src/libsyntax/config.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 use attr::AttrMetaMethods;
  12 use diagnostic::SpanHandler;
  13 use fold::Folder;
  14 use {ast, fold, attr};
  15 use codemap::Spanned;
  16 use ptr::P;
  17
  18 use util::small_vector::SmallVector;
  19
  20 /// A folder that strips out items that do not belong in the current
  21 /// configuration.
  22 struct Context<F> where F: FnMut(&[ast::Attribute]) -> bool {
  23     in_cfg: F,
  24 }
  25
  26 // Support conditional compilation by transforming the AST, stripping out
  27 // any items that do not belong in the current configuration
  28 pub fn strip_unconfigured_items(diagnostic: &SpanHandler, krate: ast::Crate) -> ast::Crate {
  29     let config = krate.config.clone();
  30     strip_items(krate, |attrs| in_cfg(diagnostic, config.as_slice(), attrs))
  31 }
  32
  33 impl<F> fold::Folder for Context<F> where F: FnMut(&[ast::Attribute]) -> bool {
  34     fn fold_mod(&mut self, module: ast::Mod) -> ast::Mod {
  35         fold_mod(self, module)
  36     }
  37     fn fold_block(&mut self, block: P<ast::Block>) -> P<ast::Block> {
  38         fold_block(self, block)
  39     }
  40     fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
  41         fold_foreign_mod(self, foreign_mod)
  42     }
  43     fn fold_item_underscore(&mut self, item: ast::Item_) -> ast::Item_ {
  44         fold_item_underscore(self, item)
  45     }
  46     fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
  47         fold_expr(self, expr)
  48     }
  49     fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
  50         fold::noop_fold_mac(mac, self)
  51     }
  52     fn fold_item(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
  53         fold_item(self, item)
  54     }
  55 }
  56
  57 pub fn strip_items<F>(krate: ast::Crate, in_cfg: F) -> ast::Crate where
  58     F: FnMut(&[ast::Attribute]) -> bool,
  59 {
  60     let mut ctxt = Context {
  61         in_cfg: in_cfg,
  62     };
  63     ctxt.fold_crate(krate)
  64 }
  65
  66 fn filter_view_item<F>(cx: &mut Context<F>,
  67                        view_item: ast::ViewItem)
  68                        -> Option<ast::ViewItem> where
  69     F: FnMut(&[ast::Attribute]) -> bool
  70 {
  71     if view_item_in_cfg(cx, &view_item) {
  72         Some(view_item)
  73     } else {
  74         None
  75     }
  76 }
  77
  78 fn fold_mod<F>(cx: &mut Context<F>,
  79                ast::Mod {inner,
  80                view_items, items}: ast::Mod) -> ast::Mod where
  81     F: FnMut(&[ast::Attribute]) -> bool
  82 {
  83     ast::Mod {
  84         inner: inner,
  85         view_items: view_items.into_iter().filter_map(|a| {
  86             filter_view_item(cx, a).map(|x| cx.fold_view_item(x))
  87         }).collect(),
  88         items: items.into_iter().flat_map(|a| {
  89             cx.fold_item(a).into_iter()
  90         }).collect()
  91     }
  92 }
  93
  94 fn filter_foreign_item<F>(cx: &mut Context<F>,
  95                           item: P<ast::ForeignItem>)
  96                           -> Option<P<ast::ForeignItem>> where
  97     F: FnMut(&[ast::Attribute]) -> bool
  98 {
  99     if foreign_item_in_cfg(cx, &*item) {
 100         Some(item)
 101     } else {
 102         None
 103     }
 104 }
 105
 106 fn fold_foreign_mod<F>(cx: &mut Context<F>,
 107                        ast::ForeignMod {abi, view_items, items}: ast::ForeignMod)
 108                        -> ast::ForeignMod where
 109     F: FnMut(&[ast::Attribute]) -> bool
 110 {
 111     ast::ForeignMod {
 112         abi: abi,
 113         view_items: view_items.into_iter().filter_map(|a| {
 114             filter_view_item(cx, a).map(|x| cx.fold_view_item(x))
 115         }).collect(),
 116         items: items.into_iter()
 117                     .filter_map(|a| filter_foreign_item(cx, a))
 118                     .collect()
 119     }
 120 }
 121
 122 fn fold_item<F>(cx: &mut Context<F>, item: P<ast::Item>) -> SmallVector<P<ast::Item>> where
 123     F: FnMut(&[ast::Attribute]) -> bool
 124 {
 125     if item_in_cfg(cx, &*item) {
 126         SmallVector::one(item.map(|i| cx.fold_item_simple(i)))
 127     } else {
 128         SmallVector::zero()
 129     }
 130 }
 131
 132 fn fold_item_underscore<F>(cx: &mut Context<F>, item: ast::Item_) -> ast::Item_ where
 133     F: FnMut(&[ast::Attribute]) -> bool
 134 {
 135     let item = match item {
 136         ast::ItemImpl(u, a, b, c, impl_items) => {
 137             let impl_items = impl_items.into_iter()
 138                                        .filter(|ii| impl_item_in_cfg(cx, ii))
 139                                        .collect();
 140             ast::ItemImpl(u, a, b, c, impl_items)
 141         }
 142         ast::ItemTrait(u, a, b, methods) => {
 143             let methods = methods.into_iter()
 144                                  .filter(|m| trait_method_in_cfg(cx, m))
 145                                  .collect();
 146             ast::ItemTrait(u, a, b, methods)
 147         }
 148         ast::ItemStruct(def, generics) => {
 149             ast::ItemStruct(fold_struct(cx, def), generics)
 150         }
 151         ast::ItemEnum(def, generics) => {
 152             let variants = def.variants.into_iter().filter_map(|v| {
 153                 if !(cx.in_cfg)(v.node.attrs.as_slice()) {
 154                     None
 155                 } else {
 156                     Some(v.map(|Spanned {node: ast::Variant_ {id, name, attrs, kind,
 157                                                               disr_expr, vis}, span}| {
 158                         Spanned {
 159                             node: ast::Variant_ {
 160                                 id: id,
 161                                 name: name,
 162                                 attrs: attrs,
 163                                 kind: match kind {
 164                                     ast::TupleVariantKind(..) => kind,
 165                                     ast::StructVariantKind(def) => {
 166                                         ast::StructVariantKind(fold_struct(cx, def))
 167                                     }
 168                                 },
 169                                 disr_expr: disr_expr,
 170                                 vis: vis
 171                             },
 172                             span: span
 173                         }
 174                     }))
 175                 }
 176             });
 177             ast::ItemEnum(ast::EnumDef {
 178                 variants: variants.collect(),
 179             }, generics)
 180         }
 181         item => item,
 182     };
 183
 184     fold::noop_fold_item_underscore(item, cx)
 185 }
 186
 187 fn fold_struct<F>(cx: &mut Context<F>, def: P<ast::StructDef>) -> P<ast::StructDef> where
 188     F: FnMut(&[ast::Attribute]) -> bool
 189 {
 190     def.map(|ast::StructDef { fields, ctor_id }| {
 191         ast::StructDef {
 192             fields: fields.into_iter().filter(|m| {
 193                 (cx.in_cfg)(m.node.attrs.as_slice())
 194             }).collect(),
 195             ctor_id: ctor_id,
 196         }
 197     })
 198 }
 199
 200 fn retain_stmt<F>(cx: &mut Context<F>, stmt: &ast::Stmt) -> bool where
 201     F: FnMut(&[ast::Attribute]) -> bool
 202 {
 203     match stmt.node {
 204         ast::StmtDecl(ref decl, _) => {
 205             match decl.node {
 206                 ast::DeclItem(ref item) => {
 207                     item_in_cfg(cx, &**item)
 208                 }
 209                 _ => true
 210             }
 211         }
 212         _ => true
 213     }
 214 }
 215
 216 fn fold_block<F>(cx: &mut Context<F>, b: P<ast::Block>) -> P<ast::Block> where
 217     F: FnMut(&[ast::Attribute]) -> bool
 218 {
 219     b.map(|ast::Block {id, view_items, stmts, expr, rules, span}| {
 220         let resulting_stmts: Vec<P<ast::Stmt>> =
 221             stmts.into_iter().filter(|a| retain_stmt(cx, &**a)).collect();
 222         let resulting_stmts = resulting_stmts.into_iter()
 223             .flat_map(|stmt| cx.fold_stmt(stmt).into_iter())
 224             .collect();
 225         let filtered_view_items = view_items.into_iter().filter_map(|a| {
 226             filter_view_item(cx, a).map(|x| cx.fold_view_item(x))
 227         }).collect();
 228         ast::Block {
 229             id: id,
 230             view_items: filtered_view_items,
 231             stmts: resulting_stmts,
 232             expr: expr.map(|x| cx.fold_expr(x)),
 233             rules: rules,
 234             span: span,
 235         }
 236     })
 237 }
 238
 239 fn fold_expr<F>(cx: &mut Context<F>, expr: P<ast::Expr>) -> P<ast::Expr> where
 240     F: FnMut(&[ast::Attribute]) -> bool
 241 {
 242     expr.map(|ast::Expr {id, span, node}| {
 243         fold::noop_fold_expr(ast::Expr {
 244             id: id,
 245             node: match node {
 246                 ast::ExprMatch(m, arms, source) => {
 247                     ast::ExprMatch(m, arms.into_iter()
 248                                         .filter(|a| (cx.in_cfg)(a.attrs.as_slice()))
 249                                         .collect(), source)
 250                 }
 251                 _ => node
 252             },
 253             span: span
 254         }, cx)
 255     })
 256 }
 257
 258 fn item_in_cfg<F>(cx: &mut Context<F>, item: &ast::Item) -> bool where
 259     F: FnMut(&[ast::Attribute]) -> bool
 260 {
 261     return (cx.in_cfg)(item.attrs.as_slice());
 262 }
 263
 264 fn foreign_item_in_cfg<F>(cx: &mut Context<F>, item: &ast::ForeignItem) -> bool where
 265     F: FnMut(&[ast::Attribute]) -> bool
 266 {
 267     return (cx.in_cfg)(item.attrs.as_slice());
 268 }
 269
 270 fn view_item_in_cfg<F>(cx: &mut Context<F>, item: &ast::ViewItem) -> bool where
 271     F: FnMut(&[ast::Attribute]) -> bool
 272 {
 273     return (cx.in_cfg)(item.attrs.as_slice());
 274 }
 275
 276 fn trait_method_in_cfg<F>(cx: &mut Context<F>, meth: &ast::TraitItem) -> bool where
 277     F: FnMut(&[ast::Attribute]) -> bool
 278 {
 279     match *meth {
 280         ast::RequiredMethod(ref meth) => (cx.in_cfg)(meth.attrs.as_slice()),
 281         ast::ProvidedMethod(ref meth) => (cx.in_cfg)(meth.attrs.as_slice()),
 282         ast::TypeTraitItem(ref typ) => (cx.in_cfg)(typ.attrs.as_slice()),
 283     }
 284 }
 285
 286 fn impl_item_in_cfg<F>(cx: &mut Context<F>, impl_item: &ast::ImplItem) -> bool where
 287     F: FnMut(&[ast::Attribute]) -> bool
 288 {
 289     match *impl_item {
 290         ast::MethodImplItem(ref meth) => (cx.in_cfg)(meth.attrs.as_slice()),
 291         ast::TypeImplItem(ref typ) => (cx.in_cfg)(typ.attrs.as_slice()),
 292     }
 293 }
 294
 295 // Determine if an item should be translated in the current crate
 296 // configuration based on the item's attributes
 297 fn in_cfg(diagnostic: &SpanHandler, cfg: &[P<ast::MetaItem>], attrs: &[ast::Attribute]) -> bool {
 298     attrs.iter().all(|attr| {
 299         let mis = match attr.node.value.node {
 300             ast::MetaList(_, ref mis) if attr.check_name("cfg") => mis,
 301             _ => return true
 302         };
 303
 304         if mis.len() != 1 {
 305             diagnostic.span_err(attr.span, "expected 1 cfg-pattern");
 306             return true;
 307         }
 308
 309         attr::cfg_matches(diagnostic, cfg, &*mis[0])
 310     })
 311 }