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libsyntax: Implement the impl Trait for Type syntax

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Patrick Walton 2013-01-29 11:14:53 -08:00
parent 1b021d5868
commit 4ead38bae7
2 changed files with 49 additions and 6 deletions
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29
src/libsyntax/parse/parser.rs
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@ -2791,8 +2791,9 @@ impl Parser {
(ident, item_trait(tps, traits, meths), None)
}
// Parses four variants (with the region/type params always optional):
// Parses two variants (with the region/type params always optional):
// impl<T> ~[T] : to_str { ... }
// impl<T> to_str for ~[T] { ... }
fn parse_item_impl() -> item_info {
fn wrap_path(p: Parser, pt: @path) -> @Ty {
@Ty {
@ -2802,8 +2803,6 @@ impl Parser {
}
}
// We do two separate paths here: old-style impls and new-style impls.
// First, parse type parameters if necessary.
let mut tps;
if self.token == token::LT {
@ -2816,14 +2815,32 @@ impl Parser {
// XXX: clownshoes
let ident = special_idents::clownshoes_extensions;
// Parse the type.
let ty = self.parse_ty(false);
// Parse the type. (If this is `impl trait for type`, however, this
// actually parses the trait.)
let mut ty = self.parse_ty(false);
// Parse traits, if necessary.
let opt_trait = if self.token == token::COLON {
// Old-style trait.
self.bump();
Some(self.parse_trait_ref())
} else if self.eat_keyword(~"for") {
// New-style trait. Reinterpret the type as a trait.
let opt_trait_ref = match ty.node {
ty_path(path, node_id) => {
Some(@trait_ref {
path: path,
ref_id: node_id
})
}
_ => {
self.span_err(copy self.span, ~"not a trait");
None
}
};
ty = self.parse_ty(false);
opt_trait_ref
} else {
None
};