src/librustc/front/std_inject.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
  12 use driver::session::Session;
  13
  14 use std::vec;
  15 use syntax::ast;
  16 use syntax::attr;
  17 use syntax::codemap::dummy_sp;
  18 use syntax::codemap;
  19 use syntax::fold::ast_fold;
  20 use syntax::fold;
  21 use syntax::opt_vec;
  22 use syntax::util::small_vector::SmallVector;
  23
  24 pub static VERSION: &'static str = "0.9-pre";
  25
  26 pub fn maybe_inject_libstd_ref(sess: Session, crate: ast::Crate)
  27                                -> ast::Crate {
  28     if use_std(&crate) {
  29         inject_libstd_ref(sess, crate)
  30     } else {
  31         crate
  32     }
  33 }
  34
  35 fn use_std(crate: &ast::Crate) -> bool {
  36     !attr::contains_name(crate.attrs, "no_std")
  37 }
  38
  39 fn use_uv(crate: &ast::Crate) -> bool {
  40     !attr::contains_name(crate.attrs, "no_uv")
  41 }
  42
  43 fn no_prelude(attrs: &[ast::Attribute]) -> bool {
  44     attr::contains_name(attrs, "no_implicit_prelude")
  45 }
  46
  47 fn spanned<T>(x: T) -> codemap::Spanned<T> {
  48     codemap::Spanned {
  49         node: x,
  50         span: dummy_sp(),
  51     }
  52 }
  53
  54 struct StandardLibraryInjector {
  55     sess: Session,
  56 }
  57
  58 impl fold::ast_fold for StandardLibraryInjector {
  59     fn fold_crate(&mut self, crate: ast::Crate) -> ast::Crate {
  60         let mut vis = ~[ast::view_item {
  61             node: ast::view_item_extern_mod(self.sess.ident_of("std"),
  62                                             Some((format!("std\\#{}", VERSION).to_managed(),
  63                                                   ast::CookedStr)),
  64                                             ast::DUMMY_NODE_ID),
  65             attrs: ~[],
  66             vis: ast::private,
  67             span: dummy_sp()
  68         }];
  69
  70         if use_uv(&crate) && !self.sess.building_library.get() {
  71             vis.push(ast::view_item {
  72                 node: ast::view_item_extern_mod(self.sess.ident_of("green"),
  73                                                 Some((format!("green\\#{}", VERSION).to_managed(),
  74                                                       ast::CookedStr)),
  75                                                 ast::DUMMY_NODE_ID),
  76                 attrs: ~[],
  77                 vis: ast::private,
  78                 span: dummy_sp()
  79             });
  80             vis.push(ast::view_item {
  81                 node: ast::view_item_extern_mod(self.sess.ident_of("rustuv"),
  82                                                 Some((format!("rustuv\\#{}", VERSION).to_managed(),
  83                                                       ast::CookedStr)),
  84                                                 ast::DUMMY_NODE_ID),
  85                 attrs: ~[],
  86                 vis: ast::private,
  87                 span: dummy_sp()
  88             });
  89         }
  90
  91         vis.push_all(crate.module.view_items);
  92         let mut new_module = ast::_mod {
  93             view_items: vis,
  94             ..crate.module.clone()
  95         };
  96
  97         if !no_prelude(crate.attrs) {
  98             // only add `use std::prelude::*;` if there wasn't a
  99             // `#[no_implicit_prelude];` at the crate level.
 100             new_module = self.fold_mod(&new_module);
 101         }
 102
 103         ast::Crate {
 104             module: new_module,
 105             ..crate
 106         }
 107     }
 108
 109     fn fold_item(&mut self, item: @ast::item) -> SmallVector<@ast::item> {
 110         if !no_prelude(item.attrs) {
 111             // only recur if there wasn't `#[no_implicit_prelude];`
 112             // on this item, i.e. this means that the prelude is not
 113             // implicitly imported though the whole subtree
 114             fold::noop_fold_item(item, self)
 115         } else {
 116             SmallVector::one(item)
 117         }
 118     }
 119
 120     fn fold_mod(&mut self, module: &ast::_mod) -> ast::_mod {
 121         let prelude_path = ast::Path {
 122             span: dummy_sp(),
 123             global: false,
 124             segments: ~[
 125                 ast::PathSegment {
 126                     identifier: self.sess.ident_of("std"),
 127                     lifetimes: opt_vec::Empty,
 128                     types: opt_vec::Empty,
 129                 },
 130                 ast::PathSegment {
 131                     identifier: self.sess.ident_of("prelude"),
 132                     lifetimes: opt_vec::Empty,
 133                     types: opt_vec::Empty,
 134                 },
 135             ],
 136         };
 137
 138         let vp = @spanned(ast::view_path_glob(prelude_path,
 139                                               ast::DUMMY_NODE_ID));
 140         let vi2 = ast::view_item {
 141             node: ast::view_item_use(~[vp]),
 142             attrs: ~[],
 143             vis: ast::private,
 144             span: dummy_sp(),
 145         };
 146
 147         let vis = vec::append(~[vi2], module.view_items);
 148
 149         // FIXME #2543: Bad copy.
 150         let new_module = ast::_mod {
 151             view_items: vis,
 152             ..(*module).clone()
 153         };
 154         fold::noop_fold_mod(&new_module, self)
 155     }
 156 }
 157
 158 fn inject_libstd_ref(sess: Session, crate: ast::Crate) -> ast::Crate {
 159     let mut fold = StandardLibraryInjector {
 160         sess: sess,
 161     };
 162     fold.fold_crate(crate)
 163 }