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