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 no_prelude(attrs: &[ast::Attribute]) -> bool {
  39     attr::contains_name(attrs, "no_implicit_prelude")
  40 }
  41
  42 fn spanned<T>(x: T) -> codemap::Spanned<T> {
  43     codemap::Spanned {
  44         node: x,
  45         span: dummy_sp(),
  46     }
  47 }
  48
  49 struct StandardLibraryInjector {
  50     sess: Session,
  51 }
  52
  53 impl fold::ast_fold for StandardLibraryInjector {
  54     fn fold_crate(&self, crate: ast::Crate) -> ast::Crate {
  55         let version = STD_VERSION.to_managed();
  56         let vi1 = ast::view_item {
  57             node: ast::view_item_extern_mod(self.sess.ident_of("std"),
  58                                             None,
  59                                             ~[],
  60                                             ast::DUMMY_NODE_ID),
  61             attrs: ~[
  62                 attr::mk_attr(attr::mk_name_value_item_str(@"vers", version))
  63             ],
  64             vis: ast::private,
  65             span: dummy_sp()
  66         };
  67
  68         let vis = vec::append(~[vi1], crate.module.view_items);
  69         let mut new_module = ast::_mod {
  70             view_items: vis,
  71             ..crate.module.clone()
  72         };
  73
  74         if !no_prelude(crate.attrs) {
  75             // only add `use std::prelude::*;` if there wasn't a
  76             // `#[no_implicit_prelude];` at the crate level.
  77             new_module = self.fold_mod(&new_module);
  78         }
  79
  80         ast::Crate {
  81             module: new_module,
  82             ..crate
  83         }
  84     }
  85
  86     fn fold_item(&self, item: @ast::item) -> Option<@ast::item> {
  87         if !no_prelude(item.attrs) {
  88             // only recur if there wasn't `#[no_implicit_prelude];`
  89             // on this item, i.e. this means that the prelude is not
  90             // implicitly imported though the whole subtree
  91             fold::noop_fold_item(item, self)
  92         } else {
  93             Some(item)
  94         }
  95     }
  96
  97     fn fold_mod(&self, module: &ast::_mod) -> ast::_mod {
  98         let prelude_path = ast::Path {
  99             span: dummy_sp(),
 100             global: false,
 101             segments: ~[
 102                 ast::PathSegment {
 103                     identifier: self.sess.ident_of("std"),
 104                     lifetime: None,
 105                     types: opt_vec::Empty,
 106                 },
 107                 ast::PathSegment {
 108                     identifier: self.sess.ident_of("prelude"),
 109                     lifetime: None,
 110                     types: opt_vec::Empty,
 111                 },
 112             ],
 113         };
 114
 115         let vp = @spanned(ast::view_path_glob(prelude_path,
 116                                               ast::DUMMY_NODE_ID));
 117         let vi2 = ast::view_item {
 118             node: ast::view_item_use(~[vp]),
 119             attrs: ~[],
 120             vis: ast::private,
 121             span: dummy_sp(),
 122         };
 123
 124         let vis = vec::append(~[vi2], module.view_items);
 125
 126         // FIXME #2543: Bad copy.
 127         let new_module = ast::_mod {
 128             view_items: vis,
 129             ..(*module).clone()
 130         };
 131         fold::noop_fold_mod(&new_module, self)
 132     }
 133 }
 134
 135 fn inject_libstd_ref(sess: Session, crate: ast::Crate) -> ast::Crate {
 136     let fold = StandardLibraryInjector {
 137         sess: sess,
 138     };
 139     fold.fold_crate(crate)
 140 }