74 lines
2.2 KiB
Rust
74 lines
2.2 KiB
Rust
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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/*!
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* A functional key,value store that works on anything.
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*
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* This works using a binary search tree. In the first version, it's a
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* very naive algorithm, but it will probably be updated to be a
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* red-black tree or something else.
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*
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* This is copied and modified from treemap right now. It's missing a lot
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* of features.
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*/
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use std::cmp::{Eq, Ord};
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use std::option::{Some, None};
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pub type Treemap<K, V> = @TreeNode<K, V>;
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enum TreeNode<K, V> {
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Empty,
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Node(@K, @V, @TreeNode<K, V>, @TreeNode<K, V>)
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}
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/// Create a treemap
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pub fn init<K, V>() -> Treemap<K, V> { @Empty }
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/// Insert a value into the map
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pub fn insert<K:Eq + Ord,V>(m: Treemap<K, V>, k: K, v: V) -> Treemap<K, V> {
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@match m {
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@Empty => Node(@k, @v, @Empty, @Empty),
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@Node(kk, vv, left, right) => cond!(
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(k < *kk) { Node(kk, vv, insert(left, k, v), right) }
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(k == *kk) { Node(kk, @v, left, right) }
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_ { Node(kk, vv, left, insert(right, k, v)) }
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)
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}
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}
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/// Find a value based on the key
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pub fn find<K:Eq + Ord,V:Copy>(m: Treemap<K, V>, k: K) -> Option<V> {
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match *m {
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Empty => None,
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Node(kk, v, left, right) => cond!(
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(k == *kk) { Some(copy *v) }
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(k < *kk) { find(left, k) }
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_ { find(right, k) }
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)
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}
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}
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/// Visit all pairs in the map in order.
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pub fn traverse<K, V: Copy>(m: Treemap<K, V>, f: &fn(&K, &V)) {
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match *m {
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Empty => (),
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// Previously, this had what looked like redundant
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// matches to me, so I changed it. but that may be a
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// de-optimization -- tjc
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Node(@ref k, @ref v, left, right) => {
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traverse(left, |k,v| f(k,v));
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f(k, v);
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traverse(right, |k,v| f(k,v));
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}
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}
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}
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