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/*!
* A 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.
*/
#[forbid(deprecated_mode)];
use core::cmp::{Eq, Ord};
use core::option::{Some, None};
use Option = core::Option;
pub type TreeMap<K, V> = @mut TreeEdge<K, V>;
type TreeEdge<K, V> = Option<@TreeNode<K, V>>;
enum TreeNode<K, V> = {
key: K,
mut value: V,
mut left: TreeEdge<K, V>,
mut right: TreeEdge<K, V>
};
/// Create a treemap
pub fn TreeMap<K, V>() -> TreeMap<K, V> { @mut None }
/// Insert a value into the map
pub fn insert<K: Copy Eq Ord, V: Copy>(m: &mut TreeEdge<K, V>, k: K, v: V) {
match copy *m {
None => {
*m = Some(@TreeNode({key: k,
mut value: v,
mut left: None,
mut right: None}));
return;
}
Some(node) => {
if k == node.key {
node.value = v;
} else if k < node.key {
insert(&mut node.left, k, v);
} else {
insert(&mut node.right, k, v);
}
}
};
}
/// Find a value based on the key
pub fn find<K: Copy Eq Ord, V: Copy>(m: &const TreeEdge<K, V>, k: K)
-> Option<V> {
match copy *m {
None => None,
// FIXME (#2808): was that an optimization?
Some(node) => {
if k == node.key {
Some(node.value)
} else if k < node.key {
find(&const node.left, k)
} else {
find(&const node.right, k)
}
}
}
}
/// Visit all pairs in the map in order.
pub fn traverse<K, V: Copy>(m: &const TreeEdge<K, V>, f: fn((&K), (&V))) {
match copy *m {
None => (),
Some(node) => {
traverse(&const node.left, f);
// copy of value is req'd as f() requires an immutable ptr
f(&node.key, © node.value);
traverse(&const node.right, f);
}
}
}
#[cfg(test)]
mod tests {
#[legacy_exports];
#[test]
fn init_treemap() { let _m = TreeMap::<int, int>(); }
#[test]
fn insert_one() { let m = TreeMap(); insert(m, 1, 2); }
#[test]
fn insert_two() { let m = TreeMap(); insert(m, 1, 2); insert(m, 3, 4); }
#[test]
fn insert_find() {
let m = TreeMap();
insert(m, 1, 2);
assert (find(m, 1) == Some(2));
}
#[test]
fn find_empty() {
let m = TreeMap::<int, int>(); assert (find(m, 1) == None);
}
#[test]
fn find_not_found() {
let m = TreeMap();
insert(m, 1, 2);
assert (find(m, 2) == None);
}
#[test]
fn traverse_in_order() {
let m = TreeMap();
insert(m, 3, ());
insert(m, 0, ());
insert(m, 4, ());
insert(m, 2, ());
insert(m, 1, ());
let n = @mut 0;
fn t(n: @mut int, k: int, _v: ()) {
assert (*n == k); *n += 1;
}
traverse(m, |x,y| t(n, *x, *y));
}
#[test]
fn u8_map() {
let m = TreeMap();
let k1 = str::to_bytes(~"foo");
let k2 = str::to_bytes(~"bar");
insert(m, k1, ~"foo");
insert(m, k2, ~"bar");
assert (find(m, k2) == Some(~"bar"));
assert (find(m, k1) == Some(~"foo"));
}
}
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