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