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// Copyright 2012 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.
/*!
* A functional key,value store that works on anything.
*
* This works using a binary search tree. In the first version, it's a
* very naive algorithm, but it will probably be updated to be a
* red-black tree or something else.
*
* This is copied and modified from treemap right now. It's missing a lot
* of features.
*/
use std::cmp::{Eq, Ord};
use std::option::{Some, None};
pub type Treemap<K, V> = @TreeNode<K, V>;
enum TreeNode<K, V> {
Empty,
Node(@K, @V, @TreeNode<K, V>, @TreeNode<K, V>)
}
/// Create a treemap
pub fn init<K, V>() -> Treemap<K, V> { @Empty }
/// Insert a value into the map
pub fn insert<K:Eq + Ord,V>(m: Treemap<K, V>, k: K, v: V) -> Treemap<K, V> {
@match m {
@Empty => Node(@k, @v, @Empty, @Empty),
@Node(kk, vv, left, right) => cond!(
(k < *kk) { Node(kk, vv, insert(left, k, v), right) }
(k == *kk) { Node(kk, @v, left, right) }
_ { Node(kk, vv, left, insert(right, k, v)) }
)
}
}
/// Find a value based on the key
pub fn find<K:Eq + Ord,V:Copy>(m: Treemap<K, V>, k: K) -> Option<V> {
match *m {
Empty => None,
Node(kk, v, left, right) => cond!(
(k == *kk) { Some(copy *v) }
(k < *kk) { find(left, k) }
_ { find(right, k) }
)
}
}
/// Visit all pairs in the map in order.
pub fn traverse<K, V: Copy>(m: Treemap<K, V>, f: &fn(&K, &V)) {
match *m {
Empty => (),
// Previously, this had what looked like redundant
// matches to me, so I changed it. but that may be a
// de-optimization -- tjc
Node(@ref k, @ref v, left, right) => {
traverse(left, |k,v| f(k,v));
f(k, v);
traverse(right, |k,v| f(k,v));
}
}
}
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