/*

 ** 2001 September 22

 **

 ** The author disclaims copyright to this source code.  In place of

 ** a legal notice, here is a blessing:

 **

 **    May you do good and not evil.

 **    May you find forgiveness for yourself and forgive others.

 **    May you share freely, never taking more than you give.

 **

 *************************************************************************

 ** This is the header file for the generic hash-table implemenation

 ** used in SQLite.  We've modified it slightly to serve as a standalone

 ** hash table implementation for the full-text indexing module.

 **

 */

 #ifndef _FTS3_HASH_H_

 #define _FTS3_HASH_H_

 /* Forward declarations of structures. */

 typedef struct fts3Hash fts3Hash;

 typedef struct fts3HashElem fts3HashElem;

 /* A complete hash table is an instance of the following structure.

 ** The internals of this structure are intended to be opaque -- client

 ** code should not attempt to access or modify the fields of this structure

 ** directly.  Change this structure only by using the routines below.

 ** However, many of the "procedures" and "functions" for modifying and

 ** accessing this structure are really macros, so we can't really make

 ** this structure opaque.

 */

 struct fts3Hash {

   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 */

   fts3HashElem *first;    /* The first element of the array */

   int htsize;             /* Number of buckets in the hash table */

   struct _fts3ht {        /* the hash table */

     int count;               /* Number of entries with this hash */

     fts3HashElem *chain;     /* Pointer to first entry with this hash */

   } *ht;

 };

 /* Each element in the hash table is an instance of the following 

 ** structure.  All elements are stored on a single doubly-linked list.

 **

 ** Again, this structure is intended to be opaque, but it can't really

 ** be opaque because it is used by macros.

 */

 struct fts3HashElem {

   fts3HashElem *next, *prev; /* Next and previous elements in the table */

   void *data;                /* Data associated with this element */

   void *pKey; int nKey;      /* Key associated with this element */

 };

 /*

 ** There are 2 different modes of operation for a hash table:

 **

 **   FTS3_HASH_STRING        pKey points to a string that is nKey bytes long

 **                           (including the null-terminator, if any).  Case

 **                           is respected in comparisons.

 **

 **   FTS3_HASH_BINARY        pKey points to binary data nKey bytes long. 

 **                           memcmp() is used to compare keys.

 **

 ** A copy of the key is made if the copyKey parameter to fts3HashInit is 1.  

 */

 #define FTS3_HASH_STRING    1

 #define FTS3_HASH_BINARY    2

 /*

 ** Access routines.  To delete, insert a NULL pointer.

 */

 void sqlite3Fts3HashInit(fts3Hash*, int keytype, int copyKey);

 void *sqlite3Fts3HashInsert(fts3Hash*, const void *pKey, int nKey, void *pData);

 void *sqlite3Fts3HashFind(const fts3Hash*, const void *pKey, int nKey);

 void sqlite3Fts3HashClear(fts3Hash*);

 /*

 ** Shorthand for the functions above

 */

 #define fts3HashInit   sqlite3Fts3HashInit

 #define fts3HashInsert sqlite3Fts3HashInsert

 #define fts3HashFind   sqlite3Fts3HashFind

 #define fts3HashClear  sqlite3Fts3HashClear

 /*

 ** Macros for looping over all elements of a hash table.  The idiom is

 ** like this:

 **

 **   fts3Hash h;

 **   fts3HashElem *p;

 **   ...

 **   for(p=fts3HashFirst(&h); p; p=fts3HashNext(p)){

 **     SomeStructure *pData = fts3HashData(p);

 **     // do something with pData

 **   }

 */

 #define fts3HashFirst(H)  ((H)->first)

 #define fts3HashNext(E)   ((E)->next)

 #define fts3HashData(E)   ((E)->data)

 #define fts3HashKey(E)    ((E)->pKey)

 #define fts3HashKeysize(E) ((E)->nKey)

 /*

 ** Number of entries in a hash table

 */

 #define fts3HashCount(H)  ((H)->count)

 #endif /* _FTS3_HASH_H_ */