rust/src/libstd/smallintmap.rs

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// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
/*!
* A simple map based on a vector for small integer keys. Space requirements
* are O(highest integer key).
*/
use core::container::{Container, Mutable, Map, Set};
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use core::old_iter::{BaseIter};
use core::option::{Some, None};
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use core::util::replace;
pub struct SmallIntMap<T> {
priv v: ~[Option<T>],
}
impl<V> Container for SmallIntMap<V> {
/// Return the number of elements in the map
fn len(&const self) -> uint {
let mut sz = 0;
for uint::range(0, vec::uniq_len(&const self.v)) |i| {
match self.v[i] {
Some(_) => sz += 1,
None => {}
}
}
sz
}
/// Return true if the map contains no elements
fn is_empty(&const self) -> bool { self.len() == 0 }
}
impl<V> Mutable for SmallIntMap<V> {
/// Clear the map, removing all key-value pairs.
fn clear(&mut self) { self.v.clear() }
}
impl<V> Map<uint, V> for SmallIntMap<V> {
/// Return true if the map contains a value for the specified key
fn contains_key(&self, key: &uint) -> bool {
self.find(key).is_some()
}
/// Visit all key-value pairs in order
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fn each<'a>(&'a self, it: &fn(&uint, &'a V) -> bool) -> bool {
for uint::range(0, self.v.len()) |i| {
match self.v[i] {
Some(ref elt) => if !it(&i, elt) { return false; },
None => ()
}
}
return true;
}
/// Visit all keys in order
fn each_key(&self, blk: &fn(key: &uint) -> bool) -> bool {
self.each(|k, _| blk(k))
}
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/// Visit all values in order
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fn each_value<'a>(&'a self, blk: &fn(value: &'a V) -> bool) -> bool {
self.each(|_, v| blk(v))
}
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/// Iterate over the map and mutate the contained values
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fn mutate_values(&mut self, it: &fn(&uint, &mut V) -> bool) -> bool {
for uint::range(0, self.v.len()) |i| {
match self.v[i] {
Some(ref mut elt) => if !it(&i, elt) { return false; },
None => ()
}
}
return true;
}
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/// Return a reference to the value corresponding to the key
fn find<'a>(&'a self, key: &uint) -> Option<&'a V> {
if *key < self.v.len() {
match self.v[*key] {
Some(ref value) => Some(value),
None => None
}
} else {
None
}
}
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/// Return a mutable reference to the value corresponding to the key
fn find_mut<'a>(&'a mut self, key: &uint) -> Option<&'a mut V> {
if *key < self.v.len() {
match self.v[*key] {
Some(ref mut value) => Some(value),
None => None
}
} else {
None
}
}
/// Insert a key-value pair into the map. An existing value for a
/// key is replaced by the new value. Return true if the key did
/// not already exist in the map.
fn insert(&mut self, key: uint, value: V) -> bool {
let exists = self.contains_key(&key);
let len = self.v.len();
if len <= key {
vec::grow_fn(&mut self.v, key - len + 1, |_| None);
}
self.v[key] = Some(value);
!exists
}
/// Remove a key-value pair from the map. Return true if the key
/// was present in the map, otherwise false.
fn remove(&mut self, key: &uint) -> bool {
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self.pop(key).is_some()
}
/// Insert a key-value pair from the map. If the key already had a value
/// present in the map, that value is returned. Otherwise None is returned.
fn swap(&mut self, key: uint, value: V) -> Option<V> {
match self.find_mut(&key) {
Some(loc) => { return Some(replace(loc, value)); }
None => ()
}
self.insert(key, value);
return None;
}
/// Removes a key from the map, returning the value at the key if the key
/// was previously in the map.
fn pop(&mut self, key: &uint) -> Option<V> {
if *key >= self.v.len() {
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return None;
}
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replace(&mut self.v[*key], None)
}
}
pub impl<V> SmallIntMap<V> {
/// Create an empty SmallIntMap
fn new() -> SmallIntMap<V> { SmallIntMap{v: ~[]} }
/// Visit all key-value pairs in reverse order
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fn each_reverse<'a>(&'a self, it: &fn(uint, &'a V) -> bool) -> bool {
for uint::range_rev(self.v.len(), 0) |i| {
match self.v[i - 1] {
Some(ref elt) => if !it(i - 1, elt) { return false; },
None => ()
}
}
return true;
}
fn get<'a>(&'a self, key: &uint) -> &'a V {
self.find(key).expect("key not present")
}
}
pub impl<V:Copy> SmallIntMap<V> {
fn update_with_key(&mut self, key: uint, val: V,
ff: &fn(uint, V, V) -> V) -> bool {
let new_val = match self.find(&key) {
None => val,
Some(orig) => ff(key, *orig, val)
};
self.insert(key, new_val)
}
fn update(&mut self, key: uint, newval: V, ff: &fn(V, V) -> V) -> bool {
self.update_with_key(key, newval, |_k, v, v1| ff(v,v1))
}
}
#[cfg(test)]
mod tests {
use super::SmallIntMap;
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#[test]
fn test_find_mut() {
let mut m = SmallIntMap::new();
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assert!(m.insert(1, 12));
assert!(m.insert(2, 8));
assert!(m.insert(5, 14));
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let new = 100;
match m.find_mut(&5) {
None => fail!(), Some(x) => *x = new
}
assert_eq!(m.find(&5), Some(&new));
}
#[test]
fn test_len() {
let mut map = SmallIntMap::new();
assert_eq!(map.len(), 0);
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assert!(map.is_empty());
assert!(map.insert(5, 20));
assert_eq!(map.len(), 1);
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assert!(!map.is_empty());
assert!(map.insert(11, 12));
assert_eq!(map.len(), 2);
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assert!(!map.is_empty());
assert!(map.insert(14, 22));
assert_eq!(map.len(), 3);
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assert!(!map.is_empty());
}
#[test]
fn test_clear() {
let mut map = SmallIntMap::new();
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assert!(map.insert(5, 20));
assert!(map.insert(11, 12));
assert!(map.insert(14, 22));
map.clear();
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assert!(map.is_empty());
assert!(map.find(&5).is_none());
assert!(map.find(&11).is_none());
assert!(map.find(&14).is_none());
}
#[test]
fn test_insert_with_key() {
let mut map = SmallIntMap::new();
// given a new key, initialize it with this new count, given
// given an existing key, add more to its count
fn addMoreToCount(_k: uint, v0: uint, v1: uint) -> uint {
v0 + v1
}
fn addMoreToCount_simple(v0: uint, v1: uint) -> uint {
v0 + v1
}
// count integers
map.update(3, 1, addMoreToCount_simple);
map.update_with_key(9, 1, addMoreToCount);
map.update(3, 7, addMoreToCount_simple);
map.update_with_key(5, 3, addMoreToCount);
map.update_with_key(3, 2, addMoreToCount);
// check the total counts
assert_eq!(map.find(&3).get(), &10);
assert_eq!(map.find(&5).get(), &3);
assert_eq!(map.find(&9).get(), &1);
// sadly, no sevens were counted
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assert!(map.find(&7).is_none());
}
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#[test]
fn test_swap() {
let mut m = SmallIntMap::new();
assert_eq!(m.swap(1, 2), None);
assert_eq!(m.swap(1, 3), Some(2));
assert_eq!(m.swap(1, 4), Some(3));
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}
#[test]
fn test_pop() {
let mut m = SmallIntMap::new();
m.insert(1, 2);
assert_eq!(m.pop(&1), Some(2));
assert_eq!(m.pop(&1), None);
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}
}