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 syntax_pos::Span;
  29 use codemap::Spanned;
  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, Spanned<Constness>, Abi, &'a Visibility),
  35
  36     /// fn foo(&self)
  37     Method(Ident, &'a MethodSig, Option<&'a 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: 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: &Mod, _s: Span, _n: NodeId) { walk_mod(self, m) }
  60     fn visit_foreign_item(&mut self, i: &ForeignItem) { walk_foreign_item(self, i) }
  61     fn visit_item(&mut self, i: &Item) { walk_item(self, i) }
  62     fn visit_local(&mut self, l: &Local) { walk_local(self, l) }
  63     fn visit_block(&mut self, b: &Block) { walk_block(self, b) }
  64     fn visit_stmt(&mut self, s: &Stmt) { walk_stmt(self, s) }
  65     fn visit_arm(&mut self, a: &Arm) { walk_arm(self, a) }
  66     fn visit_pat(&mut self, p: &Pat) { walk_pat(self, p) }
  67     fn visit_expr(&mut self, ex: &Expr) { walk_expr(self, ex) }
  68     fn visit_expr_post(&mut self, _ex: &Expr) { }
  69     fn visit_ty(&mut self, t: &Ty) { walk_ty(self, t) }
  70     fn visit_generics(&mut self, g: &Generics) { walk_generics(self, g) }
  71     fn visit_fn(&mut self, fk: FnKind, fd: &FnDecl, b: &Block, s: Span, _: NodeId) {
  72         walk_fn(self, fk, fd, b, s)
  73     }
  74     fn visit_trait_item(&mut self, ti: &TraitItem) { walk_trait_item(self, ti) }
  75     fn visit_impl_item(&mut self, ii: &ImplItem) { walk_impl_item(self, ii) }
  76     fn visit_trait_ref(&mut self, t: &TraitRef) { walk_trait_ref(self, t) }
  77     fn visit_ty_param_bound(&mut self, bounds: &TyParamBound) {
  78         walk_ty_param_bound(self, bounds)
  79     }
  80     fn visit_poly_trait_ref(&mut self, t: &PolyTraitRef, m: &TraitBoundModifier) {
  81         walk_poly_trait_ref(self, t, m)
  82     }
  83     fn visit_variant_data(&mut self, s: &VariantData, _: Ident,
  84                           _: &Generics, _: NodeId, _: Span) {
  85         walk_struct_def(self, s)
  86     }
  87     fn visit_struct_field(&mut self, s: &StructField) { walk_struct_field(self, s) }
  88     fn visit_enum_def(&mut self, enum_definition: &EnumDef,
  89                       generics: &Generics, item_id: NodeId, _: Span) {
  90         walk_enum_def(self, enum_definition, generics, item_id)
  91     }
  92     fn visit_variant(&mut self, v: &Variant, g: &Generics, item_id: NodeId) {
  93         walk_variant(self, v, g, item_id)
  94     }
  95     fn visit_lifetime(&mut self, lifetime: &Lifetime) {
  96         walk_lifetime(self, lifetime)
  97     }
  98     fn visit_lifetime_def(&mut self, lifetime: &LifetimeDef) {
  99         walk_lifetime_def(self, lifetime)
 100     }
 101     fn visit_mac(&mut self, _mac: &Mac) {
 102         panic!("visit_mac disabled by default");
 103         // NB: see note about macros above.
 104         // if you really want a visitor that
 105         // works on macros, use this
 106         // definition in your trait impl:
 107         // visit::walk_mac(self, _mac)
 108     }
 109     fn visit_path(&mut self, path: &Path, _id: NodeId) {
 110         walk_path(self, path)
 111     }
 112     fn visit_path_list_item(&mut self, prefix: &Path, item: &PathListItem) {
 113         walk_path_list_item(self, prefix, item)
 114     }
 115     fn visit_path_segment(&mut self, path_span: Span, path_segment: &PathSegment) {
 116         walk_path_segment(self, path_span, path_segment)
 117     }
 118     fn visit_path_parameters(&mut self, path_span: Span, path_parameters: &PathParameters) {
 119         walk_path_parameters(self, path_span, path_parameters)
 120     }
 121     fn visit_assoc_type_binding(&mut self, type_binding: &TypeBinding) {
 122         walk_assoc_type_binding(self, type_binding)
 123     }
 124     fn visit_attribute(&mut self, _attr: &Attribute) {}
 125     fn visit_macro_def(&mut self, macro_def: &MacroDef) {
 126         walk_macro_def(self, macro_def)
 127     }
 128     fn visit_vis(&mut self, vis: &Visibility) {
 129         walk_vis(self, vis)
 130     }
 131     fn visit_fn_ret_ty(&mut self, ret_ty: &FunctionRetTy) {
 132         walk_fn_ret_ty(self, ret_ty)
 133     }
 134 }
 135
 136 #[macro_export]
 137 macro_rules! walk_list {
 138     ($visitor: expr, $method: ident, $list: expr) => {
 139         for elem in $list {
 140             $visitor.$method(elem)
 141         }
 142     };
 143     ($visitor: expr, $method: ident, $list: expr, $($extra_args: expr),*) => {
 144         for elem in $list {
 145             $visitor.$method(elem, $($extra_args,)*)
 146         }
 147     }
 148 }
 149
 150 pub fn walk_opt_name<V: Visitor>(visitor: &mut V, span: Span, opt_name: Option<Name>) {
 151     if let Some(name) = opt_name {
 152         visitor.visit_name(span, name);
 153     }
 154 }
 155
 156 pub fn walk_opt_ident<V: Visitor>(visitor: &mut V, span: Span, opt_ident: Option<Ident>) {
 157     if let Some(ident) = opt_ident {
 158         visitor.visit_ident(span, ident);
 159     }
 160 }
 161
 162 pub fn walk_opt_sp_ident<V: Visitor>(visitor: &mut V, opt_sp_ident: &Option<Spanned<Ident>>) {
 163     if let Some(ref sp_ident) = *opt_sp_ident {
 164         visitor.visit_ident(sp_ident.span, sp_ident.node);
 165     }
 166 }
 167
 168 pub fn walk_ident<V: Visitor>(visitor: &mut V, span: Span, ident: Ident) {
 169     visitor.visit_name(span, ident.name);
 170 }
 171
 172 pub fn walk_crate<V: Visitor>(visitor: &mut V, krate: &Crate) {
 173     visitor.visit_mod(&krate.module, krate.span, CRATE_NODE_ID);
 174     walk_list!(visitor, visit_attribute, &krate.attrs);
 175     walk_list!(visitor, visit_macro_def, &krate.exported_macros);
 176 }
 177
 178 pub fn walk_macro_def<V: Visitor>(visitor: &mut V, macro_def: &MacroDef) {
 179     visitor.visit_ident(macro_def.span, macro_def.ident);
 180     walk_opt_ident(visitor, macro_def.span, macro_def.imported_from);
 181     walk_list!(visitor, visit_attribute, &macro_def.attrs);
 182 }
 183
 184 pub fn walk_mod<V: Visitor>(visitor: &mut V, module: &Mod) {
 185     walk_list!(visitor, visit_item, &module.items);
 186 }
 187
 188 pub fn walk_local<V: Visitor>(visitor: &mut V, local: &Local) {
 189     for attr in local.attrs.iter() {
 190         visitor.visit_attribute(attr);
 191     }
 192     visitor.visit_pat(&local.pat);
 193     walk_list!(visitor, visit_ty, &local.ty);
 194     walk_list!(visitor, visit_expr, &local.init);
 195 }
 196
 197 pub fn walk_lifetime<V: Visitor>(visitor: &mut V, lifetime: &Lifetime) {
 198     visitor.visit_name(lifetime.span, lifetime.name);
 199 }
 200
 201 pub fn walk_lifetime_def<V: Visitor>(visitor: &mut V, lifetime_def: &LifetimeDef) {
 202     visitor.visit_lifetime(&lifetime_def.lifetime);
 203     walk_list!(visitor, visit_lifetime, &lifetime_def.bounds);
 204     walk_list!(visitor, visit_attribute, &*lifetime_def.attrs);
 205 }
 206
 207 pub fn walk_poly_trait_ref<V>(visitor: &mut V, trait_ref: &PolyTraitRef, _: &TraitBoundModifier)
 208     where V: Visitor,
 209 {
 210     walk_list!(visitor, visit_lifetime_def, &trait_ref.bound_lifetimes);
 211     visitor.visit_trait_ref(&trait_ref.trait_ref);
 212 }
 213
 214 pub fn walk_trait_ref<V: Visitor>(visitor: &mut V, trait_ref: &TraitRef) {
 215     visitor.visit_path(&trait_ref.path, trait_ref.ref_id)
 216 }
 217
 218 pub fn walk_item<V: Visitor>(visitor: &mut V, item: &Item) {
 219     visitor.visit_vis(&item.vis);
 220     visitor.visit_ident(item.span, item.ident);
 221     match item.node {
 222         ItemKind::ExternCrate(opt_name) => {
 223             walk_opt_name(visitor, item.span, opt_name)
 224         }
 225         ItemKind::Use(ref vp) => {
 226             match vp.node {
 227                 ViewPathSimple(ident, ref path) => {
 228                     visitor.visit_ident(vp.span, ident);
 229                     visitor.visit_path(path, item.id);
 230                 }
 231                 ViewPathGlob(ref path) => {
 232                     visitor.visit_path(path, item.id);
 233                 }
 234                 ViewPathList(ref prefix, ref list) => {
 235                     visitor.visit_path(prefix, item.id);
 236                     for item in list {
 237                         visitor.visit_path_list_item(prefix, item)
 238                     }
 239                 }
 240             }
 241         }
 242         ItemKind::Static(ref typ, _, ref expr) |
 243         ItemKind::Const(ref typ, ref expr) => {
 244             visitor.visit_ty(typ);
 245             visitor.visit_expr(expr);
 246         }
 247         ItemKind::Fn(ref declaration, unsafety, constness, abi, ref generics, ref body) => {
 248             visitor.visit_fn(FnKind::ItemFn(item.ident, generics, unsafety,
 249                                             constness, abi, &item.vis),
 250                              declaration,
 251                              body,
 252                              item.span,
 253                              item.id)
 254         }
 255         ItemKind::Mod(ref module) => {
 256             visitor.visit_mod(module, item.span, item.id)
 257         }
 258         ItemKind::ForeignMod(ref foreign_module) => {
 259             walk_list!(visitor, visit_foreign_item, &foreign_module.items);
 260         }
 261         ItemKind::Ty(ref typ, ref type_parameters) => {
 262             visitor.visit_ty(typ);
 263             visitor.visit_generics(type_parameters)
 264         }
 265         ItemKind::Enum(ref enum_definition, ref type_parameters) => {
 266             visitor.visit_generics(type_parameters);
 267             visitor.visit_enum_def(enum_definition, type_parameters, item.id, item.span)
 268         }
 269         ItemKind::DefaultImpl(_, ref trait_ref) => {
 270             visitor.visit_trait_ref(trait_ref)
 271         }
 272         ItemKind::Impl(_, _,
 273                  ref type_parameters,
 274                  ref opt_trait_reference,
 275                  ref typ,
 276                  ref impl_items) => {
 277             visitor.visit_generics(type_parameters);
 278             walk_list!(visitor, visit_trait_ref, opt_trait_reference);
 279             visitor.visit_ty(typ);
 280             walk_list!(visitor, visit_impl_item, impl_items);
 281         }
 282         ItemKind::Struct(ref struct_definition, ref generics) |
 283         ItemKind::Union(ref struct_definition, ref generics) => {
 284             visitor.visit_generics(generics);
 285             visitor.visit_variant_data(struct_definition, item.ident,
 286                                      generics, item.id, item.span);
 287         }
 288         ItemKind::Trait(_, ref generics, ref bounds, ref methods) => {
 289             visitor.visit_generics(generics);
 290             walk_list!(visitor, visit_ty_param_bound, bounds);
 291             walk_list!(visitor, visit_trait_item, methods);
 292         }
 293         ItemKind::Mac(ref mac) => visitor.visit_mac(mac),
 294     }
 295     walk_list!(visitor, visit_attribute, &item.attrs);
 296 }
 297
 298 pub fn walk_enum_def<V: Visitor>(visitor: &mut V,
 299                                  enum_definition: &EnumDef,
 300                                  generics: &Generics,
 301                                  item_id: NodeId) {
 302     walk_list!(visitor, visit_variant, &enum_definition.variants, generics, item_id);
 303 }
 304
 305 pub fn walk_variant<V>(visitor: &mut V, variant: &Variant, generics: &Generics, item_id: NodeId)
 306     where V: Visitor,
 307 {
 308     visitor.visit_ident(variant.span, variant.node.name);
 309     visitor.visit_variant_data(&variant.node.data, variant.node.name,
 310                              generics, item_id, variant.span);
 311     walk_list!(visitor, visit_expr, &variant.node.disr_expr);
 312     walk_list!(visitor, visit_attribute, &variant.node.attrs);
 313 }
 314
 315 pub fn walk_ty<V: Visitor>(visitor: &mut V, typ: &Ty) {
 316     match typ.node {
 317         TyKind::Slice(ref ty) | TyKind::Paren(ref ty) => {
 318             visitor.visit_ty(ty)
 319         }
 320         TyKind::Ptr(ref mutable_type) => {
 321             visitor.visit_ty(&mutable_type.ty)
 322         }
 323         TyKind::Rptr(ref opt_lifetime, ref mutable_type) => {
 324             walk_list!(visitor, visit_lifetime, opt_lifetime);
 325             visitor.visit_ty(&mutable_type.ty)
 326         }
 327         TyKind::Never => {},
 328         TyKind::Tup(ref tuple_element_types) => {
 329             walk_list!(visitor, visit_ty, tuple_element_types);
 330         }
 331         TyKind::BareFn(ref function_declaration) => {
 332             walk_fn_decl(visitor, &function_declaration.decl);
 333             walk_list!(visitor, visit_lifetime_def, &function_declaration.lifetimes);
 334         }
 335         TyKind::Path(ref maybe_qself, ref path) => {
 336             if let Some(ref qself) = *maybe_qself {
 337                 visitor.visit_ty(&qself.ty);
 338             }
 339             visitor.visit_path(path, typ.id);
 340         }
 341         TyKind::ObjectSum(ref ty, ref bounds) => {
 342             visitor.visit_ty(ty);
 343             walk_list!(visitor, visit_ty_param_bound, bounds);
 344         }
 345         TyKind::Array(ref ty, ref expression) => {
 346             visitor.visit_ty(ty);
 347             visitor.visit_expr(expression)
 348         }
 349         TyKind::PolyTraitRef(ref bounds) => {
 350             walk_list!(visitor, visit_ty_param_bound, bounds);
 351         }
 352         TyKind::ImplTrait(ref bounds) => {
 353             walk_list!(visitor, visit_ty_param_bound, bounds);
 354         }
 355         TyKind::Typeof(ref expression) => {
 356             visitor.visit_expr(expression)
 357         }
 358         TyKind::Infer | TyKind::ImplicitSelf => {}
 359         TyKind::Mac(ref mac) => {
 360             visitor.visit_mac(mac)
 361         }
 362     }
 363 }
 364
 365 pub fn walk_path<V: Visitor>(visitor: &mut V, path: &Path) {
 366     for segment in &path.segments {
 367         visitor.visit_path_segment(path.span, segment);
 368     }
 369 }
 370
 371 pub fn walk_path_list_item<V: Visitor>(visitor: &mut V, _prefix: &Path, item: &PathListItem) {
 372     visitor.visit_ident(item.span, item.node.name);
 373     walk_opt_ident(visitor, item.span, item.node.rename);
 374 }
 375
 376 pub fn walk_path_segment<V: Visitor>(visitor: &mut V, path_span: Span, segment: &PathSegment) {
 377     visitor.visit_ident(path_span, segment.identifier);
 378     visitor.visit_path_parameters(path_span, &segment.parameters);
 379 }
 380
 381 pub fn walk_path_parameters<V>(visitor: &mut V, _path_span: Span, path_parameters: &PathParameters)
 382     where V: Visitor,
 383 {
 384     match *path_parameters {
 385         PathParameters::AngleBracketed(ref data) => {
 386             walk_list!(visitor, visit_ty, &data.types);
 387             walk_list!(visitor, visit_lifetime, &data.lifetimes);
 388             walk_list!(visitor, visit_assoc_type_binding, &data.bindings);
 389         }
 390         PathParameters::Parenthesized(ref data) => {
 391             walk_list!(visitor, visit_ty, &data.inputs);
 392             walk_list!(visitor, visit_ty, &data.output);
 393         }
 394     }
 395 }
 396
 397 pub fn walk_assoc_type_binding<V: Visitor>(visitor: &mut V, type_binding: &TypeBinding) {
 398     visitor.visit_ident(type_binding.span, type_binding.ident);
 399     visitor.visit_ty(&type_binding.ty);
 400 }
 401
 402 pub fn walk_pat<V: Visitor>(visitor: &mut V, pattern: &Pat) {
 403     match pattern.node {
 404         PatKind::TupleStruct(ref path, ref children, _) => {
 405             visitor.visit_path(path, pattern.id);
 406             walk_list!(visitor, visit_pat, children);
 407         }
 408         PatKind::Path(ref opt_qself, ref path) => {
 409             if let Some(ref qself) = *opt_qself {
 410                 visitor.visit_ty(&qself.ty);
 411             }
 412             visitor.visit_path(path, pattern.id)
 413         }
 414         PatKind::Struct(ref path, ref fields, _) => {
 415             visitor.visit_path(path, pattern.id);
 416             for field in fields {
 417                 visitor.visit_ident(field.span, field.node.ident);
 418                 visitor.visit_pat(&field.node.pat)
 419             }
 420         }
 421         PatKind::Tuple(ref tuple_elements, _) => {
 422             walk_list!(visitor, visit_pat, tuple_elements);
 423         }
 424         PatKind::Box(ref subpattern) |
 425         PatKind::Ref(ref subpattern, _) => {
 426             visitor.visit_pat(subpattern)
 427         }
 428         PatKind::Ident(_, ref pth1, ref optional_subpattern) => {
 429             visitor.visit_ident(pth1.span, pth1.node);
 430             walk_list!(visitor, visit_pat, optional_subpattern);
 431         }
 432         PatKind::Lit(ref expression) => visitor.visit_expr(expression),
 433         PatKind::Range(ref lower_bound, ref upper_bound) => {
 434             visitor.visit_expr(lower_bound);
 435             visitor.visit_expr(upper_bound)
 436         }
 437         PatKind::Wild => (),
 438         PatKind::Slice(ref prepatterns, ref slice_pattern, ref postpatterns) => {
 439             walk_list!(visitor, visit_pat, prepatterns);
 440             walk_list!(visitor, visit_pat, slice_pattern);
 441             walk_list!(visitor, visit_pat, postpatterns);
 442         }
 443         PatKind::Mac(ref mac) => visitor.visit_mac(mac),
 444     }
 445 }
 446
 447 pub fn walk_foreign_item<V: Visitor>(visitor: &mut V, foreign_item: &ForeignItem) {
 448     visitor.visit_vis(&foreign_item.vis);
 449     visitor.visit_ident(foreign_item.span, foreign_item.ident);
 450
 451     match foreign_item.node {
 452         ForeignItemKind::Fn(ref function_declaration, ref generics) => {
 453             walk_fn_decl(visitor, function_declaration);
 454             visitor.visit_generics(generics)
 455         }
 456         ForeignItemKind::Static(ref typ, _) => visitor.visit_ty(typ),
 457     }
 458
 459     walk_list!(visitor, visit_attribute, &foreign_item.attrs);
 460 }
 461
 462 pub fn walk_ty_param_bound<V: Visitor>(visitor: &mut V, bound: &TyParamBound) {
 463     match *bound {
 464         TraitTyParamBound(ref typ, ref modifier) => {
 465             visitor.visit_poly_trait_ref(typ, modifier);
 466         }
 467         RegionTyParamBound(ref lifetime) => {
 468             visitor.visit_lifetime(lifetime);
 469         }
 470     }
 471 }
 472
 473 pub fn walk_generics<V: Visitor>(visitor: &mut V, generics: &Generics) {
 474     for param in &generics.ty_params {
 475         visitor.visit_ident(param.span, param.ident);
 476         walk_list!(visitor, visit_ty_param_bound, &param.bounds);
 477         walk_list!(visitor, visit_ty, &param.default);
 478         walk_list!(visitor, visit_attribute, &*param.attrs);
 479     }
 480     walk_list!(visitor, visit_lifetime_def, &generics.lifetimes);
 481     for predicate in &generics.where_clause.predicates {
 482         match *predicate {
 483             WherePredicate::BoundPredicate(WhereBoundPredicate{ref bounded_ty,
 484                                                                ref bounds,
 485                                                                ref bound_lifetimes,
 486                                                                ..}) => {
 487                 visitor.visit_ty(bounded_ty);
 488                 walk_list!(visitor, visit_ty_param_bound, bounds);
 489                 walk_list!(visitor, visit_lifetime_def, bound_lifetimes);
 490             }
 491             WherePredicate::RegionPredicate(WhereRegionPredicate{ref lifetime,
 492                                                                  ref bounds,
 493                                                                  ..}) => {
 494                 visitor.visit_lifetime(lifetime);
 495                 walk_list!(visitor, visit_lifetime, bounds);
 496             }
 497             WherePredicate::EqPredicate(WhereEqPredicate{id,
 498                                                          ref path,
 499                                                          ref ty,
 500                                                          ..}) => {
 501                 visitor.visit_path(path, id);
 502                 visitor.visit_ty(ty);
 503             }
 504         }
 505     }
 506 }
 507
 508 pub fn walk_fn_ret_ty<V: Visitor>(visitor: &mut V, ret_ty: &FunctionRetTy) {
 509     if let FunctionRetTy::Ty(ref output_ty) = *ret_ty {
 510         visitor.visit_ty(output_ty)
 511     }
 512 }
 513
 514 pub fn walk_fn_decl<V: Visitor>(visitor: &mut V, function_declaration: &FnDecl) {
 515     for argument in &function_declaration.inputs {
 516         visitor.visit_pat(&argument.pat);
 517         visitor.visit_ty(&argument.ty)
 518     }
 519     visitor.visit_fn_ret_ty(&function_declaration.output)
 520 }
 521
 522 pub fn walk_fn_kind<V: Visitor>(visitor: &mut V, function_kind: FnKind) {
 523     match function_kind {
 524         FnKind::ItemFn(_, generics, _, _, _, _) => {
 525             visitor.visit_generics(generics);
 526         }
 527         FnKind::Method(_, ref sig, _) => {
 528             visitor.visit_generics(&sig.generics);
 529         }
 530         FnKind::Closure => {}
 531     }
 532 }
 533
 534 pub fn walk_fn<V>(visitor: &mut V, kind: FnKind, declaration: &FnDecl, body: &Block, _span: Span)
 535     where V: Visitor,
 536 {
 537     walk_fn_kind(visitor, kind);
 538     walk_fn_decl(visitor, declaration);
 539     visitor.visit_block(body)
 540 }
 541
 542 pub fn walk_trait_item<V: Visitor>(visitor: &mut V, trait_item: &TraitItem) {
 543     visitor.visit_ident(trait_item.span, trait_item.ident);
 544     walk_list!(visitor, visit_attribute, &trait_item.attrs);
 545     match trait_item.node {
 546         TraitItemKind::Const(ref ty, ref default) => {
 547             visitor.visit_ty(ty);
 548             walk_list!(visitor, visit_expr, default);
 549         }
 550         TraitItemKind::Method(ref sig, None) => {
 551             visitor.visit_generics(&sig.generics);
 552             walk_fn_decl(visitor, &sig.decl);
 553         }
 554         TraitItemKind::Method(ref sig, Some(ref body)) => {
 555             visitor.visit_fn(FnKind::Method(trait_item.ident, sig, None), &sig.decl,
 556                              body, trait_item.span, trait_item.id);
 557         }
 558         TraitItemKind::Type(ref bounds, ref default) => {
 559             walk_list!(visitor, visit_ty_param_bound, bounds);
 560             walk_list!(visitor, visit_ty, default);
 561         }
 562         TraitItemKind::Macro(ref mac) => {
 563             visitor.visit_mac(mac);
 564         }
 565     }
 566 }
 567
 568 pub fn walk_impl_item<V: Visitor>(visitor: &mut V, impl_item: &ImplItem) {
 569     visitor.visit_vis(&impl_item.vis);
 570     visitor.visit_ident(impl_item.span, impl_item.ident);
 571     walk_list!(visitor, visit_attribute, &impl_item.attrs);
 572     match impl_item.node {
 573         ImplItemKind::Const(ref ty, ref expr) => {
 574             visitor.visit_ty(ty);
 575             visitor.visit_expr(expr);
 576         }
 577         ImplItemKind::Method(ref sig, ref body) => {
 578             visitor.visit_fn(FnKind::Method(impl_item.ident, sig, Some(&impl_item.vis)), &sig.decl,
 579                              body, impl_item.span, impl_item.id);
 580         }
 581         ImplItemKind::Type(ref ty) => {
 582             visitor.visit_ty(ty);
 583         }
 584         ImplItemKind::Macro(ref mac) => {
 585             visitor.visit_mac(mac);
 586         }
 587     }
 588 }
 589
 590 pub fn walk_struct_def<V: Visitor>(visitor: &mut V, struct_definition: &VariantData) {
 591     walk_list!(visitor, visit_struct_field, struct_definition.fields());
 592 }
 593
 594 pub fn walk_struct_field<V: Visitor>(visitor: &mut V, struct_field: &StructField) {
 595     visitor.visit_vis(&struct_field.vis);
 596     walk_opt_ident(visitor, struct_field.span, struct_field.ident);
 597     visitor.visit_ty(&struct_field.ty);
 598     walk_list!(visitor, visit_attribute, &struct_field.attrs);
 599 }
 600
 601 pub fn walk_block<V: Visitor>(visitor: &mut V, block: &Block) {
 602     walk_list!(visitor, visit_stmt, &block.stmts);
 603 }
 604
 605 pub fn walk_stmt<V: Visitor>(visitor: &mut V, statement: &Stmt) {
 606     match statement.node {
 607         StmtKind::Local(ref local) => visitor.visit_local(local),
 608         StmtKind::Item(ref item) => visitor.visit_item(item),
 609         StmtKind::Expr(ref expression) | StmtKind::Semi(ref expression) => {
 610             visitor.visit_expr(expression)
 611         }
 612         StmtKind::Mac(ref mac) => {
 613             let (ref mac, _, ref attrs) = **mac;
 614             visitor.visit_mac(mac);
 615             for attr in attrs.iter() {
 616                 visitor.visit_attribute(attr);
 617             }
 618         }
 619     }
 620 }
 621
 622 pub fn walk_mac<V: Visitor>(_: &mut V, _: &Mac) {
 623     // Empty!
 624 }
 625
 626 pub fn walk_expr<V: Visitor>(visitor: &mut V, expression: &Expr) {
 627     for attr in expression.attrs.iter() {
 628         visitor.visit_attribute(attr);
 629     }
 630     match expression.node {
 631         ExprKind::Box(ref subexpression) => {
 632             visitor.visit_expr(subexpression)
 633         }
 634         ExprKind::InPlace(ref place, ref subexpression) => {
 635             visitor.visit_expr(place);
 636             visitor.visit_expr(subexpression)
 637         }
 638         ExprKind::Vec(ref subexpressions) => {
 639             walk_list!(visitor, visit_expr, subexpressions);
 640         }
 641         ExprKind::Repeat(ref element, ref count) => {
 642             visitor.visit_expr(element);
 643             visitor.visit_expr(count)
 644         }
 645         ExprKind::Struct(ref path, ref fields, ref optional_base) => {
 646             visitor.visit_path(path, expression.id);
 647             for field in fields {
 648                 visitor.visit_ident(field.ident.span, field.ident.node);
 649                 visitor.visit_expr(&field.expr)
 650             }
 651             walk_list!(visitor, visit_expr, optional_base);
 652         }
 653         ExprKind::Tup(ref subexpressions) => {
 654             walk_list!(visitor, visit_expr, subexpressions);
 655         }
 656         ExprKind::Call(ref callee_expression, ref arguments) => {
 657             visitor.visit_expr(callee_expression);
 658             walk_list!(visitor, visit_expr, arguments);
 659         }
 660         ExprKind::MethodCall(ref ident, ref types, ref arguments) => {
 661             visitor.visit_ident(ident.span, ident.node);
 662             walk_list!(visitor, visit_ty, types);
 663             walk_list!(visitor, visit_expr, arguments);
 664         }
 665         ExprKind::Binary(_, ref left_expression, ref right_expression) => {
 666             visitor.visit_expr(left_expression);
 667             visitor.visit_expr(right_expression)
 668         }
 669         ExprKind::AddrOf(_, ref subexpression) | ExprKind::Unary(_, ref subexpression) => {
 670             visitor.visit_expr(subexpression)
 671         }
 672         ExprKind::Lit(_) => {}
 673         ExprKind::Cast(ref subexpression, ref typ) | ExprKind::Type(ref subexpression, ref typ) => {
 674             visitor.visit_expr(subexpression);
 675             visitor.visit_ty(typ)
 676         }
 677         ExprKind::If(ref head_expression, ref if_block, ref optional_else) => {
 678             visitor.visit_expr(head_expression);
 679             visitor.visit_block(if_block);
 680             walk_list!(visitor, visit_expr, optional_else);
 681         }
 682         ExprKind::While(ref subexpression, ref block, ref opt_sp_ident) => {
 683             visitor.visit_expr(subexpression);
 684             visitor.visit_block(block);
 685             walk_opt_sp_ident(visitor, opt_sp_ident);
 686         }
 687         ExprKind::IfLet(ref pattern, ref subexpression, ref if_block, ref optional_else) => {
 688             visitor.visit_pat(pattern);
 689             visitor.visit_expr(subexpression);
 690             visitor.visit_block(if_block);
 691             walk_list!(visitor, visit_expr, optional_else);
 692         }
 693         ExprKind::WhileLet(ref pattern, ref subexpression, ref block, ref opt_sp_ident) => {
 694             visitor.visit_pat(pattern);
 695             visitor.visit_expr(subexpression);
 696             visitor.visit_block(block);
 697             walk_opt_sp_ident(visitor, opt_sp_ident);
 698         }
 699         ExprKind::ForLoop(ref pattern, ref subexpression, ref block, ref opt_sp_ident) => {
 700             visitor.visit_pat(pattern);
 701             visitor.visit_expr(subexpression);
 702             visitor.visit_block(block);
 703             walk_opt_sp_ident(visitor, opt_sp_ident);
 704         }
 705         ExprKind::Loop(ref block, ref opt_sp_ident) => {
 706             visitor.visit_block(block);
 707             walk_opt_sp_ident(visitor, opt_sp_ident);
 708         }
 709         ExprKind::Match(ref subexpression, ref arms) => {
 710             visitor.visit_expr(subexpression);
 711             walk_list!(visitor, visit_arm, arms);
 712         }
 713         ExprKind::Closure(_, ref function_declaration, ref body, _decl_span) => {
 714             visitor.visit_fn(FnKind::Closure,
 715                              function_declaration,
 716                              body,
 717                              expression.span,
 718                              expression.id)
 719         }
 720         ExprKind::Block(ref block) => visitor.visit_block(block),
 721         ExprKind::Assign(ref left_hand_expression, ref right_hand_expression) => {
 722             visitor.visit_expr(left_hand_expression);
 723             visitor.visit_expr(right_hand_expression);
 724         }
 725         ExprKind::AssignOp(_, ref left_expression, ref right_expression) => {
 726             visitor.visit_expr(left_expression);
 727             visitor.visit_expr(right_expression);
 728         }
 729         ExprKind::Field(ref subexpression, ref ident) => {
 730             visitor.visit_expr(subexpression);
 731             visitor.visit_ident(ident.span, ident.node);
 732         }
 733         ExprKind::TupField(ref subexpression, _) => {
 734             visitor.visit_expr(subexpression);
 735         }
 736         ExprKind::Index(ref main_expression, ref index_expression) => {
 737             visitor.visit_expr(main_expression);
 738             visitor.visit_expr(index_expression)
 739         }
 740         ExprKind::Range(ref start, ref end, _) => {
 741             walk_list!(visitor, visit_expr, start);
 742             walk_list!(visitor, visit_expr, end);
 743         }
 744         ExprKind::Path(ref maybe_qself, ref path) => {
 745             if let Some(ref qself) = *maybe_qself {
 746                 visitor.visit_ty(&qself.ty);
 747             }
 748             visitor.visit_path(path, expression.id)
 749         }
 750         ExprKind::Break(ref opt_sp_ident) | ExprKind::Continue(ref opt_sp_ident) => {
 751             walk_opt_sp_ident(visitor, opt_sp_ident);
 752         }
 753         ExprKind::Ret(ref optional_expression) => {
 754             walk_list!(visitor, visit_expr, optional_expression);
 755         }
 756         ExprKind::Mac(ref mac) => visitor.visit_mac(mac),
 757         ExprKind::Paren(ref subexpression) => {
 758             visitor.visit_expr(subexpression)
 759         }
 760         ExprKind::InlineAsm(ref ia) => {
 761             for &(_, ref input) in &ia.inputs {
 762                 visitor.visit_expr(&input)
 763             }
 764             for output in &ia.outputs {
 765                 visitor.visit_expr(&output.expr)
 766             }
 767         }
 768         ExprKind::Try(ref subexpression) => {
 769             visitor.visit_expr(subexpression)
 770         }
 771     }
 772
 773     visitor.visit_expr_post(expression)
 774 }
 775
 776 pub fn walk_arm<V: Visitor>(visitor: &mut V, arm: &Arm) {
 777     walk_list!(visitor, visit_pat, &arm.pats);
 778     walk_list!(visitor, visit_expr, &arm.guard);
 779     visitor.visit_expr(&arm.body);
 780     walk_list!(visitor, visit_attribute, &arm.attrs);
 781 }
 782
 783 pub fn walk_vis<V: Visitor>(visitor: &mut V, vis: &Visibility) {
 784     if let Visibility::Restricted { ref path, id } = *vis {
 785         visitor.visit_path(path, id);
 786     }
 787 }