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 codemap::{Spanned, respan};
  25 use parse::token;
  26 use ptr::P;
  27 use symbol::keywords;
  28 use tokenstream::*;
  29 use util::small_vector::SmallVector;
  30 use util::move_map::MoveMap;
  31
  32 use std::rc::Rc;
  33
  34 pub trait Folder : Sized {
  35     // Any additions to this trait should happen in form
  36     // of a call to a public `noop_*` function that only calls
  37     // out to the folder again, not other `noop_*` functions.
  38     //
  39     // This is a necessary API workaround to the problem of not
  40     // being able to call out to the super default method
  41     // in an overridden default method.
  42
  43     fn fold_crate(&mut self, c: Crate) -> Crate {
  44         noop_fold_crate(c, self)
  45     }
  46
  47     fn fold_meta_items(&mut self, meta_items: Vec<MetaItem>) -> Vec<MetaItem> {
  48         noop_fold_meta_items(meta_items, self)
  49     }
  50
  51     fn fold_meta_list_item(&mut self, list_item: NestedMetaItem) -> NestedMetaItem {
  52         noop_fold_meta_list_item(list_item, self)
  53     }
  54
  55     fn fold_meta_item(&mut self, meta_item: MetaItem) -> MetaItem {
  56         noop_fold_meta_item(meta_item, self)
  57     }
  58
  59     fn fold_view_path(&mut self, view_path: P<ViewPath>) -> P<ViewPath> {
  60         noop_fold_view_path(view_path, self)
  61     }
  62
  63     fn fold_foreign_item(&mut self, ni: ForeignItem) -> ForeignItem {
  64         noop_fold_foreign_item(ni, self)
  65     }
  66
  67     fn fold_item(&mut self, i: P<Item>) -> SmallVector<P<Item>> {
  68         noop_fold_item(i, self)
  69     }
  70
  71     fn fold_item_simple(&mut self, i: Item) -> Item {
  72         noop_fold_item_simple(i, self)
  73     }
  74
  75     fn fold_struct_field(&mut self, sf: StructField) -> StructField {
  76         noop_fold_struct_field(sf, self)
  77     }
  78
  79     fn fold_item_kind(&mut self, i: ItemKind) -> ItemKind {
  80         noop_fold_item_kind(i, self)
  81     }
  82
  83     fn fold_trait_item(&mut self, i: TraitItem) -> SmallVector<TraitItem> {
  84         noop_fold_trait_item(i, self)
  85     }
  86
  87     fn fold_impl_item(&mut self, i: ImplItem) -> SmallVector<ImplItem> {
  88         noop_fold_impl_item(i, self)
  89     }
  90
  91     fn fold_fn_decl(&mut self, d: P<FnDecl>) -> P<FnDecl> {
  92         noop_fold_fn_decl(d, self)
  93     }
  94
  95     fn fold_block(&mut self, b: P<Block>) -> P<Block> {
  96         noop_fold_block(b, self)
  97     }
  98
  99     fn fold_stmt(&mut self, s: Stmt) -> SmallVector<Stmt> {
 100         noop_fold_stmt(s, self)
 101     }
 102
 103     fn fold_arm(&mut self, a: Arm) -> Arm {
 104         noop_fold_arm(a, self)
 105     }
 106
 107     fn fold_pat(&mut self, p: P<Pat>) -> P<Pat> {
 108         noop_fold_pat(p, self)
 109     }
 110
 111     fn fold_expr(&mut self, e: P<Expr>) -> P<Expr> {
 112         e.map(|e| noop_fold_expr(e, self))
 113     }
 114
 115     fn fold_range_end(&mut self, re: RangeEnd) -> RangeEnd {
 116         noop_fold_range_end(re, self)
 117     }
 118
 119     fn fold_opt_expr(&mut self, e: P<Expr>) -> Option<P<Expr>> {
 120         noop_fold_opt_expr(e, self)
 121     }
 122
 123     fn fold_exprs(&mut self, es: Vec<P<Expr>>) -> Vec<P<Expr>> {
 124         noop_fold_exprs(es, self)
 125     }
 126
 127     fn fold_ty(&mut self, t: P<Ty>) -> P<Ty> {
 128         noop_fold_ty(t, self)
 129     }
 130
 131     fn fold_ty_binding(&mut self, t: TypeBinding) -> TypeBinding {
 132         noop_fold_ty_binding(t, self)
 133     }
 134
 135     fn fold_mod(&mut self, m: Mod) -> Mod {
 136         noop_fold_mod(m, self)
 137     }
 138
 139     fn fold_foreign_mod(&mut self, nm: ForeignMod) -> ForeignMod {
 140         noop_fold_foreign_mod(nm, self)
 141     }
 142
 143     fn fold_global_asm(&mut self, ga: P<GlobalAsm>) -> P<GlobalAsm> {
 144         noop_fold_global_asm(ga, self)
 145     }
 146
 147     fn fold_variant(&mut self, v: Variant) -> Variant {
 148         noop_fold_variant(v, self)
 149     }
 150
 151     fn fold_ident(&mut self, i: Ident) -> Ident {
 152         noop_fold_ident(i, self)
 153     }
 154
 155     fn fold_usize(&mut self, i: usize) -> usize {
 156         noop_fold_usize(i, self)
 157     }
 158
 159     fn fold_path(&mut self, p: Path) -> Path {
 160         noop_fold_path(p, self)
 161     }
 162
 163     fn fold_path_parameters(&mut self, p: PathParameters) -> PathParameters {
 164         noop_fold_path_parameters(p, self)
 165     }
 166
 167     fn fold_angle_bracketed_parameter_data(&mut self, p: AngleBracketedParameterData)
 168                                            -> AngleBracketedParameterData
 169     {
 170         noop_fold_angle_bracketed_parameter_data(p, self)
 171     }
 172
 173     fn fold_parenthesized_parameter_data(&mut self, p: ParenthesizedParameterData)
 174                                          -> ParenthesizedParameterData
 175     {
 176         noop_fold_parenthesized_parameter_data(p, self)
 177     }
 178
 179     fn fold_local(&mut self, l: P<Local>) -> P<Local> {
 180         noop_fold_local(l, self)
 181     }
 182
 183     fn fold_mac(&mut self, _mac: Mac) -> Mac {
 184         panic!("fold_mac disabled by default");
 185         // NB: see note about macros above.
 186         // if you really want a folder that
 187         // works on macros, use this
 188         // definition in your trait impl:
 189         // fold::noop_fold_mac(_mac, self)
 190     }
 191
 192     fn fold_lifetime(&mut self, l: Lifetime) -> Lifetime {
 193         noop_fold_lifetime(l, self)
 194     }
 195
 196     fn fold_lifetime_def(&mut self, l: LifetimeDef) -> LifetimeDef {
 197         noop_fold_lifetime_def(l, self)
 198     }
 199
 200     fn fold_attribute(&mut self, at: Attribute) -> Option<Attribute> {
 201         noop_fold_attribute(at, self)
 202     }
 203
 204     fn fold_arg(&mut self, a: Arg) -> Arg {
 205         noop_fold_arg(a, self)
 206     }
 207
 208     fn fold_generics(&mut self, generics: Generics) -> Generics {
 209         noop_fold_generics(generics, self)
 210     }
 211
 212     fn fold_trait_ref(&mut self, p: TraitRef) -> TraitRef {
 213         noop_fold_trait_ref(p, self)
 214     }
 215
 216     fn fold_poly_trait_ref(&mut self, p: PolyTraitRef) -> PolyTraitRef {
 217         noop_fold_poly_trait_ref(p, self)
 218     }
 219
 220     fn fold_variant_data(&mut self, vdata: VariantData) -> VariantData {
 221         noop_fold_variant_data(vdata, self)
 222     }
 223
 224     fn fold_lifetimes(&mut self, lts: Vec<Lifetime>) -> Vec<Lifetime> {
 225         noop_fold_lifetimes(lts, self)
 226     }
 227
 228     fn fold_lifetime_defs(&mut self, lts: Vec<LifetimeDef>) -> Vec<LifetimeDef> {
 229         noop_fold_lifetime_defs(lts, self)
 230     }
 231
 232     fn fold_ty_param(&mut self, tp: TyParam) -> TyParam {
 233         noop_fold_ty_param(tp, self)
 234     }
 235
 236     fn fold_ty_params(&mut self, tps: Vec<TyParam>) -> Vec<TyParam> {
 237         noop_fold_ty_params(tps, self)
 238     }
 239
 240     fn fold_tt(&mut self, tt: TokenTree) -> TokenTree {
 241         noop_fold_tt(tt, self)
 242     }
 243
 244     fn fold_tts(&mut self, tts: TokenStream) -> TokenStream {
 245         noop_fold_tts(tts, self)
 246     }
 247
 248     fn fold_token(&mut self, t: token::Token) -> token::Token {
 249         noop_fold_token(t, self)
 250     }
 251
 252     fn fold_interpolated(&mut self, nt: token::Nonterminal) -> token::Nonterminal {
 253         noop_fold_interpolated(nt, self)
 254     }
 255
 256     fn fold_opt_lifetime(&mut self, o_lt: Option<Lifetime>) -> Option<Lifetime> {
 257         noop_fold_opt_lifetime(o_lt, self)
 258     }
 259
 260     fn fold_opt_bounds(&mut self, b: Option<TyParamBounds>)
 261                        -> Option<TyParamBounds> {
 262         noop_fold_opt_bounds(b, self)
 263     }
 264
 265     fn fold_bounds(&mut self, b: TyParamBounds)
 266                        -> TyParamBounds {
 267         noop_fold_bounds(b, self)
 268     }
 269
 270     fn fold_ty_param_bound(&mut self, tpb: TyParamBound) -> TyParamBound {
 271         noop_fold_ty_param_bound(tpb, self)
 272     }
 273
 274     fn fold_mt(&mut self, mt: MutTy) -> MutTy {
 275         noop_fold_mt(mt, self)
 276     }
 277
 278     fn fold_field(&mut self, field: Field) -> Field {
 279         noop_fold_field(field, self)
 280     }
 281
 282     fn fold_where_clause(&mut self, where_clause: WhereClause)
 283                          -> WhereClause {
 284         noop_fold_where_clause(where_clause, self)
 285     }
 286
 287     fn fold_where_predicate(&mut self, where_predicate: WherePredicate)
 288                             -> WherePredicate {
 289         noop_fold_where_predicate(where_predicate, self)
 290     }
 291
 292     fn fold_vis(&mut self, vis: Visibility) -> Visibility {
 293         noop_fold_vis(vis, self)
 294     }
 295
 296     fn new_id(&mut self, i: NodeId) -> NodeId {
 297         i
 298     }
 299
 300     fn new_span(&mut self, sp: Span) -> Span {
 301         sp
 302     }
 303 }
 304
 305 pub fn noop_fold_meta_items<T: Folder>(meta_items: Vec<MetaItem>, fld: &mut T) -> Vec<MetaItem> {
 306     meta_items.move_map(|x| fld.fold_meta_item(x))
 307 }
 308
 309 pub fn noop_fold_view_path<T: Folder>(view_path: P<ViewPath>, fld: &mut T) -> P<ViewPath> {
 310     view_path.map(|Spanned {node, span}| Spanned {
 311         node: match node {
 312             ViewPathSimple(ident, path) => {
 313                 ViewPathSimple(fld.fold_ident(ident), fld.fold_path(path))
 314             }
 315             ViewPathGlob(path) => {
 316                 ViewPathGlob(fld.fold_path(path))
 317             }
 318             ViewPathList(path, path_list_idents) => {
 319                 let path = fld.fold_path(path);
 320                 let path_list_idents = path_list_idents.move_map(|path_list_ident| Spanned {
 321                     node: PathListItem_ {
 322                         id: fld.new_id(path_list_ident.node.id),
 323                         rename: path_list_ident.node.rename.map(|ident| fld.fold_ident(ident)),
 324                         name: fld.fold_ident(path_list_ident.node.name),
 325                     },
 326                     span: fld.new_span(path_list_ident.span)
 327                 });
 328                 ViewPathList(path, path_list_idents)
 329             }
 330         },
 331         span: fld.new_span(span)
 332     })
 333 }
 334
 335 pub fn fold_attrs<T: Folder>(attrs: Vec<Attribute>, fld: &mut T) -> Vec<Attribute> {
 336     attrs.move_flat_map(|x| fld.fold_attribute(x))
 337 }
 338
 339 pub fn fold_thin_attrs<T: Folder>(attrs: ThinVec<Attribute>, fld: &mut T) -> ThinVec<Attribute> {
 340     fold_attrs(attrs.into(), fld).into()
 341 }
 342
 343 pub fn noop_fold_arm<T: Folder>(Arm {attrs, pats, guard, body}: Arm, fld: &mut T) -> Arm {
 344     Arm {
 345         attrs: fold_attrs(attrs, fld),
 346         pats: pats.move_map(|x| fld.fold_pat(x)),
 347         guard: guard.map(|x| fld.fold_expr(x)),
 348         body: fld.fold_expr(body),
 349     }
 350 }
 351
 352 pub fn noop_fold_ty_binding<T: Folder>(b: TypeBinding, fld: &mut T) -> TypeBinding {
 353     TypeBinding {
 354         id: fld.new_id(b.id),
 355         ident: fld.fold_ident(b.ident),
 356         ty: fld.fold_ty(b.ty),
 357         span: fld.new_span(b.span),
 358     }
 359 }
 360
 361 pub fn noop_fold_ty<T: Folder>(t: P<Ty>, fld: &mut T) -> P<Ty> {
 362     t.map(|Ty {id, node, span}| Ty {
 363         id: fld.new_id(id),
 364         node: match node {
 365             TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err => node,
 366             TyKind::Slice(ty) => TyKind::Slice(fld.fold_ty(ty)),
 367             TyKind::Ptr(mt) => TyKind::Ptr(fld.fold_mt(mt)),
 368             TyKind::Rptr(region, mt) => {
 369                 TyKind::Rptr(fld.fold_opt_lifetime(region), fld.fold_mt(mt))
 370             }
 371             TyKind::BareFn(f) => {
 372                 TyKind::BareFn(f.map(|BareFnTy {lifetimes, unsafety, abi, decl}| BareFnTy {
 373                     lifetimes: fld.fold_lifetime_defs(lifetimes),
 374                     unsafety: unsafety,
 375                     abi: abi,
 376                     decl: fld.fold_fn_decl(decl)
 377                 }))
 378             }
 379             TyKind::Never => node,
 380             TyKind::Tup(tys) => TyKind::Tup(tys.move_map(|ty| fld.fold_ty(ty))),
 381             TyKind::Paren(ty) => TyKind::Paren(fld.fold_ty(ty)),
 382             TyKind::Path(qself, path) => {
 383                 let qself = qself.map(|QSelf { ty, position }| {
 384                     QSelf {
 385                         ty: fld.fold_ty(ty),
 386                         position: position
 387                     }
 388                 });
 389                 TyKind::Path(qself, fld.fold_path(path))
 390             }
 391             TyKind::Array(ty, e) => {
 392                 TyKind::Array(fld.fold_ty(ty), fld.fold_expr(e))
 393             }
 394             TyKind::Typeof(expr) => {
 395                 TyKind::Typeof(fld.fold_expr(expr))
 396             }
 397             TyKind::TraitObject(bounds) => {
 398                 TyKind::TraitObject(bounds.move_map(|b| fld.fold_ty_param_bound(b)))
 399             }
 400             TyKind::ImplTrait(bounds) => {
 401                 TyKind::ImplTrait(bounds.move_map(|b| fld.fold_ty_param_bound(b)))
 402             }
 403             TyKind::Mac(mac) => {
 404                 TyKind::Mac(fld.fold_mac(mac))
 405             }
 406         },
 407         span: fld.new_span(span)
 408     })
 409 }
 410
 411 pub fn noop_fold_foreign_mod<T: Folder>(ForeignMod {abi, items}: ForeignMod,
 412                                         fld: &mut T) -> ForeignMod {
 413     ForeignMod {
 414         abi: abi,
 415         items: items.move_map(|x| fld.fold_foreign_item(x)),
 416     }
 417 }
 418
 419 pub fn noop_fold_global_asm<T: Folder>(ga: P<GlobalAsm>,
 420                                        _: &mut T) -> P<GlobalAsm> {
 421     ga
 422 }
 423
 424 pub fn noop_fold_variant<T: Folder>(v: Variant, fld: &mut T) -> Variant {
 425     Spanned {
 426         node: Variant_ {
 427             name: v.node.name,
 428             attrs: fold_attrs(v.node.attrs, fld),
 429             data: fld.fold_variant_data(v.node.data),
 430             disr_expr: v.node.disr_expr.map(|e| fld.fold_expr(e)),
 431         },
 432         span: fld.new_span(v.span),
 433     }
 434 }
 435
 436 pub fn noop_fold_ident<T: Folder>(i: Ident, _: &mut T) -> Ident {
 437     i
 438 }
 439
 440 pub fn noop_fold_usize<T: Folder>(i: usize, _: &mut T) -> usize {
 441     i
 442 }
 443
 444 pub fn noop_fold_path<T: Folder>(Path { segments, span }: Path, fld: &mut T) -> Path {
 445     Path {
 446         segments: segments.move_map(|PathSegment {identifier, span, parameters}| PathSegment {
 447             identifier: fld.fold_ident(identifier),
 448             span: fld.new_span(span),
 449             parameters: parameters.map(|ps| ps.map(|ps| fld.fold_path_parameters(ps))),
 450         }),
 451         span: fld.new_span(span)
 452     }
 453 }
 454
 455 pub fn noop_fold_path_parameters<T: Folder>(path_parameters: PathParameters, fld: &mut T)
 456                                             -> PathParameters
 457 {
 458     match path_parameters {
 459         PathParameters::AngleBracketed(data) =>
 460             PathParameters::AngleBracketed(fld.fold_angle_bracketed_parameter_data(data)),
 461         PathParameters::Parenthesized(data) =>
 462             PathParameters::Parenthesized(fld.fold_parenthesized_parameter_data(data)),
 463     }
 464 }
 465
 466 pub fn noop_fold_angle_bracketed_parameter_data<T: Folder>(data: AngleBracketedParameterData,
 467                                                            fld: &mut T)
 468                                                            -> AngleBracketedParameterData
 469 {
 470     let AngleBracketedParameterData { lifetimes, types, bindings } = data;
 471     AngleBracketedParameterData { lifetimes: fld.fold_lifetimes(lifetimes),
 472                                   types: types.move_map(|ty| fld.fold_ty(ty)),
 473                                   bindings: bindings.move_map(|b| fld.fold_ty_binding(b)) }
 474 }
 475
 476 pub fn noop_fold_parenthesized_parameter_data<T: Folder>(data: ParenthesizedParameterData,
 477                                                          fld: &mut T)
 478                                                          -> ParenthesizedParameterData
 479 {
 480     let ParenthesizedParameterData { inputs, output, span } = data;
 481     ParenthesizedParameterData { inputs: inputs.move_map(|ty| fld.fold_ty(ty)),
 482                                  output: output.map(|ty| fld.fold_ty(ty)),
 483                                  span: fld.new_span(span) }
 484 }
 485
 486 pub fn noop_fold_local<T: Folder>(l: P<Local>, fld: &mut T) -> P<Local> {
 487     l.map(|Local {id, pat, ty, init, span, attrs}| Local {
 488         id: fld.new_id(id),
 489         pat: fld.fold_pat(pat),
 490         ty: ty.map(|t| fld.fold_ty(t)),
 491         init: init.map(|e| fld.fold_expr(e)),
 492         span: fld.new_span(span),
 493         attrs: fold_attrs(attrs.into(), fld).into(),
 494     })
 495 }
 496
 497 pub fn noop_fold_attribute<T: Folder>(attr: Attribute, fld: &mut T) -> Option<Attribute> {
 498     Some(Attribute {
 499         id: attr.id,
 500         style: attr.style,
 501         path: fld.fold_path(attr.path),
 502         tokens: fld.fold_tts(attr.tokens),
 503         is_sugared_doc: attr.is_sugared_doc,
 504         span: fld.new_span(attr.span),
 505     })
 506 }
 507
 508 pub fn noop_fold_mac<T: Folder>(Spanned {node, span}: Mac, fld: &mut T) -> Mac {
 509     Spanned {
 510         node: Mac_ {
 511             tts: fld.fold_tts(node.stream()).into(),
 512             path: fld.fold_path(node.path),
 513         },
 514         span: fld.new_span(span)
 515     }
 516 }
 517
 518 pub fn noop_fold_meta_list_item<T: Folder>(li: NestedMetaItem, fld: &mut T)
 519     -> NestedMetaItem {
 520     Spanned {
 521         node: match li.node {
 522             NestedMetaItemKind::MetaItem(mi) =>  {
 523                 NestedMetaItemKind::MetaItem(fld.fold_meta_item(mi))
 524             },
 525             NestedMetaItemKind::Literal(lit) => NestedMetaItemKind::Literal(lit)
 526         },
 527         span: fld.new_span(li.span)
 528     }
 529 }
 530
 531 pub fn noop_fold_meta_item<T: Folder>(mi: MetaItem, fld: &mut T) -> MetaItem {
 532     MetaItem {
 533         name: mi.name,
 534         node: match mi.node {
 535             MetaItemKind::Word => MetaItemKind::Word,
 536             MetaItemKind::List(mis) => {
 537                 MetaItemKind::List(mis.move_map(|e| fld.fold_meta_list_item(e)))
 538             },
 539             MetaItemKind::NameValue(s) => MetaItemKind::NameValue(s),
 540         },
 541         span: fld.new_span(mi.span)
 542     }
 543 }
 544
 545 pub fn noop_fold_arg<T: Folder>(Arg {id, pat, ty}: Arg, fld: &mut T) -> Arg {
 546     Arg {
 547         id: fld.new_id(id),
 548         pat: fld.fold_pat(pat),
 549         ty: fld.fold_ty(ty)
 550     }
 551 }
 552
 553 pub fn noop_fold_tt<T: Folder>(tt: TokenTree, fld: &mut T) -> TokenTree {
 554     match tt {
 555         TokenTree::Token(span, tok) =>
 556             TokenTree::Token(fld.new_span(span), fld.fold_token(tok)),
 557         TokenTree::Delimited(span, delimed) => TokenTree::Delimited(fld.new_span(span), Delimited {
 558             tts: fld.fold_tts(delimed.stream()).into(),
 559             delim: delimed.delim,
 560         }),
 561     }
 562 }
 563
 564 pub fn noop_fold_tts<T: Folder>(tts: TokenStream, fld: &mut T) -> TokenStream {
 565     tts.trees().map(|tt| fld.fold_tt(tt)).collect()
 566 }
 567
 568 // apply ident folder if it's an ident, apply other folds to interpolated nodes
 569 pub fn noop_fold_token<T: Folder>(t: token::Token, fld: &mut T) -> token::Token {
 570     match t {
 571         token::Ident(id) => token::Ident(fld.fold_ident(id)),
 572         token::Lifetime(id) => token::Lifetime(fld.fold_ident(id)),
 573         token::Interpolated(nt) => {
 574             let nt = match Rc::try_unwrap(nt) {
 575                 Ok(nt) => nt,
 576                 Err(nt) => (*nt).clone(),
 577             };
 578             token::Interpolated(Rc::new(fld.fold_interpolated(nt)))
 579         }
 580         token::SubstNt(ident) => token::SubstNt(fld.fold_ident(ident)),
 581         _ => t
 582     }
 583 }
 584
 585 /// apply folder to elements of interpolated nodes
 586 //
 587 // NB: this can occur only when applying a fold to partially expanded code, where
 588 // parsed pieces have gotten implanted ito *other* macro invocations. This is relevant
 589 // for macro hygiene, but possibly not elsewhere.
 590 //
 591 // One problem here occurs because the types for fold_item, fold_stmt, etc. allow the
 592 // folder to return *multiple* items; this is a problem for the nodes here, because
 593 // they insist on having exactly one piece. One solution would be to mangle the fold
 594 // trait to include one-to-many and one-to-one versions of these entry points, but that
 595 // would probably confuse a lot of people and help very few. Instead, I'm just going
 596 // to put in dynamic checks. I think the performance impact of this will be pretty much
 597 // nonexistent. The danger is that someone will apply a fold to a partially expanded
 598 // node, and will be confused by the fact that their "fold_item" or "fold_stmt" isn't
 599 // getting called on NtItem or NtStmt nodes. Hopefully they'll wind up reading this
 600 // comment, and doing something appropriate.
 601 //
 602 // BTW, design choice: I considered just changing the type of, e.g., NtItem to contain
 603 // multiple items, but decided against it when I looked at parse_item_or_view_item and
 604 // tried to figure out what I would do with multiple items there....
 605 pub fn noop_fold_interpolated<T: Folder>(nt: token::Nonterminal, fld: &mut T)
 606                                          -> token::Nonterminal {
 607     match nt {
 608         token::NtItem(item) =>
 609             token::NtItem(fld.fold_item(item)
 610                           // this is probably okay, because the only folds likely
 611                           // to peek inside interpolated nodes will be renamings/markings,
 612                           // which map single items to single items
 613                           .expect_one("expected fold to produce exactly one item")),
 614         token::NtBlock(block) => token::NtBlock(fld.fold_block(block)),
 615         token::NtStmt(stmt) =>
 616             token::NtStmt(fld.fold_stmt(stmt)
 617                           // this is probably okay, because the only folds likely
 618                           // to peek inside interpolated nodes will be renamings/markings,
 619                           // which map single items to single items
 620                           .expect_one("expected fold to produce exactly one statement")),
 621         token::NtPat(pat) => token::NtPat(fld.fold_pat(pat)),
 622         token::NtExpr(expr) => token::NtExpr(fld.fold_expr(expr)),
 623         token::NtTy(ty) => token::NtTy(fld.fold_ty(ty)),
 624         token::NtIdent(id) => token::NtIdent(Spanned::<Ident>{node: fld.fold_ident(id.node), ..id}),
 625         token::NtMeta(meta) => token::NtMeta(fld.fold_meta_item(meta)),
 626         token::NtPath(path) => token::NtPath(fld.fold_path(path)),
 627         token::NtTT(tt) => token::NtTT(fld.fold_tt(tt)),
 628         token::NtArm(arm) => token::NtArm(fld.fold_arm(arm)),
 629         token::NtImplItem(item) =>
 630             token::NtImplItem(fld.fold_impl_item(item)
 631                               .expect_one("expected fold to produce exactly one item")),
 632         token::NtTraitItem(item) =>
 633             token::NtTraitItem(fld.fold_trait_item(item)
 634                                .expect_one("expected fold to produce exactly one item")),
 635         token::NtGenerics(generics) => token::NtGenerics(fld.fold_generics(generics)),
 636         token::NtWhereClause(where_clause) =>
 637             token::NtWhereClause(fld.fold_where_clause(where_clause)),
 638         token::NtArg(arg) => token::NtArg(fld.fold_arg(arg)),
 639     }
 640 }
 641
 642 pub fn noop_fold_fn_decl<T: Folder>(decl: P<FnDecl>, fld: &mut T) -> P<FnDecl> {
 643     decl.map(|FnDecl {inputs, output, variadic}| FnDecl {
 644         inputs: inputs.move_map(|x| fld.fold_arg(x)),
 645         output: match output {
 646             FunctionRetTy::Ty(ty) => FunctionRetTy::Ty(fld.fold_ty(ty)),
 647             FunctionRetTy::Default(span) => FunctionRetTy::Default(fld.new_span(span)),
 648         },
 649         variadic: variadic
 650     })
 651 }
 652
 653 pub fn noop_fold_ty_param_bound<T>(tpb: TyParamBound, fld: &mut T)
 654                                    -> TyParamBound
 655                                    where T: Folder {
 656     match tpb {
 657         TraitTyParamBound(ty, modifier) => TraitTyParamBound(fld.fold_poly_trait_ref(ty), modifier),
 658         RegionTyParamBound(lifetime) => RegionTyParamBound(fld.fold_lifetime(lifetime)),
 659     }
 660 }
 661
 662 pub fn noop_fold_ty_param<T: Folder>(tp: TyParam, fld: &mut T) -> TyParam {
 663     let TyParam {attrs, id, ident, bounds, default, span} = tp;
 664     let attrs: Vec<_> = attrs.into();
 665     TyParam {
 666         attrs: attrs.into_iter()
 667             .flat_map(|x| fld.fold_attribute(x).into_iter())
 668             .collect::<Vec<_>>()
 669             .into(),
 670         id: fld.new_id(id),
 671         ident: fld.fold_ident(ident),
 672         bounds: fld.fold_bounds(bounds),
 673         default: default.map(|x| fld.fold_ty(x)),
 674         span: fld.new_span(span),
 675     }
 676 }
 677
 678 pub fn noop_fold_ty_params<T: Folder>(tps: Vec<TyParam>, fld: &mut T) -> Vec<TyParam> {
 679     tps.move_map(|tp| fld.fold_ty_param(tp))
 680 }
 681
 682 pub fn noop_fold_lifetime<T: Folder>(l: Lifetime, fld: &mut T) -> Lifetime {
 683     Lifetime {
 684         id: fld.new_id(l.id),
 685         name: l.name,
 686         span: fld.new_span(l.span)
 687     }
 688 }
 689
 690 pub fn noop_fold_lifetime_def<T: Folder>(l: LifetimeDef, fld: &mut T)
 691                                          -> LifetimeDef {
 692     let attrs: Vec<_> = l.attrs.into();
 693     LifetimeDef {
 694         attrs: attrs.into_iter()
 695             .flat_map(|x| fld.fold_attribute(x).into_iter())
 696             .collect::<Vec<_>>()
 697             .into(),
 698         lifetime: fld.fold_lifetime(l.lifetime),
 699         bounds: fld.fold_lifetimes(l.bounds),
 700     }
 701 }
 702
 703 pub fn noop_fold_lifetimes<T: Folder>(lts: Vec<Lifetime>, fld: &mut T) -> Vec<Lifetime> {
 704     lts.move_map(|l| fld.fold_lifetime(l))
 705 }
 706
 707 pub fn noop_fold_lifetime_defs<T: Folder>(lts: Vec<LifetimeDef>, fld: &mut T)
 708                                           -> Vec<LifetimeDef> {
 709     lts.move_map(|l| fld.fold_lifetime_def(l))
 710 }
 711
 712 pub fn noop_fold_opt_lifetime<T: Folder>(o_lt: Option<Lifetime>, fld: &mut T)
 713                                          -> Option<Lifetime> {
 714     o_lt.map(|lt| fld.fold_lifetime(lt))
 715 }
 716
 717 pub fn noop_fold_generics<T: Folder>(Generics {ty_params, lifetimes, where_clause, span}: Generics,
 718                                      fld: &mut T) -> Generics {
 719     Generics {
 720         ty_params: fld.fold_ty_params(ty_params),
 721         lifetimes: fld.fold_lifetime_defs(lifetimes),
 722         where_clause: fld.fold_where_clause(where_clause),
 723         span: fld.new_span(span),
 724     }
 725 }
 726
 727 pub fn noop_fold_where_clause<T: Folder>(
 728                               WhereClause {id, predicates}: WhereClause,
 729                               fld: &mut T)
 730                               -> WhereClause {
 731     WhereClause {
 732         id: fld.new_id(id),
 733         predicates: predicates.move_map(|predicate| {
 734             fld.fold_where_predicate(predicate)
 735         })
 736     }
 737 }
 738
 739 pub fn noop_fold_where_predicate<T: Folder>(
 740                                  pred: WherePredicate,
 741                                  fld: &mut T)
 742                                  -> WherePredicate {
 743     match pred {
 744         ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate{bound_lifetimes,
 745                                                                      bounded_ty,
 746                                                                      bounds,
 747                                                                      span}) => {
 748             ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
 749                 bound_lifetimes: fld.fold_lifetime_defs(bound_lifetimes),
 750                 bounded_ty: fld.fold_ty(bounded_ty),
 751                 bounds: bounds.move_map(|x| fld.fold_ty_param_bound(x)),
 752                 span: fld.new_span(span)
 753             })
 754         }
 755         ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate{lifetime,
 756                                                                        bounds,
 757                                                                        span}) => {
 758             ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
 759                 span: fld.new_span(span),
 760                 lifetime: fld.fold_lifetime(lifetime),
 761                 bounds: bounds.move_map(|bound| fld.fold_lifetime(bound))
 762             })
 763         }
 764         ast::WherePredicate::EqPredicate(ast::WhereEqPredicate{id,
 765                                                                lhs_ty,
 766                                                                rhs_ty,
 767                                                                span}) => {
 768             ast::WherePredicate::EqPredicate(ast::WhereEqPredicate{
 769                 id: fld.new_id(id),
 770                 lhs_ty: fld.fold_ty(lhs_ty),
 771                 rhs_ty: fld.fold_ty(rhs_ty),
 772                 span: fld.new_span(span)
 773             })
 774         }
 775     }
 776 }
 777
 778 pub fn noop_fold_variant_data<T: Folder>(vdata: VariantData, fld: &mut T) -> VariantData {
 779     match vdata {
 780         ast::VariantData::Struct(fields, id) => {
 781             ast::VariantData::Struct(fields.move_map(|f| fld.fold_struct_field(f)),
 782                                      fld.new_id(id))
 783         }
 784         ast::VariantData::Tuple(fields, id) => {
 785             ast::VariantData::Tuple(fields.move_map(|f| fld.fold_struct_field(f)),
 786                                     fld.new_id(id))
 787         }
 788         ast::VariantData::Unit(id) => ast::VariantData::Unit(fld.new_id(id))
 789     }
 790 }
 791
 792 pub fn noop_fold_trait_ref<T: Folder>(p: TraitRef, fld: &mut T) -> TraitRef {
 793     let id = fld.new_id(p.ref_id);
 794     let TraitRef {
 795         path,
 796         ref_id: _,
 797     } = p;
 798     ast::TraitRef {
 799         path: fld.fold_path(path),
 800         ref_id: id,
 801     }
 802 }
 803
 804 pub fn noop_fold_poly_trait_ref<T: Folder>(p: PolyTraitRef, fld: &mut T) -> PolyTraitRef {
 805     ast::PolyTraitRef {
 806         bound_lifetimes: fld.fold_lifetime_defs(p.bound_lifetimes),
 807         trait_ref: fld.fold_trait_ref(p.trait_ref),
 808         span: fld.new_span(p.span),
 809     }
 810 }
 811
 812 pub fn noop_fold_struct_field<T: Folder>(f: StructField, fld: &mut T) -> StructField {
 813     StructField {
 814         span: fld.new_span(f.span),
 815         id: fld.new_id(f.id),
 816         ident: f.ident.map(|ident| fld.fold_ident(ident)),
 817         vis: fld.fold_vis(f.vis),
 818         ty: fld.fold_ty(f.ty),
 819         attrs: fold_attrs(f.attrs, fld),
 820     }
 821 }
 822
 823 pub fn noop_fold_field<T: Folder>(f: Field, folder: &mut T) -> Field {
 824     Field {
 825         ident: respan(f.ident.span, folder.fold_ident(f.ident.node)),
 826         expr: folder.fold_expr(f.expr),
 827         span: folder.new_span(f.span),
 828         is_shorthand: f.is_shorthand,
 829         attrs: fold_thin_attrs(f.attrs, folder),
 830     }
 831 }
 832
 833 pub fn noop_fold_mt<T: Folder>(MutTy {ty, mutbl}: MutTy, folder: &mut T) -> MutTy {
 834     MutTy {
 835         ty: folder.fold_ty(ty),
 836         mutbl: mutbl,
 837     }
 838 }
 839
 840 pub fn noop_fold_opt_bounds<T: Folder>(b: Option<TyParamBounds>, folder: &mut T)
 841                                        -> Option<TyParamBounds> {
 842     b.map(|bounds| folder.fold_bounds(bounds))
 843 }
 844
 845 fn noop_fold_bounds<T: Folder>(bounds: TyParamBounds, folder: &mut T)
 846                           -> TyParamBounds {
 847     bounds.move_map(|bound| folder.fold_ty_param_bound(bound))
 848 }
 849
 850 pub fn noop_fold_block<T: Folder>(b: P<Block>, folder: &mut T) -> P<Block> {
 851     b.map(|Block {id, stmts, rules, span}| Block {
 852         id: folder.new_id(id),
 853         stmts: stmts.move_flat_map(|s| folder.fold_stmt(s).into_iter()),
 854         rules: rules,
 855         span: folder.new_span(span),
 856     })
 857 }
 858
 859 pub fn noop_fold_item_kind<T: Folder>(i: ItemKind, folder: &mut T) -> ItemKind {
 860     match i {
 861         ItemKind::ExternCrate(string) => ItemKind::ExternCrate(string),
 862         ItemKind::Use(view_path) => {
 863             ItemKind::Use(folder.fold_view_path(view_path))
 864         }
 865         ItemKind::Static(t, m, e) => {
 866             ItemKind::Static(folder.fold_ty(t), m, folder.fold_expr(e))
 867         }
 868         ItemKind::Const(t, e) => {
 869             ItemKind::Const(folder.fold_ty(t), folder.fold_expr(e))
 870         }
 871         ItemKind::Fn(decl, unsafety, constness, abi, generics, body) => {
 872             let generics = folder.fold_generics(generics);
 873             let decl = folder.fold_fn_decl(decl);
 874             let body = folder.fold_block(body);
 875             ItemKind::Fn(decl, unsafety, constness, abi, generics, body)
 876         }
 877         ItemKind::Mod(m) => ItemKind::Mod(folder.fold_mod(m)),
 878         ItemKind::ForeignMod(nm) => ItemKind::ForeignMod(folder.fold_foreign_mod(nm)),
 879         ItemKind::GlobalAsm(ga) => ItemKind::GlobalAsm(folder.fold_global_asm(ga)),
 880         ItemKind::Ty(t, generics) => {
 881             ItemKind::Ty(folder.fold_ty(t), folder.fold_generics(generics))
 882         }
 883         ItemKind::Enum(enum_definition, generics) => {
 884             let generics = folder.fold_generics(generics);
 885             let variants = enum_definition.variants.move_map(|x| folder.fold_variant(x));
 886             ItemKind::Enum(ast::EnumDef { variants: variants }, generics)
 887         }
 888         ItemKind::Struct(struct_def, generics) => {
 889             let generics = folder.fold_generics(generics);
 890             ItemKind::Struct(folder.fold_variant_data(struct_def), generics)
 891         }
 892         ItemKind::Union(struct_def, generics) => {
 893             let generics = folder.fold_generics(generics);
 894             ItemKind::Union(folder.fold_variant_data(struct_def), generics)
 895         }
 896         ItemKind::DefaultImpl(unsafety, ref trait_ref) => {
 897             ItemKind::DefaultImpl(unsafety, folder.fold_trait_ref((*trait_ref).clone()))
 898         }
 899         ItemKind::Impl(unsafety, polarity, generics, ifce, ty, impl_items) => ItemKind::Impl(
 900             unsafety,
 901             polarity,
 902             folder.fold_generics(generics),
 903             ifce.map(|trait_ref| folder.fold_trait_ref(trait_ref.clone())),
 904             folder.fold_ty(ty),
 905             impl_items.move_flat_map(|item| folder.fold_impl_item(item)),
 906         ),
 907         ItemKind::Trait(unsafety, generics, bounds, items) => ItemKind::Trait(
 908             unsafety,
 909             folder.fold_generics(generics),
 910             folder.fold_bounds(bounds),
 911             items.move_flat_map(|item| folder.fold_trait_item(item)),
 912         ),
 913         ItemKind::Mac(m) => ItemKind::Mac(folder.fold_mac(m)),
 914         ItemKind::MacroDef(tts) => ItemKind::MacroDef(folder.fold_tts(tts.into()).into()),
 915     }
 916 }
 917
 918 pub fn noop_fold_trait_item<T: Folder>(i: TraitItem, folder: &mut T)
 919                                        -> SmallVector<TraitItem> {
 920     SmallVector::one(TraitItem {
 921         id: folder.new_id(i.id),
 922         ident: folder.fold_ident(i.ident),
 923         attrs: fold_attrs(i.attrs, folder),
 924         node: match i.node {
 925             TraitItemKind::Const(ty, default) => {
 926                 TraitItemKind::Const(folder.fold_ty(ty),
 927                                default.map(|x| folder.fold_expr(x)))
 928             }
 929             TraitItemKind::Method(sig, body) => {
 930                 TraitItemKind::Method(noop_fold_method_sig(sig, folder),
 931                                 body.map(|x| folder.fold_block(x)))
 932             }
 933             TraitItemKind::Type(bounds, default) => {
 934                 TraitItemKind::Type(folder.fold_bounds(bounds),
 935                               default.map(|x| folder.fold_ty(x)))
 936             }
 937             ast::TraitItemKind::Macro(mac) => {
 938                 TraitItemKind::Macro(folder.fold_mac(mac))
 939             }
 940         },
 941         span: folder.new_span(i.span)
 942     })
 943 }
 944
 945 pub fn noop_fold_impl_item<T: Folder>(i: ImplItem, folder: &mut T)
 946                                       -> SmallVector<ImplItem> {
 947     SmallVector::one(ImplItem {
 948         id: folder.new_id(i.id),
 949         vis: folder.fold_vis(i.vis),
 950         ident: folder.fold_ident(i.ident),
 951         attrs: fold_attrs(i.attrs, folder),
 952         defaultness: i.defaultness,
 953         node: match i.node  {
 954             ast::ImplItemKind::Const(ty, expr) => {
 955                 ast::ImplItemKind::Const(folder.fold_ty(ty), folder.fold_expr(expr))
 956             }
 957             ast::ImplItemKind::Method(sig, body) => {
 958                 ast::ImplItemKind::Method(noop_fold_method_sig(sig, folder),
 959                                folder.fold_block(body))
 960             }
 961             ast::ImplItemKind::Type(ty) => ast::ImplItemKind::Type(folder.fold_ty(ty)),
 962             ast::ImplItemKind::Macro(mac) => ast::ImplItemKind::Macro(folder.fold_mac(mac))
 963         },
 964         span: folder.new_span(i.span)
 965     })
 966 }
 967
 968 pub fn noop_fold_mod<T: Folder>(Mod {inner, items}: Mod, folder: &mut T) -> Mod {
 969     Mod {
 970         inner: folder.new_span(inner),
 971         items: items.move_flat_map(|x| folder.fold_item(x)),
 972     }
 973 }
 974
 975 pub fn noop_fold_crate<T: Folder>(Crate {module, attrs, span}: Crate,
 976                                   folder: &mut T) -> Crate {
 977     let mut items = folder.fold_item(P(ast::Item {
 978         ident: keywords::Invalid.ident(),
 979         attrs: attrs,
 980         id: ast::DUMMY_NODE_ID,
 981         vis: ast::Visibility::Public,
 982         span: span,
 983         node: ast::ItemKind::Mod(module),
 984     })).into_iter();
 985
 986     let (module, attrs, span) = match items.next() {
 987         Some(item) => {
 988             assert!(items.next().is_none(),
 989                     "a crate cannot expand to more than one item");
 990             item.and_then(|ast::Item { attrs, span, node, .. }| {
 991                 match node {
 992                     ast::ItemKind::Mod(m) => (m, attrs, span),
 993                     _ => panic!("fold converted a module to not a module"),
 994                 }
 995             })
 996         }
 997         None => (ast::Mod {
 998             inner: span,
 999             items: vec![],
1000         }, vec![], span)
1001     };
1002
1003     Crate {
1004         module: module,
1005         attrs: attrs,
1006         span: span,
1007     }
1008 }
1009
1010 // fold one item into possibly many items
1011 pub fn noop_fold_item<T: Folder>(i: P<Item>, folder: &mut T) -> SmallVector<P<Item>> {
1012     SmallVector::one(i.map(|i| folder.fold_item_simple(i)))
1013 }
1014
1015 // fold one item into exactly one item
1016 pub fn noop_fold_item_simple<T: Folder>(Item {id, ident, attrs, node, vis, span}: Item,
1017                                         folder: &mut T) -> Item {
1018     Item {
1019         id: folder.new_id(id),
1020         vis: folder.fold_vis(vis),
1021         ident: folder.fold_ident(ident),
1022         attrs: fold_attrs(attrs, folder),
1023         node: folder.fold_item_kind(node),
1024         span: folder.new_span(span)
1025     }
1026 }
1027
1028 pub fn noop_fold_foreign_item<T: Folder>(ni: ForeignItem, folder: &mut T) -> ForeignItem {
1029     ForeignItem {
1030         id: folder.new_id(ni.id),
1031         vis: folder.fold_vis(ni.vis),
1032         ident: folder.fold_ident(ni.ident),
1033         attrs: fold_attrs(ni.attrs, folder),
1034         node: match ni.node {
1035             ForeignItemKind::Fn(fdec, generics) => {
1036                 ForeignItemKind::Fn(folder.fold_fn_decl(fdec), folder.fold_generics(generics))
1037             }
1038             ForeignItemKind::Static(t, m) => {
1039                 ForeignItemKind::Static(folder.fold_ty(t), m)
1040             }
1041         },
1042         span: folder.new_span(ni.span)
1043     }
1044 }
1045
1046 pub fn noop_fold_method_sig<T: Folder>(sig: MethodSig, folder: &mut T) -> MethodSig {
1047     MethodSig {
1048         generics: folder.fold_generics(sig.generics),
1049         abi: sig.abi,
1050         unsafety: sig.unsafety,
1051         constness: sig.constness,
1052         decl: folder.fold_fn_decl(sig.decl)
1053     }
1054 }
1055
1056 pub fn noop_fold_pat<T: Folder>(p: P<Pat>, folder: &mut T) -> P<Pat> {
1057     p.map(|Pat {id, node, span}| Pat {
1058         id: folder.new_id(id),
1059         node: match node {
1060             PatKind::Wild => PatKind::Wild,
1061             PatKind::Ident(binding_mode, pth1, sub) => {
1062                 PatKind::Ident(binding_mode,
1063                         Spanned{span: folder.new_span(pth1.span),
1064                                 node: folder.fold_ident(pth1.node)},
1065                         sub.map(|x| folder.fold_pat(x)))
1066             }
1067             PatKind::Lit(e) => PatKind::Lit(folder.fold_expr(e)),
1068             PatKind::TupleStruct(pth, pats, ddpos) => {
1069                 PatKind::TupleStruct(folder.fold_path(pth),
1070                         pats.move_map(|x| folder.fold_pat(x)), ddpos)
1071             }
1072             PatKind::Path(opt_qself, pth) => {
1073                 let opt_qself = opt_qself.map(|qself| {
1074                     QSelf { ty: folder.fold_ty(qself.ty), position: qself.position }
1075                 });
1076                 PatKind::Path(opt_qself, folder.fold_path(pth))
1077             }
1078             PatKind::Struct(pth, fields, etc) => {
1079                 let pth = folder.fold_path(pth);
1080                 let fs = fields.move_map(|f| {
1081                     Spanned { span: folder.new_span(f.span),
1082                               node: ast::FieldPat {
1083                                   ident: folder.fold_ident(f.node.ident),
1084                                   pat: folder.fold_pat(f.node.pat),
1085                                   is_shorthand: f.node.is_shorthand,
1086                                   attrs: fold_attrs(f.node.attrs.into(), folder).into()
1087                               }}
1088                 });
1089                 PatKind::Struct(pth, fs, etc)
1090             }
1091             PatKind::Tuple(elts, ddpos) => {
1092                 PatKind::Tuple(elts.move_map(|x| folder.fold_pat(x)), ddpos)
1093             }
1094             PatKind::Box(inner) => PatKind::Box(folder.fold_pat(inner)),
1095             PatKind::Ref(inner, mutbl) => PatKind::Ref(folder.fold_pat(inner), mutbl),
1096             PatKind::Range(e1, e2, end) => {
1097                 PatKind::Range(folder.fold_expr(e1),
1098                                folder.fold_expr(e2),
1099                                folder.fold_range_end(end))
1100             },
1101             PatKind::Slice(before, slice, after) => {
1102                 PatKind::Slice(before.move_map(|x| folder.fold_pat(x)),
1103                        slice.map(|x| folder.fold_pat(x)),
1104                        after.move_map(|x| folder.fold_pat(x)))
1105             }
1106             PatKind::Mac(mac) => PatKind::Mac(folder.fold_mac(mac))
1107         },
1108         span: folder.new_span(span)
1109     })
1110 }
1111
1112 pub fn noop_fold_range_end<T: Folder>(end: RangeEnd, _folder: &mut T) -> RangeEnd {
1113     end
1114 }
1115
1116 pub fn noop_fold_expr<T: Folder>(Expr {id, node, span, attrs}: Expr, folder: &mut T) -> Expr {
1117     Expr {
1118         node: match node {
1119             ExprKind::Box(e) => {
1120                 ExprKind::Box(folder.fold_expr(e))
1121             }
1122             ExprKind::InPlace(p, e) => {
1123                 ExprKind::InPlace(folder.fold_expr(p), folder.fold_expr(e))
1124             }
1125             ExprKind::Array(exprs) => {
1126                 ExprKind::Array(folder.fold_exprs(exprs))
1127             }
1128             ExprKind::Repeat(expr, count) => {
1129                 ExprKind::Repeat(folder.fold_expr(expr), folder.fold_expr(count))
1130             }
1131             ExprKind::Tup(exprs) => ExprKind::Tup(folder.fold_exprs(exprs)),
1132             ExprKind::Call(f, args) => {
1133                 ExprKind::Call(folder.fold_expr(f),
1134                          folder.fold_exprs(args))
1135             }
1136             ExprKind::MethodCall(i, tps, args) => {
1137                 ExprKind::MethodCall(
1138                     respan(folder.new_span(i.span), folder.fold_ident(i.node)),
1139                     tps.move_map(|x| folder.fold_ty(x)),
1140                     folder.fold_exprs(args))
1141             }
1142             ExprKind::Binary(binop, lhs, rhs) => {
1143                 ExprKind::Binary(binop,
1144                         folder.fold_expr(lhs),
1145                         folder.fold_expr(rhs))
1146             }
1147             ExprKind::Unary(binop, ohs) => {
1148                 ExprKind::Unary(binop, folder.fold_expr(ohs))
1149             }
1150             ExprKind::Lit(l) => ExprKind::Lit(l),
1151             ExprKind::Cast(expr, ty) => {
1152                 ExprKind::Cast(folder.fold_expr(expr), folder.fold_ty(ty))
1153             }
1154             ExprKind::Type(expr, ty) => {
1155                 ExprKind::Type(folder.fold_expr(expr), folder.fold_ty(ty))
1156             }
1157             ExprKind::AddrOf(m, ohs) => ExprKind::AddrOf(m, folder.fold_expr(ohs)),
1158             ExprKind::If(cond, tr, fl) => {
1159                 ExprKind::If(folder.fold_expr(cond),
1160                        folder.fold_block(tr),
1161                        fl.map(|x| folder.fold_expr(x)))
1162             }
1163             ExprKind::IfLet(pat, expr, tr, fl) => {
1164                 ExprKind::IfLet(folder.fold_pat(pat),
1165                           folder.fold_expr(expr),
1166                           folder.fold_block(tr),
1167                           fl.map(|x| folder.fold_expr(x)))
1168             }
1169             ExprKind::While(cond, body, opt_ident) => {
1170                 ExprKind::While(folder.fold_expr(cond),
1171                           folder.fold_block(body),
1172                           opt_ident.map(|label| respan(folder.new_span(label.span),
1173                                                        folder.fold_ident(label.node))))
1174             }
1175             ExprKind::WhileLet(pat, expr, body, opt_ident) => {
1176                 ExprKind::WhileLet(folder.fold_pat(pat),
1177                              folder.fold_expr(expr),
1178                              folder.fold_block(body),
1179                              opt_ident.map(|label| respan(folder.new_span(label.span),
1180                                                           folder.fold_ident(label.node))))
1181             }
1182             ExprKind::ForLoop(pat, iter, body, opt_ident) => {
1183                 ExprKind::ForLoop(folder.fold_pat(pat),
1184                             folder.fold_expr(iter),
1185                             folder.fold_block(body),
1186                             opt_ident.map(|label| respan(folder.new_span(label.span),
1187                                                          folder.fold_ident(label.node))))
1188             }
1189             ExprKind::Loop(body, opt_ident) => {
1190                 ExprKind::Loop(folder.fold_block(body),
1191                                opt_ident.map(|label| respan(folder.new_span(label.span),
1192                                                             folder.fold_ident(label.node))))
1193             }
1194             ExprKind::Match(expr, arms) => {
1195                 ExprKind::Match(folder.fold_expr(expr),
1196                           arms.move_map(|x| folder.fold_arm(x)))
1197             }
1198             ExprKind::Closure(capture_clause, decl, body, span) => {
1199                 ExprKind::Closure(capture_clause,
1200                                   folder.fold_fn_decl(decl),
1201                                   folder.fold_expr(body),
1202                                   folder.new_span(span))
1203             }
1204             ExprKind::Block(blk) => ExprKind::Block(folder.fold_block(blk)),
1205             ExprKind::Assign(el, er) => {
1206                 ExprKind::Assign(folder.fold_expr(el), folder.fold_expr(er))
1207             }
1208             ExprKind::AssignOp(op, el, er) => {
1209                 ExprKind::AssignOp(op,
1210                             folder.fold_expr(el),
1211                             folder.fold_expr(er))
1212             }
1213             ExprKind::Field(el, ident) => {
1214                 ExprKind::Field(folder.fold_expr(el),
1215                           respan(folder.new_span(ident.span),
1216                                  folder.fold_ident(ident.node)))
1217             }
1218             ExprKind::TupField(el, ident) => {
1219                 ExprKind::TupField(folder.fold_expr(el),
1220                              respan(folder.new_span(ident.span),
1221                                     folder.fold_usize(ident.node)))
1222             }
1223             ExprKind::Index(el, er) => {
1224                 ExprKind::Index(folder.fold_expr(el), folder.fold_expr(er))
1225             }
1226             ExprKind::Range(e1, e2, lim) => {
1227                 ExprKind::Range(e1.map(|x| folder.fold_expr(x)),
1228                                 e2.map(|x| folder.fold_expr(x)),
1229                                 lim)
1230             }
1231             ExprKind::Path(qself, path) => {
1232                 let qself = qself.map(|QSelf { ty, position }| {
1233                     QSelf {
1234                         ty: folder.fold_ty(ty),
1235                         position: position
1236                     }
1237                 });
1238                 ExprKind::Path(qself, folder.fold_path(path))
1239             }
1240             ExprKind::Break(opt_ident, opt_expr) => {
1241                 ExprKind::Break(opt_ident.map(|label| respan(folder.new_span(label.span),
1242                                                              folder.fold_ident(label.node))),
1243                                 opt_expr.map(|e| folder.fold_expr(e)))
1244             }
1245             ExprKind::Continue(opt_ident) => ExprKind::Continue(opt_ident.map(|label|
1246                 respan(folder.new_span(label.span),
1247                        folder.fold_ident(label.node)))
1248             ),
1249             ExprKind::Ret(e) => ExprKind::Ret(e.map(|x| folder.fold_expr(x))),
1250             ExprKind::InlineAsm(asm) => ExprKind::InlineAsm(asm.map(|asm| {
1251                 InlineAsm {
1252                     inputs: asm.inputs.move_map(|(c, input)| {
1253                         (c, folder.fold_expr(input))
1254                     }),
1255                     outputs: asm.outputs.move_map(|out| {
1256                         InlineAsmOutput {
1257                             constraint: out.constraint,
1258                             expr: folder.fold_expr(out.expr),
1259                             is_rw: out.is_rw,
1260                             is_indirect: out.is_indirect,
1261                         }
1262                     }),
1263                     ..asm
1264                 }
1265             })),
1266             ExprKind::Mac(mac) => ExprKind::Mac(folder.fold_mac(mac)),
1267             ExprKind::Struct(path, fields, maybe_expr) => {
1268                 ExprKind::Struct(folder.fold_path(path),
1269                         fields.move_map(|x| folder.fold_field(x)),
1270                         maybe_expr.map(|x| folder.fold_expr(x)))
1271             },
1272             ExprKind::Paren(ex) => {
1273                 let sub_expr = folder.fold_expr(ex);
1274                 return Expr {
1275                     // Nodes that are equal modulo `Paren` sugar no-ops should have the same ids.
1276                     id: sub_expr.id,
1277                     node: ExprKind::Paren(sub_expr),
1278                     span: folder.new_span(span),
1279                     attrs: fold_attrs(attrs.into(), folder).into(),
1280                 };
1281             }
1282             ExprKind::Try(ex) => ExprKind::Try(folder.fold_expr(ex)),
1283             ExprKind::Catch(body) => ExprKind::Catch(folder.fold_block(body)),
1284         },
1285         id: folder.new_id(id),
1286         span: folder.new_span(span),
1287         attrs: fold_attrs(attrs.into(), folder).into(),
1288     }
1289 }
1290
1291 pub fn noop_fold_opt_expr<T: Folder>(e: P<Expr>, folder: &mut T) -> Option<P<Expr>> {
1292     Some(folder.fold_expr(e))
1293 }
1294
1295 pub fn noop_fold_exprs<T: Folder>(es: Vec<P<Expr>>, folder: &mut T) -> Vec<P<Expr>> {
1296     es.move_flat_map(|e| folder.fold_opt_expr(e))
1297 }
1298
1299 pub fn noop_fold_stmt<T: Folder>(Stmt {node, span, id}: Stmt, folder: &mut T) -> SmallVector<Stmt> {
1300     let id = folder.new_id(id);
1301     let span = folder.new_span(span);
1302     noop_fold_stmt_kind(node, folder).into_iter().map(|node| {
1303         Stmt { id: id, node: node, span: span }
1304     }).collect()
1305 }
1306
1307 pub fn noop_fold_stmt_kind<T: Folder>(node: StmtKind, folder: &mut T) -> SmallVector<StmtKind> {
1308     match node {
1309         StmtKind::Local(local) => SmallVector::one(StmtKind::Local(folder.fold_local(local))),
1310         StmtKind::Item(item) => folder.fold_item(item).into_iter().map(StmtKind::Item).collect(),
1311         StmtKind::Expr(expr) => {
1312             folder.fold_opt_expr(expr).into_iter().map(StmtKind::Expr).collect()
1313         }
1314         StmtKind::Semi(expr) => {
1315             folder.fold_opt_expr(expr).into_iter().map(StmtKind::Semi).collect()
1316         }
1317         StmtKind::Mac(mac) => SmallVector::one(StmtKind::Mac(mac.map(|(mac, semi, attrs)| {
1318             (folder.fold_mac(mac), semi, fold_attrs(attrs.into(), folder).into())
1319         }))),
1320     }
1321 }
1322
1323 pub fn noop_fold_vis<T: Folder>(vis: Visibility, folder: &mut T) -> Visibility {
1324     match vis {
1325         Visibility::Restricted { path, id } => Visibility::Restricted {
1326             path: path.map(|path| folder.fold_path(path)),
1327             id: folder.new_id(id)
1328         },
1329         _ => vis,
1330     }
1331 }
1332
1333 #[cfg(test)]
1334 mod tests {
1335     use std::io;
1336     use ast::{self, Ident};
1337     use util::parser_testing::{string_to_crate, matches_codepattern};
1338     use print::pprust;
1339     use fold;
1340     use super::*;
1341
1342     // this version doesn't care about getting comments or docstrings in.
1343     fn fake_print_crate(s: &mut pprust::State,
1344                         krate: &ast::Crate) -> io::Result<()> {
1345         s.print_mod(&krate.module, &krate.attrs)
1346     }
1347
1348     // change every identifier to "zz"
1349     struct ToZzIdentFolder;
1350
1351     impl Folder for ToZzIdentFolder {
1352         fn fold_ident(&mut self, _: ast::Ident) -> ast::Ident {
1353             Ident::from_str("zz")
1354         }
1355         fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
1356             fold::noop_fold_mac(mac, self)
1357         }
1358     }
1359
1360     // maybe add to expand.rs...
1361     macro_rules! assert_pred {
1362         ($pred:expr, $predname:expr, $a:expr , $b:expr) => (
1363             {
1364                 let pred_val = $pred;
1365                 let a_val = $a;
1366                 let b_val = $b;
1367                 if !(pred_val(&a_val, &b_val)) {
1368                     panic!("expected args satisfying {}, got {} and {}",
1369                           $predname, a_val, b_val);
1370                 }
1371             }
1372         )
1373     }
1374
1375     // make sure idents get transformed everywhere
1376     #[test] fn ident_transformation () {
1377         let mut zz_fold = ToZzIdentFolder;
1378         let ast = string_to_crate(
1379             "#[a] mod b {fn c (d : e, f : g) {h!(i,j,k);l;m}}".to_string());
1380         let folded_crate = zz_fold.fold_crate(ast);
1381         assert_pred!(
1382             matches_codepattern,
1383             "matches_codepattern",
1384             pprust::to_string(|s| fake_print_crate(s, &folded_crate)),
1385             "#[zz]mod zz{fn zz(zz:zz,zz:zz){zz!(zz,zz,zz);zz;zz}}".to_string());
1386     }
1387
1388     // even inside macro defs....
1389     #[test] fn ident_transformation_in_defs () {
1390         let mut zz_fold = ToZzIdentFolder;
1391         let ast = string_to_crate(
1392             "macro_rules! a {(b $c:expr $(d $e:token)f+ => \
1393              (g $(d $d $e)+))} ".to_string());
1394         let folded_crate = zz_fold.fold_crate(ast);
1395         assert_pred!(
1396             matches_codepattern,
1397             "matches_codepattern",
1398             pprust::to_string(|s| fake_print_crate(s, &folded_crate)),
1399             "macro_rules! zz((zz$zz:zz$(zz $zz:zz)zz+=>(zz$(zz$zz$zz)+)));".to_string());
1400     }
1401 }