netsurf/utils/hashtable.h
2018-04-22 14:03:18 +01:00

112 lines
3.8 KiB
C

/*
* Copyright 2006 Rob Kendrick <rjek@rjek.com>
*
* This file is part of NetSurf, http://www.netsurf-browser.org/
*
* NetSurf 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; version 2 of the License.
*
* NetSurf 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.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* \file
* Interface to Write-Once hash table for string to string mapping
*/
#ifndef _NETSURF_UTILS_HASHTABLE_H_
#define _NETSURF_UTILS_HASHTABLE_H_
#include <stdbool.h>
struct hash_table;
/**
* Create a new hash table
*
* Allocate a new hash table and return a context for it. The memory
* consumption of a hash table is approximately 8 + (nchains * 12)
* bytes if it is empty.
*
* \param chains Number of chains/buckets this hash table will have. This
* should be a prime number, and ideally a prime number just
* over a power of two, for best performance and distribution.
* \return struct hash_table containing the context of this hash table or NULL
* if there is insufficent memory to create it and its chains.
*/
struct hash_table *hash_create(unsigned int chains);
/**
* Destroys a hash table
*
* Destroy a hash table freeing all memory associated with it.
*
* \param ht Hash table to destroy. After the function returns, this
* will no longer be valid.
*/
void hash_destroy(struct hash_table *ht);
/**
* Adds a key/value pair to a hash table.
*
* If the key you're adding is already in the hash table, it does not
* replace it, but it does take precedent over it. The old key/value
* pair will be inaccessable but still in memory until hash_destroy()
* is called on the hash table.
*
* \param ht The hash table context to add the key/value pair to.
* \param key The key to associate the value with. A copy is made.
* \param value The value to associate the key with. A copy is made.
* \return true if the add succeeded, false otherwise. (Failure most likely
* indicates insufficent memory to make copies of the key and value.
*/
bool hash_add(struct hash_table *ht, const char *key, const char *value);
/**
* Looks up a the value associated with with a key from a specific hash table.
*
* \param ht The hash table context to look up the key in.
* \param key The key to search for.
* \return The value associated with the key, or NULL if it was not found.
*/
const char *hash_get(struct hash_table *ht, const char *key);
/**
* Add key/value pairs to a hash table with data from a file
*
* The file should be formatted as a series of lines terminated with
* newline character. Each line should contain a key/value pair
* separated by a colon. If a line is empty or starts with a #
* character it will be ignored.
*
* The file may be optionally gzip compressed.
*
* \param ht The hash table context to add the key/value pairs to.
* \param path Path to file with key/value pairs in.
* \return NSERROR_OK on success else error code
*/
nserror hash_add_file(struct hash_table *ht, const char *path);
/**
* Add key/value pairs to a hash table with data from a memory buffer
*
* The data format is the same as in hash_add_file() but held in memory
*
* The data may optionally be gzip compressed.
*
* \param ht The hash table context to add the key/value pairs to.
* \param data Source of key/value pairs
* \param size length of \a data
* \return NSERROR_OK on success else error code
*/
nserror hash_add_inline(struct hash_table *ht, const uint8_t *data, size_t size);
#endif