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::{self, 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_use_tree(&mut self, use_tree: UseTree) -> UseTree {
  60         noop_fold_use_tree(use_tree, 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_macro_def(&mut self, def: MacroDef) -> MacroDef {
 193         noop_fold_macro_def(def, self)
 194     }
 195
 196     fn fold_label(&mut self, label: Label) -> Label {
 197         noop_fold_label(label, self)
 198     }
 199
 200     fn fold_lifetime(&mut self, l: Lifetime) -> Lifetime {
 201         noop_fold_lifetime(l, self)
 202     }
 203
 204     fn fold_lifetime_def(&mut self, l: LifetimeDef) -> LifetimeDef {
 205         noop_fold_lifetime_def(l, self)
 206     }
 207
 208     fn fold_attribute(&mut self, at: Attribute) -> Option<Attribute> {
 209         noop_fold_attribute(at, self)
 210     }
 211
 212     fn fold_arg(&mut self, a: Arg) -> Arg {
 213         noop_fold_arg(a, self)
 214     }
 215
 216     fn fold_generics(&mut self, generics: Generics) -> Generics {
 217         noop_fold_generics(generics, self)
 218     }
 219
 220     fn fold_trait_ref(&mut self, p: TraitRef) -> TraitRef {
 221         noop_fold_trait_ref(p, self)
 222     }
 223
 224     fn fold_poly_trait_ref(&mut self, p: PolyTraitRef) -> PolyTraitRef {
 225         noop_fold_poly_trait_ref(p, self)
 226     }
 227
 228     fn fold_variant_data(&mut self, vdata: VariantData) -> VariantData {
 229         noop_fold_variant_data(vdata, self)
 230     }
 231
 232     fn fold_lifetimes(&mut self, lts: Vec<Lifetime>) -> Vec<Lifetime> {
 233         noop_fold_lifetimes(lts, self)
 234     }
 235
 236     fn fold_lifetime_defs(&mut self, lts: Vec<LifetimeDef>) -> Vec<LifetimeDef> {
 237         noop_fold_lifetime_defs(lts, self)
 238     }
 239
 240     fn fold_ty_param(&mut self, tp: TyParam) -> TyParam {
 241         noop_fold_ty_param(tp, self)
 242     }
 243
 244     fn fold_generic_param(&mut self, param: GenericParam) -> GenericParam {
 245         noop_fold_generic_param(param, self)
 246     }
 247
 248     fn fold_generic_params(&mut self, params: Vec<GenericParam>) -> Vec<GenericParam> {
 249         noop_fold_generic_params(params, self)
 250     }
 251
 252     fn fold_tt(&mut self, tt: TokenTree) -> TokenTree {
 253         noop_fold_tt(tt, self)
 254     }
 255
 256     fn fold_tts(&mut self, tts: TokenStream) -> TokenStream {
 257         noop_fold_tts(tts, self)
 258     }
 259
 260     fn fold_token(&mut self, t: token::Token) -> token::Token {
 261         noop_fold_token(t, self)
 262     }
 263
 264     fn fold_interpolated(&mut self, nt: token::Nonterminal) -> token::Nonterminal {
 265         noop_fold_interpolated(nt, self)
 266     }
 267
 268     fn fold_opt_lifetime(&mut self, o_lt: Option<Lifetime>) -> Option<Lifetime> {
 269         noop_fold_opt_lifetime(o_lt, self)
 270     }
 271
 272     fn fold_opt_bounds(&mut self, b: Option<TyParamBounds>)
 273                        -> Option<TyParamBounds> {
 274         noop_fold_opt_bounds(b, self)
 275     }
 276
 277     fn fold_bounds(&mut self, b: TyParamBounds)
 278                        -> TyParamBounds {
 279         noop_fold_bounds(b, self)
 280     }
 281
 282     fn fold_ty_param_bound(&mut self, tpb: TyParamBound) -> TyParamBound {
 283         noop_fold_ty_param_bound(tpb, self)
 284     }
 285
 286     fn fold_mt(&mut self, mt: MutTy) -> MutTy {
 287         noop_fold_mt(mt, self)
 288     }
 289
 290     fn fold_field(&mut self, field: Field) -> Field {
 291         noop_fold_field(field, self)
 292     }
 293
 294     fn fold_where_clause(&mut self, where_clause: WhereClause)
 295                          -> WhereClause {
 296         noop_fold_where_clause(where_clause, self)
 297     }
 298
 299     fn fold_where_predicate(&mut self, where_predicate: WherePredicate)
 300                             -> WherePredicate {
 301         noop_fold_where_predicate(where_predicate, self)
 302     }
 303
 304     fn fold_vis(&mut self, vis: Visibility) -> Visibility {
 305         noop_fold_vis(vis, self)
 306     }
 307
 308     fn new_id(&mut self, i: NodeId) -> NodeId {
 309         i
 310     }
 311
 312     fn new_span(&mut self, sp: Span) -> Span {
 313         sp
 314     }
 315 }
 316
 317 pub fn noop_fold_meta_items<T: Folder>(meta_items: Vec<MetaItem>, fld: &mut T) -> Vec<MetaItem> {
 318     meta_items.move_map(|x| fld.fold_meta_item(x))
 319 }
 320
 321 pub fn noop_fold_use_tree<T: Folder>(use_tree: UseTree, fld: &mut T) -> UseTree {
 322     UseTree {
 323         span: fld.new_span(use_tree.span),
 324         prefix: fld.fold_path(use_tree.prefix),
 325         kind: match use_tree.kind {
 326             UseTreeKind::Simple(ident) => UseTreeKind::Simple(fld.fold_ident(ident)),
 327             UseTreeKind::Glob => UseTreeKind::Glob,
 328             UseTreeKind::Nested(items) => UseTreeKind::Nested(items.move_map(|(tree, id)| {
 329                 (fld.fold_use_tree(tree), fld.new_id(id))
 330             })),
 331         },
 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,
 344     fld: &mut T) -> Arm {
 345     Arm {
 346         attrs: fold_attrs(attrs, fld),
 347         pats: pats.move_map(|x| fld.fold_pat(x)),
 348         guard: guard.map(|x| fld.fold_expr(x)),
 349         body: fld.fold_expr(body),
 350     }
 351 }
 352
 353 pub fn noop_fold_ty_binding<T: Folder>(b: TypeBinding, fld: &mut T) -> TypeBinding {
 354     TypeBinding {
 355         id: fld.new_id(b.id),
 356         ident: fld.fold_ident(b.ident),
 357         ty: fld.fold_ty(b.ty),
 358         span: fld.new_span(b.span),
 359     }
 360 }
 361
 362 pub fn noop_fold_ty<T: Folder>(t: P<Ty>, fld: &mut T) -> P<Ty> {
 363     t.map(|Ty {id, node, span}| Ty {
 364         id: fld.new_id(id),
 365         node: match node {
 366             TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err => node,
 367             TyKind::Slice(ty) => TyKind::Slice(fld.fold_ty(ty)),
 368             TyKind::Ptr(mt) => TyKind::Ptr(fld.fold_mt(mt)),
 369             TyKind::Rptr(region, mt) => {
 370                 TyKind::Rptr(fld.fold_opt_lifetime(region), fld.fold_mt(mt))
 371             }
 372             TyKind::BareFn(f) => {
 373                 TyKind::BareFn(f.map(|BareFnTy {generic_params, unsafety, abi, decl}| BareFnTy {
 374                     generic_params: fld.fold_generic_params(generic_params),
 375                     unsafety,
 376                     abi,
 377                     decl: fld.fold_fn_decl(decl)
 378                 }))
 379             }
 380             TyKind::Never => node,
 381             TyKind::Tup(tys) => TyKind::Tup(tys.move_map(|ty| fld.fold_ty(ty))),
 382             TyKind::Paren(ty) => TyKind::Paren(fld.fold_ty(ty)),
 383             TyKind::Path(qself, path) => {
 384                 let qself = qself.map(|QSelf { ty, position }| {
 385                     QSelf {
 386                         ty: fld.fold_ty(ty),
 387                         position,
 388                     }
 389                 });
 390                 TyKind::Path(qself, fld.fold_path(path))
 391             }
 392             TyKind::Array(ty, e) => {
 393                 TyKind::Array(fld.fold_ty(ty), fld.fold_expr(e))
 394             }
 395             TyKind::Typeof(expr) => {
 396                 TyKind::Typeof(fld.fold_expr(expr))
 397             }
 398             TyKind::TraitObject(bounds, syntax) => {
 399                 TyKind::TraitObject(bounds.move_map(|b| fld.fold_ty_param_bound(b)), syntax)
 400             }
 401             TyKind::ImplTrait(bounds) => {
 402                 TyKind::ImplTrait(bounds.move_map(|b| fld.fold_ty_param_bound(b)))
 403             }
 404             TyKind::Mac(mac) => {
 405                 TyKind::Mac(fld.fold_mac(mac))
 406             }
 407         },
 408         span: fld.new_span(span)
 409     })
 410 }
 411
 412 pub fn noop_fold_foreign_mod<T: Folder>(ForeignMod {abi, items}: ForeignMod,
 413                                         fld: &mut T) -> ForeignMod {
 414     ForeignMod {
 415         abi,
 416         items: items.move_map(|x| fld.fold_foreign_item(x)),
 417     }
 418 }
 419
 420 pub fn noop_fold_global_asm<T: Folder>(ga: P<GlobalAsm>,
 421                                        _: &mut T) -> P<GlobalAsm> {
 422     ga
 423 }
 424
 425 pub fn noop_fold_variant<T: Folder>(v: Variant, fld: &mut T) -> Variant {
 426     Spanned {
 427         node: Variant_ {
 428             name: fld.fold_ident(v.node.name),
 429             attrs: fold_attrs(v.node.attrs, fld),
 430             data: fld.fold_variant_data(v.node.data),
 431             disr_expr: v.node.disr_expr.map(|e| fld.fold_expr(e)),
 432         },
 433         span: fld.new_span(v.span),
 434     }
 435 }
 436
 437 pub fn noop_fold_ident<T: Folder>(i: Ident, _: &mut T) -> Ident {
 438     i
 439 }
 440
 441 pub fn noop_fold_usize<T: Folder>(i: usize, _: &mut T) -> usize {
 442     i
 443 }
 444
 445 pub fn noop_fold_path<T: Folder>(Path { segments, span }: Path, fld: &mut T) -> Path {
 446     Path {
 447         segments: segments.move_map(|PathSegment {identifier, span, parameters}| PathSegment {
 448             identifier: fld.fold_ident(identifier),
 449             span: fld.new_span(span),
 450             parameters: parameters.map(|ps| ps.map(|ps| fld.fold_path_parameters(ps))),
 451         }),
 452         span: fld.new_span(span)
 453     }
 454 }
 455
 456 pub fn noop_fold_path_parameters<T: Folder>(path_parameters: PathParameters, fld: &mut T)
 457                                             -> PathParameters
 458 {
 459     match path_parameters {
 460         PathParameters::AngleBracketed(data) =>
 461             PathParameters::AngleBracketed(fld.fold_angle_bracketed_parameter_data(data)),
 462         PathParameters::Parenthesized(data) =>
 463             PathParameters::Parenthesized(fld.fold_parenthesized_parameter_data(data)),
 464     }
 465 }
 466
 467 pub fn noop_fold_angle_bracketed_parameter_data<T: Folder>(data: AngleBracketedParameterData,
 468                                                            fld: &mut T)
 469                                                            -> AngleBracketedParameterData
 470 {
 471     let AngleBracketedParameterData { lifetimes, types, bindings, span } = data;
 472     AngleBracketedParameterData { lifetimes: fld.fold_lifetimes(lifetimes),
 473                                   types: types.move_map(|ty| fld.fold_ty(ty)),
 474                                   bindings: bindings.move_map(|b| fld.fold_ty_binding(b)),
 475                                   span: fld.new_span(span) }
 476 }
 477
 478 pub fn noop_fold_parenthesized_parameter_data<T: Folder>(data: ParenthesizedParameterData,
 479                                                          fld: &mut T)
 480                                                          -> ParenthesizedParameterData
 481 {
 482     let ParenthesizedParameterData { inputs, output, span } = data;
 483     ParenthesizedParameterData { inputs: inputs.move_map(|ty| fld.fold_ty(ty)),
 484                                  output: output.map(|ty| fld.fold_ty(ty)),
 485                                  span: fld.new_span(span) }
 486 }
 487
 488 pub fn noop_fold_local<T: Folder>(l: P<Local>, fld: &mut T) -> P<Local> {
 489     l.map(|Local {id, pat, ty, init, span, attrs}| Local {
 490         id: fld.new_id(id),
 491         pat: fld.fold_pat(pat),
 492         ty: ty.map(|t| fld.fold_ty(t)),
 493         init: init.map(|e| fld.fold_expr(e)),
 494         span: fld.new_span(span),
 495         attrs: fold_attrs(attrs.into(), fld).into(),
 496     })
 497 }
 498
 499 pub fn noop_fold_attribute<T: Folder>(attr: Attribute, fld: &mut T) -> Option<Attribute> {
 500     Some(Attribute {
 501         id: attr.id,
 502         style: attr.style,
 503         path: fld.fold_path(attr.path),
 504         tokens: fld.fold_tts(attr.tokens),
 505         is_sugared_doc: attr.is_sugared_doc,
 506         span: fld.new_span(attr.span),
 507     })
 508 }
 509
 510 pub fn noop_fold_mac<T: Folder>(Spanned {node, span}: Mac, fld: &mut T) -> Mac {
 511     Spanned {
 512         node: Mac_ {
 513             tts: fld.fold_tts(node.stream()).into(),
 514             path: fld.fold_path(node.path),
 515         },
 516         span: fld.new_span(span)
 517     }
 518 }
 519
 520 pub fn noop_fold_macro_def<T: Folder>(def: MacroDef, fld: &mut T) -> MacroDef {
 521     MacroDef {
 522         tokens: fld.fold_tts(def.tokens.into()).into(),
 523         legacy: def.legacy,
 524     }
 525 }
 526
 527 pub fn noop_fold_meta_list_item<T: Folder>(li: NestedMetaItem, fld: &mut T)
 528     -> NestedMetaItem {
 529     Spanned {
 530         node: match li.node {
 531             NestedMetaItemKind::MetaItem(mi) =>  {
 532                 NestedMetaItemKind::MetaItem(fld.fold_meta_item(mi))
 533             },
 534             NestedMetaItemKind::Literal(lit) => NestedMetaItemKind::Literal(lit)
 535         },
 536         span: fld.new_span(li.span)
 537     }
 538 }
 539
 540 pub fn noop_fold_meta_item<T: Folder>(mi: MetaItem, fld: &mut T) -> MetaItem {
 541     MetaItem {
 542         name: mi.name,
 543         node: match mi.node {
 544             MetaItemKind::Word => MetaItemKind::Word,
 545             MetaItemKind::List(mis) => {
 546                 MetaItemKind::List(mis.move_map(|e| fld.fold_meta_list_item(e)))
 547             },
 548             MetaItemKind::NameValue(s) => MetaItemKind::NameValue(s),
 549         },
 550         span: fld.new_span(mi.span)
 551     }
 552 }
 553
 554 pub fn noop_fold_arg<T: Folder>(Arg {id, pat, ty}: Arg, fld: &mut T) -> Arg {
 555     Arg {
 556         id: fld.new_id(id),
 557         pat: fld.fold_pat(pat),
 558         ty: fld.fold_ty(ty)
 559     }
 560 }
 561
 562 pub fn noop_fold_tt<T: Folder>(tt: TokenTree, fld: &mut T) -> TokenTree {
 563     match tt {
 564         TokenTree::Token(span, tok) =>
 565             TokenTree::Token(fld.new_span(span), fld.fold_token(tok)),
 566         TokenTree::Delimited(span, delimed) => TokenTree::Delimited(fld.new_span(span), Delimited {
 567             tts: fld.fold_tts(delimed.stream()).into(),
 568             delim: delimed.delim,
 569         }),
 570     }
 571 }
 572
 573 pub fn noop_fold_tts<T: Folder>(tts: TokenStream, fld: &mut T) -> TokenStream {
 574     tts.map(|tt| fld.fold_tt(tt))
 575 }
 576
 577 // apply ident folder if it's an ident, apply other folds to interpolated nodes
 578 pub fn noop_fold_token<T: Folder>(t: token::Token, fld: &mut T) -> token::Token {
 579     match t {
 580         token::Ident(id) => token::Ident(fld.fold_ident(id)),
 581         token::Lifetime(id) => token::Lifetime(fld.fold_ident(id)),
 582         token::Interpolated(nt) => {
 583             let nt = match Rc::try_unwrap(nt) {
 584                 Ok(nt) => nt,
 585                 Err(nt) => (*nt).clone(),
 586             };
 587             Token::interpolated(fld.fold_interpolated(nt.0))
 588         }
 589         _ => t
 590     }
 591 }
 592
 593 /// apply folder to elements of interpolated nodes
 594 //
 595 // NB: this can occur only when applying a fold to partially expanded code, where
 596 // parsed pieces have gotten implanted ito *other* macro invocations. This is relevant
 597 // for macro hygiene, but possibly not elsewhere.
 598 //
 599 // One problem here occurs because the types for fold_item, fold_stmt, etc. allow the
 600 // folder to return *multiple* items; this is a problem for the nodes here, because
 601 // they insist on having exactly one piece. One solution would be to mangle the fold
 602 // trait to include one-to-many and one-to-one versions of these entry points, but that
 603 // would probably confuse a lot of people and help very few. Instead, I'm just going
 604 // to put in dynamic checks. I think the performance impact of this will be pretty much
 605 // nonexistent. The danger is that someone will apply a fold to a partially expanded
 606 // node, and will be confused by the fact that their "fold_item" or "fold_stmt" isn't
 607 // getting called on NtItem or NtStmt nodes. Hopefully they'll wind up reading this
 608 // comment, and doing something appropriate.
 609 //
 610 // BTW, design choice: I considered just changing the type of, e.g., NtItem to contain
 611 // multiple items, but decided against it when I looked at parse_item_or_view_item and
 612 // tried to figure out what I would do with multiple items there....
 613 pub fn noop_fold_interpolated<T: Folder>(nt: token::Nonterminal, fld: &mut T)
 614                                          -> token::Nonterminal {
 615     match nt {
 616         token::NtItem(item) =>
 617             token::NtItem(fld.fold_item(item)
 618                           // this is probably okay, because the only folds likely
 619                           // to peek inside interpolated nodes will be renamings/markings,
 620                           // which map single items to single items
 621                           .expect_one("expected fold to produce exactly one item")),
 622         token::NtBlock(block) => token::NtBlock(fld.fold_block(block)),
 623         token::NtStmt(stmt) =>
 624             token::NtStmt(fld.fold_stmt(stmt)
 625                           // this is probably okay, because the only folds likely
 626                           // to peek inside interpolated nodes will be renamings/markings,
 627                           // which map single items to single items
 628                           .expect_one("expected fold to produce exactly one statement")),
 629         token::NtPat(pat) => token::NtPat(fld.fold_pat(pat)),
 630         token::NtExpr(expr) => token::NtExpr(fld.fold_expr(expr)),
 631         token::NtTy(ty) => token::NtTy(fld.fold_ty(ty)),
 632         token::NtIdent(id) => token::NtIdent(Spanned::<Ident>{node: fld.fold_ident(id.node), ..id}),
 633         token::NtMeta(meta) => token::NtMeta(fld.fold_meta_item(meta)),
 634         token::NtPath(path) => token::NtPath(fld.fold_path(path)),
 635         token::NtTT(tt) => token::NtTT(fld.fold_tt(tt)),
 636         token::NtArm(arm) => token::NtArm(fld.fold_arm(arm)),
 637         token::NtImplItem(item) =>
 638             token::NtImplItem(fld.fold_impl_item(item)
 639                               .expect_one("expected fold to produce exactly one item")),
 640         token::NtTraitItem(item) =>
 641             token::NtTraitItem(fld.fold_trait_item(item)
 642                                .expect_one("expected fold to produce exactly one item")),
 643         token::NtGenerics(generics) => token::NtGenerics(fld.fold_generics(generics)),
 644         token::NtWhereClause(where_clause) =>
 645             token::NtWhereClause(fld.fold_where_clause(where_clause)),
 646         token::NtArg(arg) => token::NtArg(fld.fold_arg(arg)),
 647         token::NtVis(vis) => token::NtVis(fld.fold_vis(vis)),
 648         token::NtLifetime(lifetime) => token::NtLifetime(fld.fold_lifetime(lifetime)),
 649     }
 650 }
 651
 652 pub fn noop_fold_fn_decl<T: Folder>(decl: P<FnDecl>, fld: &mut T) -> P<FnDecl> {
 653     decl.map(|FnDecl {inputs, output, variadic}| FnDecl {
 654         inputs: inputs.move_map(|x| fld.fold_arg(x)),
 655         output: match output {
 656             FunctionRetTy::Ty(ty) => FunctionRetTy::Ty(fld.fold_ty(ty)),
 657             FunctionRetTy::Default(span) => FunctionRetTy::Default(fld.new_span(span)),
 658         },
 659         variadic,
 660     })
 661 }
 662
 663 pub fn noop_fold_ty_param_bound<T>(tpb: TyParamBound, fld: &mut T)
 664                                    -> TyParamBound
 665                                    where T: Folder {
 666     match tpb {
 667         TraitTyParamBound(ty, modifier) => TraitTyParamBound(fld.fold_poly_trait_ref(ty), modifier),
 668         RegionTyParamBound(lifetime) => RegionTyParamBound(fld.fold_lifetime(lifetime)),
 669     }
 670 }
 671
 672 pub fn noop_fold_ty_param<T: Folder>(tp: TyParam, fld: &mut T) -> TyParam {
 673     let TyParam {attrs, id, ident, bounds, default, span} = tp;
 674     let attrs: Vec<_> = attrs.into();
 675     TyParam {
 676         attrs: attrs.into_iter()
 677             .flat_map(|x| fld.fold_attribute(x).into_iter())
 678             .collect::<Vec<_>>()
 679             .into(),
 680         id: fld.new_id(id),
 681         ident: fld.fold_ident(ident),
 682         bounds: fld.fold_bounds(bounds),
 683         default: default.map(|x| fld.fold_ty(x)),
 684         span: fld.new_span(span),
 685     }
 686 }
 687
 688 pub fn noop_fold_generic_param<T: Folder>(param: GenericParam, fld: &mut T) -> GenericParam {
 689     match param {
 690         GenericParam::Lifetime(l) => GenericParam::Lifetime(fld.fold_lifetime_def(l)),
 691         GenericParam::Type(t) => GenericParam::Type(fld.fold_ty_param(t)),
 692     }
 693 }
 694
 695 pub fn noop_fold_generic_params<T: Folder>(
 696     params: Vec<GenericParam>,
 697     fld: &mut T
 698 ) -> Vec<GenericParam> {
 699     params.move_map(|p| fld.fold_generic_param(p))
 700 }
 701
 702 pub fn noop_fold_label<T: Folder>(label: Label, fld: &mut T) -> Label {
 703     Label {
 704         ident: fld.fold_ident(label.ident),
 705         span: fld.new_span(label.span),
 706     }
 707 }
 708
 709 pub fn noop_fold_lifetime<T: Folder>(l: Lifetime, fld: &mut T) -> Lifetime {
 710     Lifetime {
 711         id: fld.new_id(l.id),
 712         ident: fld.fold_ident(l.ident),
 713         span: fld.new_span(l.span)
 714     }
 715 }
 716
 717 pub fn noop_fold_lifetime_def<T: Folder>(l: LifetimeDef, fld: &mut T)
 718                                          -> LifetimeDef {
 719     let attrs: Vec<_> = l.attrs.into();
 720     LifetimeDef {
 721         attrs: attrs.into_iter()
 722             .flat_map(|x| fld.fold_attribute(x).into_iter())
 723             .collect::<Vec<_>>()
 724             .into(),
 725         lifetime: fld.fold_lifetime(l.lifetime),
 726         bounds: fld.fold_lifetimes(l.bounds),
 727     }
 728 }
 729
 730 pub fn noop_fold_lifetimes<T: Folder>(lts: Vec<Lifetime>, fld: &mut T) -> Vec<Lifetime> {
 731     lts.move_map(|l| fld.fold_lifetime(l))
 732 }
 733
 734 pub fn noop_fold_lifetime_defs<T: Folder>(lts: Vec<LifetimeDef>, fld: &mut T)
 735                                           -> Vec<LifetimeDef> {
 736     lts.move_map(|l| fld.fold_lifetime_def(l))
 737 }
 738
 739 pub fn noop_fold_opt_lifetime<T: Folder>(o_lt: Option<Lifetime>, fld: &mut T)
 740                                          -> Option<Lifetime> {
 741     o_lt.map(|lt| fld.fold_lifetime(lt))
 742 }
 743
 744 pub fn noop_fold_generics<T: Folder>(Generics { params, where_clause, span }: Generics,
 745                                      fld: &mut T) -> Generics {
 746     Generics {
 747         params: fld.fold_generic_params(params),
 748         where_clause: fld.fold_where_clause(where_clause),
 749         span: fld.new_span(span),
 750     }
 751 }
 752
 753 pub fn noop_fold_where_clause<T: Folder>(
 754                               WhereClause {id, predicates, span}: WhereClause,
 755                               fld: &mut T)
 756                               -> WhereClause {
 757     WhereClause {
 758         id: fld.new_id(id),
 759         predicates: predicates.move_map(|predicate| {
 760             fld.fold_where_predicate(predicate)
 761         }),
 762         span,
 763     }
 764 }
 765
 766 pub fn noop_fold_where_predicate<T: Folder>(
 767                                  pred: WherePredicate,
 768                                  fld: &mut T)
 769                                  -> WherePredicate {
 770     match pred {
 771         ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate{bound_generic_params,
 772                                                                      bounded_ty,
 773                                                                      bounds,
 774                                                                      span}) => {
 775             ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
 776                 bound_generic_params: fld.fold_generic_params(bound_generic_params),
 777                 bounded_ty: fld.fold_ty(bounded_ty),
 778                 bounds: bounds.move_map(|x| fld.fold_ty_param_bound(x)),
 779                 span: fld.new_span(span)
 780             })
 781         }
 782         ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate{lifetime,
 783                                                                        bounds,
 784                                                                        span}) => {
 785             ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
 786                 span: fld.new_span(span),
 787                 lifetime: fld.fold_lifetime(lifetime),
 788                 bounds: bounds.move_map(|bound| fld.fold_lifetime(bound))
 789             })
 790         }
 791         ast::WherePredicate::EqPredicate(ast::WhereEqPredicate{id,
 792                                                                lhs_ty,
 793                                                                rhs_ty,
 794                                                                span}) => {
 795             ast::WherePredicate::EqPredicate(ast::WhereEqPredicate{
 796                 id: fld.new_id(id),
 797                 lhs_ty: fld.fold_ty(lhs_ty),
 798                 rhs_ty: fld.fold_ty(rhs_ty),
 799                 span: fld.new_span(span)
 800             })
 801         }
 802     }
 803 }
 804
 805 pub fn noop_fold_variant_data<T: Folder>(vdata: VariantData, fld: &mut T) -> VariantData {
 806     match vdata {
 807         ast::VariantData::Struct(fields, id) => {
 808             ast::VariantData::Struct(fields.move_map(|f| fld.fold_struct_field(f)),
 809                                      fld.new_id(id))
 810         }
 811         ast::VariantData::Tuple(fields, id) => {
 812             ast::VariantData::Tuple(fields.move_map(|f| fld.fold_struct_field(f)),
 813                                     fld.new_id(id))
 814         }
 815         ast::VariantData::Unit(id) => ast::VariantData::Unit(fld.new_id(id))
 816     }
 817 }
 818
 819 pub fn noop_fold_trait_ref<T: Folder>(p: TraitRef, fld: &mut T) -> TraitRef {
 820     let id = fld.new_id(p.ref_id);
 821     let TraitRef {
 822         path,
 823         ref_id: _,
 824     } = p;
 825     ast::TraitRef {
 826         path: fld.fold_path(path),
 827         ref_id: id,
 828     }
 829 }
 830
 831 pub fn noop_fold_poly_trait_ref<T: Folder>(p: PolyTraitRef, fld: &mut T) -> PolyTraitRef {
 832     ast::PolyTraitRef {
 833         bound_generic_params: fld.fold_generic_params(p.bound_generic_params),
 834         trait_ref: fld.fold_trait_ref(p.trait_ref),
 835         span: fld.new_span(p.span),
 836     }
 837 }
 838
 839 pub fn noop_fold_struct_field<T: Folder>(f: StructField, fld: &mut T) -> StructField {
 840     StructField {
 841         span: fld.new_span(f.span),
 842         id: fld.new_id(f.id),
 843         ident: f.ident.map(|ident| fld.fold_ident(ident)),
 844         vis: fld.fold_vis(f.vis),
 845         ty: fld.fold_ty(f.ty),
 846         attrs: fold_attrs(f.attrs, fld),
 847     }
 848 }
 849
 850 pub fn noop_fold_field<T: Folder>(f: Field, folder: &mut T) -> Field {
 851     Field {
 852         ident: respan(f.ident.span, folder.fold_ident(f.ident.node)),
 853         expr: folder.fold_expr(f.expr),
 854         span: folder.new_span(f.span),
 855         is_shorthand: f.is_shorthand,
 856         attrs: fold_thin_attrs(f.attrs, folder),
 857     }
 858 }
 859
 860 pub fn noop_fold_mt<T: Folder>(MutTy {ty, mutbl}: MutTy, folder: &mut T) -> MutTy {
 861     MutTy {
 862         ty: folder.fold_ty(ty),
 863         mutbl,
 864     }
 865 }
 866
 867 pub fn noop_fold_opt_bounds<T: Folder>(b: Option<TyParamBounds>, folder: &mut T)
 868                                        -> Option<TyParamBounds> {
 869     b.map(|bounds| folder.fold_bounds(bounds))
 870 }
 871
 872 fn noop_fold_bounds<T: Folder>(bounds: TyParamBounds, folder: &mut T)
 873                           -> TyParamBounds {
 874     bounds.move_map(|bound| folder.fold_ty_param_bound(bound))
 875 }
 876
 877 pub fn noop_fold_block<T: Folder>(b: P<Block>, folder: &mut T) -> P<Block> {
 878     b.map(|Block {id, stmts, rules, span, recovered}| Block {
 879         id: folder.new_id(id),
 880         stmts: stmts.move_flat_map(|s| folder.fold_stmt(s).into_iter()),
 881         rules,
 882         span: folder.new_span(span),
 883         recovered,
 884     })
 885 }
 886
 887 pub fn noop_fold_item_kind<T: Folder>(i: ItemKind, folder: &mut T) -> ItemKind {
 888     match i {
 889         ItemKind::ExternCrate(string) => ItemKind::ExternCrate(string),
 890         ItemKind::Use(use_tree) => {
 891             ItemKind::Use(use_tree.map(|tree| folder.fold_use_tree(tree)))
 892         }
 893         ItemKind::Static(t, m, e) => {
 894             ItemKind::Static(folder.fold_ty(t), m, folder.fold_expr(e))
 895         }
 896         ItemKind::Const(t, e) => {
 897             ItemKind::Const(folder.fold_ty(t), folder.fold_expr(e))
 898         }
 899         ItemKind::Fn(decl, unsafety, constness, abi, generics, body) => {
 900             let generics = folder.fold_generics(generics);
 901             let decl = folder.fold_fn_decl(decl);
 902             let body = folder.fold_block(body);
 903             ItemKind::Fn(decl, unsafety, constness, abi, generics, body)
 904         }
 905         ItemKind::Mod(m) => ItemKind::Mod(folder.fold_mod(m)),
 906         ItemKind::ForeignMod(nm) => ItemKind::ForeignMod(folder.fold_foreign_mod(nm)),
 907         ItemKind::GlobalAsm(ga) => ItemKind::GlobalAsm(folder.fold_global_asm(ga)),
 908         ItemKind::Ty(t, generics) => {
 909             ItemKind::Ty(folder.fold_ty(t), folder.fold_generics(generics))
 910         }
 911         ItemKind::Enum(enum_definition, generics) => {
 912             let generics = folder.fold_generics(generics);
 913             let variants = enum_definition.variants.move_map(|x| folder.fold_variant(x));
 914             ItemKind::Enum(ast::EnumDef { variants: variants }, generics)
 915         }
 916         ItemKind::Struct(struct_def, generics) => {
 917             let generics = folder.fold_generics(generics);
 918             ItemKind::Struct(folder.fold_variant_data(struct_def), generics)
 919         }
 920         ItemKind::Union(struct_def, generics) => {
 921             let generics = folder.fold_generics(generics);
 922             ItemKind::Union(folder.fold_variant_data(struct_def), generics)
 923         }
 924         ItemKind::Impl(unsafety,
 925                        polarity,
 926                        defaultness,
 927                        generics,
 928                        ifce,
 929                        ty,
 930                        impl_items) => ItemKind::Impl(
 931             unsafety,
 932             polarity,
 933             defaultness,
 934             folder.fold_generics(generics),
 935             ifce.map(|trait_ref| folder.fold_trait_ref(trait_ref.clone())),
 936             folder.fold_ty(ty),
 937             impl_items.move_flat_map(|item| folder.fold_impl_item(item)),
 938         ),
 939         ItemKind::Trait(is_auto, unsafety, generics, bounds, items) => ItemKind::Trait(
 940             is_auto,
 941             unsafety,
 942             folder.fold_generics(generics),
 943             folder.fold_bounds(bounds),
 944             items.move_flat_map(|item| folder.fold_trait_item(item)),
 945         ),
 946         ItemKind::TraitAlias(generics, bounds) => ItemKind::TraitAlias(
 947             folder.fold_generics(generics),
 948             folder.fold_bounds(bounds)),
 949         ItemKind::Mac(m) => ItemKind::Mac(folder.fold_mac(m)),
 950         ItemKind::MacroDef(def) => ItemKind::MacroDef(folder.fold_macro_def(def)),
 951     }
 952 }
 953
 954 pub fn noop_fold_trait_item<T: Folder>(i: TraitItem, folder: &mut T)
 955                                        -> SmallVector<TraitItem> {
 956     SmallVector::one(TraitItem {
 957         id: folder.new_id(i.id),
 958         ident: folder.fold_ident(i.ident),
 959         attrs: fold_attrs(i.attrs, folder),
 960         generics: folder.fold_generics(i.generics),
 961         node: match i.node {
 962             TraitItemKind::Const(ty, default) => {
 963                 TraitItemKind::Const(folder.fold_ty(ty),
 964                                default.map(|x| folder.fold_expr(x)))
 965             }
 966             TraitItemKind::Method(sig, body) => {
 967                 TraitItemKind::Method(noop_fold_method_sig(sig, folder),
 968                                 body.map(|x| folder.fold_block(x)))
 969             }
 970             TraitItemKind::Type(bounds, default) => {
 971                 TraitItemKind::Type(folder.fold_bounds(bounds),
 972                               default.map(|x| folder.fold_ty(x)))
 973             }
 974             ast::TraitItemKind::Macro(mac) => {
 975                 TraitItemKind::Macro(folder.fold_mac(mac))
 976             }
 977         },
 978         span: folder.new_span(i.span),
 979         tokens: i.tokens,
 980     })
 981 }
 982
 983 pub fn noop_fold_impl_item<T: Folder>(i: ImplItem, folder: &mut T)
 984                                       -> SmallVector<ImplItem> {
 985     SmallVector::one(ImplItem {
 986         id: folder.new_id(i.id),
 987         vis: folder.fold_vis(i.vis),
 988         ident: folder.fold_ident(i.ident),
 989         attrs: fold_attrs(i.attrs, folder),
 990         generics: folder.fold_generics(i.generics),
 991         defaultness: i.defaultness,
 992         node: match i.node  {
 993             ast::ImplItemKind::Const(ty, expr) => {
 994                 ast::ImplItemKind::Const(folder.fold_ty(ty), folder.fold_expr(expr))
 995             }
 996             ast::ImplItemKind::Method(sig, body) => {
 997                 ast::ImplItemKind::Method(noop_fold_method_sig(sig, folder),
 998                                folder.fold_block(body))
 999             }
1000             ast::ImplItemKind::Type(ty) => ast::ImplItemKind::Type(folder.fold_ty(ty)),
1001             ast::ImplItemKind::Macro(mac) => ast::ImplItemKind::Macro(folder.fold_mac(mac))
1002         },
1003         span: folder.new_span(i.span),
1004         tokens: i.tokens,
1005     })
1006 }
1007
1008 pub fn noop_fold_mod<T: Folder>(Mod {inner, items}: Mod, folder: &mut T) -> Mod {
1009     Mod {
1010         inner: folder.new_span(inner),
1011         items: items.move_flat_map(|x| folder.fold_item(x)),
1012     }
1013 }
1014
1015 pub fn noop_fold_crate<T: Folder>(Crate {module, attrs, span}: Crate,
1016                                   folder: &mut T) -> Crate {
1017     let mut items = folder.fold_item(P(ast::Item {
1018         ident: keywords::Invalid.ident(),
1019         attrs,
1020         id: ast::DUMMY_NODE_ID,
1021         vis: ast::Visibility::Public,
1022         span,
1023         node: ast::ItemKind::Mod(module),
1024         tokens: None,
1025     })).into_iter();
1026
1027     let (module, attrs, span) = match items.next() {
1028         Some(item) => {
1029             assert!(items.next().is_none(),
1030                     "a crate cannot expand to more than one item");
1031             item.and_then(|ast::Item { attrs, span, node, .. }| {
1032                 match node {
1033                     ast::ItemKind::Mod(m) => (m, attrs, span),
1034                     _ => panic!("fold converted a module to not a module"),
1035                 }
1036             })
1037         }
1038         None => (ast::Mod {
1039             inner: span,
1040             items: vec![],
1041         }, vec![], span)
1042     };
1043
1044     Crate {
1045         module,
1046         attrs,
1047         span,
1048     }
1049 }
1050
1051 // fold one item into possibly many items
1052 pub fn noop_fold_item<T: Folder>(i: P<Item>, folder: &mut T) -> SmallVector<P<Item>> {
1053     SmallVector::one(i.map(|i| folder.fold_item_simple(i)))
1054 }
1055
1056 // fold one item into exactly one item
1057 pub fn noop_fold_item_simple<T: Folder>(Item {id, ident, attrs, node, vis, span, tokens}: Item,
1058                                         folder: &mut T) -> Item {
1059     Item {
1060         id: folder.new_id(id),
1061         vis: folder.fold_vis(vis),
1062         ident: folder.fold_ident(ident),
1063         attrs: fold_attrs(attrs, folder),
1064         node: folder.fold_item_kind(node),
1065         span: folder.new_span(span),
1066
1067         // FIXME: if this is replaced with a call to `folder.fold_tts` it causes
1068         //        an ICE during resolve... odd!
1069         tokens,
1070     }
1071 }
1072
1073 pub fn noop_fold_foreign_item<T: Folder>(ni: ForeignItem, folder: &mut T) -> ForeignItem {
1074     ForeignItem {
1075         id: folder.new_id(ni.id),
1076         vis: folder.fold_vis(ni.vis),
1077         ident: folder.fold_ident(ni.ident),
1078         attrs: fold_attrs(ni.attrs, folder),
1079         node: match ni.node {
1080             ForeignItemKind::Fn(fdec, generics) => {
1081                 ForeignItemKind::Fn(folder.fold_fn_decl(fdec), folder.fold_generics(generics))
1082             }
1083             ForeignItemKind::Static(t, m) => {
1084                 ForeignItemKind::Static(folder.fold_ty(t), m)
1085             }
1086             ForeignItemKind::Ty => ForeignItemKind::Ty,
1087         },
1088         span: folder.new_span(ni.span)
1089     }
1090 }
1091
1092 pub fn noop_fold_method_sig<T: Folder>(sig: MethodSig, folder: &mut T) -> MethodSig {
1093     MethodSig {
1094         abi: sig.abi,
1095         unsafety: sig.unsafety,
1096         constness: sig.constness,
1097         decl: folder.fold_fn_decl(sig.decl)
1098     }
1099 }
1100
1101 pub fn noop_fold_pat<T: Folder>(p: P<Pat>, folder: &mut T) -> P<Pat> {
1102     p.map(|Pat {id, node, span}| Pat {
1103         id: folder.new_id(id),
1104         node: match node {
1105             PatKind::Wild => PatKind::Wild,
1106             PatKind::Ident(binding_mode, pth1, sub) => {
1107                 PatKind::Ident(binding_mode,
1108                         Spanned{span: folder.new_span(pth1.span),
1109                                 node: folder.fold_ident(pth1.node)},
1110                         sub.map(|x| folder.fold_pat(x)))
1111             }
1112             PatKind::Lit(e) => PatKind::Lit(folder.fold_expr(e)),
1113             PatKind::TupleStruct(pth, pats, ddpos) => {
1114                 PatKind::TupleStruct(folder.fold_path(pth),
1115                         pats.move_map(|x| folder.fold_pat(x)), ddpos)
1116             }
1117             PatKind::Path(opt_qself, pth) => {
1118                 let opt_qself = opt_qself.map(|qself| {
1119                     QSelf { ty: folder.fold_ty(qself.ty), position: qself.position }
1120                 });
1121                 PatKind::Path(opt_qself, folder.fold_path(pth))
1122             }
1123             PatKind::Struct(pth, fields, etc) => {
1124                 let pth = folder.fold_path(pth);
1125                 let fs = fields.move_map(|f| {
1126                     Spanned { span: folder.new_span(f.span),
1127                               node: ast::FieldPat {
1128                                   ident: folder.fold_ident(f.node.ident),
1129                                   pat: folder.fold_pat(f.node.pat),
1130                                   is_shorthand: f.node.is_shorthand,
1131                                   attrs: fold_attrs(f.node.attrs.into(), folder).into()
1132                               }}
1133                 });
1134                 PatKind::Struct(pth, fs, etc)
1135             }
1136             PatKind::Tuple(elts, ddpos) => {
1137                 PatKind::Tuple(elts.move_map(|x| folder.fold_pat(x)), ddpos)
1138             }
1139             PatKind::Box(inner) => PatKind::Box(folder.fold_pat(inner)),
1140             PatKind::Ref(inner, mutbl) => PatKind::Ref(folder.fold_pat(inner), mutbl),
1141             PatKind::Range(e1, e2, end) => {
1142                 PatKind::Range(folder.fold_expr(e1),
1143                                folder.fold_expr(e2),
1144                                folder.fold_range_end(end))
1145             },
1146             PatKind::Slice(before, slice, after) => {
1147                 PatKind::Slice(before.move_map(|x| folder.fold_pat(x)),
1148                        slice.map(|x| folder.fold_pat(x)),
1149                        after.move_map(|x| folder.fold_pat(x)))
1150             }
1151             PatKind::Mac(mac) => PatKind::Mac(folder.fold_mac(mac))
1152         },
1153         span: folder.new_span(span)
1154     })
1155 }
1156
1157 pub fn noop_fold_range_end<T: Folder>(end: RangeEnd, _folder: &mut T) -> RangeEnd {
1158     end
1159 }
1160
1161 pub fn noop_fold_expr<T: Folder>(Expr {id, node, span, attrs}: Expr, folder: &mut T) -> Expr {
1162     Expr {
1163         node: match node {
1164             ExprKind::Box(e) => {
1165                 ExprKind::Box(folder.fold_expr(e))
1166             }
1167             ExprKind::InPlace(p, e) => {
1168                 ExprKind::InPlace(folder.fold_expr(p), folder.fold_expr(e))
1169             }
1170             ExprKind::Array(exprs) => {
1171                 ExprKind::Array(folder.fold_exprs(exprs))
1172             }
1173             ExprKind::Repeat(expr, count) => {
1174                 ExprKind::Repeat(folder.fold_expr(expr), folder.fold_expr(count))
1175             }
1176             ExprKind::Tup(exprs) => ExprKind::Tup(folder.fold_exprs(exprs)),
1177             ExprKind::Call(f, args) => {
1178                 ExprKind::Call(folder.fold_expr(f),
1179                          folder.fold_exprs(args))
1180             }
1181             ExprKind::MethodCall(seg, args) => {
1182                 ExprKind::MethodCall(
1183                     PathSegment {
1184                         identifier: folder.fold_ident(seg.identifier),
1185                         span: folder.new_span(seg.span),
1186                         parameters: seg.parameters.map(|ps| {
1187                             ps.map(|ps| folder.fold_path_parameters(ps))
1188                         }),
1189                     },
1190                     folder.fold_exprs(args))
1191             }
1192             ExprKind::Binary(binop, lhs, rhs) => {
1193                 ExprKind::Binary(binop,
1194                         folder.fold_expr(lhs),
1195                         folder.fold_expr(rhs))
1196             }
1197             ExprKind::Unary(binop, ohs) => {
1198                 ExprKind::Unary(binop, folder.fold_expr(ohs))
1199             }
1200             ExprKind::Lit(l) => ExprKind::Lit(l),
1201             ExprKind::Cast(expr, ty) => {
1202                 ExprKind::Cast(folder.fold_expr(expr), folder.fold_ty(ty))
1203             }
1204             ExprKind::Type(expr, ty) => {
1205                 ExprKind::Type(folder.fold_expr(expr), folder.fold_ty(ty))
1206             }
1207             ExprKind::AddrOf(m, ohs) => ExprKind::AddrOf(m, folder.fold_expr(ohs)),
1208             ExprKind::If(cond, tr, fl) => {
1209                 ExprKind::If(folder.fold_expr(cond),
1210                        folder.fold_block(tr),
1211                        fl.map(|x| folder.fold_expr(x)))
1212             }
1213             ExprKind::IfLet(pat, expr, tr, fl) => {
1214                 ExprKind::IfLet(folder.fold_pat(pat),
1215                           folder.fold_expr(expr),
1216                           folder.fold_block(tr),
1217                           fl.map(|x| folder.fold_expr(x)))
1218             }
1219             ExprKind::While(cond, body, opt_label) => {
1220                 ExprKind::While(folder.fold_expr(cond),
1221                           folder.fold_block(body),
1222                           opt_label.map(|label| folder.fold_label(label)))
1223             }
1224             ExprKind::WhileLet(pat, expr, body, opt_label) => {
1225                 ExprKind::WhileLet(folder.fold_pat(pat),
1226                              folder.fold_expr(expr),
1227                              folder.fold_block(body),
1228                              opt_label.map(|label| folder.fold_label(label)))
1229             }
1230             ExprKind::ForLoop(pat, iter, body, opt_label) => {
1231                 ExprKind::ForLoop(folder.fold_pat(pat),
1232                             folder.fold_expr(iter),
1233                             folder.fold_block(body),
1234                             opt_label.map(|label| folder.fold_label(label)))
1235             }
1236             ExprKind::Loop(body, opt_label) => {
1237                 ExprKind::Loop(folder.fold_block(body),
1238                                opt_label.map(|label| folder.fold_label(label)))
1239             }
1240             ExprKind::Match(expr, arms) => {
1241                 ExprKind::Match(folder.fold_expr(expr),
1242                           arms.move_map(|x| folder.fold_arm(x)))
1243             }
1244             ExprKind::Closure(capture_clause, movability, decl, body, span) => {
1245                 ExprKind::Closure(capture_clause,
1246                                   movability,
1247                                   folder.fold_fn_decl(decl),
1248                                   folder.fold_expr(body),
1249                                   folder.new_span(span))
1250             }
1251             ExprKind::Block(blk) => ExprKind::Block(folder.fold_block(blk)),
1252             ExprKind::Assign(el, er) => {
1253                 ExprKind::Assign(folder.fold_expr(el), folder.fold_expr(er))
1254             }
1255             ExprKind::AssignOp(op, el, er) => {
1256                 ExprKind::AssignOp(op,
1257                             folder.fold_expr(el),
1258                             folder.fold_expr(er))
1259             }
1260             ExprKind::Field(el, ident) => {
1261                 ExprKind::Field(folder.fold_expr(el),
1262                           respan(folder.new_span(ident.span),
1263                                  folder.fold_ident(ident.node)))
1264             }
1265             ExprKind::TupField(el, ident) => {
1266                 ExprKind::TupField(folder.fold_expr(el),
1267                              respan(folder.new_span(ident.span),
1268                                     folder.fold_usize(ident.node)))
1269             }
1270             ExprKind::Index(el, er) => {
1271                 ExprKind::Index(folder.fold_expr(el), folder.fold_expr(er))
1272             }
1273             ExprKind::Range(e1, e2, lim) => {
1274                 ExprKind::Range(e1.map(|x| folder.fold_expr(x)),
1275                                 e2.map(|x| folder.fold_expr(x)),
1276                                 lim)
1277             }
1278             ExprKind::Path(qself, path) => {
1279                 let qself = qself.map(|QSelf { ty, position }| {
1280                     QSelf {
1281                         ty: folder.fold_ty(ty),
1282                         position,
1283                     }
1284                 });
1285                 ExprKind::Path(qself, folder.fold_path(path))
1286             }
1287             ExprKind::Break(opt_label, opt_expr) => {
1288                 ExprKind::Break(opt_label.map(|label| folder.fold_label(label)),
1289                                 opt_expr.map(|e| folder.fold_expr(e)))
1290             }
1291             ExprKind::Continue(opt_label) => {
1292                 ExprKind::Continue(opt_label.map(|label| folder.fold_label(label)))
1293             }
1294             ExprKind::Ret(e) => ExprKind::Ret(e.map(|x| folder.fold_expr(x))),
1295             ExprKind::InlineAsm(asm) => ExprKind::InlineAsm(asm.map(|asm| {
1296                 InlineAsm {
1297                     inputs: asm.inputs.move_map(|(c, input)| {
1298                         (c, folder.fold_expr(input))
1299                     }),
1300                     outputs: asm.outputs.move_map(|out| {
1301                         InlineAsmOutput {
1302                             constraint: out.constraint,
1303                             expr: folder.fold_expr(out.expr),
1304                             is_rw: out.is_rw,
1305                             is_indirect: out.is_indirect,
1306                         }
1307                     }),
1308                     ..asm
1309                 }
1310             })),
1311             ExprKind::Mac(mac) => ExprKind::Mac(folder.fold_mac(mac)),
1312             ExprKind::Struct(path, fields, maybe_expr) => {
1313                 ExprKind::Struct(folder.fold_path(path),
1314                         fields.move_map(|x| folder.fold_field(x)),
1315                         maybe_expr.map(|x| folder.fold_expr(x)))
1316             },
1317             ExprKind::Paren(ex) => {
1318                 let sub_expr = folder.fold_expr(ex);
1319                 return Expr {
1320                     // Nodes that are equal modulo `Paren` sugar no-ops should have the same ids.
1321                     id: sub_expr.id,
1322                     node: ExprKind::Paren(sub_expr),
1323                     span: folder.new_span(span),
1324                     attrs: fold_attrs(attrs.into(), folder).into(),
1325                 };
1326             }
1327             ExprKind::Yield(ex) => ExprKind::Yield(ex.map(|x| folder.fold_expr(x))),
1328             ExprKind::Try(ex) => ExprKind::Try(folder.fold_expr(ex)),
1329             ExprKind::Catch(body) => ExprKind::Catch(folder.fold_block(body)),
1330         },
1331         id: folder.new_id(id),
1332         span: folder.new_span(span),
1333         attrs: fold_attrs(attrs.into(), folder).into(),
1334     }
1335 }
1336
1337 pub fn noop_fold_opt_expr<T: Folder>(e: P<Expr>, folder: &mut T) -> Option<P<Expr>> {
1338     Some(folder.fold_expr(e))
1339 }
1340
1341 pub fn noop_fold_exprs<T: Folder>(es: Vec<P<Expr>>, folder: &mut T) -> Vec<P<Expr>> {
1342     es.move_flat_map(|e| folder.fold_opt_expr(e))
1343 }
1344
1345 pub fn noop_fold_stmt<T: Folder>(Stmt {node, span, id}: Stmt, folder: &mut T) -> SmallVector<Stmt> {
1346     let id = folder.new_id(id);
1347     let span = folder.new_span(span);
1348     noop_fold_stmt_kind(node, folder).into_iter().map(|node| {
1349         Stmt { id: id, node: node, span: span }
1350     }).collect()
1351 }
1352
1353 pub fn noop_fold_stmt_kind<T: Folder>(node: StmtKind, folder: &mut T) -> SmallVector<StmtKind> {
1354     match node {
1355         StmtKind::Local(local) => SmallVector::one(StmtKind::Local(folder.fold_local(local))),
1356         StmtKind::Item(item) => folder.fold_item(item).into_iter().map(StmtKind::Item).collect(),
1357         StmtKind::Expr(expr) => {
1358             folder.fold_opt_expr(expr).into_iter().map(StmtKind::Expr).collect()
1359         }
1360         StmtKind::Semi(expr) => {
1361             folder.fold_opt_expr(expr).into_iter().map(StmtKind::Semi).collect()
1362         }
1363         StmtKind::Mac(mac) => SmallVector::one(StmtKind::Mac(mac.map(|(mac, semi, attrs)| {
1364             (folder.fold_mac(mac), semi, fold_attrs(attrs.into(), folder).into())
1365         }))),
1366     }
1367 }
1368
1369 pub fn noop_fold_vis<T: Folder>(vis: Visibility, folder: &mut T) -> Visibility {
1370     match vis {
1371         Visibility::Restricted { path, id } => Visibility::Restricted {
1372             path: path.map(|path| folder.fold_path(path)),
1373             id: folder.new_id(id)
1374         },
1375         _ => vis,
1376     }
1377 }
1378
1379 #[cfg(test)]
1380 mod tests {
1381     use std::io;
1382     use ast::{self, Ident};
1383     use util::parser_testing::{string_to_crate, matches_codepattern};
1384     use print::pprust;
1385     use fold;
1386     use super::*;
1387
1388     // this version doesn't care about getting comments or docstrings in.
1389     fn fake_print_crate(s: &mut pprust::State,
1390                         krate: &ast::Crate) -> io::Result<()> {
1391         s.print_mod(&krate.module, &krate.attrs)
1392     }
1393
1394     // change every identifier to "zz"
1395     struct ToZzIdentFolder;
1396
1397     impl Folder for ToZzIdentFolder {
1398         fn fold_ident(&mut self, _: ast::Ident) -> ast::Ident {
1399             Ident::from_str("zz")
1400         }
1401         fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
1402             fold::noop_fold_mac(mac, self)
1403         }
1404     }
1405
1406     // maybe add to expand.rs...
1407     macro_rules! assert_pred {
1408         ($pred:expr, $predname:expr, $a:expr , $b:expr) => (
1409             {
1410                 let pred_val = $pred;
1411                 let a_val = $a;
1412                 let b_val = $b;
1413                 if !(pred_val(&a_val, &b_val)) {
1414                     panic!("expected args satisfying {}, got {} and {}",
1415                           $predname, a_val, b_val);
1416                 }
1417             }
1418         )
1419     }
1420
1421     // make sure idents get transformed everywhere
1422     #[test] fn ident_transformation () {
1423         let mut zz_fold = ToZzIdentFolder;
1424         let ast = string_to_crate(
1425             "#[a] mod b {fn c (d : e, f : g) {h!(i,j,k);l;m}}".to_string());
1426         let folded_crate = zz_fold.fold_crate(ast);
1427         assert_pred!(
1428             matches_codepattern,
1429             "matches_codepattern",
1430             pprust::to_string(|s| fake_print_crate(s, &folded_crate)),
1431             "#[zz]mod zz{fn zz(zz:zz,zz:zz){zz!(zz,zz,zz);zz;zz}}".to_string());
1432     }
1433
1434     // even inside macro defs....
1435     #[test] fn ident_transformation_in_defs () {
1436         let mut zz_fold = ToZzIdentFolder;
1437         let ast = string_to_crate(
1438             "macro_rules! a {(b $c:expr $(d $e:token)f+ => \
1439              (g $(d $d $e)+))} ".to_string());
1440         let folded_crate = zz_fold.fold_crate(ast);
1441         assert_pred!(
1442             matches_codepattern,
1443             "matches_codepattern",
1444             pprust::to_string(|s| fake_print_crate(s, &folded_crate)),
1445             "macro_rules! zz((zz$zz:zz$(zz $zz:zz)zz+=>(zz$(zz$zz$zz)+)));".to_string());
1446     }
1447 }