Add C++ wrapper around uthash.

1 files changed, 193 insertions, 0 deletions

diff --git a/src/rt/util/hash_map.h b/src/rt/util/hash_map.h
new file mode 100644
index 00000000..08d30837
--- /dev/null
+++ b/src/rt/util/hash_map.h
@@ -0,0 +1,193 @@
+/**
+ * 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 */