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Make syntax for impls less magical

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The trick of interpreting parameters to the iface type as parameters
to the impl was just too magical.

Issue #1227
This commit is contained in:
Marijn Haverbeke 2012-01-03 15:29:28 +01:00
parent e1dc40b271
commit 506a6ec38b
1 changed files with 18 additions and 23 deletions
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41
src/comp/syntax/parse/parser.rs
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@ -1850,34 +1850,29 @@ fn parse_item_iface(p: parser, attrs: [ast::attribute]) -> @ast::item {
ast::item_iface(tps, meths), attrs);
}
// Parses three variants (with the initial params always optional):
// impl <T: copy> of to_str for [T] { ... }
// impl name<T> of to_str for [T] { ... }
// impl name<T> for [T] { ... }
fn parse_item_impl(p: parser, attrs: [ast::attribute]) -> @ast::item {
let lo = p.get_last_lo_pos(), ident, tps, ifce;
let lo = p.get_last_lo_pos();
fn wrap_path(p: parser, pt: @ast::path) -> @ast::ty {
@{node: ast::ty_path(pt, p.get_id()), span: pt.span}
}
if eat_word(p, "of") {
let (ident, tps) = if !is_word(p, "of") {
if p.peek() == token::LT { (none, parse_ty_params(p)) }
else { (some(parse_ident(p)), parse_ty_params(p)) }
} else { (none, []) };
let ifce = if eat_word(p, "of") {
let path = parse_path_and_ty_param_substs(p, false);
tps = vec::map(path.node.types, {|tp|
alt tp.node {
ast::ty_path(pt, _) {
if vec::len(pt.node.idents) == 1u &&
vec::len(pt.node.types) == 0u {
ret {ident: pt.node.idents[0], id: p.get_id(),
bounds: @[]};
}
}
_ {}
}
p.fatal("only single-word, parameter-less types allowed here");
});
ident = path.node.idents[vec::len(path.node.idents)-1u];
ifce = some(wrap_path(p, path));
} else {
ident = parse_ident(p);
tps = parse_ty_params(p);
ifce = if eat_word(p, "of") {
some(wrap_path(p, parse_path_and_ty_param_substs(p, false)))
} else { none };
if option::is_none(ident) {
ident = some(path.node.idents[vec::len(path.node.idents) - 1u]);
}
some(wrap_path(p, path))
} else { none };
let ident = alt ident {
some(name) { name }
none. { expect_word(p, "of"); fail; }
};
expect_word(p, "for");
let ty = parse_ty(p, false), meths = [];