/*
* $Id: linkhash.h,v 1.6 2006/01/30 23:07:57 mclark Exp $
*
* Copyright (c) 2004, 2005 Metaparadigm Pte. Ltd.
* Michael Clark <michael@metaparadigm.com>
* Copyright (c) 2009 Hewlett-Packard Development Company, L.P.
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the MIT license. See COPYING for details.
*
*/
/**
* @file
* @brief Internal methods for working with json_type_object objects. Although
* this is exposed by the json_object_get_object() function and within the
* json_object_iter type, it is not recommended for direct use.
*/
#ifndef _linkhash_h_
#define _linkhash_h_
#include "json_object.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* golden prime used in hash functions
*/
#define LH_PRIME 0x9e370001UL
/**
* The fraction of filled hash buckets until an insert will cause the table
* to be resized.
* This can range from just above 0 up to 1.0.
*/
#define LH_LOAD_FACTOR 0.66
/**
* sentinel pointer value for empty slots
*/
#define LH_EMPTY (void *)-1
/**
* sentinel pointer value for freed slots
*/
#define LH_FREED (void *)-2
/**
* default string hash function
*/
#define JSON_C_STR_HASH_DFLT 0
/**
* perl-like string hash function
*/
#define JSON_C_STR_HASH_PERLLIKE 1
/**
* This function sets the hash function to be used for strings.
* Must be one of the JSON_C_STR_HASH_* values.
* @returns 0 - ok, -1 if parameter was invalid
*/
int json_global_set_string_hash(const int h);
struct lh_entry;
/**
* callback function prototypes
*/
typedef void(lh_entry_free_fn)(struct lh_entry *e);
/**
* callback function prototypes
*/
typedef unsigned long(lh_hash_fn)(const void *k);
/**
* callback function prototypes
*/
typedef int(lh_equal_fn)(const void *k1, const void *k2);
/**
* An entry in the hash table
*/
struct lh_entry
{
/**
* The key. Use lh_entry_k() instead of accessing this directly.
*/
const void *k;
/**
* A flag for users of linkhash to know whether or not they
* need to free k.
*/
int k_is_constant;
/**
* The value. Use lh_entry_v() instead of accessing this directly.
*/
const void *v;
/**
* The next entry
*/
struct lh_entry *next;
/**
* The previous entry.
*/
struct lh_entry *prev;
};
/**
* The hash table structure.
*/
struct lh_table
{
/**
* Size of our hash.
*/
int size;
/**
* Numbers of entries.
*/
int count;
/**
* The first entry.
*/
struct lh_entry *head;
/**
* The last entry.
*/
struct lh_entry *tail;
struct lh_entry *table;
/**
* A pointer onto the function responsible for freeing an entry.
*/
lh_entry_free_fn *free_fn;
lh_hash_fn *hash_fn;
lh_equal_fn *equal_fn;
};
typedef struct lh_table lh_table;
/**
* Convenience list iterator.
*/
#define lh_foreach(table, entry) for (entry = table->head; entry; entry = entry->next)
/**
* lh_foreach_safe allows calling of deletion routine while iterating.
*
* @param table a struct lh_table * to iterate over
* @param entry a struct lh_entry * variable to hold each element
* @param tmp a struct lh_entry * variable to hold a temporary pointer to the next element
*/
#define lh_foreach_safe(table, entry, tmp) \
for (entry = table->head; entry && ((tmp = entry->next) || 1); entry = tmp)
/**
* Create a new linkhash table.
*
* @param size initial table size. The table is automatically resized
* although this incurs a performance penalty.
* @param free_fn callback function used to free memory for entries
* when lh_table_free or lh_table_delete is called.
* If NULL is provided, then memory for keys and values
* must be freed by the caller.
* @param hash_fn function used to hash keys. 2 standard ones are defined:
* lh_ptr_hash and lh_char_hash for hashing pointer values
* and C strings respectively.
* @param equal_fn comparison function to compare keys. 2 standard ones defined:
* lh_ptr_hash and lh_char_hash for comparing pointer values
* and C strings respectively.
* @return On success, a pointer to the new linkhash table is returned.
* On error, a null pointer is returned.
*/
extern struct lh_table *lh_table_new(int size, lh_entry_free_fn *free_fn, lh_hash_fn *hash_fn,
lh_equal_fn *equal_fn);
/**
* Convenience function to create a new linkhash table with char keys.
*
* @param size initial table size.
* @param free_fn callback function used to free memory for entries.
* @return On success, a pointer to the new linkhash table is returned.
* On error, a null pointer is returned.
*/
extern struct lh_table *lh_kchar_table_new(int size, lh_entry_free_fn *free_fn);
/**
* Convenience function to create a new linkhash table with ptr keys.
*
* @param size initial table size.
* @param free_fn callback function used to free memory for entries.
* @return On success, a pointer to the new linkhash table is returned.
* On error, a null pointer is returned.
*/
extern struct lh_table *lh_kptr_table_new(int size, lh_entry_free_fn *free_fn);
/**
* Free a linkhash table.
*
* If a lh_entry_free_fn callback free function was provided then it is
* called for all entries in the table.
*
* @param t table to free.
*/
extern void lh_table_free(struct lh_table *t);
/**
* Insert a record into the table.
*
* @param t the table to insert into.
* @param k a pointer to the key to insert.
* @param v a pointer to the value to insert.
*
* @return On success, <code>0</code> is returned.
* On error, a negative value is returned.
*/
extern int lh_table_insert(struct lh_table *t, const void *k, const void *v);
/**
* Insert a record into the table using a precalculated key hash.
*
* The hash h, which should be calculated with lh_get_hash() on k, is provided by
* the caller, to allow for optimization when multiple operations with the same
* key are known to be needed.
*
* @param t the table to insert into.
* @param k a pointer to the key to insert.
* @param v a pointer to the value to insert.
* @param h hash value of the key to insert
* @param opts if set to JSON_C_OBJECT_KEY_IS_CONSTANT, sets lh_entry.k_is_constant
* so t's free function knows to avoid freeing the key.
*/
extern int lh_table_insert_w_hash(struct lh_table *t, const void *k, const void *v,
const unsigned long h, const unsigned opts);
/**
* Lookup a record in the table.
*
* @param t the table to lookup
* @param k a pointer to the key to lookup
* @return a pointer to the record structure of the value or NULL if it does not exist.
*/
extern struct lh_entry *lh_table_lookup_entry(struct lh_table *t, const void *k);
/**
* Lookup a record in the table using a precalculated key hash.
*
* The hash h, which should be calculated with lh_get_hash() on k, is provided by
* the caller, to allow for optimization when multiple operations with the same
* key are known to be needed.
*
* @param t the table to lookup
* @param k a pointer to the key to lookup
* @param h hash value of the key to lookup
* @return a pointer to the record structure of the value or NULL if it does not exist.
*/
extern struct lh_entry *lh_table_lookup_entry_w_hash(struct lh_table *t, const void *k,
const unsigned long h);
/**
* Lookup a record in the table.
*
* @param t the table to lookup
* @param k a pointer to the key to lookup
* @param v a pointer to a where to store the found value (set to NULL if it doesn't exist).
* @return whether or not the key was found
*/
extern json_bool lh_table_lookup_ex(struct lh_table *t, const void *k, void **v);
/**
* Delete a record from the table.
*
* If a callback free function is provided then it is called for the
* for the item being deleted.
* @param t the table to delete from.
* @param e a pointer to the entry to delete.
* @return 0 if the item was deleted.
* @return -1 if it was not found.
*/
extern int lh_table_delete_entry(struct lh_table *t, struct lh_entry *e);
/**
* Delete a record from the table.
*
* If a callback free function is provided then it is called for the
* for the item being deleted.
* @param t the table to delete from.
* @param k a pointer to the key to delete.
* @return 0 if the item was deleted.
* @return -1 if it was not found.
*/
extern int lh_table_delete(struct lh_table *t, const void *k);
extern int lh_table_length(struct lh_table *t);
/**
* Resizes the specified table.
*
* @param t Pointer to table to resize.
* @param new_size New table size. Must be positive.
*
* @return On success, <code>0</code> is returned.
* On error, a negative value is returned.
*/
int lh_table_resize(struct lh_table *t, int new_size);
/**
* @deprecated Don't use this outside of linkhash.h:
*/
#if !defined(_MSC_VER) || (_MSC_VER > 1800)
/* VS2010 can't handle inline funcs, so skip it there */
#define _LH_INLINE inline
#else
#define _LH_INLINE
#endif
/**
* Calculate the hash of a key for a given table.
*
* This is an exension to support functions that need to calculate
* the hash several times and allows them to do it just once and then pass
* in the hash to all utility functions. Depending on use case, this can be a
* considerable performance improvement.
* @param t the table (used to obtain hash function)
* @param k a pointer to the key to lookup
* @return the key's hash
*/
static _LH_INLINE unsigned long lh_get_hash(const struct lh_table *t, const void *k)
{
return t->hash_fn(k);
}
#undef _LH_INLINE
/**
* @deprecated Don't use this outside of linkhash.h:
*/
#ifdef __UNCONST
#define _LH_UNCONST(a) __UNCONST(a)
#else
#define _LH_UNCONST(a) ((void *)(uintptr_t)(const void *)(a))
#endif
/**
* Return a non-const version of lh_entry.k.
*
* lh_entry.k is const to indicate and help ensure that linkhash itself doesn't modify
* it, but callers are allowed to do what they want with it.
* See also lh_entry.k_is_constant
*/
#define lh_entry_k(entry) _LH_UNCONST((entry)->k)
/**
* Return a non-const version of lh_entry.v.
*
* v is const to indicate and help ensure that linkhash itself doesn't modify
* it, but callers are allowed to do what they want with it.
*/
#define lh_entry_v(entry) _LH_UNCONST((entry)->v)
#ifdef __cplusplus
}
#endif
#endif
