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use attr::HasAttrs;
use {ast, codemap};
use ext::base::ExtCtxt;
use ext::build::AstBuilder;
use symbol::Symbol;
use syntax_pos::Span;
pub fn collect_derives(cx: &mut ExtCtxt, attrs: &mut Vec<ast::Attribute>) -> Vec<(Symbol, Span)> {
let mut result = Vec::new();
attrs.retain(|attr| {
if attr.name() != "derive" {
return true;
}
if attr.value_str().is_some() {
cx.span_err(attr.span, "unexpected value in `derive`");
return false;
}
let traits = attr.meta_item_list().unwrap_or(&[]).to_owned();
if traits.is_empty() {
cx.span_warn(attr.span, "empty trait list in `derive`");
return false;
}
for titem in traits {
if titem.word().is_none() {
cx.span_err(titem.span, "malformed `derive` entry");
return false;
}
result.push((titem.name().unwrap(), titem.span));
}
true
});
result
}
fn allow_unstable(cx: &mut ExtCtxt, span: Span, attr_name: &str) -> Span {
Span {
expn_id: cx.codemap().record_expansion(codemap::ExpnInfo {
call_site: span,
callee: codemap::NameAndSpan {
format: codemap::MacroAttribute(Symbol::intern(attr_name)),
span: Some(span),
allow_internal_unstable: true,
},
}),
..span
}
}
pub fn add_derived_markers<T: HasAttrs>(cx: &mut ExtCtxt, traits: &[(Symbol, Span)], item: T) -> T {
let span = match traits.get(0) {
Some(&(_, span)) => span,
None => return item,
};
item.map_attrs(|mut attrs| {
if traits.iter().any(|&(name, _)| name == "PartialEq") &&
traits.iter().any(|&(name, _)| name == "Eq") {
let span = allow_unstable(cx, span, "derive(PartialEq, Eq)");
let meta = cx.meta_word(span, Symbol::intern("structural_match"));
attrs.push(cx.attribute(span, meta));
}
if traits.iter().any(|&(name, _)| name == "Copy") &&
traits.iter().any(|&(name, _)| name == "Clone") {
let span = allow_unstable(cx, span, "derive(Copy, Clone)");
let meta = cx.meta_word(span, Symbol::intern("rustc_copy_clone_marker"));
attrs.push(cx.attribute(span, meta));
}
attrs
})
}