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 symbol::{Symbol, keywords};
  14 use syntax_pos::{DUMMY_SP, Span};
  15 use codemap::{self, ExpnInfo, NameAndSpan, MacroAttribute};
  16 use parse::ParseSess;
  17 use ptr::P;
  18
  19 /// Craft a span that will be ignored by the stability lint's
  20 /// call to codemap's is_internal check.
  21 /// The expanded code uses the unstable `#[prelude_import]` attribute.
  22 fn ignored_span(sess: &ParseSess, sp: Span) -> Span {
  23     let info = ExpnInfo {
  24         call_site: DUMMY_SP,
  25         callee: NameAndSpan {
  26             format: MacroAttribute(Symbol::intern("std_inject")),
  27             span: None,
  28             allow_internal_unstable: true,
  29         }
  30     };
  31     let expn_id = sess.codemap().record_expansion(info);
  32     let mut sp = sp;
  33     sp.expn_id = expn_id;
  34     return sp;
  35 }
  36
  37 pub fn injected_crate_name(krate: &ast::Crate) -> Option<&'static str> {
  38     if attr::contains_name(&krate.attrs, "no_core") {
  39         None
  40     } else if attr::contains_name(&krate.attrs, "no_std") {
  41         Some("core")
  42     } else {
  43         Some("std")
  44     }
  45 }
  46
  47 pub fn maybe_inject_crates_ref(sess: &ParseSess,
  48                                mut krate: ast::Crate,
  49                                alt_std_name: Option<String>)
  50                                -> ast::Crate {
  51     let name = match injected_crate_name(&krate) {
  52         Some(name) => name,
  53         None => return krate,
  54     };
  55
  56     let crate_name = Symbol::intern(&alt_std_name.unwrap_or(name.to_string()));
  57
  58     krate.module.items.insert(0, P(ast::Item {
  59         attrs: vec![attr::mk_attr_outer(attr::mk_attr_id(),
  60                                         attr::mk_word_item(Symbol::intern("macro_use")))],
  61         vis: ast::Visibility::Inherited,
  62         node: ast::ItemKind::ExternCrate(Some(crate_name)),
  63         ident: ast::Ident::from_str(name),
  64         id: ast::DUMMY_NODE_ID,
  65         span: DUMMY_SP,
  66     }));
  67
  68     let span = ignored_span(sess, DUMMY_SP);
  69     krate.module.items.insert(0, P(ast::Item {
  70         attrs: vec![ast::Attribute {
  71             style: ast::AttrStyle::Outer,
  72             value: ast::MetaItem {
  73                 name: Symbol::intern("prelude_import"),
  74                 node: ast::MetaItemKind::Word,
  75                 span: span,
  76             },
  77             id: attr::mk_attr_id(),
  78             is_sugared_doc: false,
  79             span: span,
  80         }],
  81         vis: ast::Visibility::Inherited,
  82         node: ast::ItemKind::Use(P(codemap::dummy_spanned(ast::ViewPathGlob(ast::Path {
  83             global: false,
  84             segments: vec![name, "prelude", "v1"].into_iter().map(|name| ast::PathSegment {
  85                 identifier: ast::Ident::from_str(name),
  86                 parameters: ast::PathParameters::none(),
  87             }).collect(),
  88             span: span,
  89         })))),
  90         id: ast::DUMMY_NODE_ID,
  91         ident: keywords::Invalid.ident(),
  92         span: span,
  93     }));
  94
  95     krate
  96 }