src/libsyntax/fold.rs

   1 // Copyright 2012-2014 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 AST->AST fold; it accepts an AST piece,
  12 //! and returns a piece of the same type. So, for instance, macro
  13 //! expansion is a Folder that walks over an AST and produces another
  14 //! AST.
  15 //!
  16 //! Note: using a Folder (other than the MacroExpander Folder) on
  17 //! an AST before macro expansion is probably a bad idea. For instance,
  18 //! a folder renaming item names in a module will miss all of those
  19 //! that are created by the expansion of a macro.
  20
  21 use ast::*;
  22 use ast;
  23 use syntax_pos::Span;
  24 use source_map::{Spanned, respan};
  25 use parse::token::{self, Token};
  26 use ptr::P;
  27 use OneVector;
  28 use symbol::keywords;
  29 use ThinVec;
  30 use tokenstream::*;
  31 use util::move_map::MoveMap;
  32
  33 use rustc_data_structures::sync::Lrc;
  34 use rustc_data_structures::small_vec::ExpectOne;
  35
  36 pub trait Folder : Sized {
  37     // Any additions to this trait should happen in form
  38     // of a call to a public `noop_*` function that only calls
  39     // out to the folder again, not other `noop_*` functions.
  40     //
  41     // This is a necessary API workaround to the problem of not
  42     // being able to call out to the super default method
  43     // in an overridden default method.
  44
  45     fn fold_crate(&mut self, c: Crate) -> Crate {
  46         noop_fold_crate(c, self)
  47     }
  48
  49     fn fold_meta_items(&mut self, meta_items: Vec<MetaItem>) -> Vec<MetaItem> {
  50         noop_fold_meta_items(meta_items, self)
  51     }
  52
  53     fn fold_meta_list_item(&mut self, list_item: NestedMetaItem) -> NestedMetaItem {
  54         noop_fold_meta_list_item(list_item, self)
  55     }
  56
  57     fn fold_meta_item(&mut self, meta_item: MetaItem) -> MetaItem {
  58         noop_fold_meta_item(meta_item, self)
  59     }
  60
  61     fn fold_use_tree(&mut self, use_tree: UseTree) -> UseTree {
  62         noop_fold_use_tree(use_tree, self)
  63     }
  64
  65     fn fold_foreign_item(&mut self, ni: ForeignItem) -> OneVector<ForeignItem> {
  66         noop_fold_foreign_item(ni, self)
  67     }
  68
  69     fn fold_foreign_item_simple(&mut self, ni: ForeignItem) -> ForeignItem {
  70         noop_fold_foreign_item_simple(ni, self)
  71     }
  72
  73     fn fold_item(&mut self, i: P<Item>) -> OneVector<P<Item>> {
  74         noop_fold_item(i, self)
  75     }
  76
  77     fn fold_item_simple(&mut self, i: Item) -> Item {
  78         noop_fold_item_simple(i, self)
  79     }
  80
  81     fn fold_fn_header(&mut self, header: FnHeader) -> FnHeader {
  82         noop_fold_fn_header(header, self)
  83     }
  84
  85     fn fold_struct_field(&mut self, sf: StructField) -> StructField {
  86         noop_fold_struct_field(sf, self)
  87     }
  88
  89     fn fold_item_kind(&mut self, i: ItemKind) -> ItemKind {
  90         noop_fold_item_kind(i, self)
  91     }
  92
  93     fn fold_trait_item(&mut self, i: TraitItem) -> OneVector<TraitItem> {
  94         noop_fold_trait_item(i, self)
  95     }
  96
  97     fn fold_impl_item(&mut self, i: ImplItem) -> OneVector<ImplItem> {
  98         noop_fold_impl_item(i, self)
  99     }
 100
 101     fn fold_fn_decl(&mut self, d: P<FnDecl>) -> P<FnDecl> {
 102         noop_fold_fn_decl(d, self)
 103     }
 104
 105     fn fold_asyncness(&mut self, a: IsAsync) -> IsAsync {
 106         noop_fold_asyncness(a, self)
 107     }
 108
 109     fn fold_block(&mut self, b: P<Block>) -> P<Block> {
 110         noop_fold_block(b, self)
 111     }
 112
 113     fn fold_stmt(&mut self, s: Stmt) -> OneVector<Stmt> {
 114         noop_fold_stmt(s, self)
 115     }
 116
 117     fn fold_arm(&mut self, a: Arm) -> Arm {
 118         noop_fold_arm(a, self)
 119     }
 120
 121     fn fold_pat(&mut self, p: P<Pat>) -> P<Pat> {
 122         noop_fold_pat(p, self)
 123     }
 124
 125     fn fold_anon_const(&mut self, c: AnonConst) -> AnonConst {
 126         noop_fold_anon_const(c, self)
 127     }
 128
 129     fn fold_expr(&mut self, e: P<Expr>) -> P<Expr> {
 130         e.map(|e| noop_fold_expr(e, self))
 131     }
 132
 133     fn fold_range_end(&mut self, re: RangeEnd) -> RangeEnd {
 134         noop_fold_range_end(re, self)
 135     }
 136
 137     fn fold_opt_expr(&mut self, e: P<Expr>) -> Option<P<Expr>> {
 138         noop_fold_opt_expr(e, self)
 139     }
 140
 141     fn fold_exprs(&mut self, es: Vec<P<Expr>>) -> Vec<P<Expr>> {
 142         noop_fold_exprs(es, self)
 143     }
 144
 145     fn fold_generic_arg(&mut self, arg: GenericArg) -> GenericArg {
 146         match arg {
 147             GenericArg::Lifetime(lt) => GenericArg::Lifetime(self.fold_lifetime(lt)),
 148             GenericArg::Type(ty) => GenericArg::Type(self.fold_ty(ty)),
 149         }
 150     }
 151
 152     fn fold_ty(&mut self, t: P<Ty>) -> P<Ty> {
 153         noop_fold_ty(t, self)
 154     }
 155
 156     fn fold_lifetime(&mut self, l: Lifetime) -> Lifetime {
 157         noop_fold_lifetime(l, self)
 158     }
 159
 160     fn fold_ty_binding(&mut self, t: TypeBinding) -> TypeBinding {
 161         noop_fold_ty_binding(t, self)
 162     }
 163
 164     fn fold_mod(&mut self, m: Mod) -> Mod {
 165         noop_fold_mod(m, self)
 166     }
 167
 168     fn fold_foreign_mod(&mut self, nm: ForeignMod) -> ForeignMod {
 169         noop_fold_foreign_mod(nm, self)
 170     }
 171
 172     fn fold_global_asm(&mut self, ga: P<GlobalAsm>) -> P<GlobalAsm> {
 173         noop_fold_global_asm(ga, self)
 174     }
 175
 176     fn fold_variant(&mut self, v: Variant) -> Variant {
 177         noop_fold_variant(v, self)
 178     }
 179
 180     fn fold_ident(&mut self, i: Ident) -> Ident {
 181         noop_fold_ident(i, self)
 182     }
 183
 184     fn fold_usize(&mut self, i: usize) -> usize {
 185         noop_fold_usize(i, self)
 186     }
 187
 188     fn fold_path(&mut self, p: Path) -> Path {
 189         noop_fold_path(p, self)
 190     }
 191
 192     fn fold_qpath(&mut self, qs: Option<QSelf>, p: Path) -> (Option<QSelf>, Path) {
 193         noop_fold_qpath(qs, p, self)
 194     }
 195
 196     fn fold_generic_args(&mut self, p: GenericArgs) -> GenericArgs {
 197         noop_fold_generic_args(p, self)
 198     }
 199
 200     fn fold_angle_bracketed_parameter_data(&mut self, p: AngleBracketedArgs)
 201                                            -> AngleBracketedArgs
 202     {
 203         noop_fold_angle_bracketed_parameter_data(p, self)
 204     }
 205
 206     fn fold_parenthesized_parameter_data(&mut self, p: ParenthesisedArgs)
 207                                          -> ParenthesisedArgs
 208     {
 209         noop_fold_parenthesized_parameter_data(p, self)
 210     }
 211
 212     fn fold_local(&mut self, l: P<Local>) -> P<Local> {
 213         noop_fold_local(l, self)
 214     }
 215
 216     fn fold_mac(&mut self, _mac: Mac) -> Mac {
 217         panic!("fold_mac disabled by default");
 218         // NB: see note about macros above.
 219         // if you really want a folder that
 220         // works on macros, use this
 221         // definition in your trait impl:
 222         // fold::noop_fold_mac(_mac, self)
 223     }
 224
 225     fn fold_macro_def(&mut self, def: MacroDef) -> MacroDef {
 226         noop_fold_macro_def(def, self)
 227     }
 228
 229     fn fold_label(&mut self, label: Label) -> Label {
 230         noop_fold_label(label, self)
 231     }
 232
 233     fn fold_attribute(&mut self, at: Attribute) -> Option<Attribute> {
 234         noop_fold_attribute(at, self)
 235     }
 236
 237     fn fold_arg(&mut self, a: Arg) -> Arg {
 238         noop_fold_arg(a, self)
 239     }
 240
 241     fn fold_generics(&mut self, generics: Generics) -> Generics {
 242         noop_fold_generics(generics, self)
 243     }
 244
 245     fn fold_trait_ref(&mut self, p: TraitRef) -> TraitRef {
 246         noop_fold_trait_ref(p, self)
 247     }
 248
 249     fn fold_poly_trait_ref(&mut self, p: PolyTraitRef) -> PolyTraitRef {
 250         noop_fold_poly_trait_ref(p, self)
 251     }
 252
 253     fn fold_variant_data(&mut self, vdata: VariantData) -> VariantData {
 254         noop_fold_variant_data(vdata, self)
 255     }
 256
 257     fn fold_generic_param(&mut self, param: GenericParam) -> GenericParam {
 258         noop_fold_generic_param(param, self)
 259     }
 260
 261     fn fold_generic_params(&mut self, params: Vec<GenericParam>) -> Vec<GenericParam> {
 262         noop_fold_generic_params(params, self)
 263     }
 264
 265     fn fold_tt(&mut self, tt: TokenTree) -> TokenTree {
 266         noop_fold_tt(tt, self)
 267     }
 268
 269     fn fold_tts(&mut self, tts: TokenStream) -> TokenStream {
 270         noop_fold_tts(tts, self)
 271     }
 272
 273     fn fold_token(&mut self, t: token::Token) -> token::Token {
 274         noop_fold_token(t, self)
 275     }
 276
 277     fn fold_interpolated(&mut self, nt: token::Nonterminal) -> token::Nonterminal {
 278         noop_fold_interpolated(nt, self)
 279     }
 280
 281     fn fold_opt_bounds(&mut self, b: Option<GenericBounds>) -> Option<GenericBounds> {
 282         noop_fold_opt_bounds(b, self)
 283     }
 284
 285     fn fold_bounds(&mut self, b: GenericBounds) -> GenericBounds {
 286         noop_fold_bounds(b, self)
 287     }
 288
 289     fn fold_param_bound(&mut self, tpb: GenericBound) -> GenericBound {
 290         noop_fold_param_bound(tpb, self)
 291     }
 292
 293     fn fold_mt(&mut self, mt: MutTy) -> MutTy {
 294         noop_fold_mt(mt, self)
 295     }
 296
 297     fn fold_field(&mut self, field: Field) -> Field {
 298         noop_fold_field(field, self)
 299     }
 300
 301     fn fold_where_clause(&mut self, where_clause: WhereClause)
 302                          -> WhereClause {
 303         noop_fold_where_clause(where_clause, self)
 304     }
 305
 306     fn fold_where_predicate(&mut self, where_predicate: WherePredicate)
 307                             -> WherePredicate {
 308         noop_fold_where_predicate(where_predicate, self)
 309     }
 310
 311     fn fold_vis(&mut self, vis: Visibility) -> Visibility {
 312         noop_fold_vis(vis, self)
 313     }
 314
 315     fn new_id(&mut self, i: NodeId) -> NodeId {
 316         i
 317     }
 318
 319     fn new_span(&mut self, sp: Span) -> Span {
 320         sp
 321     }
 322 }
 323
 324 pub fn noop_fold_meta_items<T: Folder>(meta_items: Vec<MetaItem>, fld: &mut T) -> Vec<MetaItem> {
 325     meta_items.move_map(|x| fld.fold_meta_item(x))
 326 }
 327
 328 pub fn noop_fold_use_tree<T: Folder>(use_tree: UseTree, fld: &mut T) -> UseTree {
 329     UseTree {
 330         span: fld.new_span(use_tree.span),
 331         prefix: fld.fold_path(use_tree.prefix),
 332         kind: match use_tree.kind {
 333             UseTreeKind::Simple(rename, id1, id2) =>
 334                 UseTreeKind::Simple(rename.map(|ident| fld.fold_ident(ident)),
 335                                     fld.new_id(id1), fld.new_id(id2)),
 336             UseTreeKind::Glob => UseTreeKind::Glob,
 337             UseTreeKind::Nested(items) => UseTreeKind::Nested(items.move_map(|(tree, id)| {
 338                 (fld.fold_use_tree(tree), fld.new_id(id))
 339             })),
 340         },
 341     }
 342 }
 343
 344 pub fn fold_attrs<T: Folder>(attrs: Vec<Attribute>, fld: &mut T) -> Vec<Attribute> {
 345     attrs.move_flat_map(|x| fld.fold_attribute(x))
 346 }
 347
 348 pub fn fold_thin_attrs<T: Folder>(attrs: ThinVec<Attribute>, fld: &mut T) -> ThinVec<Attribute> {
 349     fold_attrs(attrs.into(), fld).into()
 350 }
 351
 352 pub fn noop_fold_arm<T: Folder>(Arm {attrs, pats, guard, body}: Arm,
 353     fld: &mut T) -> Arm {
 354     Arm {
 355         attrs: fold_attrs(attrs, fld),
 356         pats: pats.move_map(|x| fld.fold_pat(x)),
 357         guard: guard.map(|x| fld.fold_expr(x)),
 358         body: fld.fold_expr(body),
 359     }
 360 }
 361
 362 pub fn noop_fold_ty_binding<T: Folder>(b: TypeBinding, fld: &mut T) -> TypeBinding {
 363     TypeBinding {
 364         id: fld.new_id(b.id),
 365         ident: fld.fold_ident(b.ident),
 366         ty: fld.fold_ty(b.ty),
 367         span: fld.new_span(b.span),
 368     }
 369 }
 370
 371 pub fn noop_fold_ty<T: Folder>(t: P<Ty>, fld: &mut T) -> P<Ty> {
 372     t.map(|Ty {id, node, span}| Ty {
 373         id: fld.new_id(id),
 374         node: match node {
 375             TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err => node,
 376             TyKind::Slice(ty) => TyKind::Slice(fld.fold_ty(ty)),
 377             TyKind::Ptr(mt) => TyKind::Ptr(fld.fold_mt(mt)),
 378             TyKind::Rptr(region, mt) => {
 379                 TyKind::Rptr(region.map(|lt| noop_fold_lifetime(lt, fld)), fld.fold_mt(mt))
 380             }
 381             TyKind::BareFn(f) => {
 382                 TyKind::BareFn(f.map(|BareFnTy {generic_params, unsafety, abi, decl}| BareFnTy {
 383                     generic_params: fld.fold_generic_params(generic_params),
 384                     unsafety,
 385                     abi,
 386                     decl: fld.fold_fn_decl(decl)
 387                 }))
 388             }
 389             TyKind::Never => node,
 390             TyKind::Tup(tys) => TyKind::Tup(tys.move_map(|ty| fld.fold_ty(ty))),
 391             TyKind::Paren(ty) => TyKind::Paren(fld.fold_ty(ty)),
 392             TyKind::Path(qself, path) => {
 393                 let (qself, path) = fld.fold_qpath(qself, path);
 394                 TyKind::Path(qself, path)
 395             }
 396             TyKind::Array(ty, length) => {
 397                 TyKind::Array(fld.fold_ty(ty), fld.fold_anon_const(length))
 398             }
 399             TyKind::Typeof(expr) => {
 400                 TyKind::Typeof(fld.fold_anon_const(expr))
 401             }
 402             TyKind::TraitObject(bounds, syntax) => {
 403                 TyKind::TraitObject(bounds.move_map(|b| fld.fold_param_bound(b)), syntax)
 404             }
 405             TyKind::ImplTrait(id, bounds) => {
 406                 TyKind::ImplTrait(fld.new_id(id), bounds.move_map(|b| fld.fold_param_bound(b)))
 407             }
 408             TyKind::Mac(mac) => {
 409                 TyKind::Mac(fld.fold_mac(mac))
 410             }
 411         },
 412         span: fld.new_span(span)
 413     })
 414 }
 415
 416 pub fn noop_fold_foreign_mod<T: Folder>(ForeignMod {abi, items}: ForeignMod,
 417                                         fld: &mut T) -> ForeignMod {
 418     ForeignMod {
 419         abi,
 420         items: items.move_flat_map(|x| fld.fold_foreign_item(x)),
 421     }
 422 }
 423
 424 pub fn noop_fold_global_asm<T: Folder>(ga: P<GlobalAsm>,
 425                                        _: &mut T) -> P<GlobalAsm> {
 426     ga
 427 }
 428
 429 pub fn noop_fold_variant<T: Folder>(v: Variant, fld: &mut T) -> Variant {
 430     Spanned {
 431         node: Variant_ {
 432             ident: fld.fold_ident(v.node.ident),
 433             attrs: fold_attrs(v.node.attrs, fld),
 434             data: fld.fold_variant_data(v.node.data),
 435             disr_expr: v.node.disr_expr.map(|e| fld.fold_anon_const(e)),
 436         },
 437         span: fld.new_span(v.span),
 438     }
 439 }
 440
 441 pub fn noop_fold_ident<T: Folder>(ident: Ident, fld: &mut T) -> Ident {
 442     Ident::new(ident.name, fld.new_span(ident.span))
 443 }
 444
 445 pub fn noop_fold_usize<T: Folder>(i: usize, _: &mut T) -> usize {
 446     i
 447 }
 448
 449 pub fn noop_fold_path<T: Folder>(Path { segments, span }: Path, fld: &mut T) -> Path {
 450     Path {
 451         segments: segments.move_map(|PathSegment { ident, args }| PathSegment {
 452             ident: fld.fold_ident(ident),
 453             args: args.map(|args| args.map(|args| fld.fold_generic_args(args))),
 454         }),
 455         span: fld.new_span(span)
 456     }
 457 }
 458
 459 pub fn noop_fold_qpath<T: Folder>(qself: Option<QSelf>,
 460                                   path: Path,
 461                                   fld: &mut T) -> (Option<QSelf>, Path) {
 462     let qself = qself.map(|QSelf { ty, path_span, position }| {
 463         QSelf {
 464             ty: fld.fold_ty(ty),
 465             path_span: fld.new_span(path_span),
 466             position,
 467         }
 468     });
 469     (qself, fld.fold_path(path))
 470 }
 471
 472 pub fn noop_fold_generic_args<T: Folder>(generic_args: GenericArgs, fld: &mut T) -> GenericArgs
 473 {
 474     match generic_args {
 475         GenericArgs::AngleBracketed(data) => {
 476             GenericArgs::AngleBracketed(fld.fold_angle_bracketed_parameter_data(data))
 477         }
 478         GenericArgs::Parenthesized(data) => {
 479             GenericArgs::Parenthesized(fld.fold_parenthesized_parameter_data(data))
 480         }
 481     }
 482 }
 483
 484 pub fn noop_fold_angle_bracketed_parameter_data<T: Folder>(data: AngleBracketedArgs,
 485                                                            fld: &mut T)
 486                                                            -> AngleBracketedArgs
 487 {
 488     let AngleBracketedArgs { args, bindings, span } = data;
 489     AngleBracketedArgs {
 490         args: args.move_map(|arg| fld.fold_generic_arg(arg)),
 491         bindings: bindings.move_map(|b| fld.fold_ty_binding(b)),
 492         span: fld.new_span(span)
 493     }
 494 }
 495
 496 pub fn noop_fold_parenthesized_parameter_data<T: Folder>(data: ParenthesisedArgs,
 497                                                          fld: &mut T)
 498                                                          -> ParenthesisedArgs
 499 {
 500     let ParenthesisedArgs { inputs, output, span } = data;
 501     ParenthesisedArgs {
 502         inputs: inputs.move_map(|ty| fld.fold_ty(ty)),
 503         output: output.map(|ty| fld.fold_ty(ty)),
 504         span: fld.new_span(span)
 505     }
 506 }
 507
 508 pub fn noop_fold_local<T: Folder>(l: P<Local>, fld: &mut T) -> P<Local> {
 509     l.map(|Local {id, pat, ty, init, span, attrs}| Local {
 510         id: fld.new_id(id),
 511         pat: fld.fold_pat(pat),
 512         ty: ty.map(|t| fld.fold_ty(t)),
 513         init: init.map(|e| fld.fold_expr(e)),
 514         span: fld.new_span(span),
 515         attrs: fold_attrs(attrs.into(), fld).into(),
 516     })
 517 }
 518
 519 pub fn noop_fold_attribute<T: Folder>(attr: Attribute, fld: &mut T) -> Option<Attribute> {
 520     Some(Attribute {
 521         id: attr.id,
 522         style: attr.style,
 523         path: fld.fold_path(attr.path),
 524         tokens: fld.fold_tts(attr.tokens),
 525         is_sugared_doc: attr.is_sugared_doc,
 526         span: fld.new_span(attr.span),
 527     })
 528 }
 529
 530 pub fn noop_fold_mac<T: Folder>(Spanned {node, span}: Mac, fld: &mut T) -> Mac {
 531     Spanned {
 532         node: Mac_ {
 533             tts: fld.fold_tts(node.stream()).into(),
 534             path: fld.fold_path(node.path),
 535             delim: node.delim,
 536         },
 537         span: fld.new_span(span)
 538     }
 539 }
 540
 541 pub fn noop_fold_macro_def<T: Folder>(def: MacroDef, fld: &mut T) -> MacroDef {
 542     MacroDef {
 543         tokens: fld.fold_tts(def.tokens.into()).into(),
 544         legacy: def.legacy,
 545     }
 546 }
 547
 548 pub fn noop_fold_meta_list_item<T: Folder>(li: NestedMetaItem, fld: &mut T)
 549     -> NestedMetaItem {
 550     Spanned {
 551         node: match li.node {
 552             NestedMetaItemKind::MetaItem(mi) =>  {
 553                 NestedMetaItemKind::MetaItem(fld.fold_meta_item(mi))
 554             },
 555             NestedMetaItemKind::Literal(lit) => NestedMetaItemKind::Literal(lit)
 556         },
 557         span: fld.new_span(li.span)
 558     }
 559 }
 560
 561 pub fn noop_fold_meta_item<T: Folder>(mi: MetaItem, fld: &mut T) -> MetaItem {
 562     MetaItem {
 563         ident: mi.ident,
 564         node: match mi.node {
 565             MetaItemKind::Word => MetaItemKind::Word,
 566             MetaItemKind::List(mis) => {
 567                 MetaItemKind::List(mis.move_map(|e| fld.fold_meta_list_item(e)))
 568             },
 569             MetaItemKind::NameValue(s) => MetaItemKind::NameValue(s),
 570         },
 571         span: fld.new_span(mi.span)
 572     }
 573 }
 574
 575 pub fn noop_fold_arg<T: Folder>(Arg {id, pat, ty}: Arg, fld: &mut T) -> Arg {
 576     Arg {
 577         id: fld.new_id(id),
 578         pat: fld.fold_pat(pat),
 579         ty: fld.fold_ty(ty)
 580     }
 581 }
 582
 583 pub fn noop_fold_tt<T: Folder>(tt: TokenTree, fld: &mut T) -> TokenTree {
 584     match tt {
 585         TokenTree::Token(span, tok) =>
 586             TokenTree::Token(fld.new_span(span), fld.fold_token(tok)),
 587         TokenTree::Delimited(span, delimed) => TokenTree::Delimited(fld.new_span(span), Delimited {
 588             tts: fld.fold_tts(delimed.stream()).into(),
 589             delim: delimed.delim,
 590         }),
 591     }
 592 }
 593
 594 pub fn noop_fold_tts<T: Folder>(tts: TokenStream, fld: &mut T) -> TokenStream {
 595     tts.map(|tt| fld.fold_tt(tt))
 596 }
 597
 598 // apply ident folder if it's an ident, apply other folds to interpolated nodes
 599 pub fn noop_fold_token<T: Folder>(t: token::Token, fld: &mut T) -> token::Token {
 600     match t {
 601         token::Ident(id, is_raw) => token::Ident(fld.fold_ident(id), is_raw),
 602         token::Lifetime(id) => token::Lifetime(fld.fold_ident(id)),
 603         token::Interpolated(nt) => {
 604             let nt = match Lrc::try_unwrap(nt) {
 605                 Ok(nt) => nt,
 606                 Err(nt) => (*nt).clone(),
 607             };
 608             Token::interpolated(fld.fold_interpolated(nt.0))
 609         }
 610         _ => t
 611     }
 612 }
 613
 614 /// apply folder to elements of interpolated nodes
 615 //
 616 // NB: this can occur only when applying a fold to partially expanded code, where
 617 // parsed pieces have gotten implanted ito *other* macro invocations. This is relevant
 618 // for macro hygiene, but possibly not elsewhere.
 619 //
 620 // One problem here occurs because the types for fold_item, fold_stmt, etc. allow the
 621 // folder to return *multiple* items; this is a problem for the nodes here, because
 622 // they insist on having exactly one piece. One solution would be to mangle the fold
 623 // trait to include one-to-many and one-to-one versions of these entry points, but that
 624 // would probably confuse a lot of people and help very few. Instead, I'm just going
 625 // to put in dynamic checks. I think the performance impact of this will be pretty much
 626 // nonexistent. The danger is that someone will apply a fold to a partially expanded
 627 // node, and will be confused by the fact that their "fold_item" or "fold_stmt" isn't
 628 // getting called on NtItem or NtStmt nodes. Hopefully they'll wind up reading this
 629 // comment, and doing something appropriate.
 630 //
 631 // BTW, design choice: I considered just changing the type of, e.g., NtItem to contain
 632 // multiple items, but decided against it when I looked at parse_item_or_view_item and
 633 // tried to figure out what I would do with multiple items there....
 634 pub fn noop_fold_interpolated<T: Folder>(nt: token::Nonterminal, fld: &mut T)
 635                                          -> token::Nonterminal {
 636     match nt {
 637         token::NtItem(item) =>
 638             token::NtItem(fld.fold_item(item)
 639                           // this is probably okay, because the only folds likely
 640                           // to peek inside interpolated nodes will be renamings/markings,
 641                           // which map single items to single items
 642                           .expect_one("expected fold to produce exactly one item")),
 643         token::NtBlock(block) => token::NtBlock(fld.fold_block(block)),
 644         token::NtStmt(stmt) =>
 645             token::NtStmt(fld.fold_stmt(stmt)
 646                           // this is probably okay, because the only folds likely
 647                           // to peek inside interpolated nodes will be renamings/markings,
 648                           // which map single items to single items
 649                           .expect_one("expected fold to produce exactly one statement")),
 650         token::NtPat(pat) => token::NtPat(fld.fold_pat(pat)),
 651         token::NtExpr(expr) => token::NtExpr(fld.fold_expr(expr)),
 652         token::NtTy(ty) => token::NtTy(fld.fold_ty(ty)),
 653         token::NtIdent(ident, is_raw) => token::NtIdent(fld.fold_ident(ident), is_raw),
 654         token::NtLifetime(ident) => token::NtLifetime(fld.fold_ident(ident)),
 655         token::NtLiteral(expr) => token::NtLiteral(fld.fold_expr(expr)),
 656         token::NtMeta(meta) => token::NtMeta(fld.fold_meta_item(meta)),
 657         token::NtPath(path) => token::NtPath(fld.fold_path(path)),
 658         token::NtTT(tt) => token::NtTT(fld.fold_tt(tt)),
 659         token::NtArm(arm) => token::NtArm(fld.fold_arm(arm)),
 660         token::NtImplItem(item) =>
 661             token::NtImplItem(fld.fold_impl_item(item)
 662                               .expect_one("expected fold to produce exactly one item")),
 663         token::NtTraitItem(item) =>
 664             token::NtTraitItem(fld.fold_trait_item(item)
 665                                .expect_one("expected fold to produce exactly one item")),
 666         token::NtGenerics(generics) => token::NtGenerics(fld.fold_generics(generics)),
 667         token::NtWhereClause(where_clause) =>
 668             token::NtWhereClause(fld.fold_where_clause(where_clause)),
 669         token::NtArg(arg) => token::NtArg(fld.fold_arg(arg)),
 670         token::NtVis(vis) => token::NtVis(fld.fold_vis(vis)),
 671         token::NtForeignItem(ni) =>
 672             token::NtForeignItem(fld.fold_foreign_item(ni)
 673                                  // see reasoning above
 674                                  .expect_one("expected fold to produce exactly one item")),
 675     }
 676 }
 677
 678 pub fn noop_fold_asyncness<T: Folder>(asyncness: IsAsync, fld: &mut T) -> IsAsync {
 679     match asyncness {
 680         IsAsync::Async { closure_id, return_impl_trait_id } => IsAsync::Async {
 681             closure_id: fld.new_id(closure_id),
 682             return_impl_trait_id: fld.new_id(return_impl_trait_id),
 683         },
 684         IsAsync::NotAsync => IsAsync::NotAsync,
 685     }
 686 }
 687
 688 pub fn noop_fold_fn_decl<T: Folder>(decl: P<FnDecl>, fld: &mut T) -> P<FnDecl> {
 689     decl.map(|FnDecl {inputs, output, variadic}| FnDecl {
 690         inputs: inputs.move_map(|x| fld.fold_arg(x)),
 691         output: match output {
 692             FunctionRetTy::Ty(ty) => FunctionRetTy::Ty(fld.fold_ty(ty)),
 693             FunctionRetTy::Default(span) => FunctionRetTy::Default(fld.new_span(span)),
 694         },
 695         variadic,
 696     })
 697 }
 698
 699 pub fn noop_fold_param_bound<T>(pb: GenericBound, fld: &mut T) -> GenericBound where T: Folder {
 700     match pb {
 701         GenericBound::Trait(ty, modifier) => {
 702             GenericBound::Trait(fld.fold_poly_trait_ref(ty), modifier)
 703         }
 704         GenericBound::Outlives(lifetime) => {
 705             GenericBound::Outlives(noop_fold_lifetime(lifetime, fld))
 706         }
 707     }
 708 }
 709
 710 pub fn noop_fold_generic_param<T: Folder>(param: GenericParam, fld: &mut T) -> GenericParam {
 711     let attrs: Vec<_> = param.attrs.into();
 712     GenericParam {
 713         ident: fld.fold_ident(param.ident),
 714         id: fld.new_id(param.id),
 715         attrs: attrs.into_iter()
 716                     .flat_map(|x| fld.fold_attribute(x).into_iter())
 717                     .collect::<Vec<_>>()
 718                     .into(),
 719         bounds: param.bounds.move_map(|l| noop_fold_param_bound(l, fld)),
 720         kind: match param.kind {
 721             GenericParamKind::Lifetime => GenericParamKind::Lifetime,
 722             GenericParamKind::Type { default } => GenericParamKind::Type {
 723                 default: default.map(|ty| fld.fold_ty(ty))
 724             }
 725         }
 726     }
 727 }
 728
 729 pub fn noop_fold_generic_params<T: Folder>(
 730     params: Vec<GenericParam>,
 731     fld: &mut T
 732 ) -> Vec<GenericParam> {
 733     params.move_map(|p| fld.fold_generic_param(p))
 734 }
 735
 736 pub fn noop_fold_label<T: Folder>(label: Label, fld: &mut T) -> Label {
 737     Label {
 738         ident: fld.fold_ident(label.ident),
 739     }
 740 }
 741
 742 fn noop_fold_lifetime<T: Folder>(l: Lifetime, fld: &mut T) -> Lifetime {
 743     Lifetime {
 744         id: fld.new_id(l.id),
 745         ident: fld.fold_ident(l.ident),
 746     }
 747 }
 748
 749 pub fn noop_fold_generics<T: Folder>(Generics { params, where_clause, span }: Generics,
 750                                      fld: &mut T) -> Generics {
 751     Generics {
 752         params: fld.fold_generic_params(params),
 753         where_clause: fld.fold_where_clause(where_clause),
 754         span: fld.new_span(span),
 755     }
 756 }
 757
 758 pub fn noop_fold_where_clause<T: Folder>(
 759                               WhereClause {id, predicates, span}: WhereClause,
 760                               fld: &mut T)
 761                               -> WhereClause {
 762     WhereClause {
 763         id: fld.new_id(id),
 764         predicates: predicates.move_map(|predicate| {
 765             fld.fold_where_predicate(predicate)
 766         }),
 767         span,
 768     }
 769 }
 770
 771 pub fn noop_fold_where_predicate<T: Folder>(
 772                                  pred: WherePredicate,
 773                                  fld: &mut T)
 774                                  -> WherePredicate {
 775     match pred {
 776         ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate{bound_generic_params,
 777                                                                      bounded_ty,
 778                                                                      bounds,
 779                                                                      span}) => {
 780             ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
 781                 bound_generic_params: fld.fold_generic_params(bound_generic_params),
 782                 bounded_ty: fld.fold_ty(bounded_ty),
 783                 bounds: bounds.move_map(|x| fld.fold_param_bound(x)),
 784                 span: fld.new_span(span)
 785             })
 786         }
 787         ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate{lifetime,
 788                                                                        bounds,
 789                                                                        span}) => {
 790             ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
 791                 span: fld.new_span(span),
 792                 lifetime: noop_fold_lifetime(lifetime, fld),
 793                 bounds: bounds.move_map(|bound| noop_fold_param_bound(bound, fld))
 794             })
 795         }
 796         ast::WherePredicate::EqPredicate(ast::WhereEqPredicate{id,
 797                                                                lhs_ty,
 798                                                                rhs_ty,
 799                                                                span}) => {
 800             ast::WherePredicate::EqPredicate(ast::WhereEqPredicate{
 801                 id: fld.new_id(id),
 802                 lhs_ty: fld.fold_ty(lhs_ty),
 803                 rhs_ty: fld.fold_ty(rhs_ty),
 804                 span: fld.new_span(span)
 805             })
 806         }
 807     }
 808 }
 809
 810 pub fn noop_fold_variant_data<T: Folder>(vdata: VariantData, fld: &mut T) -> VariantData {
 811     match vdata {
 812         ast::VariantData::Struct(fields, id) => {
 813             ast::VariantData::Struct(fields.move_map(|f| fld.fold_struct_field(f)),
 814                                      fld.new_id(id))
 815         }
 816         ast::VariantData::Tuple(fields, id) => {
 817             ast::VariantData::Tuple(fields.move_map(|f| fld.fold_struct_field(f)),
 818                                     fld.new_id(id))
 819         }
 820         ast::VariantData::Unit(id) => ast::VariantData::Unit(fld.new_id(id))
 821     }
 822 }
 823
 824 pub fn noop_fold_trait_ref<T: Folder>(p: TraitRef, fld: &mut T) -> TraitRef {
 825     let id = fld.new_id(p.ref_id);
 826     let TraitRef {
 827         path,
 828         ref_id: _,
 829     } = p;
 830     ast::TraitRef {
 831         path: fld.fold_path(path),
 832         ref_id: id,
 833     }
 834 }
 835
 836 pub fn noop_fold_poly_trait_ref<T: Folder>(p: PolyTraitRef, fld: &mut T) -> PolyTraitRef {
 837     ast::PolyTraitRef {
 838         bound_generic_params: fld.fold_generic_params(p.bound_generic_params),
 839         trait_ref: fld.fold_trait_ref(p.trait_ref),
 840         span: fld.new_span(p.span),
 841     }
 842 }
 843
 844 pub fn noop_fold_struct_field<T: Folder>(f: StructField, fld: &mut T) -> StructField {
 845     StructField {
 846         span: fld.new_span(f.span),
 847         id: fld.new_id(f.id),
 848         ident: f.ident.map(|ident| fld.fold_ident(ident)),
 849         vis: fld.fold_vis(f.vis),
 850         ty: fld.fold_ty(f.ty),
 851         attrs: fold_attrs(f.attrs, fld),
 852     }
 853 }
 854
 855 pub fn noop_fold_field<T: Folder>(f: Field, folder: &mut T) -> Field {
 856     Field {
 857         ident: folder.fold_ident(f.ident),
 858         expr: folder.fold_expr(f.expr),
 859         span: folder.new_span(f.span),
 860         is_shorthand: f.is_shorthand,
 861         attrs: fold_thin_attrs(f.attrs, folder),
 862     }
 863 }
 864
 865 pub fn noop_fold_mt<T: Folder>(MutTy {ty, mutbl}: MutTy, folder: &mut T) -> MutTy {
 866     MutTy {
 867         ty: folder.fold_ty(ty),
 868         mutbl,
 869     }
 870 }
 871
 872 pub fn noop_fold_opt_bounds<T: Folder>(b: Option<GenericBounds>, folder: &mut T)
 873                                        -> Option<GenericBounds> {
 874     b.map(|bounds| folder.fold_bounds(bounds))
 875 }
 876
 877 fn noop_fold_bounds<T: Folder>(bounds: GenericBounds, folder: &mut T)
 878                           -> GenericBounds {
 879     bounds.move_map(|bound| folder.fold_param_bound(bound))
 880 }
 881
 882 pub fn noop_fold_block<T: Folder>(b: P<Block>, folder: &mut T) -> P<Block> {
 883     b.map(|Block {id, stmts, rules, span, recovered}| Block {
 884         id: folder.new_id(id),
 885         stmts: stmts.move_flat_map(|s| folder.fold_stmt(s).into_iter()),
 886         rules,
 887         span: folder.new_span(span),
 888         recovered,
 889     })
 890 }
 891
 892 pub fn noop_fold_item_kind<T: Folder>(i: ItemKind, folder: &mut T) -> ItemKind {
 893     match i {
 894         ItemKind::ExternCrate(orig_name) => ItemKind::ExternCrate(orig_name),
 895         ItemKind::Use(use_tree) => {
 896             ItemKind::Use(use_tree.map(|tree| folder.fold_use_tree(tree)))
 897         }
 898         ItemKind::Static(t, m, e) => {
 899             ItemKind::Static(folder.fold_ty(t), m, folder.fold_expr(e))
 900         }
 901         ItemKind::Const(t, e) => {
 902             ItemKind::Const(folder.fold_ty(t), folder.fold_expr(e))
 903         }
 904         ItemKind::Fn(decl, header, generics, body) => {
 905             let generics = folder.fold_generics(generics);
 906             let header = folder.fold_fn_header(header);
 907             let decl = folder.fold_fn_decl(decl);
 908             let body = folder.fold_block(body);
 909             ItemKind::Fn(decl, header, generics, body)
 910         }
 911         ItemKind::Mod(m) => ItemKind::Mod(folder.fold_mod(m)),
 912         ItemKind::ForeignMod(nm) => ItemKind::ForeignMod(folder.fold_foreign_mod(nm)),
 913         ItemKind::GlobalAsm(ga) => ItemKind::GlobalAsm(folder.fold_global_asm(ga)),
 914         ItemKind::Ty(t, generics) => {
 915             ItemKind::Ty(folder.fold_ty(t), folder.fold_generics(generics))
 916         }
 917         ItemKind::Existential(bounds, generics) => ItemKind::Existential(
 918             folder.fold_bounds(bounds),
 919             folder.fold_generics(generics),
 920         ),
 921         ItemKind::Enum(enum_definition, generics) => {
 922             let generics = folder.fold_generics(generics);
 923             let variants = enum_definition.variants.move_map(|x| folder.fold_variant(x));
 924             ItemKind::Enum(ast::EnumDef { variants: variants }, generics)
 925         }
 926         ItemKind::Struct(struct_def, generics) => {
 927             let generics = folder.fold_generics(generics);
 928             ItemKind::Struct(folder.fold_variant_data(struct_def), generics)
 929         }
 930         ItemKind::Union(struct_def, generics) => {
 931             let generics = folder.fold_generics(generics);
 932             ItemKind::Union(folder.fold_variant_data(struct_def), generics)
 933         }
 934         ItemKind::Impl(unsafety,
 935                        polarity,
 936                        defaultness,
 937                        generics,
 938                        ifce,
 939                        ty,
 940                        impl_items) => ItemKind::Impl(
 941             unsafety,
 942             polarity,
 943             defaultness,
 944             folder.fold_generics(generics),
 945             ifce.map(|trait_ref| folder.fold_trait_ref(trait_ref.clone())),
 946             folder.fold_ty(ty),
 947             impl_items.move_flat_map(|item| folder.fold_impl_item(item)),
 948         ),
 949         ItemKind::Trait(is_auto, unsafety, generics, bounds, items) => ItemKind::Trait(
 950             is_auto,
 951             unsafety,
 952             folder.fold_generics(generics),
 953             folder.fold_bounds(bounds),
 954             items.move_flat_map(|item| folder.fold_trait_item(item)),
 955         ),
 956         ItemKind::TraitAlias(generics, bounds) => ItemKind::TraitAlias(
 957             folder.fold_generics(generics),
 958             folder.fold_bounds(bounds)),
 959         ItemKind::Mac(m) => ItemKind::Mac(folder.fold_mac(m)),
 960         ItemKind::MacroDef(def) => ItemKind::MacroDef(folder.fold_macro_def(def)),
 961     }
 962 }
 963
 964 pub fn noop_fold_trait_item<T: Folder>(i: TraitItem, folder: &mut T)
 965                                        -> OneVector<TraitItem> {
 966     smallvec![TraitItem {
 967         id: folder.new_id(i.id),
 968         ident: folder.fold_ident(i.ident),
 969         attrs: fold_attrs(i.attrs, folder),
 970         generics: folder.fold_generics(i.generics),
 971         node: match i.node {
 972             TraitItemKind::Const(ty, default) => {
 973                 TraitItemKind::Const(folder.fold_ty(ty),
 974                                default.map(|x| folder.fold_expr(x)))
 975             }
 976             TraitItemKind::Method(sig, body) => {
 977                 TraitItemKind::Method(noop_fold_method_sig(sig, folder),
 978                                 body.map(|x| folder.fold_block(x)))
 979             }
 980             TraitItemKind::Type(bounds, default) => {
 981                 TraitItemKind::Type(folder.fold_bounds(bounds),
 982                               default.map(|x| folder.fold_ty(x)))
 983             }
 984             ast::TraitItemKind::Macro(mac) => {
 985                 TraitItemKind::Macro(folder.fold_mac(mac))
 986             }
 987         },
 988         span: folder.new_span(i.span),
 989         tokens: i.tokens,
 990     }]
 991 }
 992
 993 pub fn noop_fold_impl_item<T: Folder>(i: ImplItem, folder: &mut T)
 994                                       -> OneVector<ImplItem> {
 995     smallvec![ImplItem {
 996         id: folder.new_id(i.id),
 997         vis: folder.fold_vis(i.vis),
 998         ident: folder.fold_ident(i.ident),
 999         attrs: fold_attrs(i.attrs, folder),
1000         generics: folder.fold_generics(i.generics),
1001         defaultness: i.defaultness,
1002         node: match i.node  {
1003             ast::ImplItemKind::Const(ty, expr) => {
1004                 ast::ImplItemKind::Const(folder.fold_ty(ty), folder.fold_expr(expr))
1005             }
1006             ast::ImplItemKind::Method(sig, body) => {
1007                 ast::ImplItemKind::Method(noop_fold_method_sig(sig, folder),
1008                                folder.fold_block(body))
1009             }
1010             ast::ImplItemKind::Type(ty) => ast::ImplItemKind::Type(folder.fold_ty(ty)),
1011             ast::ImplItemKind::Existential(bounds) => {
1012                 ast::ImplItemKind::Existential(folder.fold_bounds(bounds))
1013             },
1014             ast::ImplItemKind::Macro(mac) => ast::ImplItemKind::Macro(folder.fold_mac(mac))
1015         },
1016         span: folder.new_span(i.span),
1017         tokens: i.tokens,
1018     }]
1019 }
1020
1021 pub fn noop_fold_fn_header<T: Folder>(mut header: FnHeader, folder: &mut T) -> FnHeader {
1022     header.asyncness = folder.fold_asyncness(header.asyncness);
1023     header
1024 }
1025
1026 pub fn noop_fold_mod<T: Folder>(Mod {inner, items}: Mod, folder: &mut T) -> Mod {
1027     Mod {
1028         inner: folder.new_span(inner),
1029         items: items.move_flat_map(|x| folder.fold_item(x)),
1030     }
1031 }
1032
1033 pub fn noop_fold_crate<T: Folder>(Crate {module, attrs, span}: Crate,
1034                                   folder: &mut T) -> Crate {
1035     let mut items = folder.fold_item(P(ast::Item {
1036         ident: keywords::Invalid.ident(),
1037         attrs,
1038         id: ast::DUMMY_NODE_ID,
1039         vis: respan(span.shrink_to_lo(), ast::VisibilityKind::Public),
1040         span,
1041         node: ast::ItemKind::Mod(module),
1042         tokens: None,
1043     })).into_iter();
1044
1045     let (module, attrs, span) = match items.next() {
1046         Some(item) => {
1047             assert!(items.next().is_none(),
1048                     "a crate cannot expand to more than one item");
1049             item.and_then(|ast::Item { attrs, span, node, .. }| {
1050                 match node {
1051                     ast::ItemKind::Mod(m) => (m, attrs, span),
1052                     _ => panic!("fold converted a module to not a module"),
1053                 }
1054             })
1055         }
1056         None => (ast::Mod {
1057             inner: span,
1058             items: vec![],
1059         }, vec![], span)
1060     };
1061
1062     Crate {
1063         module,
1064         attrs,
1065         span,
1066     }
1067 }
1068
1069 // fold one item into possibly many items
1070 pub fn noop_fold_item<T: Folder>(i: P<Item>, folder: &mut T) -> OneVector<P<Item>> {
1071     smallvec![i.map(|i| folder.fold_item_simple(i))]
1072 }
1073
1074 // fold one item into exactly one item
1075 pub fn noop_fold_item_simple<T: Folder>(Item {id, ident, attrs, node, vis, span, tokens}: Item,
1076                                         folder: &mut T) -> Item {
1077     Item {
1078         id: folder.new_id(id),
1079         vis: folder.fold_vis(vis),
1080         ident: folder.fold_ident(ident),
1081         attrs: fold_attrs(attrs, folder),
1082         node: folder.fold_item_kind(node),
1083         span: folder.new_span(span),
1084
1085         // FIXME: if this is replaced with a call to `folder.fold_tts` it causes
1086         //        an ICE during resolve... odd!
1087         tokens,
1088     }
1089 }
1090
1091 pub fn noop_fold_foreign_item<T: Folder>(ni: ForeignItem, folder: &mut T)
1092 -> OneVector<ForeignItem> {
1093     smallvec![folder.fold_foreign_item_simple(ni)]
1094 }
1095
1096 pub fn noop_fold_foreign_item_simple<T: Folder>(ni: ForeignItem, folder: &mut T) -> ForeignItem {
1097     ForeignItem {
1098         id: folder.new_id(ni.id),
1099         vis: folder.fold_vis(ni.vis),
1100         ident: folder.fold_ident(ni.ident),
1101         attrs: fold_attrs(ni.attrs, folder),
1102         node: match ni.node {
1103             ForeignItemKind::Fn(fdec, generics) => {
1104                 ForeignItemKind::Fn(folder.fold_fn_decl(fdec), folder.fold_generics(generics))
1105             }
1106             ForeignItemKind::Static(t, m) => {
1107                 ForeignItemKind::Static(folder.fold_ty(t), m)
1108             }
1109             ForeignItemKind::Ty => ForeignItemKind::Ty,
1110             ForeignItemKind::Macro(mac) => ForeignItemKind::Macro(folder.fold_mac(mac)),
1111         },
1112         span: folder.new_span(ni.span)
1113     }
1114 }
1115
1116 pub fn noop_fold_method_sig<T: Folder>(sig: MethodSig, folder: &mut T) -> MethodSig {
1117     MethodSig {
1118         header: folder.fold_fn_header(sig.header),
1119         decl: folder.fold_fn_decl(sig.decl)
1120     }
1121 }
1122
1123 pub fn noop_fold_pat<T: Folder>(p: P<Pat>, folder: &mut T) -> P<Pat> {
1124     p.map(|Pat {id, node, span}| Pat {
1125         id: folder.new_id(id),
1126         node: match node {
1127             PatKind::Wild => PatKind::Wild,
1128             PatKind::Ident(binding_mode, ident, sub) => {
1129                 PatKind::Ident(binding_mode,
1130                                folder.fold_ident(ident),
1131                                sub.map(|x| folder.fold_pat(x)))
1132             }
1133             PatKind::Lit(e) => PatKind::Lit(folder.fold_expr(e)),
1134             PatKind::TupleStruct(pth, pats, ddpos) => {
1135                 PatKind::TupleStruct(folder.fold_path(pth),
1136                         pats.move_map(|x| folder.fold_pat(x)), ddpos)
1137             }
1138             PatKind::Path(qself, pth) => {
1139                 let (qself, pth) = folder.fold_qpath(qself, pth);
1140                 PatKind::Path(qself, pth)
1141             }
1142             PatKind::Struct(pth, fields, etc) => {
1143                 let pth = folder.fold_path(pth);
1144                 let fs = fields.move_map(|f| {
1145                     Spanned { span: folder.new_span(f.span),
1146                               node: ast::FieldPat {
1147                                   ident: folder.fold_ident(f.node.ident),
1148                                   pat: folder.fold_pat(f.node.pat),
1149                                   is_shorthand: f.node.is_shorthand,
1150                                   attrs: fold_attrs(f.node.attrs.into(), folder).into()
1151                               }}
1152                 });
1153                 PatKind::Struct(pth, fs, etc)
1154             }
1155             PatKind::Tuple(elts, ddpos) => {
1156                 PatKind::Tuple(elts.move_map(|x| folder.fold_pat(x)), ddpos)
1157             }
1158             PatKind::Box(inner) => PatKind::Box(folder.fold_pat(inner)),
1159             PatKind::Ref(inner, mutbl) => PatKind::Ref(folder.fold_pat(inner), mutbl),
1160             PatKind::Range(e1, e2, Spanned { span, node: end }) => {
1161                 PatKind::Range(folder.fold_expr(e1),
1162                                folder.fold_expr(e2),
1163                                Spanned { span, node: folder.fold_range_end(end) })
1164             },
1165             PatKind::Slice(before, slice, after) => {
1166                 PatKind::Slice(before.move_map(|x| folder.fold_pat(x)),
1167                        slice.map(|x| folder.fold_pat(x)),
1168                        after.move_map(|x| folder.fold_pat(x)))
1169             }
1170             PatKind::Paren(inner) => PatKind::Paren(folder.fold_pat(inner)),
1171             PatKind::Mac(mac) => PatKind::Mac(folder.fold_mac(mac))
1172         },
1173         span: folder.new_span(span)
1174     })
1175 }
1176
1177 pub fn noop_fold_range_end<T: Folder>(end: RangeEnd, _folder: &mut T) -> RangeEnd {
1178     end
1179 }
1180
1181 pub fn noop_fold_anon_const<T: Folder>(constant: AnonConst, folder: &mut T) -> AnonConst {
1182     let AnonConst {id, value} = constant;
1183     AnonConst {
1184         id: folder.new_id(id),
1185         value: folder.fold_expr(value),
1186     }
1187 }
1188
1189 pub fn noop_fold_expr<T: Folder>(Expr {id, node, span, attrs}: Expr, folder: &mut T) -> Expr {
1190     Expr {
1191         node: match node {
1192             ExprKind::Box(e) => {
1193                 ExprKind::Box(folder.fold_expr(e))
1194             }
1195             ExprKind::ObsoleteInPlace(a, b) => {
1196                 ExprKind::ObsoleteInPlace(folder.fold_expr(a), folder.fold_expr(b))
1197             }
1198             ExprKind::Array(exprs) => {
1199                 ExprKind::Array(folder.fold_exprs(exprs))
1200             }
1201             ExprKind::Repeat(expr, count) => {
1202                 ExprKind::Repeat(folder.fold_expr(expr), folder.fold_anon_const(count))
1203             }
1204             ExprKind::Tup(exprs) => ExprKind::Tup(folder.fold_exprs(exprs)),
1205             ExprKind::Call(f, args) => {
1206                 ExprKind::Call(folder.fold_expr(f),
1207                          folder.fold_exprs(args))
1208             }
1209             ExprKind::MethodCall(seg, args) => {
1210                 ExprKind::MethodCall(
1211                     PathSegment {
1212                         ident: folder.fold_ident(seg.ident),
1213                         args: seg.args.map(|args| {
1214                             args.map(|args| folder.fold_generic_args(args))
1215                         }),
1216                     },
1217                     folder.fold_exprs(args))
1218             }
1219             ExprKind::Binary(binop, lhs, rhs) => {
1220                 ExprKind::Binary(binop,
1221                         folder.fold_expr(lhs),
1222                         folder.fold_expr(rhs))
1223             }
1224             ExprKind::Unary(binop, ohs) => {
1225                 ExprKind::Unary(binop, folder.fold_expr(ohs))
1226             }
1227             ExprKind::Lit(l) => ExprKind::Lit(l),
1228             ExprKind::Cast(expr, ty) => {
1229                 ExprKind::Cast(folder.fold_expr(expr), folder.fold_ty(ty))
1230             }
1231             ExprKind::Type(expr, ty) => {
1232                 ExprKind::Type(folder.fold_expr(expr), folder.fold_ty(ty))
1233             }
1234             ExprKind::AddrOf(m, ohs) => ExprKind::AddrOf(m, folder.fold_expr(ohs)),
1235             ExprKind::If(cond, tr, fl) => {
1236                 ExprKind::If(folder.fold_expr(cond),
1237                        folder.fold_block(tr),
1238                        fl.map(|x| folder.fold_expr(x)))
1239             }
1240             ExprKind::IfLet(pats, expr, tr, fl) => {
1241                 ExprKind::IfLet(pats.move_map(|pat| folder.fold_pat(pat)),
1242                           folder.fold_expr(expr),
1243                           folder.fold_block(tr),
1244                           fl.map(|x| folder.fold_expr(x)))
1245             }
1246             ExprKind::While(cond, body, opt_label) => {
1247                 ExprKind::While(folder.fold_expr(cond),
1248                           folder.fold_block(body),
1249                           opt_label.map(|label| folder.fold_label(label)))
1250             }
1251             ExprKind::WhileLet(pats, expr, body, opt_label) => {
1252                 ExprKind::WhileLet(pats.move_map(|pat| folder.fold_pat(pat)),
1253                              folder.fold_expr(expr),
1254                              folder.fold_block(body),
1255                              opt_label.map(|label| folder.fold_label(label)))
1256             }
1257             ExprKind::ForLoop(pat, iter, body, opt_label) => {
1258                 ExprKind::ForLoop(folder.fold_pat(pat),
1259                             folder.fold_expr(iter),
1260                             folder.fold_block(body),
1261                             opt_label.map(|label| folder.fold_label(label)))
1262             }
1263             ExprKind::Loop(body, opt_label) => {
1264                 ExprKind::Loop(folder.fold_block(body),
1265                                opt_label.map(|label| folder.fold_label(label)))
1266             }
1267             ExprKind::Match(expr, arms) => {
1268                 ExprKind::Match(folder.fold_expr(expr),
1269                           arms.move_map(|x| folder.fold_arm(x)))
1270             }
1271             ExprKind::Closure(capture_clause, asyncness, movability, decl, body, span) => {
1272                 ExprKind::Closure(capture_clause,
1273                                   folder.fold_asyncness(asyncness),
1274                                   movability,
1275                                   folder.fold_fn_decl(decl),
1276                                   folder.fold_expr(body),
1277                                   folder.new_span(span))
1278             }
1279             ExprKind::Block(blk, opt_label) => {
1280                 ExprKind::Block(folder.fold_block(blk),
1281                                 opt_label.map(|label| folder.fold_label(label)))
1282             }
1283             ExprKind::Async(capture_clause, node_id, body) => {
1284                 ExprKind::Async(
1285                     capture_clause,
1286                     folder.new_id(node_id),
1287                     folder.fold_block(body),
1288                 )
1289             }
1290             ExprKind::Assign(el, er) => {
1291                 ExprKind::Assign(folder.fold_expr(el), folder.fold_expr(er))
1292             }
1293             ExprKind::AssignOp(op, el, er) => {
1294                 ExprKind::AssignOp(op,
1295                             folder.fold_expr(el),
1296                             folder.fold_expr(er))
1297             }
1298             ExprKind::Field(el, ident) => {
1299                 ExprKind::Field(folder.fold_expr(el), folder.fold_ident(ident))
1300             }
1301             ExprKind::Index(el, er) => {
1302                 ExprKind::Index(folder.fold_expr(el), folder.fold_expr(er))
1303             }
1304             ExprKind::Range(e1, e2, lim) => {
1305                 ExprKind::Range(e1.map(|x| folder.fold_expr(x)),
1306                                 e2.map(|x| folder.fold_expr(x)),
1307                                 lim)
1308             }
1309             ExprKind::Path(qself, path) => {
1310                 let (qself, path) = folder.fold_qpath(qself, path);
1311                 ExprKind::Path(qself, path)
1312             }
1313             ExprKind::Break(opt_label, opt_expr) => {
1314                 ExprKind::Break(opt_label.map(|label| folder.fold_label(label)),
1315                                 opt_expr.map(|e| folder.fold_expr(e)))
1316             }
1317             ExprKind::Continue(opt_label) => {
1318                 ExprKind::Continue(opt_label.map(|label| folder.fold_label(label)))
1319             }
1320             ExprKind::Ret(e) => ExprKind::Ret(e.map(|x| folder.fold_expr(x))),
1321             ExprKind::InlineAsm(asm) => ExprKind::InlineAsm(asm.map(|asm| {
1322                 InlineAsm {
1323                     inputs: asm.inputs.move_map(|(c, input)| {
1324                         (c, folder.fold_expr(input))
1325                     }),
1326                     outputs: asm.outputs.move_map(|out| {
1327                         InlineAsmOutput {
1328                             constraint: out.constraint,
1329                             expr: folder.fold_expr(out.expr),
1330                             is_rw: out.is_rw,
1331                             is_indirect: out.is_indirect,
1332                         }
1333                     }),
1334                     ..asm
1335                 }
1336             })),
1337             ExprKind::Mac(mac) => ExprKind::Mac(folder.fold_mac(mac)),
1338             ExprKind::Struct(path, fields, maybe_expr) => {
1339                 ExprKind::Struct(folder.fold_path(path),
1340                         fields.move_map(|x| folder.fold_field(x)),
1341                         maybe_expr.map(|x| folder.fold_expr(x)))
1342             },
1343             ExprKind::Paren(ex) => {
1344                 let sub_expr = folder.fold_expr(ex);
1345                 return Expr {
1346                     // Nodes that are equal modulo `Paren` sugar no-ops should have the same ids.
1347                     id: sub_expr.id,
1348                     node: ExprKind::Paren(sub_expr),
1349                     span: folder.new_span(span),
1350                     attrs: fold_attrs(attrs.into(), folder).into(),
1351                 };
1352             }
1353             ExprKind::Yield(ex) => ExprKind::Yield(ex.map(|x| folder.fold_expr(x))),
1354             ExprKind::Try(ex) => ExprKind::Try(folder.fold_expr(ex)),
1355             ExprKind::TryBlock(body) => ExprKind::TryBlock(folder.fold_block(body)),
1356         },
1357         id: folder.new_id(id),
1358         span: folder.new_span(span),
1359         attrs: fold_attrs(attrs.into(), folder).into(),
1360     }
1361 }
1362
1363 pub fn noop_fold_opt_expr<T: Folder>(e: P<Expr>, folder: &mut T) -> Option<P<Expr>> {
1364     Some(folder.fold_expr(e))
1365 }
1366
1367 pub fn noop_fold_exprs<T: Folder>(es: Vec<P<Expr>>, folder: &mut T) -> Vec<P<Expr>> {
1368     es.move_flat_map(|e| folder.fold_opt_expr(e))
1369 }
1370
1371 pub fn noop_fold_stmt<T: Folder>(Stmt {node, span, id}: Stmt, folder: &mut T) -> OneVector<Stmt> {
1372     let id = folder.new_id(id);
1373     let span = folder.new_span(span);
1374     noop_fold_stmt_kind(node, folder).into_iter().map(|node| {
1375         Stmt { id: id, node: node, span: span }
1376     }).collect()
1377 }
1378
1379 pub fn noop_fold_stmt_kind<T: Folder>(node: StmtKind, folder: &mut T) -> OneVector<StmtKind> {
1380     match node {
1381         StmtKind::Local(local) => smallvec![StmtKind::Local(folder.fold_local(local))],
1382         StmtKind::Item(item) => folder.fold_item(item).into_iter().map(StmtKind::Item).collect(),
1383         StmtKind::Expr(expr) => {
1384             folder.fold_opt_expr(expr).into_iter().map(StmtKind::Expr).collect()
1385         }
1386         StmtKind::Semi(expr) => {
1387             folder.fold_opt_expr(expr).into_iter().map(StmtKind::Semi).collect()
1388         }
1389         StmtKind::Mac(mac) => smallvec![StmtKind::Mac(mac.map(|(mac, semi, attrs)| {
1390             (folder.fold_mac(mac), semi, fold_attrs(attrs.into(), folder).into())
1391         }))],
1392     }
1393 }
1394
1395 pub fn noop_fold_vis<T: Folder>(vis: Visibility, folder: &mut T) -> Visibility {
1396     match vis.node {
1397         VisibilityKind::Restricted { path, id } => {
1398             respan(vis.span, VisibilityKind::Restricted {
1399                 path: path.map(|path| folder.fold_path(path)),
1400                 id: folder.new_id(id),
1401             })
1402         }
1403         _ => vis,
1404     }
1405 }
1406
1407 #[cfg(test)]
1408 mod tests {
1409     use std::io;
1410     use ast::{self, Ident};
1411     use util::parser_testing::{string_to_crate, matches_codepattern};
1412     use print::pprust;
1413     use fold;
1414     use with_globals;
1415     use super::*;
1416
1417     // this version doesn't care about getting comments or docstrings in.
1418     fn fake_print_crate(s: &mut pprust::State,
1419                         krate: &ast::Crate) -> io::Result<()> {
1420         s.print_mod(&krate.module, &krate.attrs)
1421     }
1422
1423     // change every identifier to "zz"
1424     struct ToZzIdentFolder;
1425
1426     impl Folder for ToZzIdentFolder {
1427         fn fold_ident(&mut self, _: ast::Ident) -> ast::Ident {
1428             Ident::from_str("zz")
1429         }
1430         fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
1431             fold::noop_fold_mac(mac, self)
1432         }
1433     }
1434
1435     // maybe add to expand.rs...
1436     macro_rules! assert_pred {
1437         ($pred:expr, $predname:expr, $a:expr , $b:expr) => (
1438             {
1439                 let pred_val = $pred;
1440                 let a_val = $a;
1441                 let b_val = $b;
1442                 if !(pred_val(&a_val, &b_val)) {
1443                     panic!("expected args satisfying {}, got {} and {}",
1444                           $predname, a_val, b_val);
1445                 }
1446             }
1447         )
1448     }
1449
1450     // make sure idents get transformed everywhere
1451     #[test] fn ident_transformation () {
1452         with_globals(|| {
1453             let mut zz_fold = ToZzIdentFolder;
1454             let ast = string_to_crate(
1455                 "#[a] mod b {fn c (d : e, f : g) {h!(i,j,k);l;m}}".to_string());
1456             let folded_crate = zz_fold.fold_crate(ast);
1457             assert_pred!(
1458                 matches_codepattern,
1459                 "matches_codepattern",
1460                 pprust::to_string(|s| fake_print_crate(s, &folded_crate)),
1461                 "#[zz]mod zz{fn zz(zz:zz,zz:zz){zz!(zz,zz,zz);zz;zz}}".to_string());
1462         })
1463     }
1464
1465     // even inside macro defs....
1466     #[test] fn ident_transformation_in_defs () {
1467         with_globals(|| {
1468             let mut zz_fold = ToZzIdentFolder;
1469             let ast = string_to_crate(
1470                 "macro_rules! a {(b $c:expr $(d $e:token)f+ => \
1471                 (g $(d $d $e)+))} ".to_string());
1472             let folded_crate = zz_fold.fold_crate(ast);
1473             assert_pred!(
1474                 matches_codepattern,
1475                 "matches_codepattern",
1476                 pprust::to_string(|s| fake_print_crate(s, &folded_crate)),
1477                 "macro_rules! zz((zz$zz:zz$(zz $zz:zz)zz+=>(zz$(zz$zz$zz)+)));".to_string());
1478         })
1479     }
1480 }