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