SQLite

#include <assert.h>
#include <stdlib.h>
#include <string.h>

#include "fts2_hash.h"




static void *malloc_and_zero(int n){
  void *p = malloc(n);
  if( p ){
    memset(p, 0, n);
  }
  return p;



}

/* Turn bulk memory into a hash table object by initializing the
** fields of the Hash structure.
**
** "pNew" is a pointer to the hash table that is to be initialized.
** keyClass is one of the constants 

  assert( keyClass>=FTS2_HASH_STRING && keyClass<=FTS2_HASH_BINARY );
  pNew->keyClass = keyClass;
  pNew->copyKey = copyKey;
  pNew->first = 0;
  pNew->count = 0;
  pNew->htsize = 0;
  pNew->ht = 0;
  pNew->xMalloc = malloc_and_zero;
  pNew->xFree = free;
}

/* Remove all entries from a hash table.  Reclaim all memory.
** Call this routine to delete a hash table or to reset a hash table
** to the empty state.
*/
void sqlite3Fts2HashClear(fts2Hash *pH){
  fts2HashElem *elem;         /* For looping over all elements of the table */

  assert( pH!=0 );
  elem = pH->first;
  pH->first = 0;
  if( pH->ht ) pH->xFree(pH->ht);
  pH->ht = 0;
  pH->htsize = 0;
  while( elem ){
    fts2HashElem *next_elem = elem->next;
    if( pH->copyKey && elem->pKey ){
      pH->xFree(elem->pKey);
    }
    pH->xFree(elem);
    elem = next_elem;
  }
  pH->count = 0;
}

/*
** Hash and comparison functions when the mode is FTS2_HASH_STRING

*/
static void rehash(fts2Hash *pH, int new_size){
  struct _fts2ht *new_ht;          /* The new hash table */
  fts2HashElem *elem, *next_elem;  /* For looping over existing elements */
  int (*xHash)(const void*,int);   /* The hash function */

  assert( (new_size & (new_size-1))==0 );
  new_ht = (struct _fts2ht *)pH->xMalloc( new_size*sizeof(struct _fts2ht) );
  if( new_ht==0 ) return;
  if( pH->ht ) pH->xFree(pH->ht);
  pH->ht = new_ht;
  pH->htsize = new_size;
  xHash = hashFunction(pH->keyClass);
  for(elem=pH->first, pH->first=0; elem; elem = next_elem){
    int h = (*xHash)(elem->pKey, elem->nKey) & (new_size-1);
    next_elem = elem->next;
    insertElement(pH, &new_ht[h], elem);

    pEntry->chain = elem->next;
  }
  pEntry->count--;
  if( pEntry->count<=0 ){
    pEntry->chain = 0;
  }
  if( pH->copyKey && elem->pKey ){
    pH->xFree(elem->pKey);
  }
  pH->xFree( elem );
  pH->count--;
  if( pH->count<=0 ){
    assert( pH->first==0 );
    assert( pH->count==0 );
    fts2HashClear(pH);
  }
}

      removeElementGivenHash(pH,elem,h);
    }else{
      elem->data = data;
    }
    return old_data;
  }
  if( data==0 ) return 0;
  new_elem = (fts2HashElem*)pH->xMalloc( sizeof(fts2HashElem) );
  if( new_elem==0 ) return data;
  if( pH->copyKey && pKey!=0 ){
    new_elem->pKey = pH->xMalloc( nKey );
    if( new_elem->pKey==0 ){
      pH->xFree(new_elem);
      return data;
    }
    memcpy((void*)new_elem->pKey, pKey, nKey);
  }else{
    new_elem->pKey = (void*)pKey;
  }
  new_elem->nKey = nKey;
  pH->count++;
  if( pH->htsize==0 ){
    rehash(pH,8);
    if( pH->htsize==0 ){
      pH->count = 0;
      pH->xFree(new_elem);
      return data;
    }
  }
  if( pH->count > pH->htsize ){
    rehash(pH,pH->htsize*2);
  }
  assert( pH->htsize>0 );

** this structure opaque.
*/
struct fts2Hash {
  char keyClass;          /* HASH_INT, _POINTER, _STRING, _BINARY */
  char copyKey;           /* True if copy of key made on insert */
  int count;              /* Number of entries in this table */
  fts2HashElem *first;    /* The first element of the array */
  void *(*xMalloc)(int);  /* malloc() function to use */
  void (*xFree)(void *);  /* free() function to use */
  int htsize;             /* Number of buckets in the hash table */
  struct _fts2ht {        /* the hash table */
    int count;               /* Number of entries with this hash */
    fts2HashElem *chain;     /* Pointer to first entry with this hash */
  } *ht;
};