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, &'a Block),
  35
  36     /// fn foo(&self)
  37     Method(Ident, &'a MethodSig, Option<&'a Visibility>, &'a Block),
  38
  39     /// |x, y| body
  40     Closure(&'a Expr),
  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<'ast>: 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: &'ast Mod, _s: Span, _attrs: &[Attribute], _n: NodeId) {
  60         walk_mod(self, m);
  61     }
  62     fn visit_foreign_item(&mut self, i: &'ast ForeignItem) { walk_foreign_item(self, i) }
  63     fn visit_global_asm(&mut self, ga: &'ast GlobalAsm) { walk_global_asm(self, ga) }
  64     fn visit_item(&mut self, i: &'ast Item) { walk_item(self, i) }
  65     fn visit_local(&mut self, l: &'ast Local) { walk_local(self, l) }
  66     fn visit_block(&mut self, b: &'ast Block) { walk_block(self, b) }
  67     fn visit_stmt(&mut self, s: &'ast Stmt) { walk_stmt(self, s) }
  68     fn visit_arm(&mut self, a: &'ast Arm) { walk_arm(self, a) }
  69     fn visit_pat(&mut self, p: &'ast Pat) { walk_pat(self, p) }
  70     fn visit_expr(&mut self, ex: &'ast Expr) { walk_expr(self, ex) }
  71     fn visit_expr_post(&mut self, _ex: &'ast Expr) { }
  72     fn visit_ty(&mut self, t: &'ast Ty) { walk_ty(self, t) }
  73     fn visit_generics(&mut self, g: &'ast Generics) { walk_generics(self, g) }
  74     fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
  75         walk_where_predicate(self, p)
  76     }
  77     fn visit_fn(&mut self, fk: FnKind<'ast>, fd: &'ast FnDecl, s: Span, _: NodeId) {
  78         walk_fn(self, fk, fd, s)
  79     }
  80     fn visit_trait_item(&mut self, ti: &'ast TraitItem) { walk_trait_item(self, ti) }
  81     fn visit_impl_item(&mut self, ii: &'ast ImplItem) { walk_impl_item(self, ii) }
  82     fn visit_trait_ref(&mut self, t: &'ast TraitRef) { walk_trait_ref(self, t) }
  83     fn visit_ty_param_bound(&mut self, bounds: &'ast TyParamBound) {
  84         walk_ty_param_bound(self, bounds)
  85     }
  86     fn visit_poly_trait_ref(&mut self, t: &'ast PolyTraitRef, m: &'ast TraitBoundModifier) {
  87         walk_poly_trait_ref(self, t, m)
  88     }
  89     fn visit_variant_data(&mut self, s: &'ast VariantData, _: Ident,
  90                           _: &'ast Generics, _: NodeId, _: Span) {
  91         walk_struct_def(self, s)
  92     }
  93     fn visit_struct_field(&mut self, s: &'ast StructField) { walk_struct_field(self, s) }
  94     fn visit_enum_def(&mut self, enum_definition: &'ast EnumDef,
  95                       generics: &'ast Generics, item_id: NodeId, _: Span) {
  96         walk_enum_def(self, enum_definition, generics, item_id)
  97     }
  98     fn visit_variant(&mut self, v: &'ast Variant, g: &'ast Generics, item_id: NodeId) {
  99         walk_variant(self, v, g, item_id)
 100     }
 101     fn visit_lifetime(&mut self, lifetime: &'ast Lifetime) {
 102         walk_lifetime(self, lifetime)
 103     }
 104     fn visit_lifetime_def(&mut self, lifetime: &'ast LifetimeDef) {
 105         walk_lifetime_def(self, lifetime)
 106     }
 107     fn visit_mac(&mut self, _mac: &'ast Mac) {
 108         panic!("visit_mac disabled by default");
 109         // NB: see note about macros above.
 110         // if you really want a visitor that
 111         // works on macros, use this
 112         // definition in your trait impl:
 113         // visit::walk_mac(self, _mac)
 114     }
 115     fn visit_mac_def(&mut self, _mac: &'ast MacroDef, _id: NodeId) {
 116         // Nothing to do
 117     }
 118     fn visit_path(&mut self, path: &'ast Path, _id: NodeId) {
 119         walk_path(self, path)
 120     }
 121     fn visit_path_list_item(&mut self, prefix: &'ast Path, item: &'ast PathListItem) {
 122         walk_path_list_item(self, prefix, item)
 123     }
 124     fn visit_path_segment(&mut self, path_span: Span, path_segment: &'ast PathSegment) {
 125         walk_path_segment(self, path_span, path_segment)
 126     }
 127     fn visit_path_parameters(&mut self, path_span: Span, path_parameters: &'ast PathParameters) {
 128         walk_path_parameters(self, path_span, path_parameters)
 129     }
 130     fn visit_assoc_type_binding(&mut self, type_binding: &'ast TypeBinding) {
 131         walk_assoc_type_binding(self, type_binding)
 132     }
 133     fn visit_attribute(&mut self, _attr: &'ast Attribute) {}
 134     fn visit_vis(&mut self, vis: &'ast Visibility) {
 135         walk_vis(self, vis)
 136     }
 137     fn visit_fn_ret_ty(&mut self, ret_ty: &'ast FunctionRetTy) {
 138         walk_fn_ret_ty(self, ret_ty)
 139     }
 140 }
 141
 142 #[macro_export]
 143 macro_rules! walk_list {
 144     ($visitor: expr, $method: ident, $list: expr) => {
 145         for elem in $list {
 146             $visitor.$method(elem)
 147         }
 148     };
 149     ($visitor: expr, $method: ident, $list: expr, $($extra_args: expr),*) => {
 150         for elem in $list {
 151             $visitor.$method(elem, $($extra_args,)*)
 152         }
 153     }
 154 }
 155
 156 pub fn walk_opt_name<'a, V: Visitor<'a>>(visitor: &mut V, span: Span, opt_name: Option<Name>) {
 157     if let Some(name) = opt_name {
 158         visitor.visit_name(span, name);
 159     }
 160 }
 161
 162 pub fn walk_opt_ident<'a, V: Visitor<'a>>(visitor: &mut V, span: Span, opt_ident: Option<Ident>) {
 163     if let Some(ident) = opt_ident {
 164         visitor.visit_ident(span, ident);
 165     }
 166 }
 167
 168 pub fn walk_opt_sp_ident<'a, V: Visitor<'a>>(visitor: &mut V,
 169                                              opt_sp_ident: &Option<Spanned<Ident>>) {
 170     if let Some(ref sp_ident) = *opt_sp_ident {
 171         visitor.visit_ident(sp_ident.span, sp_ident.node);
 172     }
 173 }
 174
 175 pub fn walk_ident<'a, V: Visitor<'a>>(visitor: &mut V, span: Span, ident: Ident) {
 176     visitor.visit_name(span, ident.name);
 177 }
 178
 179 pub fn walk_crate<'a, V: Visitor<'a>>(visitor: &mut V, krate: &'a Crate) {
 180     visitor.visit_mod(&krate.module, krate.span, &krate.attrs, CRATE_NODE_ID);
 181     walk_list!(visitor, visit_attribute, &krate.attrs);
 182 }
 183
 184 pub fn walk_mod<'a, V: Visitor<'a>>(visitor: &mut V, module: &'a Mod) {
 185     walk_list!(visitor, visit_item, &module.items);
 186 }
 187
 188 pub fn walk_local<'a, V: Visitor<'a>>(visitor: &mut V, local: &'a 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<'a, V: Visitor<'a>>(visitor: &mut V, lifetime: &'a Lifetime) {
 198     visitor.visit_ident(lifetime.span, lifetime.ident);
 199 }
 200
 201 pub fn walk_lifetime_def<'a, V: Visitor<'a>>(visitor: &mut V, lifetime_def: &'a 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<'a, V>(visitor: &mut V,
 208                                   trait_ref: &'a PolyTraitRef,
 209                                   _: &TraitBoundModifier)
 210     where V: Visitor<'a>,
 211 {
 212     walk_list!(visitor, visit_lifetime_def, &trait_ref.bound_lifetimes);
 213     visitor.visit_trait_ref(&trait_ref.trait_ref);
 214 }
 215
 216 pub fn walk_trait_ref<'a, V: Visitor<'a>>(visitor: &mut V, trait_ref: &'a TraitRef) {
 217     visitor.visit_path(&trait_ref.path, trait_ref.ref_id)
 218 }
 219
 220 pub fn walk_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a Item) {
 221     visitor.visit_vis(&item.vis);
 222     visitor.visit_ident(item.span, item.ident);
 223     match item.node {
 224         ItemKind::ExternCrate(opt_name) => {
 225             walk_opt_name(visitor, item.span, opt_name)
 226         }
 227         ItemKind::Use(ref vp) => {
 228             match vp.node {
 229                 ViewPathSimple(ident, ref path) => {
 230                     visitor.visit_ident(vp.span, ident);
 231                     visitor.visit_path(path, item.id);
 232                 }
 233                 ViewPathGlob(ref path) => {
 234                     visitor.visit_path(path, item.id);
 235                 }
 236                 ViewPathList(ref prefix, ref list) => {
 237                     visitor.visit_path(prefix, item.id);
 238                     for item in list {
 239                         visitor.visit_path_list_item(prefix, item)
 240                     }
 241                 }
 242             }
 243         }
 244         ItemKind::Static(ref typ, _, ref expr) |
 245         ItemKind::Const(ref typ, ref expr) => {
 246             visitor.visit_ty(typ);
 247             visitor.visit_expr(expr);
 248         }
 249         ItemKind::Fn(ref declaration, unsafety, constness, abi, ref generics, ref body) => {
 250             visitor.visit_fn(FnKind::ItemFn(item.ident, generics, unsafety,
 251                                             constness, abi, &item.vis, body),
 252                              declaration,
 253                              item.span,
 254                              item.id)
 255         }
 256         ItemKind::Mod(ref module) => {
 257             visitor.visit_mod(module, item.span, &item.attrs, item.id)
 258         }
 259         ItemKind::ForeignMod(ref foreign_module) => {
 260             walk_list!(visitor, visit_foreign_item, &foreign_module.items);
 261         }
 262         ItemKind::GlobalAsm(ref ga) => visitor.visit_global_asm(ga),
 263         ItemKind::Ty(ref typ, ref type_parameters) => {
 264             visitor.visit_ty(typ);
 265             visitor.visit_generics(type_parameters)
 266         }
 267         ItemKind::Enum(ref enum_definition, ref type_parameters) => {
 268             visitor.visit_generics(type_parameters);
 269             visitor.visit_enum_def(enum_definition, type_parameters, item.id, item.span)
 270         }
 271         ItemKind::DefaultImpl(_, ref trait_ref) => {
 272             visitor.visit_trait_ref(trait_ref)
 273         }
 274         ItemKind::Impl(_, _, _,
 275                  ref type_parameters,
 276                  ref opt_trait_reference,
 277                  ref typ,
 278                  ref impl_items) => {
 279             visitor.visit_generics(type_parameters);
 280             walk_list!(visitor, visit_trait_ref, opt_trait_reference);
 281             visitor.visit_ty(typ);
 282             walk_list!(visitor, visit_impl_item, impl_items);
 283         }
 284         ItemKind::Struct(ref struct_definition, ref generics) |
 285         ItemKind::Union(ref struct_definition, ref generics) => {
 286             visitor.visit_generics(generics);
 287             visitor.visit_variant_data(struct_definition, item.ident,
 288                                      generics, item.id, item.span);
 289         }
 290         ItemKind::Trait(_, ref generics, ref bounds, ref methods) => {
 291             visitor.visit_generics(generics);
 292             walk_list!(visitor, visit_ty_param_bound, bounds);
 293             walk_list!(visitor, visit_trait_item, methods);
 294         }
 295         ItemKind::Mac(ref mac) => visitor.visit_mac(mac),
 296         ItemKind::MacroDef(ref ts) => visitor.visit_mac_def(ts, item.id),
 297     }
 298     walk_list!(visitor, visit_attribute, &item.attrs);
 299 }
 300
 301 pub fn walk_enum_def<'a, V: Visitor<'a>>(visitor: &mut V,
 302                                  enum_definition: &'a EnumDef,
 303                                  generics: &'a Generics,
 304                                  item_id: NodeId) {
 305     walk_list!(visitor, visit_variant, &enum_definition.variants, generics, item_id);
 306 }
 307
 308 pub fn walk_variant<'a, V>(visitor: &mut V,
 309                            variant: &'a Variant,
 310                            generics: &'a Generics,
 311                            item_id: NodeId)
 312     where V: Visitor<'a>,
 313 {
 314     visitor.visit_ident(variant.span, variant.node.name);
 315     visitor.visit_variant_data(&variant.node.data, variant.node.name,
 316                              generics, item_id, variant.span);
 317     walk_list!(visitor, visit_expr, &variant.node.disr_expr);
 318     walk_list!(visitor, visit_attribute, &variant.node.attrs);
 319 }
 320
 321 pub fn walk_ty<'a, V: Visitor<'a>>(visitor: &mut V, typ: &'a Ty) {
 322     match typ.node {
 323         TyKind::Slice(ref ty) | TyKind::Paren(ref ty) => {
 324             visitor.visit_ty(ty)
 325         }
 326         TyKind::Ptr(ref mutable_type) => {
 327             visitor.visit_ty(&mutable_type.ty)
 328         }
 329         TyKind::Rptr(ref opt_lifetime, ref mutable_type) => {
 330             walk_list!(visitor, visit_lifetime, opt_lifetime);
 331             visitor.visit_ty(&mutable_type.ty)
 332         }
 333         TyKind::Never => {},
 334         TyKind::Tup(ref tuple_element_types) => {
 335             walk_list!(visitor, visit_ty, tuple_element_types);
 336         }
 337         TyKind::BareFn(ref function_declaration) => {
 338             walk_fn_decl(visitor, &function_declaration.decl);
 339             walk_list!(visitor, visit_lifetime_def, &function_declaration.lifetimes);
 340         }
 341         TyKind::Path(ref maybe_qself, ref path) => {
 342             if let Some(ref qself) = *maybe_qself {
 343                 visitor.visit_ty(&qself.ty);
 344             }
 345             visitor.visit_path(path, typ.id);
 346         }
 347         TyKind::Array(ref ty, ref expression) => {
 348             visitor.visit_ty(ty);
 349             visitor.visit_expr(expression)
 350         }
 351         TyKind::TraitObject(ref bounds) |
 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 | TyKind::Err => {}
 359         TyKind::Mac(ref mac) => {
 360             visitor.visit_mac(mac)
 361         }
 362     }
 363 }
 364
 365 pub fn walk_path<'a, V: Visitor<'a>>(visitor: &mut V, path: &'a 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<'a, V: Visitor<'a>>(visitor: &mut V,
 372                                                _prefix: &Path,
 373                                                item: &'a PathListItem) {
 374     visitor.visit_ident(item.span, item.node.name);
 375     walk_opt_ident(visitor, item.span, item.node.rename);
 376 }
 377
 378 pub fn walk_path_segment<'a, V: Visitor<'a>>(visitor: &mut V,
 379                                              path_span: Span,
 380                                              segment: &'a PathSegment) {
 381     visitor.visit_ident(path_span, segment.identifier);
 382     if let Some(ref parameters) = segment.parameters {
 383         visitor.visit_path_parameters(path_span, parameters);
 384     }
 385 }
 386
 387 pub fn walk_path_parameters<'a, V>(visitor: &mut V,
 388                                    _path_span: Span,
 389                                    path_parameters: &'a PathParameters)
 390     where V: Visitor<'a>,
 391 {
 392     match *path_parameters {
 393         PathParameters::AngleBracketed(ref data) => {
 394             walk_list!(visitor, visit_ty, &data.types);
 395             walk_list!(visitor, visit_lifetime, &data.lifetimes);
 396             walk_list!(visitor, visit_assoc_type_binding, &data.bindings);
 397         }
 398         PathParameters::Parenthesized(ref data) => {
 399             walk_list!(visitor, visit_ty, &data.inputs);
 400             walk_list!(visitor, visit_ty, &data.output);
 401         }
 402     }
 403 }
 404
 405 pub fn walk_assoc_type_binding<'a, V: Visitor<'a>>(visitor: &mut V,
 406                                                    type_binding: &'a TypeBinding) {
 407     visitor.visit_ident(type_binding.span, type_binding.ident);
 408     visitor.visit_ty(&type_binding.ty);
 409 }
 410
 411 pub fn walk_pat<'a, V: Visitor<'a>>(visitor: &mut V, pattern: &'a Pat) {
 412     match pattern.node {
 413         PatKind::TupleStruct(ref path, ref children, _) => {
 414             visitor.visit_path(path, pattern.id);
 415             walk_list!(visitor, visit_pat, children);
 416         }
 417         PatKind::Path(ref opt_qself, ref path) => {
 418             if let Some(ref qself) = *opt_qself {
 419                 visitor.visit_ty(&qself.ty);
 420             }
 421             visitor.visit_path(path, pattern.id)
 422         }
 423         PatKind::Struct(ref path, ref fields, _) => {
 424             visitor.visit_path(path, pattern.id);
 425             for field in fields {
 426                 walk_list!(visitor, visit_attribute, field.node.attrs.iter());
 427                 visitor.visit_ident(field.span, field.node.ident);
 428                 visitor.visit_pat(&field.node.pat)
 429             }
 430         }
 431         PatKind::Tuple(ref tuple_elements, _) => {
 432             walk_list!(visitor, visit_pat, tuple_elements);
 433         }
 434         PatKind::Box(ref subpattern) |
 435         PatKind::Ref(ref subpattern, _) => {
 436             visitor.visit_pat(subpattern)
 437         }
 438         PatKind::Ident(_, ref pth1, ref optional_subpattern) => {
 439             visitor.visit_ident(pth1.span, pth1.node);
 440             walk_list!(visitor, visit_pat, optional_subpattern);
 441         }
 442         PatKind::Lit(ref expression) => visitor.visit_expr(expression),
 443         PatKind::Range(ref lower_bound, ref upper_bound, _) => {
 444             visitor.visit_expr(lower_bound);
 445             visitor.visit_expr(upper_bound);
 446         }
 447         PatKind::Wild => (),
 448         PatKind::Slice(ref prepatterns, ref slice_pattern, ref postpatterns) => {
 449             walk_list!(visitor, visit_pat, prepatterns);
 450             walk_list!(visitor, visit_pat, slice_pattern);
 451             walk_list!(visitor, visit_pat, postpatterns);
 452         }
 453         PatKind::Mac(ref mac) => visitor.visit_mac(mac),
 454     }
 455 }
 456
 457 pub fn walk_foreign_item<'a, V: Visitor<'a>>(visitor: &mut V, foreign_item: &'a ForeignItem) {
 458     visitor.visit_vis(&foreign_item.vis);
 459     visitor.visit_ident(foreign_item.span, foreign_item.ident);
 460
 461     match foreign_item.node {
 462         ForeignItemKind::Fn(ref function_declaration, ref generics) => {
 463             walk_fn_decl(visitor, function_declaration);
 464             visitor.visit_generics(generics)
 465         }
 466         ForeignItemKind::Static(ref typ, _) => visitor.visit_ty(typ),
 467     }
 468
 469     walk_list!(visitor, visit_attribute, &foreign_item.attrs);
 470 }
 471
 472 pub fn walk_global_asm<'a, V: Visitor<'a>>(_: &mut V, _: &'a GlobalAsm) {
 473     // Empty!
 474 }
 475
 476 pub fn walk_ty_param_bound<'a, V: Visitor<'a>>(visitor: &mut V, bound: &'a TyParamBound) {
 477     match *bound {
 478         TraitTyParamBound(ref typ, ref modifier) => {
 479             visitor.visit_poly_trait_ref(typ, modifier);
 480         }
 481         RegionTyParamBound(ref lifetime) => {
 482             visitor.visit_lifetime(lifetime);
 483         }
 484     }
 485 }
 486
 487 pub fn walk_generics<'a, V: Visitor<'a>>(visitor: &mut V, generics: &'a Generics) {
 488     for param in &generics.ty_params {
 489         visitor.visit_ident(param.span, param.ident);
 490         walk_list!(visitor, visit_ty_param_bound, &param.bounds);
 491         walk_list!(visitor, visit_ty, &param.default);
 492         walk_list!(visitor, visit_attribute, &*param.attrs);
 493     }
 494     walk_list!(visitor, visit_lifetime_def, &generics.lifetimes);
 495     walk_list!(visitor, visit_where_predicate, &generics.where_clause.predicates);
 496 }
 497
 498 pub fn walk_where_predicate<'a, V: Visitor<'a>>(visitor: &mut V, predicate: &'a WherePredicate) {
 499     match *predicate {
 500         WherePredicate::BoundPredicate(WhereBoundPredicate{ref bounded_ty,
 501                                                            ref bounds,
 502                                                            ref bound_lifetimes,
 503                                                            ..}) => {
 504             visitor.visit_ty(bounded_ty);
 505             walk_list!(visitor, visit_ty_param_bound, bounds);
 506             walk_list!(visitor, visit_lifetime_def, bound_lifetimes);
 507         }
 508         WherePredicate::RegionPredicate(WhereRegionPredicate{ref lifetime,
 509                                                              ref bounds,
 510                                                              ..}) => {
 511             visitor.visit_lifetime(lifetime);
 512             walk_list!(visitor, visit_lifetime, bounds);
 513         }
 514         WherePredicate::EqPredicate(WhereEqPredicate{ref lhs_ty,
 515                                                      ref rhs_ty,
 516                                                      ..}) => {
 517             visitor.visit_ty(lhs_ty);
 518             visitor.visit_ty(rhs_ty);
 519         }
 520     }
 521 }
 522
 523 pub fn walk_fn_ret_ty<'a, V: Visitor<'a>>(visitor: &mut V, ret_ty: &'a FunctionRetTy) {
 524     if let FunctionRetTy::Ty(ref output_ty) = *ret_ty {
 525         visitor.visit_ty(output_ty)
 526     }
 527 }
 528
 529 pub fn walk_fn_decl<'a, V: Visitor<'a>>(visitor: &mut V, function_declaration: &'a FnDecl) {
 530     for argument in &function_declaration.inputs {
 531         visitor.visit_pat(&argument.pat);
 532         visitor.visit_ty(&argument.ty)
 533     }
 534     visitor.visit_fn_ret_ty(&function_declaration.output)
 535 }
 536
 537 pub fn walk_fn<'a, V>(visitor: &mut V, kind: FnKind<'a>, declaration: &'a FnDecl, _span: Span)
 538     where V: Visitor<'a>,
 539 {
 540     match kind {
 541         FnKind::ItemFn(_, generics, _, _, _, _, body) => {
 542             visitor.visit_generics(generics);
 543             walk_fn_decl(visitor, declaration);
 544             visitor.visit_block(body);
 545         }
 546         FnKind::Method(_, sig, _, body) => {
 547             visitor.visit_generics(&sig.generics);
 548             walk_fn_decl(visitor, declaration);
 549             visitor.visit_block(body);
 550         }
 551         FnKind::Closure(body) => {
 552             walk_fn_decl(visitor, declaration);
 553             visitor.visit_expr(body);
 554         }
 555     }
 556 }
 557
 558 pub fn walk_trait_item<'a, V: Visitor<'a>>(visitor: &mut V, trait_item: &'a TraitItem) {
 559     visitor.visit_ident(trait_item.span, trait_item.ident);
 560     walk_list!(visitor, visit_attribute, &trait_item.attrs);
 561     match trait_item.node {
 562         TraitItemKind::Const(ref ty, ref default) => {
 563             visitor.visit_ty(ty);
 564             walk_list!(visitor, visit_expr, default);
 565         }
 566         TraitItemKind::Method(ref sig, None) => {
 567             visitor.visit_generics(&sig.generics);
 568             walk_fn_decl(visitor, &sig.decl);
 569         }
 570         TraitItemKind::Method(ref sig, Some(ref body)) => {
 571             visitor.visit_fn(FnKind::Method(trait_item.ident, sig, None, body),
 572                              &sig.decl, trait_item.span, trait_item.id);
 573         }
 574         TraitItemKind::Type(ref bounds, ref default) => {
 575             walk_list!(visitor, visit_ty_param_bound, bounds);
 576             walk_list!(visitor, visit_ty, default);
 577         }
 578         TraitItemKind::Macro(ref mac) => {
 579             visitor.visit_mac(mac);
 580         }
 581     }
 582 }
 583
 584 pub fn walk_impl_item<'a, V: Visitor<'a>>(visitor: &mut V, impl_item: &'a ImplItem) {
 585     visitor.visit_vis(&impl_item.vis);
 586     visitor.visit_ident(impl_item.span, impl_item.ident);
 587     walk_list!(visitor, visit_attribute, &impl_item.attrs);
 588     match impl_item.node {
 589         ImplItemKind::Const(ref ty, ref expr) => {
 590             visitor.visit_ty(ty);
 591             visitor.visit_expr(expr);
 592         }
 593         ImplItemKind::Method(ref sig, ref body) => {
 594             visitor.visit_fn(FnKind::Method(impl_item.ident, sig, Some(&impl_item.vis), body),
 595                              &sig.decl, impl_item.span, impl_item.id);
 596         }
 597         ImplItemKind::Type(ref ty) => {
 598             visitor.visit_ty(ty);
 599         }
 600         ImplItemKind::Macro(ref mac) => {
 601             visitor.visit_mac(mac);
 602         }
 603     }
 604 }
 605
 606 pub fn walk_struct_def<'a, V: Visitor<'a>>(visitor: &mut V, struct_definition: &'a VariantData) {
 607     walk_list!(visitor, visit_struct_field, struct_definition.fields());
 608 }
 609
 610 pub fn walk_struct_field<'a, V: Visitor<'a>>(visitor: &mut V, struct_field: &'a StructField) {
 611     visitor.visit_vis(&struct_field.vis);
 612     walk_opt_ident(visitor, struct_field.span, struct_field.ident);
 613     visitor.visit_ty(&struct_field.ty);
 614     walk_list!(visitor, visit_attribute, &struct_field.attrs);
 615 }
 616
 617 pub fn walk_block<'a, V: Visitor<'a>>(visitor: &mut V, block: &'a Block) {
 618     walk_list!(visitor, visit_stmt, &block.stmts);
 619 }
 620
 621 pub fn walk_stmt<'a, V: Visitor<'a>>(visitor: &mut V, statement: &'a Stmt) {
 622     match statement.node {
 623         StmtKind::Local(ref local) => visitor.visit_local(local),
 624         StmtKind::Item(ref item) => visitor.visit_item(item),
 625         StmtKind::Expr(ref expression) | StmtKind::Semi(ref expression) => {
 626             visitor.visit_expr(expression)
 627         }
 628         StmtKind::Mac(ref mac) => {
 629             let (ref mac, _, ref attrs) = **mac;
 630             visitor.visit_mac(mac);
 631             for attr in attrs.iter() {
 632                 visitor.visit_attribute(attr);
 633             }
 634         }
 635     }
 636 }
 637
 638 pub fn walk_mac<'a, V: Visitor<'a>>(_: &mut V, _: &Mac) {
 639     // Empty!
 640 }
 641
 642 pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
 643     for attr in expression.attrs.iter() {
 644         visitor.visit_attribute(attr);
 645     }
 646     match expression.node {
 647         ExprKind::Box(ref subexpression) => {
 648             visitor.visit_expr(subexpression)
 649         }
 650         ExprKind::InPlace(ref place, ref subexpression) => {
 651             visitor.visit_expr(place);
 652             visitor.visit_expr(subexpression)
 653         }
 654         ExprKind::Array(ref subexpressions) => {
 655             walk_list!(visitor, visit_expr, subexpressions);
 656         }
 657         ExprKind::Repeat(ref element, ref count) => {
 658             visitor.visit_expr(element);
 659             visitor.visit_expr(count)
 660         }
 661         ExprKind::Struct(ref path, ref fields, ref optional_base) => {
 662             visitor.visit_path(path, expression.id);
 663             for field in fields {
 664                 walk_list!(visitor, visit_attribute, field.attrs.iter());
 665                 visitor.visit_ident(field.ident.span, field.ident.node);
 666                 visitor.visit_expr(&field.expr)
 667             }
 668             walk_list!(visitor, visit_expr, optional_base);
 669         }
 670         ExprKind::Tup(ref subexpressions) => {
 671             walk_list!(visitor, visit_expr, subexpressions);
 672         }
 673         ExprKind::Call(ref callee_expression, ref arguments) => {
 674             visitor.visit_expr(callee_expression);
 675             walk_list!(visitor, visit_expr, arguments);
 676         }
 677         ExprKind::MethodCall(ref segment, ref arguments) => {
 678             visitor.visit_path_segment(expression.span, segment);
 679             walk_list!(visitor, visit_expr, arguments);
 680         }
 681         ExprKind::Binary(_, ref left_expression, ref right_expression) => {
 682             visitor.visit_expr(left_expression);
 683             visitor.visit_expr(right_expression)
 684         }
 685         ExprKind::AddrOf(_, ref subexpression) | ExprKind::Unary(_, ref subexpression) => {
 686             visitor.visit_expr(subexpression)
 687         }
 688         ExprKind::Lit(_) => {}
 689         ExprKind::Cast(ref subexpression, ref typ) | ExprKind::Type(ref subexpression, ref typ) => {
 690             visitor.visit_expr(subexpression);
 691             visitor.visit_ty(typ)
 692         }
 693         ExprKind::If(ref head_expression, ref if_block, ref optional_else) => {
 694             visitor.visit_expr(head_expression);
 695             visitor.visit_block(if_block);
 696             walk_list!(visitor, visit_expr, optional_else);
 697         }
 698         ExprKind::While(ref subexpression, ref block, ref opt_sp_ident) => {
 699             visitor.visit_expr(subexpression);
 700             visitor.visit_block(block);
 701             walk_opt_sp_ident(visitor, opt_sp_ident);
 702         }
 703         ExprKind::IfLet(ref pattern, ref subexpression, ref if_block, ref optional_else) => {
 704             visitor.visit_pat(pattern);
 705             visitor.visit_expr(subexpression);
 706             visitor.visit_block(if_block);
 707             walk_list!(visitor, visit_expr, optional_else);
 708         }
 709         ExprKind::WhileLet(ref pattern, ref subexpression, ref block, ref opt_sp_ident) => {
 710             visitor.visit_pat(pattern);
 711             visitor.visit_expr(subexpression);
 712             visitor.visit_block(block);
 713             walk_opt_sp_ident(visitor, opt_sp_ident);
 714         }
 715         ExprKind::ForLoop(ref pattern, ref subexpression, ref block, ref opt_sp_ident) => {
 716             visitor.visit_pat(pattern);
 717             visitor.visit_expr(subexpression);
 718             visitor.visit_block(block);
 719             walk_opt_sp_ident(visitor, opt_sp_ident);
 720         }
 721         ExprKind::Loop(ref block, ref opt_sp_ident) => {
 722             visitor.visit_block(block);
 723             walk_opt_sp_ident(visitor, opt_sp_ident);
 724         }
 725         ExprKind::Match(ref subexpression, ref arms) => {
 726             visitor.visit_expr(subexpression);
 727             walk_list!(visitor, visit_arm, arms);
 728         }
 729         ExprKind::Closure(_, ref function_declaration, ref body, _decl_span) => {
 730             visitor.visit_fn(FnKind::Closure(body),
 731                              function_declaration,
 732                              expression.span,
 733                              expression.id)
 734         }
 735         ExprKind::Block(ref block) => visitor.visit_block(block),
 736         ExprKind::Assign(ref left_hand_expression, ref right_hand_expression) => {
 737             visitor.visit_expr(left_hand_expression);
 738             visitor.visit_expr(right_hand_expression);
 739         }
 740         ExprKind::AssignOp(_, ref left_expression, ref right_expression) => {
 741             visitor.visit_expr(left_expression);
 742             visitor.visit_expr(right_expression);
 743         }
 744         ExprKind::Field(ref subexpression, ref ident) => {
 745             visitor.visit_expr(subexpression);
 746             visitor.visit_ident(ident.span, ident.node);
 747         }
 748         ExprKind::TupField(ref subexpression, _) => {
 749             visitor.visit_expr(subexpression);
 750         }
 751         ExprKind::Index(ref main_expression, ref index_expression) => {
 752             visitor.visit_expr(main_expression);
 753             visitor.visit_expr(index_expression)
 754         }
 755         ExprKind::Range(ref start, ref end, _) => {
 756             walk_list!(visitor, visit_expr, start);
 757             walk_list!(visitor, visit_expr, end);
 758         }
 759         ExprKind::Path(ref maybe_qself, ref path) => {
 760             if let Some(ref qself) = *maybe_qself {
 761                 visitor.visit_ty(&qself.ty);
 762             }
 763             visitor.visit_path(path, expression.id)
 764         }
 765         ExprKind::Break(ref opt_sp_ident, ref opt_expr) => {
 766             walk_opt_sp_ident(visitor, opt_sp_ident);
 767             walk_list!(visitor, visit_expr, opt_expr);
 768         }
 769         ExprKind::Continue(ref opt_sp_ident) => {
 770             walk_opt_sp_ident(visitor, opt_sp_ident);
 771         }
 772         ExprKind::Ret(ref optional_expression) => {
 773             walk_list!(visitor, visit_expr, optional_expression);
 774         }
 775         ExprKind::Mac(ref mac) => visitor.visit_mac(mac),
 776         ExprKind::Paren(ref subexpression) => {
 777             visitor.visit_expr(subexpression)
 778         }
 779         ExprKind::InlineAsm(ref ia) => {
 780             for &(_, ref input) in &ia.inputs {
 781                 visitor.visit_expr(input)
 782             }
 783             for output in &ia.outputs {
 784                 visitor.visit_expr(&output.expr)
 785             }
 786         }
 787         ExprKind::Try(ref subexpression) => {
 788             visitor.visit_expr(subexpression)
 789         }
 790         ExprKind::Catch(ref body) => {
 791             visitor.visit_block(body)
 792         }
 793     }
 794
 795     visitor.visit_expr_post(expression)
 796 }
 797
 798 pub fn walk_arm<'a, V: Visitor<'a>>(visitor: &mut V, arm: &'a 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 }
 804
 805 pub fn walk_vis<'a, V: Visitor<'a>>(visitor: &mut V, vis: &'a Visibility) {
 806     if let Visibility::Restricted { ref path, id } = *vis {
 807         visitor.visit_path(path, id);
 808     }
 809 }