/* hashlib.h -- the data structures used in hashing in Bash. */

/* Copyright (C) 1993 Free Software Foundation, Inc.

   This file is part of GNU Bash, the Bourne Again SHell.

   Bash 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, or (at your option) any later
   version.

   Bash 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 Bash; see the file COPYING.  If not, write to the Free Software
   Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA. */

#if !defined (_HASHLIB_H_)
#define _HASHLIB_H_

#include "stdc.h"

#ifndef PTR_T
#  ifdef __STDC__
#    define PTR_T void *
#  else
#    define PTR_T char *
#  endif
#endif

typedef struct bucket_contents {
  struct bucket_contents *next;	/* Link to next hashed key in this bucket. */
  char *key;			/* What we look up. */
  PTR_T data;			/* What we really want. */
  unsigned int khash;		/* What key hashes to */
  int times_found;		/* Number of times this item has been found. */
} BUCKET_CONTENTS;

typedef struct hash_table {
  BUCKET_CONTENTS **bucket_array;	/* Where the data is kept. */
  int nbuckets;			/* How many buckets does this table have. */
  int nentries;			/* How many entries does this table have. */
} HASH_TABLE;

typedef int hash_wfunc __P((BUCKET_CONTENTS *));

/* Operations on tables as a whole */
extern HASH_TABLE *hash_create __P((int));
extern HASH_TABLE *hash_copy __P((HASH_TABLE *, sh_string_func_t *));
extern void hash_flush __P((HASH_TABLE *, sh_free_func_t *));
extern void hash_dispose __P((HASH_TABLE *));
extern void hash_walk __P((HASH_TABLE *, hash_wfunc *));

/* Operations to extract information from or pieces of tables */
extern int hash_bucket __P((const char *, HASH_TABLE *));
extern int hash_size __P((HASH_TABLE *));

/* Operations on hash table entries */
extern BUCKET_CONTENTS *hash_search __P((const char *, HASH_TABLE *, int));
extern BUCKET_CONTENTS *hash_insert __P((char *, HASH_TABLE *, int));
extern BUCKET_CONTENTS *hash_remove __P((const char *, HASH_TABLE *, int));

/* Miscellaneous */
extern unsigned int hash_string __P((const char *));

/* Redefine the function as a macro for speed. */
#define hash_items(bucket, table) \
	((table && (bucket < table->nbuckets)) ?  \
		table->bucket_array[bucket] : \
		(BUCKET_CONTENTS *)NULL)

/* Default number of buckets in the hash table. */
#define DEFAULT_HASH_BUCKETS 64	/* was 107, then 53, must be power of two now */

#define HASH_ENTRIES(ht)	((ht) ? (ht)->nentries : 0)

/* flags for hash_search and hash_insert */
#define HASH_NOSRCH	0x01
#define HASH_CREATE	0x02

#if !defined (NULL)
#  if defined (__STDC__)
#    define NULL ((void *) 0)
#  else
#    define NULL 0x0
#  endif /* !__STDC__ */
#endif /* !NULL */

#endif /* _HASHLIB_H */
