Initial commit. lol

hash_table.h

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+/*
+ * Copyright © 2008 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * \file hash_table.h
+ * \brief Implementation of a generic, opaque hash table data type.
+ *
+ * \author Ian Romanick <ian.d.romanick@intel.com>
+ */
+
+#ifndef HASH_TABLE_H
+#define HASH_TABLE_H
+
+#include <string.h>
+
+struct hash_table;
+
+typedef unsigned (*hash_func_t)(const void *key);
+typedef int (*hash_compare_func_t)(const void *key1, const void *key2);
+
+/**
+ * Hash table constructor
+ *
+ * Creates a hash table with the specified number of buckets.  The supplied
+ * \c hash and \c compare routines are used when adding elements to the table
+ * and when searching for elements in the table.
+ *
+ * \param num_buckets  Number of buckets (bins) in the hash table.
+ * \param hash         Function used to compute hash value of input keys.
+ * \param compare      Function used to compare keys.
+ */
+extern struct hash_table *hash_table_ctor(unsigned num_buckets,
+    hash_func_t hash, hash_compare_func_t compare);
+
+
+/**
+ * Release all memory associated with a hash table
+ *
+ * \warning
+ * This function cannot release memory occupied either by keys or data.
+ */
+extern void hash_table_dtor(struct hash_table *ht);
+
+
+/**
+ * Flush all entries from a hash table
+ *
+ * \param ht  Table to be cleared of its entries.
+ */
+extern void hash_table_clear(struct hash_table *ht);
+
+
+/**
+ * Search a hash table for a specific element
+ *
+ * \param ht   Table to be searched
+ * \param key  Key of the desired element
+ *
+ * \return
+ * The \c data value supplied to \c hash_table_insert when the element with
+ * the matching key was added.  If no matching key exists in the table,
+ * \c NULL is returned.
+ */
+extern void *hash_table_find(struct hash_table *ht, const void *key);
+
+
+/**
+ * Add an element to a hash table
+ */
+extern void hash_table_insert(struct hash_table *ht, void *data,
+    const void *key);
+
+
+/**
+ * Compute hash value of a string
+ *
+ * Computes the hash value of a string using the DJB2 algorithm developed by
+ * Professor Daniel J. Bernstein.  It was published on comp.lang.c once upon
+ * a time.  I was unable to find the original posting in the archives.
+ *
+ * \param key  Pointer to a NUL terminated string to be hashed.
+ *
+ * \sa hash_table_string_compare
+ */
+extern unsigned hash_table_string_hash(const void *key);
+
+
+/**
+ * Compare two strings used as keys
+ *
+ * This is just a macro wrapper around \c strcmp.
+ *
+ * \sa hash_table_string_hash
+ */
+#define hash_table_string_compare ((hash_compare_func_t) strcmp)
+
+#endif /* HASH_TABLE_H */