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::LocalSource::*;
  33 pub use self::Mac_::*;
  34 pub use self::MacStmtStyle::*;
  35 pub use self::MetaItem_::*;
  36 pub use self::Mutability::*;
  37 pub use self::Pat_::*;
  38 pub use self::PathListItem_::*;
  39 pub use self::PatWildKind::*;
  40 pub use self::PrimTy::*;
  41 pub use self::Sign::*;
  42 pub use self::Stmt_::*;
  43 pub use self::StrStyle::*;
  44 pub use self::StructFieldKind::*;
  45 pub use self::TokenTree::*;
  46 pub use self::TraitItem_::*;
  47 pub use self::Ty_::*;
  48 pub use self::TyParamBound::*;
  49 pub use self::UintTy::*;
  50 pub use self::UnOp::*;
  51 pub use self::UnsafeSource::*;
  52 pub use self::VariantKind::*;
  53 pub use self::ViewPath_::*;
  54 pub use self::Visibility::*;
  55 pub use self::PathParameters::*;
  56
  57 use codemap::{Span, Spanned, DUMMY_SP, ExpnId};
  58 use abi::Abi;
  59 use ast_util;
  60 use ext::base;
  61 use ext::tt::macro_parser;
  62 use owned_slice::OwnedSlice;
  63 use parse::token::{InternedString, str_to_ident};
  64 use parse::token;
  65 use parse::lexer;
  66 use ptr::P;
  67
  68 use std::fmt;
  69 use std::rc::Rc;
  70 use serialize::{Encodable, Decodable, Encoder, Decoder};
  71
  72 // FIXME #6993: in librustc, uses of "ident" should be replaced
  73 // by just "Name".
  74
  75 /// An identifier contains a Name (index into the interner
  76 /// table) and a SyntaxContext to track renaming and
  77 /// macro expansion per Flatt et al., "Macros
  78 /// That Work Together"
  79 #[derive(Clone, Copy, Hash, PartialOrd, Eq, Ord)]
  80 pub struct Ident {
  81     pub name: Name,
  82     pub ctxt: SyntaxContext
  83 }
  84
  85 impl Ident {
  86     /// Construct an identifier with the given name and an empty context:
  87     pub fn new(name: Name) -> Ident { Ident {name: name, ctxt: EMPTY_CTXT}}
  88
  89     pub fn as_str<'a>(&'a self) -> &'a str {
  90         self.name.as_str()
  91     }
  92
  93     pub fn encode_with_hygiene(&self) -> String {
  94         format!("\x00name_{},ctxt_{}\x00",
  95                 self.name.usize(),
  96                 self.ctxt)
  97     }
  98 }
  99
 100 impl fmt::Debug for Ident {
 101     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 102         write!(f, "{}#{}", self.name, self.ctxt)
 103     }
 104 }
 105
 106 impl fmt::Display for Ident {
 107     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 108         fmt::Display::fmt(&self.name, f)
 109     }
 110 }
 111
 112 impl fmt::Debug for Name {
 113     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 114         let Name(nm) = *self;
 115         write!(f, "{:?}({})", token::get_name(*self), nm)
 116     }
 117 }
 118
 119 impl fmt::Display for Name {
 120     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 121         fmt::Display::fmt(&token::get_name(*self), f)
 122     }
 123 }
 124
 125 impl PartialEq for Ident {
 126     fn eq(&self, other: &Ident) -> bool {
 127         if self.ctxt == other.ctxt {
 128             self.name == other.name
 129         } else {
 130             // IF YOU SEE ONE OF THESE FAILS: it means that you're comparing
 131             // idents that have different contexts. You can't fix this without
 132             // knowing whether the comparison should be hygienic or non-hygienic.
 133             // if it should be non-hygienic (most things are), just compare the
 134             // 'name' fields of the idents. Or, even better, replace the idents
 135             // with Name's.
 136             //
 137             // On the other hand, if the comparison does need to be hygienic,
 138             // one example and its non-hygienic counterpart would be:
 139             //      syntax::parse::token::Token::mtwt_eq
 140             //      syntax::ext::tt::macro_parser::token_name_eq
 141             panic!("not allowed to compare these idents: {}, {}. \
 142                    Probably related to issue \\#6993", self, other);
 143         }
 144     }
 145     fn ne(&self, other: &Ident) -> bool {
 146         ! self.eq(other)
 147     }
 148 }
 149
 150 /// A SyntaxContext represents a chain of macro-expandings
 151 /// and renamings. Each macro expansion corresponds to
 152 /// a fresh u32
 153
 154 // I'm representing this syntax context as an index into
 155 // a table, in order to work around a compiler bug
 156 // that's causing unreleased memory to cause core dumps
 157 // and also perhaps to save some work in destructor checks.
 158 // the special uint '0' will be used to indicate an empty
 159 // syntax context.
 160
 161 // this uint is a reference to a table stored in thread-local
 162 // storage.
 163 pub type SyntaxContext = u32;
 164 pub const EMPTY_CTXT : SyntaxContext = 0;
 165 pub const ILLEGAL_CTXT : SyntaxContext = 1;
 166
 167 /// A name is a part of an identifier, representing a string or gensym. It's
 168 /// the result of interning.
 169 #[derive(Eq, Ord, PartialEq, PartialOrd, Hash,
 170            RustcEncodable, RustcDecodable, Clone, Copy)]
 171 pub struct Name(pub u32);
 172
 173 impl Name {
 174     pub fn as_str<'a>(&'a self) -> &'a str {
 175         unsafe {
 176             // FIXME #12938: can't use copy_lifetime since &str isn't a &T
 177             ::std::mem::transmute::<&str,&str>(&token::get_name(*self))
 178         }
 179     }
 180
 181     pub fn usize(&self) -> usize {
 182         let Name(nm) = *self;
 183         nm as usize
 184     }
 185
 186     pub fn ident(&self) -> Ident {
 187         Ident { name: *self, ctxt: 0 }
 188     }
 189 }
 190
 191 /// A mark represents a unique id associated with a macro expansion
 192 pub type Mrk = u32;
 193
 194 impl Encodable for Ident {
 195     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
 196         s.emit_str(&token::get_ident(*self))
 197     }
 198 }
 199
 200 impl Decodable for Ident {
 201     fn decode<D: Decoder>(d: &mut D) -> Result<Ident, D::Error> {
 202         Ok(str_to_ident(&try!(d.read_str())[..]))
 203     }
 204 }
 205
 206 /// Function name (not all functions have names)
 207 pub type FnIdent = Option<Ident>;
 208
 209 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash,
 210            Debug, Copy)]
 211 pub struct Lifetime {
 212     pub id: NodeId,
 213     pub span: Span,
 214     pub name: Name
 215 }
 216
 217 /// A lifetime definition, eg `'a: 'b+'c+'d`
 218 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 219 pub struct LifetimeDef {
 220     pub lifetime: Lifetime,
 221     pub bounds: Vec<Lifetime>
 222 }
 223
 224 /// A "Path" is essentially Rust's notion of a name; for instance:
 225 /// std::cmp::PartialEq  .  It's represented as a sequence of identifiers,
 226 /// along with a bunch of supporting information.
 227 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 228 pub struct Path {
 229     pub span: Span,
 230     /// A `::foo` path, is relative to the crate root rather than current
 231     /// module (like paths in an import).
 232     pub global: bool,
 233     /// The segments in the path: the things separated by `::`.
 234     pub segments: Vec<PathSegment>,
 235 }
 236
 237 /// A segment of a path: an identifier, an optional lifetime, and a set of
 238 /// types.
 239 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 240 pub struct PathSegment {
 241     /// The identifier portion of this path segment.
 242     pub identifier: Ident,
 243
 244     /// Type/lifetime parameters attached to this path. They come in
 245     /// two flavors: `Path<A,B,C>` and `Path(A,B) -> C`. Note that
 246     /// this is more than just simple syntactic sugar; the use of
 247     /// parens affects the region binding rules, so we preserve the
 248     /// distinction.
 249     pub parameters: PathParameters,
 250 }
 251
 252 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 253 pub enum PathParameters {
 254     /// The `<'a, A,B,C>` in `foo::bar::baz::<'a, A,B,C>`
 255     AngleBracketedParameters(AngleBracketedParameterData),
 256     /// The `(A,B)` and `C` in `Foo(A,B) -> C`
 257     ParenthesizedParameters(ParenthesizedParameterData),
 258 }
 259
 260 impl PathParameters {
 261     pub fn none() -> PathParameters {
 262         AngleBracketedParameters(AngleBracketedParameterData {
 263             lifetimes: Vec::new(),
 264             types: OwnedSlice::empty(),
 265             bindings: OwnedSlice::empty(),
 266         })
 267     }
 268
 269     pub fn is_empty(&self) -> bool {
 270         match *self {
 271             AngleBracketedParameters(ref data) => data.is_empty(),
 272
 273             // Even if the user supplied no types, something like
 274             // `X()` is equivalent to `X<(),()>`.
 275             ParenthesizedParameters(..) => false,
 276         }
 277     }
 278
 279     pub fn has_lifetimes(&self) -> bool {
 280         match *self {
 281             AngleBracketedParameters(ref data) => !data.lifetimes.is_empty(),
 282             ParenthesizedParameters(_) => false,
 283         }
 284     }
 285
 286     pub fn has_types(&self) -> bool {
 287         match *self {
 288             AngleBracketedParameters(ref data) => !data.types.is_empty(),
 289             ParenthesizedParameters(..) => true,
 290         }
 291     }
 292
 293     /// Returns the types that the user wrote. Note that these do not necessarily map to the type
 294     /// parameters in the parenthesized case.
 295     pub fn types(&self) -> Vec<&P<Ty>> {
 296         match *self {
 297             AngleBracketedParameters(ref data) => {
 298                 data.types.iter().collect()
 299             }
 300             ParenthesizedParameters(ref data) => {
 301                 data.inputs.iter()
 302                     .chain(data.output.iter())
 303                     .collect()
 304             }
 305         }
 306     }
 307
 308     pub fn lifetimes(&self) -> Vec<&Lifetime> {
 309         match *self {
 310             AngleBracketedParameters(ref data) => {
 311                 data.lifetimes.iter().collect()
 312             }
 313             ParenthesizedParameters(_) => {
 314                 Vec::new()
 315             }
 316         }
 317     }
 318
 319     pub fn bindings(&self) -> Vec<&P<TypeBinding>> {
 320         match *self {
 321             AngleBracketedParameters(ref data) => {
 322                 data.bindings.iter().collect()
 323             }
 324             ParenthesizedParameters(_) => {
 325                 Vec::new()
 326             }
 327         }
 328     }
 329 }
 330
 331 /// A path like `Foo<'a, T>`
 332 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 333 pub struct AngleBracketedParameterData {
 334     /// The lifetime parameters for this path segment.
 335     pub lifetimes: Vec<Lifetime>,
 336     /// The type parameters for this path segment, if present.
 337     pub types: OwnedSlice<P<Ty>>,
 338     /// Bindings (equality constraints) on associated types, if present.
 339     /// E.g., `Foo<A=Bar>`.
 340     pub bindings: OwnedSlice<P<TypeBinding>>,
 341 }
 342
 343 impl AngleBracketedParameterData {
 344     fn is_empty(&self) -> bool {
 345         self.lifetimes.is_empty() && self.types.is_empty() && self.bindings.is_empty()
 346     }
 347 }
 348
 349 /// A path like `Foo(A,B) -> C`
 350 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 351 pub struct ParenthesizedParameterData {
 352     /// Overall span
 353     pub span: Span,
 354
 355     /// `(A,B)`
 356     pub inputs: Vec<P<Ty>>,
 357
 358     /// `C`
 359     pub output: Option<P<Ty>>,
 360 }
 361
 362 pub type CrateNum = u32;
 363
 364 pub type NodeId = u32;
 365
 366 #[derive(Clone, Eq, Ord, PartialOrd, PartialEq, RustcEncodable,
 367            RustcDecodable, Hash, Debug, Copy)]
 368 pub struct DefId {
 369     pub krate: CrateNum,
 370     pub node: NodeId,
 371 }
 372
 373 impl DefId {
 374     /// Read the node id, asserting that this def-id is krate-local.
 375     pub fn local_id(&self) -> NodeId {
 376         assert_eq!(self.krate, LOCAL_CRATE);
 377         self.node
 378     }
 379 }
 380
 381 /// Item definitions in the currently-compiled crate would have the CrateNum
 382 /// LOCAL_CRATE in their DefId.
 383 pub const LOCAL_CRATE: CrateNum = 0;
 384 pub const CRATE_NODE_ID: NodeId = 0;
 385
 386 /// When parsing and doing expansions, we initially give all AST nodes this AST
 387 /// node value. Then later, in the renumber pass, we renumber them to have
 388 /// small, positive ids.
 389 pub const DUMMY_NODE_ID: NodeId = !0;
 390
 391 /// The AST represents all type param bounds as types.
 392 /// typeck::collect::compute_bounds matches these against
 393 /// the "special" built-in traits (see middle::lang_items) and
 394 /// detects Copy, Send and Sync.
 395 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 396 pub enum TyParamBound {
 397     TraitTyParamBound(PolyTraitRef, TraitBoundModifier),
 398     RegionTyParamBound(Lifetime)
 399 }
 400
 401 /// A modifier on a bound, currently this is only used for `?Sized`, where the
 402 /// modifier is `Maybe`. Negative bounds should also be handled here.
 403 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 404 pub enum TraitBoundModifier {
 405     None,
 406     Maybe,
 407 }
 408
 409 pub type TyParamBounds = OwnedSlice<TyParamBound>;
 410
 411 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 412 pub struct TyParam {
 413     pub ident: Ident,
 414     pub id: NodeId,
 415     pub bounds: TyParamBounds,
 416     pub default: Option<P<Ty>>,
 417     pub span: Span
 418 }
 419
 420 /// Represents lifetimes and type parameters attached to a declaration
 421 /// of a function, enum, trait, etc.
 422 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 423 pub struct Generics {
 424     pub lifetimes: Vec<LifetimeDef>,
 425     pub ty_params: OwnedSlice<TyParam>,
 426     pub where_clause: WhereClause,
 427 }
 428
 429 impl Generics {
 430     pub fn is_lt_parameterized(&self) -> bool {
 431         !self.lifetimes.is_empty()
 432     }
 433     pub fn is_type_parameterized(&self) -> bool {
 434         !self.ty_params.is_empty()
 435     }
 436     pub fn is_parameterized(&self) -> bool {
 437         self.is_lt_parameterized() || self.is_type_parameterized()
 438     }
 439 }
 440
 441 /// A `where` clause in a definition
 442 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 443 pub struct WhereClause {
 444     pub id: NodeId,
 445     pub predicates: Vec<WherePredicate>,
 446 }
 447
 448 /// A single predicate in a `where` clause
 449 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 450 pub enum WherePredicate {
 451     /// A type binding, eg `for<'c> Foo: Send+Clone+'c`
 452     BoundPredicate(WhereBoundPredicate),
 453     /// A lifetime predicate, e.g. `'a: 'b+'c`
 454     RegionPredicate(WhereRegionPredicate),
 455     /// An equality predicate (unsupported)
 456     EqPredicate(WhereEqPredicate)
 457 }
 458
 459 /// A type bound, eg `for<'c> Foo: Send+Clone+'c`
 460 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 461 pub struct WhereBoundPredicate {
 462     pub span: Span,
 463     /// Any lifetimes from a `for` binding
 464     pub bound_lifetimes: Vec<LifetimeDef>,
 465     /// The type being bounded
 466     pub bounded_ty: P<Ty>,
 467     /// Trait and lifetime bounds (`Clone+Send+'static`)
 468     pub bounds: OwnedSlice<TyParamBound>,
 469 }
 470
 471 /// A lifetime predicate, e.g. `'a: 'b+'c`
 472 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 473 pub struct WhereRegionPredicate {
 474     pub span: Span,
 475     pub lifetime: Lifetime,
 476     pub bounds: Vec<Lifetime>,
 477 }
 478
 479 /// An equality predicate (unsupported), e.g. `T=int`
 480 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 481 pub struct WhereEqPredicate {
 482     pub id: NodeId,
 483     pub span: Span,
 484     pub path: Path,
 485     pub ty: P<Ty>,
 486 }
 487
 488 /// The set of MetaItems that define the compilation environment of the crate,
 489 /// used to drive conditional compilation
 490 pub type CrateConfig = Vec<P<MetaItem>> ;
 491
 492 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 493 pub struct Crate {
 494     pub module: Mod,
 495     pub attrs: Vec<Attribute>,
 496     pub config: CrateConfig,
 497     pub span: Span,
 498     pub exported_macros: Vec<MacroDef>,
 499 }
 500
 501 pub type MetaItem = Spanned<MetaItem_>;
 502
 503 #[derive(Clone, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 504 pub enum MetaItem_ {
 505     MetaWord(InternedString),
 506     MetaList(InternedString, Vec<P<MetaItem>>),
 507     MetaNameValue(InternedString, Lit),
 508 }
 509
 510 // can't be derived because the MetaList requires an unordered comparison
 511 impl PartialEq for MetaItem_ {
 512     fn eq(&self, other: &MetaItem_) -> bool {
 513         match *self {
 514             MetaWord(ref ns) => match *other {
 515                 MetaWord(ref no) => (*ns) == (*no),
 516                 _ => false
 517             },
 518             MetaNameValue(ref ns, ref vs) => match *other {
 519                 MetaNameValue(ref no, ref vo) => {
 520                     (*ns) == (*no) && vs.node == vo.node
 521                 }
 522                 _ => false
 523             },
 524             MetaList(ref ns, ref miss) => match *other {
 525                 MetaList(ref no, ref miso) => {
 526                     ns == no &&
 527                         miss.iter().all(|mi| miso.iter().any(|x| x.node == mi.node))
 528                 }
 529                 _ => false
 530             }
 531         }
 532     }
 533 }
 534
 535 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 536 pub struct Block {
 537     /// Statements in a block
 538     pub stmts: Vec<P<Stmt>>,
 539     /// An expression at the end of the block
 540     /// without a semicolon, if any
 541     pub expr: Option<P<Expr>>,
 542     pub id: NodeId,
 543     /// Distinguishes between `unsafe { ... }` and `{ ... }`
 544     pub rules: BlockCheckMode,
 545     pub span: Span,
 546 }
 547
 548 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 549 pub struct Pat {
 550     pub id: NodeId,
 551     pub node: Pat_,
 552     pub span: Span,
 553 }
 554
 555 /// A single field in a struct pattern
 556 ///
 557 /// Patterns like the fields of Foo `{ x, ref y, ref mut z }`
 558 /// are treated the same as` x: x, y: ref y, z: ref mut z`,
 559 /// except is_shorthand is true
 560 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 561 pub struct FieldPat {
 562     /// The identifier for the field
 563     pub ident: Ident,
 564     /// The pattern the field is destructured to
 565     pub pat: P<Pat>,
 566     pub is_shorthand: bool,
 567 }
 568
 569 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 570 pub enum BindingMode {
 571     BindByRef(Mutability),
 572     BindByValue(Mutability),
 573 }
 574
 575 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 576 pub enum PatWildKind {
 577     /// Represents the wildcard pattern `_`
 578     PatWildSingle,
 579
 580     /// Represents the wildcard pattern `..`
 581     PatWildMulti,
 582 }
 583
 584 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 585 pub enum Pat_ {
 586     /// Represents a wildcard pattern (either `_` or `..`)
 587     PatWild(PatWildKind),
 588
 589     /// A PatIdent may either be a new bound variable,
 590     /// or a nullary enum (in which case the third field
 591     /// is None).
 592     ///
 593     /// In the nullary enum case, the parser can't determine
 594     /// which it is. The resolver determines this, and
 595     /// records this pattern's NodeId in an auxiliary
 596     /// set (of "PatIdents that refer to nullary enums")
 597     PatIdent(BindingMode, SpannedIdent, Option<P<Pat>>),
 598
 599     /// "None" means a * pattern where we don't bind the fields to names.
 600     PatEnum(Path, Option<Vec<P<Pat>>>),
 601
 602     /// Destructuring of a struct, e.g. `Foo {x, y, ..}`
 603     /// The `bool` is `true` in the presence of a `..`
 604     PatStruct(Path, Vec<Spanned<FieldPat>>, bool),
 605     /// A tuple pattern `(a, b)`
 606     PatTup(Vec<P<Pat>>),
 607     /// A `box` pattern
 608     PatBox(P<Pat>),
 609     /// A reference pattern, e.g. `&mut (a, b)`
 610     PatRegion(P<Pat>, Mutability),
 611     /// A literal
 612     PatLit(P<Expr>),
 613     /// A range pattern, e.g. `1...2`
 614     PatRange(P<Expr>, P<Expr>),
 615     /// [a, b, ..i, y, z] is represented as:
 616     ///     PatVec(box [a, b], Some(i), box [y, z])
 617     PatVec(Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>),
 618     /// A macro pattern; pre-expansion
 619     PatMac(Mac),
 620 }
 621
 622 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 623 pub enum Mutability {
 624     MutMutable,
 625     MutImmutable,
 626 }
 627
 628 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 629 pub enum BinOp_ {
 630     /// The `+` operator (addition)
 631     BiAdd,
 632     /// The `-` operator (subtraction)
 633     BiSub,
 634     /// The `*` operator (multiplication)
 635     BiMul,
 636     /// The `/` operator (division)
 637     BiDiv,
 638     /// The `%` operator (modulus)
 639     BiRem,
 640     /// The `&&` operator (logical and)
 641     BiAnd,
 642     /// The `||` operator (logical or)
 643     BiOr,
 644     /// The `^` operator (bitwise xor)
 645     BiBitXor,
 646     /// The `&` operator (bitwise and)
 647     BiBitAnd,
 648     /// The `|` operator (bitwise or)
 649     BiBitOr,
 650     /// The `<<` operator (shift left)
 651     BiShl,
 652     /// The `>>` operator (shift right)
 653     BiShr,
 654     /// The `==` operator (equality)
 655     BiEq,
 656     /// The `<` operator (less than)
 657     BiLt,
 658     /// The `<=` operator (less than or equal to)
 659     BiLe,
 660     /// The `!=` operator (not equal to)
 661     BiNe,
 662     /// The `>=` operator (greater than or equal to)
 663     BiGe,
 664     /// The `>` operator (greater than)
 665     BiGt,
 666 }
 667
 668 pub type BinOp = Spanned<BinOp_>;
 669
 670 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 671 pub enum UnOp {
 672     /// The `box` operator
 673     UnUniq,
 674     /// The `*` operator for dereferencing
 675     UnDeref,
 676     /// The `!` operator for logical inversion
 677     UnNot,
 678     /// The `-` operator for negation
 679     UnNeg
 680 }
 681
 682 /// A statement
 683 pub type Stmt = Spanned<Stmt_>;
 684
 685 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 686 pub enum Stmt_ {
 687     /// Could be an item or a local (let) binding:
 688     StmtDecl(P<Decl>, NodeId),
 689
 690     /// Expr without trailing semi-colon (must have unit type):
 691     StmtExpr(P<Expr>, NodeId),
 692
 693     /// Expr with trailing semi-colon (may have any type):
 694     StmtSemi(P<Expr>, NodeId),
 695
 696     StmtMac(P<Mac>, MacStmtStyle),
 697 }
 698
 699 #[derive(Clone, Copy, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 700 pub enum MacStmtStyle {
 701     /// The macro statement had a trailing semicolon, e.g. `foo! { ... };`
 702     /// `foo!(...);`, `foo![...];`
 703     MacStmtWithSemicolon,
 704     /// The macro statement had braces; e.g. foo! { ... }
 705     MacStmtWithBraces,
 706     /// The macro statement had parentheses or brackets and no semicolon; e.g.
 707     /// `foo!(...)`. All of these will end up being converted into macro
 708     /// expressions.
 709     MacStmtWithoutBraces,
 710 }
 711
 712 /// Where a local declaration came from: either a true `let ... =
 713 /// ...;`, or one desugared from the pattern of a for loop.
 714 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 715 pub enum LocalSource {
 716     LocalLet,
 717     LocalFor,
 718 }
 719
 720 // FIXME (pending discussion of #1697, #2178...): local should really be
 721 // a refinement on pat.
 722 /// Local represents a `let` statement, e.g., `let <pat>:<ty> = <expr>;`
 723 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 724 pub struct Local {
 725     pub pat: P<Pat>,
 726     pub ty: Option<P<Ty>>,
 727     /// Initializer expression to set the value, if any
 728     pub init: Option<P<Expr>>,
 729     pub id: NodeId,
 730     pub span: Span,
 731     pub source: LocalSource,
 732 }
 733
 734 pub type Decl = Spanned<Decl_>;
 735
 736 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 737 pub enum Decl_ {
 738     /// A local (let) binding:
 739     DeclLocal(P<Local>),
 740     /// An item binding:
 741     DeclItem(P<Item>),
 742 }
 743
 744 /// represents one arm of a 'match'
 745 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 746 pub struct Arm {
 747     pub attrs: Vec<Attribute>,
 748     pub pats: Vec<P<Pat>>,
 749     pub guard: Option<P<Expr>>,
 750     pub body: P<Expr>,
 751 }
 752
 753 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 754 pub struct Field {
 755     pub ident: SpannedIdent,
 756     pub expr: P<Expr>,
 757     pub span: Span,
 758 }
 759
 760 pub type SpannedIdent = Spanned<Ident>;
 761
 762 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 763 pub enum BlockCheckMode {
 764     DefaultBlock,
 765     UnsafeBlock(UnsafeSource),
 766 }
 767
 768 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 769 pub enum UnsafeSource {
 770     CompilerGenerated,
 771     UserProvided,
 772 }
 773
 774 /// An expression
 775 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 776 pub struct Expr {
 777     pub id: NodeId,
 778     pub node: Expr_,
 779     pub span: Span,
 780 }
 781
 782 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 783 pub enum Expr_ {
 784     /// First expr is the place; second expr is the value.
 785     ExprBox(Option<P<Expr>>, P<Expr>),
 786     /// An array (`[a, b, c, d]`)
 787     ExprVec(Vec<P<Expr>>),
 788     /// A function call
 789     ///
 790     /// The first field resolves to the function itself,
 791     /// and the second field is the list of arguments
 792     ExprCall(P<Expr>, Vec<P<Expr>>),
 793     /// A method call (`x.foo::<Bar, Baz>(a, b, c, d)`)
 794     ///
 795     /// The `SpannedIdent` is the identifier for the method name.
 796     /// The vector of `Ty`s are the ascripted type parameters for the method
 797     /// (within the angle brackets).
 798     ///
 799     /// The first element of the vector of `Expr`s is the expression that evaluates
 800     /// to the object on which the method is being called on (the receiver),
 801     /// and the remaining elements are the rest of the arguments.
 802     ///
 803     /// Thus, `x.foo::<Bar, Baz>(a, b, c, d)` is represented as
 804     /// `ExprMethodCall(foo, [Bar, Baz], [x, a, b, c, d])`.
 805     ExprMethodCall(SpannedIdent, Vec<P<Ty>>, Vec<P<Expr>>),
 806     /// A tuple (`(a, b, c ,d)`)
 807     ExprTup(Vec<P<Expr>>),
 808     /// A binary operation (For example: `a + b`, `a * b`)
 809     ExprBinary(BinOp, P<Expr>, P<Expr>),
 810     /// A unary operation (For example: `!x`, `*x`)
 811     ExprUnary(UnOp, P<Expr>),
 812     /// A literal (For example: `1u8`, `"foo"`)
 813     ExprLit(P<Lit>),
 814     /// A cast (`foo as f64`)
 815     ExprCast(P<Expr>, P<Ty>),
 816     /// An `if` block, with an optional else block
 817     ///
 818     /// `if expr { block } else { expr }`
 819     ExprIf(P<Expr>, P<Block>, Option<P<Expr>>),
 820     /// An `if let` expression with an optional else block
 821     ///
 822     /// `if let pat = expr { block } else { expr }`
 823     ///
 824     /// This is desugared to a `match` expression.
 825     ExprIfLet(P<Pat>, P<Expr>, P<Block>, Option<P<Expr>>),
 826     // FIXME #6993: change to Option<Name> ... or not, if these are hygienic.
 827     /// A while loop, with an optional label
 828     ///
 829     /// `'label: while expr { block }`
 830     ExprWhile(P<Expr>, P<Block>, Option<Ident>),
 831     // FIXME #6993: change to Option<Name> ... or not, if these are hygienic.
 832     /// A while-let loop, with an optional label
 833     ///
 834     /// `'label: while let pat = expr { block }`
 835     ///
 836     /// This is desugared to a combination of `loop` and `match` expressions.
 837     ExprWhileLet(P<Pat>, P<Expr>, P<Block>, Option<Ident>),
 838     // FIXME #6993: change to Option<Name> ... or not, if these are hygienic.
 839     /// A for loop, with an optional label
 840     ///
 841     /// `'label: for pat in expr { block }`
 842     ///
 843     /// This is desugared to a combination of `loop` and `match` expressions.
 844     ExprForLoop(P<Pat>, P<Expr>, P<Block>, Option<Ident>),
 845     /// Conditionless loop (can be exited with break, continue, or return)
 846     ///
 847     /// `'label: loop { block }`
 848     // FIXME #6993: change to Option<Name> ... or not, if these are hygienic.
 849     ExprLoop(P<Block>, Option<Ident>),
 850     /// A `match` block, with a source that indicates whether or not it is
 851     /// the result of a desugaring, and if so, which kind.
 852     ExprMatch(P<Expr>, Vec<Arm>, MatchSource),
 853     /// A closure (for example, `move |a, b, c| {a + b + c}`)
 854     ExprClosure(CaptureClause, P<FnDecl>, P<Block>),
 855     /// A block (`{ ... }`)
 856     ExprBlock(P<Block>),
 857
 858     /// An assignment (`a = foo()`)
 859     ExprAssign(P<Expr>, P<Expr>),
 860     /// An assignment with an operator
 861     ///
 862     /// For example, `a += 1`.
 863     ExprAssignOp(BinOp, P<Expr>, P<Expr>),
 864     /// Access of a named struct field (`obj.foo`)
 865     ExprField(P<Expr>, SpannedIdent),
 866     /// Access of an unnamed field of a struct or tuple-struct
 867     ///
 868     /// For example, `foo.0`.
 869     ExprTupField(P<Expr>, Spanned<usize>),
 870     /// An indexing operation (`foo[2]`)
 871     ExprIndex(P<Expr>, P<Expr>),
 872     /// A range (`1..2`, `1..`, or `..2`)
 873     ExprRange(Option<P<Expr>>, Option<P<Expr>>),
 874
 875     /// Variable reference, possibly containing `::` and/or type
 876     /// parameters, e.g. foo::bar::<baz>.
 877     ///
 878     /// Optionally "qualified",
 879     /// e.g. `<Vec<T> as SomeTrait>::SomeType`.
 880     ExprPath(Option<QSelf>, Path),
 881
 882     /// A referencing operation (`&a` or `&mut a`)
 883     ExprAddrOf(Mutability, P<Expr>),
 884     /// A `break`, with an optional label to break
 885     ExprBreak(Option<Ident>),
 886     /// A `continue`, with an optional label
 887     ExprAgain(Option<Ident>),
 888     /// A `return`, with an optional value to be returned
 889     ExprRet(Option<P<Expr>>),
 890
 891     /// Output of the `asm!()` macro
 892     ExprInlineAsm(InlineAsm),
 893
 894     /// A macro invocation; pre-expansion
 895     ExprMac(Mac),
 896
 897     /// A struct literal expression.
 898     ///
 899     /// For example, `Foo {x: 1, y: 2}`, or
 900     /// `Foo {x: 1, .. base}`, where `base` is the `Option<Expr>`.
 901     ExprStruct(Path, Vec<Field>, Option<P<Expr>>),
 902
 903     /// A vector literal constructed from one repeated element.
 904     ///
 905     /// For example, `[1u8; 5]`. The first expression is the element
 906     /// to be repeated; the second is the number of times to repeat it.
 907     ExprRepeat(P<Expr>, P<Expr>),
 908
 909     /// No-op: used solely so we can pretty-print faithfully
 910     ExprParen(P<Expr>)
 911 }
 912
 913 /// The explicit Self type in a "qualified path". The actual
 914 /// path, including the trait and the associated item, is stored
 915 /// separately. `position` represents the index of the associated
 916 /// item qualified with this Self type.
 917 ///
 918 ///     <Vec<T> as a::b::Trait>::AssociatedItem
 919 ///      ^~~~~     ~~~~~~~~~~~~~~^
 920 ///      ty        position = 3
 921 ///
 922 ///     <Vec<T>>::AssociatedItem
 923 ///      ^~~~~    ^
 924 ///      ty       position = 0
 925 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 926 pub struct QSelf {
 927     pub ty: P<Ty>,
 928     pub position: usize
 929 }
 930
 931 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 932 pub enum MatchSource {
 933     Normal,
 934     IfLetDesugar { contains_else_clause: bool },
 935     WhileLetDesugar,
 936     ForLoopDesugar,
 937 }
 938
 939 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 940 pub enum CaptureClause {
 941     CaptureByValue,
 942     CaptureByRef,
 943 }
 944
 945 /// A delimited sequence of token trees
 946 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 947 pub struct Delimited {
 948     /// The type of delimiter
 949     pub delim: token::DelimToken,
 950     /// The span covering the opening delimiter
 951     pub open_span: Span,
 952     /// The delimited sequence of token trees
 953     pub tts: Vec<TokenTree>,
 954     /// The span covering the closing delimiter
 955     pub close_span: Span,
 956 }
 957
 958 impl Delimited {
 959     /// Returns the opening delimiter as a token.
 960     pub fn open_token(&self) -> token::Token {
 961         token::OpenDelim(self.delim)
 962     }
 963
 964     /// Returns the closing delimiter as a token.
 965     pub fn close_token(&self) -> token::Token {
 966         token::CloseDelim(self.delim)
 967     }
 968
 969     /// Returns the opening delimiter as a token tree.
 970     pub fn open_tt(&self) -> TokenTree {
 971         TtToken(self.open_span, self.open_token())
 972     }
 973
 974     /// Returns the closing delimiter as a token tree.
 975     pub fn close_tt(&self) -> TokenTree {
 976         TtToken(self.close_span, self.close_token())
 977     }
 978 }
 979
 980 /// A sequence of token treesee
 981 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 982 pub struct SequenceRepetition {
 983     /// The sequence of token trees
 984     pub tts: Vec<TokenTree>,
 985     /// The optional separator
 986     pub separator: Option<token::Token>,
 987     /// Whether the sequence can be repeated zero (*), or one or more times (+)
 988     pub op: KleeneOp,
 989     /// The number of `MatchNt`s that appear in the sequence (and subsequences)
 990     pub num_captures: usize,
 991 }
 992
 993 /// A Kleene-style [repetition operator](http://en.wikipedia.org/wiki/Kleene_star)
 994 /// for token sequences.
 995 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 996 pub enum KleeneOp {
 997     ZeroOrMore,
 998     OneOrMore,
 999 }
1000
1001 /// When the main rust parser encounters a syntax-extension invocation, it
1002 /// parses the arguments to the invocation as a token-tree. This is a very
1003 /// loose structure, such that all sorts of different AST-fragments can
1004 /// be passed to syntax extensions using a uniform type.
1005 ///
1006 /// If the syntax extension is an MBE macro, it will attempt to match its
1007 /// LHS token tree against the provided token tree, and if it finds a
1008 /// match, will transcribe the RHS token tree, splicing in any captured
1009 /// macro_parser::matched_nonterminals into the `SubstNt`s it finds.
1010 ///
1011 /// The RHS of an MBE macro is the only place `SubstNt`s are substituted.
1012 /// Nothing special happens to misnamed or misplaced `SubstNt`s.
1013 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1014 pub enum TokenTree {
1015     /// A single token
1016     TtToken(Span, token::Token),
1017     /// A delimited sequence of token trees
1018     TtDelimited(Span, Rc<Delimited>),
1019
1020     // This only makes sense in MBE macros.
1021
1022     /// A kleene-style repetition sequence with a span
1023     // FIXME(eddyb) #12938 Use DST.
1024     TtSequence(Span, Rc<SequenceRepetition>),
1025 }
1026
1027 impl TokenTree {
1028     pub fn len(&self) -> usize {
1029         match *self {
1030             TtToken(_, token::DocComment(_)) => 2,
1031             TtToken(_, token::SpecialVarNt(..)) => 2,
1032             TtToken(_, token::MatchNt(..)) => 3,
1033             TtDelimited(_, ref delimed) => {
1034                 delimed.tts.len() + 2
1035             }
1036             TtSequence(_, ref seq) => {
1037                 seq.tts.len()
1038             }
1039             TtToken(..) => 0
1040         }
1041     }
1042
1043     pub fn get_tt(&self, index: usize) -> TokenTree {
1044         match (self, index) {
1045             (&TtToken(sp, token::DocComment(_)), 0) => {
1046                 TtToken(sp, token::Pound)
1047             }
1048             (&TtToken(sp, token::DocComment(name)), 1) => {
1049                 TtDelimited(sp, Rc::new(Delimited {
1050                     delim: token::Bracket,
1051                     open_span: sp,
1052                     tts: vec![TtToken(sp, token::Ident(token::str_to_ident("doc"),
1053                                                        token::Plain)),
1054                               TtToken(sp, token::Eq),
1055                               TtToken(sp, token::Literal(token::Str_(name), None))],
1056                     close_span: sp,
1057                 }))
1058             }
1059             (&TtDelimited(_, ref delimed), _) => {
1060                 if index == 0 {
1061                     return delimed.open_tt();
1062                 }
1063                 if index == delimed.tts.len() + 1 {
1064                     return delimed.close_tt();
1065                 }
1066                 delimed.tts[index - 1].clone()
1067             }
1068             (&TtToken(sp, token::SpecialVarNt(var)), _) => {
1069                 let v = [TtToken(sp, token::Dollar),
1070                          TtToken(sp, token::Ident(token::str_to_ident(var.as_str()),
1071                                                   token::Plain))];
1072                 v[index].clone()
1073             }
1074             (&TtToken(sp, token::MatchNt(name, kind, name_st, kind_st)), _) => {
1075                 let v = [TtToken(sp, token::SubstNt(name, name_st)),
1076                          TtToken(sp, token::Colon),
1077                          TtToken(sp, token::Ident(kind, kind_st))];
1078                 v[index].clone()
1079             }
1080             (&TtSequence(_, ref seq), _) => {
1081                 seq.tts[index].clone()
1082             }
1083             _ => panic!("Cannot expand a token tree")
1084         }
1085     }
1086
1087     /// Returns the `Span` corresponding to this token tree.
1088     pub fn get_span(&self) -> Span {
1089         match *self {
1090             TtToken(span, _)     => span,
1091             TtDelimited(span, _) => span,
1092             TtSequence(span, _)  => span,
1093         }
1094     }
1095
1096     /// Use this token tree as a matcher to parse given tts.
1097     pub fn parse(cx: &base::ExtCtxt, mtch: &[TokenTree], tts: &[TokenTree])
1098                  -> macro_parser::NamedParseResult {
1099         // `None` is because we're not interpolating
1100         let arg_rdr = lexer::new_tt_reader_with_doc_flag(&cx.parse_sess().span_diagnostic,
1101                                                          None,
1102                                                          None,
1103                                                          tts.iter().cloned().collect(),
1104                                                          true);
1105         macro_parser::parse(cx.parse_sess(), cx.cfg(), arg_rdr, mtch)
1106     }
1107 }
1108
1109 pub type Mac = Spanned<Mac_>;
1110
1111 /// Represents a macro invocation. The Path indicates which macro
1112 /// is being invoked, and the vector of token-trees contains the source
1113 /// of the macro invocation.
1114 ///
1115 /// There's only one flavor, now, so this could presumably be simplified.
1116 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1117 pub enum Mac_ {
1118     // NB: the additional ident for a macro_rules-style macro is actually
1119     // stored in the enclosing item. Oog.
1120     MacInvocTT(Path, Vec<TokenTree>, SyntaxContext),   // new macro-invocation
1121 }
1122
1123 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1124 pub enum StrStyle {
1125     /// A regular string, like `"foo"`
1126     CookedStr,
1127     /// A raw string, like `r##"foo"##`
1128     ///
1129     /// The uint is the number of `#` symbols used
1130     RawStr(usize)
1131 }
1132
1133 /// A literal
1134 pub type Lit = Spanned<Lit_>;
1135
1136 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1137 pub enum Sign {
1138     Minus,
1139     Plus
1140 }
1141
1142 impl Sign {
1143     pub fn new<T: IntSign>(n: T) -> Sign {
1144         n.sign()
1145     }
1146 }
1147
1148 pub trait IntSign {
1149     fn sign(&self) -> Sign;
1150 }
1151 macro_rules! doit {
1152     ($($t:ident)*) => ($(impl IntSign for $t {
1153         #[allow(unused_comparisons)]
1154         fn sign(&self) -> Sign {
1155             if *self < 0 {Minus} else {Plus}
1156         }
1157     })*)
1158 }
1159 doit! { i8 i16 i32 i64 isize u8 u16 u32 u64 usize }
1160
1161 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1162 pub enum LitIntType {
1163     SignedIntLit(IntTy, Sign),
1164     UnsignedIntLit(UintTy),
1165     UnsuffixedIntLit(Sign)
1166 }
1167
1168 impl LitIntType {
1169     pub fn suffix_len(&self) -> usize {
1170         match *self {
1171             UnsuffixedIntLit(_) => 0,
1172             SignedIntLit(s, _) => s.suffix_len(),
1173             UnsignedIntLit(u) => u.suffix_len()
1174         }
1175     }
1176 }
1177
1178 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1179 pub enum Lit_ {
1180     /// A string literal (`"foo"`)
1181     LitStr(InternedString, StrStyle),
1182     /// A byte string (`b"foo"`)
1183     LitBinary(Rc<Vec<u8>>),
1184     /// A byte char (`b'f'`)
1185     LitByte(u8),
1186     /// A character literal (`'a'`)
1187     LitChar(char),
1188     /// An integer literal (`1u8`)
1189     LitInt(u64, LitIntType),
1190     /// A float literal (`1f64` or `1E10f64`)
1191     LitFloat(InternedString, FloatTy),
1192     /// A float literal without a suffix (`1.0 or 1.0E10`)
1193     LitFloatUnsuffixed(InternedString),
1194     /// A boolean literal
1195     LitBool(bool),
1196 }
1197
1198 // NB: If you change this, you'll probably want to change the corresponding
1199 // type structure in middle/ty.rs as well.
1200 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1201 pub struct MutTy {
1202     pub ty: P<Ty>,
1203     pub mutbl: Mutability,
1204 }
1205
1206 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1207 pub struct TypeField {
1208     pub ident: Ident,
1209     pub mt: MutTy,
1210     pub span: Span,
1211 }
1212
1213 /// Represents a method's signature in a trait declaration,
1214 /// or in an implementation.
1215 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1216 pub struct MethodSig {
1217     pub unsafety: Unsafety,
1218     pub abi: Abi,
1219     pub decl: P<FnDecl>,
1220     pub generics: Generics,
1221     pub explicit_self: ExplicitSelf,
1222 }
1223
1224 /// Represents a method declaration in a trait declaration, possibly including
1225 /// a default implementation A trait method is either required (meaning it
1226 /// doesn't have an implementation, just a signature) or provided (meaning it
1227 /// has a default implementation).
1228 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1229 pub struct TraitItem {
1230     pub id: NodeId,
1231     pub ident: Ident,
1232     pub attrs: Vec<Attribute>,
1233     pub node: TraitItem_,
1234     pub span: Span,
1235 }
1236
1237 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1238 pub enum TraitItem_ {
1239     MethodTraitItem(MethodSig, Option<P<Block>>),
1240     TypeTraitItem(TyParamBounds, Option<P<Ty>>),
1241 }
1242
1243 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1244 pub struct ImplItem {
1245     pub id: NodeId,
1246     pub ident: Ident,
1247     pub vis: Visibility,
1248     pub attrs: Vec<Attribute>,
1249     pub node: ImplItem_,
1250     pub span: Span,
1251 }
1252
1253 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1254 pub enum ImplItem_ {
1255     MethodImplItem(MethodSig, P<Block>),
1256     TypeImplItem(P<Ty>),
1257     MacImplItem(Mac),
1258 }
1259
1260 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
1261 pub enum IntTy {
1262     TyIs,
1263     TyI8,
1264     TyI16,
1265     TyI32,
1266     TyI64,
1267 }
1268
1269 impl fmt::Debug for IntTy {
1270     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1271         fmt::Display::fmt(self, f)
1272     }
1273 }
1274
1275 impl fmt::Display for IntTy {
1276     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1277         write!(f, "{}", ast_util::int_ty_to_string(*self, None))
1278     }
1279 }
1280
1281 impl IntTy {
1282     pub fn suffix_len(&self) -> usize {
1283         match *self {
1284             TyIs | TyI8 => 2,
1285             TyI16 | TyI32 | TyI64  => 3,
1286         }
1287     }
1288 }
1289
1290 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
1291 pub enum UintTy {
1292     TyUs,
1293     TyU8,
1294     TyU16,
1295     TyU32,
1296     TyU64,
1297 }
1298
1299 impl UintTy {
1300     pub fn suffix_len(&self) -> usize {
1301         match *self {
1302             TyUs | TyU8 => 2,
1303             TyU16 | TyU32 | TyU64  => 3,
1304         }
1305     }
1306 }
1307
1308 impl fmt::Debug for UintTy {
1309     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1310         fmt::Display::fmt(self, f)
1311     }
1312 }
1313
1314 impl fmt::Display for UintTy {
1315     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1316         write!(f, "{}", ast_util::uint_ty_to_string(*self, None))
1317     }
1318 }
1319
1320 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
1321 pub enum FloatTy {
1322     TyF32,
1323     TyF64,
1324 }
1325
1326 impl fmt::Debug for FloatTy {
1327     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1328         fmt::Display::fmt(self, f)
1329     }
1330 }
1331
1332 impl fmt::Display for FloatTy {
1333     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1334         write!(f, "{}", ast_util::float_ty_to_string(*self))
1335     }
1336 }
1337
1338 impl FloatTy {
1339     pub fn suffix_len(&self) -> usize {
1340         match *self {
1341             TyF32 | TyF64 => 3, // add F128 handling here
1342         }
1343     }
1344 }
1345
1346 // Bind a type to an associated type: `A=Foo`.
1347 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1348 pub struct TypeBinding {
1349     pub id: NodeId,
1350     pub ident: Ident,
1351     pub ty: P<Ty>,
1352     pub span: Span,
1353 }
1354
1355
1356 // NB PartialEq method appears below.
1357 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1358 pub struct Ty {
1359     pub id: NodeId,
1360     pub node: Ty_,
1361     pub span: Span,
1362 }
1363
1364 /// Not represented directly in the AST, referred to by name through a ty_path.
1365 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1366 pub enum PrimTy {
1367     TyInt(IntTy),
1368     TyUint(UintTy),
1369     TyFloat(FloatTy),
1370     TyStr,
1371     TyBool,
1372     TyChar
1373 }
1374
1375 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1376 pub struct BareFnTy {
1377     pub unsafety: Unsafety,
1378     pub abi: Abi,
1379     pub lifetimes: Vec<LifetimeDef>,
1380     pub decl: P<FnDecl>
1381 }
1382
1383 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1384 /// The different kinds of types recognized by the compiler
1385 pub enum Ty_ {
1386     TyVec(P<Ty>),
1387     /// A fixed length array (`[T; n]`)
1388     TyFixedLengthVec(P<Ty>, P<Expr>),
1389     /// A raw pointer (`*const T` or `*mut T`)
1390     TyPtr(MutTy),
1391     /// A reference (`&'a T` or `&'a mut T`)
1392     TyRptr(Option<Lifetime>, MutTy),
1393     /// A bare function (e.g. `fn(usize) -> bool`)
1394     TyBareFn(P<BareFnTy>),
1395     /// A tuple (`(A, B, C, D,...)`)
1396     TyTup(Vec<P<Ty>> ),
1397     /// A path (`module::module::...::Type`), optionally
1398     /// "qualified", e.g. `<Vec<T> as SomeTrait>::SomeType`.
1399     ///
1400     /// Type parameters are stored in the Path itself
1401     TyPath(Option<QSelf>, Path),
1402     /// Something like `A+B`. Note that `B` must always be a path.
1403     TyObjectSum(P<Ty>, TyParamBounds),
1404     /// A type like `for<'a> Foo<&'a Bar>`
1405     TyPolyTraitRef(TyParamBounds),
1406     /// No-op; kept solely so that we can pretty-print faithfully
1407     TyParen(P<Ty>),
1408     /// Unused for now
1409     TyTypeof(P<Expr>),
1410     /// TyInfer means the type should be inferred instead of it having been
1411     /// specified. This can appear anywhere in a type.
1412     TyInfer,
1413 }
1414
1415 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1416 pub enum AsmDialect {
1417     AsmAtt,
1418     AsmIntel
1419 }
1420
1421 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1422 pub struct InlineAsm {
1423     pub asm: InternedString,
1424     pub asm_str_style: StrStyle,
1425     pub outputs: Vec<(InternedString, P<Expr>, bool)>,
1426     pub inputs: Vec<(InternedString, P<Expr>)>,
1427     pub clobbers: Vec<InternedString>,
1428     pub volatile: bool,
1429     pub alignstack: bool,
1430     pub dialect: AsmDialect,
1431     pub expn_id: ExpnId,
1432 }
1433
1434 /// represents an argument in a function header
1435 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1436 pub struct Arg {
1437     pub ty: P<Ty>,
1438     pub pat: P<Pat>,
1439     pub id: NodeId,
1440 }
1441
1442 impl Arg {
1443     pub fn new_self(span: Span, mutability: Mutability, self_ident: Ident) -> Arg {
1444         let path = Spanned{span:span,node:self_ident};
1445         Arg {
1446             // HACK(eddyb) fake type for the self argument.
1447             ty: P(Ty {
1448                 id: DUMMY_NODE_ID,
1449                 node: TyInfer,
1450                 span: DUMMY_SP,
1451             }),
1452             pat: P(Pat {
1453                 id: DUMMY_NODE_ID,
1454                 node: PatIdent(BindByValue(mutability), path, None),
1455                 span: span
1456             }),
1457             id: DUMMY_NODE_ID
1458         }
1459     }
1460 }
1461
1462 /// Represents the header (not the body) of a function declaration
1463 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1464 pub struct FnDecl {
1465     pub inputs: Vec<Arg>,
1466     pub output: FunctionRetTy,
1467     pub variadic: bool
1468 }
1469
1470 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1471 pub enum Unsafety {
1472     Unsafe,
1473     Normal,
1474 }
1475
1476 impl fmt::Display for Unsafety {
1477     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1478         fmt::Display::fmt(match *self {
1479             Unsafety::Normal => "normal",
1480             Unsafety::Unsafe => "unsafe",
1481         }, f)
1482     }
1483 }
1484
1485 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
1486 pub enum ImplPolarity {
1487     /// `impl Trait for Type`
1488     Positive,
1489     /// `impl !Trait for Type`
1490     Negative,
1491 }
1492
1493 impl fmt::Debug for ImplPolarity {
1494     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1495         match *self {
1496             ImplPolarity::Positive => "positive".fmt(f),
1497             ImplPolarity::Negative => "negative".fmt(f),
1498         }
1499     }
1500 }
1501
1502
1503 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1504 pub enum FunctionRetTy {
1505     /// Functions with return type `!`that always
1506     /// raise an error or exit (i.e. never return to the caller)
1507     NoReturn(Span),
1508     /// Return type is not specified.
1509     ///
1510     /// Functions default to `()` and
1511     /// closures default to inference. Span points to where return
1512     /// type would be inserted.
1513     DefaultReturn(Span),
1514     /// Everything else
1515     Return(P<Ty>),
1516 }
1517
1518 impl FunctionRetTy {
1519     pub fn span(&self) -> Span {
1520         match *self {
1521             NoReturn(span) => span,
1522             DefaultReturn(span) => span,
1523             Return(ref ty) => ty.span
1524         }
1525     }
1526 }
1527
1528 /// Represents the kind of 'self' associated with a method
1529 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1530 pub enum ExplicitSelf_ {
1531     /// No self
1532     SelfStatic,
1533     /// `self`
1534     SelfValue(Ident),
1535     /// `&'lt self`, `&'lt mut self`
1536     SelfRegion(Option<Lifetime>, Mutability, Ident),
1537     /// `self: TYPE`
1538     SelfExplicit(P<Ty>, Ident),
1539 }
1540
1541 pub type ExplicitSelf = Spanned<ExplicitSelf_>;
1542
1543 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1544 pub struct Mod {
1545     /// A span from the first token past `{` to the last token until `}`.
1546     /// For `mod foo;`, the inner span ranges from the first token
1547     /// to the last token in the external file.
1548     pub inner: Span,
1549     pub items: Vec<P<Item>>,
1550 }
1551
1552 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1553 pub struct ForeignMod {
1554     pub abi: Abi,
1555     pub items: Vec<P<ForeignItem>>,
1556 }
1557
1558 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1559 pub struct VariantArg {
1560     pub ty: P<Ty>,
1561     pub id: NodeId,
1562 }
1563
1564 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1565 pub enum VariantKind {
1566     /// Tuple variant, e.g. `Foo(A, B)`
1567     TupleVariantKind(Vec<VariantArg>),
1568     /// Struct variant, e.g. `Foo {x: A, y: B}`
1569     StructVariantKind(P<StructDef>),
1570 }
1571
1572 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1573 pub struct EnumDef {
1574     pub variants: Vec<P<Variant>>,
1575 }
1576
1577 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1578 pub struct Variant_ {
1579     pub name: Ident,
1580     pub attrs: Vec<Attribute>,
1581     pub kind: VariantKind,
1582     pub id: NodeId,
1583     /// Explicit discriminant, eg `Foo = 1`
1584     pub disr_expr: Option<P<Expr>>,
1585     pub vis: Visibility,
1586 }
1587
1588 pub type Variant = Spanned<Variant_>;
1589
1590 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1591 pub enum PathListItem_ {
1592     PathListIdent { name: Ident, id: NodeId },
1593     PathListMod { id: NodeId }
1594 }
1595
1596 impl PathListItem_ {
1597     pub fn id(&self) -> NodeId {
1598         match *self {
1599             PathListIdent { id, .. } | PathListMod { id } => id
1600         }
1601     }
1602 }
1603
1604 pub type PathListItem = Spanned<PathListItem_>;
1605
1606 pub type ViewPath = Spanned<ViewPath_>;
1607
1608 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1609 pub enum ViewPath_ {
1610
1611     /// `foo::bar::baz as quux`
1612     ///
1613     /// or just
1614     ///
1615     /// `foo::bar::baz` (with `as baz` implicitly on the right)
1616     ViewPathSimple(Ident, Path),
1617
1618     /// `foo::bar::*`
1619     ViewPathGlob(Path),
1620
1621     /// `foo::bar::{a,b,c}`
1622     ViewPathList(Path, Vec<PathListItem>)
1623 }
1624
1625 /// Meta-data associated with an item
1626 pub type Attribute = Spanned<Attribute_>;
1627
1628 /// Distinguishes between Attributes that decorate items and Attributes that
1629 /// are contained as statements within items. These two cases need to be
1630 /// distinguished for pretty-printing.
1631 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1632 pub enum AttrStyle {
1633     AttrOuter,
1634     AttrInner,
1635 }
1636
1637 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1638 pub struct AttrId(pub usize);
1639
1640 /// Doc-comments are promoted to attributes that have is_sugared_doc = true
1641 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1642 pub struct Attribute_ {
1643     pub id: AttrId,
1644     pub style: AttrStyle,
1645     pub value: P<MetaItem>,
1646     pub is_sugared_doc: bool,
1647 }
1648
1649 /// TraitRef's appear in impls.
1650 ///
1651 /// resolve maps each TraitRef's ref_id to its defining trait; that's all
1652 /// that the ref_id is for. The impl_id maps to the "self type" of this impl.
1653 /// If this impl is an ItemImpl, the impl_id is redundant (it could be the
1654 /// same as the impl's node id).
1655 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1656 pub struct TraitRef {
1657     pub path: Path,
1658     pub ref_id: NodeId,
1659 }
1660
1661 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1662 pub struct PolyTraitRef {
1663     /// The `'a` in `<'a> Foo<&'a T>`
1664     pub bound_lifetimes: Vec<LifetimeDef>,
1665
1666     /// The `Foo<&'a T>` in `<'a> Foo<&'a T>`
1667     pub trait_ref: TraitRef,
1668
1669     pub span: Span,
1670 }
1671
1672 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1673 pub enum Visibility {
1674     Public,
1675     Inherited,
1676 }
1677
1678 impl Visibility {
1679     pub fn inherit_from(&self, parent_visibility: Visibility) -> Visibility {
1680         match self {
1681             &Inherited => parent_visibility,
1682             &Public => *self
1683         }
1684     }
1685 }
1686
1687 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1688 pub struct StructField_ {
1689     pub kind: StructFieldKind,
1690     pub id: NodeId,
1691     pub ty: P<Ty>,
1692     pub attrs: Vec<Attribute>,
1693 }
1694
1695 impl StructField_ {
1696     pub fn ident(&self) -> Option<Ident> {
1697         match self.kind {
1698             NamedField(ref ident, _) => Some(ident.clone()),
1699             UnnamedField(_) => None
1700         }
1701     }
1702 }
1703
1704 pub type StructField = Spanned<StructField_>;
1705
1706 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1707 pub enum StructFieldKind {
1708     NamedField(Ident, Visibility),
1709     /// Element of a tuple-like struct
1710     UnnamedField(Visibility),
1711 }
1712
1713 impl StructFieldKind {
1714     pub fn is_unnamed(&self) -> bool {
1715         match *self {
1716             UnnamedField(..) => true,
1717             NamedField(..) => false,
1718         }
1719     }
1720 }
1721
1722 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1723 pub struct StructDef {
1724     /// Fields, not including ctor
1725     pub fields: Vec<StructField>,
1726     /// ID of the constructor. This is only used for tuple- or enum-like
1727     /// structs.
1728     pub ctor_id: Option<NodeId>,
1729 }
1730
1731 /*
1732   FIXME (#3300): Should allow items to be anonymous. Right now
1733   we just use dummy names for anon items.
1734  */
1735 /// An item
1736 ///
1737 /// The name might be a dummy name in case of anonymous items
1738 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1739 pub struct Item {
1740     pub ident: Ident,
1741     pub attrs: Vec<Attribute>,
1742     pub id: NodeId,
1743     pub node: Item_,
1744     pub vis: Visibility,
1745     pub span: Span,
1746 }
1747
1748 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1749 pub enum Item_ {
1750     /// An`extern crate` item, with optional original crate name,
1751     ///
1752     /// e.g. `extern crate foo` or `extern crate foo_bar as foo`
1753     ItemExternCrate(Option<Name>),
1754     /// A `use` or `pub use` item
1755     ItemUse(P<ViewPath>),
1756
1757     /// A `static` item
1758     ItemStatic(P<Ty>, Mutability, P<Expr>),
1759     /// A `const` item
1760     ItemConst(P<Ty>, P<Expr>),
1761     /// A function declaration
1762     ItemFn(P<FnDecl>, Unsafety, Abi, Generics, P<Block>),
1763     /// A module
1764     ItemMod(Mod),
1765     /// An external module
1766     ItemForeignMod(ForeignMod),
1767     /// A type alias, e.g. `type Foo = Bar<u8>`
1768     ItemTy(P<Ty>, Generics),
1769     /// An enum definition, e.g. `enum Foo<A, B> {C<A>, D<B>}`
1770     ItemEnum(EnumDef, Generics),
1771     /// A struct definition, e.g. `struct Foo<A> {x: A}`
1772     ItemStruct(P<StructDef>, Generics),
1773     /// Represents a Trait Declaration
1774     ItemTrait(Unsafety,
1775               Generics,
1776               TyParamBounds,
1777               Vec<P<TraitItem>>),
1778
1779     // Default trait implementations
1780     ///
1781     // `impl Trait for .. {}`
1782     ItemDefaultImpl(Unsafety, TraitRef),
1783     /// An implementation, eg `impl<A> Trait for Foo { .. }`
1784     ItemImpl(Unsafety,
1785              ImplPolarity,
1786              Generics,
1787              Option<TraitRef>, // (optional) trait this impl implements
1788              P<Ty>, // self
1789              Vec<P<ImplItem>>),
1790     /// A macro invocation (which includes macro definition)
1791     ItemMac(Mac),
1792 }
1793
1794 impl Item_ {
1795     pub fn descriptive_variant(&self) -> &str {
1796         match *self {
1797             ItemExternCrate(..) => "extern crate",
1798             ItemUse(..) => "use",
1799             ItemStatic(..) => "static item",
1800             ItemConst(..) => "constant item",
1801             ItemFn(..) => "function",
1802             ItemMod(..) => "module",
1803             ItemForeignMod(..) => "foreign module",
1804             ItemTy(..) => "type alias",
1805             ItemEnum(..) => "enum",
1806             ItemStruct(..) => "struct",
1807             ItemTrait(..) => "trait",
1808             ItemMac(..) |
1809             ItemImpl(..) |
1810             ItemDefaultImpl(..) => "item"
1811         }
1812     }
1813 }
1814
1815 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1816 pub struct ForeignItem {
1817     pub ident: Ident,
1818     pub attrs: Vec<Attribute>,
1819     pub node: ForeignItem_,
1820     pub id: NodeId,
1821     pub span: Span,
1822     pub vis: Visibility,
1823 }
1824
1825 /// An item within an `extern` block
1826 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1827 pub enum ForeignItem_ {
1828     /// A foreign function
1829     ForeignItemFn(P<FnDecl>, Generics),
1830     /// A foreign static item (`static ext: u8`), with optional mutability
1831     /// (the boolean is true when mutable)
1832     ForeignItemStatic(P<Ty>, bool),
1833 }
1834
1835 impl ForeignItem_ {
1836     pub fn descriptive_variant(&self) -> &str {
1837         match *self {
1838             ForeignItemFn(..) => "foreign function",
1839             ForeignItemStatic(..) => "foreign static item"
1840         }
1841     }
1842 }
1843
1844 /// The data we save and restore about an inlined item or method.  This is not
1845 /// part of the AST that we parse from a file, but it becomes part of the tree
1846 /// that we trans.
1847 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1848 pub enum InlinedItem {
1849     IIItem(P<Item>),
1850     IITraitItem(DefId /* impl id */, P<TraitItem>),
1851     IIImplItem(DefId /* impl id */, P<ImplItem>),
1852     IIForeign(P<ForeignItem>),
1853 }
1854
1855 /// A macro definition, in this crate or imported from another.
1856 ///
1857 /// Not parsed directly, but created on macro import or `macro_rules!` expansion.
1858 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1859 pub struct MacroDef {
1860     pub ident: Ident,
1861     pub attrs: Vec<Attribute>,
1862     pub id: NodeId,
1863     pub span: Span,
1864     pub imported_from: Option<Ident>,
1865     pub export: bool,
1866     pub use_locally: bool,
1867     pub allow_internal_unstable: bool,
1868     pub body: Vec<TokenTree>,
1869 }
1870
1871 #[cfg(test)]
1872 mod test {
1873     use serialize;
1874     use super::*;
1875
1876     // are ASTs encodable?
1877     #[test]
1878     fn check_asts_encodable() {
1879         fn assert_encodable<T: serialize::Encodable>() {}
1880         assert_encodable::<Crate>();
1881     }
1882 }