text: /* Copyright (C) 2000 MySQL AB
  
     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 */
  
  /* Dynamic hashing of record with different key-length */
  
  #ifndef _hash_h
  #define _hash_h
  #ifdef	__cplusplus
  extern "C" {
  #endif
  
  /*
    Overhead to store an element in hash
    Can be used to approximate memory consumption for a hash
   */
  #define HASH_OVERHEAD (sizeof(char*)*2)
  
  typedef byte *(*hash_get_key)(const byte *,uint*,my_bool);
  typedef void (*hash_free_key)(void *);
  
  typedef struct st_hash {
    uint key_offset,key_length;		/* Length of key if const length */
    uint records,blength,current_record;
    uint flags;
    DYNAMIC_ARRAY array;				/* Place for hash_keys */
    hash_get_key get_key;
    void (*free)(void *);
    CHARSET_INFO *charset;
  } HASH;
  
  #define hash_init(A,B,C,D,E,F,G,H) _hash_init(A,B,C,D,E,F,G, H CALLER_INFO)
  my_bool _hash_init(HASH *hash, CHARSET_INFO *charset,
  		   uint default_array_elements, uint key_offset,
  		   uint key_length, hash_get_key get_key,
  		   void (*free_element)(void*), uint flags CALLER_INFO_PROTO);
  void hash_free(HASH *tree);
  void hash_reset(HASH *hash);
  byte *hash_element(HASH *hash,uint idx);
  gptr hash_search(HASH *info,const byte *key,uint length);
  gptr hash_next(HASH *info,const byte *key,uint length);
  my_bool my_hash_insert(HASH *info,const byte *data);
  my_bool hash_delete(HASH *hash,byte *record);
  my_bool hash_update(HASH *hash,byte *record,byte *old_key,uint old_key_length);
  void hash_replace(HASH *hash, uint idx, byte *new_row);
  my_bool hash_check(HASH *hash);			/* Only in debug library */
  
  #define hash_clear(H) bzero((char*) (H),sizeof(*(H)))
  #define hash_inited(H) ((H)->array.buffer != 0)
  
  #ifdef	__cplusplus
  }
  #endif
  #endif
  