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use ast;
use codemap::Span;
use ext::base::*;
use ext::base;
use ext::build::AstBuilder;
use attr;
use attr::*;
use parse::attr::ParserAttr;
use parse::token;
pub fn expand_cfg<'cx>(cx: &mut ExtCtxt,
sp: Span,
tts: &[ast::TokenTree])
-> Box<base::MacResult+'static> {
let mut p = cx.new_parser_from_tts(tts);
let cfg = p.parse_meta_item();
if !p.eat(&token::Eof) {
cx.span_err(sp, "expected 1 cfg-pattern");
return DummyResult::expr(sp);
}
let matches_cfg = attr::cfg_matches(&cx.parse_sess.span_diagnostic, &cx.cfg, &*cfg);
MacExpr::new(cx.expr_bool(sp, matches_cfg))
}