145 lines
3.2 KiB
Rust
145 lines
3.2 KiB
Rust
/*!
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* A 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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import core::option::{some, none};
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import option = core::option;
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export treemap;
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export insert;
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export find;
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export traverse;
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type treemap<K, V> = @mut tree_edge<K, V>;
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type tree_edge<K, V> = option<@tree_node<K, V>>;
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enum tree_node<K, V> = {
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key: K,
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mut value: V,
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mut left: tree_edge<K, V>,
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mut right: tree_edge<K, V>
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};
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/// Create a treemap
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fn treemap<K, V>() -> treemap<K, V> { @mut none }
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/// Insert a value into the map
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fn insert<K: copy, V: copy>(m: &mut tree_edge<K, V>, k: K, v: V) {
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alt copy *m {
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none {
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*m = some(@tree_node({key: k,
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mut value: v,
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mut left: none,
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mut right: none}));
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ret;
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}
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some(node) {
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if k == node.key {
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node.value = v;
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} else if k < node.key {
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insert(&mut node.left, k, v);
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} else {
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insert(&mut node.right, k, v);
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}
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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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fn find<K: copy, V: copy>(m: &const tree_edge<K, V>, k: K) -> option<V> {
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alt copy *m {
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none { none }
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// FIXME (#2808): was that an optimization?
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some(node) {
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if k == node.key {
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some(node.value)
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} else if k < node.key {
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find(&const node.left, k)
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} else {
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find(&const node.right, k)
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}
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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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fn traverse<K, V: copy>(m: &const tree_edge<K, V>, f: fn(K, V)) {
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alt copy *m {
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none { }
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some(node) {
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traverse(&const node.left, f);
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// copy of value is req'd as f() requires an immutable ptr
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f(node.key, copy node.value);
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traverse(&const node.right, f);
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}
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}
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}
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#[cfg(test)]
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mod tests {
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#[test]
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fn init_treemap() { let _m = treemap::<int, int>(); }
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#[test]
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fn insert_one() { let m = treemap(); insert(m, 1, 2); }
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#[test]
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fn insert_two() { let m = treemap(); insert(m, 1, 2); insert(m, 3, 4); }
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#[test]
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fn insert_find() {
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let m = treemap();
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insert(m, 1, 2);
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assert (find(m, 1) == some(2));
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}
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#[test]
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fn find_empty() {
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let m = treemap::<int, int>(); assert (find(m, 1) == none);
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}
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#[test]
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fn find_not_found() {
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let m = treemap();
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insert(m, 1, 2);
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assert (find(m, 2) == none);
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}
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#[test]
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fn traverse_in_order() {
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let m = treemap();
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insert(m, 3, ());
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insert(m, 0, ());
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insert(m, 4, ());
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insert(m, 2, ());
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insert(m, 1, ());
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let n = @mut 0;
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fn t(n: @mut int, &&k: int, &&_v: ()) {
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assert (*n == k); *n += 1;
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}
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traverse(m, |x,y| t(n, x, y));
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}
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#[test]
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fn u8_map() {
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let m = treemap();
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let k1 = str::bytes(~"foo");
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let k2 = str::bytes(~"bar");
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insert(m, k1, ~"foo");
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insert(m, k2, ~"bar");
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assert (find(m, k2) == some(~"bar"));
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assert (find(m, k1) == some(~"foo"));
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}
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}
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