+++ /dev/null
-/* -*-c-*-
- *
- * General hashtable infrastructure
- *
- * (c) 1999 Straylight/Edgeware
- */
-
-/*----- Licensing notice --------------------------------------------------*
- *
- * This file is part of the mLib utilities library.
- *
- * mLib is free software; you can redistribute it and/or modify
- * it under the terms of the GNU Library General Public License as
- * published by the Free Software Foundation; either version 2 of the
- * License, or (at your option) any later version.
- *
- * mLib 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 Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License along with mLib; if not, write to the Free
- * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
- * MA 02111-1307, USA.
- */
-
-#ifndef MLIB_HASH_H
-#define MLIB_HASH_H
-
-#ifdef __cplusplus
- extern "C" {
-#endif
-
-/*----- Notes -------------------------------------------------------------*
- *
- * This isn't a complete implementation of anything. It's a collection of
- * useful types and functions which will help when building hashtables of
- * things. The general-purpose hashtable is provided by the @sym@ functions.
- */
-
-/*----- Header files ------------------------------------------------------*/
-
-#include <stddef.h>
-
-#ifndef MLIB_ARENA_H
-# include "arena.h"
-#endif
-
-#ifndef MLIB_BITS_H
-# include "bits.h"
-#endif
-
-/*----- Data structures ---------------------------------------------------*/
-
-/* --- Hashtable basics --- *
- *
- * This contains the bare minimum to actually get anything useful done. In
- * particular it doesn't maintain any weighting information: when to extend
- * the table is left up to the particular implementation.
- */
-
-typedef struct hash_table {
- uint32 mask; /* Bit mask of hash bits */
- struct hash_base **v; /* Vector of hash bins */
- arena *a; /* Allocation arena */
-} hash_table;
-
-/* --- A hashtable entry --- *
- *
- * This is the bare minimum of what needs to be remembered in each hashtable
- * entry. Comparison of elements is left to the implementation, so I don't
- * need to know anything about how to represent hash keys here.
- */
-
-typedef struct hash_base {
- struct hash_base *next; /* Next entry in hash bin */
- uint32 hash; /* Hash value for this entry */
-} hash_base;
-
-/* --- A hashtable iterator --- */
-
-typedef struct hash_iter {
- hash_table *t; /* Hashtable being iterated */
- hash_base *p; /* Address of next item to return */
- size_t i; /* Index of next hash bin to use */
-} hash_iter;
-
-/*----- Functions provided ------------------------------------------------*/
-
-/* --- @hash_create@ --- *
- *
- * Arguments: @hash_table *t@ = pointer to hashtable to initialize
- * @size_t n@ = number of bins to allocate (zero initially)
- *
- * Returns: ---
- *
- * Use: Initializes a hashtable with a given number of bins. The
- * bins are initially empty. The number of bins must be a power
- * of two. This is not checked.
- */
-
-extern void hash_create(hash_table */*t*/, size_t /*n*/);
-
-/* --- @hash_destroy@ --- *
- *
- * Arguments: @hash_table *t@ = pointer to hashtable to destroy
- *
- * Returns: ---
- *
- * Use: Frees a hashtable. The items are not freed: they are the
- * responsibility of the implementation.
- */
-
-extern void hash_destroy(hash_table */*t*/);
-
-/* --- @hash_bin@ --- *
- *
- * Arguments: @hash_table *t@ = pointer to hashtable
- * @uint32 hash@ = hash value to look up
- *
- * Returns: Pointer to the bin's list head.
- *
- * Use: Given a hash value return the address of the appropriate list
- * head. It is safe to remove the current entry from the table.
- */
-
-#define HASH_BIN(t, hash) ((t)->v + ((hash) & (t)->mask))
-
-extern hash_base **hash_bin(hash_table */*t*/, uint32 /*hash*/);
-
-/* --- @hash_extend@ --- *
- *
- * Arguments: @hash_table *t@ = pointer to hashtable to extend
- *
- * Returns: Nonzero if extension was successful.
- *
- * Use: Extends a hashtable. The number of bins is doubled and the
- * entries are redistributed.
- */
-
-extern int hash_extend(hash_table */*t*/);
-
-/* --- @hash_remove@ --- *
- *
- * Arguments: @hash_table *t@ = pointer to hashtable
- * @hash_base *p@ = pointer to item to remove
- *
- * Returns: ---
- *
- * Use: Removes an item from a hashtable. The item itself is not
- * freed, although it is removed from the data structure and is
- * safe to free.
- */
-
-extern void hash_remove(hash_table */*t*/, hash_base */*p*/);
-
-/* --- @hash_mkiter@ --- *
- *
- * Arguments: @hash_iter *i@ = pointer to iterator to create
- * @hash_table *t@ = pointer to hashtable to iterate
- *
- * Returns: ---
- *
- * Use: Initializes a hashtable iterator.
- */
-
-#define HASH_MKITER(i_, t_) ((i_)->t = (t_), (i_)->p = 0, (i_)->i = 0)
-
-extern void hash_mkiter(hash_iter */*i*/, hash_table */*t*/);
-
-/* --- @hash_next@ --- *
- *
- * Arguments: @hash_iter *i@ = pointer to iterator
- *
- * Returns: Pointer to the next hashtable entry found, or null.
- *
- * Use: Returns the next entry from the hashtable.
- */
-
-#define HASH_NEXT(i_, b_) do { \
- hash_iter *_i = (i_); \
- hash_base *_p; \
- hash_table *_t = _i->t; \
- uint32 _m = _t->mask; \
- \
- for (;;) { \
- if (_i->p) { \
- _p = _i->p; \
- _i->p = _p->next; \
- break; \
- } else if (_i->i > _m) { \
- _p = 0; \
- break; \
- } else \
- _i->p = _t->v[_i->i++]; \
- } \
- (b_) = _p; \
-} while (0)
-
-extern hash_base *hash_next(hash_iter */*i*/);
-
-/*----- That's all, folks -------------------------------------------------*/
-
-#ifdef __cplusplus
- }
-#endif
-
-#endif
~mdw / mLib / blobdiff