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<'a> {
  49     alt_std_name: Option<String>
  50 }
  51
  52 impl<'a> fold::Folder for StandardLibraryInjector<'a> {
  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<'a>;
  84
  85 impl<'a> fold::Folder for PreludeInjector<'a> {
  86     fn fold_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
  87         // only add `use std::prelude::*;` if there wasn't a
  88         // `#![no_implicit_prelude]` at the crate level.
  89         // fold_mod() will insert glob path.
  90         if !no_prelude(&krate.attrs[]) {
  91             krate.module = self.fold_mod(krate.module);
  92         }
  93         krate
  94     }
  95
  96     fn fold_item(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
  97         if !no_prelude(&item.attrs[]) {
  98             // only recur if there wasn't `#![no_implicit_prelude]`
  99             // on this item, i.e. this means that the prelude is not
 100             // implicitly imported though the whole subtree
 101             fold::noop_fold_item(item, self)
 102         } else {
 103             SmallVector::one(item)
 104         }
 105     }
 106
 107     fn fold_mod(&mut self, mut mod_: ast::Mod) -> ast::Mod {
 108         let prelude_path = ast::Path {
 109             span: DUMMY_SP,
 110             global: false,
 111             segments: vec![
 112                 ast::PathSegment {
 113                     identifier: token::str_to_ident("std"),
 114                     parameters: ast::PathParameters::none(),
 115                 },
 116                 ast::PathSegment {
 117                     identifier: token::str_to_ident("prelude"),
 118                     parameters: ast::PathParameters::none(),
 119                 },
 120                 ast::PathSegment {
 121                     identifier: token::str_to_ident("v1"),
 122                     parameters: ast::PathParameters::none(),
 123                 },
 124             ],
 125         };
 126
 127         let vp = P(codemap::dummy_spanned(ast::ViewPathGlob(prelude_path)));
 128         mod_.items.insert(0, P(ast::Item {
 129             id: ast::DUMMY_NODE_ID,
 130             ident: special_idents::invalid,
 131             node: ast::ItemUse(vp),
 132             attrs: vec![ast::Attribute {
 133                 span: DUMMY_SP,
 134                 node: ast::Attribute_ {
 135                     id: attr::mk_attr_id(),
 136                     style: ast::AttrOuter,
 137                     value: P(ast::MetaItem {
 138                         span: DUMMY_SP,
 139                         node: ast::MetaWord(token::get_name(
 140                                 special_idents::prelude_import.name)),
 141                     }),
 142                     is_sugared_doc: false,
 143                 },
 144             }],
 145             vis: ast::Inherited,
 146             span: DUMMY_SP,
 147         }));
 148
 149         fold::noop_fold_mod(mod_, self)
 150     }
 151 }
 152
 153 fn inject_prelude(krate: ast::Crate) -> ast::Crate {
 154     let mut fold = PreludeInjector;
 155     fold.fold_crate(krate)
 156 }