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