src/librustc_front/fold.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 //! A Folder represents an HIR->HIR fold; it accepts a HIR piece,
  12 //! and returns a piece of the same type.
  13
  14 use hir::*;
  15 use syntax::ast::{Name, NodeId, DUMMY_NODE_ID, Attribute, Attribute_, MetaItem};
  16 use syntax::ast::MetaItemKind;
  17 use syntax::attr::ThinAttributesExt;
  18 use hir;
  19 use syntax::codemap::{respan, Span, Spanned};
  20 use syntax::ptr::P;
  21 use syntax::parse::token;
  22 use syntax::util::move_map::MoveMap;
  23
  24 pub trait Folder : Sized {
  25     // Any additions to this trait should happen in form
  26     // of a call to a public `noop_*` function that only calls
  27     // out to the folder again, not other `noop_*` functions.
  28     //
  29     // This is a necessary API workaround to the problem of not
  30     // being able to call out to the super default method
  31     // in an overridden default method.
  32
  33     fn fold_crate(&mut self, c: Crate) -> Crate {
  34         noop_fold_crate(c, self)
  35     }
  36
  37     fn fold_meta_items(&mut self, meta_items: HirVec<P<MetaItem>>) -> HirVec<P<MetaItem>> {
  38         noop_fold_meta_items(meta_items, self)
  39     }
  40
  41     fn fold_meta_item(&mut self, meta_item: P<MetaItem>) -> P<MetaItem> {
  42         noop_fold_meta_item(meta_item, self)
  43     }
  44
  45     fn fold_view_path(&mut self, view_path: P<ViewPath>) -> P<ViewPath> {
  46         noop_fold_view_path(view_path, self)
  47     }
  48
  49     fn fold_foreign_item(&mut self, ni: ForeignItem) -> ForeignItem {
  50         noop_fold_foreign_item(ni, self)
  51     }
  52
  53     fn fold_item(&mut self, i: Item) -> Item {
  54         noop_fold_item(i, self)
  55     }
  56
  57     fn fold_item_id(&mut self, i: ItemId) -> ItemId {
  58         noop_fold_item_id(i, self)
  59     }
  60
  61     fn fold_struct_field(&mut self, sf: StructField) -> StructField {
  62         noop_fold_struct_field(sf, self)
  63     }
  64
  65     fn fold_item_underscore(&mut self, i: Item_) -> Item_ {
  66         noop_fold_item_underscore(i, self)
  67     }
  68
  69     fn fold_trait_item(&mut self, i: TraitItem) -> TraitItem {
  70         noop_fold_trait_item(i, self)
  71     }
  72
  73     fn fold_impl_item(&mut self, i: ImplItem) -> ImplItem {
  74         noop_fold_impl_item(i, self)
  75     }
  76
  77     fn fold_fn_decl(&mut self, d: P<FnDecl>) -> P<FnDecl> {
  78         noop_fold_fn_decl(d, self)
  79     }
  80
  81     fn fold_block(&mut self, b: P<Block>) -> P<Block> {
  82         noop_fold_block(b, self)
  83     }
  84
  85     fn fold_stmt(&mut self, s: Stmt) -> Stmt {
  86         noop_fold_stmt(s, self)
  87     }
  88
  89     fn fold_arm(&mut self, a: Arm) -> Arm {
  90         noop_fold_arm(a, self)
  91     }
  92
  93     fn fold_pat(&mut self, p: P<Pat>) -> P<Pat> {
  94         noop_fold_pat(p, self)
  95     }
  96
  97     fn fold_decl(&mut self, d: P<Decl>) -> P<Decl> {
  98         noop_fold_decl(d, self)
  99     }
 100
 101     fn fold_expr(&mut self, e: P<Expr>) -> P<Expr> {
 102         e.map(|e| noop_fold_expr(e, self))
 103     }
 104
 105     fn fold_ty(&mut self, t: P<Ty>) -> P<Ty> {
 106         noop_fold_ty(t, self)
 107     }
 108
 109     fn fold_ty_binding(&mut self, t: TypeBinding) -> TypeBinding {
 110         noop_fold_ty_binding(t, self)
 111     }
 112
 113     fn fold_mod(&mut self, m: Mod) -> Mod {
 114         noop_fold_mod(m, self)
 115     }
 116
 117     fn fold_foreign_mod(&mut self, nm: ForeignMod) -> ForeignMod {
 118         noop_fold_foreign_mod(nm, self)
 119     }
 120
 121     fn fold_variant(&mut self, v: Variant) -> Variant {
 122         noop_fold_variant(v, self)
 123     }
 124
 125     fn fold_name(&mut self, n: Name) -> Name {
 126         noop_fold_name(n, self)
 127     }
 128
 129     fn fold_ident(&mut self, i: Ident) -> Ident {
 130         noop_fold_ident(i, self)
 131     }
 132
 133     fn fold_usize(&mut self, i: usize) -> usize {
 134         noop_fold_usize(i, self)
 135     }
 136
 137     fn fold_path(&mut self, p: Path) -> Path {
 138         noop_fold_path(p, self)
 139     }
 140
 141     fn fold_path_parameters(&mut self, p: PathParameters) -> PathParameters {
 142         noop_fold_path_parameters(p, self)
 143     }
 144
 145     fn fold_angle_bracketed_parameter_data(&mut self,
 146                                            p: AngleBracketedParameterData)
 147                                            -> AngleBracketedParameterData {
 148         noop_fold_angle_bracketed_parameter_data(p, self)
 149     }
 150
 151     fn fold_parenthesized_parameter_data(&mut self,
 152                                          p: ParenthesizedParameterData)
 153                                          -> ParenthesizedParameterData {
 154         noop_fold_parenthesized_parameter_data(p, self)
 155     }
 156
 157     fn fold_local(&mut self, l: P<Local>) -> P<Local> {
 158         noop_fold_local(l, self)
 159     }
 160
 161     fn fold_explicit_self(&mut self, es: ExplicitSelf) -> ExplicitSelf {
 162         noop_fold_explicit_self(es, self)
 163     }
 164
 165     fn fold_explicit_self_underscore(&mut self, es: ExplicitSelf_) -> ExplicitSelf_ {
 166         noop_fold_explicit_self_underscore(es, self)
 167     }
 168
 169     fn fold_lifetime(&mut self, l: Lifetime) -> Lifetime {
 170         noop_fold_lifetime(l, self)
 171     }
 172
 173     fn fold_lifetime_def(&mut self, l: LifetimeDef) -> LifetimeDef {
 174         noop_fold_lifetime_def(l, self)
 175     }
 176
 177     fn fold_attribute(&mut self, at: Attribute) -> Option<Attribute> {
 178         noop_fold_attribute(at, self)
 179     }
 180
 181     fn fold_arg(&mut self, a: Arg) -> Arg {
 182         noop_fold_arg(a, self)
 183     }
 184
 185     fn fold_generics(&mut self, generics: Generics) -> Generics {
 186         noop_fold_generics(generics, self)
 187     }
 188
 189     fn fold_trait_ref(&mut self, p: TraitRef) -> TraitRef {
 190         noop_fold_trait_ref(p, self)
 191     }
 192
 193     fn fold_poly_trait_ref(&mut self, p: PolyTraitRef) -> PolyTraitRef {
 194         noop_fold_poly_trait_ref(p, self)
 195     }
 196
 197     fn fold_variant_data(&mut self, vdata: VariantData) -> VariantData {
 198         noop_fold_variant_data(vdata, self)
 199     }
 200
 201     fn fold_lifetimes(&mut self, lts: HirVec<Lifetime>) -> HirVec<Lifetime> {
 202         noop_fold_lifetimes(lts, self)
 203     }
 204
 205     fn fold_lifetime_defs(&mut self, lts: HirVec<LifetimeDef>) -> HirVec<LifetimeDef> {
 206         noop_fold_lifetime_defs(lts, self)
 207     }
 208
 209     fn fold_ty_param(&mut self, tp: TyParam) -> TyParam {
 210         noop_fold_ty_param(tp, self)
 211     }
 212
 213     fn fold_ty_params(&mut self, tps: HirVec<TyParam>) -> HirVec<TyParam> {
 214         noop_fold_ty_params(tps, self)
 215     }
 216
 217     fn fold_opt_lifetime(&mut self, o_lt: Option<Lifetime>) -> Option<Lifetime> {
 218         noop_fold_opt_lifetime(o_lt, self)
 219     }
 220
 221     fn fold_opt_bounds(&mut self,
 222                        b: Option<TyParamBounds>)
 223                        -> Option<TyParamBounds> {
 224         noop_fold_opt_bounds(b, self)
 225     }
 226
 227     fn fold_bounds(&mut self, b: TyParamBounds) -> TyParamBounds {
 228         noop_fold_bounds(b, self)
 229     }
 230
 231     fn fold_ty_param_bound(&mut self, tpb: TyParamBound) -> TyParamBound {
 232         noop_fold_ty_param_bound(tpb, self)
 233     }
 234
 235     fn fold_mt(&mut self, mt: MutTy) -> MutTy {
 236         noop_fold_mt(mt, self)
 237     }
 238
 239     fn fold_field(&mut self, field: Field) -> Field {
 240         noop_fold_field(field, self)
 241     }
 242
 243     fn fold_where_clause(&mut self, where_clause: WhereClause) -> WhereClause {
 244         noop_fold_where_clause(where_clause, self)
 245     }
 246
 247     fn fold_where_predicate(&mut self, where_predicate: WherePredicate) -> WherePredicate {
 248         noop_fold_where_predicate(where_predicate, self)
 249     }
 250
 251     /// called for the `id` on each declaration
 252     fn new_id(&mut self, i: NodeId) -> NodeId {
 253         i
 254     }
 255
 256     /// called for ids that are references (e.g., ItemDef)
 257     fn map_id(&mut self, i: NodeId) -> NodeId {
 258         i
 259     }
 260
 261     fn new_span(&mut self, sp: Span) -> Span {
 262         sp
 263     }
 264 }
 265
 266 pub fn noop_fold_meta_items<T: Folder>(meta_items: HirVec<P<MetaItem>>,
 267                                        fld: &mut T)
 268                                        -> HirVec<P<MetaItem>> {
 269     meta_items.move_map(|x| fld.fold_meta_item(x))
 270 }
 271
 272 pub fn noop_fold_view_path<T: Folder>(view_path: P<ViewPath>, fld: &mut T) -> P<ViewPath> {
 273     view_path.map(|Spanned { node, span }| {
 274         Spanned {
 275             node: match node {
 276                 ViewPathSimple(name, path) => {
 277                     ViewPathSimple(name, fld.fold_path(path))
 278                 }
 279                 ViewPathGlob(path) => {
 280                     ViewPathGlob(fld.fold_path(path))
 281                 }
 282                 ViewPathList(path, path_list_idents) => {
 283                     ViewPathList(fld.fold_path(path),
 284                                  path_list_idents.move_map(|path_list_ident| {
 285                                      Spanned {
 286                                          node: match path_list_ident.node {
 287                                              PathListIdent { id, name, rename } => PathListIdent {
 288                                                  id: fld.new_id(id),
 289                                                  name: name,
 290                                                  rename: rename,
 291                                              },
 292                                              PathListMod { id, rename } => PathListMod {
 293                                                  id: fld.new_id(id),
 294                                                  rename: rename,
 295                                              },
 296                                          },
 297                                          span: fld.new_span(path_list_ident.span),
 298                                      }
 299                                  }))
 300                 }
 301             },
 302             span: fld.new_span(span),
 303         }
 304     })
 305 }
 306
 307 pub fn fold_attrs<T: Folder>(attrs: HirVec<Attribute>, fld: &mut T) -> HirVec<Attribute> {
 308     attrs.move_flat_map(|x| fld.fold_attribute(x))
 309 }
 310
 311 pub fn noop_fold_arm<T: Folder>(Arm { attrs, pats, guard, body }: Arm, fld: &mut T) -> Arm {
 312     Arm {
 313         attrs: fold_attrs(attrs, fld),
 314         pats: pats.move_map(|x| fld.fold_pat(x)),
 315         guard: guard.map(|x| fld.fold_expr(x)),
 316         body: fld.fold_expr(body),
 317     }
 318 }
 319
 320 pub fn noop_fold_decl<T: Folder>(d: P<Decl>, fld: &mut T) -> P<Decl> {
 321     d.map(|Spanned { node, span }| {
 322         match node {
 323             DeclLocal(l) => Spanned {
 324                 node: DeclLocal(fld.fold_local(l)),
 325                 span: fld.new_span(span),
 326             },
 327             DeclItem(it) => Spanned {
 328                 node: DeclItem(fld.fold_item_id(it)),
 329                 span: fld.new_span(span),
 330             },
 331         }
 332     })
 333 }
 334
 335 pub fn noop_fold_ty_binding<T: Folder>(b: TypeBinding, fld: &mut T) -> TypeBinding {
 336     TypeBinding {
 337         id: fld.new_id(b.id),
 338         name: b.name,
 339         ty: fld.fold_ty(b.ty),
 340         span: fld.new_span(b.span),
 341     }
 342 }
 343
 344 pub fn noop_fold_ty<T: Folder>(t: P<Ty>, fld: &mut T) -> P<Ty> {
 345     t.map(|Ty { id, node, span }| {
 346         Ty {
 347             id: fld.new_id(id),
 348             node: match node {
 349                 TyInfer => node,
 350                 TyVec(ty) => TyVec(fld.fold_ty(ty)),
 351                 TyPtr(mt) => TyPtr(fld.fold_mt(mt)),
 352                 TyRptr(region, mt) => {
 353                     TyRptr(fld.fold_opt_lifetime(region), fld.fold_mt(mt))
 354                 }
 355                 TyBareFn(f) => {
 356                     TyBareFn(f.map(|BareFnTy { lifetimes, unsafety, abi, decl }| {
 357                         BareFnTy {
 358                             lifetimes: fld.fold_lifetime_defs(lifetimes),
 359                             unsafety: unsafety,
 360                             abi: abi,
 361                             decl: fld.fold_fn_decl(decl),
 362                         }
 363                     }))
 364                 }
 365                 TyTup(tys) => TyTup(tys.move_map(|ty| fld.fold_ty(ty))),
 366                 TyPath(qself, path) => {
 367                     let qself = qself.map(|QSelf { ty, position }| {
 368                         QSelf {
 369                             ty: fld.fold_ty(ty),
 370                             position: position,
 371                         }
 372                     });
 373                     TyPath(qself, fld.fold_path(path))
 374                 }
 375                 TyObjectSum(ty, bounds) => {
 376                     TyObjectSum(fld.fold_ty(ty), fld.fold_bounds(bounds))
 377                 }
 378                 TyFixedLengthVec(ty, e) => {
 379                     TyFixedLengthVec(fld.fold_ty(ty), fld.fold_expr(e))
 380                 }
 381                 TyTypeof(expr) => {
 382                     TyTypeof(fld.fold_expr(expr))
 383                 }
 384                 TyPolyTraitRef(bounds) => {
 385                     TyPolyTraitRef(bounds.move_map(|b| fld.fold_ty_param_bound(b)))
 386                 }
 387             },
 388             span: fld.new_span(span),
 389         }
 390     })
 391 }
 392
 393 pub fn noop_fold_foreign_mod<T: Folder>(ForeignMod { abi, items }: ForeignMod,
 394                                         fld: &mut T)
 395                                         -> ForeignMod {
 396     ForeignMod {
 397         abi: abi,
 398         items: items.move_map(|x| fld.fold_foreign_item(x)),
 399     }
 400 }
 401
 402 pub fn noop_fold_variant<T: Folder>(v: Variant, fld: &mut T) -> Variant {
 403     Spanned {
 404         node: Variant_ {
 405             name: v.node.name,
 406             attrs: fold_attrs(v.node.attrs, fld),
 407             data: fld.fold_variant_data(v.node.data),
 408             disr_expr: v.node.disr_expr.map(|e| fld.fold_expr(e)),
 409         },
 410         span: fld.new_span(v.span),
 411     }
 412 }
 413
 414 pub fn noop_fold_name<T: Folder>(n: Name, _: &mut T) -> Name {
 415     n
 416 }
 417
 418 pub fn noop_fold_ident<T: Folder>(i: Ident, _: &mut T) -> Ident {
 419     i
 420 }
 421
 422 pub fn noop_fold_usize<T: Folder>(i: usize, _: &mut T) -> usize {
 423     i
 424 }
 425
 426 pub fn noop_fold_path<T: Folder>(Path { global, segments, span }: Path, fld: &mut T) -> Path {
 427     Path {
 428         global: global,
 429         segments: segments.move_map(|PathSegment { identifier, parameters }| {
 430             PathSegment {
 431                 identifier: fld.fold_ident(identifier),
 432                 parameters: fld.fold_path_parameters(parameters),
 433             }
 434         }),
 435         span: fld.new_span(span),
 436     }
 437 }
 438
 439 pub fn noop_fold_path_parameters<T: Folder>(path_parameters: PathParameters,
 440                                             fld: &mut T)
 441                                             -> PathParameters {
 442     match path_parameters {
 443         AngleBracketedParameters(data) =>
 444             AngleBracketedParameters(fld.fold_angle_bracketed_parameter_data(data)),
 445         ParenthesizedParameters(data) =>
 446             ParenthesizedParameters(fld.fold_parenthesized_parameter_data(data)),
 447     }
 448 }
 449
 450 pub fn noop_fold_angle_bracketed_parameter_data<T: Folder>(data: AngleBracketedParameterData,
 451                                                            fld: &mut T)
 452                                                            -> AngleBracketedParameterData {
 453     let AngleBracketedParameterData { lifetimes, types, bindings } = data;
 454     AngleBracketedParameterData {
 455         lifetimes: fld.fold_lifetimes(lifetimes),
 456         types: types.move_map(|ty| fld.fold_ty(ty)),
 457         bindings: bindings.move_map(|b| fld.fold_ty_binding(b)),
 458     }
 459 }
 460
 461 pub fn noop_fold_parenthesized_parameter_data<T: Folder>(data: ParenthesizedParameterData,
 462                                                          fld: &mut T)
 463                                                          -> ParenthesizedParameterData {
 464     let ParenthesizedParameterData { inputs, output, span } = data;
 465     ParenthesizedParameterData {
 466         inputs: inputs.move_map(|ty| fld.fold_ty(ty)),
 467         output: output.map(|ty| fld.fold_ty(ty)),
 468         span: fld.new_span(span),
 469     }
 470 }
 471
 472 pub fn noop_fold_local<T: Folder>(l: P<Local>, fld: &mut T) -> P<Local> {
 473     l.map(|Local { id, pat, ty, init, span, attrs }| {
 474         Local {
 475             id: fld.new_id(id),
 476             ty: ty.map(|t| fld.fold_ty(t)),
 477             pat: fld.fold_pat(pat),
 478             init: init.map(|e| fld.fold_expr(e)),
 479             span: fld.new_span(span),
 480             attrs: attrs.map_thin_attrs(|attrs| fold_attrs(attrs.into(), fld).into()),
 481         }
 482     })
 483 }
 484
 485 pub fn noop_fold_attribute<T: Folder>(at: Attribute, fld: &mut T) -> Option<Attribute> {
 486     let Spanned {node: Attribute_ {id, style, value, is_sugared_doc}, span} = at;
 487     Some(Spanned {
 488         node: Attribute_ {
 489             id: id,
 490             style: style,
 491             value: fld.fold_meta_item(value),
 492             is_sugared_doc: is_sugared_doc,
 493         },
 494         span: fld.new_span(span),
 495     })
 496 }
 497
 498 pub fn noop_fold_explicit_self_underscore<T: Folder>(es: ExplicitSelf_,
 499                                                      fld: &mut T)
 500                                                      -> ExplicitSelf_ {
 501     match es {
 502         SelfStatic | SelfValue(_) => es,
 503         SelfRegion(lifetime, m, name) => {
 504             SelfRegion(fld.fold_opt_lifetime(lifetime), m, name)
 505         }
 506         SelfExplicit(typ, name) => {
 507             SelfExplicit(fld.fold_ty(typ), name)
 508         }
 509     }
 510 }
 511
 512 pub fn noop_fold_explicit_self<T: Folder>(Spanned { span, node }: ExplicitSelf,
 513                                           fld: &mut T)
 514                                           -> ExplicitSelf {
 515     Spanned {
 516         node: fld.fold_explicit_self_underscore(node),
 517         span: fld.new_span(span),
 518     }
 519 }
 520
 521 pub fn noop_fold_meta_item<T: Folder>(mi: P<MetaItem>, fld: &mut T) -> P<MetaItem> {
 522     mi.map(|Spanned { node, span }| {
 523         Spanned {
 524             node: match node {
 525                 MetaItemKind::Word(id) => MetaItemKind::Word(id),
 526                 MetaItemKind::List(id, mis) => {
 527                     MetaItemKind::List(id, mis.move_map(|e| fld.fold_meta_item(e)))
 528                 }
 529                 MetaItemKind::NameValue(id, s) => MetaItemKind::NameValue(id, s),
 530             },
 531             span: fld.new_span(span),
 532         }
 533     })
 534 }
 535
 536 pub fn noop_fold_arg<T: Folder>(Arg { id, pat, ty }: Arg, fld: &mut T) -> Arg {
 537     Arg {
 538         id: fld.new_id(id),
 539         pat: fld.fold_pat(pat),
 540         ty: fld.fold_ty(ty),
 541     }
 542 }
 543
 544 pub fn noop_fold_fn_decl<T: Folder>(decl: P<FnDecl>, fld: &mut T) -> P<FnDecl> {
 545     decl.map(|FnDecl { inputs, output, variadic }| {
 546         FnDecl {
 547             inputs: inputs.move_map(|x| fld.fold_arg(x)),
 548             output: match output {
 549                 Return(ty) => Return(fld.fold_ty(ty)),
 550                 DefaultReturn(span) => DefaultReturn(span),
 551                 NoReturn(span) => NoReturn(span),
 552             },
 553             variadic: variadic,
 554         }
 555     })
 556 }
 557
 558 pub fn noop_fold_ty_param_bound<T>(tpb: TyParamBound, fld: &mut T) -> TyParamBound
 559     where T: Folder
 560 {
 561     match tpb {
 562         TraitTyParamBound(ty, modifier) => TraitTyParamBound(fld.fold_poly_trait_ref(ty), modifier),
 563         RegionTyParamBound(lifetime) => RegionTyParamBound(fld.fold_lifetime(lifetime)),
 564     }
 565 }
 566
 567 pub fn noop_fold_ty_param<T: Folder>(tp: TyParam, fld: &mut T) -> TyParam {
 568     let TyParam {id, name, bounds, default, span} = tp;
 569     TyParam {
 570         id: fld.new_id(id),
 571         name: name,
 572         bounds: fld.fold_bounds(bounds),
 573         default: default.map(|x| fld.fold_ty(x)),
 574         span: span,
 575     }
 576 }
 577
 578 pub fn noop_fold_ty_params<T: Folder>(tps: HirVec<TyParam>,
 579                                       fld: &mut T)
 580                                       -> HirVec<TyParam> {
 581     tps.move_map(|tp| fld.fold_ty_param(tp))
 582 }
 583
 584 pub fn noop_fold_lifetime<T: Folder>(l: Lifetime, fld: &mut T) -> Lifetime {
 585     Lifetime {
 586         id: fld.new_id(l.id),
 587         name: l.name,
 588         span: fld.new_span(l.span),
 589     }
 590 }
 591
 592 pub fn noop_fold_lifetime_def<T: Folder>(l: LifetimeDef, fld: &mut T) -> LifetimeDef {
 593     LifetimeDef {
 594         lifetime: fld.fold_lifetime(l.lifetime),
 595         bounds: fld.fold_lifetimes(l.bounds),
 596     }
 597 }
 598
 599 pub fn noop_fold_lifetimes<T: Folder>(lts: HirVec<Lifetime>, fld: &mut T) -> HirVec<Lifetime> {
 600     lts.move_map(|l| fld.fold_lifetime(l))
 601 }
 602
 603 pub fn noop_fold_lifetime_defs<T: Folder>(lts: HirVec<LifetimeDef>,
 604                                           fld: &mut T)
 605                                           -> HirVec<LifetimeDef> {
 606     lts.move_map(|l| fld.fold_lifetime_def(l))
 607 }
 608
 609 pub fn noop_fold_opt_lifetime<T: Folder>(o_lt: Option<Lifetime>, fld: &mut T) -> Option<Lifetime> {
 610     o_lt.map(|lt| fld.fold_lifetime(lt))
 611 }
 612
 613 pub fn noop_fold_generics<T: Folder>(Generics { ty_params, lifetimes, where_clause }: Generics,
 614                                      fld: &mut T)
 615                                      -> Generics {
 616     Generics {
 617         ty_params: fld.fold_ty_params(ty_params),
 618         lifetimes: fld.fold_lifetime_defs(lifetimes),
 619         where_clause: fld.fold_where_clause(where_clause),
 620     }
 621 }
 622
 623 pub fn noop_fold_where_clause<T: Folder>(WhereClause { id, predicates }: WhereClause,
 624                                          fld: &mut T)
 625                                          -> WhereClause {
 626     WhereClause {
 627         id: fld.new_id(id),
 628         predicates: predicates.move_map(|predicate| fld.fold_where_predicate(predicate)),
 629     }
 630 }
 631
 632 pub fn noop_fold_where_predicate<T: Folder>(pred: WherePredicate, fld: &mut T) -> WherePredicate {
 633     match pred {
 634         hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate{bound_lifetimes,
 635                                                                      bounded_ty,
 636                                                                      bounds,
 637                                                                      span}) => {
 638             hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
 639                 bound_lifetimes: fld.fold_lifetime_defs(bound_lifetimes),
 640                 bounded_ty: fld.fold_ty(bounded_ty),
 641                 bounds: bounds.move_map(|x| fld.fold_ty_param_bound(x)),
 642                 span: fld.new_span(span),
 643             })
 644         }
 645         hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate{lifetime,
 646                                                                        bounds,
 647                                                                        span}) => {
 648             hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate {
 649                 span: fld.new_span(span),
 650                 lifetime: fld.fold_lifetime(lifetime),
 651                 bounds: bounds.move_map(|bound| fld.fold_lifetime(bound)),
 652             })
 653         }
 654         hir::WherePredicate::EqPredicate(hir::WhereEqPredicate{id,
 655                                                                path,
 656                                                                ty,
 657                                                                span}) => {
 658             hir::WherePredicate::EqPredicate(hir::WhereEqPredicate {
 659                 id: fld.new_id(id),
 660                 path: fld.fold_path(path),
 661                 ty: fld.fold_ty(ty),
 662                 span: fld.new_span(span),
 663             })
 664         }
 665     }
 666 }
 667
 668 pub fn noop_fold_variant_data<T: Folder>(vdata: VariantData, fld: &mut T) -> VariantData {
 669     match vdata {
 670         VariantData::Struct(fields, id) => {
 671             VariantData::Struct(fields.move_map(|f| fld.fold_struct_field(f)),
 672                                 fld.new_id(id))
 673         }
 674         VariantData::Tuple(fields, id) => {
 675             VariantData::Tuple(fields.move_map(|f| fld.fold_struct_field(f)),
 676                                fld.new_id(id))
 677         }
 678         VariantData::Unit(id) => VariantData::Unit(fld.new_id(id)),
 679     }
 680 }
 681
 682 pub fn noop_fold_trait_ref<T: Folder>(p: TraitRef, fld: &mut T) -> TraitRef {
 683     let id = fld.new_id(p.ref_id);
 684     let TraitRef {
 685         path,
 686         ref_id: _,
 687     } = p;
 688     hir::TraitRef {
 689         path: fld.fold_path(path),
 690         ref_id: id,
 691     }
 692 }
 693
 694 pub fn noop_fold_poly_trait_ref<T: Folder>(p: PolyTraitRef, fld: &mut T) -> PolyTraitRef {
 695     hir::PolyTraitRef {
 696         bound_lifetimes: fld.fold_lifetime_defs(p.bound_lifetimes),
 697         trait_ref: fld.fold_trait_ref(p.trait_ref),
 698         span: fld.new_span(p.span),
 699     }
 700 }
 701
 702 pub fn noop_fold_struct_field<T: Folder>(f: StructField, fld: &mut T) -> StructField {
 703     let StructField {node: StructField_ {id, kind, ty, attrs}, span} = f;
 704     Spanned {
 705         node: StructField_ {
 706             id: fld.new_id(id),
 707             kind: kind,
 708             ty: fld.fold_ty(ty),
 709             attrs: fold_attrs(attrs, fld),
 710         },
 711         span: fld.new_span(span),
 712     }
 713 }
 714
 715 pub fn noop_fold_field<T: Folder>(Field { name, expr, span }: Field, folder: &mut T) -> Field {
 716     Field {
 717         name: respan(folder.new_span(name.span), folder.fold_name(name.node)),
 718         expr: folder.fold_expr(expr),
 719         span: folder.new_span(span),
 720     }
 721 }
 722
 723 pub fn noop_fold_mt<T: Folder>(MutTy { ty, mutbl }: MutTy, folder: &mut T) -> MutTy {
 724     MutTy {
 725         ty: folder.fold_ty(ty),
 726         mutbl: mutbl,
 727     }
 728 }
 729
 730 pub fn noop_fold_opt_bounds<T: Folder>(b: Option<TyParamBounds>,
 731                                        folder: &mut T)
 732                                        -> Option<TyParamBounds> {
 733     b.map(|bounds| folder.fold_bounds(bounds))
 734 }
 735
 736 fn noop_fold_bounds<T: Folder>(bounds: TyParamBounds, folder: &mut T) -> TyParamBounds {
 737     bounds.move_map(|bound| folder.fold_ty_param_bound(bound))
 738 }
 739
 740 pub fn noop_fold_block<T: Folder>(b: P<Block>, folder: &mut T) -> P<Block> {
 741     b.map(|Block { id, stmts, expr, rules, span }| {
 742         Block {
 743             id: folder.new_id(id),
 744             stmts: stmts.move_map(|s| folder.fold_stmt(s)),
 745             expr: expr.map(|x| folder.fold_expr(x)),
 746             rules: rules,
 747             span: folder.new_span(span),
 748         }
 749     })
 750 }
 751
 752 pub fn noop_fold_item_underscore<T: Folder>(i: Item_, folder: &mut T) -> Item_ {
 753     match i {
 754         ItemExternCrate(string) => ItemExternCrate(string),
 755         ItemUse(view_path) => {
 756             ItemUse(folder.fold_view_path(view_path))
 757         }
 758         ItemStatic(t, m, e) => {
 759             ItemStatic(folder.fold_ty(t), m, folder.fold_expr(e))
 760         }
 761         ItemConst(t, e) => {
 762             ItemConst(folder.fold_ty(t), folder.fold_expr(e))
 763         }
 764         ItemFn(decl, unsafety, constness, abi, generics, body) => {
 765             ItemFn(folder.fold_fn_decl(decl),
 766                    unsafety,
 767                    constness,
 768                    abi,
 769                    folder.fold_generics(generics),
 770                    folder.fold_block(body))
 771         }
 772         ItemMod(m) => ItemMod(folder.fold_mod(m)),
 773         ItemForeignMod(nm) => ItemForeignMod(folder.fold_foreign_mod(nm)),
 774         ItemTy(t, generics) => {
 775             ItemTy(folder.fold_ty(t), folder.fold_generics(generics))
 776         }
 777         ItemEnum(enum_definition, generics) => {
 778             ItemEnum(hir::EnumDef {
 779                          variants: enum_definition.variants.move_map(|x| folder.fold_variant(x)),
 780                      },
 781                      folder.fold_generics(generics))
 782         }
 783         ItemStruct(struct_def, generics) => {
 784             let struct_def = folder.fold_variant_data(struct_def);
 785             ItemStruct(struct_def, folder.fold_generics(generics))
 786         }
 787         ItemDefaultImpl(unsafety, ref trait_ref) => {
 788             ItemDefaultImpl(unsafety, folder.fold_trait_ref((*trait_ref).clone()))
 789         }
 790         ItemImpl(unsafety, polarity, generics, ifce, ty, impl_items) => {
 791             let new_impl_items = impl_items
 792                 .move_map(|item| folder.fold_impl_item(item));
 793             let ifce = match ifce {
 794                 None => None,
 795                 Some(ref trait_ref) => {
 796                     Some(folder.fold_trait_ref((*trait_ref).clone()))
 797                 }
 798             };
 799             ItemImpl(unsafety,
 800                      polarity,
 801                      folder.fold_generics(generics),
 802                      ifce,
 803                      folder.fold_ty(ty),
 804                      new_impl_items)
 805         }
 806         ItemTrait(unsafety, generics, bounds, items) => {
 807             let bounds = folder.fold_bounds(bounds);
 808             let items = items.move_map(|item| folder.fold_trait_item(item));
 809             ItemTrait(unsafety, folder.fold_generics(generics), bounds, items)
 810         }
 811     }
 812 }
 813
 814 pub fn noop_fold_trait_item<T: Folder>(i: TraitItem,
 815                                        folder: &mut T)
 816                                        -> TraitItem {
 817     TraitItem {
 818         id: folder.new_id(i.id),
 819         name: folder.fold_name(i.name),
 820         attrs: fold_attrs(i.attrs, folder),
 821         node: match i.node {
 822             ConstTraitItem(ty, default) => {
 823                 ConstTraitItem(folder.fold_ty(ty), default.map(|x| folder.fold_expr(x)))
 824             }
 825             MethodTraitItem(sig, body) => {
 826                 MethodTraitItem(noop_fold_method_sig(sig, folder),
 827                                 body.map(|x| folder.fold_block(x)))
 828             }
 829             TypeTraitItem(bounds, default) => {
 830                 TypeTraitItem(folder.fold_bounds(bounds),
 831                               default.map(|x| folder.fold_ty(x)))
 832             }
 833         },
 834         span: folder.new_span(i.span),
 835     }
 836 }
 837
 838 pub fn noop_fold_impl_item<T: Folder>(i: ImplItem, folder: &mut T) -> ImplItem {
 839     ImplItem {
 840         id: folder.new_id(i.id),
 841         name: folder.fold_name(i.name),
 842         attrs: fold_attrs(i.attrs, folder),
 843         vis: i.vis,
 844         node: match i.node {
 845             ImplItemKind::Const(ty, expr) => {
 846                 ImplItemKind::Const(folder.fold_ty(ty), folder.fold_expr(expr))
 847             }
 848             ImplItemKind::Method(sig, body) => {
 849                 ImplItemKind::Method(noop_fold_method_sig(sig, folder), folder.fold_block(body))
 850             }
 851             ImplItemKind::Type(ty) => ImplItemKind::Type(folder.fold_ty(ty)),
 852         },
 853         span: folder.new_span(i.span),
 854     }
 855 }
 856
 857 pub fn noop_fold_mod<T: Folder>(Mod { inner, item_ids }: Mod, folder: &mut T) -> Mod {
 858     Mod {
 859         inner: folder.new_span(inner),
 860         item_ids: item_ids.move_map(|x| folder.fold_item_id(x)),
 861     }
 862 }
 863
 864 pub fn noop_fold_crate<T: Folder>(Crate { module, attrs, config, span,
 865                                           exported_macros, items }: Crate,
 866                                   folder: &mut T)
 867                                   -> Crate {
 868     let config = folder.fold_meta_items(config);
 869
 870     let crate_mod = folder.fold_item(hir::Item {
 871         name: token::special_idents::invalid.name,
 872         attrs: attrs,
 873         id: DUMMY_NODE_ID,
 874         vis: hir::Public,
 875         span: span,
 876         node: hir::ItemMod(module),
 877     });
 878
 879     let (module, attrs, span) = match crate_mod {
 880         hir::Item { attrs, span, node, .. } => {
 881             match node {
 882                 hir::ItemMod(m) => (m, attrs, span),
 883                 _ => panic!("fold converted a module to not a module"),
 884             }
 885         }
 886     };
 887
 888     let items = items.into_iter()
 889                      .map(|(id, item)| (id, folder.fold_item(item)))
 890                      .collect();
 891
 892     Crate {
 893         module: module,
 894         attrs: attrs,
 895         config: config,
 896         span: span,
 897         exported_macros: exported_macros,
 898         items: items,
 899     }
 900 }
 901
 902 pub fn noop_fold_item_id<T: Folder>(i: ItemId, folder: &mut T) -> ItemId {
 903     let id = folder.map_id(i.id);
 904     ItemId { id: id }
 905 }
 906
 907 // fold one item into one item
 908 pub fn noop_fold_item<T: Folder>(item: Item, folder: &mut T) -> Item {
 909     let Item { id, name, attrs, node, vis, span } = item;
 910     let id = folder.new_id(id);
 911     let node = folder.fold_item_underscore(node);
 912     // FIXME: we should update the impl_pretty_name, but it uses pretty printing.
 913     // let ident = match node {
 914     //     // The node may have changed, recompute the "pretty" impl name.
 915     //     ItemImpl(_, _, _, ref maybe_trait, ref ty, _) => {
 916     //         impl_pretty_name(maybe_trait, Some(&**ty))
 917     //     }
 918     //     _ => ident
 919     // };
 920
 921     Item {
 922         id: id,
 923         name: folder.fold_name(name),
 924         attrs: fold_attrs(attrs, folder),
 925         node: node,
 926         vis: vis,
 927         span: folder.new_span(span),
 928     }
 929 }
 930
 931 pub fn noop_fold_foreign_item<T: Folder>(ni: ForeignItem, folder: &mut T) -> ForeignItem {
 932     ForeignItem {
 933         id: folder.new_id(ni.id),
 934         name: folder.fold_name(ni.name),
 935         attrs: fold_attrs(ni.attrs, folder),
 936         node: match ni.node {
 937             ForeignItemFn(fdec, generics) => {
 938                 ForeignItemFn(folder.fold_fn_decl(fdec), folder.fold_generics(generics))
 939             }
 940             ForeignItemStatic(t, m) => {
 941                 ForeignItemStatic(folder.fold_ty(t), m)
 942             }
 943         },
 944         vis: ni.vis,
 945         span: folder.new_span(ni.span),
 946     }
 947 }
 948
 949 pub fn noop_fold_method_sig<T: Folder>(sig: MethodSig, folder: &mut T) -> MethodSig {
 950     MethodSig {
 951         generics: folder.fold_generics(sig.generics),
 952         abi: sig.abi,
 953         explicit_self: folder.fold_explicit_self(sig.explicit_self),
 954         unsafety: sig.unsafety,
 955         constness: sig.constness,
 956         decl: folder.fold_fn_decl(sig.decl),
 957     }
 958 }
 959
 960 pub fn noop_fold_pat<T: Folder>(p: P<Pat>, folder: &mut T) -> P<Pat> {
 961     p.map(|Pat { id, node, span }| {
 962         Pat {
 963             id: folder.new_id(id),
 964             node: match node {
 965                 PatKind::Wild => PatKind::Wild,
 966                 PatKind::Ident(binding_mode, pth1, sub) => {
 967                     PatKind::Ident(binding_mode,
 968                              Spanned {
 969                                  span: folder.new_span(pth1.span),
 970                                  node: folder.fold_ident(pth1.node),
 971                              },
 972                              sub.map(|x| folder.fold_pat(x)))
 973                 }
 974                 PatKind::Lit(e) => PatKind::Lit(folder.fold_expr(e)),
 975                 PatKind::TupleStruct(pth, pats) => {
 976                     PatKind::TupleStruct(folder.fold_path(pth),
 977                             pats.map(|pats| pats.move_map(|x| folder.fold_pat(x))))
 978                 }
 979                 PatKind::Path(pth) => {
 980                     PatKind::Path(folder.fold_path(pth))
 981                 }
 982                 PatKind::QPath(qself, pth) => {
 983                     let qself = QSelf { ty: folder.fold_ty(qself.ty), ..qself };
 984                     PatKind::QPath(qself, folder.fold_path(pth))
 985                 }
 986                 PatKind::Struct(pth, fields, etc) => {
 987                     let pth = folder.fold_path(pth);
 988                     let fs = fields.move_map(|f| {
 989                         Spanned {
 990                             span: folder.new_span(f.span),
 991                             node: hir::FieldPat {
 992                                 name: f.node.name,
 993                                 pat: folder.fold_pat(f.node.pat),
 994                                 is_shorthand: f.node.is_shorthand,
 995                             },
 996                         }
 997                     });
 998                     PatKind::Struct(pth, fs, etc)
 999                 }
1000                 PatKind::Tup(elts) => PatKind::Tup(elts.move_map(|x| folder.fold_pat(x))),
1001                 PatKind::Box(inner) => PatKind::Box(folder.fold_pat(inner)),
1002                 PatKind::Ref(inner, mutbl) => PatKind::Ref(folder.fold_pat(inner), mutbl),
1003                 PatKind::Range(e1, e2) => {
1004                     PatKind::Range(folder.fold_expr(e1), folder.fold_expr(e2))
1005                 }
1006                 PatKind::Vec(before, slice, after) => {
1007                     PatKind::Vec(before.move_map(|x| folder.fold_pat(x)),
1008                            slice.map(|x| folder.fold_pat(x)),
1009                            after.move_map(|x| folder.fold_pat(x)))
1010                 }
1011             },
1012             span: folder.new_span(span),
1013         }
1014     })
1015 }
1016
1017 pub fn noop_fold_expr<T: Folder>(Expr { id, node, span, attrs }: Expr, folder: &mut T) -> Expr {
1018     Expr {
1019         id: folder.new_id(id),
1020         node: match node {
1021             ExprBox(e) => {
1022                 ExprBox(folder.fold_expr(e))
1023             }
1024             ExprVec(exprs) => {
1025                 ExprVec(exprs.move_map(|x| folder.fold_expr(x)))
1026             }
1027             ExprRepeat(expr, count) => {
1028                 ExprRepeat(folder.fold_expr(expr), folder.fold_expr(count))
1029             }
1030             ExprTup(elts) => ExprTup(elts.move_map(|x| folder.fold_expr(x))),
1031             ExprCall(f, args) => {
1032                 ExprCall(folder.fold_expr(f), args.move_map(|x| folder.fold_expr(x)))
1033             }
1034             ExprMethodCall(name, tps, args) => {
1035                 ExprMethodCall(respan(folder.new_span(name.span), folder.fold_name(name.node)),
1036                                tps.move_map(|x| folder.fold_ty(x)),
1037                                args.move_map(|x| folder.fold_expr(x)))
1038             }
1039             ExprBinary(binop, lhs, rhs) => {
1040                 ExprBinary(binop, folder.fold_expr(lhs), folder.fold_expr(rhs))
1041             }
1042             ExprUnary(binop, ohs) => {
1043                 ExprUnary(binop, folder.fold_expr(ohs))
1044             }
1045             ExprLit(l) => ExprLit(l),
1046             ExprCast(expr, ty) => {
1047                 ExprCast(folder.fold_expr(expr), folder.fold_ty(ty))
1048             }
1049             ExprType(expr, ty) => {
1050                 ExprType(folder.fold_expr(expr), folder.fold_ty(ty))
1051             }
1052             ExprAddrOf(m, ohs) => ExprAddrOf(m, folder.fold_expr(ohs)),
1053             ExprIf(cond, tr, fl) => {
1054                 ExprIf(folder.fold_expr(cond),
1055                        folder.fold_block(tr),
1056                        fl.map(|x| folder.fold_expr(x)))
1057             }
1058             ExprWhile(cond, body, opt_ident) => {
1059                 ExprWhile(folder.fold_expr(cond),
1060                           folder.fold_block(body),
1061                           opt_ident.map(|i| folder.fold_ident(i)))
1062             }
1063             ExprLoop(body, opt_ident) => {
1064                 ExprLoop(folder.fold_block(body),
1065                          opt_ident.map(|i| folder.fold_ident(i)))
1066             }
1067             ExprMatch(expr, arms, source) => {
1068                 ExprMatch(folder.fold_expr(expr),
1069                           arms.move_map(|x| folder.fold_arm(x)),
1070                           source)
1071             }
1072             ExprClosure(capture_clause, decl, body) => {
1073                 ExprClosure(capture_clause,
1074                             folder.fold_fn_decl(decl),
1075                             folder.fold_block(body))
1076             }
1077             ExprBlock(blk) => ExprBlock(folder.fold_block(blk)),
1078             ExprAssign(el, er) => {
1079                 ExprAssign(folder.fold_expr(el), folder.fold_expr(er))
1080             }
1081             ExprAssignOp(op, el, er) => {
1082                 ExprAssignOp(op, folder.fold_expr(el), folder.fold_expr(er))
1083             }
1084             ExprField(el, name) => {
1085                 ExprField(folder.fold_expr(el),
1086                           respan(folder.new_span(name.span), folder.fold_name(name.node)))
1087             }
1088             ExprTupField(el, index) => {
1089                 ExprTupField(folder.fold_expr(el),
1090                              respan(folder.new_span(index.span), folder.fold_usize(index.node)))
1091             }
1092             ExprIndex(el, er) => {
1093                 ExprIndex(folder.fold_expr(el), folder.fold_expr(er))
1094             }
1095             ExprRange(e1, e2) => {
1096                 ExprRange(e1.map(|x| folder.fold_expr(x)),
1097                           e2.map(|x| folder.fold_expr(x)))
1098             }
1099             ExprPath(qself, path) => {
1100                 let qself = qself.map(|QSelf { ty, position }| {
1101                     QSelf {
1102                         ty: folder.fold_ty(ty),
1103                         position: position,
1104                     }
1105                 });
1106                 ExprPath(qself, folder.fold_path(path))
1107             }
1108             ExprBreak(opt_ident) => ExprBreak(opt_ident.map(|label| {
1109                 respan(folder.new_span(label.span), folder.fold_ident(label.node))
1110             })),
1111             ExprAgain(opt_ident) => ExprAgain(opt_ident.map(|label| {
1112                 respan(folder.new_span(label.span), folder.fold_ident(label.node))
1113             })),
1114             ExprRet(e) => ExprRet(e.map(|x| folder.fold_expr(x))),
1115             ExprInlineAsm(InlineAsm {
1116                 inputs,
1117                 outputs,
1118                 asm,
1119                 asm_str_style,
1120                 clobbers,
1121                 volatile,
1122                 alignstack,
1123                 dialect,
1124                 expn_id,
1125             }) => ExprInlineAsm(InlineAsm {
1126                 inputs: inputs.move_map(|(c, input)| (c, folder.fold_expr(input))),
1127                 outputs: outputs.move_map(|out| {
1128                     InlineAsmOutput {
1129                         constraint: out.constraint,
1130                         expr: folder.fold_expr(out.expr),
1131                         is_rw: out.is_rw,
1132                         is_indirect: out.is_indirect,
1133                     }
1134                 }),
1135                 asm: asm,
1136                 asm_str_style: asm_str_style,
1137                 clobbers: clobbers,
1138                 volatile: volatile,
1139                 alignstack: alignstack,
1140                 dialect: dialect,
1141                 expn_id: expn_id,
1142             }),
1143             ExprStruct(path, fields, maybe_expr) => {
1144                 ExprStruct(folder.fold_path(path),
1145                            fields.move_map(|x| folder.fold_field(x)),
1146                            maybe_expr.map(|x| folder.fold_expr(x)))
1147             }
1148         },
1149         span: folder.new_span(span),
1150         attrs: attrs.map_thin_attrs(|attrs| fold_attrs(attrs.into(), folder).into()),
1151     }
1152 }
1153
1154 pub fn noop_fold_stmt<T: Folder>(stmt: Stmt, folder: &mut T) -> Stmt {
1155     let span = folder.new_span(stmt.span);
1156     match stmt.node {
1157         StmtDecl(d, id) => {
1158             let id = folder.new_id(id);
1159             Spanned {
1160                 node: StmtDecl(folder.fold_decl(d), id),
1161                 span: span
1162             }
1163         }
1164         StmtExpr(e, id) => {
1165             let id = folder.new_id(id);
1166             Spanned {
1167                 node: StmtExpr(folder.fold_expr(e), id),
1168                 span: span,
1169             }
1170         }
1171         StmtSemi(e, id) => {
1172             let id = folder.new_id(id);
1173             Spanned {
1174                 node: StmtSemi(folder.fold_expr(e), id),
1175                 span: span,
1176             }
1177         }
1178     }
1179 }