mirror of https://github.com/rust-lang/rust
36 lines
908 B
Rust
36 lines
908 B
Rust
//@ run-pass
|
|
// Test associated types appearing in struct-like enum variants.
|
|
|
|
|
|
use self::VarValue::*;
|
|
|
|
pub trait UnifyKey {
|
|
type Value;
|
|
fn to_index(&self) -> usize;
|
|
}
|
|
|
|
pub enum VarValue<K:UnifyKey> {
|
|
Redirect { to: K },
|
|
Root { value: K::Value, rank: usize },
|
|
}
|
|
|
|
fn get<'a,K:UnifyKey<Value=Option<V>>,V>(table: &'a Vec<VarValue<K>>, key: &K) -> &'a Option<V> {
|
|
match table[key.to_index()] {
|
|
VarValue::Redirect { to: ref k } => get(table, k),
|
|
VarValue::Root { value: ref v, rank: _ } => v,
|
|
}
|
|
}
|
|
|
|
impl UnifyKey for usize {
|
|
type Value = Option<char>;
|
|
fn to_index(&self) -> usize { *self }
|
|
}
|
|
|
|
fn main() {
|
|
let table = vec![/* 0 */ Redirect { to: 1 },
|
|
/* 1 */ Redirect { to: 3 },
|
|
/* 2 */ Root { value: Some('x'), rank: 0 },
|
|
/* 3 */ Redirect { to: 2 }];
|
|
assert_eq!(get(&table, &0), &Some('x'));
|
|
}
|