adding general purpose hash table

src/libstrongswan/utils/hashtable.h

@@ -0,0 +1,116 @@
+/*
+ * Copyright (C) 2008 Tobias Brunner
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ *
+ * $Id$
+ */
+
+/**
+ * @defgroup hashtable hashtable
+ * @{ @ingroup utils
+ */
+
+#ifndef HASHTABLE_H_
+#define HASHTABLE_H_
+
+#include <utils/enumerator.h>
+
+typedef struct hashtable_t hashtable_t;
+
+/**
+ * Prototype for a function that computes the hash code from the given key.
+ *
+ * @param key			key to hash
+ * @return				hash code
+ */
+typedef u_int (*hashtable_hash_t)(void *key);
+
+/**
+ * Prototype for a function that compares the two keys for equality.
+ *
+ * @param key			first key (the one we are looking for)
+ * @param other_key		second key
+ * @return				TRUE if the keys are equal
+ */
+typedef bool (*hashtable_equals_t)(void *key, void *other_key);
+
+/**
+ * Class implementing a hash table.
+ *
+ * General purpose hash table. This hash table is not synchronized.
+ */
+struct hashtable_t {
+	
+	/**
+	 * Create an enumerator over the hash table.
+	 * 
+	 * @return			enumerator over hash table entries
+	 */
+	enumerator_t *(*create_enumerator) (hashtable_t *this);
+	
+	/**
+	 * Adds the given value with the given key to the hash table, if there
+	 * exists no entry with that key. NULL is returned in this case.
+	 * Otherwise the existing value is replaced and the function returns the
+	 * old value.
+	 * 
+	 * @param key		the key to store
+	 * @param value		the value to store
+	 * @return			NULL if no item was replaced, the old value otherwise
+	 */
+	void *(*put) (hashtable_t *this, void *key, void *value);
+	
+	/**
+	 * Returns the value with the given key, if the hash table contains such an
+	 * entry, otherwise NULL is returned.
+	 * 
+	 * @param key		the key of the requested value
+	 * @return			the value, NULL if not found  
+	 */
+	void *(*get) (hashtable_t *this, void *key);
+	
+	/**
+	 * Removes the value with the given key from the hash table and returns the
+	 * removed value (or NULL if no such value existed).
+	 * 
+	 * @param key		the key of the value to remove
+	 * @return			the removed value, NULL if not found
+	 */
+	void *(*remove) (hashtable_t *this, void *key);
+	
+	/**
+	 * Gets the number of items in the hash table.
+	 * 
+	 * @return 			number of items
+	 */
+	u_int (*get_count) (hashtable_t *this);
+	
+	/**
+	 * Destroys a hash table object.
+	 */
+	void (*destroy) (hashtable_t *this);
+	
+};
+
+/**
+ * Creates an empty hash table object.
+ * 
+ * @param hash			hash function
+ * @param equals		equals function
+ * @param capacity		initial capacity
+ * @return 				hashtable_t object.
+ */
+hashtable_t *hashtable_create(hashtable_hash_t hash, hashtable_equals_t equals,
+							  u_int capacity);
+
+#endif /* HASHTABLE_H_ @} */