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 static STD_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(&self, crate: ast::Crate) -> ast::Crate {
  60         let version = STD_VERSION.to_managed();
  61         let vers_item = attr::mk_name_value_item_str(@"vers", version);
  62         let mut vis = ~[ast::view_item {
  63             node: ast::view_item_extern_mod(self.sess.ident_of("std"),
  64                                             None,
  65                                             ~[vers_item.clone()],
  66                                             ast::DUMMY_NODE_ID),
  67             attrs: ~[],
  68             vis: ast::private,
  69             span: dummy_sp()
  70         }];
  71
  72         if use_uv(&crate) && !*self.sess.building_library {
  73             vis.push(ast::view_item {
  74                 node: ast::view_item_extern_mod(self.sess.ident_of("rustuv"),
  75                                                 None,
  76                                                 ~[vers_item],
  77                                                 ast::DUMMY_NODE_ID),
  78                 attrs: ~[],
  79                 vis: ast::private,
  80                 span: dummy_sp()
  81             });
  82         }
  83
  84         vis.push_all(crate.module.view_items);
  85         let mut new_module = ast::_mod {
  86             view_items: vis,
  87             ..crate.module.clone()
  88         };
  89
  90         if !no_prelude(crate.attrs) {
  91             // only add `use std::prelude::*;` if there wasn't a
  92             // `#[no_implicit_prelude];` at the crate level.
  93             new_module = self.fold_mod(&new_module);
  94         }
  95
  96         ast::Crate {
  97             module: new_module,
  98             ..crate
  99         }
 100     }
 101
 102     fn fold_item(&self, item: @ast::item) -> SmallVector<@ast::item> {
 103         if !no_prelude(item.attrs) {
 104             // only recur if there wasn't `#[no_implicit_prelude];`
 105             // on this item, i.e. this means that the prelude is not
 106             // implicitly imported though the whole subtree
 107             fold::noop_fold_item(item, self)
 108         } else {
 109             SmallVector::one(item)
 110         }
 111     }
 112
 113     fn fold_mod(&self, module: &ast::_mod) -> ast::_mod {
 114         let prelude_path = ast::Path {
 115             span: dummy_sp(),
 116             global: false,
 117             segments: ~[
 118                 ast::PathSegment {
 119                     identifier: self.sess.ident_of("std"),
 120                     lifetimes: opt_vec::Empty,
 121                     types: opt_vec::Empty,
 122                 },
 123                 ast::PathSegment {
 124                     identifier: self.sess.ident_of("prelude"),
 125                     lifetimes: opt_vec::Empty,
 126                     types: opt_vec::Empty,
 127                 },
 128             ],
 129         };
 130
 131         let vp = @spanned(ast::view_path_glob(prelude_path,
 132                                               ast::DUMMY_NODE_ID));
 133         let vi2 = ast::view_item {
 134             node: ast::view_item_use(~[vp]),
 135             attrs: ~[],
 136             vis: ast::private,
 137             span: dummy_sp(),
 138         };
 139
 140         let vis = vec::append(~[vi2], module.view_items);
 141
 142         // FIXME #2543: Bad copy.
 143         let new_module = ast::_mod {
 144             view_items: vis,
 145             ..(*module).clone()
 146         };
 147         fold::noop_fold_mod(&new_module, self)
 148     }
 149 }
 150
 151 fn inject_libstd_ref(sess: Session, crate: ast::Crate) -> ast::Crate {
 152     let fold = StandardLibraryInjector {
 153         sess: sess,
 154     };
 155     fold.fold_crate(crate)
 156 }