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auto merge of #13079 : alexcrichton/rust/colons, r=cmr

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The previous syntax was `Foo:Bound<trait-parameters>`, but this is a little
ambiguous because it was being parsed as `Foo: (Bound<trait-parameters)` rather
than `Foo: (Bound) <trait-parameters>`

This commit changes the syntax to `Foo<trait-parameters>: Bound` in order to be
clear where the trait parameters are going.

Closes #9265
This commit is contained in:
bors 2014-03-26 19:32:01 -07:00
commit c329a17461
7 changed files with 59 additions and 73 deletions
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73
src/libsyntax/parse/parser.rs
View file

@ -111,13 +111,6 @@ pub enum PathParsingMode {
LifetimeAndTypesAndBounds,
}
/// A pair of a path segment and group of type parameter bounds. (See `ast.rs`
/// for the definition of a path segment.)
struct PathSegmentAndBoundSet {
segment: ast::PathSegment,
bound_set: Option<OwnedSlice<TyParamBound>>,
}
/// A path paired with optional type bounds.
pub struct PathAndBounds {
path: ast::Path,
@ -1514,24 +1507,14 @@ impl<'a> Parser<'a> {
// First, parse an identifier.
let identifier = self.parse_ident();
// Next, parse a colon and bounded type parameters, if applicable.
let bound_set = if mode == LifetimeAndTypesAndBounds {
self.parse_optional_ty_param_bounds()
} else {
None
};
// Parse the '::' before type parameters if it's required. If
// it is required and wasn't present, then we're done.
if mode == LifetimeAndTypesWithColons &&
!self.eat(&token::MOD_SEP) {
segments.push(PathSegmentAndBoundSet {
segment: ast::PathSegment {
identifier: identifier,
lifetimes: Vec::new(),
types: OwnedSlice::empty(),
},
bound_set: bound_set
segments.push(ast::PathSegment {
identifier: identifier,
lifetimes: Vec::new(),
types: OwnedSlice::empty(),
});
break
}
@ -1548,13 +1531,10 @@ impl<'a> Parser<'a> {
};
// Assemble and push the result.
segments.push(PathSegmentAndBoundSet {
segment: ast::PathSegment {
identifier: identifier,
lifetimes: lifetimes,
types: types,
},
bound_set: bound_set
segments.push(ast::PathSegment {
identifier: identifier,
lifetimes: lifetimes,
types: types,
});
// We're done if we don't see a '::', unless the mode required
@ -1567,42 +1547,25 @@ impl<'a> Parser<'a> {
}
}
// Next, parse a colon and bounded type parameters, if applicable.
let bounds = if mode == LifetimeAndTypesAndBounds {
self.parse_optional_ty_param_bounds()
} else {
None
};
// Assemble the span.
let span = mk_sp(lo, self.last_span.hi);
// Assemble the path segments.
let mut path_segments = Vec::new();
let mut bounds = None;
let last_segment_index = segments.len() - 1;
for (i, segment_and_bounds) in segments.move_iter().enumerate() {
let PathSegmentAndBoundSet {
segment: segment,
bound_set: bound_set
} = segment_and_bounds;
path_segments.push(segment);
if bound_set.is_some() {
if i != last_segment_index {
self.span_err(span,
"type parameter bounds are allowed only \
before the last segment in a path")
}
bounds = bound_set
}
}
// Assemble the result.
let path_and_bounds = PathAndBounds {
PathAndBounds {
path: ast::Path {
span: span,
global: is_global,
segments: path_segments,
segments: segments,
},
bounds: bounds,
};
path_and_bounds
}
}
/// parses 0 or 1 lifetime