| // Copyright 2015 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| // Test associated types appearing in tuple-like enum variants. |
| |
| |
| use self::VarValue::*; |
| |
| pub trait UnifyKey { |
| type Value; |
| fn to_index(&self) -> usize; |
| } |
| |
| pub enum VarValue<K:UnifyKey> { |
| Redirect(K), |
| Root(K::Value, 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(ref k) => get(table, k), |
| VarValue::Root(ref v, _) => v, |
| } |
| } |
| |
| impl UnifyKey for usize { |
| type Value = Option<char>; |
| fn to_index(&self) -> usize { *self } |
| } |
| |
| fn main() { |
| let table = vec![/* 0 */ Redirect(1), |
| /* 1 */ Redirect(3), |
| /* 2 */ Root(Some('x'), 0), |
| /* 3 */ Redirect(2)]; |
| assert_eq!(get(&table, &0), &Some('x')); |
| } |