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