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
  23 static STD_VERSION: &'static str = "0.9-pre";
  24
  25 pub fn maybe_inject_libstd_ref(sess: Session, crate: ast::Crate)
  26                                -> ast::Crate {
  27     if use_std(&crate) {
  28         inject_libstd_ref(sess, crate)
  29     } else {
  30         crate
  31     }
  32 }
  33
  34 fn use_std(crate: &ast::Crate) -> bool {
  35     !attr::contains_name(crate.attrs, "no_std")
  36 }
  37
  38 fn use_uv(crate: &ast::Crate) -> bool {
  39     !attr::contains_name(crate.attrs, "no_uv")
  40 }
  41
  42 fn no_prelude(attrs: &[ast::Attribute]) -> bool {
  43     attr::contains_name(attrs, "no_implicit_prelude")
  44 }
  45
  46 fn spanned<T>(x: T) -> codemap::Spanned<T> {
  47     codemap::Spanned {
  48         node: x,
  49         span: dummy_sp(),
  50     }
  51 }
  52
  53 struct StandardLibraryInjector {
  54     sess: Session,
  55 }
  56
  57 impl fold::ast_fold for StandardLibraryInjector {
  58     fn fold_crate(&self, crate: ast::Crate) -> ast::Crate {
  59         let version = STD_VERSION.to_managed();
  60         let vers_item = attr::mk_name_value_item_str(@"vers", version);
  61         let mut vis = ~[ast::view_item {
  62             node: ast::view_item_extern_mod(self.sess.ident_of("std"),
  63                                             None,
  64                                             ~[vers_item.clone()],
  65                                             ast::DUMMY_NODE_ID),
  66             attrs: ~[],
  67             vis: ast::private,
  68             span: dummy_sp()
  69         }];
  70
  71         if use_uv(&crate) && !*self.sess.building_library {
  72             vis.push(ast::view_item {
  73                 node: ast::view_item_extern_mod(self.sess.ident_of("rustuv"),
  74                                                 None,
  75                                                 ~[vers_item],
  76                                                 ast::DUMMY_NODE_ID),
  77                 attrs: ~[],
  78                 vis: ast::private,
  79                 span: dummy_sp()
  80             });
  81         }
  82
  83         vis.push_all(crate.module.view_items);
  84         let mut new_module = ast::_mod {
  85             view_items: vis,
  86             ..crate.module.clone()
  87         };
  88
  89         if !no_prelude(crate.attrs) {
  90             // only add `use std::prelude::*;` if there wasn't a
  91             // `#[no_implicit_prelude];` at the crate level.
  92             new_module = self.fold_mod(&new_module);
  93         }
  94
  95         ast::Crate {
  96             module: new_module,
  97             ..crate
  98         }
  99     }
 100
 101     fn fold_item(&self, item: @ast::item) -> Option<@ast::item> {
 102         if !no_prelude(item.attrs) {
 103             // only recur if there wasn't `#[no_implicit_prelude];`
 104             // on this item, i.e. this means that the prelude is not
 105             // implicitly imported though the whole subtree
 106             fold::noop_fold_item(item, self)
 107         } else {
 108             Some(item)
 109         }
 110     }
 111
 112     fn fold_mod(&self, module: &ast::_mod) -> ast::_mod {
 113         let prelude_path = ast::Path {
 114             span: dummy_sp(),
 115             global: false,
 116             segments: ~[
 117                 ast::PathSegment {
 118                     identifier: self.sess.ident_of("std"),
 119                     lifetime: None,
 120                     types: opt_vec::Empty,
 121                 },
 122                 ast::PathSegment {
 123                     identifier: self.sess.ident_of("prelude"),
 124                     lifetime: None,
 125                     types: opt_vec::Empty,
 126                 },
 127             ],
 128         };
 129
 130         let vp = @spanned(ast::view_path_glob(prelude_path,
 131                                               ast::DUMMY_NODE_ID));
 132         let vi2 = ast::view_item {
 133             node: ast::view_item_use(~[vp]),
 134             attrs: ~[],
 135             vis: ast::private,
 136             span: dummy_sp(),
 137         };
 138
 139         let vis = vec::append(~[vi2], module.view_items);
 140
 141         // FIXME #2543: Bad copy.
 142         let new_module = ast::_mod {
 143             view_items: vis,
 144             ..(*module).clone()
 145         };
 146         fold::noop_fold_mod(&new_module, self)
 147     }
 148 }
 149
 150 fn inject_libstd_ref(sess: Session, crate: ast::Crate) -> ast::Crate {
 151     let fold = StandardLibraryInjector {
 152         sess: sess,
 153     };
 154     fold.fold_crate(crate)
 155 }