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240 行
9.1 KiB
240 行
9.1 KiB
/*
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* Hash Table Data Type
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* Copyright (C) 1997 Kaz Kylheku <kaz@ashi.footprints.net>
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*
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* Free Software License:
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*
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* All rights are reserved by the author, with the following exceptions:
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* Permission is granted to freely reproduce and distribute this software,
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* possibly in exchange for a fee, provided that this copyright notice appears
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* intact. Permission is also granted to adapt this software to produce
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* derivative works, as long as the modified versions carry this copyright
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* notice and additional notices stating that the work has been modified.
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* This source code may be translated into executable form and incorporated
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* into proprietary software; there is no requirement for such software to
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* contain a copyright notice related to this source.
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*
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* $Id: hash.h,v 1.22.2.7 2000/11/13 01:36:45 kaz Exp $
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* $Name: kazlib_1_20 $
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*/
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#ifndef HASH_H
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#define HASH_H
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#include <limits.h>
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#ifdef KAZLIB_SIDEEFFECT_DEBUG
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#include "sfx.h"
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#endif
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/*
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* Blurb for inclusion into C++ translation units
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef unsigned long hashcount_t;
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#define HASHCOUNT_T_MAX ULONG_MAX
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typedef unsigned long hash_val_t;
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#define HASH_VAL_T_MAX ULONG_MAX
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extern int hash_val_t_bit;
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#ifndef HASH_VAL_T_BIT
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#define HASH_VAL_T_BIT ((int) hash_val_t_bit)
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#endif
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/*
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* Hash chain node structure.
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* Notes:
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* 1. This preprocessing directive is for debugging purposes. The effect is
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* that if the preprocessor symbol KAZLIB_OPAQUE_DEBUG is defined prior to the
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* inclusion of this header, then the structure shall be declared as having
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* the single member int __OPAQUE__. This way, any attempts by the
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* client code to violate the principles of information hiding (by accessing
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* the structure directly) can be diagnosed at translation time. However,
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* note the resulting compiled unit is not suitable for linking.
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* 2. This is a pointer to the next node in the chain. In the last node of a
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* chain, this pointer is null.
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* 3. The key is a pointer to some user supplied data that contains a unique
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* identifier for each hash node in a given table. The interpretation of
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* the data is up to the user. When creating or initializing a hash table,
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* the user must supply a pointer to a function for comparing two keys,
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* and a pointer to a function for hashing a key into a numeric value.
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* 4. The value is a user-supplied pointer to void which may refer to
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* any data object. It is not interpreted in any way by the hashing
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* module.
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* 5. The hashed key is stored in each node so that we don't have to rehash
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* each key when the table must grow or shrink.
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*/
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typedef struct hnode_t {
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#if defined(HASH_IMPLEMENTATION) || !defined(KAZLIB_OPAQUE_DEBUG) /* 1 */
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struct hnode_t *hash_next; /* 2 */
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const void *hash_key; /* 3 */
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void *hash_data; /* 4 */
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hash_val_t hash_hkey; /* 5 */
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#else
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int hash_dummy;
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#endif
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} hnode_t;
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/*
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* The comparison function pointer type. A comparison function takes two keys
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* and produces a value of -1 if the left key is less than the right key, a
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* value of 0 if the keys are equal, and a value of 1 if the left key is
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* greater than the right key.
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*/
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typedef int (*hash_comp_t)(const void *, const void *);
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/*
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* The hashing function performs some computation on a key and produces an
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* integral value of type hash_val_t based on that key. For best results, the
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* function should have a good randomness properties in *all* significant bits
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* over the set of keys that are being inserted into a given hash table. In
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* particular, the most significant bits of hash_val_t are most significant to
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* the hash module. Only as the hash table expands are less significant bits
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* examined. Thus a function that has good distribution in its upper bits but
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* not lower is preferrable to one that has poor distribution in the upper bits
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* but not the lower ones.
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*/
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typedef hash_val_t (*hash_fun_t)(const void *);
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/*
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* allocator functions
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*/
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typedef hnode_t *(*hnode_alloc_t)(void *);
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typedef void (*hnode_free_t)(hnode_t *, void *);
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/*
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* This is the hash table control structure. It keeps track of information
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* about a hash table, as well as the hash table itself.
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* Notes:
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* 1. Pointer to the hash table proper. The table is an array of pointers to
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* hash nodes (of type hnode_t). If the table is empty, every element of
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* this table is a null pointer. A non-null entry points to the first
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* element of a chain of nodes.
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* 2. This member keeps track of the size of the hash table---that is, the
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* number of chain pointers.
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* 3. The count member maintains the number of elements that are presently
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* in the hash table.
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* 4. The maximum count is the greatest number of nodes that can populate this
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* table. If the table contains this many nodes, no more can be inserted,
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* and the hash_isfull() function returns true.
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* 5. The high mark is a population threshold, measured as a number of nodes,
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* which, if exceeded, will trigger a table expansion. Only dynamic hash
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* tables are subject to this expansion.
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* 6. The low mark is a minimum population threshold, measured as a number of
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* nodes. If the table population drops below this value, a table shrinkage
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* will occur. Only dynamic tables are subject to this reduction. No table
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* will shrink beneath a certain absolute minimum number of nodes.
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* 7. This is the a pointer to the hash table's comparison function. The
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* function is set once at initialization or creation time.
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* 8. Pointer to the table's hashing function, set once at creation or
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* initialization time.
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* 9. The current hash table mask. If the size of the hash table is 2^N,
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* this value has its low N bits set to 1, and the others clear. It is used
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* to select bits from the result of the hashing function to compute an
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* index into the table.
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* 10. A flag which indicates whether the table is to be dynamically resized. It
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* is set to 1 in dynamically allocated tables, 0 in tables that are
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* statically allocated.
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*/
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typedef struct hash_t {
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#if defined(HASH_IMPLEMENTATION) || !defined(KAZLIB_OPAQUE_DEBUG)
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struct hnode_t **hash_table; /* 1 */
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hashcount_t hash_nchains; /* 2 */
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hashcount_t hash_nodecount; /* 3 */
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hashcount_t hash_maxcount; /* 4 */
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hashcount_t hash_highmark; /* 5 */
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hashcount_t hash_lowmark; /* 6 */
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hash_comp_t hash_compare; /* 7 */
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hash_fun_t hash_function; /* 8 */
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hnode_alloc_t hash_allocnode;
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hnode_free_t hash_freenode;
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void *hash_context;
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hash_val_t hash_mask; /* 9 */
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int hash_dynamic; /* 10 */
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#else
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int hash_dummy;
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#endif
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} hash_t;
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/*
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* Hash scanner structure, used for traversals of the data structure.
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* Notes:
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* 1. Pointer to the hash table that is being traversed.
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* 2. Reference to the current chain in the table being traversed (the chain
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* that contains the next node that shall be retrieved).
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* 3. Pointer to the node that will be retrieved by the subsequent call to
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* hash_scan_next().
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*/
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typedef struct hscan_t {
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#if defined(HASH_IMPLEMENTATION) || !defined(KAZLIB_OPAQUE_DEBUG)
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hash_t *hash_table; /* 1 */
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hash_val_t hash_chain; /* 2 */
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hnode_t *hash_next; /* 3 */
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#else
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int hash_dummy;
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#endif
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} hscan_t;
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extern hash_t *kl_hash_create(hashcount_t, hash_comp_t, hash_fun_t);
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extern void kl_hash_set_allocator(hash_t *, hnode_alloc_t, hnode_free_t, void *);
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extern void kl_hash_destroy(hash_t *);
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extern void kl_hash_free_nodes(hash_t *);
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extern void kl_hash_free(hash_t *);
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extern hash_t *kl_hash_init(hash_t *, hashcount_t, hash_comp_t,
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hash_fun_t, hnode_t **, hashcount_t);
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extern void kl_hash_insert(hash_t *, hnode_t *, const void *);
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extern hnode_t *kl_hash_lookup(hash_t *, const void *);
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extern hnode_t *kl_hash_delete(hash_t *, hnode_t *);
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extern int kl_hash_alloc_insert(hash_t *, const void *, void *);
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extern void kl_hash_delete_free(hash_t *, hnode_t *);
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extern void kl_hnode_put(hnode_t *, void *);
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extern void *kl_hnode_get(hnode_t *);
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extern const void *kl_hnode_getkey(hnode_t *);
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extern hashcount_t kl_hash_count(hash_t *);
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extern hashcount_t kl_hash_size(hash_t *);
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extern int kl_hash_isfull(hash_t *);
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extern int kl_hash_isempty(hash_t *);
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extern void kl_hash_scan_begin(hscan_t *, hash_t *);
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extern hnode_t *kl_hash_scan_next(hscan_t *);
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extern hnode_t *kl_hash_scan_delete(hash_t *, hnode_t *);
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extern void kl_hash_scan_delfree(hash_t *, hnode_t *);
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extern int kl_hash_verify(hash_t *);
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extern hnode_t *kl_hnode_create(void *);
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extern hnode_t *kl_hnode_init(hnode_t *, void *);
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extern void kl_hnode_destroy(hnode_t *);
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#if defined(HASH_IMPLEMENTATION) || !defined(KAZLIB_OPAQUE_DEBUG)
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#ifdef KAZLIB_SIDEEFFECT_DEBUG
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#define kl_hash_isfull(H) (SFX_CHECK(H)->hash_nodecount == (H)->hash_maxcount)
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#else
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#define kl_hash_isfull(H) ((H)->hash_nodecount == (H)->hash_maxcount)
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#endif
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#define kl_hash_isempty(H) ((H)->hash_nodecount == 0)
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#define kl_hash_count(H) ((H)->hash_nodecount)
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#define kl_hash_size(H) ((H)->hash_nchains)
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#define kl_hnode_get(N) ((N)->hash_data)
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#define kl_hnode_getkey(N) ((N)->hash_key)
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#define kl_hnode_put(N, V) ((N)->hash_data = (V))
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#endif
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#ifdef __cplusplus
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}
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#endif
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#endif
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