src/libsyntax/ast.rs

   1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // The Rust abstract syntax tree.
  12
  13 pub use self::AsmDialect::*;
  14 pub use self::AttrStyle::*;
  15 pub use self::BindingMode::*;
  16 pub use self::BinOp_::*;
  17 pub use self::BlockCheckMode::*;
  18 pub use self::CaptureClause::*;
  19 pub use self::Decl_::*;
  20 pub use self::ExplicitSelf_::*;
  21 pub use self::Expr_::*;
  22 pub use self::FloatTy::*;
  23 pub use self::FunctionRetTy::*;
  24 pub use self::ForeignItem_::*;
  25 pub use self::ImplItem_::*;
  26 pub use self::InlinedItem::*;
  27 pub use self::IntTy::*;
  28 pub use self::Item_::*;
  29 pub use self::KleeneOp::*;
  30 pub use self::Lit_::*;
  31 pub use self::LitIntType::*;
  32 pub use self::Mac_::*;
  33 pub use self::MacStmtStyle::*;
  34 pub use self::MetaItem_::*;
  35 pub use self::Mutability::*;
  36 pub use self::Pat_::*;
  37 pub use self::PathListItem_::*;
  38 pub use self::PatWildKind::*;
  39 pub use self::PrimTy::*;
  40 pub use self::Sign::*;
  41 pub use self::Stmt_::*;
  42 pub use self::StrStyle::*;
  43 pub use self::StructFieldKind::*;
  44 pub use self::TokenTree::*;
  45 pub use self::TraitItem_::*;
  46 pub use self::Ty_::*;
  47 pub use self::TyParamBound::*;
  48 pub use self::UintTy::*;
  49 pub use self::UnOp::*;
  50 pub use self::UnsafeSource::*;
  51 pub use self::VariantKind::*;
  52 pub use self::ViewPath_::*;
  53 pub use self::Visibility::*;
  54 pub use self::PathParameters::*;
  55
  56 use codemap::{Span, Spanned, DUMMY_SP, ExpnId};
  57 use abi::Abi;
  58 use ast_util;
  59 use ext::base;
  60 use ext::tt::macro_parser;
  61 use owned_slice::OwnedSlice;
  62 use parse::token::{InternedString, str_to_ident};
  63 use parse::token;
  64 use parse::lexer;
  65 use parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
  66 use print::pprust;
  67 use ptr::P;
  68
  69 use std::cell::Cell;
  70 use std::fmt;
  71 use std::rc::Rc;
  72 use serialize::{Encodable, Decodable, Encoder, Decoder};
  73
  74 // FIXME #6993: in librustc, uses of "ident" should be replaced
  75 // by just "Name".
  76
  77 /// An identifier contains a Name (index into the interner
  78 /// table) and a SyntaxContext to track renaming and
  79 /// macro expansion per Flatt et al., "Macros
  80 /// That Work Together"
  81 #[derive(Clone, Copy, Hash, PartialOrd, Eq, Ord)]
  82 pub struct Ident {
  83     pub name: Name,
  84     pub ctxt: SyntaxContext
  85 }
  86
  87 impl Ident {
  88     /// Construct an identifier with the given name and an empty context:
  89     pub fn new(name: Name) -> Ident { Ident {name: name, ctxt: EMPTY_CTXT}}
  90 }
  91
  92 impl fmt::Debug for Ident {
  93     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  94         write!(f, "{}#{}", self.name, self.ctxt)
  95     }
  96 }
  97
  98 impl fmt::Display for Ident {
  99     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 100         fmt::Display::fmt(&self.name, f)
 101     }
 102 }
 103
 104 impl fmt::Debug for Name {
 105     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 106         let Name(nm) = *self;
 107         write!(f, "{}({})", self, nm)
 108     }
 109 }
 110
 111 impl fmt::Display for Name {
 112     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 113         fmt::Display::fmt(&self.as_str(), f)
 114     }
 115 }
 116
 117 impl PartialEq for Ident {
 118     fn eq(&self, other: &Ident) -> bool {
 119         if self.ctxt == other.ctxt {
 120             self.name == other.name
 121         } else {
 122             // IF YOU SEE ONE OF THESE FAILS: it means that you're comparing
 123             // idents that have different contexts. You can't fix this without
 124             // knowing whether the comparison should be hygienic or non-hygienic.
 125             // if it should be non-hygienic (most things are), just compare the
 126             // 'name' fields of the idents. Or, even better, replace the idents
 127             // with Name's.
 128             //
 129             // On the other hand, if the comparison does need to be hygienic,
 130             // one example and its non-hygienic counterpart would be:
 131             //      syntax::parse::token::Token::mtwt_eq
 132             //      syntax::ext::tt::macro_parser::token_name_eq
 133             panic!("not allowed to compare these idents: {:?}, {:?}. \
 134                    Probably related to issue \\#6993", self, other);
 135         }
 136     }
 137 }
 138
 139 /// A SyntaxContext represents a chain of macro-expandings
 140 /// and renamings. Each macro expansion corresponds to
 141 /// a fresh u32
 142
 143 // I'm representing this syntax context as an index into
 144 // a table, in order to work around a compiler bug
 145 // that's causing unreleased memory to cause core dumps
 146 // and also perhaps to save some work in destructor checks.
 147 // the special uint '0' will be used to indicate an empty
 148 // syntax context.
 149
 150 // this uint is a reference to a table stored in thread-local
 151 // storage.
 152 pub type SyntaxContext = u32;
 153 pub const EMPTY_CTXT : SyntaxContext = 0;
 154 pub const ILLEGAL_CTXT : SyntaxContext = 1;
 155
 156 /// A name is a part of an identifier, representing a string or gensym. It's
 157 /// the result of interning.
 158 #[derive(Eq, Ord, PartialEq, PartialOrd, Hash,
 159            RustcEncodable, RustcDecodable, Clone, Copy)]
 160 pub struct Name(pub u32);
 161
 162 impl<T: AsRef<str>> PartialEq<T> for Name {
 163     fn eq(&self, other: &T) -> bool {
 164         self.as_str() == other.as_ref()
 165     }
 166 }
 167
 168 impl Name {
 169     pub fn as_str(&self) -> token::InternedString {
 170         token::InternedString::new_from_name(*self)
 171     }
 172
 173     pub fn usize(&self) -> usize {
 174         let Name(nm) = *self;
 175         nm as usize
 176     }
 177
 178     pub fn ident(&self) -> Ident {
 179         Ident { name: *self, ctxt: 0 }
 180     }
 181 }
 182
 183 /// A mark represents a unique id associated with a macro expansion
 184 pub type Mrk = u32;
 185
 186 impl Encodable for Ident {
 187     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
 188         s.emit_str(&self.name.as_str())
 189     }
 190 }
 191
 192 impl Decodable for Ident {
 193     fn decode<D: Decoder>(d: &mut D) -> Result<Ident, D::Error> {
 194         Ok(str_to_ident(&try!(d.read_str())[..]))
 195     }
 196 }
 197
 198 /// Function name (not all functions have names)
 199 pub type FnIdent = Option<Ident>;
 200
 201 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
 202 pub struct Lifetime {
 203     pub id: NodeId,
 204     pub span: Span,
 205     pub name: Name
 206 }
 207
 208 impl fmt::Debug for Lifetime {
 209     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 210         write!(f, "lifetime({}: {})", self.id, pprust::lifetime_to_string(self))
 211     }
 212 }
 213
 214 /// A lifetime definition, eg `'a: 'b+'c+'d`
 215 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 216 pub struct LifetimeDef {
 217     pub lifetime: Lifetime,
 218     pub bounds: Vec<Lifetime>
 219 }
 220
 221 /// A "Path" is essentially Rust's notion of a name; for instance:
 222 /// std::cmp::PartialEq  .  It's represented as a sequence of identifiers,
 223 /// along with a bunch of supporting information.
 224 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
 225 pub struct Path {
 226     pub span: Span,
 227     /// A `::foo` path, is relative to the crate root rather than current
 228     /// module (like paths in an import).
 229     pub global: bool,
 230     /// The segments in the path: the things separated by `::`.
 231     pub segments: Vec<PathSegment>,
 232 }
 233
 234 impl fmt::Debug for Path {
 235     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 236         write!(f, "path({})", pprust::path_to_string(self))
 237     }
 238 }
 239
 240 impl fmt::Display for Path {
 241     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 242         write!(f, "{}", pprust::path_to_string(self))
 243     }
 244 }
 245
 246 /// A segment of a path: an identifier, an optional lifetime, and a set of
 247 /// types.
 248 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 249 pub struct PathSegment {
 250     /// The identifier portion of this path segment.
 251     pub identifier: Ident,
 252
 253     /// Type/lifetime parameters attached to this path. They come in
 254     /// two flavors: `Path<A,B,C>` and `Path(A,B) -> C`. Note that
 255     /// this is more than just simple syntactic sugar; the use of
 256     /// parens affects the region binding rules, so we preserve the
 257     /// distinction.
 258     pub parameters: PathParameters,
 259 }
 260
 261 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 262 pub enum PathParameters {
 263     /// The `<'a, A,B,C>` in `foo::bar::baz::<'a, A,B,C>`
 264     AngleBracketedParameters(AngleBracketedParameterData),
 265     /// The `(A,B)` and `C` in `Foo(A,B) -> C`
 266     ParenthesizedParameters(ParenthesizedParameterData),
 267 }
 268
 269 impl PathParameters {
 270     pub fn none() -> PathParameters {
 271         AngleBracketedParameters(AngleBracketedParameterData {
 272             lifetimes: Vec::new(),
 273             types: OwnedSlice::empty(),
 274             bindings: OwnedSlice::empty(),
 275         })
 276     }
 277
 278     pub fn is_empty(&self) -> bool {
 279         match *self {
 280             AngleBracketedParameters(ref data) => data.is_empty(),
 281
 282             // Even if the user supplied no types, something like
 283             // `X()` is equivalent to `X<(),()>`.
 284             ParenthesizedParameters(..) => false,
 285         }
 286     }
 287
 288     pub fn has_lifetimes(&self) -> bool {
 289         match *self {
 290             AngleBracketedParameters(ref data) => !data.lifetimes.is_empty(),
 291             ParenthesizedParameters(_) => false,
 292         }
 293     }
 294
 295     pub fn has_types(&self) -> bool {
 296         match *self {
 297             AngleBracketedParameters(ref data) => !data.types.is_empty(),
 298             ParenthesizedParameters(..) => true,
 299         }
 300     }
 301
 302     /// Returns the types that the user wrote. Note that these do not necessarily map to the type
 303     /// parameters in the parenthesized case.
 304     pub fn types(&self) -> Vec<&P<Ty>> {
 305         match *self {
 306             AngleBracketedParameters(ref data) => {
 307                 data.types.iter().collect()
 308             }
 309             ParenthesizedParameters(ref data) => {
 310                 data.inputs.iter()
 311                     .chain(data.output.iter())
 312                     .collect()
 313             }
 314         }
 315     }
 316
 317     pub fn lifetimes(&self) -> Vec<&Lifetime> {
 318         match *self {
 319             AngleBracketedParameters(ref data) => {
 320                 data.lifetimes.iter().collect()
 321             }
 322             ParenthesizedParameters(_) => {
 323                 Vec::new()
 324             }
 325         }
 326     }
 327
 328     pub fn bindings(&self) -> Vec<&P<TypeBinding>> {
 329         match *self {
 330             AngleBracketedParameters(ref data) => {
 331                 data.bindings.iter().collect()
 332             }
 333             ParenthesizedParameters(_) => {
 334                 Vec::new()
 335             }
 336         }
 337     }
 338 }
 339
 340 /// A path like `Foo<'a, T>`
 341 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 342 pub struct AngleBracketedParameterData {
 343     /// The lifetime parameters for this path segment.
 344     pub lifetimes: Vec<Lifetime>,
 345     /// The type parameters for this path segment, if present.
 346     pub types: OwnedSlice<P<Ty>>,
 347     /// Bindings (equality constraints) on associated types, if present.
 348     /// E.g., `Foo<A=Bar>`.
 349     pub bindings: OwnedSlice<P<TypeBinding>>,
 350 }
 351
 352 impl AngleBracketedParameterData {
 353     fn is_empty(&self) -> bool {
 354         self.lifetimes.is_empty() && self.types.is_empty() && self.bindings.is_empty()
 355     }
 356 }
 357
 358 /// A path like `Foo(A,B) -> C`
 359 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 360 pub struct ParenthesizedParameterData {
 361     /// Overall span
 362     pub span: Span,
 363
 364     /// `(A,B)`
 365     pub inputs: Vec<P<Ty>>,
 366
 367     /// `C`
 368     pub output: Option<P<Ty>>,
 369 }
 370
 371 pub type CrateNum = u32;
 372
 373 pub type NodeId = u32;
 374
 375 #[derive(Clone, Eq, Ord, PartialOrd, PartialEq, RustcEncodable,
 376            RustcDecodable, Hash, Copy)]
 377 pub struct DefId {
 378     pub krate: CrateNum,
 379     pub node: NodeId,
 380 }
 381
 382 fn default_def_id_debug(_: DefId, _: &mut fmt::Formatter) -> fmt::Result { Ok(()) }
 383
 384 thread_local!(pub static DEF_ID_DEBUG: Cell<fn(DefId, &mut fmt::Formatter) -> fmt::Result> =
 385                 Cell::new(default_def_id_debug));
 386
 387 impl fmt::Debug for DefId {
 388     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 389         try!(write!(f, "DefId {{ krate: {}, node: {} }}",
 390                     self.krate, self.node));
 391         DEF_ID_DEBUG.with(|def_id_debug| def_id_debug.get()(*self, f))
 392     }
 393 }
 394
 395 impl DefId {
 396     /// Read the node id, asserting that this def-id is krate-local.
 397     pub fn local_id(&self) -> NodeId {
 398         assert_eq!(self.krate, LOCAL_CRATE);
 399         self.node
 400     }
 401 }
 402
 403 /// Item definitions in the currently-compiled crate would have the CrateNum
 404 /// LOCAL_CRATE in their DefId.
 405 pub const LOCAL_CRATE: CrateNum = 0;
 406 pub const CRATE_NODE_ID: NodeId = 0;
 407
 408 /// When parsing and doing expansions, we initially give all AST nodes this AST
 409 /// node value. Then later, in the renumber pass, we renumber them to have
 410 /// small, positive ids.
 411 pub const DUMMY_NODE_ID: NodeId = !0;
 412
 413 /// The AST represents all type param bounds as types.
 414 /// typeck::collect::compute_bounds matches these against
 415 /// the "special" built-in traits (see middle::lang_items) and
 416 /// detects Copy, Send and Sync.
 417 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 418 pub enum TyParamBound {
 419     TraitTyParamBound(PolyTraitRef, TraitBoundModifier),
 420     RegionTyParamBound(Lifetime)
 421 }
 422
 423 /// A modifier on a bound, currently this is only used for `?Sized`, where the
 424 /// modifier is `Maybe`. Negative bounds should also be handled here.
 425 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 426 pub enum TraitBoundModifier {
 427     None,
 428     Maybe,
 429 }
 430
 431 pub type TyParamBounds = OwnedSlice<TyParamBound>;
 432
 433 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 434 pub struct TyParam {
 435     pub ident: Ident,
 436     pub id: NodeId,
 437     pub bounds: TyParamBounds,
 438     pub default: Option<P<Ty>>,
 439     pub span: Span
 440 }
 441
 442 /// Represents lifetimes and type parameters attached to a declaration
 443 /// of a function, enum, trait, etc.
 444 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 445 pub struct Generics {
 446     pub lifetimes: Vec<LifetimeDef>,
 447     pub ty_params: OwnedSlice<TyParam>,
 448     pub where_clause: WhereClause,
 449 }
 450
 451 impl Generics {
 452     pub fn is_lt_parameterized(&self) -> bool {
 453         !self.lifetimes.is_empty()
 454     }
 455     pub fn is_type_parameterized(&self) -> bool {
 456         !self.ty_params.is_empty()
 457     }
 458     pub fn is_parameterized(&self) -> bool {
 459         self.is_lt_parameterized() || self.is_type_parameterized()
 460     }
 461 }
 462
 463 /// A `where` clause in a definition
 464 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 465 pub struct WhereClause {
 466     pub id: NodeId,
 467     pub predicates: Vec<WherePredicate>,
 468 }
 469
 470 /// A single predicate in a `where` clause
 471 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 472 pub enum WherePredicate {
 473     /// A type binding, eg `for<'c> Foo: Send+Clone+'c`
 474     BoundPredicate(WhereBoundPredicate),
 475     /// A lifetime predicate, e.g. `'a: 'b+'c`
 476     RegionPredicate(WhereRegionPredicate),
 477     /// An equality predicate (unsupported)
 478     EqPredicate(WhereEqPredicate)
 479 }
 480
 481 /// A type bound, eg `for<'c> Foo: Send+Clone+'c`
 482 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 483 pub struct WhereBoundPredicate {
 484     pub span: Span,
 485     /// Any lifetimes from a `for` binding
 486     pub bound_lifetimes: Vec<LifetimeDef>,
 487     /// The type being bounded
 488     pub bounded_ty: P<Ty>,
 489     /// Trait and lifetime bounds (`Clone+Send+'static`)
 490     pub bounds: OwnedSlice<TyParamBound>,
 491 }
 492
 493 /// A lifetime predicate, e.g. `'a: 'b+'c`
 494 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 495 pub struct WhereRegionPredicate {
 496     pub span: Span,
 497     pub lifetime: Lifetime,
 498     pub bounds: Vec<Lifetime>,
 499 }
 500
 501 /// An equality predicate (unsupported), e.g. `T=int`
 502 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 503 pub struct WhereEqPredicate {
 504     pub id: NodeId,
 505     pub span: Span,
 506     pub path: Path,
 507     pub ty: P<Ty>,
 508 }
 509
 510 /// The set of MetaItems that define the compilation environment of the crate,
 511 /// used to drive conditional compilation
 512 pub type CrateConfig = Vec<P<MetaItem>> ;
 513
 514 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 515 pub struct Crate {
 516     pub module: Mod,
 517     pub attrs: Vec<Attribute>,
 518     pub config: CrateConfig,
 519     pub span: Span,
 520     pub exported_macros: Vec<MacroDef>,
 521 }
 522
 523 pub type MetaItem = Spanned<MetaItem_>;
 524
 525 #[derive(Clone, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 526 pub enum MetaItem_ {
 527     MetaWord(InternedString),
 528     MetaList(InternedString, Vec<P<MetaItem>>),
 529     MetaNameValue(InternedString, Lit),
 530 }
 531
 532 // can't be derived because the MetaList requires an unordered comparison
 533 impl PartialEq for MetaItem_ {
 534     fn eq(&self, other: &MetaItem_) -> bool {
 535         match *self {
 536             MetaWord(ref ns) => match *other {
 537                 MetaWord(ref no) => (*ns) == (*no),
 538                 _ => false
 539             },
 540             MetaNameValue(ref ns, ref vs) => match *other {
 541                 MetaNameValue(ref no, ref vo) => {
 542                     (*ns) == (*no) && vs.node == vo.node
 543                 }
 544                 _ => false
 545             },
 546             MetaList(ref ns, ref miss) => match *other {
 547                 MetaList(ref no, ref miso) => {
 548                     ns == no &&
 549                         miss.iter().all(|mi| miso.iter().any(|x| x.node == mi.node))
 550                 }
 551                 _ => false
 552             }
 553         }
 554     }
 555 }
 556
 557 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 558 pub struct Block {
 559     /// Statements in a block
 560     pub stmts: Vec<P<Stmt>>,
 561     /// An expression at the end of the block
 562     /// without a semicolon, if any
 563     pub expr: Option<P<Expr>>,
 564     pub id: NodeId,
 565     /// Distinguishes between `unsafe { ... }` and `{ ... }`
 566     pub rules: BlockCheckMode,
 567     pub span: Span,
 568 }
 569
 570 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
 571 pub struct Pat {
 572     pub id: NodeId,
 573     pub node: Pat_,
 574     pub span: Span,
 575 }
 576
 577 impl fmt::Debug for Pat {
 578     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 579         write!(f, "pat({}: {})", self.id, pprust::pat_to_string(self))
 580     }
 581 }
 582
 583 /// A single field in a struct pattern
 584 ///
 585 /// Patterns like the fields of Foo `{ x, ref y, ref mut z }`
 586 /// are treated the same as` x: x, y: ref y, z: ref mut z`,
 587 /// except is_shorthand is true
 588 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 589 pub struct FieldPat {
 590     /// The identifier for the field
 591     pub ident: Ident,
 592     /// The pattern the field is destructured to
 593     pub pat: P<Pat>,
 594     pub is_shorthand: bool,
 595 }
 596
 597 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 598 pub enum BindingMode {
 599     BindByRef(Mutability),
 600     BindByValue(Mutability),
 601 }
 602
 603 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 604 pub enum PatWildKind {
 605     /// Represents the wildcard pattern `_`
 606     PatWildSingle,
 607
 608     /// Represents the wildcard pattern `..`
 609     PatWildMulti,
 610 }
 611
 612 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 613 pub enum Pat_ {
 614     /// Represents a wildcard pattern (either `_` or `..`)
 615     PatWild(PatWildKind),
 616
 617     /// A PatIdent may either be a new bound variable,
 618     /// or a nullary enum (in which case the third field
 619     /// is None).
 620     ///
 621     /// In the nullary enum case, the parser can't determine
 622     /// which it is. The resolver determines this, and
 623     /// records this pattern's NodeId in an auxiliary
 624     /// set (of "PatIdents that refer to nullary enums")
 625     PatIdent(BindingMode, SpannedIdent, Option<P<Pat>>),
 626
 627     /// "None" means a * pattern where we don't bind the fields to names.
 628     PatEnum(Path, Option<Vec<P<Pat>>>),
 629
 630     /// An associated const named using the qualified path `<T>::CONST` or
 631     /// `<T as Trait>::CONST`. Associated consts from inherent impls can be
 632     /// referred to as simply `T::CONST`, in which case they will end up as
 633     /// PatEnum, and the resolver will have to sort that out.
 634     PatQPath(QSelf, Path),
 635
 636     /// Destructuring of a struct, e.g. `Foo {x, y, ..}`
 637     /// The `bool` is `true` in the presence of a `..`
 638     PatStruct(Path, Vec<Spanned<FieldPat>>, bool),
 639     /// A tuple pattern `(a, b)`
 640     PatTup(Vec<P<Pat>>),
 641     /// A `box` pattern
 642     PatBox(P<Pat>),
 643     /// A reference pattern, e.g. `&mut (a, b)`
 644     PatRegion(P<Pat>, Mutability),
 645     /// A literal
 646     PatLit(P<Expr>),
 647     /// A range pattern, e.g. `1...2`
 648     PatRange(P<Expr>, P<Expr>),
 649     /// [a, b, ..i, y, z] is represented as:
 650     ///     PatVec(box [a, b], Some(i), box [y, z])
 651     PatVec(Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>),
 652     /// A macro pattern; pre-expansion
 653     PatMac(Mac),
 654 }
 655
 656 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 657 pub enum Mutability {
 658     MutMutable,
 659     MutImmutable,
 660 }
 661
 662 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 663 pub enum BinOp_ {
 664     /// The `+` operator (addition)
 665     BiAdd,
 666     /// The `-` operator (subtraction)
 667     BiSub,
 668     /// The `*` operator (multiplication)
 669     BiMul,
 670     /// The `/` operator (division)
 671     BiDiv,
 672     /// The `%` operator (modulus)
 673     BiRem,
 674     /// The `&&` operator (logical and)
 675     BiAnd,
 676     /// The `||` operator (logical or)
 677     BiOr,
 678     /// The `^` operator (bitwise xor)
 679     BiBitXor,
 680     /// The `&` operator (bitwise and)
 681     BiBitAnd,
 682     /// The `|` operator (bitwise or)
 683     BiBitOr,
 684     /// The `<<` operator (shift left)
 685     BiShl,
 686     /// The `>>` operator (shift right)
 687     BiShr,
 688     /// The `==` operator (equality)
 689     BiEq,
 690     /// The `<` operator (less than)
 691     BiLt,
 692     /// The `<=` operator (less than or equal to)
 693     BiLe,
 694     /// The `!=` operator (not equal to)
 695     BiNe,
 696     /// The `>=` operator (greater than or equal to)
 697     BiGe,
 698     /// The `>` operator (greater than)
 699     BiGt,
 700 }
 701
 702 pub type BinOp = Spanned<BinOp_>;
 703
 704 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 705 pub enum UnOp {
 706     /// The `box` operator
 707     UnUniq,
 708     /// The `*` operator for dereferencing
 709     UnDeref,
 710     /// The `!` operator for logical inversion
 711     UnNot,
 712     /// The `-` operator for negation
 713     UnNeg
 714 }
 715
 716 /// A statement
 717 pub type Stmt = Spanned<Stmt_>;
 718
 719 impl fmt::Debug for Stmt {
 720     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 721         write!(f, "stmt({}: {})",
 722                ast_util::stmt_id(self),
 723                pprust::stmt_to_string(self))
 724     }
 725 }
 726
 727
 728 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
 729 pub enum Stmt_ {
 730     /// Could be an item or a local (let) binding:
 731     StmtDecl(P<Decl>, NodeId),
 732
 733     /// Expr without trailing semi-colon (must have unit type):
 734     StmtExpr(P<Expr>, NodeId),
 735
 736     /// Expr with trailing semi-colon (may have any type):
 737     StmtSemi(P<Expr>, NodeId),
 738
 739     StmtMac(P<Mac>, MacStmtStyle),
 740 }
 741 #[derive(Clone, Copy, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 742 pub enum MacStmtStyle {
 743     /// The macro statement had a trailing semicolon, e.g. `foo! { ... };`
 744     /// `foo!(...);`, `foo![...];`
 745     MacStmtWithSemicolon,
 746     /// The macro statement had braces; e.g. foo! { ... }
 747     MacStmtWithBraces,
 748     /// The macro statement had parentheses or brackets and no semicolon; e.g.
 749     /// `foo!(...)`. All of these will end up being converted into macro
 750     /// expressions.
 751     MacStmtWithoutBraces,
 752 }
 753
 754 // FIXME (pending discussion of #1697, #2178...): local should really be
 755 // a refinement on pat.
 756 /// Local represents a `let` statement, e.g., `let <pat>:<ty> = <expr>;`
 757 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 758 pub struct Local {
 759     pub pat: P<Pat>,
 760     pub ty: Option<P<Ty>>,
 761     /// Initializer expression to set the value, if any
 762     pub init: Option<P<Expr>>,
 763     pub id: NodeId,
 764     pub span: Span,
 765 }
 766
 767 pub type Decl = Spanned<Decl_>;
 768
 769 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 770 pub enum Decl_ {
 771     /// A local (let) binding:
 772     DeclLocal(P<Local>),
 773     /// An item binding:
 774     DeclItem(P<Item>),
 775 }
 776
 777 /// represents one arm of a 'match'
 778 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 779 pub struct Arm {
 780     pub attrs: Vec<Attribute>,
 781     pub pats: Vec<P<Pat>>,
 782     pub guard: Option<P<Expr>>,
 783     pub body: P<Expr>,
 784 }
 785
 786 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 787 pub struct Field {
 788     pub ident: SpannedIdent,
 789     pub expr: P<Expr>,
 790     pub span: Span,
 791 }
 792
 793 pub type SpannedIdent = Spanned<Ident>;
 794
 795 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 796 pub enum BlockCheckMode {
 797     DefaultBlock,
 798     UnsafeBlock(UnsafeSource),
 799     PushUnsafeBlock(UnsafeSource),
 800     PopUnsafeBlock(UnsafeSource),
 801 }
 802
 803 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 804 pub enum UnsafeSource {
 805     CompilerGenerated,
 806     UserProvided,
 807 }
 808
 809 /// An expression
 810 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash,)]
 811 pub struct Expr {
 812     pub id: NodeId,
 813     pub node: Expr_,
 814     pub span: Span,
 815 }
 816
 817 impl fmt::Debug for Expr {
 818     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 819         write!(f, "expr({}: {})", self.id, pprust::expr_to_string(self))
 820     }
 821 }
 822
 823 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 824 pub enum Expr_ {
 825     /// First expr is the place; second expr is the value.
 826     ExprBox(Option<P<Expr>>, P<Expr>),
 827     /// An array (`[a, b, c, d]`)
 828     ExprVec(Vec<P<Expr>>),
 829     /// A function call
 830     ///
 831     /// The first field resolves to the function itself,
 832     /// and the second field is the list of arguments
 833     ExprCall(P<Expr>, Vec<P<Expr>>),
 834     /// A method call (`x.foo::<Bar, Baz>(a, b, c, d)`)
 835     ///
 836     /// The `SpannedIdent` is the identifier for the method name.
 837     /// The vector of `Ty`s are the ascripted type parameters for the method
 838     /// (within the angle brackets).
 839     ///
 840     /// The first element of the vector of `Expr`s is the expression that evaluates
 841     /// to the object on which the method is being called on (the receiver),
 842     /// and the remaining elements are the rest of the arguments.
 843     ///
 844     /// Thus, `x.foo::<Bar, Baz>(a, b, c, d)` is represented as
 845     /// `ExprMethodCall(foo, [Bar, Baz], [x, a, b, c, d])`.
 846     ExprMethodCall(SpannedIdent, Vec<P<Ty>>, Vec<P<Expr>>),
 847     /// A tuple (`(a, b, c ,d)`)
 848     ExprTup(Vec<P<Expr>>),
 849     /// A binary operation (For example: `a + b`, `a * b`)
 850     ExprBinary(BinOp, P<Expr>, P<Expr>),
 851     /// A unary operation (For example: `!x`, `*x`)
 852     ExprUnary(UnOp, P<Expr>),
 853     /// A literal (For example: `1u8`, `"foo"`)
 854     ExprLit(P<Lit>),
 855     /// A cast (`foo as f64`)
 856     ExprCast(P<Expr>, P<Ty>),
 857     /// An `if` block, with an optional else block
 858     ///
 859     /// `if expr { block } else { expr }`
 860     ExprIf(P<Expr>, P<Block>, Option<P<Expr>>),
 861     /// An `if let` expression with an optional else block
 862     ///
 863     /// `if let pat = expr { block } else { expr }`
 864     ///
 865     /// This is desugared to a `match` expression.
 866     ExprIfLet(P<Pat>, P<Expr>, P<Block>, Option<P<Expr>>),
 867     // FIXME #6993: change to Option<Name> ... or not, if these are hygienic.
 868     /// A while loop, with an optional label
 869     ///
 870     /// `'label: while expr { block }`
 871     ExprWhile(P<Expr>, P<Block>, Option<Ident>),
 872     // FIXME #6993: change to Option<Name> ... or not, if these are hygienic.
 873     /// A while-let loop, with an optional label
 874     ///
 875     /// `'label: while let pat = expr { block }`
 876     ///
 877     /// This is desugared to a combination of `loop` and `match` expressions.
 878     ExprWhileLet(P<Pat>, P<Expr>, P<Block>, Option<Ident>),
 879     // FIXME #6993: change to Option<Name> ... or not, if these are hygienic.
 880     /// A for loop, with an optional label
 881     ///
 882     /// `'label: for pat in expr { block }`
 883     ///
 884     /// This is desugared to a combination of `loop` and `match` expressions.
 885     ExprForLoop(P<Pat>, P<Expr>, P<Block>, Option<Ident>),
 886     /// Conditionless loop (can be exited with break, continue, or return)
 887     ///
 888     /// `'label: loop { block }`
 889     // FIXME #6993: change to Option<Name> ... or not, if these are hygienic.
 890     ExprLoop(P<Block>, Option<Ident>),
 891     /// A `match` block, with a source that indicates whether or not it is
 892     /// the result of a desugaring, and if so, which kind.
 893     ExprMatch(P<Expr>, Vec<Arm>, MatchSource),
 894     /// A closure (for example, `move |a, b, c| {a + b + c}`)
 895     ExprClosure(CaptureClause, P<FnDecl>, P<Block>),
 896     /// A block (`{ ... }`)
 897     ExprBlock(P<Block>),
 898
 899     /// An assignment (`a = foo()`)
 900     ExprAssign(P<Expr>, P<Expr>),
 901     /// An assignment with an operator
 902     ///
 903     /// For example, `a += 1`.
 904     ExprAssignOp(BinOp, P<Expr>, P<Expr>),
 905     /// Access of a named struct field (`obj.foo`)
 906     ExprField(P<Expr>, SpannedIdent),
 907     /// Access of an unnamed field of a struct or tuple-struct
 908     ///
 909     /// For example, `foo.0`.
 910     ExprTupField(P<Expr>, Spanned<usize>),
 911     /// An indexing operation (`foo[2]`)
 912     ExprIndex(P<Expr>, P<Expr>),
 913     /// A range (`1..2`, `1..`, or `..2`)
 914     ExprRange(Option<P<Expr>>, Option<P<Expr>>),
 915
 916     /// Variable reference, possibly containing `::` and/or type
 917     /// parameters, e.g. foo::bar::<baz>.
 918     ///
 919     /// Optionally "qualified",
 920     /// e.g. `<Vec<T> as SomeTrait>::SomeType`.
 921     ExprPath(Option<QSelf>, Path),
 922
 923     /// A referencing operation (`&a` or `&mut a`)
 924     ExprAddrOf(Mutability, P<Expr>),
 925     /// A `break`, with an optional label to break
 926     ExprBreak(Option<Ident>),
 927     /// A `continue`, with an optional label
 928     ExprAgain(Option<Ident>),
 929     /// A `return`, with an optional value to be returned
 930     ExprRet(Option<P<Expr>>),
 931
 932     /// Output of the `asm!()` macro
 933     ExprInlineAsm(InlineAsm),
 934
 935     /// A macro invocation; pre-expansion
 936     ExprMac(Mac),
 937
 938     /// A struct literal expression.
 939     ///
 940     /// For example, `Foo {x: 1, y: 2}`, or
 941     /// `Foo {x: 1, .. base}`, where `base` is the `Option<Expr>`.
 942     ExprStruct(Path, Vec<Field>, Option<P<Expr>>),
 943
 944     /// A vector literal constructed from one repeated element.
 945     ///
 946     /// For example, `[1u8; 5]`. The first expression is the element
 947     /// to be repeated; the second is the number of times to repeat it.
 948     ExprRepeat(P<Expr>, P<Expr>),
 949
 950     /// No-op: used solely so we can pretty-print faithfully
 951     ExprParen(P<Expr>)
 952 }
 953
 954 /// The explicit Self type in a "qualified path". The actual
 955 /// path, including the trait and the associated item, is stored
 956 /// separately. `position` represents the index of the associated
 957 /// item qualified with this Self type.
 958 ///
 959 ///     <Vec<T> as a::b::Trait>::AssociatedItem
 960 ///      ^~~~~     ~~~~~~~~~~~~~~^
 961 ///      ty        position = 3
 962 ///
 963 ///     <Vec<T>>::AssociatedItem
 964 ///      ^~~~~    ^
 965 ///      ty       position = 0
 966 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 967 pub struct QSelf {
 968     pub ty: P<Ty>,
 969     pub position: usize
 970 }
 971
 972 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 973 pub enum MatchSource {
 974     Normal,
 975     IfLetDesugar { contains_else_clause: bool },
 976     WhileLetDesugar,
 977     ForLoopDesugar,
 978 }
 979
 980 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 981 pub enum CaptureClause {
 982     CaptureByValue,
 983     CaptureByRef,
 984 }
 985
 986 /// A delimited sequence of token trees
 987 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 988 pub struct Delimited {
 989     /// The type of delimiter
 990     pub delim: token::DelimToken,
 991     /// The span covering the opening delimiter
 992     pub open_span: Span,
 993     /// The delimited sequence of token trees
 994     pub tts: Vec<TokenTree>,
 995     /// The span covering the closing delimiter
 996     pub close_span: Span,
 997 }
 998
 999 impl Delimited {
1000     /// Returns the opening delimiter as a token.
1001     pub fn open_token(&self) -> token::Token {
1002         token::OpenDelim(self.delim)
1003     }
1004
1005     /// Returns the closing delimiter as a token.
1006     pub fn close_token(&self) -> token::Token {
1007         token::CloseDelim(self.delim)
1008     }
1009
1010     /// Returns the opening delimiter as a token tree.
1011     pub fn open_tt(&self) -> TokenTree {
1012         TtToken(self.open_span, self.open_token())
1013     }
1014
1015     /// Returns the closing delimiter as a token tree.
1016     pub fn close_tt(&self) -> TokenTree {
1017         TtToken(self.close_span, self.close_token())
1018     }
1019 }
1020
1021 /// A sequence of token treesee
1022 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1023 pub struct SequenceRepetition {
1024     /// The sequence of token trees
1025     pub tts: Vec<TokenTree>,
1026     /// The optional separator
1027     pub separator: Option<token::Token>,
1028     /// Whether the sequence can be repeated zero (*), or one or more times (+)
1029     pub op: KleeneOp,
1030     /// The number of `MatchNt`s that appear in the sequence (and subsequences)
1031     pub num_captures: usize,
1032 }
1033
1034 /// A Kleene-style [repetition operator](http://en.wikipedia.org/wiki/Kleene_star)
1035 /// for token sequences.
1036 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1037 pub enum KleeneOp {
1038     ZeroOrMore,
1039     OneOrMore,
1040 }
1041
1042 /// When the main rust parser encounters a syntax-extension invocation, it
1043 /// parses the arguments to the invocation as a token-tree. This is a very
1044 /// loose structure, such that all sorts of different AST-fragments can
1045 /// be passed to syntax extensions using a uniform type.
1046 ///
1047 /// If the syntax extension is an MBE macro, it will attempt to match its
1048 /// LHS token tree against the provided token tree, and if it finds a
1049 /// match, will transcribe the RHS token tree, splicing in any captured
1050 /// macro_parser::matched_nonterminals into the `SubstNt`s it finds.
1051 ///
1052 /// The RHS of an MBE macro is the only place `SubstNt`s are substituted.
1053 /// Nothing special happens to misnamed or misplaced `SubstNt`s.
1054 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1055 pub enum TokenTree {
1056     /// A single token
1057     TtToken(Span, token::Token),
1058     /// A delimited sequence of token trees
1059     TtDelimited(Span, Rc<Delimited>),
1060
1061     // This only makes sense in MBE macros.
1062
1063     /// A kleene-style repetition sequence with a span
1064     // FIXME(eddyb) #12938 Use DST.
1065     TtSequence(Span, Rc<SequenceRepetition>),
1066 }
1067
1068 impl TokenTree {
1069     pub fn len(&self) -> usize {
1070         match *self {
1071             TtToken(_, token::DocComment(name)) => {
1072                 match doc_comment_style(&name.as_str()) {
1073                     AttrOuter => 2,
1074                     AttrInner => 3
1075                 }
1076             }
1077             TtToken(_, token::SpecialVarNt(..)) => 2,
1078             TtToken(_, token::MatchNt(..)) => 3,
1079             TtDelimited(_, ref delimed) => {
1080                 delimed.tts.len() + 2
1081             }
1082             TtSequence(_, ref seq) => {
1083                 seq.tts.len()
1084             }
1085             TtToken(..) => 0
1086         }
1087     }
1088
1089     pub fn get_tt(&self, index: usize) -> TokenTree {
1090         match (self, index) {
1091             (&TtToken(sp, token::DocComment(_)), 0) => {
1092                 TtToken(sp, token::Pound)
1093             }
1094             (&TtToken(sp, token::DocComment(name)), 1)
1095             if doc_comment_style(&name.as_str()) == AttrInner => {
1096                 TtToken(sp, token::Not)
1097             }
1098             (&TtToken(sp, token::DocComment(name)), _) => {
1099                 let stripped = strip_doc_comment_decoration(&name.as_str());
1100                 TtDelimited(sp, Rc::new(Delimited {
1101                     delim: token::Bracket,
1102                     open_span: sp,
1103                     tts: vec![TtToken(sp, token::Ident(token::str_to_ident("doc"),
1104                                                        token::Plain)),
1105                               TtToken(sp, token::Eq),
1106                               TtToken(sp, token::Literal(
1107                                   token::StrRaw(token::intern(&stripped), 0), None))],
1108                     close_span: sp,
1109                 }))
1110             }
1111             (&TtDelimited(_, ref delimed), _) => {
1112                 if index == 0 {
1113                     return delimed.open_tt();
1114                 }
1115                 if index == delimed.tts.len() + 1 {
1116                     return delimed.close_tt();
1117                 }
1118                 delimed.tts[index - 1].clone()
1119             }
1120             (&TtToken(sp, token::SpecialVarNt(var)), _) => {
1121                 let v = [TtToken(sp, token::Dollar),
1122                          TtToken(sp, token::Ident(token::str_to_ident(var.as_str()),
1123                                                   token::Plain))];
1124                 v[index].clone()
1125             }
1126             (&TtToken(sp, token::MatchNt(name, kind, name_st, kind_st)), _) => {
1127                 let v = [TtToken(sp, token::SubstNt(name, name_st)),
1128                          TtToken(sp, token::Colon),
1129                          TtToken(sp, token::Ident(kind, kind_st))];
1130                 v[index].clone()
1131             }
1132             (&TtSequence(_, ref seq), _) => {
1133                 seq.tts[index].clone()
1134             }
1135             _ => panic!("Cannot expand a token tree")
1136         }
1137     }
1138
1139     /// Returns the `Span` corresponding to this token tree.
1140     pub fn get_span(&self) -> Span {
1141         match *self {
1142             TtToken(span, _)     => span,
1143             TtDelimited(span, _) => span,
1144             TtSequence(span, _)  => span,
1145         }
1146     }
1147
1148     /// Use this token tree as a matcher to parse given tts.
1149     pub fn parse(cx: &base::ExtCtxt, mtch: &[TokenTree], tts: &[TokenTree])
1150                  -> macro_parser::NamedParseResult {
1151         // `None` is because we're not interpolating
1152         let arg_rdr = lexer::new_tt_reader_with_doc_flag(&cx.parse_sess().span_diagnostic,
1153                                                          None,
1154                                                          None,
1155                                                          tts.iter().cloned().collect(),
1156                                                          true);
1157         macro_parser::parse(cx.parse_sess(), cx.cfg(), arg_rdr, mtch)
1158     }
1159 }
1160
1161 pub type Mac = Spanned<Mac_>;
1162
1163 /// Represents a macro invocation. The Path indicates which macro
1164 /// is being invoked, and the vector of token-trees contains the source
1165 /// of the macro invocation.
1166 ///
1167 /// There's only one flavor, now, so this could presumably be simplified.
1168 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1169 pub enum Mac_ {
1170     // NB: the additional ident for a macro_rules-style macro is actually
1171     // stored in the enclosing item. Oog.
1172     MacInvocTT(Path, Vec<TokenTree>, SyntaxContext),   // new macro-invocation
1173 }
1174
1175 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1176 pub enum StrStyle {
1177     /// A regular string, like `"foo"`
1178     CookedStr,
1179     /// A raw string, like `r##"foo"##`
1180     ///
1181     /// The uint is the number of `#` symbols used
1182     RawStr(usize)
1183 }
1184
1185 /// A literal
1186 pub type Lit = Spanned<Lit_>;
1187
1188 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1189 pub enum Sign {
1190     Minus,
1191     Plus
1192 }
1193
1194 impl Sign {
1195     pub fn new<T: IntSign>(n: T) -> Sign {
1196         n.sign()
1197     }
1198 }
1199
1200 pub trait IntSign {
1201     fn sign(&self) -> Sign;
1202 }
1203 macro_rules! doit {
1204     ($($t:ident)*) => ($(impl IntSign for $t {
1205         #[allow(unused_comparisons)]
1206         fn sign(&self) -> Sign {
1207             if *self < 0 {Minus} else {Plus}
1208         }
1209     })*)
1210 }
1211 doit! { i8 i16 i32 i64 isize u8 u16 u32 u64 usize }
1212
1213 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1214 pub enum LitIntType {
1215     SignedIntLit(IntTy, Sign),
1216     UnsignedIntLit(UintTy),
1217     UnsuffixedIntLit(Sign)
1218 }
1219
1220 impl LitIntType {
1221     pub fn suffix_len(&self) -> usize {
1222         match *self {
1223             UnsuffixedIntLit(_) => 0,
1224             SignedIntLit(s, _) => s.suffix_len(),
1225             UnsignedIntLit(u) => u.suffix_len()
1226         }
1227     }
1228 }
1229
1230 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1231 pub enum Lit_ {
1232     /// A string literal (`"foo"`)
1233     LitStr(InternedString, StrStyle),
1234     /// A byte string (`b"foo"`)
1235     LitBinary(Rc<Vec<u8>>),
1236     /// A byte char (`b'f'`)
1237     LitByte(u8),
1238     /// A character literal (`'a'`)
1239     LitChar(char),
1240     /// An integer literal (`1u8`)
1241     LitInt(u64, LitIntType),
1242     /// A float literal (`1f64` or `1E10f64`)
1243     LitFloat(InternedString, FloatTy),
1244     /// A float literal without a suffix (`1.0 or 1.0E10`)
1245     LitFloatUnsuffixed(InternedString),
1246     /// A boolean literal
1247     LitBool(bool),
1248 }
1249
1250 // NB: If you change this, you'll probably want to change the corresponding
1251 // type structure in middle/ty.rs as well.
1252 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1253 pub struct MutTy {
1254     pub ty: P<Ty>,
1255     pub mutbl: Mutability,
1256 }
1257
1258 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1259 pub struct TypeField {
1260     pub ident: Ident,
1261     pub mt: MutTy,
1262     pub span: Span,
1263 }
1264
1265 /// Represents a method's signature in a trait declaration,
1266 /// or in an implementation.
1267 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1268 pub struct MethodSig {
1269     pub unsafety: Unsafety,
1270     pub constness: Constness,
1271     pub abi: Abi,
1272     pub decl: P<FnDecl>,
1273     pub generics: Generics,
1274     pub explicit_self: ExplicitSelf,
1275 }
1276
1277 /// Represents a method declaration in a trait declaration, possibly including
1278 /// a default implementation A trait method is either required (meaning it
1279 /// doesn't have an implementation, just a signature) or provided (meaning it
1280 /// has a default implementation).
1281 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1282 pub struct TraitItem {
1283     pub id: NodeId,
1284     pub ident: Ident,
1285     pub attrs: Vec<Attribute>,
1286     pub node: TraitItem_,
1287     pub span: Span,
1288 }
1289
1290 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1291 pub enum TraitItem_ {
1292     ConstTraitItem(P<Ty>, Option<P<Expr>>),
1293     MethodTraitItem(MethodSig, Option<P<Block>>),
1294     TypeTraitItem(TyParamBounds, Option<P<Ty>>),
1295 }
1296
1297 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1298 pub struct ImplItem {
1299     pub id: NodeId,
1300     pub ident: Ident,
1301     pub vis: Visibility,
1302     pub attrs: Vec<Attribute>,
1303     pub node: ImplItem_,
1304     pub span: Span,
1305 }
1306
1307 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1308 pub enum ImplItem_ {
1309     ConstImplItem(P<Ty>, P<Expr>),
1310     MethodImplItem(MethodSig, P<Block>),
1311     TypeImplItem(P<Ty>),
1312     MacImplItem(Mac),
1313 }
1314
1315 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
1316 pub enum IntTy {
1317     TyIs,
1318     TyI8,
1319     TyI16,
1320     TyI32,
1321     TyI64,
1322 }
1323
1324 impl fmt::Debug for IntTy {
1325     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1326         fmt::Display::fmt(self, f)
1327     }
1328 }
1329
1330 impl fmt::Display for IntTy {
1331     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1332         write!(f, "{}", ast_util::int_ty_to_string(*self, None))
1333     }
1334 }
1335
1336 impl IntTy {
1337     pub fn suffix_len(&self) -> usize {
1338         match *self {
1339             TyIs | TyI8 => 2,
1340             TyI16 | TyI32 | TyI64  => 3,
1341         }
1342     }
1343 }
1344
1345 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
1346 pub enum UintTy {
1347     TyUs,
1348     TyU8,
1349     TyU16,
1350     TyU32,
1351     TyU64,
1352 }
1353
1354 impl UintTy {
1355     pub fn suffix_len(&self) -> usize {
1356         match *self {
1357             TyUs | TyU8 => 2,
1358             TyU16 | TyU32 | TyU64  => 3,
1359         }
1360     }
1361 }
1362
1363 impl fmt::Debug for UintTy {
1364     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1365         fmt::Display::fmt(self, f)
1366     }
1367 }
1368
1369 impl fmt::Display for UintTy {
1370     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1371         write!(f, "{}", ast_util::uint_ty_to_string(*self, None))
1372     }
1373 }
1374
1375 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
1376 pub enum FloatTy {
1377     TyF32,
1378     TyF64,
1379 }
1380
1381 impl fmt::Debug for FloatTy {
1382     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1383         fmt::Display::fmt(self, f)
1384     }
1385 }
1386
1387 impl fmt::Display for FloatTy {
1388     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1389         write!(f, "{}", ast_util::float_ty_to_string(*self))
1390     }
1391 }
1392
1393 impl FloatTy {
1394     pub fn suffix_len(&self) -> usize {
1395         match *self {
1396             TyF32 | TyF64 => 3, // add F128 handling here
1397         }
1398     }
1399 }
1400
1401 // Bind a type to an associated type: `A=Foo`.
1402 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1403 pub struct TypeBinding {
1404     pub id: NodeId,
1405     pub ident: Ident,
1406     pub ty: P<Ty>,
1407     pub span: Span,
1408 }
1409
1410
1411 // NB PartialEq method appears below.
1412 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
1413 pub struct Ty {
1414     pub id: NodeId,
1415     pub node: Ty_,
1416     pub span: Span,
1417 }
1418
1419 impl fmt::Debug for Ty {
1420     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1421         write!(f, "type({})", pprust::ty_to_string(self))
1422     }
1423 }
1424
1425 /// Not represented directly in the AST, referred to by name through a ty_path.
1426 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1427 pub enum PrimTy {
1428     TyInt(IntTy),
1429     TyUint(UintTy),
1430     TyFloat(FloatTy),
1431     TyStr,
1432     TyBool,
1433     TyChar
1434 }
1435
1436 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1437 pub struct BareFnTy {
1438     pub unsafety: Unsafety,
1439     pub abi: Abi,
1440     pub lifetimes: Vec<LifetimeDef>,
1441     pub decl: P<FnDecl>
1442 }
1443
1444 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1445 /// The different kinds of types recognized by the compiler
1446 pub enum Ty_ {
1447     TyVec(P<Ty>),
1448     /// A fixed length array (`[T; n]`)
1449     TyFixedLengthVec(P<Ty>, P<Expr>),
1450     /// A raw pointer (`*const T` or `*mut T`)
1451     TyPtr(MutTy),
1452     /// A reference (`&'a T` or `&'a mut T`)
1453     TyRptr(Option<Lifetime>, MutTy),
1454     /// A bare function (e.g. `fn(usize) -> bool`)
1455     TyBareFn(P<BareFnTy>),
1456     /// A tuple (`(A, B, C, D,...)`)
1457     TyTup(Vec<P<Ty>> ),
1458     /// A path (`module::module::...::Type`), optionally
1459     /// "qualified", e.g. `<Vec<T> as SomeTrait>::SomeType`.
1460     ///
1461     /// Type parameters are stored in the Path itself
1462     TyPath(Option<QSelf>, Path),
1463     /// Something like `A+B`. Note that `B` must always be a path.
1464     TyObjectSum(P<Ty>, TyParamBounds),
1465     /// A type like `for<'a> Foo<&'a Bar>`
1466     TyPolyTraitRef(TyParamBounds),
1467     /// No-op; kept solely so that we can pretty-print faithfully
1468     TyParen(P<Ty>),
1469     /// Unused for now
1470     TyTypeof(P<Expr>),
1471     /// TyInfer means the type should be inferred instead of it having been
1472     /// specified. This can appear anywhere in a type.
1473     TyInfer,
1474 }
1475
1476 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1477 pub enum AsmDialect {
1478     AsmAtt,
1479     AsmIntel
1480 }
1481
1482 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1483 pub struct InlineAsm {
1484     pub asm: InternedString,
1485     pub asm_str_style: StrStyle,
1486     pub outputs: Vec<(InternedString, P<Expr>, bool)>,
1487     pub inputs: Vec<(InternedString, P<Expr>)>,
1488     pub clobbers: Vec<InternedString>,
1489     pub volatile: bool,
1490     pub alignstack: bool,
1491     pub dialect: AsmDialect,
1492     pub expn_id: ExpnId,
1493 }
1494
1495 /// represents an argument in a function header
1496 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1497 pub struct Arg {
1498     pub ty: P<Ty>,
1499     pub pat: P<Pat>,
1500     pub id: NodeId,
1501 }
1502
1503 impl Arg {
1504     pub fn new_self(span: Span, mutability: Mutability, self_ident: Ident) -> Arg {
1505         let path = Spanned{span:span,node:self_ident};
1506         Arg {
1507             // HACK(eddyb) fake type for the self argument.
1508             ty: P(Ty {
1509                 id: DUMMY_NODE_ID,
1510                 node: TyInfer,
1511                 span: DUMMY_SP,
1512             }),
1513             pat: P(Pat {
1514                 id: DUMMY_NODE_ID,
1515                 node: PatIdent(BindByValue(mutability), path, None),
1516                 span: span
1517             }),
1518             id: DUMMY_NODE_ID
1519         }
1520     }
1521 }
1522
1523 /// Represents the header (not the body) of a function declaration
1524 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1525 pub struct FnDecl {
1526     pub inputs: Vec<Arg>,
1527     pub output: FunctionRetTy,
1528     pub variadic: bool
1529 }
1530
1531 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1532 pub enum Unsafety {
1533     Unsafe,
1534     Normal,
1535 }
1536
1537 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1538 pub enum Constness {
1539     Const,
1540     NotConst,
1541 }
1542
1543 impl fmt::Display for Unsafety {
1544     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1545         fmt::Display::fmt(match *self {
1546             Unsafety::Normal => "normal",
1547             Unsafety::Unsafe => "unsafe",
1548         }, f)
1549     }
1550 }
1551
1552 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
1553 pub enum ImplPolarity {
1554     /// `impl Trait for Type`
1555     Positive,
1556     /// `impl !Trait for Type`
1557     Negative,
1558 }
1559
1560 impl fmt::Debug for ImplPolarity {
1561     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1562         match *self {
1563             ImplPolarity::Positive => "positive".fmt(f),
1564             ImplPolarity::Negative => "negative".fmt(f),
1565         }
1566     }
1567 }
1568
1569
1570 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1571 pub enum FunctionRetTy {
1572     /// Functions with return type `!`that always
1573     /// raise an error or exit (i.e. never return to the caller)
1574     NoReturn(Span),
1575     /// Return type is not specified.
1576     ///
1577     /// Functions default to `()` and
1578     /// closures default to inference. Span points to where return
1579     /// type would be inserted.
1580     DefaultReturn(Span),
1581     /// Everything else
1582     Return(P<Ty>),
1583 }
1584
1585 impl FunctionRetTy {
1586     pub fn span(&self) -> Span {
1587         match *self {
1588             NoReturn(span) => span,
1589             DefaultReturn(span) => span,
1590             Return(ref ty) => ty.span
1591         }
1592     }
1593 }
1594
1595 /// Represents the kind of 'self' associated with a method
1596 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1597 pub enum ExplicitSelf_ {
1598     /// No self
1599     SelfStatic,
1600     /// `self`
1601     SelfValue(Ident),
1602     /// `&'lt self`, `&'lt mut self`
1603     SelfRegion(Option<Lifetime>, Mutability, Ident),
1604     /// `self: TYPE`
1605     SelfExplicit(P<Ty>, Ident),
1606 }
1607
1608 pub type ExplicitSelf = Spanned<ExplicitSelf_>;
1609
1610 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1611 pub struct Mod {
1612     /// A span from the first token past `{` to the last token until `}`.
1613     /// For `mod foo;`, the inner span ranges from the first token
1614     /// to the last token in the external file.
1615     pub inner: Span,
1616     pub items: Vec<P<Item>>,
1617 }
1618
1619 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1620 pub struct ForeignMod {
1621     pub abi: Abi,
1622     pub items: Vec<P<ForeignItem>>,
1623 }
1624
1625 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1626 pub struct VariantArg {
1627     pub ty: P<Ty>,
1628     pub id: NodeId,
1629 }
1630
1631 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1632 pub enum VariantKind {
1633     /// Tuple variant, e.g. `Foo(A, B)`
1634     TupleVariantKind(Vec<VariantArg>),
1635     /// Struct variant, e.g. `Foo {x: A, y: B}`
1636     StructVariantKind(P<StructDef>),
1637 }
1638
1639 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1640 pub struct EnumDef {
1641     pub variants: Vec<P<Variant>>,
1642 }
1643
1644 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1645 pub struct Variant_ {
1646     pub name: Ident,
1647     pub attrs: Vec<Attribute>,
1648     pub kind: VariantKind,
1649     pub id: NodeId,
1650     /// Explicit discriminant, eg `Foo = 1`
1651     pub disr_expr: Option<P<Expr>>,
1652     pub vis: Visibility,
1653 }
1654
1655 pub type Variant = Spanned<Variant_>;
1656
1657 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1658 pub enum PathListItem_ {
1659     PathListIdent { name: Ident, id: NodeId },
1660     PathListMod { id: NodeId }
1661 }
1662
1663 impl PathListItem_ {
1664     pub fn id(&self) -> NodeId {
1665         match *self {
1666             PathListIdent { id, .. } | PathListMod { id } => id
1667         }
1668     }
1669 }
1670
1671 pub type PathListItem = Spanned<PathListItem_>;
1672
1673 pub type ViewPath = Spanned<ViewPath_>;
1674
1675 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1676 pub enum ViewPath_ {
1677
1678     /// `foo::bar::baz as quux`
1679     ///
1680     /// or just
1681     ///
1682     /// `foo::bar::baz` (with `as baz` implicitly on the right)
1683     ViewPathSimple(Ident, Path),
1684
1685     /// `foo::bar::*`
1686     ViewPathGlob(Path),
1687
1688     /// `foo::bar::{a,b,c}`
1689     ViewPathList(Path, Vec<PathListItem>)
1690 }
1691
1692 /// Meta-data associated with an item
1693 pub type Attribute = Spanned<Attribute_>;
1694
1695 /// Distinguishes between Attributes that decorate items and Attributes that
1696 /// are contained as statements within items. These two cases need to be
1697 /// distinguished for pretty-printing.
1698 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1699 pub enum AttrStyle {
1700     AttrOuter,
1701     AttrInner,
1702 }
1703
1704 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1705 pub struct AttrId(pub usize);
1706
1707 /// Doc-comments are promoted to attributes that have is_sugared_doc = true
1708 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1709 pub struct Attribute_ {
1710     pub id: AttrId,
1711     pub style: AttrStyle,
1712     pub value: P<MetaItem>,
1713     pub is_sugared_doc: bool,
1714 }
1715
1716 /// TraitRef's appear in impls.
1717 ///
1718 /// resolve maps each TraitRef's ref_id to its defining trait; that's all
1719 /// that the ref_id is for. The impl_id maps to the "self type" of this impl.
1720 /// If this impl is an ItemImpl, the impl_id is redundant (it could be the
1721 /// same as the impl's node id).
1722 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1723 pub struct TraitRef {
1724     pub path: Path,
1725     pub ref_id: NodeId,
1726 }
1727
1728 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1729 pub struct PolyTraitRef {
1730     /// The `'a` in `<'a> Foo<&'a T>`
1731     pub bound_lifetimes: Vec<LifetimeDef>,
1732
1733     /// The `Foo<&'a T>` in `<'a> Foo<&'a T>`
1734     pub trait_ref: TraitRef,
1735
1736     pub span: Span,
1737 }
1738
1739 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1740 pub enum Visibility {
1741     Public,
1742     Inherited,
1743 }
1744
1745 impl Visibility {
1746     pub fn inherit_from(&self, parent_visibility: Visibility) -> Visibility {
1747         match self {
1748             &Inherited => parent_visibility,
1749             &Public => *self
1750         }
1751     }
1752 }
1753
1754 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1755 pub struct StructField_ {
1756     pub kind: StructFieldKind,
1757     pub id: NodeId,
1758     pub ty: P<Ty>,
1759     pub attrs: Vec<Attribute>,
1760 }
1761
1762 impl StructField_ {
1763     pub fn ident(&self) -> Option<Ident> {
1764         match self.kind {
1765             NamedField(ref ident, _) => Some(ident.clone()),
1766             UnnamedField(_) => None
1767         }
1768     }
1769 }
1770
1771 pub type StructField = Spanned<StructField_>;
1772
1773 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1774 pub enum StructFieldKind {
1775     NamedField(Ident, Visibility),
1776     /// Element of a tuple-like struct
1777     UnnamedField(Visibility),
1778 }
1779
1780 impl StructFieldKind {
1781     pub fn is_unnamed(&self) -> bool {
1782         match *self {
1783             UnnamedField(..) => true,
1784             NamedField(..) => false,
1785         }
1786     }
1787 }
1788
1789 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1790 pub struct StructDef {
1791     /// Fields, not including ctor
1792     pub fields: Vec<StructField>,
1793     /// ID of the constructor. This is only used for tuple- or enum-like
1794     /// structs.
1795     pub ctor_id: Option<NodeId>,
1796 }
1797
1798 /*
1799   FIXME (#3300): Should allow items to be anonymous. Right now
1800   we just use dummy names for anon items.
1801  */
1802 /// An item
1803 ///
1804 /// The name might be a dummy name in case of anonymous items
1805 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1806 pub struct Item {
1807     pub ident: Ident,
1808     pub attrs: Vec<Attribute>,
1809     pub id: NodeId,
1810     pub node: Item_,
1811     pub vis: Visibility,
1812     pub span: Span,
1813 }
1814
1815 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1816 pub enum Item_ {
1817     /// An`extern crate` item, with optional original crate name,
1818     ///
1819     /// e.g. `extern crate foo` or `extern crate foo_bar as foo`
1820     ItemExternCrate(Option<Name>),
1821     /// A `use` or `pub use` item
1822     ItemUse(P<ViewPath>),
1823
1824     /// A `static` item
1825     ItemStatic(P<Ty>, Mutability, P<Expr>),
1826     /// A `const` item
1827     ItemConst(P<Ty>, P<Expr>),
1828     /// A function declaration
1829     ItemFn(P<FnDecl>, Unsafety, Constness, Abi, Generics, P<Block>),
1830     /// A module
1831     ItemMod(Mod),
1832     /// An external module
1833     ItemForeignMod(ForeignMod),
1834     /// A type alias, e.g. `type Foo = Bar<u8>`
1835     ItemTy(P<Ty>, Generics),
1836     /// An enum definition, e.g. `enum Foo<A, B> {C<A>, D<B>}`
1837     ItemEnum(EnumDef, Generics),
1838     /// A struct definition, e.g. `struct Foo<A> {x: A}`
1839     ItemStruct(P<StructDef>, Generics),
1840     /// Represents a Trait Declaration
1841     ItemTrait(Unsafety,
1842               Generics,
1843               TyParamBounds,
1844               Vec<P<TraitItem>>),
1845
1846     // Default trait implementations
1847     ///
1848     // `impl Trait for .. {}`
1849     ItemDefaultImpl(Unsafety, TraitRef),
1850     /// An implementation, eg `impl<A> Trait for Foo { .. }`
1851     ItemImpl(Unsafety,
1852              ImplPolarity,
1853              Generics,
1854              Option<TraitRef>, // (optional) trait this impl implements
1855              P<Ty>, // self
1856              Vec<P<ImplItem>>),
1857     /// A macro invocation (which includes macro definition)
1858     ItemMac(Mac),
1859 }
1860
1861 impl Item_ {
1862     pub fn descriptive_variant(&self) -> &str {
1863         match *self {
1864             ItemExternCrate(..) => "extern crate",
1865             ItemUse(..) => "use",
1866             ItemStatic(..) => "static item",
1867             ItemConst(..) => "constant item",
1868             ItemFn(..) => "function",
1869             ItemMod(..) => "module",
1870             ItemForeignMod(..) => "foreign module",
1871             ItemTy(..) => "type alias",
1872             ItemEnum(..) => "enum",
1873             ItemStruct(..) => "struct",
1874             ItemTrait(..) => "trait",
1875             ItemMac(..) |
1876             ItemImpl(..) |
1877             ItemDefaultImpl(..) => "item"
1878         }
1879     }
1880 }
1881
1882 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1883 pub struct ForeignItem {
1884     pub ident: Ident,
1885     pub attrs: Vec<Attribute>,
1886     pub node: ForeignItem_,
1887     pub id: NodeId,
1888     pub span: Span,
1889     pub vis: Visibility,
1890 }
1891
1892 /// An item within an `extern` block
1893 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1894 pub enum ForeignItem_ {
1895     /// A foreign function
1896     ForeignItemFn(P<FnDecl>, Generics),
1897     /// A foreign static item (`static ext: u8`), with optional mutability
1898     /// (the boolean is true when mutable)
1899     ForeignItemStatic(P<Ty>, bool),
1900 }
1901
1902 impl ForeignItem_ {
1903     pub fn descriptive_variant(&self) -> &str {
1904         match *self {
1905             ForeignItemFn(..) => "foreign function",
1906             ForeignItemStatic(..) => "foreign static item"
1907         }
1908     }
1909 }
1910
1911 /// The data we save and restore about an inlined item or method.  This is not
1912 /// part of the AST that we parse from a file, but it becomes part of the tree
1913 /// that we trans.
1914 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1915 pub enum InlinedItem {
1916     IIItem(P<Item>),
1917     IITraitItem(DefId /* impl id */, P<TraitItem>),
1918     IIImplItem(DefId /* impl id */, P<ImplItem>),
1919     IIForeign(P<ForeignItem>),
1920 }
1921
1922 /// A macro definition, in this crate or imported from another.
1923 ///
1924 /// Not parsed directly, but created on macro import or `macro_rules!` expansion.
1925 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1926 pub struct MacroDef {
1927     pub ident: Ident,
1928     pub attrs: Vec<Attribute>,
1929     pub id: NodeId,
1930     pub span: Span,
1931     pub imported_from: Option<Ident>,
1932     pub export: bool,
1933     pub use_locally: bool,
1934     pub allow_internal_unstable: bool,
1935     pub body: Vec<TokenTree>,
1936 }
1937
1938 #[cfg(test)]
1939 mod tests {
1940     use serialize;
1941     use super::*;
1942
1943     // are ASTs encodable?
1944     #[test]
1945     fn check_asts_encodable() {
1946         fn assert_encodable<T: serialize::Encodable>() {}
1947         assert_encodable::<Crate>();
1948     }
1949 }