Visibility)
4516                          -> PResult<(Ident, Vec<ast::Attribute>, ast::ImplItem_)> {
4517         // code copied from parse_macro_use_or_failure... abstraction!
4518         if !self.token.is_any_keyword()
4519             && self.look_ahead(1, |t| *t == token::Not)
4520             && (self.look_ahead(2, |t| *t == token::OpenDelim(token::Paren))
4521                 || self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))) {
4522             // method macro.
4523
4524             let last_span = self.last_span;
4525             self.complain_if_pub_macro(vis, last_span);
4526
4527             let pth = try!(self.parse_path(NoTypesAllowed));
4528             try!(self.expect(&token::Not));
4529
4530             // eat a matched-delimiter token tree:
4531             let delim = try!(self.expect_open_delim());
4532             let tts = try!(self.parse_seq_to_end(&token::CloseDelim(delim),
4533                                             seq_sep_none(),
4534                                             |p| p.parse_token_tree()));
4535             let m_ = ast::MacInvocTT(pth, tts, EMPTY_CTXT);
4536             let m: ast::Mac = codemap::Spanned { node: m_,
4537                                                 span: mk_sp(self.span.lo,
4538                                                             self.span.hi) };
4539             if delim != token::Brace {
4540                 try!(self.expect(&token::Semi))
4541             }
4542             Ok((token::special_idents::invalid, vec![], ast::MacImplItem(m)))
4543         } else {
4544             let (constness, unsafety, abi) = try!(self.parse_fn_front_matter());
4545             let ident = try!(self.parse_ident());
4546             let mut generics = try!(self.parse_generics());
4547             let (explicit_self, decl) = try!(self.parse_fn_decl_with_self(|p| {
4548                     p.parse_arg()
4549                 }));
4550             generics.where_clause = try!(self.parse_where_clause());
4551             let (inner_attrs, body) = try!(self.parse_inner_attrs_and_block());
4552             Ok((ident, inner_attrs, MethodImplItem(ast::MethodSig {
4553                 generics: generics,
4554                 abi: abi,
4555                 explicit_self: explicit_self,
4556                 unsafety: unsafety,
4557                 constness: constness,
4558                 decl: decl
4559              }, body)))
4560         }
4561     }
4562
4563     /// Parse trait Foo { ... }
4564     fn parse_item_trait(&mut self, unsafety: Unsafety) -> PResult<ItemInfo> {
4565
4566         let ident = try!(self.parse_ident());
4567         let mut tps = try!(self.parse_generics());
4568
4569         // Parse supertrait bounds.
4570         let bounds = try!(self.parse_colon_then_ty_param_bounds(BoundParsingMode::Bare));
4571
4572         tps.where_clause = try!(self.parse_where_clause());
4573
4574         let meths = try!(self.parse_trait_items());
4575         Ok((ident, ItemTrait(unsafety, tps, bounds, meths), None))
4576     }
4577
4578     /// Parses items implementations variants
4579     ///    impl<T> Foo { ... }
4580     ///    impl<T> ToString for &'static T { ... }
4581     ///    impl Send for .. {}
4582     fn parse_item_impl(&mut self, unsafety: ast::Unsafety) -> PResult<ItemInfo> {
4583         let impl_span = self.span;
4584
4585         // First, parse type parameters if necessary.
4586         let mut generics = try!(self.parse_generics());
4587
4588         // Special case: if the next identifier that follows is '(', don't
4589         // allow this to be parsed as a trait.
4590         let could_be_trait = self.token != token::OpenDelim(token::Paren);
4591
4592         let neg_span = self.span;
4593         let polarity = if try!(self.eat(&token::Not) ){
4594             ast::ImplPolarity::Negative
4595         } else {
4596             ast::ImplPolarity::Positive
4597         };
4598
4599         // Parse the trait.
4600         let mut ty = try!(self.parse_ty_sum());
4601
4602         // Parse traits, if necessary.
4603         let opt_trait = if could_be_trait && try!(self.eat_keyword(keywords::For) ){
4604             // New-style trait. Reinterpret the type as a trait.
4605             match ty.node {
4606                 TyPath(None, ref path) => {
4607                     Some(TraitRef {
4608                         path: (*path).clone(),
4609                         ref_id: ty.id,
4610                     })
4611                 }
4612                 _ => {
4613                     self.span_err(ty.span, "not a trait");
4614                     None
4615                 }
4616             }
4617         } else {
4618             match polarity {
4619                 ast::ImplPolarity::Negative => {
4620                     // This is a negated type implementation
4621                     // `impl !MyType {}`, which is not allowed.
4622                     self.span_err(neg_span, "inherent implementation can't be negated");
4623                 },
4624                 _ => {}
4625             }
4626             None
4627         };
4628
4629         if opt_trait.is_some() && try!(self.eat(&token::DotDot) ){
4630             if generics.is_parameterized() {
4631                 self.span_err(impl_span, "default trait implementations are not \
4632                                           allowed to have generics");
4633             }
4634
4635             try!(self.expect(&token::OpenDelim(token::Brace)));
4636             try!(self.expect(&token::CloseDelim(token::Brace)));
4637             Ok((ast_util::impl_pretty_name(&opt_trait, None),
4638              ItemDefaultImpl(unsafety, opt_trait.unwrap()), None))
4639         } else {
4640             if opt_trait.is_some() {
4641                 ty = try!(self.parse_ty_sum());
4642             }
4643             generics.where_clause = try!(self.parse_where_clause());
4644
4645             try!(self.expect(&token::OpenDelim(token::Brace)));
4646             let attrs = self.parse_inner_attributes();
4647
4648             let mut impl_items = vec![];
4649             while !try!(self.eat(&token::CloseDelim(token::Brace))) {
4650                 impl_items.push(try!(self.parse_impl_item()));
4651             }
4652
4653             Ok((ast_util::impl_pretty_name(&opt_trait, Some(&*ty)),
4654              ItemImpl(unsafety, polarity, generics, opt_trait, ty, impl_items),
4655              Some(attrs)))
4656         }
4657     }
4658
4659     /// Parse a::B<String,i32>
4660     fn parse_trait_ref(&mut self) -> PResult<TraitRef> {
4661         Ok(ast::TraitRef {
4662             path: try!(self.parse_path(LifetimeAndTypesWithoutColons)),
4663             ref_id: ast::DUMMY_NODE_ID,
4664         })
4665     }
4666
4667     fn parse_late_bound_lifetime_defs(&mut self) -> PResult<Vec<ast::LifetimeDef>> {
4668         if try!(self.eat_keyword(keywords::For) ){
4669             try!(self.expect(&token::Lt));
4670             let lifetime_defs = try!(self.parse_lifetime_defs());
4671             try!(self.expect_gt());
4672             Ok(lifetime_defs)
4673         } else {
4674             Ok(Vec::new())
4675         }
4676     }
4677
4678     /// Parse for<'l> a::B<String,i32>
4679     fn parse_poly_trait_ref(&mut self) -> PResult<PolyTraitRef> {
4680         let lo = self.span.lo;
4681         let lifetime_defs = try!(self.parse_late_bound_lifetime_defs());
4682
4683         Ok(ast::PolyTraitRef {
4684             bound_lifetimes: lifetime_defs,
4685             trait_ref: try!(self.parse_trait_ref()),
4686             span: mk_sp(lo, self.last_span.hi),
4687         })
4688     }
4689
4690     /// Parse struct Foo { ... }
4691     fn parse_item_struct(&mut self) -> PResult<ItemInfo> {
4692         let class_name = try!(self.parse_ident());
4693         let mut generics = try!(self.parse_generics());
4694
4695         // There is a special case worth noting here, as reported in issue #17904.
4696         // If we are parsing a tuple struct it is the case that the where clause
4697         // should follow the field list. Like so:
4698         //
4699         // struct Foo<T>(T) where T: Copy;
4700         //
4701         // If we are parsing a normal record-style struct it is the case
4702         // that the where clause comes before the body, and after the generics.
4703         // So if we look ahead and see a brace or a where-clause we begin
4704         // parsing a record style struct.
4705         //
4706         // Otherwise if we look ahead and see a paren we parse a tuple-style
4707         // struct.
4708
4709         let (fields, ctor_id) = if self.token.is_keyword(keywords::Where) {
4710             generics.where_clause = try!(self.parse_where_clause());
4711             if try!(self.eat(&token::Semi)) {
4712                 // If we see a: `struct Foo<T> where T: Copy;` style decl.
4713                 (Vec::new(), Some(ast::DUMMY_NODE_ID))
4714             } else {
4715                 // If we see: `struct Foo<T> where T: Copy { ... }`
4716                 (try!(self.parse_record_struct_body(&class_name)), None)
4717             }
4718         // No `where` so: `struct Foo<T>;`
4719         } else if try!(self.eat(&token::Semi) ){
4720             (Vec::new(), Some(ast::DUMMY_NODE_ID))
4721         // Record-style struct definition
4722         } else if self.token == token::OpenDelim(token::Brace) {
4723             let fields = try!(self.parse_record_struct_body(&class_name));
4724             (fields, None)
4725         // Tuple-style struct definition with optional where-clause.
4726         } else if self.token == token::OpenDelim(token::Paren) {
4727             let fields = try!(self.parse_tuple_struct_body(&class_name, &mut generics));
4728             (fields, Some(ast::DUMMY_NODE_ID))
4729         } else {
4730             let token_str = self.this_token_to_string();
4731             return Err(self.fatal(&format!("expected `where`, `{{`, `(`, or `;` after struct \
4732                                             name, found `{}`", token_str)))
4733         };
4734
4735         Ok((class_name,
4736          ItemStruct(P(ast::StructDef {
4737              fields: fields,
4738              ctor_id: ctor_id,
4739          }), generics),
4740          None))
4741     }
4742
4743     pub fn parse_record_struct_body(&mut self,
4744                                     class_name: &ast::Ident) -> PResult<Vec<StructField>> {
4745         let mut fields = Vec::new();
4746         if try!(self.eat(&token::OpenDelim(token::Brace)) ){
4747             while self.token != token::CloseDelim(token::Brace) {
4748                 fields.push(try!(self.parse_struct_decl_field(true)));
4749             }
4750
4751             if fields.is_empty() {
4752                 return Err(self.fatal(&format!("unit-like struct definition should be \
4753                     written as `struct {};`",
4754                     class_name)));
4755             }
4756
4757             try!(self.bump());
4758         } else {
4759             let token_str = self.this_token_to_string();
4760             return Err(self.fatal(&format!("expected `where`, or `{{` after struct \
4761                                 name, found `{}`",
4762                                 token_str)));
4763         }
4764
4765         Ok(fields)
4766     }
4767
4768     pub fn parse_tuple_struct_body(&mut self,
4769                                    class_name: &ast::Ident,
4770                                    generics: &mut ast::Generics)
4771                                    -> PResult<Vec<StructField>> {
4772         // This is the case where we find `struct Foo<T>(T) where T: Copy;`
4773         // Unit like structs are handled in parse_item_struct function
4774         let fields = try!(self.parse_unspanned_seq(
4775             &token::OpenDelim(token::Paren),
4776             &token::CloseDelim(token::Paren),
4777             seq_sep_trailing_allowed(token::Comma),
4778             |p| {
4779                 let attrs = p.parse_outer_attributes();
4780                 let lo = p.span.lo;
4781                 let struct_field_ = ast::StructField_ {
4782                     kind: UnnamedField(try!(p.parse_visibility())),
4783                     id: ast::DUMMY_NODE_ID,
4784                     ty: try!(p.parse_ty_sum()),
4785                     attrs: attrs,
4786                 };
4787                 Ok(spanned(lo, p.span.hi, struct_field_))
4788             }));
4789
4790         if fields.is_empty() {
4791             return Err(self.fatal(&format!("unit-like struct definition should be \
4792                                             written as `struct {};`",
4793                                            class_name)));
4794         }
4795
4796         generics.where_clause = try!(self.parse_where_clause());
4797         try!(self.expect(&token::Semi));
4798         Ok(fields)
4799     }
4800
4801     /// Parse a structure field declaration
4802     pub fn parse_single_struct_field(&mut self,
4803                                      vis: Visibility,
4804                                      attrs: Vec<Attribute> )
4805                                      -> PResult<StructField> {
4806         let a_var = try!(self.parse_name_and_ty(vis, attrs));
4807         match self.token {
4808             token::Comma => {
4809                 try!(self.bump());
4810             }
4811             token::CloseDelim(token::Brace) => {}
4812             _ => {
4813                 let span = self.span;
4814                 let token_str = self.this_token_to_string();
4815                 return Err(self.span_fatal_help(span,
4816                                      &format!("expected `,`, or `}}`, found `{}`",
4817                                              token_str),
4818                                      "struct fields should be separated by commas"))
4819             }
4820         }
4821         Ok(a_var)
4822     }
4823
4824     /// Parse an element of a struct definition
4825     fn parse_struct_decl_field(&mut self, allow_pub: bool) -> PResult<StructField> {
4826
4827         let attrs = self.parse_outer_attributes();
4828
4829         if try!(self.eat_keyword(keywords::Pub) ){
4830             if !allow_pub {
4831                 let span = self.last_span;
4832                 self.span_err(span, "`pub` is not allowed here");
4833             }
4834             return self.parse_single_struct_field(Public, attrs);
4835         }
4836
4837         return self.parse_single_struct_field(Inherited, attrs);
4838     }
4839
4840     /// Parse visibility: PUB or nothing
4841     fn parse_visibility(&mut self) -> PResult<Visibility> {
4842         if try!(self.eat_keyword(keywords::Pub)) { Ok(Public) }
4843         else { Ok(Inherited) }
4844     }
4845
4846     /// Given a termination token, parse all of the items in a module
4847     fn parse_mod_items(&mut self, term: &token::Token, inner_lo: BytePos) -> PResult<Mod> {
4848         let mut items = vec![];
4849         while let Some(item) = try!(self.parse_item_nopanic()) {
4850             items.push(item);
4851         }
4852
4853         if !try!(self.eat(term)) {
4854             let token_str = self.this_token_to_string();
4855             return Err(self.fatal(&format!("expected item, found `{}`", token_str)));
4856         }
4857
4858         let hi = if self.span == codemap::DUMMY_SP {
4859             inner_lo
4860         } else {
4861             self.span.lo
4862         };
4863
4864         Ok(ast::Mod {
4865             inner: mk_sp(inner_lo, hi),
4866             items: items
4867         })
4868     }
4869
4870     fn parse_item_const(&mut self, m: Option<Mutability>) -> PResult<ItemInfo> {
4871         let id = try!(self.parse_ident());
4872         try!(self.expect(&token::Colon));
4873         let ty = try!(self.parse_ty_sum());
4874         try!(self.expect(&token::Eq));
4875         let e = try!(self.parse_expr_nopanic());
4876         try!(self.commit_expr_expecting(&*e, token::Semi));
4877         let item = match m {
4878             Some(m) => ItemStatic(ty, m, e),
4879             None => ItemConst(ty, e),
4880         };
4881         Ok((id, item, None))
4882     }
4883
4884     /// Parse a `mod <foo> { ... }` or `mod <foo>;` item
4885     fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<ItemInfo> {
4886         let id_span = self.span;
4887         let id = try!(self.parse_ident());
4888         if self.check(&token::Semi) {
4889             try!(self.bump());
4890             // This mod is in an external file. Let's go get it!
4891             let (m, attrs) = try!(self.eval_src_mod(id, outer_attrs, id_span));
4892             Ok((id, m, Some(attrs)))
4893         } else {
4894             self.push_mod_path(id, outer_attrs);
4895             try!(self.expect(&token::OpenDelim(token::Brace)));
4896             let mod_inner_lo = self.span.lo;
4897             let old_owns_directory = self.owns_directory;
4898             self.owns_directory = true;
4899             let attrs = self.parse_inner_attributes();
4900             let m = try!(self.parse_mod_items(&token::CloseDelim(token::Brace), mod_inner_lo));
4901             self.owns_directory = old_owns_directory;
4902             self.pop_mod_path();
4903             Ok((id, ItemMod(m), Some(attrs)))
4904         }
4905     }
4906
4907     fn push_mod_path(&mut self, id: Ident, attrs: &[Attribute]) {
4908         let default_path = self.id_to_interned_str(id);
4909         let file_path = match ::attr::first_attr_value_str_by_name(attrs, "path") {
4910             Some(d) => d,
4911             None => default_path,
4912         };
4913         self.mod_path_stack.push(file_path)
4914     }
4915
4916     fn pop_mod_path(&mut self) {
4917         self.mod_path_stack.pop().unwrap();
4918     }
4919
4920     pub fn submod_path_from_attr(attrs: &[ast::Attribute], dir_path: &Path) -> Option<PathBuf> {
4921         ::attr::first_attr_value_str_by_name(attrs, "path").map(|d| dir_path.join(&*d))
4922     }
4923
4924     /// Returns either a path to a module, or .
4925     pub fn default_submod_path(id: ast::Ident, dir_path: &Path, codemap: &CodeMap) -> ModulePath
4926     {
4927         let mod_name = id.to_string();
4928         let default_path_str = format!("{}.rs", mod_name);
4929         let secondary_path_str = format!("{}/mod.rs", mod_name);
4930         let default_path = dir_path.join(&default_path_str);
4931         let secondary_path = dir_path.join(&secondary_path_str);
4932         let default_exists = codemap.file_exists(&default_path);
4933         let secondary_exists = codemap.file_exists(&secondary_path);
4934
4935         let result = match (default_exists, secondary_exists) {
4936             (true, false) => Ok(ModulePathSuccess { path: default_path, owns_directory: false }),
4937             (false, true) => Ok(ModulePathSuccess { path: secondary_path, owns_directory: true }),
4938             (false, false) => Err(ModulePathError {
4939                 err_msg: format!("file not found for module `{}`", mod_name),
4940                 help_msg: format!("name the file either {} or {} inside the directory {:?}",
4941                                   default_path_str,
4942                                   secondary_path_str,
4943                                   dir_path.display()),
4944             }),
4945             (true, true) => Err(ModulePathError {
4946                 err_msg: format!("file for module `{}` found at both {} and {}",
4947                                  mod_name,
4948                                  default_path_str,
4949                                  secondary_path_str),
4950                 help_msg: "delete or rename one of them to remove the ambiguity".to_owned(),
4951             }),
4952         };
4953
4954         ModulePath {
4955             name: mod_name,
4956             path_exists: default_exists || secondary_exists,
4957             result: result,
4958         }
4959     }
4960
4961     fn submod_path(&mut self,
4962                    id: ast::Ident,
4963                    outer_attrs: &[ast::Attribute],
4964                    id_sp: Span) -> PResult<ModulePathSuccess> {
4965         let mut prefix = PathBuf::from(&self.sess.codemap().span_to_filename(self.span));
4966         prefix.pop();
4967         let mut dir_path = prefix;
4968         for part in &self.mod_path_stack {
4969             dir_path.push(&**part);
4970         }
4971
4972         if let Some(p) = Parser::submod_path_from_attr(outer_attrs, &dir_path) {
4973             return Ok(ModulePathSuccess { path: p, owns_directory: true });
4974         }
4975
4976         let paths = Parser::default_submod_path(id, &dir_path, self.sess.codemap());
4977
4978         if !self.owns_directory {
4979             self.span_err(id_sp, "cannot declare a new module at this location");
4980             let this_module = match self.mod_path_stack.last() {
4981                 Some(name) => name.to_string(),
4982                 None => self.root_module_name.as_ref().unwrap().clone(),
4983             };
4984             self.span_note(id_sp,
4985                            &format!("maybe move this module `{0}` to its own directory \
4986                                      via `{0}/mod.rs`",
4987                                     this_module));
4988             if paths.path_exists {
4989                 self.span_note(id_sp,
4990                                &format!("... or maybe `use` the module `{}` instead \
4991                                          of possibly redeclaring it",
4992                                         paths.name));
4993             }
4994             self.abort_if_errors();
4995         }
4996
4997         match paths.result {
4998             Ok(succ) => Ok(succ),
4999             Err(err) => Err(self.span_fatal_help(id_sp, &err.err_msg, &err.help_msg)),
5000         }
5001     }
5002
5003     /// Read a module from a source file.
5004     fn eval_src_mod(&mut self,
5005                     id: ast::Ident,
5006                     outer_attrs: &[ast::Attribute],
5007                     id_sp: Span)
5008                     -> PResult<(ast::Item_, Vec<ast::Attribute> )> {
5009         let ModulePathSuccess { path, owns_directory } = try!(self.submod_path(id,
5010                                                                                outer_attrs,
5011                                                                                id_sp));
5012
5013         self.eval_src_mod_from_path(path,
5014                                     owns_directory,
5015                                     id.to_string(),
5016                                     id_sp)
5017     }
5018
5019     fn eval_src_mod_from_path(&mut self,
5020                               path: PathBuf,
5021                               owns_directory: bool,
5022                               name: String,
5023                               id_sp: Span) -> PResult<(ast::Item_, Vec<ast::Attribute> )> {
5024         let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut();
5025         match included_mod_stack.iter().position(|p| *p == path) {
5026             Some(i) => {
5027                 let mut err = String::from("circular modules: ");
5028                 let len = included_mod_stack.len();
5029                 for p in &included_mod_stack[i.. len] {
5030                     err.push_str(&p.to_string_lossy());
5031                     err.push_str(" -> ");
5032                 }
5033                 err.push_str(&path.to_string_lossy());
5034                 return Err(self.span_fatal(id_sp, &err[..]));
5035             }
5036             None => ()
5037         }
5038         included_mod_stack.push(path.clone());
5039         drop(included_mod_stack);
5040
5041         let mut p0 = new_sub_parser_from_file(self.sess,
5042                                               self.cfg.clone(),
5043                                               &path,
5044                                               owns_directory,
5045                                               Some(name),
5046                                               id_sp);
5047         let mod_inner_lo = p0.span.lo;
5048         let mod_attrs = p0.parse_inner_attributes();
5049         let m0 = try!(p0.parse_mod_items(&token::Eof, mod_inner_lo));
5050         self.sess.included_mod_stack.borrow_mut().pop();
5051         Ok((ast::ItemMod(m0), mod_attrs))
5052     }
5053
5054     /// Parse a function declaration from a foreign module
5055     fn parse_item_foreign_fn(&mut self, vis: ast::Visibility,
5056                              attrs: Vec<Attribute>) -> PResult<P<ForeignItem>> {
5057         let lo = self.span.lo;
5058         try!(self.expect_keyword(keywords::Fn));
5059
5060         let (ident, mut generics) = try!(self.parse_fn_header());
5061         let decl = try!(self.parse_fn_decl(true));
5062         generics.where_clause = try!(self.parse_where_clause());
5063         let hi = self.span.hi;
5064         try!(self.expect(&token::Semi));
5065         Ok(P(ast::ForeignItem {
5066             ident: ident,
5067             attrs: attrs,
5068             node: ForeignItemFn(decl, generics),
5069             id: ast::DUMMY_NODE_ID,
5070             span: mk_sp(lo, hi),
5071             vis: vis
5072         }))
5073     }
5074
5075     /// Parse a static item from a foreign module
5076     fn parse_item_foreign_static(&mut self, vis: ast::Visibility,
5077                                  attrs: Vec<Attribute>) -> PResult<P<ForeignItem>> {
5078         let lo = self.span.lo;
5079
5080         try!(self.expect_keyword(keywords::Static));
5081         let mutbl = try!(self.eat_keyword(keywords::Mut));
5082
5083         let ident = try!(self.parse_ident());
5084         try!(self.expect(&token::Colon));
5085         let ty = try!(self.parse_ty_sum());
5086         let hi = self.span.hi;
5087         try!(self.expect(&token::Semi));
5088         Ok(P(ForeignItem {
5089             ident: ident,
5090             attrs: attrs,
5091             node: ForeignItemStatic(ty, mutbl),
5092             id: ast::DUMMY_NODE_ID,
5093             span: mk_sp(lo, hi),
5094             vis: vis
5095         }))
5096     }
5097
5098     /// Parse extern crate links
5099     ///
5100     /// # Examples
5101     ///
5102     /// extern crate foo;
5103     /// extern crate bar as foo;
5104     fn parse_item_extern_crate(&mut self,
5105                                lo: BytePos,
5106                                visibility: Visibility,
5107                                attrs: Vec<Attribute>)
5108                                 -> PResult<P<Item>> {
5109
5110         let crate_name = try!(self.parse_ident());
5111         let (maybe_path, ident) = if let Some(ident) = try!(self.parse_rename()) {
5112             (Some(crate_name.name), ident)
5113         } else {
5114             (None, crate_name)
5115         };
5116         try!(self.expect(&token::Semi));
5117
5118         let last_span = self.last_span;
5119         Ok(self.mk_item(lo,
5120                      last_span.hi,
5121                      ident,
5122                      ItemExternCrate(maybe_path),
5123                      visibility,
5124                      attrs))
5125     }
5126
5127     /// Parse `extern` for foreign ABIs
5128     /// modules.
5129     ///
5130     /// `extern` is expected to have been
5131     /// consumed before calling this method
5132     ///
5133     /// # Examples:
5134     ///
5135     /// extern "C" {}
5136     /// extern {}
5137     fn parse_item_foreign_mod(&mut self,
5138                               lo: BytePos,
5139                               opt_abi: Option<abi::Abi>,
5140                               visibility: Visibility,
5141                               mut attrs: Vec<Attribute>)
5142                               -> PResult<P<Item>> {
5143         try!(self.expect(&token::OpenDelim(token::Brace)));
5144
5145         let abi = opt_abi.unwrap_or(abi::C);
5146
5147         attrs.extend(self.parse_inner_attributes());
5148
5149         let mut foreign_items = vec![];
5150         while let Some(item) = try!(self.parse_foreign_item()) {
5151             foreign_items.push(item);
5152         }
5153         try!(self.expect(&token::CloseDelim(token::Brace)));
5154
5155         let last_span = self.last_span;
5156         let m = ast::ForeignMod {
5157             abi: abi,
5158             items: foreign_items
5159         };
5160         Ok(self.mk_item(lo,
5161                      last_span.hi,
5162                      special_idents::invalid,
5163                      ItemForeignMod(m),
5164                      visibility,
5165                      attrs))
5166     }
5167
5168     /// Parse type Foo = Bar;
5169     fn parse_item_type(&mut self) -> PResult<ItemInfo> {
5170         let ident = try!(self.parse_ident());
5171         let mut tps = try!(self.parse_generics());
5172         tps.where_clause = try!(self.parse_where_clause());
5173         try!(self.expect(&token::Eq));
5174         let ty = try!(self.parse_ty_sum());
5175         try!(self.expect(&token::Semi));
5176         Ok((ident, ItemTy(ty, tps), None))
5177     }
5178
5179     /// Parse a structure-like enum variant definition
5180     /// this should probably be renamed or refactored...
5181     fn parse_struct_def(&mut self) -> PResult<P<StructDef>> {
5182         let mut fields: Vec<StructField> = Vec::new();
5183         while self.token != token::CloseDelim(token::Brace) {
5184             fields.push(try!(self.parse_struct_decl_field(false)));
5185         }
5186         try!(self.bump());
5187
5188         Ok(P(StructDef {
5189             fields: fields,
5190             ctor_id: None,
5191         }))
5192     }
5193
5194     /// Parse the part of an "enum" decl following the '{'
5195     fn parse_enum_def(&mut self, _generics: &ast::Generics) -> PResult<EnumDef> {
5196         let mut variants = Vec::new();
5197         let mut all_nullary = true;
5198         let mut any_disr = None;
5199         while self.token != token::CloseDelim(token::Brace) {
5200             let variant_attrs = self.parse_outer_attributes();
5201             let vlo = self.span.lo;
5202
5203             let vis = try!(self.parse_visibility());
5204
5205             let ident;
5206             let kind;
5207             let mut args = Vec::new();
5208             let mut disr_expr = None;
5209             ident = try!(self.parse_ident());
5210             if try!(self.eat(&token::OpenDelim(token::Brace)) ){
5211                 // Parse a struct variant.
5212                 all_nullary = false;
5213                 let start_span = self.span;
5214                 let struct_def = try!(self.parse_struct_def());
5215                 if struct_def.fields.is_empty() {
5216                     self.span_err(start_span,
5217                         &format!("unit-like struct variant should be written \
5218                                  without braces, as `{},`",
5219                                 ident));
5220                 }
5221                 kind = StructVariantKind(struct_def);
5222             } else if self.check(&token::OpenDelim(token::Paren)) {
5223                 all_nullary = false;
5224                 let arg_tys = try!(self.parse_enum_variant_seq(
5225                     &token::OpenDelim(token::Paren),
5226                     &token::CloseDelim(token::Paren),
5227                     seq_sep_trailing_allowed(token::Comma),
5228                     |p| p.parse_ty_sum()
5229                 ));
5230                 for ty in arg_tys {
5231                     args.push(ast::VariantArg {
5232                         ty: ty,
5233                         id: ast::DUMMY_NODE_ID,
5234                     });
5235                 }
5236                 kind = TupleVariantKind(args);
5237             } else if try!(self.eat(&token::Eq) ){
5238                 disr_expr = Some(try!(self.parse_expr_nopanic()));
5239                 any_disr = disr_expr.as_ref().map(|expr| expr.span);
5240                 kind = TupleVariantKind(args);
5241             } else {
5242                 kind = TupleVariantKind(Vec::new());
5243             }
5244
5245             let vr = ast::Variant_ {
5246                 name: ident,
5247                 attrs: variant_attrs,
5248                 kind: kind,
5249                 id: ast::DUMMY_NODE_ID,
5250                 disr_expr: disr_expr,
5251                 vis: vis,
5252             };
5253             variants.push(P(spanned(vlo, self.last_span.hi, vr)));
5254
5255             if !try!(self.eat(&token::Comma)) { break; }
5256         }
5257         try!(self.expect(&token::CloseDelim(token::Brace)));
5258         match any_disr {
5259             Some(disr_span) if !all_nullary =>
5260                 self.span_err(disr_span,
5261                     "discriminator values can only be used with a c-like enum"),
5262             _ => ()
5263         }
5264
5265         Ok(ast::EnumDef { variants: variants })
5266     }
5267
5268     /// Parse an "enum" declaration
5269     fn parse_item_enum(&mut self) -> PResult<ItemInfo> {
5270         let id = try!(self.parse_ident());
5271         let mut generics = try!(self.parse_generics());
5272         generics.where_clause = try!(self.parse_where_clause());
5273         try!(self.expect(&token::OpenDelim(token::Brace)));
5274
5275         let enum_definition = try!(self.parse_enum_def(&generics));
5276         Ok((id, ItemEnum(enum_definition, generics), None))
5277     }
5278
5279     /// Parses a string as an ABI spec on an extern type or module. Consumes
5280     /// the `extern` keyword, if one is found.
5281     fn parse_opt_abi(&mut self) -> PResult<Option<abi::Abi>> {
5282         match self.token {
5283             token::Literal(token::Str_(s), suf) | token::Literal(token::StrRaw(s, _), suf) => {
5284                 let sp = self.span;
5285                 self.expect_no_suffix(sp, "ABI spec", suf);
5286                 try!(self.bump());
5287                 match abi::lookup(&s.as_str()) {
5288                     Some(abi) => Ok(Some(abi)),
5289                     None => {
5290                         let last_span = self.last_span;
5291                         self.span_err(
5292                             last_span,
5293                             &format!("invalid ABI: expected one of [{}], \
5294                                      found `{}`",
5295                                     abi::all_names().join(", "),
5296                                     s));
5297                         Ok(None)
5298                     }
5299                 }
5300             }
5301
5302             _ => Ok(None),
5303         }
5304     }
5305
5306     /// Parse one of the items allowed by the flags.
5307     /// NB: this function no longer parses the items inside an
5308     /// extern crate.
5309     fn parse_item_(&mut self, attrs: Vec<Attribute>,
5310                    macros_allowed: bool) -> PResult<Option<P<Item>>> {
5311         let nt_item = match self.token {
5312             token::Interpolated(token::NtItem(ref item)) => {
5313                 Some((**item).clone())
5314             }
5315             _ => None
5316         };
5317         match nt_item {
5318             Some(mut item) => {
5319                 try!(self.bump());
5320                 let mut attrs = attrs;
5321                 mem::swap(&mut item.attrs, &mut attrs);
5322                 item.attrs.extend(attrs);
5323                 return Ok(Some(P(item)));
5324             }
5325             None => {}
5326         }
5327
5328         let lo = self.span.lo;
5329
5330         let visibility = try!(self.parse_visibility());
5331
5332         if try!(self.eat_keyword(keywords::Use) ){
5333             // USE ITEM
5334             let item_ = ItemUse(try!(self.parse_view_path()));
5335             try!(self.expect(&token::Semi));
5336
5337             let last_span = self.last_span;
5338             let item = self.mk_item(lo,
5339                                     last_span.hi,
5340                                     token::special_idents::invalid,
5341                                     item_,
5342                                     visibility,
5343                                     attrs);
5344             return Ok(Some(item));
5345         }
5346
5347         if try!(self.eat_keyword(keywords::Extern)) {
5348             if try!(self.eat_keyword(keywords::Crate)) {
5349                 return Ok(Some(try!(self.parse_item_extern_crate(lo, visibility, attrs))));
5350             }
5351
5352             let opt_abi = try!(self.parse_opt_abi());
5353
5354             if try!(self.eat_keyword(keywords::Fn) ){
5355                 // EXTERN FUNCTION ITEM
5356                 let abi = opt_abi.unwrap_or(abi::C);
5357                 let (ident, item_, extra_attrs) =
5358                     try!(self.parse_item_fn(Unsafety::Normal, Constness::NotConst, abi));
5359                 let last_span = self.last_span;
5360                 let item = self.mk_item(lo,
5361                                         last_span.hi,
5362                                         ident,
5363                                         item_,
5364                                         visibility,
5365                                         maybe_append(attrs, extra_attrs));
5366                 return Ok(Some(item));
5367             } else if self.check(&token::OpenDelim(token::Brace)) {
5368                 return Ok(Some(try!(self.parse_item_foreign_mod(lo, opt_abi, visibility, attrs))));
5369             }
5370
5371             try!(self.expect_one_of(&[], &[]));
5372         }
5373
5374         if try!(self.eat_keyword(keywords::Static) ){
5375             // STATIC ITEM
5376             let m = if try!(self.eat_keyword(keywords::Mut)) {MutMutable} else {MutImmutable};
5377             let (ident, item_, extra_attrs) = try!(self.parse_item_const(Some(m)));
5378             let last_span = self.last_span;
5379             let item = self.mk_item(lo,
5380                                     last_span.hi,
5381                                     ident,
5382                                     item_,
5383                                     visibility,
5384                                     maybe_append(attrs, extra_attrs));
5385             return Ok(Some(item));
5386         }
5387         if try!(self.eat_keyword(keywords::Const) ){
5388             if self.check_keyword(keywords::Fn) {
5389                 // CONST FUNCTION ITEM
5390                 try!(self.bump());
5391                 let (ident, item_, extra_attrs) =
5392                     try!(self.parse_item_fn(Unsafety::Normal, Constness::Const, abi::Rust));
5393                 let last_span = self.last_span;
5394                 let item = self.mk_item(lo,
5395                                         last_span.hi,
5396                                         ident,
5397                                         item_,
5398                                         visibility,
5399                                         maybe_append(attrs, extra_attrs));
5400                 return Ok(Some(item));
5401             }
5402
5403             // CONST ITEM
5404             if try!(self.eat_keyword(keywords::Mut) ){
5405                 let last_span = self.last_span;
5406                 self.span_err(last_span, "const globals cannot be mutable");
5407                 self.fileline_help(last_span, "did you mean to declare a static?");
5408             }
5409             let (ident, item_, extra_attrs) = try!(self.parse_item_const(None));
5410             let last_span = self.last_span;
5411             let item = self.mk_item(lo,
5412                                     last_span.hi,
5413                                     ident,
5414                                     item_,
5415                                     visibility,
5416                                     maybe_append(attrs, extra_attrs));
5417             return Ok(Some(item));
5418         }
5419         if self.check_keyword(keywords::Unsafe) &&
5420             self.look_ahead(1, |t| t.is_keyword(keywords::Trait))
5421         {
5422             // UNSAFE TRAIT ITEM
5423             try!(self.expect_keyword(keywords::Unsafe));
5424             try!(self.expect_keyword(keywords::Trait));
5425             let (ident, item_, extra_attrs) =
5426                 try!(self.parse_item_trait(ast::Unsafety::Unsafe));
5427             let last_span = self.last_span;
5428             let item = self.mk_item(lo,
5429                                     last_span.hi,
5430                                     ident,
5431                                     item_,
5432                                     visibility,
5433                                     maybe_append(attrs, extra_attrs));
5434             return Ok(Some(item));
5435         }
5436         if self.check_keyword(keywords::Unsafe) &&
5437             self.look_ahead(1, |t| t.is_keyword(keywords::Impl))
5438         {
5439             // IMPL ITEM
5440             try!(self.expect_keyword(keywords::Unsafe));
5441             try!(self.expect_keyword(keywords::Impl));
5442             let (ident, item_, extra_attrs) = try!(self.parse_item_impl(ast::Unsafety::Unsafe));
5443             let last_span = self.last_span;
5444             let item = self.mk_item(lo,
5445                                     last_span.hi,
5446                                     ident,
5447                                     item_,
5448                                     visibility,
5449                                     maybe_append(attrs, extra_attrs));
5450             return Ok(Some(item));
5451         }
5452         if self.check_keyword(keywords::Fn) {
5453             // FUNCTION ITEM
5454             try!(self.bump());
5455             let (ident, item_, extra_attrs) =
5456                 try!(self.parse_item_fn(Unsafety::Normal, Constness::NotConst, abi::Rust));
5457             let last_span = self.last_span;
5458             let item = self.mk_item(lo,
5459                                     last_span.hi,
5460                                     ident,
5461                                     item_,
5462                                     visibility,
5463                                     maybe_append(attrs, extra_attrs));
5464             return Ok(Some(item));
5465         }
5466         if self.check_keyword(keywords::Unsafe)
5467             && self.look_ahead(1, |t| *t != token::OpenDelim(token::Brace)) {
5468             // UNSAFE FUNCTION ITEM
5469             try!(self.bump());
5470             let abi = if try!(self.eat_keyword(keywords::Extern) ){
5471                 try!(self.parse_opt_abi()).unwrap_or(abi::C)
5472             } else {
5473                 abi::Rust
5474             };
5475             try!(self.expect_keyword(keywords::Fn));
5476             let (ident, item_, extra_attrs) =
5477                 try!(self.parse_item_fn(Unsafety::Unsafe, Constness::NotConst, abi));
5478             let last_span = self.last_span;
5479             let item = self.mk_item(lo,
5480                                     last_span.hi,
5481                                     ident,
5482                                     item_,
5483                                     visibility,
5484                                     maybe_append(attrs, extra_attrs));
5485             return Ok(Some(item));
5486         }
5487         if try!(self.eat_keyword(keywords::Mod) ){
5488             // MODULE ITEM
5489             let (ident, item_, extra_attrs) =
5490                 try!(self.parse_item_mod(&attrs[..]));
5491             let last_span = self.last_span;
5492             let item = self.mk_item(lo,
5493                                     last_span.hi,
5494                                     ident,
5495                                     item_,
5496                                     visibility,
5497                                     maybe_append(attrs, extra_attrs));
5498             return Ok(Some(item));
5499         }
5500         if try!(self.eat_keyword(keywords::Type) ){
5501             // TYPE ITEM
5502             let (ident, item_, extra_attrs) = try!(self.parse_item_type());
5503             let last_span = self.last_span;
5504             let item = self.mk_item(lo,
5505                                     last_span.hi,
5506                                     ident,
5507                                     item_,
5508                                     visibility,
5509                                     maybe_append(attrs, extra_attrs));
5510             return Ok(Some(item));
5511         }
5512         if try!(self.eat_keyword(keywords::Enum) ){
5513             // ENUM ITEM
5514             let (ident, item_, extra_attrs) = try!(self.parse_item_enum());
5515             let last_span = self.last_span;
5516             let item = self.mk_item(lo,
5517                                     last_span.hi,
5518                                     ident,
5519                                     item_,
5520                                     visibility,
5521                                     maybe_append(attrs, extra_attrs));
5522             return Ok(Some(item));
5523         }
5524         if try!(self.eat_keyword(keywords::Trait) ){
5525             // TRAIT ITEM
5526             let (ident, item_, extra_attrs) =
5527                 try!(self.parse_item_trait(ast::Unsafety::Normal));
5528             let last_span = self.last_span;
5529             let item = self.mk_item(lo,
5530                                     last_span.hi,
5531                                     ident,
5532                                     item_,
5533                                     visibility,
5534                                     maybe_append(attrs, extra_attrs));
5535             return Ok(Some(item));
5536         }
5537         if try!(self.eat_keyword(keywords::Impl) ){
5538             // IMPL ITEM
5539             let (ident, item_, extra_attrs) = try!(self.parse_item_impl(ast::Unsafety::Normal));
5540             let last_span = self.last_span;
5541             let item = self.mk_item(lo,
5542                                     last_span.hi,
5543                                     ident,
5544                                     item_,
5545                                     visibility,
5546                                     maybe_append(attrs, extra_attrs));
5547             return Ok(Some(item));
5548         }
5549         if try!(self.eat_keyword(keywords::Struct) ){
5550             // STRUCT ITEM
5551             let (ident, item_, extra_attrs) = try!(self.parse_item_struct());
5552             let last_span = self.last_span;
5553             let item = self.mk_item(lo,
5554                                     last_span.hi,
5555                                     ident,
5556                                     item_,
5557                                     visibility,
5558                                     maybe_append(attrs, extra_attrs));
5559             return Ok(Some(item));
5560         }
5561         self.parse_macro_use_or_failure(attrs,macros_allowed,lo,visibility)
5562     }
5563
5564     /// Parse a foreign item.
5565     fn parse_foreign_item(&mut self) -> PResult<Option<P<ForeignItem>>> {
5566         let attrs = self.parse_outer_attributes();
5567         let lo = self.span.lo;
5568         let visibility = try!(self.parse_visibility());
5569
5570         if self.check_keyword(keywords::Static) {
5571             // FOREIGN STATIC ITEM
5572             return Ok(Some(try!(self.parse_item_foreign_static(visibility, attrs))));
5573         }
5574         if self.check_keyword(keywords::Fn) || self.check_keyword(keywords::Unsafe) {
5575             // FOREIGN FUNCTION ITEM
5576             return Ok(Some(try!(self.parse_item_foreign_fn(visibility, attrs))));
5577         }
5578
5579         // FIXME #5668: this will occur for a macro invocation:
5580         match try!(self.parse_macro_use_or_failure(attrs, true, lo, visibility)) {
5581             Some(item) => {
5582                 return Err(self.span_fatal(item.span, "macros cannot expand to foreign items"));
5583             }
5584             None => Ok(None)
5585         }
5586     }
5587
5588     /// This is the fall-through for parsing items.
5589     fn parse_macro_use_or_failure(
5590         &mut self,
5591         attrs: Vec<Attribute> ,
5592         macros_allowed: bool,
5593         lo: BytePos,
5594         visibility: Visibility
5595     ) -> PResult<Option<P<Item>>> {
5596         if macros_allowed && !self.token.is_any_keyword()
5597                 && self.look_ahead(1, |t| *t == token::Not)
5598                 && (self.look_ahead(2, |t| t.is_plain_ident())
5599                     || self.look_ahead(2, |t| *t == token::OpenDelim(token::Paren))
5600                     || self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace))) {
5601             // MACRO INVOCATION ITEM
5602
5603             let last_span = self.last_span;
5604             self.complain_if_pub_macro(visibility, last_span);
5605
5606             // item macro.
5607             let pth = try!(self.parse_path(NoTypesAllowed));
5608             try!(self.expect(&token::Not));
5609
5610             // a 'special' identifier (like what `macro_rules!` uses)
5611             // is optional. We should eventually unify invoc syntax
5612             // and remove this.
5613             let id = if self.token.is_plain_ident() {
5614                 try!(self.parse_ident())
5615             } else {
5616                 token::special_idents::invalid // no special identifier
5617             };
5618             // eat a matched-delimiter token tree:
5619             let delim = try!(self.expect_open_delim());
5620             let tts = try!(self.parse_seq_to_end(&token::CloseDelim(delim),
5621                                             seq_sep_none(),
5622                                             |p| p.parse_token_tree()));
5623             // single-variant-enum... :
5624             let m = ast::MacInvocTT(pth, tts, EMPTY_CTXT);
5625             let m: ast::Mac = codemap::Spanned { node: m,
5626                                              span: mk_sp(self.span.lo,
5627                                                          self.span.hi) };
5628
5629             if delim != token::Brace {
5630                 if !try!(self.eat(&token::Semi) ){
5631                     let last_span = self.last_span;
5632                     self.span_err(last_span,
5633                                   "macros that expand to items must either \
5634                                    be surrounded with braces or followed by \
5635                                    a semicolon");
5636                 }
5637             }
5638
5639             let item_ = ItemMac(m);
5640             let last_span = self.last_span;
5641             let item = self.mk_item(lo,
5642                                     last_span.hi,
5643                                     id,
5644                                     item_,
5645                                     visibility,
5646                                     attrs);
5647             return Ok(Some(item));
5648         }
5649
5650         // FAILURE TO PARSE ITEM
5651         match visibility {
5652             Inherited => {}
5653             Public => {
5654                 let last_span = self.last_span;
5655                 return Err(self.span_fatal(last_span, "unmatched visibility `pub`"));
5656             }
5657         }
5658
5659         if !attrs.is_empty() {
5660             self.expected_item_err(&attrs);
5661         }
5662         Ok(None)
5663     }
5664
5665     pub fn parse_item_nopanic(&mut self) -> PResult<Option<P<Item>>> {
5666         let attrs = self.parse_outer_attributes();
5667         self.parse_item_(attrs, true)
5668     }
5669
5670
5671     /// Matches view_path : MOD? non_global_path as IDENT
5672     /// | MOD? non_global_path MOD_SEP LBRACE RBRACE
5673     /// | MOD? non_global_path MOD_SEP LBRACE ident_seq RBRACE
5674     /// | MOD? non_global_path MOD_SEP STAR
5675     /// | MOD? non_global_path
5676     fn parse_view_path(&mut self) -> PResult<P<ViewPath>> {
5677         let lo = self.span.lo;
5678
5679         // Allow a leading :: because the paths are absolute either way.
5680         // This occurs with "use $crate::..." in macros.
5681         try!(self.eat(&token::ModSep));
5682
5683         if self.check(&token::OpenDelim(token::Brace)) {
5684             // use {foo,bar}
5685             let idents = try!(self.parse_unspanned_seq(
5686                 &token::OpenDelim(token::Brace),
5687                 &token::CloseDelim(token::Brace),
5688                 seq_sep_trailing_allowed(token::Comma),
5689                 |p| p.parse_path_list_item()));
5690             let path = ast::Path {
5691                 span: mk_sp(lo, self.span.hi),
5692                 global: false,
5693                 segments: Vec::new()
5694             };
5695             return Ok(P(spanned(lo, self.span.hi, ViewPathList(path, idents))));
5696         }
5697
5698         let first_ident = try!(self.parse_ident());
5699         let mut path = vec!(first_ident);
5700         if let token::ModSep = self.token {
5701             // foo::bar or foo::{a,b,c} or foo::*
5702             while self.check(&token::ModSep) {
5703                 try!(self.bump());
5704
5705                 match self.token {
5706                   token::Ident(..) => {
5707                     let ident = try!(self.parse_ident());
5708                     path.push(ident);
5709                   }
5710
5711                   // foo::bar::{a,b,c}
5712                   token::OpenDelim(token::Brace) => {
5713                     let idents = try!(self.parse_unspanned_seq(
5714                         &token::OpenDelim(token::Brace),
5715                         &token::CloseDelim(token::Brace),
5716                         seq_sep_trailing_allowed(token::Comma),
5717                         |p| p.parse_path_list_item()
5718                     ));
5719                     let path = ast::Path {
5720                         span: mk_sp(lo, self.span.hi),
5721                         global: false,
5722                         segments: path.into_iter().map(|identifier| {
5723                             ast::PathSegment {
5724                                 identifier: identifier,
5725                                 parameters: ast::PathParameters::none(),
5726                             }
5727                         }).collect()
5728                     };
5729                     return Ok(P(spanned(lo, self.span.hi, ViewPathList(path, idents))));
5730                   }
5731
5732                   // foo::bar::*
5733                   token::BinOp(token::Star) => {
5734                     try!(self.bump());
5735                     let path = ast::Path {
5736                         span: mk_sp(lo, self.span.hi),
5737                         global: false,
5738                         segments: path.into_iter().map(|identifier| {
5739                             ast::PathSegment {
5740                                 identifier: identifier,
5741                                 parameters: ast::PathParameters::none(),
5742                             }
5743                         }).collect()
5744                     };
5745                     return Ok(P(spanned(lo, self.span.hi, ViewPathGlob(path))));
5746                   }
5747
5748                   // fall-through for case foo::bar::;
5749                   token::Semi => {
5750                     self.span_err(self.span, "expected identifier or `{` or `*`, found `;`");
5751                   }
5752
5753                   _ => break
5754                 }
5755             }
5756         }
5757         let mut rename_to = path[path.len() - 1];
5758         let path = ast::Path {
5759             span: mk_sp(lo, self.last_span.hi),
5760             global: false,
5761             segments: path.into_iter().map(|identifier| {
5762                 ast::PathSegment {
5763                     identifier: identifier,
5764                     parameters: ast::PathParameters::none(),
5765                 }
5766             }).collect()
5767         };
5768         rename_to = try!(self.parse_rename()).unwrap_or(rename_to);
5769         Ok(P(spanned(lo, self.last_span.hi, ViewPathSimple(rename_to, path))))
5770     }
5771
5772     fn parse_rename(&mut self) -> PResult<Option<Ident>> {
5773         if try!(self.eat_keyword(keywords::As)) {
5774             self.parse_ident().map(Some)
5775         } else {
5776             Ok(None)
5777         }
5778     }
5779
5780     /// Parses a source module as a crate. This is the main
5781     /// entry point for the parser.
5782     pub fn parse_crate_mod(&mut self) -> PResult<Crate> {
5783         let lo = self.span.lo;
5784         Ok(ast::Crate {
5785             attrs: self.parse_inner_attributes(),
5786             module: try!(self.parse_mod_items(&token::Eof, lo)),
5787             config: self.cfg.clone(),
5788             span: mk_sp(lo, self.span.lo),
5789             exported_macros: Vec::new(),
5790         })
5791     }
5792
5793     pub fn parse_optional_str(&mut self)
5794                               -> PResult<Option<(InternedString,
5795                                                  ast::StrStyle,
5796                                                  Option<ast::Name>)>> {
5797         let ret = match self.token {
5798             token::Literal(token::Str_(s), suf) => {
5799                 (self.id_to_interned_str(s.ident()), ast::CookedStr, suf)
5800             }
5801             token::Literal(token::StrRaw(s, n), suf) => {
5802                 (self.id_to_interned_str(s.ident()), ast::RawStr(n), suf)
5803             }
5804             _ => return Ok(None)
5805         };
5806         try!(self.bump());
5807         Ok(Some(ret))
5808     }
5809
5810     pub fn parse_str(&mut self) -> PResult<(InternedString, StrStyle)> {
5811         match try!(self.parse_optional_str()) {
5812             Some((s, style, suf)) => {
5813                 let sp = self.last_span;
5814                 self.expect_no_suffix(sp, "string literal", suf);
5815                 Ok((s, style))
5816             }
5817             _ =>  Err(self.fatal("expected string literal"))
5818         }
5819     }
5820 }