60 lines
2.0 KiB
Rust
60 lines
2.0 KiB
Rust
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// Copyright 2014 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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use std::gc::{Gc, GC};
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use ast;
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use attr;
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use codemap::Span;
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use ext::base::ExtCtxt;
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use ext::build::AstBuilder;
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pub fn expand(cx: &mut ExtCtxt, sp: Span, mi: Gc<ast::MetaItem>, it: Gc<ast::Item>)
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-> Gc<ast::Item> {
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let (cfg, attr) = match mi.node {
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ast::MetaList(_, ref mis) if mis.len() == 2 => (mis[0], mis[1]),
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_ => {
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cx.span_err(sp, "expected `#[cfg_attr(<cfg pattern>, <attr>)]`");
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return it;
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}
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};
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let mut out = (*it).clone();
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if cfg_matches(cx, cfg) {
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out.attrs.push(cx.attribute(attr.span, attr));
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}
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box(GC) out
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}
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fn cfg_matches(cx: &mut ExtCtxt, cfg: Gc<ast::MetaItem>) -> bool {
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match cfg.node {
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ast::MetaList(ref pred, ref mis) if pred.get() == "any" =>
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mis.iter().any(|mi| cfg_matches(cx, *mi)),
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ast::MetaList(ref pred, ref mis) if pred.get() == "all" =>
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mis.iter().all(|mi| cfg_matches(cx, *mi)),
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ast::MetaList(ref pred, ref mis) if pred.get() == "not" => {
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if mis.len() != 1 {
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cx.span_err(cfg.span, format!("expected 1 value, got {}",
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mis.len()).as_slice());
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return false;
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}
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!cfg_matches(cx, mis[0])
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}
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ast::MetaList(ref pred, _) => {
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cx.span_err(cfg.span,
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format!("invalid predicate `{}`", pred).as_slice());
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false
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},
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ast::MetaWord(_) | ast::MetaNameValue(..) =>
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attr::contains(cx.cfg.as_slice(), cfg),
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}
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}
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