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1 | // Copyright 2013 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 | /// The compiler code necessary to support the cfg! extension, which expands to | |
12 | /// a literal `true` or `false` based on whether the given cfg matches the | |
13 | /// current compilation environment. | |
14 | ||
15 | use ast; | |
16 | use codemap::Span; | |
17 | use ext::base::*; | |
18 | use ext::base; | |
19 | use ext::build::AstBuilder; | |
20 | use attr; | |
21 | use attr::*; | |
1a4d82fc | 22 | use parse::token; |
92a42be0 | 23 | use config::CfgDiagReal; |
1a4d82fc JJ |
24 | |
25 | pub fn expand_cfg<'cx>(cx: &mut ExtCtxt, | |
26 | sp: Span, | |
27 | tts: &[ast::TokenTree]) | |
28 | -> Box<base::MacResult+'static> { | |
29 | let mut p = cx.new_parser_from_tts(tts); | |
92a42be0 | 30 | let cfg = panictry!(p.parse_meta_item()); |
1a4d82fc | 31 | |
9346a6ac | 32 | if !panictry!(p.eat(&token::Eof)){ |
1a4d82fc JJ |
33 | cx.span_err(sp, "expected 1 cfg-pattern"); |
34 | return DummyResult::expr(sp); | |
35 | } | |
36 | ||
92a42be0 SL |
37 | let matches_cfg = { |
38 | let mut diag = CfgDiagReal { | |
39 | diag: &cx.parse_sess.span_diagnostic, | |
40 | feature_gated_cfgs: cx.feature_gated_cfgs, | |
41 | }; | |
42 | attr::cfg_matches(&cx.cfg, &cfg, &mut diag) | |
43 | }; | |
c34b1796 | 44 | MacEager::expr(cx.expr_bool(sp, matches_cfg)) |
1a4d82fc | 45 | } |