2013-08-01 08:03:03 -05:00
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// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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/**
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The compiler code necessary to support the cfg! extension, which
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expands to a literal `true` or `false` based on whether the given cfgs
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match the current compilation environment.
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*/
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use ast;
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2013-08-31 11:13:04 -05:00
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use codemap::Span;
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2013-08-01 08:03:03 -05:00
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use ext::base::*;
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use ext::base;
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use ext::build::AstBuilder;
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use attr;
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use attr::*;
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use parse;
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use parse::token;
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use parse::attr::parser_attr;
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2013-08-31 11:13:04 -05:00
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pub fn expand_cfg(cx: @ExtCtxt, sp: Span, tts: &[ast::token_tree]) -> base::MacResult {
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2013-08-01 08:03:03 -05:00
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let p = parse::new_parser_from_tts(cx.parse_sess(), cx.cfg(), tts.to_owned());
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let mut cfgs = ~[];
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// parse `cfg!(meta_item, meta_item(x,y), meta_item="foo", ...)`
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while *p.token != token::EOF {
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cfgs.push(p.parse_meta_item());
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if p.eat(&token::EOF) { break } // trailing comma is optional,.
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p.expect(&token::COMMA);
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}
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// test_cfg searches for meta items looking like `cfg(foo, ...)`
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let in_cfg = &[cx.meta_list(sp, @"cfg", cfgs)];
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2013-08-09 22:09:47 -05:00
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let matches_cfg = attr::test_cfg(cx.cfg(), in_cfg.iter().map(|&x| x));
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2013-08-01 08:03:03 -05:00
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let e = cx.expr_bool(sp, matches_cfg);
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MRExpr(e)
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}
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