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use core::util::swap;
// XXX turn this into a radix trie, probably
struct Trie<T> {
priv root: ~TrieNode<T>,
}
pub fn Trie<T> () -> Trie<T> {
Trie { root: ~TrieNode() }
}
struct TrieNode<T> {
priv value: Option<T>,
priv children: [Option<~TrieNode<T>>, ..256],
}
fn TrieNode<T> () -> TrieNode<T> {
TrieNode {
value: None,
// XXX can't just use [None, ..256] because of #5244
children: [
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
None, None, None, None, None, None, None, None,
],
}
}
impl<T> Trie<T> {
pub fn insert (&mut self, s: &str, v: T) {
if s.len() == 0 {
self.root.value = Some(v);
}
else {
let bytes = str::as_bytes_slice(s);
self.insert_vec(
&mut self.root.children[bytes[0]],
bytes.tail(),
v
);
}
}
pub fn find (&self, s: &str) -> &'self Option<T> {
let bytes = str::as_bytes_slice(s);
let (prefix_length, node) = self.root.find_prefix_trie(bytes);
if prefix_length == bytes.len() {
&node.value
}
else {
&None
}
}
pub fn has_prefix (&self, s: &str) -> bool {
let bytes = str::as_bytes_slice(s);
let (prefix_length, node) = self.root.find_prefix_trie(bytes);
if prefix_length == bytes.len() {
node.children.any(|child| { child.is_some() })
}
else {
false
}
}
fn insert_vec (&self, loc: &mut Option<~TrieNode<T>>, bytes: &[u8], v: T) {
let mut tmp = None;
swap(&mut tmp, loc);
let mut new = match tmp {
Some(node) => node,
None => ~TrieNode(),
};
if bytes.len() == 0 {
new.value = Some(v);
}
else {
self.insert_vec(&mut new.children[bytes[0]], bytes.tail(), v);
}
*loc = Some(new);
}
}
impl<T> TrieNode<T> {
fn find_prefix_trie (&self, bytes: &[u8]) -> (uint, &'self TrieNode<T>) {
if bytes.len() == 0 {
(0u, self)
}
else {
match self.children[bytes[0]] {
Some(ref t) => {
let (prefix_length, node) = t.find_prefix_trie(
bytes.tail()
);
(prefix_length + 1, node)
}
None => {
(0u, self)
}
}
}
}
}
#[test]
fn test_trie1 () {
let mut trie = Trie();
trie.insert("foo", 1);
trie.insert("bar", 2);
trie.insert("baz", 3);
check_not_exists(&trie, "");
check_not_exists(&trie, "f");
check_not_exists(&trie, "fo");
check_exists(&trie, "foo", 1);
check_not_exists(&trie, "foe");
check_not_exists(&trie, "food");
check_not_exists(&trie, "b");
check_not_exists(&trie, "ba");
check_exists(&trie, "bar", 2);
check_exists(&trie, "baz", 3);
check_not_exists(&trie, "bat");
check_not_exists(&trie, "bart");
check_not_exists(&trie, "barz");
check_not_exists(&trie, "quux");
check_has_prefix(&trie, "");
check_has_prefix(&trie, "f");
check_has_prefix(&trie, "b");
check_not_has_prefix(&trie, "q");
check_has_prefix(&trie, "fo");
check_has_prefix(&trie, "ba");
check_not_has_prefix(&trie, "fa");
check_not_has_prefix(&trie, "bo");
check_not_has_prefix(&trie, "qu");
check_not_has_prefix(&trie, "foo");
check_not_has_prefix(&trie, "bar");
check_not_has_prefix(&trie, "baz");
check_not_has_prefix(&trie, "for");
check_not_has_prefix(&trie, "bao");
check_not_has_prefix(&trie, "quu");
}
#[cfg(test)]
fn check_exists (trie: &Trie<int>, find: &str, value: int) {
match trie.find(find) {
&Some(v) => { assert!(v == value) }
&None => { fail!(fmt!("didn't find %?", find)) }
}
}
#[cfg(test)]
fn check_not_exists (trie: &Trie<int>, find: &str) {
match trie.find(find) {
&Some(_) => { fail!(fmt!("shouldn't find %?", find)) }
&None => ()
}
}
#[cfg(test)]
fn check_has_prefix (trie: &Trie<int>, find: &str) {
assert!(trie.has_prefix(find));
}
#[cfg(test)]
fn check_not_has_prefix (trie: &Trie<int>, find: &str) {
assert!(!trie.has_prefix(find));
}
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