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// -*- c++ -*-
/**
* A C++ wrapper around uthash.
*/
#ifndef HASH_MAP
#define HASH_MAP
#include <assert.h>
#include "../uthash/uthash.h"
template<typename K, typename V> class hash_map {
struct map_entry {
K key;
V value;
UT_hash_handle hh;
};
map_entry * _head;
public:
hash_map();
~hash_map();
/**
* Associates a value with the specified key in this hash map.
* If a mapping already exists the old value is replaced.
*
* returns:
* true if the mapping was successfully created and false otherwise.
*/
bool put(K key, V value);
/**
* Updates the value associated with the specified key in this hash map.
*
* returns:
* true if the value was updated, or false if the key was not found.
*/
bool set(K key, V value);
/**
* Gets the value associated with the specified key in this hash map.
*
* returns:
* true if the value was found and updates the specified *value parameter
* with the associated value, or false otherwise.
*/
bool get(K key, V *value);
/**
* Removes a key-value pair from this hash map.
*
* returns:
* true if a key-value pair exists and updates the specified
* *key and *value parameters, or false otherwise.
*/
bool pop(K *key, V *value);
/**
* Checks if the specified key exists in this hash map.
*
* returns:
* true if the specified key exists in this hash map, or false otherwise.
*/
bool contains(K key);
/**
* Removes the value associated with the specified key from this hash map.
*
* returns:
* true if the specified key exists and updates the specified *old_value
* parameter with the associated value, or false otherwise.
*/
bool remove(K key, V *old_value);
bool remove(K key);
/**
* Returns the number of key-value pairs in this hash map.
*/
size_t count();
bool is_empty() {
return count() == 0;
}
/**
* Clears all the key-value pairs in this hash map.
*
* returns:
* the number of deleted key-value pairs.
*/
size_t clear();
};
template<typename K, typename V>
hash_map<K,V>::hash_map() {
_head = NULL;
}
template<typename K, typename V>
hash_map<K,V>::~hash_map() {
clear();
}
template<typename K, typename V> bool
hash_map<K,V>::put(K key, V value) {
if (contains(key)) {
return set(key, value);
}
map_entry *entry = (map_entry *) malloc(sizeof(map_entry));
entry->key = key;
entry->value = value;
HASH_ADD(hh, _head, key, sizeof(K), entry);
return true;
}
template<typename K, typename V> bool
hash_map<K,V>::get(K key, V *value) {
map_entry *entry = NULL;
HASH_FIND(hh, _head, &key, sizeof(K), entry);
if (entry == NULL) {
return false;
}
*value = entry->value;
return true;
}
template<typename K, typename V> bool
hash_map<K,V>::set(K key, V value) {
map_entry *entry = NULL;
HASH_FIND(hh, _head, &key, sizeof(K), entry);
if (entry == NULL) {
return false;
}
entry->value = value;
return true;
}
template<typename K, typename V> bool
hash_map<K,V>::contains(K key) {
V value;
return get(key, &value);
}
template<typename K, typename V> bool
hash_map<K,V>::remove(K key, V *old_value) {
map_entry *entry = NULL;
HASH_FIND(hh, _head, &key, sizeof(K), entry);
if (entry == NULL) {
return false;
}
*old_value = entry->value;
HASH_DEL(_head, entry);
free(entry);
return true;
}
template<typename K, typename V> bool
hash_map<K,V>::pop(K *key, V *value) {
if (is_empty()) {
return false;
}
map_entry *entry = _head;
HASH_DEL(_head, entry);
*key = entry->key;
*value = entry->value;
free(entry);
return true;
}
template<typename K, typename V> bool
hash_map<K,V>::remove(K key) {
V old_value;
return remove(key, &old_value);
}
template<typename K, typename V> size_t
hash_map<K,V>::count() {
return HASH_CNT(hh, _head);
}
template<typename K, typename V> size_t
hash_map<K,V>::clear() {
size_t deleted_entries = 0;
while (_head != NULL) {
map_entry *entry = _head;
HASH_DEL(_head, entry);
free(entry);
deleted_entries ++;
}
assert(count() == 0);
return deleted_entries;
}
#endif /* HASH_MAP */
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