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::TyParamBound::*;
  14 pub use self::UnsafeSource::*;
  15 pub use self::ViewPath_::*;
  16 pub use self::PathParameters::*;
  17
  18 use attr::ThinAttributes;
  19 use codemap::{Span, Spanned, DUMMY_SP, ExpnId};
  20 use abi::Abi;
  21 use errors;
  22 use ext::base;
  23 use ext::tt::macro_parser;
  24 use parse::token::InternedString;
  25 use parse::token;
  26 use parse::lexer;
  27 use parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
  28 use print::pprust;
  29 use ptr::P;
  30
  31 use std::fmt;
  32 use std::rc::Rc;
  33 use std::borrow::Cow;
  34 use std::hash::{Hash, Hasher};
  35 use serialize::{Encodable, Decodable, Encoder, Decoder};
  36
  37 /// A name is a part of an identifier, representing a string or gensym. It's
  38 /// the result of interning.
  39 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
  40 pub struct Name(pub u32);
  41
  42 /// A SyntaxContext represents a chain of macro-expandings
  43 /// and renamings. Each macro expansion corresponds to
  44 /// a fresh u32. This u32 is a reference to a table stored
  45 /// in thread-local storage.
  46 /// The special value EMPTY_CTXT is used to indicate an empty
  47 /// syntax context.
  48 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
  49 pub struct SyntaxContext(pub u32);
  50
  51 /// An identifier contains a Name (index into the interner
  52 /// table) and a SyntaxContext to track renaming and
  53 /// macro expansion per Flatt et al., "Macros That Work Together"
  54 #[derive(Clone, Copy, Eq)]
  55 pub struct Ident {
  56     pub name: Name,
  57     pub ctxt: SyntaxContext
  58 }
  59
  60 impl Name {
  61     pub fn as_str(self) -> token::InternedString {
  62         token::InternedString::new_from_name(self)
  63     }
  64 }
  65
  66 impl fmt::Debug for Name {
  67     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  68         write!(f, "{}({})", self, self.0)
  69     }
  70 }
  71
  72 impl fmt::Display for Name {
  73     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  74         fmt::Display::fmt(&self.as_str(), f)
  75     }
  76 }
  77
  78 impl Encodable for Name {
  79     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
  80         s.emit_str(&self.as_str())
  81     }
  82 }
  83
  84 impl Decodable for Name {
  85     fn decode<D: Decoder>(d: &mut D) -> Result<Name, D::Error> {
  86         Ok(token::intern(&d.read_str()?[..]))
  87     }
  88 }
  89
  90 pub const EMPTY_CTXT : SyntaxContext = SyntaxContext(0);
  91
  92 impl Ident {
  93     pub fn new(name: Name, ctxt: SyntaxContext) -> Ident {
  94         Ident {name: name, ctxt: ctxt}
  95     }
  96     pub fn with_empty_ctxt(name: Name) -> Ident {
  97         Ident {name: name, ctxt: EMPTY_CTXT}
  98     }
  99 }
 100
 101 impl PartialEq for Ident {
 102     fn eq(&self, other: &Ident) -> bool {
 103         if self.ctxt != other.ctxt {
 104             // There's no one true way to compare Idents. They can be compared
 105             // non-hygienically `id1.name == id2.name`, hygienically
 106             // `mtwt::resolve(id1) == mtwt::resolve(id2)`, or even member-wise
 107             // `(id1.name, id1.ctxt) == (id2.name, id2.ctxt)` depending on the situation.
 108             // Ideally, PartialEq should not be implemented for Ident at all, but that
 109             // would be too impractical, because many larger structures (Token, in particular)
 110             // including Idents as their parts derive PartialEq and use it for non-hygienic
 111             // comparisons. That's why PartialEq is implemented and defaults to non-hygienic
 112             // comparison. Hash is implemented too and is consistent with PartialEq, i.e. only
 113             // the name of Ident is hashed. Still try to avoid comparing idents in your code
 114             // (especially as keys in hash maps), use one of the three methods listed above
 115             // explicitly.
 116             //
 117             // If you see this panic, then some idents from different contexts were compared
 118             // non-hygienically. It's likely a bug. Use one of the three comparison methods
 119             // listed above explicitly.
 120
 121             panic!("idents with different contexts are compared with operator `==`: \
 122                 {:?}, {:?}.", self, other);
 123         }
 124
 125         self.name == other.name
 126     }
 127 }
 128
 129 impl Hash for Ident {
 130     fn hash<H: Hasher>(&self, state: &mut H) {
 131         self.name.hash(state)
 132     }
 133 }
 134
 135 impl fmt::Debug for Ident {
 136     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 137         write!(f, "{}#{}", self.name, self.ctxt.0)
 138     }
 139 }
 140
 141 impl fmt::Display for Ident {
 142     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 143         fmt::Display::fmt(&self.name, f)
 144     }
 145 }
 146
 147 impl Encodable for Ident {
 148     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
 149         self.name.encode(s)
 150     }
 151 }
 152
 153 impl Decodable for Ident {
 154     fn decode<D: Decoder>(d: &mut D) -> Result<Ident, D::Error> {
 155         Ok(Ident::with_empty_ctxt(Name::decode(d)?))
 156     }
 157 }
 158
 159 /// A mark represents a unique id associated with a macro expansion
 160 pub type Mrk = u32;
 161
 162 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
 163 pub struct Lifetime {
 164     pub id: NodeId,
 165     pub span: Span,
 166     pub name: Name
 167 }
 168
 169 impl fmt::Debug for Lifetime {
 170     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 171         write!(f, "lifetime({}: {})", self.id, pprust::lifetime_to_string(self))
 172     }
 173 }
 174
 175 /// A lifetime definition, eg `'a: 'b+'c+'d`
 176 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 177 pub struct LifetimeDef {
 178     pub lifetime: Lifetime,
 179     pub bounds: Vec<Lifetime>
 180 }
 181
 182 /// A "Path" is essentially Rust's notion of a name; for instance:
 183 /// std::cmp::PartialEq  .  It's represented as a sequence of identifiers,
 184 /// along with a bunch of supporting information.
 185 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
 186 pub struct Path {
 187     pub span: Span,
 188     /// A `::foo` path, is relative to the crate root rather than current
 189     /// module (like paths in an import).
 190     pub global: bool,
 191     /// The segments in the path: the things separated by `::`.
 192     pub segments: Vec<PathSegment>,
 193 }
 194
 195 impl fmt::Debug for Path {
 196     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 197         write!(f, "path({})", pprust::path_to_string(self))
 198     }
 199 }
 200
 201 impl fmt::Display for Path {
 202     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 203         write!(f, "{}", pprust::path_to_string(self))
 204     }
 205 }
 206
 207 impl Path {
 208     // convert a span and an identifier to the corresponding
 209     // 1-segment path
 210     pub fn from_ident(s: Span, identifier: Ident) -> Path {
 211         Path {
 212             span: s,
 213             global: false,
 214             segments: vec!(
 215                 PathSegment {
 216                     identifier: identifier,
 217                     parameters: PathParameters::none()
 218                 }
 219             ),
 220         }
 221     }
 222 }
 223
 224 /// A segment of a path: an identifier, an optional lifetime, and a set of
 225 /// types.
 226 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 227 pub struct PathSegment {
 228     /// The identifier portion of this path segment.
 229     pub identifier: Ident,
 230
 231     /// Type/lifetime parameters attached to this path. They come in
 232     /// two flavors: `Path<A,B,C>` and `Path(A,B) -> C`. Note that
 233     /// this is more than just simple syntactic sugar; the use of
 234     /// parens affects the region binding rules, so we preserve the
 235     /// distinction.
 236     pub parameters: PathParameters,
 237 }
 238
 239 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 240 pub enum PathParameters {
 241     /// The `<'a, A,B,C>` in `foo::bar::baz::<'a, A,B,C>`
 242     AngleBracketed(AngleBracketedParameterData),
 243     /// The `(A,B)` and `C` in `Foo(A,B) -> C`
 244     Parenthesized(ParenthesizedParameterData),
 245 }
 246
 247 impl PathParameters {
 248     pub fn none() -> PathParameters {
 249         PathParameters::AngleBracketed(AngleBracketedParameterData {
 250             lifetimes: Vec::new(),
 251             types: P::empty(),
 252             bindings: P::empty(),
 253         })
 254     }
 255
 256     pub fn is_empty(&self) -> bool {
 257         match *self {
 258             PathParameters::AngleBracketed(ref data) => data.is_empty(),
 259
 260             // Even if the user supplied no types, something like
 261             // `X()` is equivalent to `X<(),()>`.
 262             PathParameters::Parenthesized(..) => false,
 263         }
 264     }
 265
 266     pub fn has_lifetimes(&self) -> bool {
 267         match *self {
 268             PathParameters::AngleBracketed(ref data) => !data.lifetimes.is_empty(),
 269             PathParameters::Parenthesized(_) => false,
 270         }
 271     }
 272
 273     pub fn has_types(&self) -> bool {
 274         match *self {
 275             PathParameters::AngleBracketed(ref data) => !data.types.is_empty(),
 276             PathParameters::Parenthesized(..) => true,
 277         }
 278     }
 279
 280     /// Returns the types that the user wrote. Note that these do not necessarily map to the type
 281     /// parameters in the parenthesized case.
 282     pub fn types(&self) -> Vec<&P<Ty>> {
 283         match *self {
 284             PathParameters::AngleBracketed(ref data) => {
 285                 data.types.iter().collect()
 286             }
 287             PathParameters::Parenthesized(ref data) => {
 288                 data.inputs.iter()
 289                     .chain(data.output.iter())
 290                     .collect()
 291             }
 292         }
 293     }
 294
 295     pub fn lifetimes(&self) -> Vec<&Lifetime> {
 296         match *self {
 297             PathParameters::AngleBracketed(ref data) => {
 298                 data.lifetimes.iter().collect()
 299             }
 300             PathParameters::Parenthesized(_) => {
 301                 Vec::new()
 302             }
 303         }
 304     }
 305
 306     pub fn bindings(&self) -> Vec<&TypeBinding> {
 307         match *self {
 308             PathParameters::AngleBracketed(ref data) => {
 309                 data.bindings.iter().collect()
 310             }
 311             PathParameters::Parenthesized(_) => {
 312                 Vec::new()
 313             }
 314         }
 315     }
 316 }
 317
 318 /// A path like `Foo<'a, T>`
 319 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 320 pub struct AngleBracketedParameterData {
 321     /// The lifetime parameters for this path segment.
 322     pub lifetimes: Vec<Lifetime>,
 323     /// The type parameters for this path segment, if present.
 324     pub types: P<[P<Ty>]>,
 325     /// Bindings (equality constraints) on associated types, if present.
 326     /// e.g., `Foo<A=Bar>`.
 327     pub bindings: P<[TypeBinding]>,
 328 }
 329
 330 impl AngleBracketedParameterData {
 331     fn is_empty(&self) -> bool {
 332         self.lifetimes.is_empty() && self.types.is_empty() && self.bindings.is_empty()
 333     }
 334 }
 335
 336 /// A path like `Foo(A,B) -> C`
 337 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 338 pub struct ParenthesizedParameterData {
 339     /// Overall span
 340     pub span: Span,
 341
 342     /// `(A,B)`
 343     pub inputs: Vec<P<Ty>>,
 344
 345     /// `C`
 346     pub output: Option<P<Ty>>,
 347 }
 348
 349 pub type CrateNum = u32;
 350
 351 pub type NodeId = u32;
 352
 353 /// Node id used to represent the root of the crate.
 354 pub const CRATE_NODE_ID: NodeId = 0;
 355
 356 /// When parsing and doing expansions, we initially give all AST nodes this AST
 357 /// node value. Then later, in the renumber pass, we renumber them to have
 358 /// small, positive ids.
 359 pub const DUMMY_NODE_ID: NodeId = !0;
 360
 361 pub trait NodeIdAssigner {
 362     fn next_node_id(&self) -> NodeId;
 363     fn peek_node_id(&self) -> NodeId;
 364
 365     fn diagnostic(&self) -> &errors::Handler {
 366         panic!("this ID assigner cannot emit diagnostics")
 367     }
 368 }
 369
 370 /// The AST represents all type param bounds as types.
 371 /// typeck::collect::compute_bounds matches these against
 372 /// the "special" built-in traits (see middle::lang_items) and
 373 /// detects Copy, Send and Sync.
 374 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 375 pub enum TyParamBound {
 376     TraitTyParamBound(PolyTraitRef, TraitBoundModifier),
 377     RegionTyParamBound(Lifetime)
 378 }
 379
 380 /// A modifier on a bound, currently this is only used for `?Sized`, where the
 381 /// modifier is `Maybe`. Negative bounds should also be handled here.
 382 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 383 pub enum TraitBoundModifier {
 384     None,
 385     Maybe,
 386 }
 387
 388 pub type TyParamBounds = P<[TyParamBound]>;
 389
 390 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 391 pub struct TyParam {
 392     pub ident: Ident,
 393     pub id: NodeId,
 394     pub bounds: TyParamBounds,
 395     pub default: Option<P<Ty>>,
 396     pub span: Span
 397 }
 398
 399 /// Represents lifetimes and type parameters attached to a declaration
 400 /// of a function, enum, trait, etc.
 401 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 402 pub struct Generics {
 403     pub lifetimes: Vec<LifetimeDef>,
 404     pub ty_params: P<[TyParam]>,
 405     pub where_clause: WhereClause,
 406 }
 407
 408 impl Generics {
 409     pub fn is_lt_parameterized(&self) -> bool {
 410         !self.lifetimes.is_empty()
 411     }
 412     pub fn is_type_parameterized(&self) -> bool {
 413         !self.ty_params.is_empty()
 414     }
 415     pub fn is_parameterized(&self) -> bool {
 416         self.is_lt_parameterized() || self.is_type_parameterized()
 417     }
 418 }
 419
 420 impl Default for Generics {
 421     fn default() ->  Generics {
 422         Generics {
 423             lifetimes: Vec::new(),
 424             ty_params: P::empty(),
 425             where_clause: WhereClause {
 426                 id: DUMMY_NODE_ID,
 427                 predicates: Vec::new(),
 428             }
 429         }
 430     }
 431 }
 432
 433 /// A `where` clause in a definition
 434 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 435 pub struct WhereClause {
 436     pub id: NodeId,
 437     pub predicates: Vec<WherePredicate>,
 438 }
 439
 440 /// A single predicate in a `where` clause
 441 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 442 pub enum WherePredicate {
 443     /// A type binding, e.g. `for<'c> Foo: Send+Clone+'c`
 444     BoundPredicate(WhereBoundPredicate),
 445     /// A lifetime predicate, e.g. `'a: 'b+'c`
 446     RegionPredicate(WhereRegionPredicate),
 447     /// An equality predicate (unsupported)
 448     EqPredicate(WhereEqPredicate),
 449 }
 450
 451 /// A type bound, e.g. `for<'c> Foo: Send+Clone+'c`
 452 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 453 pub struct WhereBoundPredicate {
 454     pub span: Span,
 455     /// Any lifetimes from a `for` binding
 456     pub bound_lifetimes: Vec<LifetimeDef>,
 457     /// The type being bounded
 458     pub bounded_ty: P<Ty>,
 459     /// Trait and lifetime bounds (`Clone+Send+'static`)
 460     pub bounds: TyParamBounds,
 461 }
 462
 463 /// A lifetime predicate, e.g. `'a: 'b+'c`
 464 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 465 pub struct WhereRegionPredicate {
 466     pub span: Span,
 467     pub lifetime: Lifetime,
 468     pub bounds: Vec<Lifetime>,
 469 }
 470
 471 /// An equality predicate (unsupported), e.g. `T=int`
 472 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 473 pub struct WhereEqPredicate {
 474     pub id: NodeId,
 475     pub span: Span,
 476     pub path: Path,
 477     pub ty: P<Ty>,
 478 }
 479
 480 /// The set of MetaItems that define the compilation environment of the crate,
 481 /// used to drive conditional compilation
 482 pub type CrateConfig = Vec<P<MetaItem>>;
 483
 484 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 485 pub struct Crate {
 486     pub module: Mod,
 487     pub attrs: Vec<Attribute>,
 488     pub config: CrateConfig,
 489     pub span: Span,
 490     pub exported_macros: Vec<MacroDef>,
 491 }
 492
 493 pub type MetaItem = Spanned<MetaItemKind>;
 494
 495 #[derive(Clone, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 496 pub enum MetaItemKind {
 497     Word(InternedString),
 498     List(InternedString, Vec<P<MetaItem>>),
 499     NameValue(InternedString, Lit),
 500 }
 501
 502 // can't be derived because the MetaItemKind::List requires an unordered comparison
 503 impl PartialEq for MetaItemKind {
 504     fn eq(&self, other: &MetaItemKind) -> bool {
 505         use self::MetaItemKind::*;
 506         match *self {
 507             Word(ref ns) => match *other {
 508                 Word(ref no) => (*ns) == (*no),
 509                 _ => false
 510             },
 511             NameValue(ref ns, ref vs) => match *other {
 512                 NameValue(ref no, ref vo) => {
 513                     (*ns) == (*no) && vs.node == vo.node
 514                 }
 515                 _ => false
 516             },
 517             List(ref ns, ref miss) => match *other {
 518                 List(ref no, ref miso) => {
 519                     ns == no &&
 520                         miss.iter().all(|mi| miso.iter().any(|x| x.node == mi.node))
 521                 }
 522                 _ => false
 523             }
 524         }
 525     }
 526 }
 527
 528 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 529 pub struct Block {
 530     /// Statements in a block
 531     pub stmts: Vec<Stmt>,
 532     /// An expression at the end of the block
 533     /// without a semicolon, if any
 534     pub expr: Option<P<Expr>>,
 535     pub id: NodeId,
 536     /// Distinguishes between `unsafe { ... }` and `{ ... }`
 537     pub rules: BlockCheckMode,
 538     pub span: Span,
 539 }
 540
 541 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
 542 pub struct Pat {
 543     pub id: NodeId,
 544     pub node: PatKind,
 545     pub span: Span,
 546 }
 547
 548 impl fmt::Debug for Pat {
 549     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 550         write!(f, "pat({}: {})", self.id, pprust::pat_to_string(self))
 551     }
 552 }
 553
 554 /// A single field in a struct pattern
 555 ///
 556 /// Patterns like the fields of Foo `{ x, ref y, ref mut z }`
 557 /// are treated the same as` x: x, y: ref y, z: ref mut z`,
 558 /// except is_shorthand is true
 559 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 560 pub struct FieldPat {
 561     /// The identifier for the field
 562     pub ident: Ident,
 563     /// The pattern the field is destructured to
 564     pub pat: P<Pat>,
 565     pub is_shorthand: bool,
 566 }
 567
 568 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 569 pub enum BindingMode {
 570     ByRef(Mutability),
 571     ByValue(Mutability),
 572 }
 573
 574 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 575 pub enum PatKind {
 576     /// Represents a wildcard pattern (`_`)
 577     Wild,
 578
 579     /// A `PatKind::Ident` may either be a new bound variable,
 580     /// or a unit struct/variant pattern, or a const pattern (in the last two cases
 581     /// the third field must be `None`).
 582     ///
 583     /// In the unit or const pattern case, the parser can't determine
 584     /// which it is. The resolver determines this, and
 585     /// records this pattern's `NodeId` in an auxiliary
 586     /// set (of "PatIdents that refer to unit patterns or constants").
 587     Ident(BindingMode, SpannedIdent, Option<P<Pat>>),
 588
 589     /// A struct or struct variant pattern, e.g. `Variant {x, y, ..}`.
 590     /// The `bool` is `true` in the presence of a `..`.
 591     Struct(Path, Vec<Spanned<FieldPat>>, bool),
 592
 593     /// A tuple struct/variant pattern `Variant(x, y, z)`.
 594     /// "None" means a `Variant(..)` pattern where we don't bind the fields to names.
 595     TupleStruct(Path, Option<Vec<P<Pat>>>),
 596
 597     /// A path pattern.
 598     /// Such pattern can be resolved to a unit struct/variant or a constant.
 599     Path(Path),
 600
 601     /// An associated const named using the qualified path `<T>::CONST` or
 602     /// `<T as Trait>::CONST`. Associated consts from inherent impls can be
 603     /// referred to as simply `T::CONST`, in which case they will end up as
 604     /// PatKind::Path, and the resolver will have to sort that out.
 605     QPath(QSelf, Path),
 606
 607     /// A tuple pattern `(a, b)`
 608     Tup(Vec<P<Pat>>),
 609     /// A `box` pattern
 610     Box(P<Pat>),
 611     /// A reference pattern, e.g. `&mut (a, b)`
 612     Ref(P<Pat>, Mutability),
 613     /// A literal
 614     Lit(P<Expr>),
 615     /// A range pattern, e.g. `1...2`
 616     Range(P<Expr>, P<Expr>),
 617     /// `[a, b, ..i, y, z]` is represented as:
 618     ///     `PatKind::Vec(box [a, b], Some(i), box [y, z])`
 619     Vec(Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>),
 620     /// A macro pattern; pre-expansion
 621     Mac(Mac),
 622 }
 623
 624 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 625 pub enum Mutability {
 626     Mutable,
 627     Immutable,
 628 }
 629
 630 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 631 pub enum BinOpKind {
 632     /// The `+` operator (addition)
 633     Add,
 634     /// The `-` operator (subtraction)
 635     Sub,
 636     /// The `*` operator (multiplication)
 637     Mul,
 638     /// The `/` operator (division)
 639     Div,
 640     /// The `%` operator (modulus)
 641     Rem,
 642     /// The `&&` operator (logical and)
 643     And,
 644     /// The `||` operator (logical or)
 645     Or,
 646     /// The `^` operator (bitwise xor)
 647     BitXor,
 648     /// The `&` operator (bitwise and)
 649     BitAnd,
 650     /// The `|` operator (bitwise or)
 651     BitOr,
 652     /// The `<<` operator (shift left)
 653     Shl,
 654     /// The `>>` operator (shift right)
 655     Shr,
 656     /// The `==` operator (equality)
 657     Eq,
 658     /// The `<` operator (less than)
 659     Lt,
 660     /// The `<=` operator (less than or equal to)
 661     Le,
 662     /// The `!=` operator (not equal to)
 663     Ne,
 664     /// The `>=` operator (greater than or equal to)
 665     Ge,
 666     /// The `>` operator (greater than)
 667     Gt,
 668 }
 669
 670 impl BinOpKind {
 671     pub fn to_string(&self) -> &'static str {
 672         use self::BinOpKind::*;
 673         match *self {
 674             Add => "+",
 675             Sub => "-",
 676             Mul => "*",
 677             Div => "/",
 678             Rem => "%",
 679             And => "&&",
 680             Or => "||",
 681             BitXor => "^",
 682             BitAnd => "&",
 683             BitOr => "|",
 684             Shl => "<<",
 685             Shr => ">>",
 686             Eq => "==",
 687             Lt => "<",
 688             Le => "<=",
 689             Ne => "!=",
 690             Ge => ">=",
 691             Gt => ">",
 692         }
 693     }
 694     pub fn lazy(&self) -> bool {
 695         match *self {
 696             BinOpKind::And | BinOpKind::Or => true,
 697             _ => false
 698         }
 699     }
 700
 701     pub fn is_shift(&self) -> bool {
 702         match *self {
 703             BinOpKind::Shl | BinOpKind::Shr => true,
 704             _ => false
 705         }
 706     }
 707     pub fn is_comparison(&self) -> bool {
 708         use self::BinOpKind::*;
 709         match *self {
 710             Eq | Lt | Le | Ne | Gt | Ge =>
 711             true,
 712             And | Or | Add | Sub | Mul | Div | Rem |
 713             BitXor | BitAnd | BitOr | Shl | Shr =>
 714             false,
 715         }
 716     }
 717     /// Returns `true` if the binary operator takes its arguments by value
 718     pub fn is_by_value(&self) -> bool {
 719         !self.is_comparison()
 720     }
 721 }
 722
 723 pub type BinOp = Spanned<BinOpKind>;
 724
 725 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 726 pub enum UnOp {
 727     /// The `*` operator for dereferencing
 728     Deref,
 729     /// The `!` operator for logical inversion
 730     Not,
 731     /// The `-` operator for negation
 732     Neg,
 733 }
 734
 735 impl UnOp {
 736     /// Returns `true` if the unary operator takes its argument by value
 737     pub fn is_by_value(u: UnOp) -> bool {
 738         match u {
 739             UnOp::Neg | UnOp::Not => true,
 740             _ => false,
 741         }
 742     }
 743
 744     pub fn to_string(op: UnOp) -> &'static str {
 745         match op {
 746             UnOp::Deref => "*",
 747             UnOp::Not => "!",
 748             UnOp::Neg => "-",
 749         }
 750     }
 751 }
 752
 753 /// A statement
 754 pub type Stmt = Spanned<StmtKind>;
 755
 756 impl fmt::Debug for Stmt {
 757     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 758         write!(f, "stmt({}: {})",
 759                self.node.id()
 760                    .map_or(Cow::Borrowed("<macro>"),|id|Cow::Owned(id.to_string())),
 761                pprust::stmt_to_string(self))
 762     }
 763 }
 764
 765
 766 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
 767 pub enum StmtKind {
 768     /// Could be an item or a local (let) binding:
 769     Decl(P<Decl>, NodeId),
 770
 771     /// Expr without trailing semi-colon (must have unit type):
 772     Expr(P<Expr>, NodeId),
 773
 774     /// Expr with trailing semi-colon (may have any type):
 775     Semi(P<Expr>, NodeId),
 776
 777     Mac(P<Mac>, MacStmtStyle, ThinAttributes),
 778 }
 779
 780 impl StmtKind {
 781     pub fn id(&self) -> Option<NodeId> {
 782         match *self {
 783             StmtKind::Decl(_, id) => Some(id),
 784             StmtKind::Expr(_, id) => Some(id),
 785             StmtKind::Semi(_, id) => Some(id),
 786             StmtKind::Mac(..) => None,
 787         }
 788     }
 789
 790     pub fn attrs(&self) -> &[Attribute] {
 791         match *self {
 792             StmtKind::Decl(ref d, _) => d.attrs(),
 793             StmtKind::Expr(ref e, _) |
 794             StmtKind::Semi(ref e, _) => e.attrs(),
 795             StmtKind::Mac(_, _, Some(ref b)) => b,
 796             StmtKind::Mac(_, _, None) => &[],
 797         }
 798     }
 799 }
 800
 801 #[derive(Clone, Copy, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 802 pub enum MacStmtStyle {
 803     /// The macro statement had a trailing semicolon, e.g. `foo! { ... };`
 804     /// `foo!(...);`, `foo![...];`
 805     Semicolon,
 806     /// The macro statement had braces; e.g. foo! { ... }
 807     Braces,
 808     /// The macro statement had parentheses or brackets and no semicolon; e.g.
 809     /// `foo!(...)`. All of these will end up being converted into macro
 810     /// expressions.
 811     NoBraces,
 812 }
 813
 814 // FIXME (pending discussion of #1697, #2178...): local should really be
 815 // a refinement on pat.
 816 /// Local represents a `let` statement, e.g., `let <pat>:<ty> = <expr>;`
 817 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 818 pub struct Local {
 819     pub pat: P<Pat>,
 820     pub ty: Option<P<Ty>>,
 821     /// Initializer expression to set the value, if any
 822     pub init: Option<P<Expr>>,
 823     pub id: NodeId,
 824     pub span: Span,
 825     pub attrs: ThinAttributes,
 826 }
 827
 828 impl Local {
 829     pub fn attrs(&self) -> &[Attribute] {
 830         match self.attrs {
 831             Some(ref b) => b,
 832             None => &[],
 833         }
 834     }
 835 }
 836
 837 pub type Decl = Spanned<DeclKind>;
 838
 839 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 840 pub enum DeclKind {
 841     /// A local (let) binding:
 842     Local(P<Local>),
 843     /// An item binding:
 844     Item(P<Item>),
 845 }
 846
 847 impl Decl {
 848     pub fn attrs(&self) -> &[Attribute] {
 849         match self.node {
 850             DeclKind::Local(ref l) => l.attrs(),
 851             DeclKind::Item(ref i) => i.attrs(),
 852         }
 853     }
 854 }
 855
 856 /// represents one arm of a 'match'
 857 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 858 pub struct Arm {
 859     pub attrs: Vec<Attribute>,
 860     pub pats: Vec<P<Pat>>,
 861     pub guard: Option<P<Expr>>,
 862     pub body: P<Expr>,
 863 }
 864
 865 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 866 pub struct Field {
 867     pub ident: SpannedIdent,
 868     pub expr: P<Expr>,
 869     pub span: Span,
 870 }
 871
 872 pub type SpannedIdent = Spanned<Ident>;
 873
 874 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 875 pub enum BlockCheckMode {
 876     Default,
 877     Unsafe(UnsafeSource),
 878 }
 879
 880 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 881 pub enum UnsafeSource {
 882     CompilerGenerated,
 883     UserProvided,
 884 }
 885
 886 /// An expression
 887 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash,)]
 888 pub struct Expr {
 889     pub id: NodeId,
 890     pub node: ExprKind,
 891     pub span: Span,
 892     pub attrs: ThinAttributes
 893 }
 894
 895 impl Expr {
 896     pub fn attrs(&self) -> &[Attribute] {
 897         match self.attrs {
 898             Some(ref b) => b,
 899             None => &[],
 900         }
 901     }
 902 }
 903
 904 impl fmt::Debug for Expr {
 905     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 906         write!(f, "expr({}: {})", self.id, pprust::expr_to_string(self))
 907     }
 908 }
 909
 910 /// Limit types of a range (inclusive or exclusive)
 911 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 912 pub enum RangeLimits {
 913     /// Inclusive at the beginning, exclusive at the end
 914     HalfOpen,
 915     /// Inclusive at the beginning and end
 916     Closed,
 917 }
 918
 919 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 920 pub enum ExprKind {
 921     /// A `box x` expression.
 922     Box(P<Expr>),
 923     /// First expr is the place; second expr is the value.
 924     InPlace(P<Expr>, P<Expr>),
 925     /// An array (`[a, b, c, d]`)
 926     Vec(Vec<P<Expr>>),
 927     /// A function call
 928     ///
 929     /// The first field resolves to the function itself,
 930     /// and the second field is the list of arguments
 931     Call(P<Expr>, Vec<P<Expr>>),
 932     /// A method call (`x.foo::<Bar, Baz>(a, b, c, d)`)
 933     ///
 934     /// The `SpannedIdent` is the identifier for the method name.
 935     /// The vector of `Ty`s are the ascripted type parameters for the method
 936     /// (within the angle brackets).
 937     ///
 938     /// The first element of the vector of `Expr`s is the expression that evaluates
 939     /// to the object on which the method is being called on (the receiver),
 940     /// and the remaining elements are the rest of the arguments.
 941     ///
 942     /// Thus, `x.foo::<Bar, Baz>(a, b, c, d)` is represented as
 943     /// `ExprKind::MethodCall(foo, [Bar, Baz], [x, a, b, c, d])`.
 944     MethodCall(SpannedIdent, Vec<P<Ty>>, Vec<P<Expr>>),
 945     /// A tuple (`(a, b, c ,d)`)
 946     Tup(Vec<P<Expr>>),
 947     /// A binary operation (For example: `a + b`, `a * b`)
 948     Binary(BinOp, P<Expr>, P<Expr>),
 949     /// A unary operation (For example: `!x`, `*x`)
 950     Unary(UnOp, P<Expr>),
 951     /// A literal (For example: `1`, `"foo"`)
 952     Lit(P<Lit>),
 953     /// A cast (`foo as f64`)
 954     Cast(P<Expr>, P<Ty>),
 955     Type(P<Expr>, P<Ty>),
 956     /// An `if` block, with an optional else block
 957     ///
 958     /// `if expr { block } else { expr }`
 959     If(P<Expr>, P<Block>, Option<P<Expr>>),
 960     /// An `if let` expression with an optional else block
 961     ///
 962     /// `if let pat = expr { block } else { expr }`
 963     ///
 964     /// This is desugared to a `match` expression.
 965     IfLet(P<Pat>, P<Expr>, P<Block>, Option<P<Expr>>),
 966     /// A while loop, with an optional label
 967     ///
 968     /// `'label: while expr { block }`
 969     While(P<Expr>, P<Block>, Option<Ident>),
 970     /// A while-let loop, with an optional label
 971     ///
 972     /// `'label: while let pat = expr { block }`
 973     ///
 974     /// This is desugared to a combination of `loop` and `match` expressions.
 975     WhileLet(P<Pat>, P<Expr>, P<Block>, Option<Ident>),
 976     /// A for loop, with an optional label
 977     ///
 978     /// `'label: for pat in expr { block }`
 979     ///
 980     /// This is desugared to a combination of `loop` and `match` expressions.
 981     ForLoop(P<Pat>, P<Expr>, P<Block>, Option<Ident>),
 982     /// Conditionless loop (can be exited with break, continue, or return)
 983     ///
 984     /// `'label: loop { block }`
 985     Loop(P<Block>, Option<Ident>),
 986     /// A `match` block.
 987     Match(P<Expr>, Vec<Arm>),
 988     /// A closure (for example, `move |a, b, c| {a + b + c}`)
 989     Closure(CaptureBy, P<FnDecl>, P<Block>),
 990     /// A block (`{ ... }`)
 991     Block(P<Block>),
 992
 993     /// An assignment (`a = foo()`)
 994     Assign(P<Expr>, P<Expr>),
 995     /// An assignment with an operator
 996     ///
 997     /// For example, `a += 1`.
 998     AssignOp(BinOp, P<Expr>, P<Expr>),
 999     /// Access of a named struct field (`obj.foo`)
1000     Field(P<Expr>, SpannedIdent),
1001     /// Access of an unnamed field of a struct or tuple-struct
1002     ///
1003     /// For example, `foo.0`.
1004     TupField(P<Expr>, Spanned<usize>),
1005     /// An indexing operation (`foo[2]`)
1006     Index(P<Expr>, P<Expr>),
1007     /// A range (`1..2`, `1..`, `..2`, `1...2`, `1...`, `...2`)
1008     Range(Option<P<Expr>>, Option<P<Expr>>, RangeLimits),
1009
1010     /// Variable reference, possibly containing `::` and/or type
1011     /// parameters, e.g. foo::bar::<baz>.
1012     ///
1013     /// Optionally "qualified",
1014     /// e.g. `<Vec<T> as SomeTrait>::SomeType`.
1015     Path(Option<QSelf>, Path),
1016
1017     /// A referencing operation (`&a` or `&mut a`)
1018     AddrOf(Mutability, P<Expr>),
1019     /// A `break`, with an optional label to break
1020     Break(Option<SpannedIdent>),
1021     /// A `continue`, with an optional label
1022     Again(Option<SpannedIdent>),
1023     /// A `return`, with an optional value to be returned
1024     Ret(Option<P<Expr>>),
1025
1026     /// Output of the `asm!()` macro
1027     InlineAsm(InlineAsm),
1028
1029     /// A macro invocation; pre-expansion
1030     Mac(Mac),
1031
1032     /// A struct literal expression.
1033     ///
1034     /// For example, `Foo {x: 1, y: 2}`, or
1035     /// `Foo {x: 1, .. base}`, where `base` is the `Option<Expr>`.
1036     Struct(Path, Vec<Field>, Option<P<Expr>>),
1037
1038     /// An array literal constructed from one repeated element.
1039     ///
1040     /// For example, `[1; 5]`. The first expression is the element
1041     /// to be repeated; the second is the number of times to repeat it.
1042     Repeat(P<Expr>, P<Expr>),
1043
1044     /// No-op: used solely so we can pretty-print faithfully
1045     Paren(P<Expr>),
1046
1047     /// `expr?`
1048     Try(P<Expr>),
1049 }
1050
1051 /// The explicit Self type in a "qualified path". The actual
1052 /// path, including the trait and the associated item, is stored
1053 /// separately. `position` represents the index of the associated
1054 /// item qualified with this Self type.
1055 ///
1056 /// ```ignore
1057 /// <Vec<T> as a::b::Trait>::AssociatedItem
1058 ///  ^~~~~     ~~~~~~~~~~~~~~^
1059 ///  ty        position = 3
1060 ///
1061 /// <Vec<T>>::AssociatedItem
1062 ///  ^~~~~    ^
1063 ///  ty       position = 0
1064 /// ```
1065 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1066 pub struct QSelf {
1067     pub ty: P<Ty>,
1068     pub position: usize
1069 }
1070
1071 /// A capture clause
1072 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1073 pub enum CaptureBy {
1074     Value,
1075     Ref,
1076 }
1077
1078 /// A delimited sequence of token trees
1079 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1080 pub struct Delimited {
1081     /// The type of delimiter
1082     pub delim: token::DelimToken,
1083     /// The span covering the opening delimiter
1084     pub open_span: Span,
1085     /// The delimited sequence of token trees
1086     pub tts: Vec<TokenTree>,
1087     /// The span covering the closing delimiter
1088     pub close_span: Span,
1089 }
1090
1091 impl Delimited {
1092     /// Returns the opening delimiter as a token.
1093     pub fn open_token(&self) -> token::Token {
1094         token::OpenDelim(self.delim)
1095     }
1096
1097     /// Returns the closing delimiter as a token.
1098     pub fn close_token(&self) -> token::Token {
1099         token::CloseDelim(self.delim)
1100     }
1101
1102     /// Returns the opening delimiter as a token tree.
1103     pub fn open_tt(&self) -> TokenTree {
1104         TokenTree::Token(self.open_span, self.open_token())
1105     }
1106
1107     /// Returns the closing delimiter as a token tree.
1108     pub fn close_tt(&self) -> TokenTree {
1109         TokenTree::Token(self.close_span, self.close_token())
1110     }
1111 }
1112
1113 /// A sequence of token trees
1114 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1115 pub struct SequenceRepetition {
1116     /// The sequence of token trees
1117     pub tts: Vec<TokenTree>,
1118     /// The optional separator
1119     pub separator: Option<token::Token>,
1120     /// Whether the sequence can be repeated zero (*), or one or more times (+)
1121     pub op: KleeneOp,
1122     /// The number of `MatchNt`s that appear in the sequence (and subsequences)
1123     pub num_captures: usize,
1124 }
1125
1126 /// A Kleene-style [repetition operator](http://en.wikipedia.org/wiki/Kleene_star)
1127 /// for token sequences.
1128 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1129 pub enum KleeneOp {
1130     ZeroOrMore,
1131     OneOrMore,
1132 }
1133
1134 /// When the main rust parser encounters a syntax-extension invocation, it
1135 /// parses the arguments to the invocation as a token-tree. This is a very
1136 /// loose structure, such that all sorts of different AST-fragments can
1137 /// be passed to syntax extensions using a uniform type.
1138 ///
1139 /// If the syntax extension is an MBE macro, it will attempt to match its
1140 /// LHS token tree against the provided token tree, and if it finds a
1141 /// match, will transcribe the RHS token tree, splicing in any captured
1142 /// macro_parser::matched_nonterminals into the `SubstNt`s it finds.
1143 ///
1144 /// The RHS of an MBE macro is the only place `SubstNt`s are substituted.
1145 /// Nothing special happens to misnamed or misplaced `SubstNt`s.
1146 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1147 pub enum TokenTree {
1148     /// A single token
1149     Token(Span, token::Token),
1150     /// A delimited sequence of token trees
1151     Delimited(Span, Rc<Delimited>),
1152
1153     // This only makes sense in MBE macros.
1154
1155     /// A kleene-style repetition sequence with a span
1156     // FIXME(eddyb) #12938 Use DST.
1157     Sequence(Span, Rc<SequenceRepetition>),
1158 }
1159
1160 impl TokenTree {
1161     pub fn len(&self) -> usize {
1162         match *self {
1163             TokenTree::Token(_, token::DocComment(name)) => {
1164                 match doc_comment_style(&name.as_str()) {
1165                     AttrStyle::Outer => 2,
1166                     AttrStyle::Inner => 3
1167                 }
1168             }
1169             TokenTree::Token(_, token::SpecialVarNt(..)) => 2,
1170             TokenTree::Token(_, token::MatchNt(..)) => 3,
1171             TokenTree::Delimited(_, ref delimed) => {
1172                 delimed.tts.len() + 2
1173             }
1174             TokenTree::Sequence(_, ref seq) => {
1175                 seq.tts.len()
1176             }
1177             TokenTree::Token(..) => 0
1178         }
1179     }
1180
1181     pub fn get_tt(&self, index: usize) -> TokenTree {
1182         match (self, index) {
1183             (&TokenTree::Token(sp, token::DocComment(_)), 0) => {
1184                 TokenTree::Token(sp, token::Pound)
1185             }
1186             (&TokenTree::Token(sp, token::DocComment(name)), 1)
1187             if doc_comment_style(&name.as_str()) == AttrStyle::Inner => {
1188                 TokenTree::Token(sp, token::Not)
1189             }
1190             (&TokenTree::Token(sp, token::DocComment(name)), _) => {
1191                 let stripped = strip_doc_comment_decoration(&name.as_str());
1192
1193                 // Searches for the occurrences of `"#*` and returns the minimum number of `#`s
1194                 // required to wrap the text.
1195                 let num_of_hashes = stripped.chars().scan(0, |cnt, x| {
1196                     *cnt = if x == '"' {
1197                         1
1198                     } else if *cnt != 0 && x == '#' {
1199                         *cnt + 1
1200                     } else {
1201                         0
1202                     };
1203                     Some(*cnt)
1204                 }).max().unwrap_or(0);
1205
1206                 TokenTree::Delimited(sp, Rc::new(Delimited {
1207                     delim: token::Bracket,
1208                     open_span: sp,
1209                     tts: vec![TokenTree::Token(sp, token::Ident(token::str_to_ident("doc"),
1210                                                                 token::Plain)),
1211                               TokenTree::Token(sp, token::Eq),
1212                               TokenTree::Token(sp, token::Literal(
1213                                   token::StrRaw(token::intern(&stripped), num_of_hashes), None))],
1214                     close_span: sp,
1215                 }))
1216             }
1217             (&TokenTree::Delimited(_, ref delimed), _) => {
1218                 if index == 0 {
1219                     return delimed.open_tt();
1220                 }
1221                 if index == delimed.tts.len() + 1 {
1222                     return delimed.close_tt();
1223                 }
1224                 delimed.tts[index - 1].clone()
1225             }
1226             (&TokenTree::Token(sp, token::SpecialVarNt(var)), _) => {
1227                 let v = [TokenTree::Token(sp, token::Dollar),
1228                          TokenTree::Token(sp, token::Ident(token::str_to_ident(var.as_str()),
1229                                                   token::Plain))];
1230                 v[index].clone()
1231             }
1232             (&TokenTree::Token(sp, token::MatchNt(name, kind, name_st, kind_st)), _) => {
1233                 let v = [TokenTree::Token(sp, token::SubstNt(name, name_st)),
1234                          TokenTree::Token(sp, token::Colon),
1235                          TokenTree::Token(sp, token::Ident(kind, kind_st))];
1236                 v[index].clone()
1237             }
1238             (&TokenTree::Sequence(_, ref seq), _) => {
1239                 seq.tts[index].clone()
1240             }
1241             _ => panic!("Cannot expand a token tree")
1242         }
1243     }
1244
1245     /// Returns the `Span` corresponding to this token tree.
1246     pub fn get_span(&self) -> Span {
1247         match *self {
1248             TokenTree::Token(span, _)     => span,
1249             TokenTree::Delimited(span, _) => span,
1250             TokenTree::Sequence(span, _)  => span,
1251         }
1252     }
1253
1254     /// Use this token tree as a matcher to parse given tts.
1255     pub fn parse(cx: &base::ExtCtxt, mtch: &[TokenTree], tts: &[TokenTree])
1256                  -> macro_parser::NamedParseResult {
1257         // `None` is because we're not interpolating
1258         let arg_rdr = lexer::new_tt_reader_with_doc_flag(&cx.parse_sess().span_diagnostic,
1259                                                          None,
1260                                                          None,
1261                                                          tts.iter().cloned().collect(),
1262                                                          true);
1263         macro_parser::parse(cx.parse_sess(), cx.cfg(), arg_rdr, mtch)
1264     }
1265 }
1266
1267 pub type Mac = Spanned<Mac_>;
1268
1269 /// Represents a macro invocation. The Path indicates which macro
1270 /// is being invoked, and the vector of token-trees contains the source
1271 /// of the macro invocation.
1272 ///
1273 /// NB: the additional ident for a macro_rules-style macro is actually
1274 /// stored in the enclosing item. Oog.
1275 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1276 pub struct Mac_ {
1277     pub path: Path,
1278     pub tts: Vec<TokenTree>,
1279     pub ctxt: SyntaxContext,
1280 }
1281
1282 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1283 pub enum StrStyle {
1284     /// A regular string, like `"foo"`
1285     Cooked,
1286     /// A raw string, like `r##"foo"##`
1287     ///
1288     /// The uint is the number of `#` symbols used
1289     Raw(usize)
1290 }
1291
1292 /// A literal
1293 pub type Lit = Spanned<LitKind>;
1294
1295 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1296 pub enum LitIntType {
1297     Signed(IntTy),
1298     Unsigned(UintTy),
1299     Unsuffixed,
1300 }
1301
1302 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1303 pub enum LitKind {
1304     /// A string literal (`"foo"`)
1305     Str(InternedString, StrStyle),
1306     /// A byte string (`b"foo"`)
1307     ByteStr(Rc<Vec<u8>>),
1308     /// A byte char (`b'f'`)
1309     Byte(u8),
1310     /// A character literal (`'a'`)
1311     Char(char),
1312     /// An integer literal (`1`)
1313     Int(u64, LitIntType),
1314     /// A float literal (`1f64` or `1E10f64`)
1315     Float(InternedString, FloatTy),
1316     /// A float literal without a suffix (`1.0 or 1.0E10`)
1317     FloatUnsuffixed(InternedString),
1318     /// A boolean literal
1319     Bool(bool),
1320 }
1321
1322 impl LitKind {
1323     /// Returns true if this literal is a string and false otherwise.
1324     pub fn is_str(&self) -> bool {
1325         match *self {
1326             LitKind::Str(..) => true,
1327             _ => false,
1328         }
1329     }
1330 }
1331
1332 // NB: If you change this, you'll probably want to change the corresponding
1333 // type structure in middle/ty.rs as well.
1334 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1335 pub struct MutTy {
1336     pub ty: P<Ty>,
1337     pub mutbl: Mutability,
1338 }
1339
1340 /// Represents a method's signature in a trait declaration,
1341 /// or in an implementation.
1342 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1343 pub struct MethodSig {
1344     pub unsafety: Unsafety,
1345     pub constness: Constness,
1346     pub abi: Abi,
1347     pub decl: P<FnDecl>,
1348     pub generics: Generics,
1349     pub explicit_self: ExplicitSelf,
1350 }
1351
1352 /// Represents an item declaration within a trait declaration,
1353 /// possibly including a default implementation. A trait item is
1354 /// either required (meaning it doesn't have an implementation, just a
1355 /// signature) or provided (meaning it has a default implementation).
1356 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1357 pub struct TraitItem {
1358     pub id: NodeId,
1359     pub ident: Ident,
1360     pub attrs: Vec<Attribute>,
1361     pub node: TraitItemKind,
1362     pub span: Span,
1363 }
1364
1365 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1366 pub enum TraitItemKind {
1367     Const(P<Ty>, Option<P<Expr>>),
1368     Method(MethodSig, Option<P<Block>>),
1369     Type(TyParamBounds, Option<P<Ty>>),
1370 }
1371
1372 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1373 pub struct ImplItem {
1374     pub id: NodeId,
1375     pub ident: Ident,
1376     pub vis: Visibility,
1377     pub defaultness: Defaultness,
1378     pub attrs: Vec<Attribute>,
1379     pub node: ImplItemKind,
1380     pub span: Span,
1381 }
1382
1383 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1384 pub enum ImplItemKind {
1385     Const(P<Ty>, P<Expr>),
1386     Method(MethodSig, P<Block>),
1387     Type(P<Ty>),
1388     Macro(Mac),
1389 }
1390
1391 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
1392 pub enum IntTy {
1393     Is,
1394     I8,
1395     I16,
1396     I32,
1397     I64,
1398 }
1399
1400 impl fmt::Debug for IntTy {
1401     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1402         fmt::Display::fmt(self, f)
1403     }
1404 }
1405
1406 impl fmt::Display for IntTy {
1407     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1408         write!(f, "{}", self.ty_to_string())
1409     }
1410 }
1411
1412 impl IntTy {
1413     pub fn ty_to_string(&self) -> &'static str {
1414         match *self {
1415             IntTy::Is => "isize",
1416             IntTy::I8 => "i8",
1417             IntTy::I16 => "i16",
1418             IntTy::I32 => "i32",
1419             IntTy::I64 => "i64"
1420         }
1421     }
1422
1423     pub fn val_to_string(&self, val: i64) -> String {
1424         // cast to a u64 so we can correctly print INT64_MIN. All integral types
1425         // are parsed as u64, so we wouldn't want to print an extra negative
1426         // sign.
1427         format!("{}{}", val as u64, self.ty_to_string())
1428     }
1429
1430     pub fn ty_max(&self) -> u64 {
1431         match *self {
1432             IntTy::I8 => 0x80,
1433             IntTy::I16 => 0x8000,
1434             IntTy::Is | IntTy::I32 => 0x80000000, // FIXME: actually ni about Is
1435             IntTy::I64 => 0x8000000000000000
1436         }
1437     }
1438
1439     pub fn bit_width(&self) -> Option<usize> {
1440         Some(match *self {
1441             IntTy::Is => return None,
1442             IntTy::I8 => 8,
1443             IntTy::I16 => 16,
1444             IntTy::I32 => 32,
1445             IntTy::I64 => 64,
1446         })
1447     }
1448 }
1449
1450 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
1451 pub enum UintTy {
1452     Us,
1453     U8,
1454     U16,
1455     U32,
1456     U64,
1457 }
1458
1459 impl UintTy {
1460     pub fn ty_to_string(&self) -> &'static str {
1461         match *self {
1462             UintTy::Us => "usize",
1463             UintTy::U8 => "u8",
1464             UintTy::U16 => "u16",
1465             UintTy::U32 => "u32",
1466             UintTy::U64 => "u64"
1467         }
1468     }
1469
1470     pub fn val_to_string(&self, val: u64) -> String {
1471         format!("{}{}", val, self.ty_to_string())
1472     }
1473
1474     pub fn ty_max(&self) -> u64 {
1475         match *self {
1476             UintTy::U8 => 0xff,
1477             UintTy::U16 => 0xffff,
1478             UintTy::Us | UintTy::U32 => 0xffffffff, // FIXME: actually ni about Us
1479             UintTy::U64 => 0xffffffffffffffff
1480         }
1481     }
1482
1483     pub fn bit_width(&self) -> Option<usize> {
1484         Some(match *self {
1485             UintTy::Us => return None,
1486             UintTy::U8 => 8,
1487             UintTy::U16 => 16,
1488             UintTy::U32 => 32,
1489             UintTy::U64 => 64,
1490         })
1491     }
1492 }
1493
1494 impl fmt::Debug for UintTy {
1495     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1496         fmt::Display::fmt(self, f)
1497     }
1498 }
1499
1500 impl fmt::Display for UintTy {
1501     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1502         write!(f, "{}", self.ty_to_string())
1503     }
1504 }
1505
1506 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
1507 pub enum FloatTy {
1508     F32,
1509     F64,
1510 }
1511
1512 impl fmt::Debug for FloatTy {
1513     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1514         fmt::Display::fmt(self, f)
1515     }
1516 }
1517
1518 impl fmt::Display for FloatTy {
1519     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1520         write!(f, "{}", self.ty_to_string())
1521     }
1522 }
1523
1524 impl FloatTy {
1525     pub fn ty_to_string(&self) -> &'static str {
1526         match *self {
1527             FloatTy::F32 => "f32",
1528             FloatTy::F64 => "f64",
1529         }
1530     }
1531
1532     pub fn bit_width(&self) -> usize {
1533         match *self {
1534             FloatTy::F32 => 32,
1535             FloatTy::F64 => 64,
1536         }
1537     }
1538 }
1539
1540 // Bind a type to an associated type: `A=Foo`.
1541 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1542 pub struct TypeBinding {
1543     pub id: NodeId,
1544     pub ident: Ident,
1545     pub ty: P<Ty>,
1546     pub span: Span,
1547 }
1548
1549 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
1550 pub struct Ty {
1551     pub id: NodeId,
1552     pub node: TyKind,
1553     pub span: Span,
1554 }
1555
1556 impl fmt::Debug for Ty {
1557     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1558         write!(f, "type({})", pprust::ty_to_string(self))
1559     }
1560 }
1561
1562 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1563 pub struct BareFnTy {
1564     pub unsafety: Unsafety,
1565     pub abi: Abi,
1566     pub lifetimes: Vec<LifetimeDef>,
1567     pub decl: P<FnDecl>
1568 }
1569
1570 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1571 /// The different kinds of types recognized by the compiler
1572 pub enum TyKind {
1573     Vec(P<Ty>),
1574     /// A fixed length array (`[T; n]`)
1575     FixedLengthVec(P<Ty>, P<Expr>),
1576     /// A raw pointer (`*const T` or `*mut T`)
1577     Ptr(MutTy),
1578     /// A reference (`&'a T` or `&'a mut T`)
1579     Rptr(Option<Lifetime>, MutTy),
1580     /// A bare function (e.g. `fn(usize) -> bool`)
1581     BareFn(P<BareFnTy>),
1582     /// A tuple (`(A, B, C, D,...)`)
1583     Tup(Vec<P<Ty>> ),
1584     /// A path (`module::module::...::Type`), optionally
1585     /// "qualified", e.g. `<Vec<T> as SomeTrait>::SomeType`.
1586     ///
1587     /// Type parameters are stored in the Path itself
1588     Path(Option<QSelf>, Path),
1589     /// Something like `A+B`. Note that `B` must always be a path.
1590     ObjectSum(P<Ty>, TyParamBounds),
1591     /// A type like `for<'a> Foo<&'a Bar>`
1592     PolyTraitRef(TyParamBounds),
1593     /// No-op; kept solely so that we can pretty-print faithfully
1594     Paren(P<Ty>),
1595     /// Unused for now
1596     Typeof(P<Expr>),
1597     /// TyKind::Infer means the type should be inferred instead of it having been
1598     /// specified. This can appear anywhere in a type.
1599     Infer,
1600     // A macro in the type position.
1601     Mac(Mac),
1602 }
1603
1604 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1605 pub enum AsmDialect {
1606     Att,
1607     Intel,
1608 }
1609
1610 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1611 pub struct InlineAsmOutput {
1612     pub constraint: InternedString,
1613     pub expr: P<Expr>,
1614     pub is_rw: bool,
1615     pub is_indirect: bool,
1616 }
1617
1618 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1619 pub struct InlineAsm {
1620     pub asm: InternedString,
1621     pub asm_str_style: StrStyle,
1622     pub outputs: Vec<InlineAsmOutput>,
1623     pub inputs: Vec<(InternedString, P<Expr>)>,
1624     pub clobbers: Vec<InternedString>,
1625     pub volatile: bool,
1626     pub alignstack: bool,
1627     pub dialect: AsmDialect,
1628     pub expn_id: ExpnId,
1629 }
1630
1631 /// represents an argument in a function header
1632 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1633 pub struct Arg {
1634     pub ty: P<Ty>,
1635     pub pat: P<Pat>,
1636     pub id: NodeId,
1637 }
1638
1639 impl Arg {
1640     pub fn new_self(span: Span, mutability: Mutability, self_ident: Ident) -> Arg {
1641         let path = Spanned{span:span,node:self_ident};
1642         Arg {
1643             // HACK(eddyb) fake type for the self argument.
1644             ty: P(Ty {
1645                 id: DUMMY_NODE_ID,
1646                 node: TyKind::Infer,
1647                 span: DUMMY_SP,
1648             }),
1649             pat: P(Pat {
1650                 id: DUMMY_NODE_ID,
1651                 node: PatKind::Ident(BindingMode::ByValue(mutability), path, None),
1652                 span: span
1653             }),
1654             id: DUMMY_NODE_ID
1655         }
1656     }
1657 }
1658
1659 /// Represents the header (not the body) of a function declaration
1660 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1661 pub struct FnDecl {
1662     pub inputs: Vec<Arg>,
1663     pub output: FunctionRetTy,
1664     pub variadic: bool
1665 }
1666
1667 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1668 pub enum Unsafety {
1669     Unsafe,
1670     Normal,
1671 }
1672
1673 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1674 pub enum Constness {
1675     Const,
1676     NotConst,
1677 }
1678
1679 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1680 pub enum Defaultness {
1681     Default,
1682     Final,
1683 }
1684
1685 impl fmt::Display for Unsafety {
1686     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1687         fmt::Display::fmt(match *self {
1688             Unsafety::Normal => "normal",
1689             Unsafety::Unsafe => "unsafe",
1690         }, f)
1691     }
1692 }
1693
1694 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
1695 pub enum ImplPolarity {
1696     /// `impl Trait for Type`
1697     Positive,
1698     /// `impl !Trait for Type`
1699     Negative,
1700 }
1701
1702 impl fmt::Debug for ImplPolarity {
1703     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1704         match *self {
1705             ImplPolarity::Positive => "positive".fmt(f),
1706             ImplPolarity::Negative => "negative".fmt(f),
1707         }
1708     }
1709 }
1710
1711
1712 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1713 pub enum FunctionRetTy {
1714     /// Functions with return type `!`that always
1715     /// raise an error or exit (i.e. never return to the caller)
1716     None(Span),
1717     /// Return type is not specified.
1718     ///
1719     /// Functions default to `()` and
1720     /// closures default to inference. Span points to where return
1721     /// type would be inserted.
1722     Default(Span),
1723     /// Everything else
1724     Ty(P<Ty>),
1725 }
1726
1727 impl FunctionRetTy {
1728     pub fn span(&self) -> Span {
1729         match *self {
1730             FunctionRetTy::None(span) => span,
1731             FunctionRetTy::Default(span) => span,
1732             FunctionRetTy::Ty(ref ty) => ty.span,
1733         }
1734     }
1735 }
1736
1737 /// Represents the kind of 'self' associated with a method
1738 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1739 pub enum SelfKind {
1740     /// No self
1741     Static,
1742     /// `self`
1743     Value(Ident),
1744     /// `&'lt self`, `&'lt mut self`
1745     Region(Option<Lifetime>, Mutability, Ident),
1746     /// `self: TYPE`
1747     Explicit(P<Ty>, Ident),
1748 }
1749
1750 pub type ExplicitSelf = Spanned<SelfKind>;
1751
1752 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1753 pub struct Mod {
1754     /// A span from the first token past `{` to the last token until `}`.
1755     /// For `mod foo;`, the inner span ranges from the first token
1756     /// to the last token in the external file.
1757     pub inner: Span,
1758     pub items: Vec<P<Item>>,
1759 }
1760
1761 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1762 pub struct ForeignMod {
1763     pub abi: Abi,
1764     pub items: Vec<ForeignItem>,
1765 }
1766
1767 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1768 pub struct EnumDef {
1769     pub variants: Vec<Variant>,
1770 }
1771
1772 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1773 pub struct Variant_ {
1774     pub name: Ident,
1775     pub attrs: Vec<Attribute>,
1776     pub data: VariantData,
1777     /// Explicit discriminant, eg `Foo = 1`
1778     pub disr_expr: Option<P<Expr>>,
1779 }
1780
1781 pub type Variant = Spanned<Variant_>;
1782
1783 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1784 pub enum PathListItemKind {
1785     Ident {
1786         name: Ident,
1787         /// renamed in list, eg `use foo::{bar as baz};`
1788         rename: Option<Ident>,
1789         id: NodeId
1790     },
1791     Mod {
1792         /// renamed in list, eg `use foo::{self as baz};`
1793         rename: Option<Ident>,
1794         id: NodeId
1795     }
1796 }
1797
1798 impl PathListItemKind {
1799     pub fn id(&self) -> NodeId {
1800         match *self {
1801             PathListItemKind::Ident { id, .. } | PathListItemKind::Mod { id, .. } => id
1802         }
1803     }
1804
1805     pub fn name(&self) -> Option<Ident> {
1806         match *self {
1807             PathListItemKind::Ident { name, .. } => Some(name),
1808             PathListItemKind::Mod { .. } => None,
1809         }
1810     }
1811
1812     pub fn rename(&self) -> Option<Ident> {
1813         match *self {
1814             PathListItemKind::Ident { rename, .. } | PathListItemKind::Mod { rename, .. } => rename
1815         }
1816     }
1817 }
1818
1819 pub type PathListItem = Spanned<PathListItemKind>;
1820
1821 pub type ViewPath = Spanned<ViewPath_>;
1822
1823 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1824 pub enum ViewPath_ {
1825
1826     /// `foo::bar::baz as quux`
1827     ///
1828     /// or just
1829     ///
1830     /// `foo::bar::baz` (with `as baz` implicitly on the right)
1831     ViewPathSimple(Ident, Path),
1832
1833     /// `foo::bar::*`
1834     ViewPathGlob(Path),
1835
1836     /// `foo::bar::{a,b,c}`
1837     ViewPathList(Path, Vec<PathListItem>)
1838 }
1839
1840 /// Meta-data associated with an item
1841 pub type Attribute = Spanned<Attribute_>;
1842
1843 /// Distinguishes between Attributes that decorate items and Attributes that
1844 /// are contained as statements within items. These two cases need to be
1845 /// distinguished for pretty-printing.
1846 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1847 pub enum AttrStyle {
1848     Outer,
1849     Inner,
1850 }
1851
1852 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1853 pub struct AttrId(pub usize);
1854
1855 /// Doc-comments are promoted to attributes that have is_sugared_doc = true
1856 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1857 pub struct Attribute_ {
1858     pub id: AttrId,
1859     pub style: AttrStyle,
1860     pub value: P<MetaItem>,
1861     pub is_sugared_doc: bool,
1862 }
1863
1864 /// TraitRef's appear in impls.
1865 ///
1866 /// resolve maps each TraitRef's ref_id to its defining trait; that's all
1867 /// that the ref_id is for. The impl_id maps to the "self type" of this impl.
1868 /// If this impl is an ItemKind::Impl, the impl_id is redundant (it could be the
1869 /// same as the impl's node id).
1870 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1871 pub struct TraitRef {
1872     pub path: Path,
1873     pub ref_id: NodeId,
1874 }
1875
1876 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1877 pub struct PolyTraitRef {
1878     /// The `'a` in `<'a> Foo<&'a T>`
1879     pub bound_lifetimes: Vec<LifetimeDef>,
1880
1881     /// The `Foo<&'a T>` in `<'a> Foo<&'a T>`
1882     pub trait_ref: TraitRef,
1883
1884     pub span: Span,
1885 }
1886
1887 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1888 pub enum Visibility {
1889     Public,
1890     Crate,
1891     Restricted { path: P<Path>, id: NodeId },
1892     Inherited,
1893 }
1894
1895 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1896 pub struct StructField {
1897     pub span: Span,
1898     pub ident: Option<Ident>,
1899     pub vis: Visibility,
1900     pub id: NodeId,
1901     pub ty: P<Ty>,
1902     pub attrs: Vec<Attribute>,
1903 }
1904
1905 /// Fields and Ids of enum variants and structs
1906 ///
1907 /// For enum variants: `NodeId` represents both an Id of the variant itself (relevant for all
1908 /// variant kinds) and an Id of the variant's constructor (not relevant for `Struct`-variants).
1909 /// One shared Id can be successfully used for these two purposes.
1910 /// Id of the whole enum lives in `Item`.
1911 ///
1912 /// For structs: `NodeId` represents an Id of the structure's constructor, so it is not actually
1913 /// used for `Struct`-structs (but still presents). Structures don't have an analogue of "Id of
1914 /// the variant itself" from enum variants.
1915 /// Id of the whole struct lives in `Item`.
1916 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1917 pub enum VariantData {
1918     Struct(Vec<StructField>, NodeId),
1919     Tuple(Vec<StructField>, NodeId),
1920     Unit(NodeId),
1921 }
1922
1923 impl VariantData {
1924     pub fn fields(&self) -> &[StructField] {
1925         match *self {
1926             VariantData::Struct(ref fields, _) | VariantData::Tuple(ref fields, _) => fields,
1927             _ => &[],
1928         }
1929     }
1930     pub fn id(&self) -> NodeId {
1931         match *self {
1932             VariantData::Struct(_, id) | VariantData::Tuple(_, id) | VariantData::Unit(id) => id
1933         }
1934     }
1935     pub fn is_struct(&self) -> bool {
1936         if let VariantData::Struct(..) = *self { true } else { false }
1937     }
1938     pub fn is_tuple(&self) -> bool {
1939         if let VariantData::Tuple(..) = *self { true } else { false }
1940     }
1941     pub fn is_unit(&self) -> bool {
1942         if let VariantData::Unit(..) = *self { true } else { false }
1943     }
1944 }
1945
1946 /*
1947   FIXME (#3300): Should allow items to be anonymous. Right now
1948   we just use dummy names for anon items.
1949  */
1950 /// An item
1951 ///
1952 /// The name might be a dummy name in case of anonymous items
1953 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1954 pub struct Item {
1955     pub ident: Ident,
1956     pub attrs: Vec<Attribute>,
1957     pub id: NodeId,
1958     pub node: ItemKind,
1959     pub vis: Visibility,
1960     pub span: Span,
1961 }
1962
1963 impl Item {
1964     pub fn attrs(&self) -> &[Attribute] {
1965         &self.attrs
1966     }
1967 }
1968
1969 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1970 pub enum ItemKind {
1971     /// An`extern crate` item, with optional original crate name,
1972     ///
1973     /// e.g. `extern crate foo` or `extern crate foo_bar as foo`
1974     ExternCrate(Option<Name>),
1975     /// A `use` or `pub use` item
1976     Use(P<ViewPath>),
1977
1978     /// A `static` item
1979     Static(P<Ty>, Mutability, P<Expr>),
1980     /// A `const` item
1981     Const(P<Ty>, P<Expr>),
1982     /// A function declaration
1983     Fn(P<FnDecl>, Unsafety, Constness, Abi, Generics, P<Block>),
1984     /// A module
1985     Mod(Mod),
1986     /// An external module
1987     ForeignMod(ForeignMod),
1988     /// A type alias, e.g. `type Foo = Bar<u8>`
1989     Ty(P<Ty>, Generics),
1990     /// An enum definition, e.g. `enum Foo<A, B> {C<A>, D<B>}`
1991     Enum(EnumDef, Generics),
1992     /// A struct definition, e.g. `struct Foo<A> {x: A}`
1993     Struct(VariantData, Generics),
1994     /// Represents a Trait Declaration
1995     Trait(Unsafety,
1996               Generics,
1997               TyParamBounds,
1998               Vec<TraitItem>),
1999
2000     // Default trait implementations
2001     ///
2002     // `impl Trait for .. {}`
2003     DefaultImpl(Unsafety, TraitRef),
2004     /// An implementation, eg `impl<A> Trait for Foo { .. }`
2005     Impl(Unsafety,
2006              ImplPolarity,
2007              Generics,
2008              Option<TraitRef>, // (optional) trait this impl implements
2009              P<Ty>, // self
2010              Vec<ImplItem>),
2011     /// A macro invocation (which includes macro definition)
2012     Mac(Mac),
2013 }
2014
2015 impl ItemKind {
2016     pub fn descriptive_variant(&self) -> &str {
2017         match *self {
2018             ItemKind::ExternCrate(..) => "extern crate",
2019             ItemKind::Use(..) => "use",
2020             ItemKind::Static(..) => "static item",
2021             ItemKind::Const(..) => "constant item",
2022             ItemKind::Fn(..) => "function",
2023             ItemKind::Mod(..) => "module",
2024             ItemKind::ForeignMod(..) => "foreign module",
2025             ItemKind::Ty(..) => "type alias",
2026             ItemKind::Enum(..) => "enum",
2027             ItemKind::Struct(..) => "struct",
2028             ItemKind::Trait(..) => "trait",
2029             ItemKind::Mac(..) |
2030             ItemKind::Impl(..) |
2031             ItemKind::DefaultImpl(..) => "item"
2032         }
2033     }
2034 }
2035
2036 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
2037 pub struct ForeignItem {
2038     pub ident: Ident,
2039     pub attrs: Vec<Attribute>,
2040     pub node: ForeignItemKind,
2041     pub id: NodeId,
2042     pub span: Span,
2043     pub vis: Visibility,
2044 }
2045
2046 /// An item within an `extern` block
2047 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
2048 pub enum ForeignItemKind {
2049     /// A foreign function
2050     Fn(P<FnDecl>, Generics),
2051     /// A foreign static item (`static ext: u8`), with optional mutability
2052     /// (the boolean is true when mutable)
2053     Static(P<Ty>, bool),
2054 }
2055
2056 impl ForeignItemKind {
2057     pub fn descriptive_variant(&self) -> &str {
2058         match *self {
2059             ForeignItemKind::Fn(..) => "foreign function",
2060             ForeignItemKind::Static(..) => "foreign static item"
2061         }
2062     }
2063 }
2064
2065 /// A macro definition, in this crate or imported from another.
2066 ///
2067 /// Not parsed directly, but created on macro import or `macro_rules!` expansion.
2068 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
2069 pub struct MacroDef {
2070     pub ident: Ident,
2071     pub attrs: Vec<Attribute>,
2072     pub id: NodeId,
2073     pub span: Span,
2074     pub imported_from: Option<Ident>,
2075     pub export: bool,
2076     pub use_locally: bool,
2077     pub allow_internal_unstable: bool,
2078     pub body: Vec<TokenTree>,
2079 }
2080
2081 #[cfg(test)]
2082 mod tests {
2083     use serialize;
2084     use super::*;
2085
2086     // are ASTs encodable?
2087     #[test]
2088     fn check_asts_encodable() {
2089         fn assert_encodable<T: serialize::Encodable>() {}
2090         assert_encodable::<Crate>();
2091     }
2092 }