src/libsyntax/ext/build.rs

   1 // Copyright 2012 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 use abi;
  12 use ast::{P, Ident, Generics, NodeId, Expr};
  13 use ast;
  14 use ast_util;
  15 use attr;
  16 use codemap::{Span, respan, Spanned, DUMMY_SP, Pos};
  17 use ext::base::ExtCtxt;
  18 use fold::Folder;
  19 use owned_slice::OwnedSlice;
  20 use parse::token::special_idents;
  21 use parse::token::InternedString;
  22 use parse::token;
  23
  24 use std::gc::{Gc, GC};
  25
  26 // Transitional reexports so qquote can find the paths it is looking for
  27 mod syntax {
  28     pub use ext;
  29     pub use parse;
  30 }
  31
  32 pub trait AstBuilder {
  33     // paths
  34     fn path(&self, span: Span, strs: Vec<ast::Ident> ) -> ast::Path;
  35     fn path_ident(&self, span: Span, id: ast::Ident) -> ast::Path;
  36     fn path_global(&self, span: Span, strs: Vec<ast::Ident> ) -> ast::Path;
  37     fn path_all(&self, sp: Span,
  38                 global: bool,
  39                 idents: Vec<ast::Ident> ,
  40                 lifetimes: Vec<ast::Lifetime>,
  41                 types: Vec<P<ast::Ty>> )
  42         -> ast::Path;
  43
  44     // types
  45     fn ty_mt(&self, ty: P<ast::Ty>, mutbl: ast::Mutability) -> ast::MutTy;
  46
  47     fn ty(&self, span: Span, ty: ast::Ty_) -> P<ast::Ty>;
  48     fn ty_path(&self, ast::Path, Option<OwnedSlice<ast::TyParamBound>>) -> P<ast::Ty>;
  49     fn ty_ident(&self, span: Span, idents: ast::Ident) -> P<ast::Ty>;
  50
  51     fn ty_rptr(&self, span: Span,
  52                ty: P<ast::Ty>,
  53                lifetime: Option<ast::Lifetime>,
  54                mutbl: ast::Mutability) -> P<ast::Ty>;
  55     fn ty_uniq(&self, span: Span, ty: P<ast::Ty>) -> P<ast::Ty>;
  56
  57     fn ty_option(&self, ty: P<ast::Ty>) -> P<ast::Ty>;
  58     fn ty_infer(&self, sp: Span) -> P<ast::Ty>;
  59     fn ty_nil(&self) -> P<ast::Ty>;
  60
  61     fn ty_vars(&self, ty_params: &OwnedSlice<ast::TyParam>) -> Vec<P<ast::Ty>> ;
  62     fn ty_vars_global(&self, ty_params: &OwnedSlice<ast::TyParam>) -> Vec<P<ast::Ty>> ;
  63     fn ty_field_imm(&self, span: Span, name: Ident, ty: P<ast::Ty>) -> ast::TypeField;
  64     fn strip_bounds(&self, bounds: &Generics) -> Generics;
  65
  66     fn typaram(&self,
  67                span: Span,
  68                id: ast::Ident,
  69                bounds: OwnedSlice<ast::TyParamBound>,
  70                unbound: Option<ast::TyParamBound>,
  71                default: Option<P<ast::Ty>>) -> ast::TyParam;
  72
  73     fn trait_ref(&self, path: ast::Path) -> ast::TraitRef;
  74     fn typarambound(&self, path: ast::Path) -> ast::TyParamBound;
  75     fn lifetime(&self, span: Span, ident: ast::Name) -> ast::Lifetime;
  76
  77     // statements
  78     fn stmt_expr(&self, expr: Gc<ast::Expr>) -> Gc<ast::Stmt>;
  79     fn stmt_let(&self, sp: Span, mutbl: bool, ident: ast::Ident,
  80                 ex: Gc<ast::Expr>) -> Gc<ast::Stmt>;
  81     fn stmt_let_typed(&self,
  82                       sp: Span,
  83                       mutbl: bool,
  84                       ident: ast::Ident,
  85                       typ: P<ast::Ty>,
  86                       ex: Gc<ast::Expr>)
  87                       -> Gc<ast::Stmt>;
  88     fn stmt_item(&self, sp: Span, item: Gc<ast::Item>) -> Gc<ast::Stmt>;
  89
  90     // blocks
  91     fn block(&self, span: Span, stmts: Vec<Gc<ast::Stmt>>,
  92              expr: Option<Gc<ast::Expr>>) -> P<ast::Block>;
  93     fn block_expr(&self, expr: Gc<ast::Expr>) -> P<ast::Block>;
  94     fn block_all(&self, span: Span,
  95                  view_items: Vec<ast::ViewItem> ,
  96                  stmts: Vec<Gc<ast::Stmt>> ,
  97                  expr: Option<Gc<ast::Expr>>) -> P<ast::Block>;
  98
  99     // expressions
 100     fn expr(&self, span: Span, node: ast::Expr_) -> Gc<ast::Expr>;
 101     fn expr_path(&self, path: ast::Path) -> Gc<ast::Expr>;
 102     fn expr_ident(&self, span: Span, id: ast::Ident) -> Gc<ast::Expr>;
 103
 104     fn expr_self(&self, span: Span) -> Gc<ast::Expr>;
 105     fn expr_binary(&self, sp: Span, op: ast::BinOp,
 106                    lhs: Gc<ast::Expr>, rhs: Gc<ast::Expr>) -> Gc<ast::Expr>;
 107     fn expr_deref(&self, sp: Span, e: Gc<ast::Expr>) -> Gc<ast::Expr>;
 108     fn expr_unary(&self, sp: Span, op: ast::UnOp, e: Gc<ast::Expr>) -> Gc<ast::Expr>;
 109
 110     fn expr_managed(&self, sp: Span, e: Gc<ast::Expr>) -> Gc<ast::Expr>;
 111     fn expr_addr_of(&self, sp: Span, e: Gc<ast::Expr>) -> Gc<ast::Expr>;
 112     fn expr_mut_addr_of(&self, sp: Span, e: Gc<ast::Expr>) -> Gc<ast::Expr>;
 113     fn expr_field_access(&self, span: Span, expr: Gc<ast::Expr>,
 114                          ident: ast::Ident) -> Gc<ast::Expr>;
 115     fn expr_call(&self, span: Span, expr: Gc<ast::Expr>,
 116                  args: Vec<Gc<ast::Expr>>) -> Gc<ast::Expr>;
 117     fn expr_call_ident(&self, span: Span, id: ast::Ident,
 118                        args: Vec<Gc<ast::Expr>>) -> Gc<ast::Expr>;
 119     fn expr_call_global(&self, sp: Span, fn_path: Vec<ast::Ident> ,
 120                         args: Vec<Gc<ast::Expr>>) -> Gc<ast::Expr>;
 121     fn expr_method_call(&self, span: Span,
 122                         expr: Gc<ast::Expr>, ident: ast::Ident,
 123                         args: Vec<Gc<ast::Expr>> ) -> Gc<ast::Expr>;
 124     fn expr_block(&self, b: P<ast::Block>) -> Gc<ast::Expr>;
 125     fn expr_cast(&self, sp: Span, expr: Gc<ast::Expr>,
 126                  ty: P<ast::Ty>) -> Gc<ast::Expr>;
 127
 128     fn field_imm(&self, span: Span, name: Ident, e: Gc<ast::Expr>) -> ast::Field;
 129     fn expr_struct(&self, span: Span, path: ast::Path,
 130                    fields: Vec<ast::Field> ) -> Gc<ast::Expr>;
 131     fn expr_struct_ident(&self, span: Span, id: ast::Ident,
 132                          fields: Vec<ast::Field> ) -> Gc<ast::Expr>;
 133
 134     fn expr_lit(&self, sp: Span, lit: ast::Lit_) -> Gc<ast::Expr>;
 135
 136     fn expr_uint(&self, span: Span, i: uint) -> Gc<ast::Expr>;
 137     fn expr_int(&self, sp: Span, i: int) -> Gc<ast::Expr>;
 138     fn expr_u8(&self, sp: Span, u: u8) -> Gc<ast::Expr>;
 139     fn expr_bool(&self, sp: Span, value: bool) -> Gc<ast::Expr>;
 140
 141     fn expr_vstore(&self, sp: Span, expr: Gc<ast::Expr>, vst: ast::ExprVstore) -> Gc<ast::Expr>;
 142     fn expr_vec(&self, sp: Span, exprs: Vec<Gc<ast::Expr>> ) -> Gc<ast::Expr>;
 143     fn expr_vec_ng(&self, sp: Span) -> Gc<ast::Expr>;
 144     fn expr_vec_slice(&self, sp: Span, exprs: Vec<Gc<ast::Expr>> ) -> Gc<ast::Expr>;
 145     fn expr_str(&self, sp: Span, s: InternedString) -> Gc<ast::Expr>;
 146     fn expr_str_uniq(&self, sp: Span, s: InternedString) -> Gc<ast::Expr>;
 147
 148     fn expr_some(&self, sp: Span, expr: Gc<ast::Expr>) -> Gc<ast::Expr>;
 149     fn expr_none(&self, sp: Span) -> Gc<ast::Expr>;
 150
 151     fn expr_tuple(&self, sp: Span, exprs: Vec<Gc<ast::Expr>>) -> Gc<ast::Expr>;
 152
 153     fn expr_fail(&self, span: Span, msg: InternedString) -> Gc<ast::Expr>;
 154     fn expr_unreachable(&self, span: Span) -> Gc<ast::Expr>;
 155
 156     fn expr_ok(&self, span: Span, expr: Gc<ast::Expr>) -> Gc<ast::Expr>;
 157     fn expr_err(&self, span: Span, expr: Gc<ast::Expr>) -> Gc<ast::Expr>;
 158     fn expr_try(&self, span: Span, head: Gc<ast::Expr>) -> Gc<ast::Expr>;
 159
 160     fn pat(&self, span: Span, pat: ast::Pat_) -> Gc<ast::Pat>;
 161     fn pat_wild(&self, span: Span) -> Gc<ast::Pat>;
 162     fn pat_lit(&self, span: Span, expr: Gc<ast::Expr>) -> Gc<ast::Pat>;
 163     fn pat_ident(&self, span: Span, ident: ast::Ident) -> Gc<ast::Pat>;
 164
 165     fn pat_ident_binding_mode(&self,
 166                               span: Span,
 167                               ident: ast::Ident,
 168                               bm: ast::BindingMode) -> Gc<ast::Pat>;
 169     fn pat_enum(&self, span: Span, path: ast::Path,
 170                 subpats: Vec<Gc<ast::Pat>>) -> Gc<ast::Pat>;
 171     fn pat_struct(&self, span: Span,
 172                   path: ast::Path, field_pats: Vec<ast::FieldPat> ) -> Gc<ast::Pat>;
 173
 174     fn arm(&self, span: Span, pats: Vec<Gc<ast::Pat>> , expr: Gc<ast::Expr>) -> ast::Arm;
 175     fn arm_unreachable(&self, span: Span) -> ast::Arm;
 176
 177     fn expr_match(&self, span: Span, arg: Gc<ast::Expr>, arms: Vec<ast::Arm> ) -> Gc<ast::Expr>;
 178     fn expr_if(&self, span: Span,
 179                cond: Gc<ast::Expr>, then: Gc<ast::Expr>,
 180                els: Option<Gc<ast::Expr>>) -> Gc<ast::Expr>;
 181
 182     fn lambda_fn_decl(&self, span: Span,
 183                       fn_decl: P<ast::FnDecl>, blk: P<ast::Block>) -> Gc<ast::Expr>;
 184
 185     fn lambda(&self, span: Span, ids: Vec<ast::Ident> , blk: P<ast::Block>) -> Gc<ast::Expr>;
 186     fn lambda0(&self, span: Span, blk: P<ast::Block>) -> Gc<ast::Expr>;
 187     fn lambda1(&self, span: Span, blk: P<ast::Block>, ident: ast::Ident) -> Gc<ast::Expr>;
 188
 189     fn lambda_expr(&self, span: Span, ids: Vec<ast::Ident> , blk: Gc<ast::Expr>) -> Gc<ast::Expr>;
 190     fn lambda_expr_0(&self, span: Span, expr: Gc<ast::Expr>) -> Gc<ast::Expr>;
 191     fn lambda_expr_1(&self, span: Span, expr: Gc<ast::Expr>, ident: ast::Ident) -> Gc<ast::Expr>;
 192
 193     fn lambda_stmts(&self, span: Span, ids: Vec<ast::Ident>,
 194                     blk: Vec<Gc<ast::Stmt>>) -> Gc<ast::Expr>;
 195     fn lambda_stmts_0(&self, span: Span,
 196                       stmts: Vec<Gc<ast::Stmt>>) -> Gc<ast::Expr>;
 197     fn lambda_stmts_1(&self, span: Span,
 198                       stmts: Vec<Gc<ast::Stmt>>, ident: ast::Ident) -> Gc<ast::Expr>;
 199
 200     // items
 201     fn item(&self, span: Span,
 202             name: Ident, attrs: Vec<ast::Attribute>,
 203             node: ast::Item_) -> Gc<ast::Item>;
 204
 205     fn arg(&self, span: Span, name: Ident, ty: P<ast::Ty>) -> ast::Arg;
 206     // FIXME unused self
 207     fn fn_decl(&self, inputs: Vec<ast::Arg> , output: P<ast::Ty>) -> P<ast::FnDecl>;
 208
 209     fn item_fn_poly(&self,
 210                     span: Span,
 211                     name: Ident,
 212                     inputs: Vec<ast::Arg> ,
 213                     output: P<ast::Ty>,
 214                     generics: Generics,
 215                     body: P<ast::Block>) -> Gc<ast::Item>;
 216     fn item_fn(&self,
 217                span: Span,
 218                name: Ident,
 219                inputs: Vec<ast::Arg> ,
 220                output: P<ast::Ty>,
 221                body: P<ast::Block>) -> Gc<ast::Item>;
 222
 223     fn variant(&self, span: Span, name: Ident, tys: Vec<P<ast::Ty>> ) -> ast::Variant;
 224     fn item_enum_poly(&self,
 225                       span: Span,
 226                       name: Ident,
 227                       enum_definition: ast::EnumDef,
 228                       generics: Generics) -> Gc<ast::Item>;
 229     fn item_enum(&self, span: Span, name: Ident,
 230                  enum_def: ast::EnumDef) -> Gc<ast::Item>;
 231
 232     fn item_struct_poly(&self,
 233                         span: Span,
 234                         name: Ident,
 235                         struct_def: ast::StructDef,
 236                         generics: Generics) -> Gc<ast::Item>;
 237     fn item_struct(&self, span: Span, name: Ident,
 238                    struct_def: ast::StructDef) -> Gc<ast::Item>;
 239
 240     fn item_mod(&self, span: Span, inner_span: Span,
 241                 name: Ident, attrs: Vec<ast::Attribute>,
 242                 vi: Vec<ast::ViewItem>,
 243                 items: Vec<Gc<ast::Item>>) -> Gc<ast::Item>;
 244
 245     fn item_static(&self,
 246                    span: Span,
 247                    name: Ident,
 248                    ty: P<ast::Ty>,
 249                    mutbl: ast::Mutability,
 250                    expr: Gc<ast::Expr>)
 251                    -> Gc<ast::Item>;
 252
 253     fn item_ty_poly(&self,
 254                     span: Span,
 255                     name: Ident,
 256                     ty: P<ast::Ty>,
 257                     generics: Generics) -> Gc<ast::Item>;
 258     fn item_ty(&self, span: Span, name: Ident, ty: P<ast::Ty>) -> Gc<ast::Item>;
 259
 260     fn attribute(&self, sp: Span, mi: Gc<ast::MetaItem>) -> ast::Attribute;
 261
 262     fn meta_word(&self, sp: Span, w: InternedString) -> Gc<ast::MetaItem>;
 263     fn meta_list(&self,
 264                  sp: Span,
 265                  name: InternedString,
 266                  mis: Vec<Gc<ast::MetaItem>>)
 267                  -> Gc<ast::MetaItem>;
 268     fn meta_name_value(&self,
 269                        sp: Span,
 270                        name: InternedString,
 271                        value: ast::Lit_)
 272                        -> Gc<ast::MetaItem>;
 273
 274     fn view_use(&self, sp: Span,
 275                 vis: ast::Visibility, vp: Gc<ast::ViewPath>) -> ast::ViewItem;
 276     fn view_use_simple(&self, sp: Span, vis: ast::Visibility, path: ast::Path) -> ast::ViewItem;
 277     fn view_use_simple_(&self, sp: Span, vis: ast::Visibility,
 278                         ident: ast::Ident, path: ast::Path) -> ast::ViewItem;
 279     fn view_use_list(&self, sp: Span, vis: ast::Visibility,
 280                      path: Vec<ast::Ident> , imports: &[ast::Ident]) -> ast::ViewItem;
 281     fn view_use_glob(&self, sp: Span,
 282                      vis: ast::Visibility, path: Vec<ast::Ident> ) -> ast::ViewItem;
 283 }
 284
 285 impl<'a> AstBuilder for ExtCtxt<'a> {
 286     fn path(&self, span: Span, strs: Vec<ast::Ident> ) -> ast::Path {
 287         self.path_all(span, false, strs, Vec::new(), Vec::new())
 288     }
 289     fn path_ident(&self, span: Span, id: ast::Ident) -> ast::Path {
 290         self.path(span, vec!(id))
 291     }
 292     fn path_global(&self, span: Span, strs: Vec<ast::Ident> ) -> ast::Path {
 293         self.path_all(span, true, strs, Vec::new(), Vec::new())
 294     }
 295     fn path_all(&self,
 296                 sp: Span,
 297                 global: bool,
 298                 mut idents: Vec<ast::Ident> ,
 299                 lifetimes: Vec<ast::Lifetime>,
 300                 types: Vec<P<ast::Ty>> )
 301                 -> ast::Path {
 302         let last_identifier = idents.pop().unwrap();
 303         let mut segments: Vec<ast::PathSegment> = idents.move_iter()
 304                                                       .map(|ident| {
 305             ast::PathSegment {
 306                 identifier: ident,
 307                 lifetimes: Vec::new(),
 308                 types: OwnedSlice::empty(),
 309             }
 310         }).collect();
 311         segments.push(ast::PathSegment {
 312             identifier: last_identifier,
 313             lifetimes: lifetimes,
 314             types: OwnedSlice::from_vec(types),
 315         });
 316         ast::Path {
 317             span: sp,
 318             global: global,
 319             segments: segments,
 320         }
 321     }
 322
 323     fn ty_mt(&self, ty: P<ast::Ty>, mutbl: ast::Mutability) -> ast::MutTy {
 324         ast::MutTy {
 325             ty: ty,
 326             mutbl: mutbl
 327         }
 328     }
 329
 330     fn ty(&self, span: Span, ty: ast::Ty_) -> P<ast::Ty> {
 331         P(ast::Ty {
 332             id: ast::DUMMY_NODE_ID,
 333             span: span,
 334             node: ty
 335         })
 336     }
 337
 338     fn ty_path(&self, path: ast::Path, bounds: Option<OwnedSlice<ast::TyParamBound>>)
 339               -> P<ast::Ty> {
 340         self.ty(path.span,
 341                 ast::TyPath(path, bounds, ast::DUMMY_NODE_ID))
 342     }
 343
 344     // Might need to take bounds as an argument in the future, if you ever want
 345     // to generate a bounded existential trait type.
 346     fn ty_ident(&self, span: Span, ident: ast::Ident)
 347         -> P<ast::Ty> {
 348         self.ty_path(self.path_ident(span, ident), None)
 349     }
 350
 351     fn ty_rptr(&self,
 352                span: Span,
 353                ty: P<ast::Ty>,
 354                lifetime: Option<ast::Lifetime>,
 355                mutbl: ast::Mutability)
 356         -> P<ast::Ty> {
 357         self.ty(span,
 358                 ast::TyRptr(lifetime, self.ty_mt(ty, mutbl)))
 359     }
 360
 361     fn ty_uniq(&self, span: Span, ty: P<ast::Ty>) -> P<ast::Ty> {
 362         self.ty(span, ast::TyUniq(ty))
 363     }
 364
 365     fn ty_option(&self, ty: P<ast::Ty>) -> P<ast::Ty> {
 366         self.ty_path(
 367             self.path_all(DUMMY_SP,
 368                           true,
 369                           vec!(
 370                               self.ident_of("std"),
 371                               self.ident_of("option"),
 372                               self.ident_of("Option")
 373                           ),
 374                           Vec::new(),
 375                           vec!( ty )), None)
 376     }
 377
 378     fn ty_field_imm(&self, span: Span, name: Ident, ty: P<ast::Ty>) -> ast::TypeField {
 379         ast::TypeField {
 380             ident: name,
 381             mt: ast::MutTy { ty: ty, mutbl: ast::MutImmutable },
 382             span: span,
 383         }
 384     }
 385
 386     fn ty_infer(&self, span: Span) -> P<ast::Ty> {
 387         self.ty(span, ast::TyInfer)
 388     }
 389
 390     fn ty_nil(&self) -> P<ast::Ty> {
 391         P(ast::Ty {
 392             id: ast::DUMMY_NODE_ID,
 393             node: ast::TyNil,
 394             span: DUMMY_SP,
 395         })
 396     }
 397
 398     fn typaram(&self,
 399                span: Span,
 400                id: ast::Ident,
 401                bounds: OwnedSlice<ast::TyParamBound>,
 402                unbound: Option<ast::TyParamBound>,
 403                default: Option<P<ast::Ty>>) -> ast::TyParam {
 404         ast::TyParam {
 405             ident: id,
 406             id: ast::DUMMY_NODE_ID,
 407             bounds: bounds,
 408             unbound: unbound,
 409             default: default,
 410             span: span
 411         }
 412     }
 413
 414     // these are strange, and probably shouldn't be used outside of
 415     // pipes. Specifically, the global version possible generates
 416     // incorrect code.
 417     fn ty_vars(&self, ty_params: &OwnedSlice<ast::TyParam>) -> Vec<P<ast::Ty>> {
 418         ty_params.iter().map(|p| self.ty_ident(DUMMY_SP, p.ident)).collect()
 419     }
 420
 421     fn ty_vars_global(&self, ty_params: &OwnedSlice<ast::TyParam>) -> Vec<P<ast::Ty>> {
 422         ty_params.iter().map(|p| self.ty_path(
 423                 self.path_global(DUMMY_SP, vec!(p.ident)), None)).collect()
 424     }
 425
 426     fn strip_bounds(&self, generics: &Generics) -> Generics {
 427         let new_params = generics.ty_params.map(|ty_param| {
 428             ast::TyParam { bounds: OwnedSlice::empty(), unbound: None, ..*ty_param }
 429         });
 430         Generics {
 431             ty_params: new_params,
 432             .. (*generics).clone()
 433         }
 434     }
 435
 436     fn trait_ref(&self, path: ast::Path) -> ast::TraitRef {
 437         ast::TraitRef {
 438             path: path,
 439             ref_id: ast::DUMMY_NODE_ID
 440         }
 441     }
 442
 443     fn typarambound(&self, path: ast::Path) -> ast::TyParamBound {
 444         ast::TraitTyParamBound(self.trait_ref(path))
 445     }
 446
 447     fn lifetime(&self, span: Span, name: ast::Name) -> ast::Lifetime {
 448         ast::Lifetime { id: ast::DUMMY_NODE_ID, span: span, name: name }
 449     }
 450
 451     fn stmt_expr(&self, expr: Gc<ast::Expr>) -> Gc<ast::Stmt> {
 452         box(GC) respan(expr.span, ast::StmtSemi(expr, ast::DUMMY_NODE_ID))
 453     }
 454
 455     fn stmt_let(&self, sp: Span, mutbl: bool, ident: ast::Ident,
 456                 ex: Gc<ast::Expr>) -> Gc<ast::Stmt> {
 457         let pat = if mutbl {
 458             self.pat_ident_binding_mode(sp, ident, ast::BindByValue(ast::MutMutable))
 459         } else {
 460             self.pat_ident(sp, ident)
 461         };
 462         let local = box(GC) ast::Local {
 463             ty: self.ty_infer(sp),
 464             pat: pat,
 465             init: Some(ex),
 466             id: ast::DUMMY_NODE_ID,
 467             span: sp,
 468             source: ast::LocalLet,
 469         };
 470         let decl = respan(sp, ast::DeclLocal(local));
 471         box(GC) respan(sp, ast::StmtDecl(box(GC) decl, ast::DUMMY_NODE_ID))
 472     }
 473
 474     fn stmt_let_typed(&self,
 475                       sp: Span,
 476                       mutbl: bool,
 477                       ident: ast::Ident,
 478                       typ: P<ast::Ty>,
 479                       ex: Gc<ast::Expr>)
 480                       -> Gc<ast::Stmt> {
 481         let pat = if mutbl {
 482             self.pat_ident_binding_mode(sp, ident, ast::BindByValue(ast::MutMutable))
 483         } else {
 484             self.pat_ident(sp, ident)
 485         };
 486         let local = box(GC) ast::Local {
 487             ty: typ,
 488             pat: pat,
 489             init: Some(ex),
 490             id: ast::DUMMY_NODE_ID,
 491             span: sp,
 492             source: ast::LocalLet,
 493         };
 494         let decl = respan(sp, ast::DeclLocal(local));
 495         box(GC) respan(sp, ast::StmtDecl(box(GC) decl, ast::DUMMY_NODE_ID))
 496     }
 497
 498     fn block(&self,
 499              span: Span,
 500              stmts: Vec<Gc<ast::Stmt>>,
 501              expr: Option<Gc<Expr>>)
 502              -> P<ast::Block> {
 503         self.block_all(span, Vec::new(), stmts, expr)
 504     }
 505
 506     fn stmt_item(&self, sp: Span, item: Gc<ast::Item>) -> Gc<ast::Stmt> {
 507         let decl = respan(sp, ast::DeclItem(item));
 508         box(GC) respan(sp, ast::StmtDecl(box(GC) decl, ast::DUMMY_NODE_ID))
 509     }
 510
 511     fn block_expr(&self, expr: Gc<ast::Expr>) -> P<ast::Block> {
 512         self.block_all(expr.span, Vec::new(), Vec::new(), Some(expr))
 513     }
 514     fn block_all(&self,
 515                  span: Span,
 516                  view_items: Vec<ast::ViewItem> ,
 517                  stmts: Vec<Gc<ast::Stmt>>,
 518                  expr: Option<Gc<ast::Expr>>) -> P<ast::Block> {
 519             P(ast::Block {
 520                view_items: view_items,
 521                stmts: stmts,
 522                expr: expr,
 523                id: ast::DUMMY_NODE_ID,
 524                rules: ast::DefaultBlock,
 525                span: span,
 526             })
 527     }
 528
 529     fn expr(&self, span: Span, node: ast::Expr_) -> Gc<ast::Expr> {
 530         box(GC) ast::Expr {
 531             id: ast::DUMMY_NODE_ID,
 532             node: node,
 533             span: span,
 534         }
 535     }
 536
 537     fn expr_path(&self, path: ast::Path) -> Gc<ast::Expr> {
 538         self.expr(path.span, ast::ExprPath(path))
 539     }
 540
 541     fn expr_ident(&self, span: Span, id: ast::Ident) -> Gc<ast::Expr> {
 542         self.expr_path(self.path_ident(span, id))
 543     }
 544     fn expr_self(&self, span: Span) -> Gc<ast::Expr> {
 545         self.expr_ident(span, special_idents::self_)
 546     }
 547
 548     fn expr_binary(&self, sp: Span, op: ast::BinOp,
 549                    lhs: Gc<ast::Expr>, rhs: Gc<ast::Expr>) -> Gc<ast::Expr> {
 550         self.expr(sp, ast::ExprBinary(op, lhs, rhs))
 551     }
 552
 553     fn expr_deref(&self, sp: Span, e: Gc<ast::Expr>) -> Gc<ast::Expr> {
 554         self.expr_unary(sp, ast::UnDeref, e)
 555     }
 556     fn expr_unary(&self, sp: Span, op: ast::UnOp, e: Gc<ast::Expr>) -> Gc<ast::Expr> {
 557         self.expr(sp, ast::ExprUnary(op, e))
 558     }
 559
 560     fn expr_managed(&self, sp: Span, e: Gc<ast::Expr>) -> Gc<ast::Expr> {
 561         self.expr_unary(sp, ast::UnBox, e)
 562     }
 563
 564     fn expr_field_access(&self, sp: Span, expr: Gc<ast::Expr>, ident: ast::Ident) -> Gc<ast::Expr> {
 565         let field_name = token::get_ident(ident);
 566         let field_span = Span {
 567             lo: sp.lo - Pos::from_uint(field_name.get().len()),
 568             hi: sp.hi,
 569             expn_info: sp.expn_info,
 570         };
 571
 572         let id = Spanned { node: ident, span: field_span };
 573         self.expr(sp, ast::ExprField(expr, id, Vec::new()))
 574     }
 575     fn expr_addr_of(&self, sp: Span, e: Gc<ast::Expr>) -> Gc<ast::Expr> {
 576         self.expr(sp, ast::ExprAddrOf(ast::MutImmutable, e))
 577     }
 578     fn expr_mut_addr_of(&self, sp: Span, e: Gc<ast::Expr>) -> Gc<ast::Expr> {
 579         self.expr(sp, ast::ExprAddrOf(ast::MutMutable, e))
 580     }
 581
 582     fn expr_call(&self, span: Span, expr: Gc<ast::Expr>,
 583                  args: Vec<Gc<ast::Expr>>) -> Gc<ast::Expr> {
 584         self.expr(span, ast::ExprCall(expr, args))
 585     }
 586     fn expr_call_ident(&self, span: Span, id: ast::Ident,
 587                        args: Vec<Gc<ast::Expr>>) -> Gc<ast::Expr> {
 588         self.expr(span, ast::ExprCall(self.expr_ident(span, id), args))
 589     }
 590     fn expr_call_global(&self, sp: Span, fn_path: Vec<ast::Ident> ,
 591                       args: Vec<Gc<ast::Expr>> ) -> Gc<ast::Expr> {
 592         let pathexpr = self.expr_path(self.path_global(sp, fn_path));
 593         self.expr_call(sp, pathexpr, args)
 594     }
 595     fn expr_method_call(&self, span: Span,
 596                         expr: Gc<ast::Expr>,
 597                         ident: ast::Ident,
 598                         mut args: Vec<Gc<ast::Expr>> ) -> Gc<ast::Expr> {
 599         let id = Spanned { node: ident, span: span };
 600         args.unshift(expr);
 601         self.expr(span, ast::ExprMethodCall(id, Vec::new(), args))
 602     }
 603     fn expr_block(&self, b: P<ast::Block>) -> Gc<ast::Expr> {
 604         self.expr(b.span, ast::ExprBlock(b))
 605     }
 606     fn field_imm(&self, span: Span, name: Ident, e: Gc<ast::Expr>) -> ast::Field {
 607         ast::Field { ident: respan(span, name), expr: e, span: span }
 608     }
 609     fn expr_struct(&self, span: Span, path: ast::Path, fields: Vec<ast::Field> ) -> Gc<ast::Expr> {
 610         self.expr(span, ast::ExprStruct(path, fields, None))
 611     }
 612     fn expr_struct_ident(&self, span: Span,
 613                          id: ast::Ident, fields: Vec<ast::Field> ) -> Gc<ast::Expr> {
 614         self.expr_struct(span, self.path_ident(span, id), fields)
 615     }
 616
 617     fn expr_lit(&self, sp: Span, lit: ast::Lit_) -> Gc<ast::Expr> {
 618         self.expr(sp, ast::ExprLit(box(GC) respan(sp, lit)))
 619     }
 620     fn expr_uint(&self, span: Span, i: uint) -> Gc<ast::Expr> {
 621         self.expr_lit(span, ast::LitUint(i as u64, ast::TyU))
 622     }
 623     fn expr_int(&self, sp: Span, i: int) -> Gc<ast::Expr> {
 624         self.expr_lit(sp, ast::LitInt(i as i64, ast::TyI))
 625     }
 626     fn expr_u8(&self, sp: Span, u: u8) -> Gc<ast::Expr> {
 627         self.expr_lit(sp, ast::LitUint(u as u64, ast::TyU8))
 628     }
 629     fn expr_bool(&self, sp: Span, value: bool) -> Gc<ast::Expr> {
 630         self.expr_lit(sp, ast::LitBool(value))
 631     }
 632
 633     fn expr_vstore(&self, sp: Span, expr: Gc<ast::Expr>, vst: ast::ExprVstore) -> Gc<ast::Expr> {
 634         self.expr(sp, ast::ExprVstore(expr, vst))
 635     }
 636     fn expr_vec(&self, sp: Span, exprs: Vec<Gc<ast::Expr>> ) -> Gc<ast::Expr> {
 637         self.expr(sp, ast::ExprVec(exprs))
 638     }
 639     fn expr_vec_ng(&self, sp: Span) -> Gc<ast::Expr> {
 640         self.expr_call_global(sp,
 641                               vec!(self.ident_of("std"),
 642                                    self.ident_of("vec"),
 643                                    self.ident_of("Vec"),
 644                                    self.ident_of("new")),
 645                               Vec::new())
 646     }
 647     fn expr_vec_slice(&self, sp: Span, exprs: Vec<Gc<ast::Expr>> ) -> Gc<ast::Expr> {
 648         self.expr_vstore(sp, self.expr_vec(sp, exprs), ast::ExprVstoreSlice)
 649     }
 650     fn expr_str(&self, sp: Span, s: InternedString) -> Gc<ast::Expr> {
 651         self.expr_lit(sp, ast::LitStr(s, ast::CookedStr))
 652     }
 653     fn expr_str_uniq(&self, sp: Span, s: InternedString) -> Gc<ast::Expr> {
 654         self.expr_vstore(sp, self.expr_str(sp, s), ast::ExprVstoreUniq)
 655     }
 656
 657
 658     fn expr_cast(&self, sp: Span, expr: Gc<ast::Expr>, ty: P<ast::Ty>) -> Gc<ast::Expr> {
 659         self.expr(sp, ast::ExprCast(expr, ty))
 660     }
 661
 662
 663     fn expr_some(&self, sp: Span, expr: Gc<ast::Expr>) -> Gc<ast::Expr> {
 664         let some = vec!(
 665             self.ident_of("std"),
 666             self.ident_of("option"),
 667             self.ident_of("Some"));
 668         self.expr_call_global(sp, some, vec!(expr))
 669     }
 670
 671     fn expr_none(&self, sp: Span) -> Gc<ast::Expr> {
 672         let none = self.path_global(sp, vec!(
 673             self.ident_of("std"),
 674             self.ident_of("option"),
 675             self.ident_of("None")));
 676         self.expr_path(none)
 677     }
 678
 679     fn expr_tuple(&self, sp: Span, exprs: Vec<Gc<ast::Expr>>) -> Gc<ast::Expr> {
 680         self.expr(sp, ast::ExprTup(exprs))
 681     }
 682
 683     fn expr_fail(&self, span: Span, msg: InternedString) -> Gc<ast::Expr> {
 684         let loc = self.codemap().lookup_char_pos(span.lo);
 685         self.expr_call_global(
 686             span,
 687             vec!(
 688                 self.ident_of("std"),
 689                 self.ident_of("rt"),
 690                 self.ident_of("begin_unwind")),
 691             vec!(
 692                 self.expr_str(span, msg),
 693                 self.expr_str(span,
 694                               token::intern_and_get_ident(loc.file
 695                                                              .name
 696                                                              .as_slice())),
 697                 self.expr_uint(span, loc.line)))
 698     }
 699
 700     fn expr_unreachable(&self, span: Span) -> Gc<ast::Expr> {
 701         self.expr_fail(span,
 702                        InternedString::new(
 703                            "internal error: entered unreachable code"))
 704     }
 705
 706     fn expr_ok(&self, sp: Span, expr: Gc<ast::Expr>) -> Gc<ast::Expr> {
 707         let ok = vec!(
 708             self.ident_of("std"),
 709             self.ident_of("result"),
 710             self.ident_of("Ok"));
 711         self.expr_call_global(sp, ok, vec!(expr))
 712     }
 713
 714     fn expr_err(&self, sp: Span, expr: Gc<ast::Expr>) -> Gc<ast::Expr> {
 715         let err = vec!(
 716             self.ident_of("std"),
 717             self.ident_of("result"),
 718             self.ident_of("Err"));
 719         self.expr_call_global(sp, err, vec!(expr))
 720     }
 721
 722     fn expr_try(&self, sp: Span, head: Gc<ast::Expr>) -> Gc<ast::Expr> {
 723         let ok = self.ident_of("Ok");
 724         let ok_path = self.path_ident(sp, ok);
 725         let err = self.ident_of("Err");
 726         let err_path = self.path_ident(sp, err);
 727
 728         let binding_variable = self.ident_of("__try_var");
 729         let binding_pat = self.pat_ident(sp, binding_variable);
 730         let binding_expr = self.expr_ident(sp, binding_variable);
 731
 732         // Ok(__try_var) pattern
 733         let ok_pat = self.pat_enum(sp, ok_path, vec!(binding_pat));
 734
 735         // Err(__try_var)  (pattern and expression resp.)
 736         let err_pat = self.pat_enum(sp, err_path, vec!(binding_pat));
 737         let err_inner_expr = self.expr_call_ident(sp, err, vec!(binding_expr));
 738         // return Err(__try_var)
 739         let err_expr = self.expr(sp, ast::ExprRet(Some(err_inner_expr)));
 740
 741         // Ok(__try_var) => __try_var
 742         let ok_arm = self.arm(sp, vec!(ok_pat), binding_expr);
 743         // Err(__try_var) => return Err(__try_var)
 744         let err_arm = self.arm(sp, vec!(err_pat), err_expr);
 745
 746         // match head { Ok() => ..., Err() => ... }
 747         self.expr_match(sp, head, vec!(ok_arm, err_arm))
 748     }
 749
 750
 751     fn pat(&self, span: Span, pat: ast::Pat_) -> Gc<ast::Pat> {
 752         box(GC) ast::Pat { id: ast::DUMMY_NODE_ID, node: pat, span: span }
 753     }
 754     fn pat_wild(&self, span: Span) -> Gc<ast::Pat> {
 755         self.pat(span, ast::PatWild)
 756     }
 757     fn pat_lit(&self, span: Span, expr: Gc<ast::Expr>) -> Gc<ast::Pat> {
 758         self.pat(span, ast::PatLit(expr))
 759     }
 760     fn pat_ident(&self, span: Span, ident: ast::Ident) -> Gc<ast::Pat> {
 761         self.pat_ident_binding_mode(span, ident, ast::BindByValue(ast::MutImmutable))
 762     }
 763
 764     fn pat_ident_binding_mode(&self,
 765                               span: Span,
 766                               ident: ast::Ident,
 767                               bm: ast::BindingMode) -> Gc<ast::Pat> {
 768         let pat = ast::PatIdent(bm, Spanned{span: span, node: ident}, None);
 769         self.pat(span, pat)
 770     }
 771     fn pat_enum(&self, span: Span, path: ast::Path, subpats: Vec<Gc<ast::Pat>> ) -> Gc<ast::Pat> {
 772         let pat = ast::PatEnum(path, Some(subpats));
 773         self.pat(span, pat)
 774     }
 775     fn pat_struct(&self, span: Span,
 776                   path: ast::Path, field_pats: Vec<ast::FieldPat> ) -> Gc<ast::Pat> {
 777         let pat = ast::PatStruct(path, field_pats, false);
 778         self.pat(span, pat)
 779     }
 780
 781     fn arm(&self, _span: Span, pats: Vec<Gc<ast::Pat>> , expr: Gc<ast::Expr>) -> ast::Arm {
 782         ast::Arm {
 783             attrs: vec!(),
 784             pats: pats,
 785             guard: None,
 786             body: expr
 787         }
 788     }
 789
 790     fn arm_unreachable(&self, span: Span) -> ast::Arm {
 791         self.arm(span, vec!(self.pat_wild(span)), self.expr_unreachable(span))
 792     }
 793
 794     fn expr_match(&self, span: Span, arg: Gc<ast::Expr>,
 795                   arms: Vec<ast::Arm>) -> Gc<Expr> {
 796         self.expr(span, ast::ExprMatch(arg, arms))
 797     }
 798
 799     fn expr_if(&self, span: Span,
 800                cond: Gc<ast::Expr>, then: Gc<ast::Expr>,
 801                els: Option<Gc<ast::Expr>>) -> Gc<ast::Expr> {
 802         let els = els.map(|x| self.expr_block(self.block_expr(x)));
 803         self.expr(span, ast::ExprIf(cond, self.block_expr(then), els))
 804     }
 805
 806     fn lambda_fn_decl(&self, span: Span,
 807                       fn_decl: P<ast::FnDecl>, blk: P<ast::Block>) -> Gc<ast::Expr> {
 808         self.expr(span, ast::ExprFnBlock(fn_decl, blk))
 809     }
 810     fn lambda(&self, span: Span, ids: Vec<ast::Ident> , blk: P<ast::Block>) -> Gc<ast::Expr> {
 811         let fn_decl = self.fn_decl(
 812             ids.iter().map(|id| self.arg(span, *id, self.ty_infer(span))).collect(),
 813             self.ty_infer(span));
 814
 815         self.expr(span, ast::ExprFnBlock(fn_decl, blk))
 816     }
 817     fn lambda0(&self, span: Span, blk: P<ast::Block>) -> Gc<ast::Expr> {
 818         self.lambda(span, Vec::new(), blk)
 819     }
 820
 821     fn lambda1(&self, span: Span, blk: P<ast::Block>, ident: ast::Ident) -> Gc<ast::Expr> {
 822         self.lambda(span, vec!(ident), blk)
 823     }
 824
 825     fn lambda_expr(&self, span: Span, ids: Vec<ast::Ident> , expr: Gc<ast::Expr>) -> Gc<ast::Expr> {
 826         self.lambda(span, ids, self.block_expr(expr))
 827     }
 828     fn lambda_expr_0(&self, span: Span, expr: Gc<ast::Expr>) -> Gc<ast::Expr> {
 829         self.lambda0(span, self.block_expr(expr))
 830     }
 831     fn lambda_expr_1(&self, span: Span, expr: Gc<ast::Expr>, ident: ast::Ident) -> Gc<ast::Expr> {
 832         self.lambda1(span, self.block_expr(expr), ident)
 833     }
 834
 835     fn lambda_stmts(&self,
 836                     span: Span,
 837                     ids: Vec<ast::Ident>,
 838                     stmts: Vec<Gc<ast::Stmt>>)
 839                     -> Gc<ast::Expr> {
 840         self.lambda(span, ids, self.block(span, stmts, None))
 841     }
 842     fn lambda_stmts_0(&self, span: Span,
 843                       stmts: Vec<Gc<ast::Stmt>>) -> Gc<ast::Expr> {
 844         self.lambda0(span, self.block(span, stmts, None))
 845     }
 846     fn lambda_stmts_1(&self, span: Span, stmts: Vec<Gc<ast::Stmt>>,
 847                       ident: ast::Ident) -> Gc<ast::Expr> {
 848         self.lambda1(span, self.block(span, stmts, None), ident)
 849     }
 850
 851     fn arg(&self, span: Span, ident: ast::Ident, ty: P<ast::Ty>) -> ast::Arg {
 852         let arg_pat = self.pat_ident(span, ident);
 853         ast::Arg {
 854             ty: ty,
 855             pat: arg_pat,
 856             id: ast::DUMMY_NODE_ID
 857         }
 858     }
 859
 860     // FIXME unused self
 861     fn fn_decl(&self, inputs: Vec<ast::Arg> , output: P<ast::Ty>) -> P<ast::FnDecl> {
 862         P(ast::FnDecl {
 863             inputs: inputs,
 864             output: output,
 865             cf: ast::Return,
 866             variadic: false
 867         })
 868     }
 869
 870     fn item(&self, span: Span,
 871             name: Ident, attrs: Vec<ast::Attribute>,
 872             node: ast::Item_) -> Gc<ast::Item> {
 873         // FIXME: Would be nice if our generated code didn't violate
 874         // Rust coding conventions
 875         box(GC) ast::Item { ident: name,
 876                     attrs: attrs,
 877                     id: ast::DUMMY_NODE_ID,
 878                     node: node,
 879                     vis: ast::Inherited,
 880                     span: span }
 881     }
 882
 883     fn item_fn_poly(&self,
 884                     span: Span,
 885                     name: Ident,
 886                     inputs: Vec<ast::Arg> ,
 887                     output: P<ast::Ty>,
 888                     generics: Generics,
 889                     body: P<ast::Block>) -> Gc<ast::Item> {
 890         self.item(span,
 891                   name,
 892                   Vec::new(),
 893                   ast::ItemFn(self.fn_decl(inputs, output),
 894                               ast::NormalFn,
 895                               abi::Rust,
 896                               generics,
 897                               body))
 898     }
 899
 900     fn item_fn(&self,
 901                span: Span,
 902                name: Ident,
 903                inputs: Vec<ast::Arg> ,
 904                output: P<ast::Ty>,
 905                body: P<ast::Block>
 906               ) -> Gc<ast::Item> {
 907         self.item_fn_poly(
 908             span,
 909             name,
 910             inputs,
 911             output,
 912             ast_util::empty_generics(),
 913             body)
 914     }
 915
 916     fn variant(&self, span: Span, name: Ident, tys: Vec<P<ast::Ty>> ) -> ast::Variant {
 917         let args = tys.move_iter().map(|ty| {
 918             ast::VariantArg { ty: ty, id: ast::DUMMY_NODE_ID }
 919         }).collect();
 920
 921         respan(span,
 922                ast::Variant_ {
 923                    name: name,
 924                    attrs: Vec::new(),
 925                    kind: ast::TupleVariantKind(args),
 926                    id: ast::DUMMY_NODE_ID,
 927                    disr_expr: None,
 928                    vis: ast::Public
 929                })
 930     }
 931
 932     fn item_enum_poly(&self, span: Span, name: Ident,
 933                       enum_definition: ast::EnumDef,
 934                       generics: Generics) -> Gc<ast::Item> {
 935         self.item(span, name, Vec::new(), ast::ItemEnum(enum_definition, generics))
 936     }
 937
 938     fn item_enum(&self, span: Span, name: Ident,
 939                  enum_definition: ast::EnumDef) -> Gc<ast::Item> {
 940         self.item_enum_poly(span, name, enum_definition,
 941                             ast_util::empty_generics())
 942     }
 943
 944     fn item_struct(&self, span: Span, name: Ident,
 945                    struct_def: ast::StructDef) -> Gc<ast::Item> {
 946         self.item_struct_poly(
 947             span,
 948             name,
 949             struct_def,
 950             ast_util::empty_generics()
 951         )
 952     }
 953
 954     fn item_struct_poly(&self, span: Span, name: Ident,
 955         struct_def: ast::StructDef, generics: Generics) -> Gc<ast::Item> {
 956         self.item(span, name, Vec::new(), ast::ItemStruct(box(GC) struct_def, generics))
 957     }
 958
 959     fn item_mod(&self, span: Span, inner_span: Span, name: Ident,
 960                 attrs: Vec<ast::Attribute> ,
 961                 vi: Vec<ast::ViewItem> ,
 962                 items: Vec<Gc<ast::Item>>) -> Gc<ast::Item> {
 963         self.item(
 964             span,
 965             name,
 966             attrs,
 967             ast::ItemMod(ast::Mod {
 968                 inner: inner_span,
 969                 view_items: vi,
 970                 items: items,
 971             })
 972         )
 973     }
 974
 975     fn item_static(&self,
 976                    span: Span,
 977                    name: Ident,
 978                    ty: P<ast::Ty>,
 979                    mutbl: ast::Mutability,
 980                    expr: Gc<ast::Expr>)
 981                    -> Gc<ast::Item> {
 982         self.item(span, name, Vec::new(), ast::ItemStatic(ty, mutbl, expr))
 983     }
 984
 985     fn item_ty_poly(&self, span: Span, name: Ident, ty: P<ast::Ty>,
 986                     generics: Generics) -> Gc<ast::Item> {
 987         self.item(span, name, Vec::new(), ast::ItemTy(ty, generics))
 988     }
 989
 990     fn item_ty(&self, span: Span, name: Ident, ty: P<ast::Ty>) -> Gc<ast::Item> {
 991         self.item_ty_poly(span, name, ty, ast_util::empty_generics())
 992     }
 993
 994     fn attribute(&self, sp: Span, mi: Gc<ast::MetaItem>) -> ast::Attribute {
 995         respan(sp, ast::Attribute_ {
 996             id: attr::mk_attr_id(),
 997             style: ast::AttrOuter,
 998             value: mi,
 999             is_sugared_doc: false,
1000         })
1001     }
1002
1003     fn meta_word(&self, sp: Span, w: InternedString) -> Gc<ast::MetaItem> {
1004         box(GC) respan(sp, ast::MetaWord(w))
1005     }
1006     fn meta_list(&self,
1007                  sp: Span,
1008                  name: InternedString,
1009                  mis: Vec<Gc<ast::MetaItem>> )
1010                  -> Gc<ast::MetaItem> {
1011         box(GC) respan(sp, ast::MetaList(name, mis))
1012     }
1013     fn meta_name_value(&self,
1014                        sp: Span,
1015                        name: InternedString,
1016                        value: ast::Lit_)
1017                        -> Gc<ast::MetaItem> {
1018         box(GC) respan(sp, ast::MetaNameValue(name, respan(sp, value)))
1019     }
1020
1021     fn view_use(&self, sp: Span,
1022                 vis: ast::Visibility, vp: Gc<ast::ViewPath>) -> ast::ViewItem {
1023         ast::ViewItem {
1024             node: ast::ViewItemUse(vp),
1025             attrs: Vec::new(),
1026             vis: vis,
1027             span: sp
1028         }
1029     }
1030
1031     fn view_use_simple(&self, sp: Span, vis: ast::Visibility, path: ast::Path) -> ast::ViewItem {
1032         let last = path.segments.last().unwrap().identifier;
1033         self.view_use_simple_(sp, vis, last, path)
1034     }
1035
1036     fn view_use_simple_(&self, sp: Span, vis: ast::Visibility,
1037                         ident: ast::Ident, path: ast::Path) -> ast::ViewItem {
1038         self.view_use(sp, vis,
1039                       box(GC) respan(sp,
1040                            ast::ViewPathSimple(ident,
1041                                                path,
1042                                                ast::DUMMY_NODE_ID)))
1043     }
1044
1045     fn view_use_list(&self, sp: Span, vis: ast::Visibility,
1046                      path: Vec<ast::Ident> , imports: &[ast::Ident]) -> ast::ViewItem {
1047         let imports = imports.iter().map(|id| {
1048             respan(sp, ast::PathListIdent { name: *id, id: ast::DUMMY_NODE_ID })
1049         }).collect();
1050
1051         self.view_use(sp, vis,
1052                       box(GC) respan(sp,
1053                            ast::ViewPathList(self.path(sp, path),
1054                                              imports,
1055                                              ast::DUMMY_NODE_ID)))
1056     }
1057
1058     fn view_use_glob(&self, sp: Span,
1059                      vis: ast::Visibility, path: Vec<ast::Ident> ) -> ast::ViewItem {
1060         self.view_use(sp, vis,
1061                       box(GC) respan(sp,
1062                            ast::ViewPathGlob(self.path(sp, path), ast::DUMMY_NODE_ID)))
1063     }
1064 }
1065
1066 struct Duplicator<'a>;
1067
1068 impl<'a> Folder for Duplicator<'a> {
1069     fn new_id(&mut self, _: NodeId) -> NodeId {
1070         ast::DUMMY_NODE_ID
1071     }
1072 }
1073
1074 pub trait Duplicate {
1075     //
1076     // Duplication functions
1077     //
1078     // These functions just duplicate AST nodes.
1079     //
1080
1081     fn duplicate(&self, cx: &ExtCtxt) -> Self;
1082 }
1083
1084 impl Duplicate for Gc<ast::Expr> {
1085     fn duplicate(&self, _: &ExtCtxt) -> Gc<ast::Expr> {
1086         let mut folder = Duplicator;
1087         folder.fold_expr(*self)
1088     }
1089 }