diff options
Diffstat (limited to 'trunk/src/hashtab.h')
| -rw-r--r-- | trunk/src/hashtab.h | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/trunk/src/hashtab.h b/trunk/src/hashtab.h new file mode 100644 index 0000000..31e63e0 --- /dev/null +++ b/trunk/src/hashtab.h @@ -0,0 +1,155 @@ +/* An expandable hash tables datatype. + Copyright (C) 1999, 2000 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; if not, write to the Free Software +Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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); + +/* 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 */ |