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treemap: use an &mut parameter for skew and split

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results in a small performance improvement and reduces the compiled
code size
This commit is contained in:
Daniel Micay 2013-02-10 20:37:21 -05:00
parent 9d7014e55c
commit f9c15de1fd
1 changed files with 28 additions and 19 deletions
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47
src/libstd/treemap.rs
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@ -576,29 +576,25 @@ pure fn each_reverse<K: Ord, V>(node: &r/Option<~TreeNode<K, V>>,
}
// Remove left horizontal link by rotating right
fn skew<K: Ord, V>(mut node: ~TreeNode<K, V>) -> ~TreeNode<K, V> {
fn skew<K: Ord, V>(node: &mut ~TreeNode<K, V>) {
if node.left.map_default(false, |x| x.level == node.level) {
let mut save = node.left.swap_unwrap();
node.left <-> save.right; // save.right now None
save.right = Some(node);
save
} else {
node // nothing to do
*node <-> save;
node.right = Some(save);
}
}
// Remove dual horizontal link by rotating left and increasing level of
// the parent
fn split<K: Ord, V>(mut node: ~TreeNode<K, V>) -> ~TreeNode<K, V> {
fn split<K: Ord, V>(node: &mut ~TreeNode<K, V>) {
if node.right.map_default(false,
|x| x.right.map_default(false, |y| y.level == node.level)) {
let mut save = node.right.swap_unwrap();
node.right <-> save.left; // save.left now None
save.left = Some(node);
save.level += 1;
save
} else {
node // nothing to do
*node <-> save;
node.left = Some(save);
}
}
@ -611,11 +607,15 @@ fn insert<K: Ord, V>(node: &mut Option<~TreeNode<K, V>>, key: K,
let mut save = node.swap_unwrap();
if key < save.key {
let inserted = insert(&mut save.left, key, value);
*node = Some(split(skew(save))); // re-balance, if necessary
skew(&mut save);
split(&mut save);
*node = Some(save); // re-balance, if necessary
inserted
} else if save.key < key {
let inserted = insert(&mut save.right, key, value);
*node = Some(split(skew(save))); // re-balance, if necessary
skew(&mut save);
split(&mut save);
*node = Some(save); // re-balance, if necessary
inserted
} else {
save.key = key;
@ -684,15 +684,24 @@ fn remove<K: Ord, V>(node: &mut Option<~TreeNode<K, V>>, key: &K) -> bool {
do save.right.mutate |mut x| { x.level = save.level; x }
}
save = skew(save);
skew(&mut save);
do save.right.mutate |mut right| {
right = skew(right);
right.right.mutate(skew);
right
match save.right {
Some(ref mut right) => {
skew(right);
match right.right {
Some(ref mut x) => { skew(x) },
None => ()
}
}
None => ()
}
split(&mut save);
match save.right {
Some(ref mut x) => { split(x) },
None => ()
}
save = split(save);
save.right.mutate(split);
}
*node = Some(save);