src/librustc_front/hir.rs

   1 // Copyright 2015 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 HIR.
  12
  13 pub use self::BindingMode::*;
  14 pub use self::BinOp_::*;
  15 pub use self::BlockCheckMode::*;
  16 pub use self::CaptureClause::*;
  17 pub use self::Decl_::*;
  18 pub use self::ExplicitSelf_::*;
  19 pub use self::Expr_::*;
  20 pub use self::FunctionRetTy::*;
  21 pub use self::ForeignItem_::*;
  22 pub use self::ImplItem_::*;
  23 pub use self::Item_::*;
  24 pub use self::Mutability::*;
  25 pub use self::Pat_::*;
  26 pub use self::PathListItem_::*;
  27 pub use self::PatWildKind::*;
  28 pub use self::PrimTy::*;
  29 pub use self::Stmt_::*;
  30 pub use self::StructFieldKind::*;
  31 pub use self::TraitItem_::*;
  32 pub use self::Ty_::*;
  33 pub use self::TyParamBound::*;
  34 pub use self::UnOp::*;
  35 pub use self::UnsafeSource::*;
  36 pub use self::ViewPath_::*;
  37 pub use self::Visibility::*;
  38 pub use self::PathParameters::*;
  39
  40 use syntax::codemap::{self, Span, Spanned, DUMMY_SP, ExpnId};
  41 use syntax::abi::Abi;
  42 use syntax::ast::{Name, Ident, NodeId, DUMMY_NODE_ID, TokenTree, AsmDialect};
  43 use syntax::ast::{Attribute, Lit, StrStyle, FloatTy, IntTy, UintTy, CrateConfig};
  44 use syntax::owned_slice::OwnedSlice;
  45 use syntax::parse::token::InternedString;
  46 use syntax::ptr::P;
  47
  48 use print::pprust;
  49 use util;
  50
  51 use std::fmt;
  52 use serialize::{Encodable, Encoder, Decoder};
  53
  54 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
  55 pub struct Lifetime {
  56     pub id: NodeId,
  57     pub span: Span,
  58     pub name: Name,
  59 }
  60
  61 impl fmt::Debug for Lifetime {
  62     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  63         write!(f,
  64                "lifetime({}: {})",
  65                self.id,
  66                pprust::lifetime_to_string(self))
  67     }
  68 }
  69
  70 /// A lifetime definition, eg `'a: 'b+'c+'d`
  71 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
  72 pub struct LifetimeDef {
  73     pub lifetime: Lifetime,
  74     pub bounds: Vec<Lifetime>,
  75 }
  76
  77 /// A "Path" is essentially Rust's notion of a name; for instance:
  78 /// std::cmp::PartialEq  .  It's represented as a sequence of identifiers,
  79 /// along with a bunch of supporting information.
  80 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
  81 pub struct Path {
  82     pub span: Span,
  83     /// A `::foo` path, is relative to the crate root rather than current
  84     /// module (like paths in an import).
  85     pub global: bool,
  86     /// The segments in the path: the things separated by `::`.
  87     pub segments: Vec<PathSegment>,
  88 }
  89
  90 impl fmt::Debug for Path {
  91     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  92         write!(f, "path({})", pprust::path_to_string(self))
  93     }
  94 }
  95
  96 impl fmt::Display for Path {
  97     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  98         write!(f, "{}", pprust::path_to_string(self))
  99     }
 100 }
 101
 102 /// A segment of a path: an identifier, an optional lifetime, and a set of
 103 /// types.
 104 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 105 pub struct PathSegment {
 106     /// The identifier portion of this path segment.
 107     pub identifier: Ident,
 108
 109     /// Type/lifetime parameters attached to this path. They come in
 110     /// two flavors: `Path<A,B,C>` and `Path(A,B) -> C`. Note that
 111     /// this is more than just simple syntactic sugar; the use of
 112     /// parens affects the region binding rules, so we preserve the
 113     /// distinction.
 114     pub parameters: PathParameters,
 115 }
 116
 117 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 118 pub enum PathParameters {
 119     /// The `<'a, A,B,C>` in `foo::bar::baz::<'a, A,B,C>`
 120     AngleBracketedParameters(AngleBracketedParameterData),
 121     /// The `(A,B)` and `C` in `Foo(A,B) -> C`
 122     ParenthesizedParameters(ParenthesizedParameterData),
 123 }
 124
 125 impl PathParameters {
 126     pub fn none() -> PathParameters {
 127         AngleBracketedParameters(AngleBracketedParameterData {
 128             lifetimes: Vec::new(),
 129             types: OwnedSlice::empty(),
 130             bindings: OwnedSlice::empty(),
 131         })
 132     }
 133
 134     pub fn is_empty(&self) -> bool {
 135         match *self {
 136             AngleBracketedParameters(ref data) => data.is_empty(),
 137
 138             // Even if the user supplied no types, something like
 139             // `X()` is equivalent to `X<(),()>`.
 140             ParenthesizedParameters(..) => false,
 141         }
 142     }
 143
 144     pub fn has_lifetimes(&self) -> bool {
 145         match *self {
 146             AngleBracketedParameters(ref data) => !data.lifetimes.is_empty(),
 147             ParenthesizedParameters(_) => false,
 148         }
 149     }
 150
 151     pub fn has_types(&self) -> bool {
 152         match *self {
 153             AngleBracketedParameters(ref data) => !data.types.is_empty(),
 154             ParenthesizedParameters(..) => true,
 155         }
 156     }
 157
 158     /// Returns the types that the user wrote. Note that these do not necessarily map to the type
 159     /// parameters in the parenthesized case.
 160     pub fn types(&self) -> Vec<&P<Ty>> {
 161         match *self {
 162             AngleBracketedParameters(ref data) => {
 163                 data.types.iter().collect()
 164             }
 165             ParenthesizedParameters(ref data) => {
 166                 data.inputs
 167                     .iter()
 168                     .chain(data.output.iter())
 169                     .collect()
 170             }
 171         }
 172     }
 173
 174     pub fn lifetimes(&self) -> Vec<&Lifetime> {
 175         match *self {
 176             AngleBracketedParameters(ref data) => {
 177                 data.lifetimes.iter().collect()
 178             }
 179             ParenthesizedParameters(_) => {
 180                 Vec::new()
 181             }
 182         }
 183     }
 184
 185     pub fn bindings(&self) -> Vec<&P<TypeBinding>> {
 186         match *self {
 187             AngleBracketedParameters(ref data) => {
 188                 data.bindings.iter().collect()
 189             }
 190             ParenthesizedParameters(_) => {
 191                 Vec::new()
 192             }
 193         }
 194     }
 195 }
 196
 197 /// A path like `Foo<'a, T>`
 198 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 199 pub struct AngleBracketedParameterData {
 200     /// The lifetime parameters for this path segment.
 201     pub lifetimes: Vec<Lifetime>,
 202     /// The type parameters for this path segment, if present.
 203     pub types: OwnedSlice<P<Ty>>,
 204     /// Bindings (equality constraints) on associated types, if present.
 205     /// E.g., `Foo<A=Bar>`.
 206     pub bindings: OwnedSlice<P<TypeBinding>>,
 207 }
 208
 209 impl AngleBracketedParameterData {
 210     fn is_empty(&self) -> bool {
 211         self.lifetimes.is_empty() && self.types.is_empty() && self.bindings.is_empty()
 212     }
 213 }
 214
 215 /// A path like `Foo(A,B) -> C`
 216 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 217 pub struct ParenthesizedParameterData {
 218     /// Overall span
 219     pub span: Span,
 220
 221     /// `(A,B)`
 222     pub inputs: Vec<P<Ty>>,
 223
 224     /// `C`
 225     pub output: Option<P<Ty>>,
 226 }
 227
 228 /// The AST represents all type param bounds as types.
 229 /// typeck::collect::compute_bounds matches these against
 230 /// the "special" built-in traits (see middle::lang_items) and
 231 /// detects Copy, Send and Sync.
 232 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 233 pub enum TyParamBound {
 234     TraitTyParamBound(PolyTraitRef, TraitBoundModifier),
 235     RegionTyParamBound(Lifetime),
 236 }
 237
 238 /// A modifier on a bound, currently this is only used for `?Sized`, where the
 239 /// modifier is `Maybe`. Negative bounds should also be handled here.
 240 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 241 pub enum TraitBoundModifier {
 242     None,
 243     Maybe,
 244 }
 245
 246 pub type TyParamBounds = OwnedSlice<TyParamBound>;
 247
 248 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 249 pub struct TyParam {
 250     pub name: Name,
 251     pub id: NodeId,
 252     pub bounds: TyParamBounds,
 253     pub default: Option<P<Ty>>,
 254     pub span: Span,
 255 }
 256
 257 /// Represents lifetimes and type parameters attached to a declaration
 258 /// of a function, enum, trait, etc.
 259 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 260 pub struct Generics {
 261     pub lifetimes: Vec<LifetimeDef>,
 262     pub ty_params: OwnedSlice<TyParam>,
 263     pub where_clause: WhereClause,
 264 }
 265
 266 impl Generics {
 267     pub fn is_lt_parameterized(&self) -> bool {
 268         !self.lifetimes.is_empty()
 269     }
 270     pub fn is_type_parameterized(&self) -> bool {
 271         !self.ty_params.is_empty()
 272     }
 273     pub fn is_parameterized(&self) -> bool {
 274         self.is_lt_parameterized() || self.is_type_parameterized()
 275     }
 276 }
 277
 278 /// A `where` clause in a definition
 279 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 280 pub struct WhereClause {
 281     pub id: NodeId,
 282     pub predicates: Vec<WherePredicate>,
 283 }
 284
 285 /// A single predicate in a `where` clause
 286 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 287 pub enum WherePredicate {
 288     /// A type binding, eg `for<'c> Foo: Send+Clone+'c`
 289     BoundPredicate(WhereBoundPredicate),
 290     /// A lifetime predicate, e.g. `'a: 'b+'c`
 291     RegionPredicate(WhereRegionPredicate),
 292     /// An equality predicate (unsupported)
 293     EqPredicate(WhereEqPredicate),
 294 }
 295
 296 /// A type bound, eg `for<'c> Foo: Send+Clone+'c`
 297 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 298 pub struct WhereBoundPredicate {
 299     pub span: Span,
 300     /// Any lifetimes from a `for` binding
 301     pub bound_lifetimes: Vec<LifetimeDef>,
 302     /// The type being bounded
 303     pub bounded_ty: P<Ty>,
 304     /// Trait and lifetime bounds (`Clone+Send+'static`)
 305     pub bounds: OwnedSlice<TyParamBound>,
 306 }
 307
 308 /// A lifetime predicate, e.g. `'a: 'b+'c`
 309 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 310 pub struct WhereRegionPredicate {
 311     pub span: Span,
 312     pub lifetime: Lifetime,
 313     pub bounds: Vec<Lifetime>,
 314 }
 315
 316 /// An equality predicate (unsupported), e.g. `T=int`
 317 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 318 pub struct WhereEqPredicate {
 319     pub id: NodeId,
 320     pub span: Span,
 321     pub path: Path,
 322     pub ty: P<Ty>,
 323 }
 324
 325 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 326 pub struct Crate {
 327     pub module: Mod,
 328     pub attrs: Vec<Attribute>,
 329     pub config: CrateConfig,
 330     pub span: Span,
 331     pub exported_macros: Vec<MacroDef>,
 332 }
 333
 334 /// A macro definition, in this crate or imported from another.
 335 ///
 336 /// Not parsed directly, but created on macro import or `macro_rules!` expansion.
 337 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 338 pub struct MacroDef {
 339     pub name: Name,
 340     pub attrs: Vec<Attribute>,
 341     pub id: NodeId,
 342     pub span: Span,
 343     pub imported_from: Option<Name>,
 344     pub export: bool,
 345     pub use_locally: bool,
 346     pub allow_internal_unstable: bool,
 347     pub body: Vec<TokenTree>,
 348 }
 349
 350 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 351 pub struct Block {
 352     /// Statements in a block
 353     pub stmts: Vec<P<Stmt>>,
 354     /// An expression at the end of the block
 355     /// without a semicolon, if any
 356     pub expr: Option<P<Expr>>,
 357     pub id: NodeId,
 358     /// Distinguishes between `unsafe { ... }` and `{ ... }`
 359     pub rules: BlockCheckMode,
 360     pub span: Span,
 361 }
 362
 363 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
 364 pub struct Pat {
 365     pub id: NodeId,
 366     pub node: Pat_,
 367     pub span: Span,
 368 }
 369
 370 impl fmt::Debug for Pat {
 371     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 372         write!(f, "pat({}: {})", self.id, pprust::pat_to_string(self))
 373     }
 374 }
 375
 376 /// A single field in a struct pattern
 377 ///
 378 /// Patterns like the fields of Foo `{ x, ref y, ref mut z }`
 379 /// are treated the same as` x: x, y: ref y, z: ref mut z`,
 380 /// except is_shorthand is true
 381 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 382 pub struct FieldPat {
 383     /// The identifier for the field
 384     pub name: Name,
 385     /// The pattern the field is destructured to
 386     pub pat: P<Pat>,
 387     pub is_shorthand: bool,
 388 }
 389
 390 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 391 pub enum BindingMode {
 392     BindByRef(Mutability),
 393     BindByValue(Mutability),
 394 }
 395
 396 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 397 pub enum PatWildKind {
 398     /// Represents the wildcard pattern `_`
 399     PatWildSingle,
 400
 401     /// Represents the wildcard pattern `..`
 402     PatWildMulti,
 403 }
 404
 405 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 406 pub enum Pat_ {
 407     /// Represents a wildcard pattern (either `_` or `..`)
 408     PatWild(PatWildKind),
 409
 410     /// A PatIdent may either be a new bound variable,
 411     /// or a nullary enum (in which case the third field
 412     /// is None).
 413     ///
 414     /// In the nullary enum case, the parser can't determine
 415     /// which it is. The resolver determines this, and
 416     /// records this pattern's NodeId in an auxiliary
 417     /// set (of "PatIdents that refer to nullary enums")
 418     PatIdent(BindingMode, Spanned<Ident>, Option<P<Pat>>),
 419
 420     /// "None" means a * pattern where we don't bind the fields to names.
 421     PatEnum(Path, Option<Vec<P<Pat>>>),
 422
 423     /// An associated const named using the qualified path `<T>::CONST` or
 424     /// `<T as Trait>::CONST`. Associated consts from inherent impls can be
 425     /// referred to as simply `T::CONST`, in which case they will end up as
 426     /// PatEnum, and the resolver will have to sort that out.
 427     PatQPath(QSelf, Path),
 428
 429     /// Destructuring of a struct, e.g. `Foo {x, y, ..}`
 430     /// The `bool` is `true` in the presence of a `..`
 431     PatStruct(Path, Vec<Spanned<FieldPat>>, bool),
 432     /// A tuple pattern `(a, b)`
 433     PatTup(Vec<P<Pat>>),
 434     /// A `box` pattern
 435     PatBox(P<Pat>),
 436     /// A reference pattern, e.g. `&mut (a, b)`
 437     PatRegion(P<Pat>, Mutability),
 438     /// A literal
 439     PatLit(P<Expr>),
 440     /// A range pattern, e.g. `1...2`
 441     PatRange(P<Expr>, P<Expr>),
 442     /// [a, b, ..i, y, z] is represented as:
 443     ///     PatVec(box [a, b], Some(i), box [y, z])
 444     PatVec(Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>),
 445 }
 446
 447 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 448 pub enum Mutability {
 449     MutMutable,
 450     MutImmutable,
 451 }
 452
 453 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 454 pub enum BinOp_ {
 455     /// The `+` operator (addition)
 456     BiAdd,
 457     /// The `-` operator (subtraction)
 458     BiSub,
 459     /// The `*` operator (multiplication)
 460     BiMul,
 461     /// The `/` operator (division)
 462     BiDiv,
 463     /// The `%` operator (modulus)
 464     BiRem,
 465     /// The `&&` operator (logical and)
 466     BiAnd,
 467     /// The `||` operator (logical or)
 468     BiOr,
 469     /// The `^` operator (bitwise xor)
 470     BiBitXor,
 471     /// The `&` operator (bitwise and)
 472     BiBitAnd,
 473     /// The `|` operator (bitwise or)
 474     BiBitOr,
 475     /// The `<<` operator (shift left)
 476     BiShl,
 477     /// The `>>` operator (shift right)
 478     BiShr,
 479     /// The `==` operator (equality)
 480     BiEq,
 481     /// The `<` operator (less than)
 482     BiLt,
 483     /// The `<=` operator (less than or equal to)
 484     BiLe,
 485     /// The `!=` operator (not equal to)
 486     BiNe,
 487     /// The `>=` operator (greater than or equal to)
 488     BiGe,
 489     /// The `>` operator (greater than)
 490     BiGt,
 491 }
 492
 493 pub type BinOp = Spanned<BinOp_>;
 494
 495 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 496 pub enum UnOp {
 497     /// The `*` operator for dereferencing
 498     UnDeref,
 499     /// The `!` operator for logical inversion
 500     UnNot,
 501     /// The `-` operator for negation
 502     UnNeg,
 503 }
 504
 505 /// A statement
 506 pub type Stmt = Spanned<Stmt_>;
 507
 508 impl fmt::Debug for Stmt_ {
 509     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 510         // Sadness.
 511         let spanned = codemap::dummy_spanned(self.clone());
 512         write!(f,
 513                "stmt({}: {})",
 514                util::stmt_id(&spanned),
 515                pprust::stmt_to_string(&spanned))
 516     }
 517 }
 518
 519 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
 520 pub enum Stmt_ {
 521     /// Could be an item or a local (let) binding:
 522     StmtDecl(P<Decl>, NodeId),
 523
 524     /// Expr without trailing semi-colon (must have unit type):
 525     StmtExpr(P<Expr>, NodeId),
 526
 527     /// Expr with trailing semi-colon (may have any type):
 528     StmtSemi(P<Expr>, NodeId),
 529 }
 530
 531 // FIXME (pending discussion of #1697, #2178...): local should really be
 532 // a refinement on pat.
 533 /// Local represents a `let` statement, e.g., `let <pat>:<ty> = <expr>;`
 534 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 535 pub struct Local {
 536     pub pat: P<Pat>,
 537     pub ty: Option<P<Ty>>,
 538     /// Initializer expression to set the value, if any
 539     pub init: Option<P<Expr>>,
 540     pub id: NodeId,
 541     pub span: Span,
 542 }
 543
 544 pub type Decl = Spanned<Decl_>;
 545
 546 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 547 pub enum Decl_ {
 548     /// A local (let) binding:
 549     DeclLocal(P<Local>),
 550     /// An item binding:
 551     DeclItem(P<Item>),
 552 }
 553
 554 /// represents one arm of a 'match'
 555 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 556 pub struct Arm {
 557     pub attrs: Vec<Attribute>,
 558     pub pats: Vec<P<Pat>>,
 559     pub guard: Option<P<Expr>>,
 560     pub body: P<Expr>,
 561 }
 562
 563 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 564 pub struct Field {
 565     pub name: Spanned<Name>,
 566     pub expr: P<Expr>,
 567     pub span: Span,
 568 }
 569
 570 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 571 pub enum BlockCheckMode {
 572     DefaultBlock,
 573     UnsafeBlock(UnsafeSource),
 574     PushUnsafeBlock(UnsafeSource),
 575     PopUnsafeBlock(UnsafeSource),
 576     // Within this block (but outside a PopUnstableBlock), we suspend checking of stability.
 577     PushUnstableBlock,
 578     PopUnstableBlock,
 579 }
 580
 581 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 582 pub enum UnsafeSource {
 583     CompilerGenerated,
 584     UserProvided,
 585 }
 586
 587 /// An expression
 588 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
 589 pub struct Expr {
 590     pub id: NodeId,
 591     pub node: Expr_,
 592     pub span: Span,
 593 }
 594
 595 impl fmt::Debug for Expr {
 596     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 597         write!(f, "expr({}: {})", self.id, pprust::expr_to_string(self))
 598     }
 599 }
 600
 601 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 602 pub enum Expr_ {
 603     /// A `box x` expression.
 604     ExprBox(P<Expr>),
 605     /// An array (`[a, b, c, d]`)
 606     ExprVec(Vec<P<Expr>>),
 607     /// A function call
 608     ///
 609     /// The first field resolves to the function itself,
 610     /// and the second field is the list of arguments
 611     ExprCall(P<Expr>, Vec<P<Expr>>),
 612     /// A method call (`x.foo::<Bar, Baz>(a, b, c, d)`)
 613     ///
 614     /// The `Spanned<Name>` is the identifier for the method name.
 615     /// The vector of `Ty`s are the ascripted type parameters for the method
 616     /// (within the angle brackets).
 617     ///
 618     /// The first element of the vector of `Expr`s is the expression that evaluates
 619     /// to the object on which the method is being called on (the receiver),
 620     /// and the remaining elements are the rest of the arguments.
 621     ///
 622     /// Thus, `x.foo::<Bar, Baz>(a, b, c, d)` is represented as
 623     /// `ExprMethodCall(foo, [Bar, Baz], [x, a, b, c, d])`.
 624     ExprMethodCall(Spanned<Name>, Vec<P<Ty>>, Vec<P<Expr>>),
 625     /// A tuple (`(a, b, c ,d)`)
 626     ExprTup(Vec<P<Expr>>),
 627     /// A binary operation (For example: `a + b`, `a * b`)
 628     ExprBinary(BinOp, P<Expr>, P<Expr>),
 629     /// A unary operation (For example: `!x`, `*x`)
 630     ExprUnary(UnOp, P<Expr>),
 631     /// A literal (For example: `1u8`, `"foo"`)
 632     ExprLit(P<Lit>),
 633     /// A cast (`foo as f64`)
 634     ExprCast(P<Expr>, P<Ty>),
 635     /// An `if` block, with an optional else block
 636     ///
 637     /// `if expr { block } else { expr }`
 638     ExprIf(P<Expr>, P<Block>, Option<P<Expr>>),
 639     /// A while loop, with an optional label
 640     ///
 641     /// `'label: while expr { block }`
 642     ExprWhile(P<Expr>, P<Block>, Option<Ident>),
 643     /// Conditionless loop (can be exited with break, continue, or return)
 644     ///
 645     /// `'label: loop { block }`
 646     ExprLoop(P<Block>, Option<Ident>),
 647     /// A `match` block, with a source that indicates whether or not it is
 648     /// the result of a desugaring, and if so, which kind.
 649     ExprMatch(P<Expr>, Vec<Arm>, MatchSource),
 650     /// A closure (for example, `move |a, b, c| {a + b + c}`)
 651     ExprClosure(CaptureClause, P<FnDecl>, P<Block>),
 652     /// A block (`{ ... }`)
 653     ExprBlock(P<Block>),
 654
 655     /// An assignment (`a = foo()`)
 656     ExprAssign(P<Expr>, P<Expr>),
 657     /// An assignment with an operator
 658     ///
 659     /// For example, `a += 1`.
 660     ExprAssignOp(BinOp, P<Expr>, P<Expr>),
 661     /// Access of a named struct field (`obj.foo`)
 662     ExprField(P<Expr>, Spanned<Name>),
 663     /// Access of an unnamed field of a struct or tuple-struct
 664     ///
 665     /// For example, `foo.0`.
 666     ExprTupField(P<Expr>, Spanned<usize>),
 667     /// An indexing operation (`foo[2]`)
 668     ExprIndex(P<Expr>, P<Expr>),
 669     /// A range (`1..2`, `1..`, or `..2`)
 670     ExprRange(Option<P<Expr>>, Option<P<Expr>>),
 671
 672     /// Variable reference, possibly containing `::` and/or type
 673     /// parameters, e.g. foo::bar::<baz>.
 674     ///
 675     /// Optionally "qualified",
 676     /// e.g. `<Vec<T> as SomeTrait>::SomeType`.
 677     ExprPath(Option<QSelf>, Path),
 678
 679     /// A referencing operation (`&a` or `&mut a`)
 680     ExprAddrOf(Mutability, P<Expr>),
 681     /// A `break`, with an optional label to break
 682     ExprBreak(Option<Spanned<Ident>>),
 683     /// A `continue`, with an optional label
 684     ExprAgain(Option<Spanned<Ident>>),
 685     /// A `return`, with an optional value to be returned
 686     ExprRet(Option<P<Expr>>),
 687
 688     /// Output of the `asm!()` macro
 689     ExprInlineAsm(InlineAsm),
 690
 691     /// A struct literal expression.
 692     ///
 693     /// For example, `Foo {x: 1, y: 2}`, or
 694     /// `Foo {x: 1, .. base}`, where `base` is the `Option<Expr>`.
 695     ExprStruct(Path, Vec<Field>, Option<P<Expr>>),
 696
 697     /// A vector literal constructed from one repeated element.
 698     ///
 699     /// For example, `[1u8; 5]`. The first expression is the element
 700     /// to be repeated; the second is the number of times to repeat it.
 701     ExprRepeat(P<Expr>, P<Expr>),
 702 }
 703
 704 /// The explicit Self type in a "qualified path". The actual
 705 /// path, including the trait and the associated item, is stored
 706 /// separately. `position` represents the index of the associated
 707 /// item qualified with this Self type.
 708 ///
 709 ///     <Vec<T> as a::b::Trait>::AssociatedItem
 710 ///      ^~~~~     ~~~~~~~~~~~~~~^
 711 ///      ty        position = 3
 712 ///
 713 ///     <Vec<T>>::AssociatedItem
 714 ///      ^~~~~    ^
 715 ///      ty       position = 0
 716 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 717 pub struct QSelf {
 718     pub ty: P<Ty>,
 719     pub position: usize,
 720 }
 721
 722 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 723 pub enum MatchSource {
 724     Normal,
 725     IfLetDesugar {
 726         contains_else_clause: bool,
 727     },
 728     WhileLetDesugar,
 729     ForLoopDesugar,
 730 }
 731
 732 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 733 pub enum CaptureClause {
 734     CaptureByValue,
 735     CaptureByRef,
 736 }
 737
 738 // NB: If you change this, you'll probably want to change the corresponding
 739 // type structure in middle/ty.rs as well.
 740 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 741 pub struct MutTy {
 742     pub ty: P<Ty>,
 743     pub mutbl: Mutability,
 744 }
 745
 746 /// Represents a method's signature in a trait declaration,
 747 /// or in an implementation.
 748 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 749 pub struct MethodSig {
 750     pub unsafety: Unsafety,
 751     pub constness: Constness,
 752     pub abi: Abi,
 753     pub decl: P<FnDecl>,
 754     pub generics: Generics,
 755     pub explicit_self: ExplicitSelf,
 756 }
 757
 758 /// Represents a method declaration in a trait declaration, possibly including
 759 /// a default implementation A trait method is either required (meaning it
 760 /// doesn't have an implementation, just a signature) or provided (meaning it
 761 /// has a default implementation).
 762 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 763 pub struct TraitItem {
 764     pub id: NodeId,
 765     pub name: Name,
 766     pub attrs: Vec<Attribute>,
 767     pub node: TraitItem_,
 768     pub span: Span,
 769 }
 770
 771 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 772 pub enum TraitItem_ {
 773     ConstTraitItem(P<Ty>, Option<P<Expr>>),
 774     MethodTraitItem(MethodSig, Option<P<Block>>),
 775     TypeTraitItem(TyParamBounds, Option<P<Ty>>),
 776 }
 777
 778 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 779 pub struct ImplItem {
 780     pub id: NodeId,
 781     pub name: Name,
 782     pub vis: Visibility,
 783     pub attrs: Vec<Attribute>,
 784     pub node: ImplItem_,
 785     pub span: Span,
 786 }
 787
 788 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 789 pub enum ImplItem_ {
 790     ConstImplItem(P<Ty>, P<Expr>),
 791     MethodImplItem(MethodSig, P<Block>),
 792     TypeImplItem(P<Ty>),
 793 }
 794
 795 // Bind a type to an associated type: `A=Foo`.
 796 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 797 pub struct TypeBinding {
 798     pub id: NodeId,
 799     pub name: Name,
 800     pub ty: P<Ty>,
 801     pub span: Span,
 802 }
 803
 804
 805 // NB PartialEq method appears below.
 806 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
 807 pub struct Ty {
 808     pub id: NodeId,
 809     pub node: Ty_,
 810     pub span: Span,
 811 }
 812
 813 impl fmt::Debug for Ty {
 814     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 815         write!(f, "type({})", pprust::ty_to_string(self))
 816     }
 817 }
 818
 819 /// Not represented directly in the AST, referred to by name through a ty_path.
 820 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 821 pub enum PrimTy {
 822     TyInt(IntTy),
 823     TyUint(UintTy),
 824     TyFloat(FloatTy),
 825     TyStr,
 826     TyBool,
 827     TyChar,
 828 }
 829
 830 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 831 pub struct BareFnTy {
 832     pub unsafety: Unsafety,
 833     pub abi: Abi,
 834     pub lifetimes: Vec<LifetimeDef>,
 835     pub decl: P<FnDecl>,
 836 }
 837
 838 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 839 /// The different kinds of types recognized by the compiler
 840 pub enum Ty_ {
 841     TyVec(P<Ty>),
 842     /// A fixed length array (`[T; n]`)
 843     TyFixedLengthVec(P<Ty>, P<Expr>),
 844     /// A raw pointer (`*const T` or `*mut T`)
 845     TyPtr(MutTy),
 846     /// A reference (`&'a T` or `&'a mut T`)
 847     TyRptr(Option<Lifetime>, MutTy),
 848     /// A bare function (e.g. `fn(usize) -> bool`)
 849     TyBareFn(P<BareFnTy>),
 850     /// A tuple (`(A, B, C, D,...)`)
 851     TyTup(Vec<P<Ty>>),
 852     /// A path (`module::module::...::Type`), optionally
 853     /// "qualified", e.g. `<Vec<T> as SomeTrait>::SomeType`.
 854     ///
 855     /// Type parameters are stored in the Path itself
 856     TyPath(Option<QSelf>, Path),
 857     /// Something like `A+B`. Note that `B` must always be a path.
 858     TyObjectSum(P<Ty>, TyParamBounds),
 859     /// A type like `for<'a> Foo<&'a Bar>`
 860     TyPolyTraitRef(TyParamBounds),
 861     /// No-op; kept solely so that we can pretty-print faithfully
 862     TyParen(P<Ty>),
 863     /// Unused for now
 864     TyTypeof(P<Expr>),
 865     /// TyInfer means the type should be inferred instead of it having been
 866     /// specified. This can appear anywhere in a type.
 867     TyInfer,
 868 }
 869
 870 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 871 pub struct InlineAsm {
 872     pub asm: InternedString,
 873     pub asm_str_style: StrStyle,
 874     pub outputs: Vec<(InternedString, P<Expr>, bool)>,
 875     pub inputs: Vec<(InternedString, P<Expr>)>,
 876     pub clobbers: Vec<InternedString>,
 877     pub volatile: bool,
 878     pub alignstack: bool,
 879     pub dialect: AsmDialect,
 880     pub expn_id: ExpnId,
 881 }
 882
 883 /// represents an argument in a function header
 884 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 885 pub struct Arg {
 886     pub ty: P<Ty>,
 887     pub pat: P<Pat>,
 888     pub id: NodeId,
 889 }
 890
 891 impl Arg {
 892     pub fn new_self(span: Span, mutability: Mutability, self_ident: Ident) -> Arg {
 893         let path = Spanned {
 894             span: span,
 895             node: self_ident,
 896         };
 897         Arg {
 898             // HACK(eddyb) fake type for the self argument.
 899             ty: P(Ty {
 900                 id: DUMMY_NODE_ID,
 901                 node: TyInfer,
 902                 span: DUMMY_SP,
 903             }),
 904             pat: P(Pat {
 905                 id: DUMMY_NODE_ID,
 906                 node: PatIdent(BindByValue(mutability), path, None),
 907                 span: span,
 908             }),
 909             id: DUMMY_NODE_ID,
 910         }
 911     }
 912 }
 913
 914 /// Represents the header (not the body) of a function declaration
 915 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 916 pub struct FnDecl {
 917     pub inputs: Vec<Arg>,
 918     pub output: FunctionRetTy,
 919     pub variadic: bool,
 920 }
 921
 922 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 923 pub enum Unsafety {
 924     Unsafe,
 925     Normal,
 926 }
 927
 928 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 929 pub enum Constness {
 930     Const,
 931     NotConst,
 932 }
 933
 934 impl fmt::Display for Unsafety {
 935     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 936         fmt::Display::fmt(match *self {
 937                               Unsafety::Normal => "normal",
 938                               Unsafety::Unsafe => "unsafe",
 939                           },
 940                           f)
 941     }
 942 }
 943
 944 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
 945 pub enum ImplPolarity {
 946     /// `impl Trait for Type`
 947     Positive,
 948     /// `impl !Trait for Type`
 949     Negative,
 950 }
 951
 952 impl fmt::Debug for ImplPolarity {
 953     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 954         match *self {
 955             ImplPolarity::Positive => "positive".fmt(f),
 956             ImplPolarity::Negative => "negative".fmt(f),
 957         }
 958     }
 959 }
 960
 961
 962 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 963 pub enum FunctionRetTy {
 964     /// Functions with return type `!`that always
 965     /// raise an error or exit (i.e. never return to the caller)
 966     NoReturn(Span),
 967     /// Return type is not specified.
 968     ///
 969     /// Functions default to `()` and
 970     /// closures default to inference. Span points to where return
 971     /// type would be inserted.
 972     DefaultReturn(Span),
 973     /// Everything else
 974     Return(P<Ty>),
 975 }
 976
 977 impl FunctionRetTy {
 978     pub fn span(&self) -> Span {
 979         match *self {
 980             NoReturn(span) => span,
 981             DefaultReturn(span) => span,
 982             Return(ref ty) => ty.span,
 983         }
 984     }
 985 }
 986
 987 /// Represents the kind of 'self' associated with a method
 988 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 989 pub enum ExplicitSelf_ {
 990     /// No self
 991     SelfStatic,
 992     /// `self`
 993     SelfValue(Name),
 994     /// `&'lt self`, `&'lt mut self`
 995     SelfRegion(Option<Lifetime>, Mutability, Name),
 996     /// `self: TYPE`
 997     SelfExplicit(P<Ty>, Name),
 998 }
 999
1000 pub type ExplicitSelf = Spanned<ExplicitSelf_>;
1001
1002 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1003 pub struct Mod {
1004     /// A span from the first token past `{` to the last token until `}`.
1005     /// For `mod foo;`, the inner span ranges from the first token
1006     /// to the last token in the external file.
1007     pub inner: Span,
1008     pub items: Vec<P<Item>>,
1009 }
1010
1011 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1012 pub struct ForeignMod {
1013     pub abi: Abi,
1014     pub items: Vec<P<ForeignItem>>,
1015 }
1016
1017 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1018 pub struct EnumDef {
1019     pub variants: Vec<P<Variant>>,
1020 }
1021
1022 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1023 pub struct Variant_ {
1024     pub name: Name,
1025     pub attrs: Vec<Attribute>,
1026     pub data: VariantData,
1027     /// Explicit discriminant, eg `Foo = 1`
1028     pub disr_expr: Option<P<Expr>>,
1029 }
1030
1031 pub type Variant = Spanned<Variant_>;
1032
1033 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1034 pub enum PathListItem_ {
1035     PathListIdent {
1036         name: Name,
1037         /// renamed in list, eg `use foo::{bar as baz};`
1038         rename: Option<Name>,
1039         id: NodeId,
1040     },
1041     PathListMod {
1042         /// renamed in list, eg `use foo::{self as baz};`
1043         rename: Option<Name>,
1044         id: NodeId,
1045     },
1046 }
1047
1048 impl PathListItem_ {
1049     pub fn id(&self) -> NodeId {
1050         match *self {
1051             PathListIdent { id, .. } | PathListMod { id, .. } => id,
1052         }
1053     }
1054
1055     pub fn name(&self) -> Option<Name> {
1056         match *self {
1057             PathListIdent { name, .. } => Some(name),
1058             PathListMod { .. } => None,
1059         }
1060     }
1061
1062     pub fn rename(&self) -> Option<Name> {
1063         match *self {
1064             PathListIdent { rename, .. } | PathListMod { rename, .. } => rename,
1065         }
1066     }
1067 }
1068
1069 pub type PathListItem = Spanned<PathListItem_>;
1070
1071 pub type ViewPath = Spanned<ViewPath_>;
1072
1073 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1074 pub enum ViewPath_ {
1075
1076     /// `foo::bar::baz as quux`
1077     ///
1078     /// or just
1079     ///
1080     /// `foo::bar::baz` (with `as baz` implicitly on the right)
1081     ViewPathSimple(Name, Path),
1082
1083     /// `foo::bar::*`
1084     ViewPathGlob(Path),
1085
1086     /// `foo::bar::{a,b,c}`
1087     ViewPathList(Path, Vec<PathListItem>),
1088 }
1089
1090 /// TraitRef's appear in impls.
1091 ///
1092 /// resolve maps each TraitRef's ref_id to its defining trait; that's all
1093 /// that the ref_id is for. The impl_id maps to the "self type" of this impl.
1094 /// If this impl is an ItemImpl, the impl_id is redundant (it could be the
1095 /// same as the impl's node id).
1096 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1097 pub struct TraitRef {
1098     pub path: Path,
1099     pub ref_id: NodeId,
1100 }
1101
1102 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1103 pub struct PolyTraitRef {
1104     /// The `'a` in `<'a> Foo<&'a T>`
1105     pub bound_lifetimes: Vec<LifetimeDef>,
1106
1107     /// The `Foo<&'a T>` in `<'a> Foo<&'a T>`
1108     pub trait_ref: TraitRef,
1109
1110     pub span: Span,
1111 }
1112
1113 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1114 pub enum Visibility {
1115     Public,
1116     Inherited,
1117 }
1118
1119 impl Visibility {
1120     pub fn inherit_from(&self, parent_visibility: Visibility) -> Visibility {
1121         match self {
1122             &Inherited => parent_visibility,
1123             &Public => *self,
1124         }
1125     }
1126 }
1127
1128 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1129 pub struct StructField_ {
1130     pub kind: StructFieldKind,
1131     pub id: NodeId,
1132     pub ty: P<Ty>,
1133     pub attrs: Vec<Attribute>,
1134 }
1135
1136 impl StructField_ {
1137     pub fn name(&self) -> Option<Name> {
1138         match self.kind {
1139             NamedField(name, _) => Some(name),
1140             UnnamedField(_) => None,
1141         }
1142     }
1143 }
1144
1145 pub type StructField = Spanned<StructField_>;
1146
1147 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1148 pub enum StructFieldKind {
1149     NamedField(Name, Visibility),
1150     /// Element of a tuple-like struct
1151     UnnamedField(Visibility),
1152 }
1153
1154 impl StructFieldKind {
1155     pub fn is_unnamed(&self) -> bool {
1156         match *self {
1157             UnnamedField(..) => true,
1158             NamedField(..) => false,
1159         }
1160     }
1161 }
1162
1163 /// Fields and Ids of enum variants and structs
1164 ///
1165 /// For enum variants: `NodeId` represents both an Id of the variant itself (relevant for all
1166 /// variant kinds) and an Id of the variant's constructor (not relevant for `Struct`-variants).
1167 /// One shared Id can be successfully used for these two purposes.
1168 /// Id of the whole enum lives in `Item`.
1169 ///
1170 /// For structs: `NodeId` represents an Id of the structure's constructor, so it is not actually
1171 /// used for `Struct`-structs (but still presents). Structures don't have an analogue of "Id of
1172 /// the variant itself" from enum variants.
1173 /// Id of the whole struct lives in `Item`.
1174 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1175 pub enum VariantData {
1176     Struct(Vec<StructField>, NodeId),
1177     Tuple(Vec<StructField>, NodeId),
1178     Unit(NodeId),
1179 }
1180
1181 impl VariantData {
1182     pub fn fields(&self) -> &[StructField] {
1183         match *self {
1184             VariantData::Struct(ref fields, _) | VariantData::Tuple(ref fields, _) => fields,
1185             _ => &[],
1186         }
1187     }
1188     pub fn id(&self) -> NodeId {
1189         match *self {
1190             VariantData::Struct(_, id) | VariantData::Tuple(_, id) | VariantData::Unit(id) => id
1191         }
1192     }
1193     pub fn is_struct(&self) -> bool {
1194         if let VariantData::Struct(..) = *self { true } else { false }
1195     }
1196     pub fn is_tuple(&self) -> bool {
1197         if let VariantData::Tuple(..) = *self { true } else { false }
1198     }
1199     pub fn is_unit(&self) -> bool {
1200         if let VariantData::Unit(..) = *self { true } else { false }
1201     }
1202 }
1203
1204 /*
1205   FIXME (#3300): Should allow items to be anonymous. Right now
1206   we just use dummy names for anon items.
1207  */
1208 /// An item
1209 ///
1210 /// The name might be a dummy name in case of anonymous items
1211 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1212 pub struct Item {
1213     pub name: Name,
1214     pub attrs: Vec<Attribute>,
1215     pub id: NodeId,
1216     pub node: Item_,
1217     pub vis: Visibility,
1218     pub span: Span,
1219 }
1220
1221 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1222 pub enum Item_ {
1223     /// An`extern crate` item, with optional original crate name,
1224     ///
1225     /// e.g. `extern crate foo` or `extern crate foo_bar as foo`
1226     ItemExternCrate(Option<Name>),
1227     /// A `use` or `pub use` item
1228     ItemUse(P<ViewPath>),
1229
1230     /// A `static` item
1231     ItemStatic(P<Ty>, Mutability, P<Expr>),
1232     /// A `const` item
1233     ItemConst(P<Ty>, P<Expr>),
1234     /// A function declaration
1235     ItemFn(P<FnDecl>, Unsafety, Constness, Abi, Generics, P<Block>),
1236     /// A module
1237     ItemMod(Mod),
1238     /// An external module
1239     ItemForeignMod(ForeignMod),
1240     /// A type alias, e.g. `type Foo = Bar<u8>`
1241     ItemTy(P<Ty>, Generics),
1242     /// An enum definition, e.g. `enum Foo<A, B> {C<A>, D<B>}`
1243     ItemEnum(EnumDef, Generics),
1244     /// A struct definition, e.g. `struct Foo<A> {x: A}`
1245     ItemStruct(VariantData, Generics),
1246     /// Represents a Trait Declaration
1247     ItemTrait(Unsafety, Generics, TyParamBounds, Vec<P<TraitItem>>),
1248
1249     // Default trait implementations
1250     ///
1251     // `impl Trait for .. {}`
1252     ItemDefaultImpl(Unsafety, TraitRef),
1253     /// An implementation, eg `impl<A> Trait for Foo { .. }`
1254     ItemImpl(Unsafety,
1255              ImplPolarity,
1256              Generics,
1257              Option<TraitRef>, // (optional) trait this impl implements
1258              P<Ty>, // self
1259              Vec<P<ImplItem>>),
1260 }
1261
1262 impl Item_ {
1263     pub fn descriptive_variant(&self) -> &str {
1264         match *self {
1265             ItemExternCrate(..) => "extern crate",
1266             ItemUse(..) => "use",
1267             ItemStatic(..) => "static item",
1268             ItemConst(..) => "constant item",
1269             ItemFn(..) => "function",
1270             ItemMod(..) => "module",
1271             ItemForeignMod(..) => "foreign module",
1272             ItemTy(..) => "type alias",
1273             ItemEnum(..) => "enum",
1274             ItemStruct(..) => "struct",
1275             ItemTrait(..) => "trait",
1276             ItemImpl(..) |
1277             ItemDefaultImpl(..) => "item",
1278         }
1279     }
1280 }
1281
1282 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1283 pub struct ForeignItem {
1284     pub name: Name,
1285     pub attrs: Vec<Attribute>,
1286     pub node: ForeignItem_,
1287     pub id: NodeId,
1288     pub span: Span,
1289     pub vis: Visibility,
1290 }
1291
1292 /// An item within an `extern` block
1293 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1294 pub enum ForeignItem_ {
1295     /// A foreign function
1296     ForeignItemFn(P<FnDecl>, Generics),
1297     /// A foreign static item (`static ext: u8`), with optional mutability
1298     /// (the boolean is true when mutable)
1299     ForeignItemStatic(P<Ty>, bool),
1300 }
1301
1302 impl ForeignItem_ {
1303     pub fn descriptive_variant(&self) -> &str {
1304         match *self {
1305             ForeignItemFn(..) => "foreign function",
1306             ForeignItemStatic(..) => "foreign static item",
1307         }
1308     }
1309 }