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 ext::hygiene::{Mark, SyntaxContext};
  14 use symbol::{Symbol, keywords};
  15 use syntax_pos::{DUMMY_SP, Span};
  16 use codemap::{self, ExpnInfo, NameAndSpan, MacroAttribute};
  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(sp: Span) -> Span {
  24     let mark = Mark::fresh(Mark::root());
  25     mark.set_expn_info(ExpnInfo {
  26         call_site: DUMMY_SP,
  27         callee: NameAndSpan {
  28             format: MacroAttribute(Symbol::intern("std_inject")),
  29             span: None,
  30             allow_internal_unstable: true,
  31         }
  32     });
  33     Span { ctxt: SyntaxContext::empty().apply_mark(mark), ..sp }
  34 }
  35
  36 pub fn injected_crate_name(krate: &ast::Crate) -> Option<&'static str> {
  37     if attr::contains_name(&krate.attrs, "no_core") {
  38         None
  39     } else if attr::contains_name(&krate.attrs, "no_std") {
  40         Some("core")
  41     } else {
  42         Some("std")
  43     }
  44 }
  45
  46 pub fn maybe_inject_crates_ref(mut krate: ast::Crate, alt_std_name: Option<String>) -> ast::Crate {
  47     let name = match injected_crate_name(&krate) {
  48         Some(name) => name,
  49         None => return krate,
  50     };
  51
  52     let crate_name = Symbol::intern(&alt_std_name.unwrap_or_else(|| name.to_string()));
  53
  54     krate.module.items.insert(0, P(ast::Item {
  55         attrs: vec![attr::mk_attr_outer(DUMMY_SP,
  56                                         attr::mk_attr_id(),
  57                                         attr::mk_word_item(Symbol::intern("macro_use")))],
  58         vis: ast::Visibility::Inherited,
  59         node: ast::ItemKind::ExternCrate(Some(crate_name)),
  60         ident: ast::Ident::from_str(name),
  61         id: ast::DUMMY_NODE_ID,
  62         span: DUMMY_SP,
  63     }));
  64
  65     let span = ignored_span(DUMMY_SP);
  66     krate.module.items.insert(0, P(ast::Item {
  67         attrs: vec![ast::Attribute {
  68             style: ast::AttrStyle::Outer,
  69             path: ast::Path::from_ident(span, ast::Ident::from_str("prelude_import")),
  70             tokens: TokenStream::empty(),
  71             id: attr::mk_attr_id(),
  72             is_sugared_doc: false,
  73             span: span,
  74         }],
  75         vis: ast::Visibility::Inherited,
  76         node: ast::ItemKind::Use(P(codemap::dummy_spanned(ast::ViewPathGlob(ast::Path {
  77             segments: ["{{root}}", name, "prelude", "v1"].into_iter().map(|name| {
  78                 ast::PathSegment::from_ident(ast::Ident::from_str(name), DUMMY_SP)
  79             }).collect(),
  80             span: span,
  81         })))),
  82         id: ast::DUMMY_NODE_ID,
  83         ident: keywords::Invalid.ident(),
  84         span: span,
  85     }));
  86
  87     krate
  88 }