bjoernager/rust
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Add new syntax for patterns that match the head constructor only

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Adds a new kind of pattern C(*) where C is a constructor that may
have any number of fields. This pattern matches any value
constructed with C, without binding names for any of the fields.

Closes #1701.
This commit is contained in:
Tim Chevalier 2012-04-20 00:54:42 -07:00
parent 087b12ac29
commit 37b0549730
12 changed files with 105 additions and 44 deletions
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32
src/librustsyntax/parse/parser.rs
View file

@ -1417,24 +1417,38 @@ fn parse_pat(p: parser) -> @ast::pat {
} else {
let enum_path = parse_path_and_ty_param_substs(p, true);
hi = enum_path.span.hi;
let mut args: [@ast::pat];
let mut args: [@ast::pat] = [];
let mut star_pat = false;
alt p.token {
token::LPAREN {
let a =
parse_seq(token::LPAREN, token::RPAREN,
seq_sep(token::COMMA), parse_pat, p);
args = a.node;
hi = a.span.hi;
alt p.look_ahead(1u) {
token::BINOP(token::STAR) {
// This is a "top constructor only" pat
p.bump(); p.bump();
star_pat = true;
expect(p, token::RPAREN);
}
_ {
let a =
parse_seq(token::LPAREN, token::RPAREN,
seq_sep(token::COMMA), parse_pat, p);
args = a.node;
hi = a.span.hi;
}
}
}
_ { args = []; }
_ { }
}
// at this point, we're not sure whether it's a enum or a bind
if vec::len(args) == 0u &&
if star_pat {
pat = ast::pat_enum(enum_path, none);
}
else if vec::is_empty(args) &&
vec::len(enum_path.node.idents) == 1u {
pat = ast::pat_ident(enum_path, none);
}
else {
pat = ast::pat_enum(enum_path, args);
pat = ast::pat_enum(enum_path, some(args));
}
}
}