src/test/run-pass/associated-types-enum-field-named.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // Test associated types appearing in struct-like enum variants.
  12
  13 use self::VarValue::*;
  14
  15 pub trait UnifyKey {
  16     type Value;
  17     fn to_index(&self) -> usize;
  18 }
  19
  20 pub enum VarValue<K:UnifyKey> {
  21     Redirect { to: K },
  22     Root { value: K::Value, rank: usize },
  23 }
  24
  25 fn get<'a,K:UnifyKey<Value=Option<V>>,V>(table: &'a Vec<VarValue<K>>, key: &K) -> &'a Option<V> {
  26     match table[key.to_index()] {
  27         VarValue::Redirect { to: ref k } => get(table, k),
  28         VarValue::Root { value: ref v, rank: _ } => v,
  29     }
  30 }
  31
  32 impl UnifyKey for usize {
  33     type Value = Option<char>;
  34     fn to_index(&self) -> usize { *self }
  35 }
  36
  37 fn main() {
  38     let table = vec![/* 0 */ Redirect { to: 1 },
  39                      /* 1 */ Redirect { to: 3 },
  40                      /* 2 */ Root { value: Some('x'), rank: 0 },
  41                      /* 3 */ Redirect { to: 2 }];
  42     assert_eq!(get(&table, &0), &Some('x'));
  43 }