src/libsyntax/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 use ast;
  12 use attr;
  13 use codemap::DUMMY_SP;
  14 use codemap;
  15 use fold::Folder;
  16 use fold;
  17 use parse::token::InternedString;
  18 use parse::token::special_idents;
  19 use parse::token;
  20 use ptr::P;
  21 use util::small_vector::SmallVector;
  22
  23 pub fn maybe_inject_crates_ref(krate: ast::Crate, alt_std_name: Option<String>)
  24                                -> ast::Crate {
  25     if use_std(&krate) {
  26         inject_crates_ref(krate, alt_std_name)
  27     } else {
  28         krate
  29     }
  30 }
  31
  32 pub fn maybe_inject_prelude(krate: ast::Crate) -> ast::Crate {
  33     if use_std(&krate) {
  34         inject_prelude(krate)
  35     } else {
  36         krate
  37     }
  38 }
  39
  40 pub fn use_std(krate: &ast::Crate) -> bool {
  41     !attr::contains_name(&krate.attrs[], "no_std")
  42 }
  43
  44 fn no_prelude(attrs: &[ast::Attribute]) -> bool {
  45     attr::contains_name(attrs, "no_implicit_prelude")
  46 }
  47
  48 struct StandardLibraryInjector {
  49     alt_std_name: Option<String>,
  50 }
  51
  52 impl fold::Folder for StandardLibraryInjector {
  53     fn fold_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
  54
  55         // The name to use in `extern crate "name" as std;`
  56         let actual_crate_name = match self.alt_std_name {
  57             Some(ref s) => token::intern_and_get_ident(&s[..]),
  58             None => token::intern_and_get_ident("std"),
  59         };
  60
  61         krate.module.items.insert(0, P(ast::Item {
  62             id: ast::DUMMY_NODE_ID,
  63             ident: token::str_to_ident("std"),
  64             attrs: vec!(
  65                 attr::mk_attr_outer(attr::mk_attr_id(), attr::mk_word_item(
  66                         InternedString::new("macro_use")))),
  67             node: ast::ItemExternCrate(Some((actual_crate_name, ast::CookedStr))),
  68             vis: ast::Inherited,
  69             span: DUMMY_SP
  70         }));
  71
  72         krate
  73     }
  74 }
  75
  76 fn inject_crates_ref(krate: ast::Crate, alt_std_name: Option<String>) -> ast::Crate {
  77     let mut fold = StandardLibraryInjector {
  78         alt_std_name: alt_std_name
  79     };
  80     fold.fold_crate(krate)
  81 }
  82
  83 struct PreludeInjector;
  84
  85
  86 impl fold::Folder for PreludeInjector {
  87     fn fold_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
  88         // only add `use std::prelude::*;` if there wasn't a
  89         // `#![no_implicit_prelude]` at the crate level.
  90         // fold_mod() will insert glob path.
  91         if !no_prelude(&krate.attrs[]) {
  92             krate.module = self.fold_mod(krate.module);
  93         }
  94         krate
  95     }
  96
  97     fn fold_item(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
  98         if !no_prelude(&item.attrs[]) {
  99             // only recur if there wasn't `#![no_implicit_prelude]`
 100             // on this item, i.e. this means that the prelude is not
 101             // implicitly imported though the whole subtree
 102             fold::noop_fold_item(item, self)
 103         } else {
 104             SmallVector::one(item)
 105         }
 106     }
 107
 108     fn fold_mod(&mut self, mut mod_: ast::Mod) -> ast::Mod {
 109         let prelude_path = ast::Path {
 110             span: DUMMY_SP,
 111             global: false,
 112             segments: vec![
 113                 ast::PathSegment {
 114                     identifier: token::str_to_ident("std"),
 115                     parameters: ast::PathParameters::none(),
 116                 },
 117                 ast::PathSegment {
 118                     identifier: token::str_to_ident("prelude"),
 119                     parameters: ast::PathParameters::none(),
 120                 },
 121                 ast::PathSegment {
 122                     identifier: token::str_to_ident("v1"),
 123                     parameters: ast::PathParameters::none(),
 124                 },
 125             ],
 126         };
 127
 128         let vp = P(codemap::dummy_spanned(ast::ViewPathGlob(prelude_path)));
 129         mod_.items.insert(0, P(ast::Item {
 130             id: ast::DUMMY_NODE_ID,
 131             ident: special_idents::invalid,
 132             node: ast::ItemUse(vp),
 133             attrs: vec![ast::Attribute {
 134                 span: DUMMY_SP,
 135                 node: ast::Attribute_ {
 136                     id: attr::mk_attr_id(),
 137                     style: ast::AttrOuter,
 138                     value: P(ast::MetaItem {
 139                         span: DUMMY_SP,
 140                         node: ast::MetaWord(token::get_name(
 141                                 special_idents::prelude_import.name)),
 142                     }),
 143                     is_sugared_doc: false,
 144                 },
 145             }],
 146             vis: ast::Inherited,
 147             span: DUMMY_SP,
 148         }));
 149
 150         fold::noop_fold_mod(mod_, self)
 151     }
 152 }
 153
 154 fn inject_prelude(krate: ast::Crate) -> ast::Crate {
 155     let mut fold = PreludeInjector;
 156     fold.fold_crate(krate)
 157 }