/*

** 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_ */