75 lines
1.8 KiB
Rust
75 lines
1.8 KiB
Rust
#[doc = "
|
|
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.
|
|
"];
|
|
|
|
import option::{some, none};
|
|
import option = option;
|
|
|
|
export treemap;
|
|
export init;
|
|
export insert;
|
|
export find;
|
|
export traverse;
|
|
|
|
type treemap<K, V> = @tree_node<K, V>;
|
|
|
|
enum tree_node<K, V> {
|
|
empty,
|
|
node(@K, @V, @tree_node<K, V>, @tree_node<K, V>)
|
|
}
|
|
|
|
#[doc = "Create a treemap"]
|
|
fn init<K, V>() -> treemap<K, V> { @empty }
|
|
|
|
#[doc = "Insert a value into the map"]
|
|
fn insert<K: copy, V: copy>(m: treemap<K, V>, k: K, v: V) -> treemap<K, V> {
|
|
@alt m {
|
|
@empty { node(@k, @v, @empty, @empty) }
|
|
@node(@kk, vv, left, right) {
|
|
if k < kk {
|
|
node(@kk, vv, insert(left, k, v), right)
|
|
} else if k == kk {
|
|
node(@kk, @v, left, right)
|
|
} else { node(@kk, vv, left, insert(right, k, v)) }
|
|
}
|
|
}
|
|
}
|
|
|
|
#[doc = "Find a value based on the key"]
|
|
fn find<K, V: copy>(m: treemap<K, V>, k: K) -> option<V> {
|
|
alt *m {
|
|
empty { none }
|
|
node(@kk, @v, left, right) {
|
|
if k == kk {
|
|
some(v)
|
|
} else if k < kk { find(left, k) } else { find(right, k) }
|
|
}
|
|
}
|
|
}
|
|
|
|
#[doc = "Visit all pairs in the map in order."]
|
|
fn traverse<K, V: copy>(m: treemap<K, V>, f: fn(K, V)) {
|
|
alt *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(@k, @v, left, right) {
|
|
// copy v to make aliases work out
|
|
let v1 = v;
|
|
traverse(left, f);
|
|
f(k, v1);
|
|
traverse(right, f);
|
|
}
|
|
}
|
|
}
|