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.
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.
11 pub use self::PathParsingMode
::*;
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}
;
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}
;
63 use ast_util
::{self, AS_PREC, ident_to_path, operator_prec}
;
64 use codemap
::{self, Span, BytePos, Spanned, spanned, mk_sp, CodeMap}
;
66 use ext
::tt
::macro_parser
;
68 use parse
::attr
::ParserAttr
;
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}
;
78 use owned_slice
::OwnedSlice
;
80 use diagnostic
::FatalError
;
82 use std
::collections
::HashSet
;
83 use std
::io
::prelude
::*;
85 use std
::path
::{Path, PathBuf}
;
90 flags Restrictions
: u8 {
91 const RESTRICTION_STMT_EXPR
= 1 << 0,
92 const RESTRICTION_NO_STRUCT_LITERAL
= 1 << 1,
96 type ItemInfo
= (Ident
, Item_
, Option
<Vec
<Attribute
> >);
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`
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
,
112 /// How to parse a bound, whether to allow bound modifiers such as `?`.
113 #[derive(Copy, Clone, PartialEq)]
114 pub enum BoundParsingMode
{
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
{
127 let found
= match $p
.token
{
128 token
::Interpolated(token
::NtExpr(ref e
)) => {
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 $p
.token
{
135 token
::Interpolated(token
::NtPath(ref pt
)) => (**pt
).clone(),
139 Some($p
.mk_expr(span
.lo
, span
.hi
, ExprPath(None
, pt
)))
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 $p
.token
{
145 token
::Interpolated(token
::NtBlock(ref b
)) => (*b
).clone(),
149 Some($p
.mk_expr(span
.lo
, span
.hi
, ExprBlock(b
)))
164 /// As maybe_whole_expr, but for things other than expressions
165 macro_rules
! maybe_whole
{
166 ($p
:expr
, $constructor
:ident
) => (
168 let found
= match ($p
).token
{
169 token
::Interpolated(token
::$
constructor(_
)) => {
170 Some(try
!(($p
).bump_and_get()))
174 if let Some(token
::Interpolated(token
::$
constructor(x
))) = found
{
175 return Ok(x
.clone());
179 (no_clone $p
:expr
, $constructor
:ident
) => (
181 let found
= match ($p
).token
{
182 token
::Interpolated(token
::$
constructor(_
)) => {
183 Some(try
!(($p
).bump_and_get()))
187 if let Some(token
::Interpolated(token
::$
constructor(x
))) = found
{
192 (deref $p
:expr
, $constructor
:ident
) => (
194 let found
= match ($p
).token
{
195 token
::Interpolated(token
::$
constructor(_
)) => {
196 Some(try
!(($p
).bump_and_get()))
200 if let Some(token
::Interpolated(token
::$
constructor(x
))) = found
{
201 return Ok((*x
).clone());
205 (Some deref $p
:expr
, $constructor
:ident
) => (
207 let found
= match ($p
).token
{
208 token
::Interpolated(token
::$
constructor(_
)) => {
209 Some(try
!(($p
).bump_and_get()))
213 if let Some(token
::Interpolated(token
::$
constructor(x
))) = found
{
214 return Ok(Some((*x
).clone()));
218 (pair_empty $p
:expr
, $constructor
:ident
) => (
220 let found
= match ($p
).token
{
221 token
::Interpolated(token
::$
constructor(_
)) => {
222 Some(try
!(($p
).bump_and_get()))
226 if let Some(token
::Interpolated(token
::$
constructor(x
))) = found
{
227 return Ok((Vec
::new(), x
));
234 fn maybe_append(mut lhs
: Vec
<Attribute
>, rhs
: Option
<Vec
<Attribute
>>)
236 if let Some(ref attrs
) = rhs
{
237 lhs
.extend(attrs
.iter().cloned())
242 /* ident is handled by common.rs */
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:
250 /// the span of the prior token:
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
>,
280 #[derive(PartialEq, Eq, Clone)]
283 Keyword(keywords
::Keyword
),
288 fn to_string(&self) -> String
{
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()),
297 fn is_plain_ident_or_underscore(t
: &token
::Token
) -> bool
{
298 t
.is_plain_ident() || *t
== token
::Underscore
301 /// Information about the path to a module.
302 pub struct ModulePath
{
304 pub path_exists
: bool
,
305 pub result
: Result
<ModulePathSuccess
, ModulePathError
>,
308 pub struct ModulePathSuccess
{
309 pub path
: ::std
::path
::PathBuf
,
310 pub owns_directory
: bool
,
313 pub struct ModulePathError
{
315 pub help_msg
: String
,
319 impl<'a
> Parser
<'a
> {
320 pub fn new(sess
: &'a ParseSess
,
321 cfg
: ast
::CrateConfig
,
322 mut rdr
: Box
<Reader
+'a
>)
325 let tok0
= rdr
.real_token();
327 let placeholder
= TokenAndSpan
{
328 tok
: token
::Underscore
,
334 interner
: token
::get_ident_interner(),
350 restrictions
: Restrictions
::empty(),
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(),
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())
367 pub fn parse_item(&mut self) -> Option
<P
<Item
>> {
368 panictry
!(self.parse_item_nopanic())
371 pub fn parse_pat(&mut self) -> P
<Pat
> {
372 panictry
!(self.parse_pat_nopanic())
375 pub fn parse_arm(&mut self) -> Arm
{
376 panictry
!(self.parse_arm_nopanic())
379 pub fn parse_ty(&mut self) -> P
<Ty
> {
380 panictry
!(self.parse_ty_nopanic())
383 pub fn parse_stmt(&mut self) -> Option
<P
<Stmt
>> {
384 panictry
!(self.parse_stmt_nopanic())
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
)
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
)
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: `{}`",
404 pub fn unexpected(&mut self) -> FatalError
{
405 match self.expect_one_of(&[], &[]) {
407 Ok(_
) => unreachable
!()
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
{
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 `{}`",
425 self.expect_one_of(slice
::ref_slice(t
), &[])
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.
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 {
443 } else if tokens
.len() == 2 && i
== tokens
.len() - 2 {
448 b
.push_str(&*a
.to_string());
452 if edible
.contains(&self.token
) {
454 } else if inedible
.contains(&self.token
) {
455 // leave it in the input
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()));
465 let expect
= tokens_to_string(&expected
[..]);
466 let actual
= self.this_token_to_string();
468 &(if expected
.len() > 1 {
469 (format
!("expected one of {}, found `{}`",
472 } else if expected
.is_empty() {
473 (format
!("unexpected token: `{}`",
476 (format
!("expected {}, found `{}`",
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
])
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
;
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
)));
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()
515 .chain(inedible
.iter().cloned())
516 .collect
::<Vec
<_
>>();
517 try
!(self.check_for_erroneous_unit_struct_expecting(&expected
[..]));
519 self.expect_one_of(edible
, inedible
)
522 pub fn commit_expr_expecting(&mut self, e
: &Expr
, edible
: token
::Token
) -> PResult
<()> {
523 self.commit_expr(e
, &[edible
], &[])
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
<()> {
533 .map_or(false, |t
| t
.is_ident() || t
.is_path()) {
534 let expected
= edible
.iter()
536 .chain(inedible
.iter().cloned())
537 .collect
::<Vec
<_
>>();
538 try
!(self.check_for_erroneous_unit_struct_expecting(&expected
));
540 self.expect_one_of(edible
, inedible
)
543 pub fn commit_stmt_expecting(&mut self, edible
: token
::Token
) -> PResult
<()> {
544 self.commit_stmt(&[edible
], &[])
547 pub fn parse_ident(&mut self) -> PResult
<ast
::Ident
> {
548 self.check_strict_keywords();
549 try
!(self.check_reserved_keywords());
551 token
::Ident(i
, _
) => {
555 token
::Interpolated(token
::NtIdent(..)) => {
556 self.bug("ident interpolation not converted to real token");
559 let token_str
= self.this_token_to_string();
560 Err(self.fatal(&format
!("expected ident, found `{}`",
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()
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 }
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 }
584 let hi
= self.last_span
.hi
;
585 Ok(spanned(lo
, hi
, node
))
588 /// Check if the next token is `tok`, and return `true` if so.
590 /// This method is will automatically add `tok` to `expected_tokens` if `tok` is not
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())); }
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())}
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
)
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
) {
622 pub fn eat_keyword_noexpect(&mut self, kw
: keywords
::Keyword
) -> PResult
<bool
> {
623 if self.token
.is_keyword(kw
) {
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(&[], &[])
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
;
648 &format
!("expected identifier, found keyword `{}`",
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",
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
)));
669 token
::BinOp(token
::And
) => self.bump(),
671 let span
= self.span
;
672 let lo
= span
.lo
+ BytePos(1);
673 Ok(self.replace_token(token
::BinOp(token
::And
), lo
, span
.hi
))
675 _
=> self.expect_one_of(&[], &[])
679 pub fn expect_no_suffix(&self, sp
: Span
, kind
: &str, suffix
: Option
<ast
::Name
>) {
681 None
=> {/* everything ok */}
683 let text
= suf
.as_str();
685 self.span_bug(sp
, "found empty literal suffix in Some")
687 self.span_err(sp
, &*format
!("{} with a suffix is invalid", kind
));
693 /// Attempt to consume a `<`. If `<<` is seen, replace it with a single
694 /// `<` and continue. If a `<` is not seen, return false.
696 /// This is meant to be used when parsing generics on a path to get the
698 fn eat_lt(&mut self) -> PResult
<bool
> {
699 self.expected_tokens
.push(TokenType
::Token(token
::Lt
));
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
);
712 fn expect_lt(&mut self) -> PResult
<()> {
713 if !try
!(self.eat_lt()) {
714 self.expect_one_of(&[], &[])
720 /// Expect and consume a GT. if a >> is seen, replace it
721 /// with a single > and continue. If a GT is not seen,
723 pub fn expect_gt(&mut self) -> PResult
<()> {
724 self.expected_tokens
.push(TokenType
::Token(token
::Gt
));
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
))
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
))
738 let span
= self.span
;
739 let lo
= span
.lo
+ BytePos(1);
740 Ok(self.replace_token(token
::Eq
, lo
, span
.hi
))
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 `{}`",
752 pub fn parse_seq_to_before_gt_or_return
<T
, F
>(&mut self,
753 sep
: Option
<token
::Token
>,
755 -> PResult
<(OwnedSlice
<T
>, bool
)> where
756 F
: FnMut(&mut Parser
) -> PResult
<Option
<T
>>,
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.
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
) {
774 match try
!(f(self)) {
775 Some(result
) => v
.push(result
),
776 None
=> return Ok((OwnedSlice
::from_vec(v
), true))
779 if let Some(t
) = sep
.as_ref() {
780 try
!(self.expect(t
));
785 return Ok((OwnedSlice
::from_vec(v
), false));
788 /// Parse a sequence bracketed by '<' and '>', stopping
790 pub fn parse_seq_to_before_gt
<T
, F
>(&mut self,
791 sep
: Option
<token
::Token
>,
793 -> PResult
<OwnedSlice
<T
>> where
794 F
: FnMut(&mut Parser
) -> PResult
<T
>,
796 let (result
, returned
) = try
!(self.parse_seq_to_before_gt_or_return(sep
,
797 |p
| Ok(Some(try
!(f(p
))))));
802 pub fn parse_seq_to_gt
<T
, F
>(&mut self,
803 sep
: Option
<token
::Token
>,
805 -> PResult
<OwnedSlice
<T
>> where
806 F
: FnMut(&mut Parser
) -> PResult
<T
>,
808 let v
= try
!(self.parse_seq_to_before_gt(sep
, f
));
809 try
!(self.expect_gt());
813 pub fn parse_seq_to_gt_or_return
<T
, F
>(&mut self,
814 sep
: Option
<token
::Token
>,
816 -> PResult
<(OwnedSlice
<T
>, bool
)> where
817 F
: FnMut(&mut Parser
) -> PResult
<Option
<T
>>,
819 let (v
, returned
) = try
!(self.parse_seq_to_before_gt_or_return(sep
, f
));
821 try
!(self.expect_gt());
823 return Ok((v
, returned
));
826 /// Parse a sequence, including the closing delimiter. The function
827 /// f must consume tokens until reaching the next separator or
829 pub fn parse_seq_to_end
<T
, F
>(&mut self,
833 -> PResult
<Vec
<T
>> where
834 F
: FnMut(&mut Parser
) -> PResult
<T
>,
836 let val
= try
!(self.parse_seq_to_before_end(ket
, sep
, f
));
841 /// Parse a sequence, not including the closing delimiter. The function
842 /// f must consume tokens until reaching the next separator or
844 pub fn parse_seq_to_before_end
<T
, F
>(&mut self,
848 -> PResult
<Vec
<T
>> where
849 F
: FnMut(&mut Parser
) -> PResult
<T
>,
851 let mut first
: bool
= true;
853 while self.token
!= *ket
{
856 if first { first = false; }
857 else { try!(self.expect(t)); }
861 if sep
.trailing_sep_allowed
&& self.check(ket
) { break; }
862 v
.push(try
!(f(self)));
867 /// Parse a sequence, including the closing delimiter. The function
868 /// f must consume tokens until reaching the next separator or
870 pub fn parse_unspanned_seq
<T
, F
>(&mut self,
875 -> PResult
<Vec
<T
>> where
876 F
: FnMut(&mut Parser
) -> PResult
<T
>,
878 try
!(self.expect(bra
));
879 let result
= try
!(self.parse_seq_to_before_end(ket
, sep
, f
));
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,
891 -> PResult
<Vec
<T
>> where
892 F
: FnMut(&mut Parser
) -> PResult
<T
>,
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 `( )`");
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,
910 -> PResult
<Spanned
<Vec
<T
>>> where
911 F
: FnMut(&mut Parser
) -> PResult
<T
>,
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
;
918 Ok(spanned(lo
, hi
, result
))
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()))
932 let next
= if self.buffer_start
== self.buffer_end
{
933 self.reader
.real_token()
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;
940 let placeholder
= TokenAndSpan
{
941 tok
: token
::Underscore
,
944 mem
::replace(&mut self.buffer
[buffer_start
], placeholder
)
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()
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
);
961 /// EFFECT: replace the current token and span with the given one
962 pub fn replace_token(&mut self,
966 self.last_span
= mk_sp(self.span
.lo
, lo
);
968 self.span
= mk_sp(lo
, hi
);
970 pub fn buffer_length(&mut self) -> isize {
971 if self.buffer_start
<= self.buffer_end
{
972 return self.buffer_end
- self.buffer_start
;
974 return (4 - self.buffer_start
) + self.buffer_end
;
976 pub fn look_ahead
<R
, F
>(&mut self, distance
: usize, f
: F
) -> R
where
977 F
: FnOnce(&token
::Token
) -> R
,
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;
984 f(&self.buffer
[((self.buffer_start
+ dist
- 1) & 3) as usize].tok
)
986 pub fn fatal(&self, m
: &str) -> diagnostic
::FatalError
{
987 self.sess
.span_diagnostic
.span_fatal(self.span
, m
)
989 pub fn span_fatal(&self, sp
: Span
, m
: &str) -> diagnostic
::FatalError
{
990 self.sess
.span_diagnostic
.span_fatal(sp
, m
)
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
997 pub fn span_note(&self, sp
: Span
, m
: &str) {
998 self.sess
.span_diagnostic
.span_note(sp
, m
)
1000 pub fn span_help(&self, sp
: Span
, m
: &str) {
1001 self.sess
.span_diagnostic
.span_help(sp
, m
)
1003 pub fn span_suggestion(&self, sp
: Span
, m
: &str, n
: String
) {
1004 self.sess
.span_diagnostic
.span_suggestion(sp
, m
, n
)
1006 pub fn fileline_help(&self, sp
: Span
, m
: &str) {
1007 self.sess
.span_diagnostic
.fileline_help(sp
, m
)
1009 pub fn bug(&self, m
: &str) -> ! {
1010 self.sess
.span_diagnostic
.span_bug(self.span
, m
)
1012 pub fn warn(&self, m
: &str) {
1013 self.sess
.span_diagnostic
.span_warn(self.span
, m
)
1015 pub fn span_warn(&self, sp
: Span
, m
: &str) {
1016 self.sess
.span_diagnostic
.span_warn(sp
, m
)
1018 pub fn span_err(&self, sp
: Span
, m
: &str) {
1019 self.sess
.span_diagnostic
.span_err(sp
, m
)
1021 pub fn span_bug(&self, sp
: Span
, m
: &str) -> ! {
1022 self.sess
.span_diagnostic
.span_bug(sp
, m
)
1024 pub fn abort_if_errors(&self) {
1025 self.sess
.span_diagnostic
.handler().abort_if_errors();
1028 pub fn id_to_interned_str(&mut self, id
: Ident
) -> InternedString
{
1032 /// Is the current token one of the keywords that signals a bare function
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
)
1040 pub fn get_lifetime(&mut self) -> ast
::Ident
{
1042 token
::Lifetime(ref ident
) => *ident
,
1043 _
=> self.bug("not a lifetime"),
1047 pub fn parse_for_in_type(&mut self) -> PResult
<Ty_
> {
1049 Parses whatever can come after a `for` keyword in a type.
1050 The `for` has already been consumed.
1054 - for <'lt> |S| -> T
1058 - for <'lt> [unsafe] [extern "ABI"] fn (S) -> T
1059 - for <'lt> path::foo(a, b)
1064 let lo
= self.span
.lo
;
1066 let lifetime_defs
= try
!(self.parse_late_bound_lifetime_defs());
1068 // examine next token to decide to do
1069 if self.token_is_bare_fn_keyword() {
1070 self.parse_ty_bare_fn(lifetime_defs
)
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
))
1083 Some(TraitTyParamBound(poly_trait_ref
, TraitBoundModifier
::None
)).into_iter()
1084 .chain(other_bounds
.into_vec())
1086 Ok(ast
::TyPolyTraitRef(all_bounds
))
1090 pub fn parse_ty_path(&mut self) -> PResult
<Ty_
> {
1091 Ok(TyPath(None
, try
!(self.parse_path(LifetimeAndTypesWithoutColons
))))
1094 /// parse a TyBareFn type:
1095 pub fn parse_ty_bare_fn(&mut self, lifetime_defs
: Vec
<ast
::LifetimeDef
>) -> PResult
<Ty_
> {
1098 [unsafe] [extern "ABI"] fn <'lt> (S) -> T
1099 ^~~~^ ^~~~^ ^~~~^ ^~^ ^
1102 | | | Argument types
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
)
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
{
1123 Ok(TyBareFn(P(BareFnTy
{
1126 lifetimes
: lifetime_defs
,
1131 /// Parses an obsolete closure kind (`&:`, `&mut:`, or `:`).
1132 pub fn parse_obsolete_closure_kind(&mut self) -> PResult
<()> {
1133 let lo
= self.span
.lo
;
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
)
1143 self.token
== token
::BinOp(token
::And
) &&
1144 self.look_ahead(1, |t
| *t
== token
::Colon
)
1149 try
!(self.eat(&token
::Colon
))
1156 let span
= mk_sp(lo
, self.span
.hi
);
1157 self.obsolete(span
, ObsoleteSyntax
::ClosureKind
);
1161 pub fn parse_unsafety(&mut self) -> PResult
<Unsafety
> {
1162 if try
!(self.eat_keyword(keywords
::Unsafe
)) {
1163 return Ok(Unsafety
::Unsafe
);
1165 return Ok(Unsafety
::Normal
);
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
),
1175 |p
| -> PResult
<P
<TraitItem
>> {
1176 maybe_whole
!(no_clone p
, NtTraitItem
);
1177 let mut attrs
= p
.parse_outer_attributes();
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
) {
1191 let expr
= try
!(p
.parse_expr_nopanic());
1192 try
!(p
.commit_expr_expecting(&expr
, token
::Semi
));
1195 try
!(p
.expect(&token
::Semi
));
1198 (ident
, ConstTraitItem(ty
, default))
1200 let (constness
, unsafety
, abi
) = try
!(p
.parse_fn_front_matter());
1202 let ident
= try
!(p
.parse_ident());
1203 let mut generics
= try
!(p
.parse_generics());
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
1209 p
.parse_arg_general(false)
1212 generics
.where_clause
= try
!(p
.parse_where_clause());
1213 let sig
= ast
::MethodSig
{
1215 constness
: constness
,
1219 explicit_self
: explicit_self
,
1222 let body
= match p
.token
{
1225 debug
!("parse_trait_methods(): parsing required method");
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());
1237 let token_str
= p
.this_token_to_string();
1238 return Err(p
.fatal(&format
!("expected `;` or `{{`, found `{}`",
1242 (ident
, ast
::MethodTraitItem(sig
, body
))
1246 id
: ast
::DUMMY_NODE_ID
,
1250 span
: mk_sp(lo
, p
.last_span
.hi
),
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 }
)
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.span
))
1268 Ok(Return(try
!(self.parse_ty_nopanic())))
1271 let pos
= self.span
.lo
;
1272 Ok(DefaultReturn(mk_sp(pos
, pos
)))
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());
1281 if !try
!(self.eat(&token
::BinOp(token
::Plus
)) ){
1285 let bounds
= try
!(self.parse_ty_param_bounds(BoundParsingMode
::Bare
));
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");
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}
))
1302 pub fn parse_ty_nopanic(&mut self) -> PResult
<P
<Ty
>> {
1303 maybe_whole
!(no_clone
self, NtTy
);
1305 let lo
= self.span
.lo
;
1307 let t
= if self.check(&token
::OpenDelim(token
::Paren
)) {
1310 // (t) is a parenthesized ty
1311 // (t,) is the type of a tuple with only one field,
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
) {
1326 try
!(self.expect(&token
::CloseDelim(token
::Paren
)));
1327 if ts
.len() == 1 && !last_comma
{
1328 TyParen(ts
.into_iter().nth(0).unwrap())
1332 } else if self.check(&token
::BinOp(token
::Star
)) {
1333 // STAR POINTER (bare pointer?)
1335 TyPtr(try
!(self.parse_ptr()))
1336 } else if self.check(&token
::OpenDelim(token
::Bracket
)) {
1338 try
!(self.expect(&token
::OpenDelim(token
::Bracket
)));
1339 let t
= try
!(self.parse_ty_sum());
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()) {
1345 Some(suffix
) => TyFixedLengthVec(t
, suffix
)
1347 try
!(self.expect(&token
::CloseDelim(token
::Bracket
)));
1349 } else if self.check(&token
::BinOp(token
::And
)) ||
1350 self.token
== token
::AndAnd
{
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() {
1358 try
!(self.parse_ty_bare_fn(Vec
::new()))
1359 } else if try
!(self.eat_keyword_noexpect(keywords
::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
)));
1366 } else if try
!(self.eat_lt()) {
1369 try
!(self.parse_qualified_path(NoTypesAllowed
));
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
) {
1379 let delim
= try
!(self.expect_open_delim());
1380 let tts
= try
!(self.parse_seq_to_end(&token
::CloseDelim(delim
),
1382 |p
| p
.parse_token_tree()));
1383 let hi
= self.span
.hi
;
1384 TyMac(spanned(lo
, hi
, MacInvocTT(path
, tts
, EMPTY_CTXT
)))
1389 } else if try
!(self.eat(&token
::Underscore
) ){
1390 // TYPE TO BE INFERRED
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
[..]));
1398 let sp
= mk_sp(lo
, self.last_span
.hi
);
1399 Ok(P(Ty {id: ast::DUMMY_NODE_ID, node: t, span: sp}
))
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());
1406 let mt
= try
!(self.parse_mt());
1407 return Ok(TyRptr(opt_lifetime
, mt
));
1410 pub fn parse_ptr(&mut self) -> PResult
<MutTy
> {
1411 let mutbl
= if try
!(self.eat_keyword(keywords
::Mut
) ){
1413 } else if try
!(self.eat_keyword(keywords
::Const
) ){
1416 let span
= self.last_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`");
1423 let t
= try
!(self.parse_ty_nopanic());
1424 Ok(MutTy { ty: t, mutbl: mutbl }
)
1427 pub fn is_named_argument(&mut self) -> bool
{
1428 let offset
= match self.token
{
1429 token
::BinOp(token
::And
) => 1,
1431 _
if self.token
.is_keyword(keywords
::Mut
) => 1,
1435 debug
!("parser is_named_argument offset:{}", offset
);
1438 is_plain_ident_or_underscore(&self.token
)
1439 && self.look_ahead(1, |t
| *t
== token
::Colon
)
1441 self.look_ahead(offset
, |t
| is_plain_ident_or_underscore(t
))
1442 && self.look_ahead(offset
+ 1, |t
| *t
== token
::Colon
)
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:{})",
1452 let pat
= try
!(self.parse_pat_nopanic());
1454 try
!(self.expect(&token
::Colon
));
1457 debug
!("parse_arg_general ident_to_pat");
1458 ast_util
::ident_to_pat(ast
::DUMMY_NODE_ID
,
1460 special_idents
::invalid
)
1463 let t
= try
!(self.parse_ty_sum());
1468 id
: ast
::DUMMY_NODE_ID
,
1472 /// Parse a single function argument
1473 pub fn parse_arg(&mut self) -> PResult
<Arg
> {
1474 self.parse_arg_general(true)
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())
1484 id
: ast
::DUMMY_NODE_ID
,
1486 span
: mk_sp(self.span
.lo
, self.span
.hi
),
1492 id
: ast
::DUMMY_NODE_ID
1496 pub fn maybe_parse_fixed_length_of_vec(&mut self) -> PResult
<Option
<P
<ast
::Expr
>>> {
1497 if self.check(&token
::Semi
) {
1499 Ok(Some(try
!(self.parse_expr_nopanic())))
1505 /// Matches token_lit = LIT_INTEGER | ...
1506 pub fn lit_from_token(&self, tok
: &token
::Token
) -> PResult
<Lit_
> {
1508 token
::Interpolated(token
::NtExpr(ref v
)) => {
1510 ExprLit(ref lit
) => { Ok(lit.node.clone()) }
1511 _
=> { return Err(self.unexpected_last(tok)); }
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)),
1519 // there are some valid suffixes for integer and
1520 // float literals, so all the handling is done
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
,
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
,
1537 LitStr(token
::intern_and_get_ident(&parse
::str_lit(&s
.as_str())),
1540 token
::StrRaw(s
, n
) => {
1543 token
::intern_and_get_ident(&parse
::raw_str_lit(&s
.as_str())),
1546 token
::ByteStr(i
) =>
1547 (true, LitByteStr(parse
::byte_str_lit(&i
.as_str()))),
1548 token
::ByteStrRaw(i
, _
) =>
1550 LitByteStr(Rc
::new(i
.to_string().into_bytes()))),
1554 let sp
= self.last_span
;
1555 self.expect_no_suffix(sp
, &*format
!("{} literal", lit
.short_name()), suf
)
1560 _
=> { return Err(self.unexpected_last(tok)); }
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
) ){
1569 } else if try
!(self.eat_keyword(keywords
::False
) ){
1572 let token
= try
!(self.bump_and_get());
1573 let lit
= try
!(self.lit_from_token(&token
));
1576 Ok(codemap
::Spanned { node: lit, span: mk_sp(lo, self.last_span.hi) }
)
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
)));
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
));
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
))
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
))
1616 position
: path
.segments
.len()
1619 try
!(self.expect(&token
::Gt
));
1620 try
!(self.expect(&token
::ModSep
));
1622 let segments
= match mode
{
1623 LifetimeAndTypesWithoutColons
=> {
1624 try
!(self.parse_path_segments_without_colons())
1626 LifetimeAndTypesWithColons
=> {
1627 try
!(self.parse_path_segments_with_colons())
1630 try
!(self.parse_path_segments_without_types())
1633 path
.segments
.extend(segments
);
1635 path
.span
.hi
= self.last_span
.hi
;
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
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())),
1650 if let Some(token
::Interpolated(token
::NtPath(path
))) = found
{
1654 let lo
= self.span
.lo
;
1655 let is_global
= try
!(self.eat(&token
::ModSep
));
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())
1664 LifetimeAndTypesWithColons
=> {
1665 try
!(self.parse_path_segments_with_colons())
1668 try
!(self.parse_path_segments_without_types())
1672 // Assemble the span.
1673 let span
= mk_sp(lo
, self.last_span
.hi
);
1675 // Assemble the result.
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();
1690 // First, parse an identifier.
1691 let identifier
= try
!(self.parse_ident_or_self_type());
1693 // Parse types, optionally.
1694 let parameters
= if try
!(self.eat_lt() ){
1695 let (lifetimes
, types
, bindings
) = try
!(self.parse_generic_values_after_lt());
1697 ast
::AngleBracketedParameters(ast
::AngleBracketedParameterData
{
1698 lifetimes
: lifetimes
,
1699 types
: OwnedSlice
::from_vec(types
),
1700 bindings
: OwnedSlice
::from_vec(bindings
),
1702 } else if try
!(self.eat(&token
::OpenDelim(token
::Paren
)) ){
1703 let lo
= self.last_span
.lo
;
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()));
1710 let output_ty
= if try
!(self.eat(&token
::RArrow
) ){
1711 Some(try
!(self.parse_ty_nopanic()))
1716 let hi
= self.last_span
.hi
;
1718 ast
::ParenthesizedParameters(ast
::ParenthesizedParameterData
{
1719 span
: mk_sp(lo
, hi
),
1724 ast
::PathParameters
::none()
1727 // Assemble and push the result.
1728 segments
.push(ast
::PathSegment
{ identifier
: identifier
,
1729 parameters
: parameters
});
1731 // Continue only if we see a `::`
1732 if !try
!(self.eat(&token
::ModSep
) ){
1733 return Ok(segments
);
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();
1743 // First, parse an identifier.
1744 let identifier
= try
!(self.parse_ident_or_self_type());
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()
1752 return Ok(segments
);
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
),
1768 // Consumed `a::b::<T,U>`, check for `::` before proceeding
1769 if !try
!(self.eat(&token
::ModSep
) ){
1770 return Ok(segments
);
1773 // Consumed `a::`, go look for `b`
1774 segments
.push(ast
::PathSegment
{
1775 identifier
: identifier
,
1776 parameters
: ast
::PathParameters
::none(),
1785 pub fn parse_path_segments_without_types(&mut self) -> PResult
<Vec
<ast
::PathSegment
>> {
1786 let mut segments
= Vec
::new();
1788 // First, parse an identifier.
1789 let identifier
= try
!(self.parse_ident_or_self_type());
1791 // Assemble and push the result.
1792 segments
.push(ast
::PathSegment
{
1793 identifier
: identifier
,
1794 parameters
: ast
::PathParameters
::none()
1797 // If we do not see a `::`, stop.
1798 if !try
!(self.eat(&token
::ModSep
) ){
1799 return Ok(segments
);
1804 /// parses 0 or 1 lifetime
1805 pub fn parse_opt_lifetime(&mut self) -> PResult
<Option
<ast
::Lifetime
>> {
1807 token
::Lifetime(..) => {
1808 Ok(Some(try
!(self.parse_lifetime())))
1816 /// Parses a single lifetime
1817 /// Matches lifetime = LIFETIME
1818 pub fn parse_lifetime(&mut self) -> PResult
<ast
::Lifetime
> {
1820 token
::Lifetime(i
) => {
1821 let span
= self.span
;
1823 return Ok(ast
::Lifetime
{
1824 id
: ast
::DUMMY_NODE_ID
,
1830 return Err(self.fatal(&format
!("expected a lifetime name")));
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
>> {
1839 let mut res
= Vec
::new();
1842 token
::Lifetime(_
) => {
1843 let lifetime
= try
!(self.parse_lifetime());
1845 if try
!(self.eat(&token
::Colon
) ){
1846 try
!(self.parse_lifetimes(token
::BinOp(token
::Plus
)))
1850 res
.push(ast
::LifetimeDef
{ lifetime
: lifetime
,
1860 token
::Comma
=> { try!(self.bump());}
1861 token
::Gt
=> { return Ok(res); }
1862 token
::BinOp(token
::Shr
) => { return Ok(res); }
1864 let this_token_str
= self.this_token_to_string();
1865 let msg
= format
!("expected `,` or `>` after lifetime \
1868 return Err(self.fatal(&msg
[..]));
1874 /// matches lifetimes = ( lifetime ) | ( lifetime , lifetimes ) actually, it matches the empty
1875 /// one too, but putting that in there messes up the grammar....
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
>> {
1882 let mut res
= Vec
::new();
1885 token
::Lifetime(_
) => {
1886 res
.push(try
!(self.parse_lifetime()));
1893 if self.token
!= sep
{
1901 /// Parse mutability declaration (mut/const/imm)
1902 pub fn parse_mutability(&mut self) -> PResult
<Mutability
> {
1903 if try
!(self.eat_keyword(keywords
::Mut
) ){
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());
1918 ident
: spanned(lo
, hi
, i
),
1919 span
: mk_sp(lo
, e
.span
.hi
),
1924 pub fn mk_expr(&mut self, lo
: BytePos
, hi
: BytePos
, node
: Expr_
) -> P
<Expr
> {
1926 id
: ast
::DUMMY_NODE_ID
,
1928 span
: mk_sp(lo
, hi
),
1932 pub fn mk_unary(&mut self, unop
: ast
::UnOp
, expr
: P
<Expr
>) -> ast
::Expr_
{
1933 ExprUnary(unop
, expr
)
1936 pub fn mk_binary(&mut self, binop
: ast
::BinOp
, lhs
: P
<Expr
>, rhs
: P
<Expr
>) -> ast
::Expr_
{
1937 ExprBinary(binop
, lhs
, rhs
)
1940 pub fn mk_call(&mut self, f
: P
<Expr
>, args
: Vec
<P
<Expr
>>) -> ast
::Expr_
{
1944 fn mk_method_call(&mut self,
1945 ident
: ast
::SpannedIdent
,
1949 ExprMethodCall(ident
, tps
, args
)
1952 pub fn mk_index(&mut self, expr
: P
<Expr
>, idx
: P
<Expr
>) -> ast
::Expr_
{
1953 ExprIndex(expr
, idx
)
1956 pub fn mk_range(&mut self,
1957 start
: Option
<P
<Expr
>>,
1958 end
: Option
<P
<Expr
>>)
1960 ExprRange(start
, end
)
1963 pub fn mk_field(&mut self, expr
: P
<Expr
>, ident
: ast
::SpannedIdent
) -> ast
::Expr_
{
1964 ExprField(expr
, ident
)
1967 pub fn mk_tup_field(&mut self, expr
: P
<Expr
>, idx
: codemap
::Spanned
<usize>) -> ast
::Expr_
{
1968 ExprTupField(expr
, idx
)
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
)
1976 pub fn mk_mac_expr(&mut self, lo
: BytePos
, hi
: BytePos
, m
: Mac_
) -> 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
),
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
)),
1992 id
: ast
::DUMMY_NODE_ID
,
1993 node
: ExprLit(lv_lit
),
1998 fn expect_open_delim(&mut self) -> PResult
<token
::DelimToken
> {
1999 self.expected_tokens
.push(TokenType
::Token(token
::Gt
));
2001 token
::OpenDelim(delim
) => {
2005 _
=> Err(self.fatal("expected open delimiter")),
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);
2015 let lo
= self.span
.lo
;
2016 let mut hi
= self.span
.hi
;
2020 // Note: when adding new syntax here, don't forget to adjust Token::can_begin_expr().
2022 token
::OpenDelim(token
::Paren
) => {
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;
2038 trailing_comma
= false;
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())))
2048 Ok(self.mk_expr(lo
, hi
, ExprTup(es
)))
2051 token
::OpenDelim(token
::Brace
) => {
2052 return self.parse_block_expr(lo
, DefaultBlock
);
2054 token
::BinOp(token
::Or
) | token
::OrOr
=> {
2055 let lo
= self.span
.lo
;
2056 return self.parse_lambda_expr(lo
, CaptureByRef
);
2058 token
::Ident(id @ ast
::Ident
{
2059 name
: token
::SELF_KEYWORD_NAME
,
2061 }, token
::Plain
) => {
2063 let path
= ast_util
::ident_to_path(mk_sp(lo
, hi
), id
);
2064 ex
= ExprPath(None
, path
);
2065 hi
= self.last_span
.hi
;
2067 token
::OpenDelim(token
::Bracket
) => {
2070 if self.check(&token
::CloseDelim(token
::Bracket
)) {
2073 ex
= ExprVec(Vec
::new());
2076 let first_expr
= try
!(self.parse_expr_nopanic());
2077 if self.check(&token
::Semi
) {
2078 // Repeating array syntax: [ 0; 512 ]
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.
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()))
2091 let mut exprs
= vec
!(first_expr
);
2092 exprs
.extend(remaining_exprs
);
2093 ex
= ExprVec(exprs
);
2095 // Vector with one element.
2096 try
!(self.expect(&token
::CloseDelim(token
::Bracket
)));
2097 ex
= ExprVec(vec
!(first_expr
));
2100 hi
= self.last_span
.hi
;
2103 if try
!(self.eat_lt()){
2105 try
!(self.parse_qualified_path(LifetimeAndTypesWithColons
));
2107 return Ok(self.mk_expr(lo
, hi
, ExprPath(Some(qself
), path
)));
2109 if try
!(self.eat_keyword(keywords
::Move
) ){
2110 let lo
= self.last_span
.lo
;
2111 return self.parse_lambda_expr(lo
, CaptureByValue
);
2113 if try
!(self.eat_keyword(keywords
::If
)) {
2114 return self.parse_if_expr();
2116 if try
!(self.eat_keyword(keywords
::For
) ){
2117 let lo
= self.last_span
.lo
;
2118 return self.parse_for_expr(None
, lo
);
2120 if try
!(self.eat_keyword(keywords
::While
) ){
2121 let lo
= self.last_span
.lo
;
2122 return self.parse_while_expr(None
, lo
);
2124 if self.token
.is_lifetime() {
2125 let lifetime
= self.get_lifetime();
2126 let lo
= self.span
.lo
;
2128 try
!(self.expect(&token
::Colon
));
2129 if try
!(self.eat_keyword(keywords
::While
) ){
2130 return self.parse_while_expr(Some(lifetime
), lo
)
2132 if try
!(self.eat_keyword(keywords
::For
) ){
2133 return self.parse_for_expr(Some(lifetime
), lo
)
2135 if try
!(self.eat_keyword(keywords
::Loop
) ){
2136 return self.parse_loop_expr(Some(lifetime
), lo
)
2138 return Err(self.fatal("expected `while`, `for`, or `loop` after a label"))
2140 if try
!(self.eat_keyword(keywords
::Loop
) ){
2141 let lo
= self.last_span
.lo
;
2142 return self.parse_loop_expr(None
, lo
);
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(),
2155 let hi
= self.last_span
.hi
;
2156 return Ok(self.mk_expr(lo
, hi
, ex
));
2158 if try
!(self.eat_keyword(keywords
::Match
) ){
2159 return self.parse_match_expr();
2161 if try
!(self.eat_keyword(keywords
::Unsafe
) ){
2162 return self.parse_block_expr(
2164 UnsafeBlock(ast
::UserProvided
));
2166 if try
!(self.eat_keyword(keywords
::Return
) ){
2167 if self.token
.can_begin_expr() {
2168 let e
= try
!(self.parse_expr_nopanic());
2170 ex
= ExprRet(Some(e
));
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(),
2182 ex
= ExprBreak(None
);
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
) {
2190 try
!(self.parse_path(LifetimeAndTypesWithColons
));
2192 // `!`, as an operator, is prefix, so we know this isn't that
2193 if self.check(&token
::Not
) {
2194 // MACRO INVOCATION expression
2197 let delim
= try
!(self.expect_open_delim());
2198 let tts
= try
!(self.parse_seq_to_end(
2199 &token
::CloseDelim(delim
),
2201 |p
| p
.parse_token_tree()));
2202 let hi
= self.last_span
.hi
;
2204 return Ok(self.mk_mac_expr(lo
,
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
2217 // It's a struct literal.
2219 let mut fields
= Vec
::new();
2220 let mut base
= None
;
2222 while self.token
!= token
::CloseDelim(token
::Brace
) {
2223 if try
!(self.eat(&token
::DotDot
) ){
2224 base
= Some(try
!(self.parse_expr_nopanic()));
2228 fields
.push(try
!(self.parse_field()));
2229 try
!(self.commit_expr(&*fields
.last().unwrap().expr
,
2231 &[token
::CloseDelim(token
::Brace
)]));
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");
2243 try
!(self.expect(&token
::CloseDelim(token
::Brace
)));
2244 ex
= ExprStruct(pth
, fields
, base
);
2245 return Ok(self.mk_expr(lo
, hi
, ex
));
2250 ex
= ExprPath(None
, pth
);
2252 // other literal expression
2253 let lit
= try
!(self.parse_lit());
2255 ex
= ExprLit(P(lit
));
2260 return Ok(self.mk_expr(lo
, hi
, ex
));
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
)));
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
)
2277 pub fn parse_dot_or_call_expr_with(&mut self, e0
: P
<Expr
>) -> PResult
<P
<Expr
>> {
2283 if try
!(self.eat(&token
::Dot
) ){
2285 token
::Ident(i
, _
) => {
2286 let dot
= self.last_span
.hi
;
2289 let (_
, tys
, bindings
) = if try
!(self.eat(&token
::ModSep
) ){
2290 try
!(self.expect_lt());
2291 try
!(self.parse_generic_values_after_lt())
2293 (Vec
::new(), Vec
::new(), Vec
::new())
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");
2301 // expr.f() method call
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()))
2310 hi
= self.last_span
.hi
;
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
);
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");
2325 let id
= spanned(dot
, hi
, i
);
2326 let field
= self.mk_field(e
, id
);
2327 e
= self.mk_expr(lo
, hi
, field
);
2331 token
::Literal(token
::Integer(n
), suf
) => {
2334 // A tuple index may not have a suffix
2335 self.expect_no_suffix(sp
, "tuple index", suf
);
2337 let dot
= self.last_span
.hi
;
2341 let index
= n
.as_str().parse
::<usize>().ok();
2344 let id
= spanned(dot
, hi
, n
);
2345 let field
= self.mk_tup_field(e
, id
);
2346 e
= self.mk_expr(lo
, hi
, field
);
2349 let last_span
= self.last_span
;
2350 self.span_err(last_span
, "invalid tuple or tuple struct index");
2354 token
::Literal(token
::Float(n
), _suf
) => {
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() {
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())));
2370 self.abort_if_errors();
2373 _
=> return Err(self.unexpected())
2377 if self.expr_is_complete(&*e
) { break; }
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()))
2387 hi
= self.last_span
.hi
;
2389 let nd
= self.mk_call(e
, es
);
2390 e
= self.mk_expr(lo
, hi
, nd
);
2394 // Could be either an index expression or a slicing expression.
2395 token
::OpenDelim(token
::Bracket
) => {
2397 let ix
= try
!(self.parse_expr_nopanic());
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
)
2409 // Parse unquoted tokens after a `$` in a token tree
2410 fn parse_unquoted(&mut self) -> PResult
<TokenTree
> {
2411 let mut sp
= self.span
;
2412 let (name
, namep
) = match self.token
{
2416 if self.token
== token
::OpenDelim(token
::Paren
) {
2417 let Spanned { node: seq, span: seq_span }
= try
!(self.parse_seq(
2418 &token
::OpenDelim(token
::Paren
),
2419 &token
::CloseDelim(token
::Paren
),
2421 |p
| p
.parse_token_tree()
2423 let (sep
, repeat
) = try
!(self.parse_sep_and_kleene_op());
2424 let name_num
= macro_parser
::count_names(&seq
);
2425 return Ok(TtSequence(mk_sp(sp
.lo
, seq_span
.hi
),
2426 Rc
::new(SequenceRepetition
{
2430 num_captures
: name_num
2432 } else if self.token
.is_keyword_allow_following_colon(keywords
::Crate
) {
2434 return Ok(TtToken(sp
, SpecialVarNt(SpecialMacroVar
::CrateMacroVar
)));
2436 sp
= mk_sp(sp
.lo
, self.span
.hi
);
2437 let namep
= match self.token { token::Ident(_, p) => p, _ => token::Plain }
;
2438 let name
= try
!(self.parse_ident());
2442 token
::SubstNt(name
, namep
) => {
2448 // continue by trying to parse the `:ident` after `$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()) {
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
)))
2458 Ok(TtToken(sp
, SubstNt(name
, namep
)))
2462 pub fn check_unknown_macro_variable(&mut self) -> PResult
<()> {
2463 if self.quote_depth
== 0 {
2465 token
::SubstNt(name
, _
) =>
2466 return Err(self.fatal(&format
!("unknown macro variable `{}`",
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
))
2483 token
::BinOp(token
::Plus
) => {
2484 try
!(parser
.bump());
2485 Ok(Some(ast
::OneOrMore
))
2491 match try
!(parse_kleene_op(self)) {
2492 Some(kleene_op
) => return Ok((None
, kleene_op
)),
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 `+`"))
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
2510 maybe_whole
!(deref
self, NtTT
);
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
);
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() {
2526 Some(&sp
) => p
.span_note(sp
, "unclosed delimiter"),
2528 let token_str
= p
.this_token_to_string();
2529 Err(p
.fatal(&format
!("incorrect close delimiter: `{}`",
2532 /* we ought to allow different depths of unquotation */
2533 token
::Dollar
| token
::SubstNt(..) if p
.quote_depth
> 0 => {
2537 Ok(TtToken(p
.span
, try
!(p
.bump_and_get())))
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?");
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 "));
2552 token
::OpenDelim(delim
) => {
2553 // The span for beginning of the delimited section
2554 let pre_span
= self.span
;
2556 // Parse the open delimiter.
2557 self.open_braces
.push(self.span
);
2558 let open_span
= self.span
;
2561 // Parse the token trees within the delimiters
2562 let tts
= try
!(self.parse_seq_to_before_end(
2563 &token
::CloseDelim(delim
),
2565 |p
| p
.parse_token_tree()
2568 // Parse the close delimiter.
2569 let close_span
= self.span
;
2571 self.open_braces
.pop().unwrap();
2573 // Expand to cover the entire delimited token tree
2574 let span
= Span { hi: close_span.hi, ..pre_span }
;
2576 Ok(TtDelimited(span
, Rc
::new(Delimited
{
2578 open_span
: open_span
,
2580 close_span
: close_span
,
2583 _
=> parse_non_delim_tt_tok(self),
2587 // parse a stream of tokens into a list of TokenTree's,
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()));
2597 /// Parse a prefix-operator expr
2598 pub fn parse_prefix_expr(&mut self) -> PResult
<P
<Expr
>> {
2599 let lo
= self.span
.lo
;
2602 // Note: when adding new unary operators, don't forget to adjust Token::can_begin_expr()
2607 let e
= try
!(self.parse_prefix_expr());
2609 ex
= self.mk_unary(UnNot
, e
);
2611 token
::BinOp(token
::Minus
) => {
2613 let e
= try
!(self.parse_prefix_expr());
2615 ex
= self.mk_unary(UnNeg
, e
);
2617 token
::BinOp(token
::Star
) => {
2619 let e
= try
!(self.parse_prefix_expr());
2621 ex
= self.mk_unary(UnDeref
, e
);
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());
2628 ex
= ExprAddrOf(m
, e
);
2630 token
::Ident(_
, _
) => {
2631 if !self.check_keyword(keywords
::Box
) && !self.check_keyword(keywords
::In
) {
2632 return self.parse_dot_or_call_expr();
2635 let lo
= self.span
.lo
;
2636 let keyword_hi
= self.span
.hi
;
2638 let is_in
= self.token
.is_keyword(keywords
::In
);
2642 let place
= try
!(self.parse_expr_res(Restrictions
::RESTRICTION_NO_STRUCT_LITERAL
));
2643 let blk
= try
!(self.parse_block());
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
));
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 }`, ...
2654 // ... but for now: check for a place: `box(PLACE) EXPR`.
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> }`)");
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();
2672 &format
!("expected expression, found `{}`",
2673 this_token_to_string
));
2675 // Spanning just keyword avoids constructing
2676 // printout of arg expression (which starts
2677 // with parenthesis, as established above).
2679 let box_span
= mk_sp(lo
, keyword_hi
);
2680 self.span_suggestion(box_span
,
2681 "try using `box ()` instead:",
2683 self.abort_if_errors();
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
));
2692 // Otherwise, we use the unique pointer default.
2693 let subexpression
= try
!(self.parse_prefix_expr());
2694 hi
= subexpression
.span
.hi
;
2696 // FIXME (pnkfelix): After working out kinks with box
2697 // desugaring, should be `ExprBox(None, subexpression)`
2699 ex
= self.mk_unary(UnUniq
, subexpression
);
2701 _
=> return self.parse_dot_or_call_expr()
2703 return Ok(self.mk_expr(lo
, hi
, ex
));
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)
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); }
2716 self.expected_tokens
.push(TokenType
::Operator
);
2718 let cur_op_span
= self.span
;
2719 let cur_opt
= self.token
.to_binop();
2722 if ast_util
::is_comparison_binop(cur_op
) {
2723 self.check_no_chained_comparison(&*lhs
, cur_op
)
2725 let cur_prec
= operator_prec(cur_op
);
2726 if cur_prec
>= min_prec
{
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
)
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
,
2744 ExprCast(lhs
, rhs
));
2745 self.parse_more_binops(_as
, min_prec
)
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
));
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");
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
>> {
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
;
2786 let opt_end
= if self.is_at_start_of_range_notation_rhs() {
2787 let end
= try
!(self.parse_binops());
2793 let ex
= self.mk_range(None
, opt_end
);
2794 Ok(self.mk_expr(lo
, hi
, ex
))
2797 let lhs
= try
!(self.parse_binops());
2798 self.parse_assign_expr_with(lhs
)
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
;
2809 let rhs
= try
!(self.parse_expr_res(restrictions
));
2810 Ok(self.mk_expr(lhs
.span
.lo
, rhs
.span
.hi
, ExprAssign(lhs
, rhs
)))
2812 token
::BinOpEq(op
) => {
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
,
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
))
2832 // A range expression, either `expr..expr` or `expr..`.
2834 let lo
= lhs
.span
.lo
;
2835 let mut hi
= self.span
.hi
;
2838 let opt_end
= if self.is_at_start_of_range_notation_rhs() {
2839 let end
= try
!(self.parse_binops());
2845 let range
= self.mk_range(Some(lhs
), opt_end
);
2846 return Ok(self.mk_expr(lo
, hi
, range
));
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
);
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();
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
;
2882 Ok(self.mk_expr(lo
, hi
, ExprIf(cond
, thn
, els
)))
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
))
2899 Ok(self.mk_expr(lo
, hi
, ExprIfLet(pat
, expr
, thn
, els
)))
2903 pub fn parse_lambda_expr(&mut self, lo
: BytePos
, capture_clause
: CaptureClause
)
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());
2913 id
: ast
::DUMMY_NODE_ID
,
2915 span
: body_expr
.span
,
2916 expr
: Some(body_expr
),
2917 rules
: DefaultBlock
,
2921 // If an explicit return type is given, require a
2922 // block to appear (RFC 968).
2923 try
!(self.parse_block())
2930 ExprClosure(capture_clause
, decl
, body
)))
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();
2937 let blk
= try
!(self.parse_block());
2938 return Ok(self.mk_expr(blk
.span
.lo
, blk
.span
.hi
, ExprBlock(blk
)));
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>`
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
;
2953 Ok(self.mk_expr(span_lo
, hi
, ExprForLoop(pat
, expr
, loop_block
, opt_ident
)))
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
);
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
)));
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
)));
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
)))
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()));
2995 let hi
= self.span
.hi
;
2997 return Ok(self.mk_expr(lo
, hi
, ExprMatch(discriminant
, arms
, MatchSource
::Normal
)));
3000 pub fn parse_arm_nopanic(&mut self) -> PResult
<Arm
> {
3001 maybe_whole
!(no_clone
self, NtArm
);
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()));
3009 try
!(self.expect(&token
::FatArrow
));
3010 let expr
= try
!(self.parse_expr_res(Restrictions
::RESTRICTION_STMT_EXPR
));
3013 !classify
::expr_is_simple_block(&*expr
)
3014 && self.token
!= token
::CloseDelim(token
::Brace
);
3017 try
!(self.commit_expr(&*expr
, &[token
::Comma
], &[token
::CloseDelim(token
::Brace
)]));
3019 try
!(self.eat(&token
::Comma
));
3030 /// Parse an expression
3031 pub fn parse_expr_nopanic(&mut self) -> PResult
<P
<Expr
>> {
3032 self.parse_expr_res(Restrictions
::empty())
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
;
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
) {
3048 Ok(Some(try
!(self.parse_expr_nopanic())))
3054 /// Parse patterns, separated by '|' s
3055 fn parse_pats(&mut self) -> PResult
<Vec
<P
<Pat
>>> {
3056 let mut pats
= Vec
::new();
3058 pats
.push(try
!(self.parse_pat_nopanic()));
3059 if self.check(&token
::BinOp(token
::Or
)) { try!(self.bump());}
3060 else { return Ok(pats); }
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()));
3074 if fields
.len() == 1 {
3075 try
!(self.expect(&token
::Comma
));
3081 fn parse_pat_vec_elements(
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;
3090 while self.token
!= token
::CloseDelim(token
::Bracket
) {
3094 try
!(self.expect(&token
::Comma
));
3096 if self.token
== token
::CloseDelim(token
::Bracket
)
3097 && (before_slice
|| !after
.is_empty()) {
3103 if self.check(&token
::DotDot
) {
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
),
3113 before_slice
= false;
3119 let subpat
= try
!(self.parse_pat_nopanic());
3120 if before_slice
&& self.check(&token
::DotDot
) {
3122 slice
= Some(subpat
);
3123 before_slice
= false;
3124 } else if before_slice
{
3125 before
.push(subpat
);
3131 Ok((before
, slice
, after
))
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
) {
3143 try
!(self.expect(&token
::Comma
));
3144 // accept trailing commas
3145 if self.check(&token
::CloseDelim(token
::Brace
)) { break }
3148 let lo
= self.span
.lo
;
3151 if self.check(&token
::DotDot
) {
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 `{}`", "}",
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());
3167 let pat
= try
!(self.parse_pat_nopanic());
3169 (pat
, fieldname
, false)
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
;
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
),
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
),
3192 let subpat
= if is_box
{
3194 id
: ast
::DUMMY_NODE_ID
,
3195 node
: PatBox(fieldpat
),
3196 span
: mk_sp(lo
, hi
),
3201 (subpat
, fieldname
, true)
3204 fields
.push(codemap
::Spanned
{ span
: mk_sp(lo
, hi
),
3205 node
: ast
::FieldPat
{ ident
: fieldname
,
3207 is_shorthand
: is_shorthand
}});
3209 return Ok((fields
, etc
));
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
3218 try
!(self.parse_qualified_path(NoTypesAllowed
));
3221 // Parse an unqualified path
3222 (None
, try
!(self.parse_path(LifetimeAndTypesWithColons
)))
3224 let hi
= self.last_span
.hi
;
3225 Ok(self.mk_expr(lo
, hi
, ExprPath(qself
, path
)))
3227 self.parse_literal_maybe_minus()
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
)
3237 /// Parse a pattern.
3238 pub fn parse_pat_nopanic(&mut self) -> PResult
<P
<Pat
>> {
3239 maybe_whole
!(self, NtPat
);
3241 let lo
= self.span
.lo
;
3244 token
::Underscore
=> {
3247 pat
= PatWild(PatWildSingle
);
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
);
3256 token
::OpenDelim(token
::Paren
) => {
3257 // Parse (pat,pat,pat,...) as tuple pattern
3259 let fields
= try
!(self.parse_pat_tuple_elements());
3260 try
!(self.expect(&token
::CloseDelim(token
::Paren
)));
3261 pat
= PatTup(fields
);
3263 token
::OpenDelim(token
::Bracket
) => {
3264 // Parse [pat,pat,...] as slice pattern
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
);
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
)) {
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
);
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}
);
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
)));
3309 let (qself
, path
) = if try
!(self.eat_lt()) {
3310 // Parse a qualified path
3312 try
!(self.parse_qualified_path(NoTypesAllowed
));
3315 // Parse an unqualified path
3316 (None
, try
!(self.parse_path(LifetimeAndTypesWithColons
)))
3319 token
::DotDotDot
=> {
3321 let hi
= self.last_span
.hi
;
3322 let begin
= self.mk_expr(lo
, hi
, ExprPath(qself
, path
));
3324 let end
= try
!(self.parse_pat_range_end());
3325 pat
= PatRange(begin
, end
);
3327 token
::OpenDelim(token
::Brace
) => {
3328 if qself
.is_some() {
3329 let span
= self.span
;
3331 "unexpected `{` after qualified path");
3332 self.abort_if_errors();
3334 // Parse struct pattern
3336 let (fields
, etc
) = try
!(self.parse_pat_fields());
3338 pat
= PatStruct(path
, fields
, etc
);
3340 token
::OpenDelim(token
::Paren
) => {
3341 if qself
.is_some() {
3342 let span
= self.span
;
3344 "unexpected `(` after qualified path");
3345 self.abort_if_errors();
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
3352 try
!(self.expect(&token
::CloseDelim(token
::Paren
)));
3353 pat
= PatEnum(path
, None
);
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
));
3363 _
if qself
.is_some() => {
3364 // Parse qualified path
3365 pat
= PatQPath(qself
.unwrap(), path
);
3368 // Parse nullary enum
3369 pat
= PatEnum(path
, Some(vec
![]));
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
);
3380 pat
= PatLit(begin
);
3386 let hi
= self.last_span
.hi
;
3388 id
: ast
::DUMMY_NODE_ID
,
3390 span
: mk_sp(lo
, hi
),
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
)))
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()))
3415 // just to be friendly, if they write something like
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(
3425 "expected identifier, found enum pattern"))
3428 Ok(PatIdent(binding_mode
, name
, sub
))
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());
3437 if try
!(self.eat(&token
::Colon
) ){
3438 ty
= Some(try
!(self.parse_ty_sum()));
3440 let init
= try
!(self.parse_initializer());
3445 id
: ast
::DUMMY_NODE_ID
,
3446 span
: mk_sp(lo
, self.last_span
.hi
),
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
))))
3457 /// Parse a structure field
3458 fn parse_name_and_ty(&mut self, pr
: Visibility
,
3459 attrs
: Vec
<Attribute
> ) -> PResult
<StructField
> {
3461 Inherited
=> self.span
.lo
,
3462 Public
=> self.last_span
.lo
,
3464 if !self.token
.is_plain_ident() {
3465 return Err(self.fatal("expected ident"));
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
,
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"
3484 _
=> "expected item after attributes",
3487 self.span_err(self.last_span
, message
);
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
))
3495 fn parse_stmt_(&mut self) -> PResult
<Option
<Stmt
>> {
3496 maybe_whole
!(Some deref
self, NtStmt
);
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
);
3505 let attrs
= self.parse_outer_attributes();
3506 let lo
= self.span
.lo
;
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:
3518 check_expected_item(self, &attrs
);
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
));
3525 let id
= match self.token
{
3526 token
::OpenDelim(_
) => token
::special_idents
::invalid
, // no special identifier
3527 _
=> try
!(self.parse_ident()),
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
,
3536 // we only expect an ident if we didn't parse one
3538 let ident_str
= if id
.name
== token
::special_idents
::invalid
.name
{
3543 let tok_str
= self.this_token_to_string();
3544 return Err(self.fatal(&format
!("expected {}`(` or `{{`, found `{}`",
3550 let tts
= try
!(self.parse_unspanned_seq(
3551 &token
::OpenDelim(delim
),
3552 &token
::CloseDelim(delim
),
3554 |p
| p
.parse_token_tree()
3556 let hi
= self.last_span
.hi
;
3558 let style
= if delim
== token
::Brace
{
3561 MacStmtWithoutBraces
3564 if id
.name
== token
::special_idents
::invalid
.name
{
3566 StmtMac(P(spanned(lo
,
3568 MacInvocTT(pth
, tts
, EMPTY_CTXT
))),
3571 // if it has a special ident, it's definitely an item
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");
3583 spanned(lo
, hi
, StmtDecl(
3584 P(spanned(lo
, hi
, DeclItem(
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
))
3592 match try
!(self.parse_item_(attrs
, false)) {
3595 let decl
= P(spanned(lo
, hi
, DeclItem(i
)));
3596 spanned(lo
, hi
, StmtDecl(decl
, ast
::DUMMY_NODE_ID
))
3599 // Do not attempt to parse an expression if we're done here.
3600 if self.token
== token
::Semi
{
3605 if self.token
== token
::CloseDelim(token
::Brace
) {
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
))
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
)
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
);
3627 let lo
= self.span
.lo
;
3629 if !try
!(self.eat(&token
::OpenDelim(token
::Brace
)) ){
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"));
3637 self.parse_block_tail(lo
, DefaultBlock
)
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
);
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
))))
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
;
3656 while !try
!(self.eat(&token
::CloseDelim(token
::Brace
))) {
3657 let Spanned {node, span}
= if let Some(s
) = try
!(self.parse_stmt_()) {
3660 // Found only `;` or `}`.
3665 try
!(self.handle_expression_like_statement(e
, span
, &mut stmts
, &mut expr
));
3667 StmtMac(mac
, MacStmtWithoutBraces
) => {
3668 // statement macro without braces; might be an
3669 // expr depending on whether a semicolon follows
3672 stmts
.push(P(Spanned
{
3673 node
: StmtMac(mac
, MacStmtWithSemicolon
),
3674 span
: mk_sp(span
.lo
, self.span
.hi
),
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(
3692 StmtMac(m
, style
) => {
3693 // statement macro; might be an expr
3696 stmts
.push(P(Spanned
{
3697 node
: StmtMac(m
, MacStmtWithSemicolon
),
3698 span
: mk_sp(span
.lo
, self.span
.hi
),
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
)));
3709 stmts
.push(P(Spanned
{
3710 node
: StmtMac(m
, style
),
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
;
3723 stmts
.push(P(Spanned
{
3725 span
: mk_sp(span
.lo
, hi
)
3734 id
: ast
::DUMMY_NODE_ID
,
3736 span
: mk_sp(lo
, self.last_span
.hi
),
3740 fn handle_expression_like_statement(
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
)]));
3756 let span_with_semi
= Span
{
3758 hi
: self.last_span
.hi
,
3759 expn_id
: span
.expn_id
,
3761 stmts
.push(P(Spanned
{
3762 node
: StmtSemi(e
, ast
::DUMMY_NODE_ID
),
3763 span
: span_with_semi
,
3766 token
::CloseDelim(token
::Brace
) => *last_block_expr
= Some(e
),
3768 stmts
.push(P(Spanned
{
3769 node
: StmtExpr(e
, ast
::DUMMY_NODE_ID
),
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
>>
3783 if !try
!(self.eat(&token
::Colon
) ){
3784 Ok(OwnedSlice
::empty())
3786 self.parse_ty_param_bounds(mode
)
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
>>
3798 let mut result
= vec
!();
3800 let question_span
= self.span
;
3801 let ate_question
= try
!(self.eat(&token
::Question
));
3803 token
::Lifetime(lifetime
) => {
3805 self.span_err(question_span
,
3806 "`?` may only modify trait bounds, not lifetime bounds");
3808 result
.push(RegionTyParamBound(ast
::Lifetime
{
3809 id
: ast
::DUMMY_NODE_ID
,
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
3821 self.span_err(question_span
,
3823 TraitBoundModifier
::None
3826 TraitBoundModifier
::None
3828 result
.push(TraitTyParamBound(poly_trait_ref
, modifier
))
3833 if !try
!(self.eat(&token
::BinOp(token
::Plus
)) ){
3838 return Ok(OwnedSlice
::from_vec(result
));
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());
3846 let bounds
= try
!(self.parse_colon_then_ty_param_bounds(BoundParsingMode
::Modified
));
3848 let default = if self.check(&token
::Eq
) {
3850 Some(try
!(self.parse_ty_sum()))
3857 id
: ast
::DUMMY_NODE_ID
,
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()`.
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
);
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");
3890 lifetimes
: lifetime_defs
,
3891 ty_params
: ty_params
,
3892 where_clause
: WhereClause
{
3893 id
: ast
::DUMMY_NODE_ID
,
3894 predicates
: Vec
::new(),
3898 Ok(ast_util
::empty_generics())
3902 fn parse_generic_values_after_lt(&mut self) -> PResult
<(Vec
<ast
::Lifetime
>,
3904 Vec
<P
<TypeBinding
>>)> {
3905 let span_lo
= self.span
.lo
;
3906 let lifetimes
= try
!(self.parse_lifetimes(token
::Comma
));
3908 let missing_comma
= !lifetimes
.is_empty() &&
3909 !self.token
.is_like_gt() &&
3911 .as_ref().map_or(true,
3912 |x
| &**x
!= &token
::Comma
);
3916 let msg
= format
!("expected `,` or `>` after lifetime \
3918 self.this_token_to_string());
3919 self.span_err(self.span
, &msg
);
3921 let span_hi
= self.span
.hi
;
3922 let span_hi
= if self.parse_ty_nopanic().is_ok() {
3928 let msg
= format
!("did you mean a single argument type &'a Type, \
3929 or did you mean the comma-separated arguments \
3931 self.span_note(mk_sp(span_lo
, span_hi
), &msg
);
3933 self.abort_if_errors()
3936 // First parse types.
3937 let (types
, returned
) = try
!(self.parse_seq_to_gt_or_return(
3940 try
!(p
.forbid_lifetime());
3941 if p
.look_ahead(1, |t
| t
== &token
::Eq
) {
3944 Ok(Some(try
!(p
.parse_ty_sum())))
3949 // If we found the `>`, don't continue.
3951 return Ok((lifetimes
, types
.into_vec(), Vec
::new()));
3954 // Then parse type bindings.
3955 let bindings
= try
!(self.parse_seq_to_gt(
3958 try
!(p
.forbid_lifetime());
3960 let ident
= try
!(p
.parse_ident());
3961 let found_eq
= try
!(p
.eat(&token
::Eq
));
3964 p
.span_warn(span
, "whoops, no =?");
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
,
3976 Ok((lifetimes
, types
.into_vec(), bindings
.into_vec()))
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"))
3988 /// Parses an optional `where` clause and places it in `generics`.
3991 /// where T : Trait<U, V> + 'b, 'a : 'b
3993 pub fn parse_where_clause(&mut self) -> PResult
<ast
::WhereClause
> {
3994 maybe_whole
!(self, NtWhereClause
);
3996 let mut where_clause
= WhereClause
{
3997 id
: ast
::DUMMY_NODE_ID
,
3998 predicates
: Vec
::new(),
4001 if !try
!(self.eat_keyword(keywords
::Where
)) {
4002 return Ok(where_clause
);
4005 let mut parsed_something
= false;
4007 let lo
= self.span
.lo
;
4009 token
::OpenDelim(token
::Brace
) => {
4013 token
::Lifetime(..) => {
4014 let bounded_lifetime
=
4015 try
!(self.parse_lifetime());
4017 try
!(self.eat(&token
::Colon
));
4020 try
!(self.parse_lifetimes(token
::BinOp(token
::Plus
)));
4022 let hi
= self.last_span
.hi
;
4023 let span
= mk_sp(lo
, hi
);
4025 where_clause
.predicates
.push(ast
::WherePredicate
::RegionPredicate(
4026 ast
::WhereRegionPredicate
{
4028 lifetime
: bounded_lifetime
,
4033 parsed_something
= true;
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());
4047 let bounded_ty
= try
!(self.parse_ty_nopanic());
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
);
4054 if bounds
.is_empty() {
4056 "each predicate in a `where` clause must have \
4057 at least one bound in it");
4060 where_clause
.predicates
.push(ast
::WherePredicate
::BoundPredicate(
4061 ast
::WhereBoundPredicate
{
4063 bound_lifetimes
: bound_lifetimes
,
4064 bounded_ty
: bounded_ty
,
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,
4077 // path: panic!("NYI"), //bounded_ty,
4080 // parsed_something = true;
4083 "equality constraints are not yet supported \
4084 in where clauses (#20041)");
4086 let last_span
= self.last_span
;
4087 self.span_err(last_span
,
4088 "unexpected token in `where` clause");
4093 if !try
!(self.eat(&token
::Comma
) ){
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 \
4108 fn parse_fn_args(&mut self, named_args
: bool
, allow_variadic
: bool
)
4109 -> PResult
<(Vec
<Arg
> , bool
)> {
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
),
4117 if p
.token
== token
::DotDotDot
{
4120 if p
.token
!= token
::CloseDelim(token
::Paren
) {
4122 return Err(p
.span_fatal(span
,
4123 "`...` must be last in argument list for variadic function"))
4127 return Err(p
.span_fatal(span
,
4128 "only foreign functions are allowed to be variadic"))
4132 Ok(Some(try
!(p
.parse_arg_general(named_args
))))
4137 let variadic
= match args
.pop() {
4140 // Need to put back that last arg
4147 if variadic
&& args
.is_empty() {
4149 "variadic function must be declared with at least one named argument");
4152 let args
= args
.into_iter().map(|x
| x
.unwrap()).collect();
4154 Ok((args
, variadic
))
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
>> {
4160 let (args
, variadic
) = try
!(self.parse_fn_args(true, allow_variadic
));
4161 let ret_ty
= try
!(self.parse_ret_ty());
4170 fn is_self_ident(&mut self) -> bool
{
4172 token
::Ident(id
, token
::Plain
) => id
.name
== special_idents
::self_
.name
,
4177 fn expect_self_ident(&mut self) -> PResult
<ast
::Ident
> {
4179 token
::Ident(id
, token
::Plain
) if id
.name
== special_idents
::self_
.name
=> {
4184 let token_str
= self.this_token_to_string();
4185 return Err(self.fatal(&format
!("expected `self`, found `{}`",
4191 fn is_self_type_ident(&mut self) -> bool
{
4193 token
::Ident(id
, token
::Plain
) => id
.name
== special_idents
::type_self
.name
,
4198 fn expect_self_type_ident(&mut self) -> PResult
<ast
::Ident
> {
4200 token
::Ident(id
, token
::Plain
) if id
.name
== special_idents
::type_self
.name
=> {
4205 let token_str
= self.this_token_to_string();
4206 Err(self.fatal(&format
!("expected `Self`, found `{}`",
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
>,
4218 fn maybe_parse_borrowed_explicit_self(this
: &mut Parser
)
4219 -> PResult
<ast
::ExplicitSelf_
> {
4220 // The following things are possible to see here:
4225 // fn(&'lt mut self)
4227 // We already know that the current token is `&`.
4229 if this
.look_ahead(1, |t
| t
.is_keyword(keywords
::SelfValue
)) {
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
)) {
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
)) {
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
)) {
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())))
4254 try
!(self.expect(&token
::OpenDelim(token
::Paren
)));
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
;
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
;
4270 token
::BinOp(token
::Star
) => {
4271 // Possibly "*self" or "*mut self" -- not supported. Try to avoid
4272 // emitting cryptic "unexpected token" errors.
4274 let _mutability
= if self.token
.is_mutability() {
4275 try
!(self.parse_mutability())
4279 if self.is_self_ident() {
4280 let span
= self.span
;
4281 self.span_err(span
, "cannot pass self by raw pointer");
4284 // error case, making bogus self ident:
4285 SelfValue(special_idents
::self_
)
4287 token
::Ident(..) => {
4288 if self.is_self_ident() {
4289 let self_ident
= try
!(self.expect_self_ident());
4291 // Determine whether this is the fully explicit form, `self:
4293 if try
!(self.eat(&token
::Colon
) ){
4294 SelfExplicit(try
!(self.parse_ty_sum()), self_ident
)
4296 SelfValue(self_ident
)
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());
4303 // Determine whether this is the fully explicit form,
4305 if try
!(self.eat(&token
::Colon
) ){
4306 SelfExplicit(try
!(self.parse_ty_sum()), self_ident
)
4308 SelfValue(self_ident
)
4317 let explicit_self_sp
= mk_sp(self_ident_lo
, self_ident_hi
);
4319 // shared fall-through for the three cases below. borrowing prevents simply
4320 // writing this as a closure
4321 macro_rules
! parse_remaining_arguments
{
4324 // If we parsed a self type, expect a comma before the argument list.
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
),
4334 fn_inputs
.insert(0, Arg
::new_self(explicit_self_sp
, mutbl_self
, $self_id
));
4337 token
::CloseDelim(token
::Paren
) => {
4338 vec
!(Arg
::new_self(explicit_self_sp
, mutbl_self
, $self_id
))
4341 let token_str
= self.this_token_to_string();
4342 return Err(self.fatal(&format
!("expected `,` or `)`, found `{}`",
4349 let fn_inputs
= match explicit_self
{
4351 let sep
= seq_sep_trailing_allowed(token
::Comma
);
4352 try
!(self.parse_seq_to_before_end(&token
::CloseDelim(token
::Paren
),
4355 SelfValue(id
) => parse_remaining_arguments
!(id
),
4356 SelfRegion(_
,_
,id
) => parse_remaining_arguments
!(id
),
4357 SelfExplicit(_
,id
) => parse_remaining_arguments
!(id
),
4361 try
!(self.expect(&token
::CloseDelim(token
::Paren
)));
4363 let hi
= self.span
.hi
;
4365 let ret_ty
= try
!(self.parse_ret_ty());
4367 let fn_decl
= P(FnDecl
{
4373 Ok((spanned(lo
, hi
, explicit_self
), fn_decl
))
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
) ){
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()
4393 let output
= try
!(self.parse_ret_ty());
4396 inputs
: inputs_captures
,
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());
4409 fn mk_item(&mut self, lo
: BytePos
, hi
: BytePos
, ident
: Ident
,
4410 node
: Item_
, vis
: Visibility
,
4411 attrs
: Vec
<Attribute
>) -> P
<Item
> {
4415 id
: ast
::DUMMY_NODE_ID
,
4422 /// Parse an item-position function declaration.
4423 fn parse_item_fn(&mut self,
4425 constness
: Constness
,
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
)))
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
))
4441 /// parses all the "front matter" for a `fn` declaration, up to
4442 /// and including the `fn` keyword:
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
)
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
)
4459 (Constness
::NotConst
, unsafety
, abi
)
4461 try
!(self.expect_keyword(keywords
::Fn
));
4462 Ok((constness
, unsafety
, abi
))
4465 /// Parse an impl item.
4466 pub fn parse_impl_item(&mut self) -> PResult
<P
<ImplItem
>> {
4467 maybe_whole
!(no_clone
self, NtImplItem
);
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
))
4488 let (name
, inner_attrs
, node
) = try
!(self.parse_impl_method(vis
));
4489 attrs
.extend(inner_attrs
);
4494 id
: ast
::DUMMY_NODE_ID
,
4495 span
: mk_sp(lo
, self.last_span
.hi
),
4503 fn complain_if_pub_macro(&mut self, visa
: Visibility
, span
: Span
) {
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 \
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
))) {
4524 let last_span
= self.last_span
;
4525 self.complain_if_pub_macro(vis
, last_span
);
4527 let pth
= try
!(self.parse_path(NoTypesAllowed
));
4528 try
!(self.expect(&token
::Not
));
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
),
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
,
4539 if delim
!= token
::Brace
{
4540 try
!(self.expect(&token
::Semi
))
4542 Ok((token
::special_idents
::invalid
, vec
![], ast
::MacImplItem(m
)))
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
| {
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
{
4555 explicit_self
: explicit_self
,
4557 constness
: constness
,
4563 /// Parse trait Foo { ... }
4564 fn parse_item_trait(&mut self, unsafety
: Unsafety
) -> PResult
<ItemInfo
> {
4566 let ident
= try
!(self.parse_ident());
4567 let mut tps
= try
!(self.parse_generics());
4569 // Parse supertrait bounds.
4570 let bounds
= try
!(self.parse_colon_then_ty_param_bounds(BoundParsingMode
::Bare
));
4572 tps
.where_clause
= try
!(self.parse_where_clause());
4574 let meths
= try
!(self.parse_trait_items());
4575 Ok((ident
, ItemTrait(unsafety
, tps
, bounds
, meths
), None
))
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
;
4585 // First, parse type parameters if necessary.
4586 let mut generics
= try
!(self.parse_generics());
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
);
4592 let neg_span
= self.span
;
4593 let polarity
= if try
!(self.eat(&token
::Not
) ){
4594 ast
::ImplPolarity
::Negative
4596 ast
::ImplPolarity
::Positive
4600 let mut ty
= try
!(self.parse_ty_sum());
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.
4606 TyPath(None
, ref path
) => {
4608 path
: (*path
).clone(),
4613 self.span_err(ty
.span
, "not a trait");
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");
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");
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
))
4640 if opt_trait
.is_some() {
4641 ty
= try
!(self.parse_ty_sum());
4643 generics
.where_clause
= try
!(self.parse_where_clause());
4645 try
!(self.expect(&token
::OpenDelim(token
::Brace
)));
4646 let attrs
= self.parse_inner_attributes();
4648 let mut impl_items
= vec
![];
4649 while !try
!(self.eat(&token
::CloseDelim(token
::Brace
))) {
4650 impl_items
.push(try
!(self.parse_impl_item()));
4653 Ok((ast_util
::impl_pretty_name(&opt_trait
, Some(&*ty
)),
4654 ItemImpl(unsafety
, polarity
, generics
, opt_trait
, ty
, impl_items
),
4659 /// Parse a::B<String,i32>
4660 fn parse_trait_ref(&mut self) -> PResult
<TraitRef
> {
4662 path
: try
!(self.parse_path(LifetimeAndTypesWithoutColons
)),
4663 ref_id
: ast
::DUMMY_NODE_ID
,
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());
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());
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
),
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());
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:
4699 // struct Foo<T>(T) where T: Copy;
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.
4706 // Otherwise if we look ahead and see a paren we parse a tuple-style
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
))
4715 // If we see: `struct Foo<T> where T: Copy { ... }`
4716 (try
!(self.parse_record_struct_body(&class_name
)), None
)
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
));
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
))
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
)))
4736 ItemStruct(P(ast
::StructDef
{
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)));
4751 if fields
.is_empty() {
4752 return Err(self.fatal(&format
!("unit-like struct definition should be \
4753 written as `struct {};`",
4759 let token_str
= self.this_token_to_string();
4760 return Err(self.fatal(&format
!("expected `where`, or `{{` after struct \
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
),
4779 let attrs
= p
.parse_outer_attributes();
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()),
4787 Ok(spanned(lo
, p
.span
.hi
, struct_field_
))
4790 if fields
.is_empty() {
4791 return Err(self.fatal(&format
!("unit-like struct definition should be \
4792 written as `struct {};`",
4796 generics
.where_clause
= try
!(self.parse_where_clause());
4797 try
!(self.expect(&token
::Semi
));
4801 /// Parse a structure field declaration
4802 pub fn parse_single_struct_field(&mut self,
4804 attrs
: Vec
<Attribute
> )
4805 -> PResult
<StructField
> {
4806 let a_var
= try
!(self.parse_name_and_ty(vis
, attrs
));
4811 token
::CloseDelim(token
::Brace
) => {}
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 `{}`",
4818 "struct fields should be separated by commas"))
4824 /// Parse an element of a struct definition
4825 fn parse_struct_decl_field(&mut self, allow_pub
: bool
) -> PResult
<StructField
> {
4827 let attrs
= self.parse_outer_attributes();
4829 if try
!(self.eat_keyword(keywords
::Pub
) ){
4831 let span
= self.last_span
;
4832 self.span_err(span
, "`pub` is not allowed here");
4834 return self.parse_single_struct_field(Public
, attrs
);
4837 return self.parse_single_struct_field(Inherited
, attrs
);
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) }
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()) {
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
)));
4858 let hi
= if self.span
== codemap
::DUMMY_SP
{
4865 inner
: mk_sp(inner_lo
, hi
),
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
),
4881 Ok((id
, item
, None
))
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
) {
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
)))
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
)))
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") {
4911 None
=> default_path
,
4913 self.mod_path_stack
.push(file_path
)
4916 fn pop_mod_path(&mut self) {
4917 self.mod_path_stack
.pop().unwrap();
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
))
4924 /// Returns either a path to a module, or .
4925 pub fn default_submod_path(id
: ast
::Ident
, dir_path
: &Path
, codemap
: &CodeMap
) -> ModulePath
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
);
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 {:?}",
4943 dir_path
.display()),
4945 (true, true) => Err(ModulePathError
{
4946 err_msg
: format
!("file for module `{}` found at both {} and {}",
4949 secondary_path_str
),
4950 help_msg
: "delete or rename one of them to remove the ambiguity".to_owned(),
4956 path_exists
: default_exists
|| secondary_exists
,
4961 fn submod_path(&mut self,
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
));
4967 let mut dir_path
= prefix
;
4968 for part
in &self.mod_path_stack
{
4969 dir_path
.push(&**part
);
4972 if let Some(p
) = Parser
::submod_path_from_attr(outer_attrs
, &dir_path
) {
4973 return Ok(ModulePathSuccess { path: p, owns_directory: true }
);
4976 let paths
= Parser
::default_submod_path(id
, &dir_path
, self.sess
.codemap());
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(),
4984 self.span_note(id_sp
,
4985 &format
!("maybe move this module `{0}` to its own directory \
4988 if paths
.path_exists
{
4989 self.span_note(id_sp
,
4990 &format
!("... or maybe `use` the module `{}` instead \
4991 of possibly redeclaring it",
4994 self.abort_if_errors();
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
)),
5003 /// Read a module from a source file.
5004 fn eval_src_mod(&mut self,
5006 outer_attrs
: &[ast
::Attribute
],
5008 -> PResult
<(ast
::Item_
, Vec
<ast
::Attribute
> )> {
5009 let ModulePathSuccess { path, owns_directory }
= try
!(self.submod_path(id
,
5013 self.eval_src_mod_from_path(path
,
5019 fn eval_src_mod_from_path(&mut self,
5021 owns_directory
: bool
,
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
) {
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(" -> ");
5033 err
.push_str(&path
.to_string_lossy());
5034 return Err(self.span_fatal(id_sp
, &err
[..]));
5038 included_mod_stack
.push(path
.clone());
5039 drop(included_mod_stack
);
5041 let mut p0
= new_sub_parser_from_file(self.sess
,
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
))
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
));
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
{
5068 node
: ForeignItemFn(decl
, generics
),
5069 id
: ast
::DUMMY_NODE_ID
,
5070 span
: mk_sp(lo
, hi
),
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
;
5080 try
!(self.expect_keyword(keywords
::Static
));
5081 let mutbl
= try
!(self.eat_keyword(keywords
::Mut
));
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
));
5091 node
: ForeignItemStatic(ty
, mutbl
),
5092 id
: ast
::DUMMY_NODE_ID
,
5093 span
: mk_sp(lo
, hi
),
5098 /// Parse extern crate links
5102 /// extern crate foo;
5103 /// extern crate bar as foo;
5104 fn parse_item_extern_crate(&mut self,
5106 visibility
: Visibility
,
5107 attrs
: Vec
<Attribute
>)
5108 -> PResult
<P
<Item
>> {
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
)
5116 try
!(self.expect(&token
::Semi
));
5118 let last_span
= self.last_span
;
5120 if visibility
== ast
::Public
{
5121 self.span_warn(mk_sp(lo
, last_span
.hi
),
5122 "`pub extern crate` does not work as expected and should not be used. \
5123 Likely to become an error. Prefer `extern crate` and `pub use`.");
5129 ItemExternCrate(maybe_path
),
5134 /// Parse `extern` for foreign ABIs
5137 /// `extern` is expected to have been
5138 /// consumed before calling this method
5144 fn parse_item_foreign_mod(&mut self,
5146 opt_abi
: Option
<abi
::Abi
>,
5147 visibility
: Visibility
,
5148 mut attrs
: Vec
<Attribute
>)
5149 -> PResult
<P
<Item
>> {
5150 try
!(self.expect(&token
::OpenDelim(token
::Brace
)));
5152 let abi
= opt_abi
.unwrap_or(abi
::C
);
5154 attrs
.extend(self.parse_inner_attributes());
5156 let mut foreign_items
= vec
![];
5157 while let Some(item
) = try
!(self.parse_foreign_item()) {
5158 foreign_items
.push(item
);
5160 try
!(self.expect(&token
::CloseDelim(token
::Brace
)));
5162 let last_span
= self.last_span
;
5163 let m
= ast
::ForeignMod
{
5165 items
: foreign_items
5169 special_idents
::invalid
,
5175 /// Parse type Foo = Bar;
5176 fn parse_item_type(&mut self) -> PResult
<ItemInfo
> {
5177 let ident
= try
!(self.parse_ident());
5178 let mut tps
= try
!(self.parse_generics());
5179 tps
.where_clause
= try
!(self.parse_where_clause());
5180 try
!(self.expect(&token
::Eq
));
5181 let ty
= try
!(self.parse_ty_sum());
5182 try
!(self.expect(&token
::Semi
));
5183 Ok((ident
, ItemTy(ty
, tps
), None
))
5186 /// Parse a structure-like enum variant definition
5187 /// this should probably be renamed or refactored...
5188 fn parse_struct_def(&mut self) -> PResult
<P
<StructDef
>> {
5189 let mut fields
: Vec
<StructField
> = Vec
::new();
5190 while self.token
!= token
::CloseDelim(token
::Brace
) {
5191 fields
.push(try
!(self.parse_struct_decl_field(false)));
5201 /// Parse the part of an "enum" decl following the '{'
5202 fn parse_enum_def(&mut self, _generics
: &ast
::Generics
) -> PResult
<EnumDef
> {
5203 let mut variants
= Vec
::new();
5204 let mut all_nullary
= true;
5205 let mut any_disr
= None
;
5206 while self.token
!= token
::CloseDelim(token
::Brace
) {
5207 let variant_attrs
= self.parse_outer_attributes();
5208 let vlo
= self.span
.lo
;
5210 let vis
= try
!(self.parse_visibility());
5214 let mut args
= Vec
::new();
5215 let mut disr_expr
= None
;
5216 ident
= try
!(self.parse_ident());
5217 if try
!(self.eat(&token
::OpenDelim(token
::Brace
)) ){
5218 // Parse a struct variant.
5219 all_nullary
= false;
5220 let start_span
= self.span
;
5221 let struct_def
= try
!(self.parse_struct_def());
5222 if struct_def
.fields
.is_empty() {
5223 self.span_err(start_span
,
5224 &format
!("unit-like struct variant should be written \
5225 without braces, as `{},`",
5228 kind
= StructVariantKind(struct_def
);
5229 } else if self.check(&token
::OpenDelim(token
::Paren
)) {
5230 all_nullary
= false;
5231 let arg_tys
= try
!(self.parse_enum_variant_seq(
5232 &token
::OpenDelim(token
::Paren
),
5233 &token
::CloseDelim(token
::Paren
),
5234 seq_sep_trailing_allowed(token
::Comma
),
5235 |p
| p
.parse_ty_sum()
5238 args
.push(ast
::VariantArg
{
5240 id
: ast
::DUMMY_NODE_ID
,
5243 kind
= TupleVariantKind(args
);
5244 } else if try
!(self.eat(&token
::Eq
) ){
5245 disr_expr
= Some(try
!(self.parse_expr_nopanic()));
5246 any_disr
= disr_expr
.as_ref().map(|expr
| expr
.span
);
5247 kind
= TupleVariantKind(args
);
5249 kind
= TupleVariantKind(Vec
::new());
5252 let vr
= ast
::Variant_
{
5254 attrs
: variant_attrs
,
5256 id
: ast
::DUMMY_NODE_ID
,
5257 disr_expr
: disr_expr
,
5260 variants
.push(P(spanned(vlo
, self.last_span
.hi
, vr
)));
5262 if !try
!(self.eat(&token
::Comma
)) { break; }
5264 try
!(self.expect(&token
::CloseDelim(token
::Brace
)));
5266 Some(disr_span
) if !all_nullary
=>
5267 self.span_err(disr_span
,
5268 "discriminator values can only be used with a c-like enum"),
5272 Ok(ast
::EnumDef { variants: variants }
)
5275 /// Parse an "enum" declaration
5276 fn parse_item_enum(&mut self) -> PResult
<ItemInfo
> {
5277 let id
= try
!(self.parse_ident());
5278 let mut generics
= try
!(self.parse_generics());
5279 generics
.where_clause
= try
!(self.parse_where_clause());
5280 try
!(self.expect(&token
::OpenDelim(token
::Brace
)));
5282 let enum_definition
= try
!(self.parse_enum_def(&generics
));
5283 Ok((id
, ItemEnum(enum_definition
, generics
), None
))
5286 /// Parses a string as an ABI spec on an extern type or module. Consumes
5287 /// the `extern` keyword, if one is found.
5288 fn parse_opt_abi(&mut self) -> PResult
<Option
<abi
::Abi
>> {
5290 token
::Literal(token
::Str_(s
), suf
) | token
::Literal(token
::StrRaw(s
, _
), suf
) => {
5292 self.expect_no_suffix(sp
, "ABI spec", suf
);
5294 match abi
::lookup(&s
.as_str()) {
5295 Some(abi
) => Ok(Some(abi
)),
5297 let last_span
= self.last_span
;
5300 &format
!("invalid ABI: expected one of [{}], \
5302 abi
::all_names().join(", "),
5313 /// Parse one of the items allowed by the flags.
5314 /// NB: this function no longer parses the items inside an
5316 fn parse_item_(&mut self, attrs
: Vec
<Attribute
>,
5317 macros_allowed
: bool
) -> PResult
<Option
<P
<Item
>>> {
5318 let nt_item
= match self.token
{
5319 token
::Interpolated(token
::NtItem(ref item
)) => {
5320 Some((**item
).clone())
5327 let mut attrs
= attrs
;
5328 mem
::swap(&mut item
.attrs
, &mut attrs
);
5329 item
.attrs
.extend(attrs
);
5330 return Ok(Some(P(item
)));
5335 let lo
= self.span
.lo
;
5337 let visibility
= try
!(self.parse_visibility());
5339 if try
!(self.eat_keyword(keywords
::Use
) ){
5341 let item_
= ItemUse(try
!(self.parse_view_path()));
5342 try
!(self.expect(&token
::Semi
));
5344 let last_span
= self.last_span
;
5345 let item
= self.mk_item(lo
,
5347 token
::special_idents
::invalid
,
5351 return Ok(Some(item
));
5354 if try
!(self.eat_keyword(keywords
::Extern
)) {
5355 if try
!(self.eat_keyword(keywords
::Crate
)) {
5356 return Ok(Some(try
!(self.parse_item_extern_crate(lo
, visibility
, attrs
))));
5359 let opt_abi
= try
!(self.parse_opt_abi());
5361 if try
!(self.eat_keyword(keywords
::Fn
) ){
5362 // EXTERN FUNCTION ITEM
5363 let abi
= opt_abi
.unwrap_or(abi
::C
);
5364 let (ident
, item_
, extra_attrs
) =
5365 try
!(self.parse_item_fn(Unsafety
::Normal
, Constness
::NotConst
, abi
));
5366 let last_span
= self.last_span
;
5367 let item
= self.mk_item(lo
,
5372 maybe_append(attrs
, extra_attrs
));
5373 return Ok(Some(item
));
5374 } else if self.check(&token
::OpenDelim(token
::Brace
)) {
5375 return Ok(Some(try
!(self.parse_item_foreign_mod(lo
, opt_abi
, visibility
, attrs
))));
5378 try
!(self.expect_one_of(&[], &[]));
5381 if try
!(self.eat_keyword(keywords
::Static
) ){
5383 let m
= if try
!(self.eat_keyword(keywords
::Mut
)) {MutMutable}
else {MutImmutable}
;
5384 let (ident
, item_
, extra_attrs
) = try
!(self.parse_item_const(Some(m
)));
5385 let last_span
= self.last_span
;
5386 let item
= self.mk_item(lo
,
5391 maybe_append(attrs
, extra_attrs
));
5392 return Ok(Some(item
));
5394 if try
!(self.eat_keyword(keywords
::Const
) ){
5395 if self.check_keyword(keywords
::Fn
) {
5396 // CONST FUNCTION ITEM
5398 let (ident
, item_
, extra_attrs
) =
5399 try
!(self.parse_item_fn(Unsafety
::Normal
, Constness
::Const
, abi
::Rust
));
5400 let last_span
= self.last_span
;
5401 let item
= self.mk_item(lo
,
5406 maybe_append(attrs
, extra_attrs
));
5407 return Ok(Some(item
));
5411 if try
!(self.eat_keyword(keywords
::Mut
) ){
5412 let last_span
= self.last_span
;
5413 self.span_err(last_span
, "const globals cannot be mutable");
5414 self.fileline_help(last_span
, "did you mean to declare a static?");
5416 let (ident
, item_
, extra_attrs
) = try
!(self.parse_item_const(None
));
5417 let last_span
= self.last_span
;
5418 let item
= self.mk_item(lo
,
5423 maybe_append(attrs
, extra_attrs
));
5424 return Ok(Some(item
));
5426 if self.check_keyword(keywords
::Unsafe
) &&
5427 self.look_ahead(1, |t
| t
.is_keyword(keywords
::Trait
))
5429 // UNSAFE TRAIT ITEM
5430 try
!(self.expect_keyword(keywords
::Unsafe
));
5431 try
!(self.expect_keyword(keywords
::Trait
));
5432 let (ident
, item_
, extra_attrs
) =
5433 try
!(self.parse_item_trait(ast
::Unsafety
::Unsafe
));
5434 let last_span
= self.last_span
;
5435 let item
= self.mk_item(lo
,
5440 maybe_append(attrs
, extra_attrs
));
5441 return Ok(Some(item
));
5443 if self.check_keyword(keywords
::Unsafe
) &&
5444 self.look_ahead(1, |t
| t
.is_keyword(keywords
::Impl
))
5447 try
!(self.expect_keyword(keywords
::Unsafe
));
5448 try
!(self.expect_keyword(keywords
::Impl
));
5449 let (ident
, item_
, extra_attrs
) = try
!(self.parse_item_impl(ast
::Unsafety
::Unsafe
));
5450 let last_span
= self.last_span
;
5451 let item
= self.mk_item(lo
,
5456 maybe_append(attrs
, extra_attrs
));
5457 return Ok(Some(item
));
5459 if self.check_keyword(keywords
::Fn
) {
5462 let (ident
, item_
, extra_attrs
) =
5463 try
!(self.parse_item_fn(Unsafety
::Normal
, Constness
::NotConst
, abi
::Rust
));
5464 let last_span
= self.last_span
;
5465 let item
= self.mk_item(lo
,
5470 maybe_append(attrs
, extra_attrs
));
5471 return Ok(Some(item
));
5473 if self.check_keyword(keywords
::Unsafe
)
5474 && self.look_ahead(1, |t
| *t
!= token
::OpenDelim(token
::Brace
)) {
5475 // UNSAFE FUNCTION ITEM
5477 let abi
= if try
!(self.eat_keyword(keywords
::Extern
) ){
5478 try
!(self.parse_opt_abi()).unwrap_or(abi
::C
)
5482 try
!(self.expect_keyword(keywords
::Fn
));
5483 let (ident
, item_
, extra_attrs
) =
5484 try
!(self.parse_item_fn(Unsafety
::Unsafe
, Constness
::NotConst
, abi
));
5485 let last_span
= self.last_span
;
5486 let item
= self.mk_item(lo
,
5491 maybe_append(attrs
, extra_attrs
));
5492 return Ok(Some(item
));
5494 if try
!(self.eat_keyword(keywords
::Mod
) ){
5496 let (ident
, item_
, extra_attrs
) =
5497 try
!(self.parse_item_mod(&attrs
[..]));
5498 let last_span
= self.last_span
;
5499 let item
= self.mk_item(lo
,
5504 maybe_append(attrs
, extra_attrs
));
5505 return Ok(Some(item
));
5507 if try
!(self.eat_keyword(keywords
::Type
) ){
5509 let (ident
, item_
, extra_attrs
) = try
!(self.parse_item_type());
5510 let last_span
= self.last_span
;
5511 let item
= self.mk_item(lo
,
5516 maybe_append(attrs
, extra_attrs
));
5517 return Ok(Some(item
));
5519 if try
!(self.eat_keyword(keywords
::Enum
) ){
5521 let (ident
, item_
, extra_attrs
) = try
!(self.parse_item_enum());
5522 let last_span
= self.last_span
;
5523 let item
= self.mk_item(lo
,
5528 maybe_append(attrs
, extra_attrs
));
5529 return Ok(Some(item
));
5531 if try
!(self.eat_keyword(keywords
::Trait
) ){
5533 let (ident
, item_
, extra_attrs
) =
5534 try
!(self.parse_item_trait(ast
::Unsafety
::Normal
));
5535 let last_span
= self.last_span
;
5536 let item
= self.mk_item(lo
,
5541 maybe_append(attrs
, extra_attrs
));
5542 return Ok(Some(item
));
5544 if try
!(self.eat_keyword(keywords
::Impl
) ){
5546 let (ident
, item_
, extra_attrs
) = try
!(self.parse_item_impl(ast
::Unsafety
::Normal
));
5547 let last_span
= self.last_span
;
5548 let item
= self.mk_item(lo
,
5553 maybe_append(attrs
, extra_attrs
));
5554 return Ok(Some(item
));
5556 if try
!(self.eat_keyword(keywords
::Struct
) ){
5558 let (ident
, item_
, extra_attrs
) = try
!(self.parse_item_struct());
5559 let last_span
= self.last_span
;
5560 let item
= self.mk_item(lo
,
5565 maybe_append(attrs
, extra_attrs
));
5566 return Ok(Some(item
));
5568 self.parse_macro_use_or_failure(attrs
,macros_allowed
,lo
,visibility
)
5571 /// Parse a foreign item.
5572 fn parse_foreign_item(&mut self) -> PResult
<Option
<P
<ForeignItem
>>> {
5573 let attrs
= self.parse_outer_attributes();
5574 let lo
= self.span
.lo
;
5575 let visibility
= try
!(self.parse_visibility());
5577 if self.check_keyword(keywords
::Static
) {
5578 // FOREIGN STATIC ITEM
5579 return Ok(Some(try
!(self.parse_item_foreign_static(visibility
, attrs
))));
5581 if self.check_keyword(keywords
::Fn
) || self.check_keyword(keywords
::Unsafe
) {
5582 // FOREIGN FUNCTION ITEM
5583 return Ok(Some(try
!(self.parse_item_foreign_fn(visibility
, attrs
))));
5586 // FIXME #5668: this will occur for a macro invocation:
5587 match try
!(self.parse_macro_use_or_failure(attrs
, true, lo
, visibility
)) {
5589 return Err(self.span_fatal(item
.span
, "macros cannot expand to foreign items"));
5595 /// This is the fall-through for parsing items.
5596 fn parse_macro_use_or_failure(
5598 attrs
: Vec
<Attribute
> ,
5599 macros_allowed
: bool
,
5601 visibility
: Visibility
5602 ) -> PResult
<Option
<P
<Item
>>> {
5603 if macros_allowed
&& !self.token
.is_any_keyword()
5604 && self.look_ahead(1, |t
| *t
== token
::Not
)
5605 && (self.look_ahead(2, |t
| t
.is_plain_ident())
5606 || self.look_ahead(2, |t
| *t
== token
::OpenDelim(token
::Paren
))
5607 || self.look_ahead(2, |t
| *t
== token
::OpenDelim(token
::Brace
))) {
5608 // MACRO INVOCATION ITEM
5610 let last_span
= self.last_span
;
5611 self.complain_if_pub_macro(visibility
, last_span
);
5614 let pth
= try
!(self.parse_path(NoTypesAllowed
));
5615 try
!(self.expect(&token
::Not
));
5617 // a 'special' identifier (like what `macro_rules!` uses)
5618 // is optional. We should eventually unify invoc syntax
5620 let id
= if self.token
.is_plain_ident() {
5621 try
!(self.parse_ident())
5623 token
::special_idents
::invalid
// no special identifier
5625 // eat a matched-delimiter token tree:
5626 let delim
= try
!(self.expect_open_delim());
5627 let tts
= try
!(self.parse_seq_to_end(&token
::CloseDelim(delim
),
5629 |p
| p
.parse_token_tree()));
5630 // single-variant-enum... :
5631 let m
= ast
::MacInvocTT(pth
, tts
, EMPTY_CTXT
);
5632 let m
: ast
::Mac
= codemap
::Spanned
{ node
: m
,
5633 span
: mk_sp(self.span
.lo
,
5636 if delim
!= token
::Brace
{
5637 if !try
!(self.eat(&token
::Semi
) ){
5638 let last_span
= self.last_span
;
5639 self.span_err(last_span
,
5640 "macros that expand to items must either \
5641 be surrounded with braces or followed by \
5646 let item_
= ItemMac(m
);
5647 let last_span
= self.last_span
;
5648 let item
= self.mk_item(lo
,
5654 return Ok(Some(item
));
5657 // FAILURE TO PARSE ITEM
5661 let last_span
= self.last_span
;
5662 return Err(self.span_fatal(last_span
, "unmatched visibility `pub`"));
5666 if !attrs
.is_empty() {
5667 self.expected_item_err(&attrs
);
5672 pub fn parse_item_nopanic(&mut self) -> PResult
<Option
<P
<Item
>>> {
5673 let attrs
= self.parse_outer_attributes();
5674 self.parse_item_(attrs
, true)
5678 /// Matches view_path : MOD? non_global_path as IDENT
5679 /// | MOD? non_global_path MOD_SEP LBRACE RBRACE
5680 /// | MOD? non_global_path MOD_SEP LBRACE ident_seq RBRACE
5681 /// | MOD? non_global_path MOD_SEP STAR
5682 /// | MOD? non_global_path
5683 fn parse_view_path(&mut self) -> PResult
<P
<ViewPath
>> {
5684 let lo
= self.span
.lo
;
5686 // Allow a leading :: because the paths are absolute either way.
5687 // This occurs with "use $crate::..." in macros.
5688 try
!(self.eat(&token
::ModSep
));
5690 if self.check(&token
::OpenDelim(token
::Brace
)) {
5692 let idents
= try
!(self.parse_unspanned_seq(
5693 &token
::OpenDelim(token
::Brace
),
5694 &token
::CloseDelim(token
::Brace
),
5695 seq_sep_trailing_allowed(token
::Comma
),
5696 |p
| p
.parse_path_list_item()));
5697 let path
= ast
::Path
{
5698 span
: mk_sp(lo
, self.span
.hi
),
5700 segments
: Vec
::new()
5702 return Ok(P(spanned(lo
, self.span
.hi
, ViewPathList(path
, idents
))));
5705 let first_ident
= try
!(self.parse_ident());
5706 let mut path
= vec
!(first_ident
);
5707 if let token
::ModSep
= self.token
{
5708 // foo::bar or foo::{a,b,c} or foo::*
5709 while self.check(&token
::ModSep
) {
5713 token
::Ident(..) => {
5714 let ident
= try
!(self.parse_ident());
5718 // foo::bar::{a,b,c}
5719 token
::OpenDelim(token
::Brace
) => {
5720 let idents
= try
!(self.parse_unspanned_seq(
5721 &token
::OpenDelim(token
::Brace
),
5722 &token
::CloseDelim(token
::Brace
),
5723 seq_sep_trailing_allowed(token
::Comma
),
5724 |p
| p
.parse_path_list_item()
5726 let path
= ast
::Path
{
5727 span
: mk_sp(lo
, self.span
.hi
),
5729 segments
: path
.into_iter().map(|identifier
| {
5731 identifier
: identifier
,
5732 parameters
: ast
::PathParameters
::none(),
5736 return Ok(P(spanned(lo
, self.span
.hi
, ViewPathList(path
, idents
))));
5740 token
::BinOp(token
::Star
) => {
5742 let path
= ast
::Path
{
5743 span
: mk_sp(lo
, self.span
.hi
),
5745 segments
: path
.into_iter().map(|identifier
| {
5747 identifier
: identifier
,
5748 parameters
: ast
::PathParameters
::none(),
5752 return Ok(P(spanned(lo
, self.span
.hi
, ViewPathGlob(path
))));
5755 // fall-through for case foo::bar::;
5757 self.span_err(self.span
, "expected identifier or `{` or `*`, found `;`");
5764 let mut rename_to
= path
[path
.len() - 1];
5765 let path
= ast
::Path
{
5766 span
: mk_sp(lo
, self.last_span
.hi
),
5768 segments
: path
.into_iter().map(|identifier
| {
5770 identifier
: identifier
,
5771 parameters
: ast
::PathParameters
::none(),
5775 rename_to
= try
!(self.parse_rename()).unwrap_or(rename_to
);
5776 Ok(P(spanned(lo
, self.last_span
.hi
, ViewPathSimple(rename_to
, path
))))
5779 fn parse_rename(&mut self) -> PResult
<Option
<Ident
>> {
5780 if try
!(self.eat_keyword(keywords
::As
)) {
5781 self.parse_ident().map(Some
)
5787 /// Parses a source module as a crate. This is the main
5788 /// entry point for the parser.
5789 pub fn parse_crate_mod(&mut self) -> PResult
<Crate
> {
5790 let lo
= self.span
.lo
;
5792 attrs
: self.parse_inner_attributes(),
5793 module
: try
!(self.parse_mod_items(&token
::Eof
, lo
)),
5794 config
: self.cfg
.clone(),
5795 span
: mk_sp(lo
, self.span
.lo
),
5796 exported_macros
: Vec
::new(),
5800 pub fn parse_optional_str(&mut self)
5801 -> PResult
<Option
<(InternedString
,
5803 Option
<ast
::Name
>)>> {
5804 let ret
= match self.token
{
5805 token
::Literal(token
::Str_(s
), suf
) => {
5806 (self.id_to_interned_str(s
.ident()), ast
::CookedStr
, suf
)
5808 token
::Literal(token
::StrRaw(s
, n
), suf
) => {
5809 (self.id_to_interned_str(s
.ident()), ast
::RawStr(n
), suf
)
5811 _
=> return Ok(None
)
5817 pub fn parse_str(&mut self) -> PResult
<(InternedString
, StrStyle
)> {
5818 match try
!(self.parse_optional_str()) {
5819 Some((s
, style
, suf
)) => {
5820 let sp
= self.last_span
;
5821 self.expect_no_suffix(sp
, "string literal", suf
);
5824 _
=> Err(self.fatal("expected string literal"))