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+/* An expandable hash tables datatype.
+ Copyright (C) 1999, 2000, 2002, 2003, 2004, 2005, 2009, 2010
+ Free Software Foundation, Inc.
+ Contributed by Vladimir Makarov (vmakarov@cygnus.com).
+
+This program 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; either version 2 of the License, or
+(at your option) any later version.
+
+This program 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; see the file COPYING. If not, write to
+the Free Software Foundation, 51 Franklin Street - Fifth Floor,
+Boston, MA 02110-1301, USA. */
+
+/* This package implements basic hash table functionality. It is possible
+ to search for an entry, create an entry and destroy an entry.
+
+ Elements in the table are generic pointers.
+
+ The size of the table is not fixed; if the occupancy of the table
+ grows too high the hash table will be expanded.
+
+ The abstract data implementation is based on generalized Algorithm D
+ from Knuth's book "The art of computer programming". Hash table is
+ expanded by creation of new hash table and transferring elements from
+ the old table to the new table. */
+
+#ifndef __HASHTAB_H__
+#define __HASHTAB_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+/* The type for a hash code. */
+typedef unsigned int hashval_t;
+
+/* Callback function pointer types. */
+
+/* Calculate hash of a table entry. */
+typedef hashval_t (*htab_hash) (const void *);
+
+/* Compare a table entry with a possible entry. The entry already in
+ the table always comes first, so the second element can be of a
+ different type (but in this case htab_find and htab_find_slot
+ cannot be used; instead the variants that accept a hash value
+ must be used). */
+typedef int (*htab_eq) (const void *, const void *);
+
+/* Cleanup function called whenever a live element is removed from
+ the hash table. */
+typedef void (*htab_del) (void *);
+
+/* Function called by htab_traverse for each live element. The first
+ arg is the slot of the element (which can be passed to htab_clear_slot
+ if desired), the second arg is the auxiliary pointer handed to
+ htab_traverse. Return 1 to continue scan, 0 to stop. */
+typedef int (*htab_trav) (void **, void *);
+
+/* Hash tables are of the following type. The structure
+ (implementation) of this type is not needed for using the hash
+ tables. All work with hash table should be executed only through
+ functions mentioned below. */
+
+struct htab
+{
+ /* Pointer to hash function. */
+ htab_hash hash_f;
+
+ /* Pointer to comparison function. */
+ htab_eq eq_f;
+
+ /* Pointer to cleanup function. */
+ htab_del del_f;
+
+ /* Table itself. */
+ void **entries;
+
+ /* Current size (in entries) of the hash table */
+ size_t size;
+
+ /* Current number of elements including also deleted elements */
+ size_t n_elements;
+
+ /* Current number of deleted elements in the table */
+ size_t n_deleted;
+
+ /* The following member is used for debugging. Its value is number
+ of all calls of `htab_find_slot' for the hash table. */
+ unsigned int searches;
+
+ /* The following member is used for debugging. Its value is number
+ of collisions fixed for time of work with the hash table. */
+ unsigned int collisions;
+
+ /* This is non-zero if we are allowed to return NULL for function calls
+ that allocate memory. */
+ int return_allocation_failure;
+};
+
+typedef struct htab *htab_t;
+
+/* An enum saying whether we insert into the hash table or not. */
+enum insert_option {NO_INSERT, INSERT};
+
+/* The prototypes of the package functions. */
+
+/* This function is like htab_create, but may return NULL if memory
+ allocation fails, and also signals that htab_find_slot_with_hash and
+ htab_find_slot are allowed to return NULL when inserting. */
+extern htab_t htab_try_create (size_t, htab_hash, htab_eq, htab_del);
+extern void htab_delete (htab_t);
+extern void htab_empty (htab_t);
+
+extern void *htab_find (htab_t, const void *);
+extern void **htab_find_slot (htab_t, const void *, enum insert_option);
+extern void *htab_find_with_hash (htab_t, const void *, hashval_t);
+extern void **htab_find_slot_with_hash (htab_t, const void *, hashval_t,
+ enum insert_option);
+extern void htab_clear_slot (htab_t, void **);
+extern void htab_remove_elt (htab_t, void *);
+
+extern void htab_traverse (htab_t, htab_trav, void *);
+
+extern size_t htab_size (htab_t);
+extern size_t htab_elements (htab_t);
+extern double htab_collisions (htab_t);
+
+/* Utility function. */
+unsigned long higher_prime_number (unsigned long);
+
+/* A hash function for pointers. */
+extern htab_hash htab_hash_pointer;
+
+/* An equality function for pointers. */
+extern htab_eq htab_eq_pointer;
+
+#ifndef NDEBUG
+
+#include <stdio.h>
+
+typedef void (*htab_dumpfn) (FILE *, const void *);
+typedef void *(*htab_restorefn) (FILE *);
+
+extern void htab_dump (htab_t, const char *, htab_dumpfn);
+extern void htab_restore (htab_t, const char *, htab_restorefn);
+
+#endif
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
+#endif /* __HASHTAB_H */