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