src/librustc_front/intravisit.rs

   1 // Copyright 2012-2015 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 //! HIR walker. Each overridden visit method has full control over what
  12 //! happens with its node, it can do its own traversal of the node's children,
  13 //! call `intravisit::walk_*` to apply the default traversal algorithm, or prevent
  14 //! deeper traversal by doing nothing.
  15 //!
  16 //! When visiting the HIR, the contents of nested items are NOT visited
  17 //! by default. This is different from the AST visitor, which does a deep walk.
  18 //! Hence this module is called `intravisit`; see the method `visit_nested_item`
  19 //! for more details.
  20 //!
  21 //! Note: it is an important invariant that the default visitor walks
  22 //! the body of a function in "execution order" (more concretely,
  23 //! reverse post-order with respect to the CFG implied by the AST),
  24 //! meaning that if AST node A may execute before AST node B, then A
  25 //! is visited first.  The borrow checker in particular relies on this
  26 //! property.
  27
  28 use syntax::abi::Abi;
  29 use syntax::ast::{NodeId, CRATE_NODE_ID, Name, Attribute};
  30 use syntax::codemap::Span;
  31 use hir::*;
  32
  33 #[derive(Copy, Clone, PartialEq, Eq)]
  34 pub enum FnKind<'a> {
  35     /// fn foo() or extern "Abi" fn foo()
  36     ItemFn(Name, &'a Generics, Unsafety, Constness, Abi, Visibility),
  37
  38     /// fn foo(&self)
  39     Method(Name, &'a MethodSig, Option<Visibility>),
  40
  41     /// |x, y| {}
  42     Closure,
  43 }
  44
  45 /// Each method of the Visitor trait is a hook to be potentially
  46 /// overridden.  Each method's default implementation recursively visits
  47 /// the substructure of the input via the corresponding `walk` method;
  48 /// e.g. the `visit_mod` method by default calls `intravisit::walk_mod`.
  49 ///
  50 /// Note that this visitor does NOT visit nested items by default
  51 /// (this is why the module is called `intravisit`, to distinguish it
  52 /// from the AST's `visit` module, which acts differently). If you
  53 /// simply want to visit all items in the crate in some order, you
  54 /// should call `Crate::visit_all_items`. Otherwise, see the comment
  55 /// on `visit_nested_item` for details on how to visit nested items.
  56 ///
  57 /// If you want to ensure that your code handles every variant
  58 /// explicitly, you need to override each method.  (And you also need
  59 /// to monitor future changes to `Visitor` in case a new method with a
  60 /// new default implementation gets introduced.)
  61 pub trait Visitor<'v> : Sized {
  62     ///////////////////////////////////////////////////////////////////////////
  63     // Nested items.
  64
  65     /// Invoked when a nested item is encountered. By default, does
  66     /// nothing. If you want a deep walk, you need to override to
  67     /// fetch the item contents. But most of the time, it is easier
  68     /// (and better) to invoke `Crate::visit_all_items`, which visits
  69     /// all items in the crate in some order (but doesn't respect
  70     /// nesting).
  71     #[allow(unused_variables)]
  72     fn visit_nested_item(&mut self, id: ItemId) {
  73     }
  74
  75     /// Visit the top-level item and (optionally) nested items. See
  76     /// `visit_nested_item` for details.
  77     fn visit_item(&mut self, i: &'v Item) {
  78         walk_item(self, i)
  79     }
  80
  81     ///////////////////////////////////////////////////////////////////////////
  82
  83     fn visit_name(&mut self, _span: Span, _name: Name) {
  84         // Nothing to do.
  85     }
  86     fn visit_ident(&mut self, span: Span, ident: Ident) {
  87         walk_ident(self, span, ident);
  88     }
  89     fn visit_mod(&mut self, m: &'v Mod, _s: Span, _n: NodeId) {
  90         walk_mod(self, m)
  91     }
  92     fn visit_foreign_item(&mut self, i: &'v ForeignItem) {
  93         walk_foreign_item(self, i)
  94     }
  95     fn visit_local(&mut self, l: &'v Local) {
  96         walk_local(self, l)
  97     }
  98     fn visit_block(&mut self, b: &'v Block) {
  99         walk_block(self, b)
 100     }
 101     fn visit_stmt(&mut self, s: &'v Stmt) {
 102         walk_stmt(self, s)
 103     }
 104     fn visit_arm(&mut self, a: &'v Arm) {
 105         walk_arm(self, a)
 106     }
 107     fn visit_pat(&mut self, p: &'v Pat) {
 108         walk_pat(self, p)
 109     }
 110     fn visit_decl(&mut self, d: &'v Decl) {
 111         walk_decl(self, d)
 112     }
 113     fn visit_expr(&mut self, ex: &'v Expr) {
 114         walk_expr(self, ex)
 115     }
 116     fn visit_expr_post(&mut self, _ex: &'v Expr) {
 117     }
 118     fn visit_ty(&mut self, t: &'v Ty) {
 119         walk_ty(self, t)
 120     }
 121     fn visit_generics(&mut self, g: &'v Generics) {
 122         walk_generics(self, g)
 123     }
 124     fn visit_fn(&mut self, fk: FnKind<'v>, fd: &'v FnDecl, b: &'v Block, s: Span, _: NodeId) {
 125         walk_fn(self, fk, fd, b, s)
 126     }
 127     fn visit_trait_item(&mut self, ti: &'v TraitItem) {
 128         walk_trait_item(self, ti)
 129     }
 130     fn visit_impl_item(&mut self, ii: &'v ImplItem) {
 131         walk_impl_item(self, ii)
 132     }
 133     fn visit_trait_ref(&mut self, t: &'v TraitRef) {
 134         walk_trait_ref(self, t)
 135     }
 136     fn visit_ty_param_bound(&mut self, bounds: &'v TyParamBound) {
 137         walk_ty_param_bound(self, bounds)
 138     }
 139     fn visit_poly_trait_ref(&mut self, t: &'v PolyTraitRef, m: &'v TraitBoundModifier) {
 140         walk_poly_trait_ref(self, t, m)
 141     }
 142     fn visit_variant_data(&mut self,
 143                           s: &'v VariantData,
 144                           _: Name,
 145                           _: &'v Generics,
 146                           _: NodeId,
 147                           _: Span) {
 148         walk_struct_def(self, s)
 149     }
 150     fn visit_struct_field(&mut self, s: &'v StructField) {
 151         walk_struct_field(self, s)
 152     }
 153     fn visit_enum_def(&mut self,
 154                       enum_definition: &'v EnumDef,
 155                       generics: &'v Generics,
 156                       item_id: NodeId,
 157                       _: Span) {
 158         walk_enum_def(self, enum_definition, generics, item_id)
 159     }
 160     fn visit_variant(&mut self, v: &'v Variant, g: &'v Generics, item_id: NodeId) {
 161         walk_variant(self, v, g, item_id)
 162     }
 163     fn visit_lifetime(&mut self, lifetime: &'v Lifetime) {
 164         walk_lifetime(self, lifetime)
 165     }
 166     fn visit_lifetime_def(&mut self, lifetime: &'v LifetimeDef) {
 167         walk_lifetime_def(self, lifetime)
 168     }
 169     fn visit_explicit_self(&mut self, es: &'v ExplicitSelf) {
 170         walk_explicit_self(self, es)
 171     }
 172     fn visit_path(&mut self, path: &'v Path, _id: NodeId) {
 173         walk_path(self, path)
 174     }
 175     fn visit_path_list_item(&mut self, prefix: &'v Path, item: &'v PathListItem) {
 176         walk_path_list_item(self, prefix, item)
 177     }
 178     fn visit_path_segment(&mut self, path_span: Span, path_segment: &'v PathSegment) {
 179         walk_path_segment(self, path_span, path_segment)
 180     }
 181     fn visit_path_parameters(&mut self, path_span: Span, path_parameters: &'v PathParameters) {
 182         walk_path_parameters(self, path_span, path_parameters)
 183     }
 184     fn visit_assoc_type_binding(&mut self, type_binding: &'v TypeBinding) {
 185         walk_assoc_type_binding(self, type_binding)
 186     }
 187     fn visit_attribute(&mut self, _attr: &'v Attribute) {
 188     }
 189     fn visit_macro_def(&mut self, macro_def: &'v MacroDef) {
 190         walk_macro_def(self, macro_def)
 191     }
 192 }
 193
 194 pub fn walk_opt_name<'v, V: Visitor<'v>>(visitor: &mut V, span: Span, opt_name: Option<Name>) {
 195     for name in opt_name {
 196         visitor.visit_name(span, name);
 197     }
 198 }
 199
 200 pub fn walk_opt_ident<'v, V: Visitor<'v>>(visitor: &mut V, span: Span, opt_ident: Option<Ident>) {
 201     for ident in opt_ident {
 202         visitor.visit_ident(span, ident);
 203     }
 204 }
 205
 206 pub fn walk_ident<'v, V: Visitor<'v>>(visitor: &mut V, span: Span, ident: Ident) {
 207     visitor.visit_name(span, ident.name);
 208 }
 209
 210 /// Walks the contents of a crate. See also `Crate::visit_all_items`.
 211 pub fn walk_crate<'v, V: Visitor<'v>>(visitor: &mut V, krate: &'v Crate) {
 212     visitor.visit_mod(&krate.module, krate.span, CRATE_NODE_ID);
 213     walk_list!(visitor, visit_attribute, &krate.attrs);
 214     walk_list!(visitor, visit_macro_def, &krate.exported_macros);
 215 }
 216
 217 pub fn walk_macro_def<'v, V: Visitor<'v>>(visitor: &mut V, macro_def: &'v MacroDef) {
 218     visitor.visit_name(macro_def.span, macro_def.name);
 219     walk_opt_name(visitor, macro_def.span, macro_def.imported_from);
 220     walk_list!(visitor, visit_attribute, &macro_def.attrs);
 221 }
 222
 223 pub fn walk_mod<'v, V: Visitor<'v>>(visitor: &mut V, module: &'v Mod) {
 224     for &item_id in &module.item_ids {
 225         visitor.visit_nested_item(item_id);
 226     }
 227 }
 228
 229 pub fn walk_local<'v, V: Visitor<'v>>(visitor: &mut V, local: &'v Local) {
 230     visitor.visit_pat(&local.pat);
 231     walk_list!(visitor, visit_ty, &local.ty);
 232     walk_list!(visitor, visit_expr, &local.init);
 233 }
 234
 235 pub fn walk_lifetime<'v, V: Visitor<'v>>(visitor: &mut V, lifetime: &'v Lifetime) {
 236     visitor.visit_name(lifetime.span, lifetime.name);
 237 }
 238
 239 pub fn walk_lifetime_def<'v, V: Visitor<'v>>(visitor: &mut V, lifetime_def: &'v LifetimeDef) {
 240     visitor.visit_lifetime(&lifetime_def.lifetime);
 241     walk_list!(visitor, visit_lifetime, &lifetime_def.bounds);
 242 }
 243
 244 pub fn walk_explicit_self<'v, V: Visitor<'v>>(visitor: &mut V, explicit_self: &'v ExplicitSelf) {
 245     match explicit_self.node {
 246         SelfStatic => {}
 247         SelfValue(name) => {
 248             visitor.visit_name(explicit_self.span, name)
 249         }
 250         SelfRegion(ref opt_lifetime, _, name) => {
 251             visitor.visit_name(explicit_self.span, name);
 252             walk_list!(visitor, visit_lifetime, opt_lifetime);
 253         }
 254         SelfExplicit(ref typ, name) => {
 255             visitor.visit_name(explicit_self.span, name);
 256             visitor.visit_ty(typ)
 257         }
 258     }
 259 }
 260
 261 pub fn walk_poly_trait_ref<'v, V>(visitor: &mut V,
 262                                   trait_ref: &'v PolyTraitRef,
 263                                   _modifier: &'v TraitBoundModifier)
 264     where V: Visitor<'v>
 265 {
 266     walk_list!(visitor, visit_lifetime_def, &trait_ref.bound_lifetimes);
 267     visitor.visit_trait_ref(&trait_ref.trait_ref);
 268 }
 269
 270 pub fn walk_trait_ref<'v, V>(visitor: &mut V, trait_ref: &'v TraitRef)
 271     where V: Visitor<'v>
 272 {
 273     visitor.visit_path(&trait_ref.path, trait_ref.ref_id)
 274 }
 275
 276 pub fn walk_item<'v, V: Visitor<'v>>(visitor: &mut V, item: &'v Item) {
 277     visitor.visit_name(item.span, item.name);
 278     match item.node {
 279         ItemExternCrate(opt_name) => {
 280             walk_opt_name(visitor, item.span, opt_name)
 281         }
 282         ItemUse(ref vp) => {
 283             match vp.node {
 284                 ViewPathSimple(name, ref path) => {
 285                     visitor.visit_name(vp.span, name);
 286                     visitor.visit_path(path, item.id);
 287                 }
 288                 ViewPathGlob(ref path) => {
 289                     visitor.visit_path(path, item.id);
 290                 }
 291                 ViewPathList(ref prefix, ref list) => {
 292                     if !list.is_empty() {
 293                         for item in list {
 294                             visitor.visit_path_list_item(prefix, item)
 295                         }
 296                     } else {
 297                         visitor.visit_path(prefix, item.id);
 298                     }
 299                 }
 300             }
 301         }
 302         ItemStatic(ref typ, _, ref expr) |
 303         ItemConst(ref typ, ref expr) => {
 304             visitor.visit_ty(typ);
 305             visitor.visit_expr(expr);
 306         }
 307         ItemFn(ref declaration, unsafety, constness, abi, ref generics, ref body) => {
 308             visitor.visit_fn(FnKind::ItemFn(item.name,
 309                                             generics,
 310                                             unsafety,
 311                                             constness,
 312                                             abi,
 313                                             item.vis),
 314                              declaration,
 315                              body,
 316                              item.span,
 317                              item.id)
 318         }
 319         ItemMod(ref module) => {
 320             visitor.visit_mod(module, item.span, item.id)
 321         }
 322         ItemForeignMod(ref foreign_module) => {
 323             walk_list!(visitor, visit_foreign_item, &foreign_module.items);
 324         }
 325         ItemTy(ref typ, ref type_parameters) => {
 326             visitor.visit_ty(typ);
 327             visitor.visit_generics(type_parameters)
 328         }
 329         ItemEnum(ref enum_definition, ref type_parameters) => {
 330             visitor.visit_generics(type_parameters);
 331             visitor.visit_enum_def(enum_definition, type_parameters, item.id, item.span)
 332         }
 333         ItemDefaultImpl(_, ref trait_ref) => {
 334             visitor.visit_trait_ref(trait_ref)
 335         }
 336         ItemImpl(_, _, ref type_parameters, ref opt_trait_reference, ref typ, ref impl_items) => {
 337             visitor.visit_generics(type_parameters);
 338             walk_list!(visitor, visit_trait_ref, opt_trait_reference);
 339             visitor.visit_ty(typ);
 340             walk_list!(visitor, visit_impl_item, impl_items);
 341         }
 342         ItemStruct(ref struct_definition, ref generics) => {
 343             visitor.visit_generics(generics);
 344             visitor.visit_variant_data(struct_definition, item.name, generics, item.id, item.span);
 345         }
 346         ItemTrait(_, ref generics, ref bounds, ref methods) => {
 347             visitor.visit_generics(generics);
 348             walk_list!(visitor, visit_ty_param_bound, bounds);
 349             walk_list!(visitor, visit_trait_item, methods);
 350         }
 351     }
 352     walk_list!(visitor, visit_attribute, &item.attrs);
 353 }
 354
 355 pub fn walk_enum_def<'v, V: Visitor<'v>>(visitor: &mut V,
 356                                          enum_definition: &'v EnumDef,
 357                                          generics: &'v Generics,
 358                                          item_id: NodeId) {
 359     walk_list!(visitor,
 360                visit_variant,
 361                &enum_definition.variants,
 362                generics,
 363                item_id);
 364 }
 365
 366 pub fn walk_variant<'v, V: Visitor<'v>>(visitor: &mut V,
 367                                         variant: &'v Variant,
 368                                         generics: &'v Generics,
 369                                         item_id: NodeId) {
 370     visitor.visit_name(variant.span, variant.node.name);
 371     visitor.visit_variant_data(&variant.node.data,
 372                                variant.node.name,
 373                                generics,
 374                                item_id,
 375                                variant.span);
 376     walk_list!(visitor, visit_expr, &variant.node.disr_expr);
 377     walk_list!(visitor, visit_attribute, &variant.node.attrs);
 378 }
 379
 380 pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty) {
 381     match typ.node {
 382         TyVec(ref ty) => {
 383             visitor.visit_ty(ty)
 384         }
 385         TyPtr(ref mutable_type) => {
 386             visitor.visit_ty(&mutable_type.ty)
 387         }
 388         TyRptr(ref opt_lifetime, ref mutable_type) => {
 389             walk_list!(visitor, visit_lifetime, opt_lifetime);
 390             visitor.visit_ty(&mutable_type.ty)
 391         }
 392         TyTup(ref tuple_element_types) => {
 393             walk_list!(visitor, visit_ty, tuple_element_types);
 394         }
 395         TyBareFn(ref function_declaration) => {
 396             walk_fn_decl(visitor, &function_declaration.decl);
 397             walk_list!(visitor, visit_lifetime_def, &function_declaration.lifetimes);
 398         }
 399         TyPath(ref maybe_qself, ref path) => {
 400             if let Some(ref qself) = *maybe_qself {
 401                 visitor.visit_ty(&qself.ty);
 402             }
 403             visitor.visit_path(path, typ.id);
 404         }
 405         TyObjectSum(ref ty, ref bounds) => {
 406             visitor.visit_ty(ty);
 407             walk_list!(visitor, visit_ty_param_bound, bounds);
 408         }
 409         TyFixedLengthVec(ref ty, ref expression) => {
 410             visitor.visit_ty(ty);
 411             visitor.visit_expr(expression)
 412         }
 413         TyPolyTraitRef(ref bounds) => {
 414             walk_list!(visitor, visit_ty_param_bound, bounds);
 415         }
 416         TyTypeof(ref expression) => {
 417             visitor.visit_expr(expression)
 418         }
 419         TyInfer => {}
 420     }
 421 }
 422
 423 pub fn walk_path<'v, V: Visitor<'v>>(visitor: &mut V, path: &'v Path) {
 424     for segment in &path.segments {
 425         visitor.visit_path_segment(path.span, segment);
 426     }
 427 }
 428
 429 pub fn walk_path_list_item<'v, V: Visitor<'v>>(visitor: &mut V,
 430                                                prefix: &'v Path,
 431                                                item: &'v PathListItem) {
 432     for segment in &prefix.segments {
 433         visitor.visit_path_segment(prefix.span, segment);
 434     }
 435
 436     walk_opt_name(visitor, item.span, item.node.name());
 437     walk_opt_name(visitor, item.span, item.node.rename());
 438 }
 439
 440 pub fn walk_path_segment<'v, V: Visitor<'v>>(visitor: &mut V,
 441                                              path_span: Span,
 442                                              segment: &'v PathSegment) {
 443     visitor.visit_ident(path_span, segment.identifier);
 444     visitor.visit_path_parameters(path_span, &segment.parameters);
 445 }
 446
 447 pub fn walk_path_parameters<'v, V: Visitor<'v>>(visitor: &mut V,
 448                                                 _path_span: Span,
 449                                                 path_parameters: &'v PathParameters) {
 450     match *path_parameters {
 451         AngleBracketedParameters(ref data) => {
 452             walk_list!(visitor, visit_ty, &data.types);
 453             walk_list!(visitor, visit_lifetime, &data.lifetimes);
 454             walk_list!(visitor, visit_assoc_type_binding, &data.bindings);
 455         }
 456         ParenthesizedParameters(ref data) => {
 457             walk_list!(visitor, visit_ty, &data.inputs);
 458             walk_list!(visitor, visit_ty, &data.output);
 459         }
 460     }
 461 }
 462
 463 pub fn walk_assoc_type_binding<'v, V: Visitor<'v>>(visitor: &mut V,
 464                                                    type_binding: &'v TypeBinding) {
 465     visitor.visit_name(type_binding.span, type_binding.name);
 466     visitor.visit_ty(&type_binding.ty);
 467 }
 468
 469 pub fn walk_pat<'v, V: Visitor<'v>>(visitor: &mut V, pattern: &'v Pat) {
 470     match pattern.node {
 471         PatKind::TupleStruct(ref path, ref opt_children) => {
 472             visitor.visit_path(path, pattern.id);
 473             if let Some(ref children) = *opt_children {
 474                 walk_list!(visitor, visit_pat, children);
 475             }
 476         }
 477         PatKind::Path(ref path) => {
 478             visitor.visit_path(path, pattern.id);
 479         }
 480         PatKind::QPath(ref qself, ref path) => {
 481             visitor.visit_ty(&qself.ty);
 482             visitor.visit_path(path, pattern.id)
 483         }
 484         PatKind::Struct(ref path, ref fields, _) => {
 485             visitor.visit_path(path, pattern.id);
 486             for field in fields {
 487                 visitor.visit_name(field.span, field.node.name);
 488                 visitor.visit_pat(&field.node.pat)
 489             }
 490         }
 491         PatKind::Tup(ref tuple_elements) => {
 492             walk_list!(visitor, visit_pat, tuple_elements);
 493         }
 494         PatKind::Box(ref subpattern) |
 495         PatKind::Ref(ref subpattern, _) => {
 496             visitor.visit_pat(subpattern)
 497         }
 498         PatKind::Ident(_, ref pth1, ref optional_subpattern) => {
 499             visitor.visit_ident(pth1.span, pth1.node);
 500             walk_list!(visitor, visit_pat, optional_subpattern);
 501         }
 502         PatKind::Lit(ref expression) => visitor.visit_expr(expression),
 503         PatKind::Range(ref lower_bound, ref upper_bound) => {
 504             visitor.visit_expr(lower_bound);
 505             visitor.visit_expr(upper_bound)
 506         }
 507         PatKind::Wild => (),
 508         PatKind::Vec(ref prepatterns, ref slice_pattern, ref postpatterns) => {
 509             walk_list!(visitor, visit_pat, prepatterns);
 510             walk_list!(visitor, visit_pat, slice_pattern);
 511             walk_list!(visitor, visit_pat, postpatterns);
 512         }
 513     }
 514 }
 515
 516 pub fn walk_foreign_item<'v, V: Visitor<'v>>(visitor: &mut V, foreign_item: &'v ForeignItem) {
 517     visitor.visit_name(foreign_item.span, foreign_item.name);
 518
 519     match foreign_item.node {
 520         ForeignItemFn(ref function_declaration, ref generics) => {
 521             walk_fn_decl(visitor, function_declaration);
 522             visitor.visit_generics(generics)
 523         }
 524         ForeignItemStatic(ref typ, _) => visitor.visit_ty(typ),
 525     }
 526
 527     walk_list!(visitor, visit_attribute, &foreign_item.attrs);
 528 }
 529
 530 pub fn walk_ty_param_bound<'v, V: Visitor<'v>>(visitor: &mut V, bound: &'v TyParamBound) {
 531     match *bound {
 532         TraitTyParamBound(ref typ, ref modifier) => {
 533             visitor.visit_poly_trait_ref(typ, modifier);
 534         }
 535         RegionTyParamBound(ref lifetime) => {
 536             visitor.visit_lifetime(lifetime);
 537         }
 538     }
 539 }
 540
 541 pub fn walk_generics<'v, V: Visitor<'v>>(visitor: &mut V, generics: &'v Generics) {
 542     for param in &generics.ty_params {
 543         visitor.visit_name(param.span, param.name);
 544         walk_list!(visitor, visit_ty_param_bound, &param.bounds);
 545         walk_list!(visitor, visit_ty, &param.default);
 546     }
 547     walk_list!(visitor, visit_lifetime_def, &generics.lifetimes);
 548     for predicate in &generics.where_clause.predicates {
 549         match predicate {
 550             &WherePredicate::BoundPredicate(WhereBoundPredicate{ref bounded_ty,
 551                                                                           ref bounds,
 552                                                                           ref bound_lifetimes,
 553                                                                           ..}) => {
 554                 visitor.visit_ty(bounded_ty);
 555                 walk_list!(visitor, visit_ty_param_bound, bounds);
 556                 walk_list!(visitor, visit_lifetime_def, bound_lifetimes);
 557             }
 558             &WherePredicate::RegionPredicate(WhereRegionPredicate{ref lifetime,
 559                                                                             ref bounds,
 560                                                                             ..}) => {
 561                 visitor.visit_lifetime(lifetime);
 562                 walk_list!(visitor, visit_lifetime, bounds);
 563             }
 564             &WherePredicate::EqPredicate(WhereEqPredicate{id,
 565                                                                     ref path,
 566                                                                     ref ty,
 567                                                                     ..}) => {
 568                 visitor.visit_path(path, id);
 569                 visitor.visit_ty(ty);
 570             }
 571         }
 572     }
 573 }
 574
 575 pub fn walk_fn_ret_ty<'v, V: Visitor<'v>>(visitor: &mut V, ret_ty: &'v FunctionRetTy) {
 576     if let Return(ref output_ty) = *ret_ty {
 577         visitor.visit_ty(output_ty)
 578     }
 579 }
 580
 581 pub fn walk_fn_decl<'v, V: Visitor<'v>>(visitor: &mut V, function_declaration: &'v FnDecl) {
 582     for argument in &function_declaration.inputs {
 583         visitor.visit_pat(&argument.pat);
 584         visitor.visit_ty(&argument.ty)
 585     }
 586     walk_fn_ret_ty(visitor, &function_declaration.output)
 587 }
 588
 589 pub fn walk_fn_decl_nopat<'v, V: Visitor<'v>>(visitor: &mut V, function_declaration: &'v FnDecl) {
 590     for argument in &function_declaration.inputs {
 591         visitor.visit_ty(&argument.ty)
 592     }
 593     walk_fn_ret_ty(visitor, &function_declaration.output)
 594 }
 595
 596 pub fn walk_fn_kind<'v, V: Visitor<'v>>(visitor: &mut V, function_kind: FnKind<'v>) {
 597     match function_kind {
 598         FnKind::ItemFn(_, generics, _, _, _, _) => {
 599             visitor.visit_generics(generics);
 600         }
 601         FnKind::Method(_, sig, _) => {
 602             visitor.visit_generics(&sig.generics);
 603             visitor.visit_explicit_self(&sig.explicit_self);
 604         }
 605         FnKind::Closure => {}
 606     }
 607 }
 608
 609 pub fn walk_fn<'v, V: Visitor<'v>>(visitor: &mut V,
 610                                    function_kind: FnKind<'v>,
 611                                    function_declaration: &'v FnDecl,
 612                                    function_body: &'v Block,
 613                                    _span: Span) {
 614     walk_fn_decl(visitor, function_declaration);
 615     walk_fn_kind(visitor, function_kind);
 616     visitor.visit_block(function_body)
 617 }
 618
 619 pub fn walk_trait_item<'v, V: Visitor<'v>>(visitor: &mut V, trait_item: &'v TraitItem) {
 620     visitor.visit_name(trait_item.span, trait_item.name);
 621     walk_list!(visitor, visit_attribute, &trait_item.attrs);
 622     match trait_item.node {
 623         ConstTraitItem(ref ty, ref default) => {
 624             visitor.visit_ty(ty);
 625             walk_list!(visitor, visit_expr, default);
 626         }
 627         MethodTraitItem(ref sig, None) => {
 628             visitor.visit_explicit_self(&sig.explicit_self);
 629             visitor.visit_generics(&sig.generics);
 630             walk_fn_decl(visitor, &sig.decl);
 631         }
 632         MethodTraitItem(ref sig, Some(ref body)) => {
 633             visitor.visit_fn(FnKind::Method(trait_item.name, sig, None),
 634                              &sig.decl,
 635                              body,
 636                              trait_item.span,
 637                              trait_item.id);
 638         }
 639         TypeTraitItem(ref bounds, ref default) => {
 640             walk_list!(visitor, visit_ty_param_bound, bounds);
 641             walk_list!(visitor, visit_ty, default);
 642         }
 643     }
 644 }
 645
 646 pub fn walk_impl_item<'v, V: Visitor<'v>>(visitor: &mut V, impl_item: &'v ImplItem) {
 647     visitor.visit_name(impl_item.span, impl_item.name);
 648     walk_list!(visitor, visit_attribute, &impl_item.attrs);
 649     match impl_item.node {
 650         ImplItemKind::Const(ref ty, ref expr) => {
 651             visitor.visit_ty(ty);
 652             visitor.visit_expr(expr);
 653         }
 654         ImplItemKind::Method(ref sig, ref body) => {
 655             visitor.visit_fn(FnKind::Method(impl_item.name, sig, Some(impl_item.vis)),
 656                              &sig.decl,
 657                              body,
 658                              impl_item.span,
 659                              impl_item.id);
 660         }
 661         ImplItemKind::Type(ref ty) => {
 662             visitor.visit_ty(ty);
 663         }
 664     }
 665 }
 666
 667 pub fn walk_struct_def<'v, V: Visitor<'v>>(visitor: &mut V, struct_definition: &'v VariantData) {
 668     walk_list!(visitor, visit_struct_field, struct_definition.fields());
 669 }
 670
 671 pub fn walk_struct_field<'v, V: Visitor<'v>>(visitor: &mut V, struct_field: &'v StructField) {
 672     visitor.visit_name(struct_field.span, struct_field.name);
 673     visitor.visit_ty(&struct_field.ty);
 674     walk_list!(visitor, visit_attribute, &struct_field.attrs);
 675 }
 676
 677 pub fn walk_block<'v, V: Visitor<'v>>(visitor: &mut V, block: &'v Block) {
 678     walk_list!(visitor, visit_stmt, &block.stmts);
 679     walk_list!(visitor, visit_expr, &block.expr);
 680 }
 681
 682 pub fn walk_stmt<'v, V: Visitor<'v>>(visitor: &mut V, statement: &'v Stmt) {
 683     match statement.node {
 684         StmtDecl(ref declaration, _) => visitor.visit_decl(declaration),
 685         StmtExpr(ref expression, _) | StmtSemi(ref expression, _) => {
 686             visitor.visit_expr(expression)
 687         }
 688     }
 689 }
 690
 691 pub fn walk_decl<'v, V: Visitor<'v>>(visitor: &mut V, declaration: &'v Decl) {
 692     match declaration.node {
 693         DeclLocal(ref local) => visitor.visit_local(local),
 694         DeclItem(item) => visitor.visit_nested_item(item),
 695     }
 696 }
 697
 698 pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr) {
 699     match expression.node {
 700         ExprBox(ref subexpression) => {
 701             visitor.visit_expr(subexpression)
 702         }
 703         ExprVec(ref subexpressions) => {
 704             walk_list!(visitor, visit_expr, subexpressions);
 705         }
 706         ExprRepeat(ref element, ref count) => {
 707             visitor.visit_expr(element);
 708             visitor.visit_expr(count)
 709         }
 710         ExprStruct(ref path, ref fields, ref optional_base) => {
 711             visitor.visit_path(path, expression.id);
 712             for field in fields {
 713                 visitor.visit_name(field.name.span, field.name.node);
 714                 visitor.visit_expr(&field.expr)
 715             }
 716             walk_list!(visitor, visit_expr, optional_base);
 717         }
 718         ExprTup(ref subexpressions) => {
 719             walk_list!(visitor, visit_expr, subexpressions);
 720         }
 721         ExprCall(ref callee_expression, ref arguments) => {
 722             walk_list!(visitor, visit_expr, arguments);
 723             visitor.visit_expr(callee_expression)
 724         }
 725         ExprMethodCall(ref name, ref types, ref arguments) => {
 726             visitor.visit_name(name.span, name.node);
 727             walk_list!(visitor, visit_expr, arguments);
 728             walk_list!(visitor, visit_ty, types);
 729         }
 730         ExprBinary(_, ref left_expression, ref right_expression) => {
 731             visitor.visit_expr(left_expression);
 732             visitor.visit_expr(right_expression)
 733         }
 734         ExprAddrOf(_, ref subexpression) | ExprUnary(_, ref subexpression) => {
 735             visitor.visit_expr(subexpression)
 736         }
 737         ExprLit(_) => {}
 738         ExprCast(ref subexpression, ref typ) | ExprType(ref subexpression, ref typ) => {
 739             visitor.visit_expr(subexpression);
 740             visitor.visit_ty(typ)
 741         }
 742         ExprIf(ref head_expression, ref if_block, ref optional_else) => {
 743             visitor.visit_expr(head_expression);
 744             visitor.visit_block(if_block);
 745             walk_list!(visitor, visit_expr, optional_else);
 746         }
 747         ExprWhile(ref subexpression, ref block, opt_ident) => {
 748             visitor.visit_expr(subexpression);
 749             visitor.visit_block(block);
 750             walk_opt_ident(visitor, expression.span, opt_ident)
 751         }
 752         ExprLoop(ref block, opt_ident) => {
 753             visitor.visit_block(block);
 754             walk_opt_ident(visitor, expression.span, opt_ident)
 755         }
 756         ExprMatch(ref subexpression, ref arms, _) => {
 757             visitor.visit_expr(subexpression);
 758             walk_list!(visitor, visit_arm, arms);
 759         }
 760         ExprClosure(_, ref function_declaration, ref body) => {
 761             visitor.visit_fn(FnKind::Closure,
 762                              function_declaration,
 763                              body,
 764                              expression.span,
 765                              expression.id)
 766         }
 767         ExprBlock(ref block) => visitor.visit_block(block),
 768         ExprAssign(ref left_hand_expression, ref right_hand_expression) => {
 769             visitor.visit_expr(right_hand_expression);
 770             visitor.visit_expr(left_hand_expression)
 771         }
 772         ExprAssignOp(_, ref left_expression, ref right_expression) => {
 773             visitor.visit_expr(right_expression);
 774             visitor.visit_expr(left_expression)
 775         }
 776         ExprField(ref subexpression, ref name) => {
 777             visitor.visit_expr(subexpression);
 778             visitor.visit_name(name.span, name.node);
 779         }
 780         ExprTupField(ref subexpression, _) => {
 781             visitor.visit_expr(subexpression);
 782         }
 783         ExprIndex(ref main_expression, ref index_expression) => {
 784             visitor.visit_expr(main_expression);
 785             visitor.visit_expr(index_expression)
 786         }
 787         ExprPath(ref maybe_qself, ref path) => {
 788             if let Some(ref qself) = *maybe_qself {
 789                 visitor.visit_ty(&qself.ty);
 790             }
 791             visitor.visit_path(path, expression.id)
 792         }
 793         ExprBreak(ref opt_sp_ident) | ExprAgain(ref opt_sp_ident) => {
 794             for sp_ident in opt_sp_ident {
 795                 visitor.visit_ident(sp_ident.span, sp_ident.node);
 796             }
 797         }
 798         ExprRet(ref optional_expression) => {
 799             walk_list!(visitor, visit_expr, optional_expression);
 800         }
 801         ExprInlineAsm(ref ia) => {
 802             for &(_, ref input) in &ia.inputs {
 803                 visitor.visit_expr(&input)
 804             }
 805             for output in &ia.outputs {
 806                 visitor.visit_expr(&output.expr)
 807             }
 808         }
 809     }
 810
 811     visitor.visit_expr_post(expression)
 812 }
 813
 814 pub fn walk_arm<'v, V: Visitor<'v>>(visitor: &mut V, arm: &'v Arm) {
 815     walk_list!(visitor, visit_pat, &arm.pats);
 816     walk_list!(visitor, visit_expr, &arm.guard);
 817     visitor.visit_expr(&arm.body);
 818     walk_list!(visitor, visit_attribute, &arm.attrs);
 819 }