* $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.
* @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.
* golden prime used in hash functions
#define LH_PRIME 0x9e370001UL
* The fraction of filled hash buckets until an insert will cause the table
* 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);
* 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
* The key. Use lh_entry_k() instead of accessing this directly.
* A flag for users of linkhash to know whether or not they
* The value. Use lh_entry_v() instead of accessing this directly.
* The hash table structure.
* A pointer onto the function responsible for freeing an entry.
lh_entry_free_fn *free_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,
* 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);
* 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 into the table.
* @param t the table to lookup
* @param k a pointer to the key to lookup
* @return a pointer to the found value or NULL if it does not exist.
* @deprecated Use lh_table_lookup_ex() instead.
THIS_FUNCTION_IS_DEPRECATED(extern const void* lh_table_lookup(struct lh_table *t, const void *k));
* 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);
* Prints a message to <code>stdout</code>,
* then exits the program with an exit code of <code>1</code>.
* @param msg Message format string, like for <code>printf</code>.
* @param ... Format args.
* @deprecated Since it is not a good idea to exit the entire program
* because of an internal library failure, json-c will no longer
* use this function internally.
* However, because its interface is public, it will remain part of
* the API on the off chance of legacy software using it externally.
THIS_FUNCTION_IS_DEPRECATED(void lh_abort(const char *msg, ...));
* 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
* 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
static _LH_INLINE unsigned long lh_get_hash(const struct lh_table *t, const void *k)
* @deprecated Don't use this outside of linkhash.h:
#define _LH_UNCONST(a) __UNCONST(a)
#define _LH_UNCONST(a) ((void *)(uintptr_t)(const void *)(a))
* 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)
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