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TreeMap: find_equiv(_mut) for str-like keys #15220

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TreeMap: find_equiv(_mut) for str-like keys #15220

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163 changes: 136 additions & 27 deletions src/libcollections/treemap.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -88,40 +88,18 @@ impl<K: Ord, V> Mutable for TreeMap<K, V> {
}

impl<K: Ord, V> Map<K, V> for TreeMap<K, V> {
// See comments on tree_find_with
#[inline]
fn find<'a>(&'a self, key: &K) -> Option<&'a V> {
let mut current = &self.root;
loop {
match *current {
Some(ref r) => {
match key.cmp(&r.key) {
Less => current = &r.left,
Greater => current = &r.right,
Equal => return Some(&r.value)
}
}
None => return None
}
}
tree_find_with(&self.root, |k2| key.cmp(k2))
}
}

impl<K: Ord, V> MutableMap<K, V> for TreeMap<K, V> {
// See comments on def_tree_find_mut_with
#[inline]
fn find_mut<'a>(&'a mut self, key: &K) -> Option<&'a mut V> {
let mut current = &mut self.root;
loop {
let temp = current; // hack to appease borrowck
match *temp {
Some(ref mut r) => {
match key.cmp(&r.key) {
Less => current = &mut r.left,
Greater => current = &mut r.right,
Equal => return Some(&mut r.value)
}
}
None => return None
}
}
tree_find_mut_with(&mut self.root, |x| key.cmp(x))
}

fn swap(&mut self, key: K, value: V) -> Option<V> {
Expand Down Expand Up @@ -194,6 +172,55 @@ impl<K: Ord, V> TreeMap<K, V> {
}
}

impl<K, V> TreeMap<K, V> {
/// Return the value for which f(key) returns Equal. f is invoked
/// with current key and helps to navigate the tree
///
/// # Example
///
/// ```
/// use std::ascii::StrAsciiExt;
///
/// let mut t = collections::treemap::TreeMap::new();
/// t.insert("Content-Type", "application/xml");
/// t.insert("User-Agent", "Curl-Rust/0.1");
///
/// let ua_key = "user-agent";
/// let ua = t.find_with(|&k| {
/// ua_key.cmp(&k.to_ascii_lower().as_slice())
/// });
///
/// assert_eq!(*ua.unwrap(), "Curl-Rust/0.1");
/// ```
#[inline]
pub fn find_with<'a>(&'a self, f:|&K| -> Ordering) -> Option<&'a V> {
tree_find_with(&self.root, f)
}

/// Return the value for which f(key) returns Equal. f is invoked
/// with current key and helps to navigate the tree
///
/// # Example
///
/// ```
/// let mut t = collections::treemap::TreeMap::new();
/// t.insert("Content-Type", "application/xml");
/// t.insert("User-Agent", "Curl-Rust/0.1");
///
/// let new_ua = "Safari/156.0";
/// match t.find_mut_with(|k| "User-Agent".cmp(k)) {
/// Some(x) => *x = new_ua,
/// None => fail!(),
/// }
///
/// assert_eq!(t.find(&"User-Agent"), Some(&new_ua));
/// ```
#[inline]
pub fn find_mut_with<'a>(&'a mut self, f:|&K| -> Ordering) -> Option<&'a mut V> {
tree_find_mut_with(&mut self.root, f)
}
}

// range iterators.

macro_rules! bound_setup {
Expand Down Expand Up @@ -853,6 +880,51 @@ fn split<K: Ord, V>(node: &mut Box<TreeNode<K, V>>) {
}
}

// Next 2 functions have the same conventions
//
// The only difference is that non-mutable version uses loop instead
// of recursion (performance considerations)
// It seems to be impossible to avoid recursion with mutability
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This is no longer the case. The mutable version is almost identical now, except for a temporary variable to appease borrowck

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Indeed, fixed in #15749

//
// So convention is that comparator is gets at input current key
// and returns search_key cmp cur_key (i.e. search_key.cmp(cur_key))
fn tree_find_with<'r, K, V>(node: &'r Option<Box<TreeNode<K, V>>>,
f: |&K| -> Ordering) -> Option<&'r V> {
let mut current: &'r Option<Box<TreeNode<K, V>>> = node;
loop {
match *current {
Some(ref r) => {
match f(&r.key) {
Less => current = &r.left,
Greater => current = &r.right,
Equal => return Some(&r.value)
}
}
None => return None
}
}
}

// See comments above tree_find_with
fn tree_find_mut_with<'r, K, V>(node: &'r mut Option<Box<TreeNode<K, V>>>,
f: |&K| -> Ordering) -> Option<&'r mut V> {

let mut current = node;
loop {
let temp = current; // hack to appease borrowck
match *temp {
Some(ref mut r) => {
match f(&r.key) {
Less => current = &mut r.left,
Greater => current = &mut r.right,
Equal => return Some(&mut r.value)
}
}
None => return None
}
}
}

fn insert<K: Ord, V>(node: &mut Option<Box<TreeNode<K, V>>>,
key: K, value: V) -> Option<V> {
match *node {
Expand Down Expand Up @@ -1024,6 +1096,30 @@ mod test_treemap {
assert_eq!(m.find(&2), None);
}

#[test]
fn find_with_empty() {
let m: TreeMap<&'static str,int> = TreeMap::new();
assert!(m.find_with(|k| "test".cmp(k)) == None);
}

#[test]
fn find_with_not_found() {
let mut m = TreeMap::new();
assert!(m.insert("test1", 2i));
assert!(m.insert("test2", 3i));
assert!(m.insert("test3", 3i));
assert_eq!(m.find_with(|k| "test4".cmp(k)), None);
}

#[test]
fn find_with_found() {
let mut m = TreeMap::new();
assert!(m.insert("test1", 2i));
assert!(m.insert("test2", 3i));
assert!(m.insert("test3", 4i));
assert_eq!(m.find_with(|k| "test2".cmp(k)), Some(&3i));
}

#[test]
fn test_find_mut() {
let mut m = TreeMap::new();
Expand All @@ -1037,6 +1133,19 @@ mod test_treemap {
assert_eq!(m.find(&5), Some(&new));
}

#[test]
fn test_find_with_mut() {
let mut m = TreeMap::new();
assert!(m.insert("t1", 12i));
assert!(m.insert("t2", 8));
assert!(m.insert("t5", 14));
let new = 100;
match m.find_mut_with(|k| "t5".cmp(k)) {
None => fail!(), Some(x) => *x = new
}
assert_eq!(m.find_with(|k| "t5".cmp(k)), Some(&new));
}

#[test]
fn insert_replace() {
let mut m = TreeMap::new();
Expand Down