**
** Virtual table implementations may overload SQL functions by implementing
** the sqlite3_module.xFindFunction() method.
*/

typedef struct Fts5ExtensionApi Fts5ExtensionApi;
typedef struct Fts5Context Fts5Context;


typedef void (*fts5_extension_function)(
  const Fts5ExtensionApi *pApi,   /* API offered by current FTS version */
  Fts5Context *pFts,              /* First arg to pass to pApi functions */
  sqlite3_context *pCtx,          /* Context for returning result/error */
  int nVal,                       /* Number of values in apVal[] array */
  sqlite3_value **apVal           /* Array of trailing arguments */
);






/*
** EXTENSION API FUNCTIONS
**
** xUserData(pFts):
**   Return a copy of the context pointer the extension function was 
**   registered with.
................................................................................
**
** xRowCount(pFts5, pnRow)
**
**   This function is used to retrieve the total number of rows in the table.
**   In other words, the same value that would be returned by:
**
**        SELECT count(*) FROM ftstable;
























*/
struct Fts5ExtensionApi {
  int iVersion;                   /* Currently always set to 1 */

  void *(*xUserData)(Fts5Context*);

  int (*xColumnCount)(Fts5Context*);
................................................................................
  int (*xColumnSize)(Fts5Context*, int iCol, int *pnToken);

  int (*xQueryPhrase)(Fts5Context*, int iPhrase, void *pUserData,
    int(*)(const Fts5ExtensionApi*,Fts5Context*,void*)
  );
  int (*xSetAuxdata)(Fts5Context*, void *pAux, void(*xDelete)(void*));
  void *(*xGetAuxdata)(Fts5Context*, int bClear);



};

/* 
** CUSTOM AUXILIARY FUNCTIONS
*************************************************************************/

/*************************************************************************

**
** Virtual table implementations may overload SQL functions by implementing
** the sqlite3_module.xFindFunction() method.
*/

typedef struct Fts5ExtensionApi Fts5ExtensionApi;
typedef struct Fts5Context Fts5Context;
typedef struct Fts5PhraseIter Fts5PhraseIter;

typedef void (*fts5_extension_function)(
  const Fts5ExtensionApi *pApi,   /* API offered by current FTS version */
  Fts5Context *pFts,              /* First arg to pass to pApi functions */
  sqlite3_context *pCtx,          /* Context for returning result/error */
  int nVal,                       /* Number of values in apVal[] array */
  sqlite3_value **apVal           /* Array of trailing arguments */
);

struct Fts5PhraseIter {
  const unsigned char *a;
  const unsigned char *b;
};

/*
** EXTENSION API FUNCTIONS
**
** xUserData(pFts):
**   Return a copy of the context pointer the extension function was 
**   registered with.
................................................................................
**
** xRowCount(pFts5, pnRow)
**
**   This function is used to retrieve the total number of rows in the table.
**   In other words, the same value that would be returned by:
**
**        SELECT count(*) FROM ftstable;
**
** xPhraseFirst()
**   This function is used, along with type Fts5PhraseIter and the xPhraseNext
**   method, to iterate through all instances of a single query phrase within
**   the current row. This is the same information as is accessible via the
**   xInstCount/xInst APIs. While the xInstCount/xInst APIs are more convenient
**   to use, this API may be faster under some circumstances. To iterate 
**   through instances of phrase iPhrase, use the following code:
**
**       Fts5PhraseIter iter;
**       int iCol, iOff;
**       for(pApi->xPhraseFirst(pFts, iPhrase, &iter, &iCol, &iOff);
**           iOff>=0;
**           pApi->xPhraseNext(pFts, &iter, &iCol, &iOff)
**       ){
**         // An instance of phrase iPhrase at offset iOff of column iCol
**       }
**
**   The Fts5PhraseIter structure is defined above. Applications should not
**   modify this structure directly - it should only be used as shown above
**   with the xPhraseFirst() and xPhraseNext() API methods.
**
** xPhraseNext()
**   See xPhraseFirst above.
*/
struct Fts5ExtensionApi {
  int iVersion;                   /* Currently always set to 1 */

  void *(*xUserData)(Fts5Context*);

  int (*xColumnCount)(Fts5Context*);
................................................................................
  int (*xColumnSize)(Fts5Context*, int iCol, int *pnToken);

  int (*xQueryPhrase)(Fts5Context*, int iPhrase, void *pUserData,
    int(*)(const Fts5ExtensionApi*,Fts5Context*,void*)
  );
  int (*xSetAuxdata)(Fts5Context*, void *pAux, void(*xDelete)(void*));
  void *(*xGetAuxdata)(Fts5Context*, int bClear);

  void (*xPhraseFirst)(Fts5Context*, int iPhrase, Fts5PhraseIter*, int*, int*);
  void (*xPhraseNext)(Fts5Context*, Fts5PhraseIter*, int *piCol, int *piOff);
};

/* 
** CUSTOM AUXILIARY FUNCTIONS
*************************************************************************/

/*************************************************************************

  sqlite3_stmt *pRankArgStmt;     /* Origin of objects in apRankArg[] */

  /* Auxiliary data storage */
  Fts5Auxiliary *pAux;            /* Currently executing extension function */
  Fts5Auxdata *pAuxdata;          /* First in linked list of saved aux-data */

  /* Cache used by auxiliary functions xInst() and xInstCount() */


  int nInstCount;                 /* Number of phrase instances */
  int *aInst;                     /* 3 integers per phrase instance */
};

/*
** Bits that make up the "idxNum" parameter passed indirectly by 
** xBestIndex() to xFilter().
................................................................................
}

static void fts5FreeCursorComponents(Fts5Cursor *pCsr){
  Fts5Table *pTab = (Fts5Table*)(pCsr->base.pVtab);
  Fts5Auxdata *pData;
  Fts5Auxdata *pNext;


  sqlite3_free(pCsr->aInst);
  if( pCsr->pStmt ){
    int eStmt = fts5StmtType(pCsr);
    sqlite3Fts5StorageStmtRelease(pTab->pStorage, eStmt, pCsr->pStmt);
  }
  if( pCsr->pSorter ){
    Fts5Sorter *pSorter = pCsr->pSorter;
................................................................................
** SQLite error code otherwise.
*/
static int fts5CacheInstArray(Fts5Cursor *pCsr){
  int rc = SQLITE_OK;
  if( CsrFlagTest(pCsr, FTS5CSR_REQUIRE_INST) ){
    Fts5PoslistReader *aIter;     /* One iterator for each phrase */
    int nIter;                    /* Number of iterators/phrases */
    int nByte;
    
    nIter = sqlite3Fts5ExprPhraseCount(pCsr->pExpr);

    nByte = sizeof(Fts5PoslistReader) * nIter;
    aIter = (Fts5PoslistReader*)sqlite3Fts5MallocZero(&rc, nByte);



    if( aIter ){
      Fts5Buffer buf = {0, 0, 0}; /* Build up aInst[] here */
      int nInst = 0;              /* Number instances seen so far */
      int i;

      /* Initialize all iterators */
      for(i=0; i<nIter; i++){
        const u8 *a;
        int n = fts5CsrPoslist(pCsr, i, &a);
................................................................................
        for(i=0; i<nIter; i++){
          if( (aIter[i].bEof==0) 
           && (iBest<0 || aIter[i].iPos<aIter[iBest].iPos) 
          ){
            iBest = i;
          }
        }

        if( iBest<0 ) break;

        nInst++;
        if( sqlite3Fts5BufferGrow(&rc, &buf, nInst * sizeof(int) * 3) ) break;












        aInst = &((int*)buf.p)[3 * (nInst-1)];
        aInst[0] = iBest;
        aInst[1] = FTS5_POS2COLUMN(aIter[iBest].iPos);
        aInst[2] = FTS5_POS2OFFSET(aIter[iBest].iPos);
        sqlite3Fts5PoslistReaderNext(&aIter[iBest]);
      }

      sqlite3_free(pCsr->aInst);
      pCsr->aInst = (int*)buf.p;
      pCsr->nInstCount = nInst;
      sqlite3_free(aIter);
      CsrFlagClear(pCsr, FTS5CSR_REQUIRE_INST);
    }
  }
  return rc;
}

static int fts5ApiInstCount(Fts5Context *pCtx, int *pnInst){
................................................................................
      pData->pPtr = 0;
      pData->xDelete = 0;
    }
  }

  return pRet;
}




































static int fts5ApiQueryPhrase(Fts5Context*, int, void*, 
    int(*)(const Fts5ExtensionApi*, Fts5Context*, void*)
);

static const Fts5ExtensionApi sFts5Api = {
  1,                            /* iVersion */
  fts5ApiUserData,
  fts5ApiColumnCount,
  fts5ApiRowCount,
  fts5ApiColumnTotalSize,
  fts5ApiTokenize,
  fts5ApiPhraseCount,
  fts5ApiPhraseSize,
................................................................................
  fts5ApiInst,
  fts5ApiRowid,
  fts5ApiColumnText,
  fts5ApiColumnSize,
  fts5ApiQueryPhrase,
  fts5ApiSetAuxdata,
  fts5ApiGetAuxdata,


};


/*
** Implementation of API function xQueryPhrase().
*/
static int fts5ApiQueryPhrase(

  sqlite3_stmt *pRankArgStmt;     /* Origin of objects in apRankArg[] */

  /* Auxiliary data storage */
  Fts5Auxiliary *pAux;            /* Currently executing extension function */
  Fts5Auxdata *pAuxdata;          /* First in linked list of saved aux-data */

  /* Cache used by auxiliary functions xInst() and xInstCount() */
  Fts5PoslistReader *aInstIter;   /* One for each phrase */
  int nInstAlloc;                 /* Size of aInst[] array (entries / 3) */
  int nInstCount;                 /* Number of phrase instances */
  int *aInst;                     /* 3 integers per phrase instance */
};

/*
** Bits that make up the "idxNum" parameter passed indirectly by 
** xBestIndex() to xFilter().
................................................................................
}

static void fts5FreeCursorComponents(Fts5Cursor *pCsr){
  Fts5Table *pTab = (Fts5Table*)(pCsr->base.pVtab);
  Fts5Auxdata *pData;
  Fts5Auxdata *pNext;

  sqlite3_free(pCsr->aInstIter);
  sqlite3_free(pCsr->aInst);
  if( pCsr->pStmt ){
    int eStmt = fts5StmtType(pCsr);
    sqlite3Fts5StorageStmtRelease(pTab->pStorage, eStmt, pCsr->pStmt);
  }
  if( pCsr->pSorter ){
    Fts5Sorter *pSorter = pCsr->pSorter;
................................................................................
** SQLite error code otherwise.
*/
static int fts5CacheInstArray(Fts5Cursor *pCsr){
  int rc = SQLITE_OK;
  if( CsrFlagTest(pCsr, FTS5CSR_REQUIRE_INST) ){
    Fts5PoslistReader *aIter;     /* One iterator for each phrase */
    int nIter;                    /* Number of iterators/phrases */

    
    nIter = sqlite3Fts5ExprPhraseCount(pCsr->pExpr);
    if( pCsr->aInstIter==0 ){
      int nByte = sizeof(Fts5PoslistReader) * nIter;
      pCsr->aInstIter = (Fts5PoslistReader*)sqlite3Fts5MallocZero(&rc, nByte);
    }
    aIter = pCsr->aInstIter;

    if( aIter ){

      int nInst = 0;              /* Number instances seen so far */
      int i;

      /* Initialize all iterators */
      for(i=0; i<nIter; i++){
        const u8 *a;
        int n = fts5CsrPoslist(pCsr, i, &a);
................................................................................
        for(i=0; i<nIter; i++){
          if( (aIter[i].bEof==0) 
           && (iBest<0 || aIter[i].iPos<aIter[iBest].iPos) 
          ){
            iBest = i;
          }
        }

        if( iBest<0 ) break;

        nInst++;
        if( nInst>=pCsr->nInstAlloc ){
          pCsr->nInstAlloc = pCsr->nInstAlloc ? pCsr->nInstAlloc*2 : 32;
          aInst = (int*)sqlite3_realloc(
              pCsr->aInst, pCsr->nInstAlloc*sizeof(int)*3
          );
          if( aInst ){
            pCsr->aInst = aInst;
          }else{
            rc = SQLITE_NOMEM;
            break;
          }
        }

        aInst = &pCsr->aInst[3 * (nInst-1)];
        aInst[0] = iBest;
        aInst[1] = FTS5_POS2COLUMN(aIter[iBest].iPos);
        aInst[2] = FTS5_POS2OFFSET(aIter[iBest].iPos);
        sqlite3Fts5PoslistReaderNext(&aIter[iBest]);
      }



      pCsr->nInstCount = nInst;

      CsrFlagClear(pCsr, FTS5CSR_REQUIRE_INST);
    }
  }
  return rc;
}

static int fts5ApiInstCount(Fts5Context *pCtx, int *pnInst){
................................................................................
      pData->pPtr = 0;
      pData->xDelete = 0;
    }
  }

  return pRet;
}

static void fts5ApiPhraseNext(
  Fts5Context *pCtx, 
  Fts5PhraseIter *pIter, 
  int *piCol, int *piOff
){
  if( pIter->a>=pIter->b ){
    *piCol = -1;
    *piOff = -1;
  }else{
    int iVal;
    pIter->a += fts5GetVarint32(pIter->a, iVal);
    if( iVal==1 ){
      pIter->a += fts5GetVarint32(pIter->a, iVal);
      *piCol = iVal;
      *piOff = 0;
      pIter->a += fts5GetVarint32(pIter->a, iVal);
    }
    *piOff += (iVal-2);
  }
}

static void fts5ApiPhraseFirst(
  Fts5Context *pCtx, 
  int iPhrase, 
  Fts5PhraseIter *pIter, 
  int *piCol, int *piOff
){
  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
  int n = fts5CsrPoslist(pCsr, iPhrase, &pIter->a);
  pIter->b = &pIter->a[n];
  *piCol = 0;
  *piOff = 0;
  fts5ApiPhraseNext(pCtx, pIter, piCol, piOff);
}

static int fts5ApiQueryPhrase(Fts5Context*, int, void*, 
    int(*)(const Fts5ExtensionApi*, Fts5Context*, void*)
);

static const Fts5ExtensionApi sFts5Api = {
  2,                            /* iVersion */
  fts5ApiUserData,
  fts5ApiColumnCount,
  fts5ApiRowCount,
  fts5ApiColumnTotalSize,
  fts5ApiTokenize,
  fts5ApiPhraseCount,
  fts5ApiPhraseSize,
................................................................................
  fts5ApiInst,
  fts5ApiRowid,
  fts5ApiColumnText,
  fts5ApiColumnSize,
  fts5ApiQueryPhrase,
  fts5ApiSetAuxdata,
  fts5ApiGetAuxdata,
  fts5ApiPhraseFirst,
  fts5ApiPhraseNext,
};


/*
** Implementation of API function xQueryPhrase().
*/
static int fts5ApiQueryPhrase(

}

static int fts5MatchinfoXCb(
  const Fts5ExtensionApi *pApi,
  Fts5Context *pFts,
  void *pUserData
){


  u32 *aOut = (u32*)pUserData;
  int nCol = pApi->xColumnCount(pFts);
  int nInst;
  int iPrev = -1;
  int rc;
  int i;



  rc = pApi->xInstCount(pFts, &nInst);
  for(i=0; rc==SQLITE_OK && i<nInst; i++){
    int iPhrase, iCol, iOff;
    rc = pApi->xInst(pFts, i, &iPhrase, &iCol, &iOff);
    aOut[iCol*3 + 1]++;
    if( iCol!=iPrev ) aOut[iCol*3 + 2]++;
    iPrev = iCol;
  }

  return rc;
}

static int fts5MatchinfoGlobalCb(
  const Fts5ExtensionApi *pApi,
  Fts5Context *pFts,
  Fts5MatchinfoCtx *p,
  char f,
................................................................................
  int i;
  int rc = SQLITE_OK;

  switch( f ){
    case 'b': 
    case 'x':
    case 'y': {
      int nInst;
      int nMul = (f=='x' ? 3 : 1);


      if( f=='b' ){
        int nInt = ((p->nCol + 31) / 32) * p->nPhrase;
        for(i=0; i<nInt; i++) aOut[i] = 0;
      }else{
        for(i=0; i<(p->nCol*p->nPhrase); i++) aOut[i*nMul] = 0;
      }

      rc = pApi->xInstCount(pFts, &nInst);
      for(i=0; rc==SQLITE_OK && i<nInst; i++){
        int iPhrase, iOff, iCol = 0;
        rc = pApi->xInst(pFts, i, &iPhrase, &iCol, &iOff);



        if( f=='b' ){
          aOut[iPhrase * ((p->nCol+31)/32) + iCol/32] |= ((u32)1 << (iCol%32));
        }else{
          aOut[nMul * (iCol + iPhrase * p->nCol)]++;

        }
      }

      break;
    }

    case 'l': {
................................................................................
  ** fts5_api_from_db() function above is copied verbatim from the 
  ** FTS5 documentation. Refer there for details. */
  pApi = fts5_api_from_db(db);

  /* If fts5_api_from_db() returns NULL, then either FTS5 is not registered
  ** with this database handle, or an error (OOM perhaps?) has occurred.
  **
  ** Also check that the fts5_api object is version 1 or newer (there 
  ** is no actual version of FTS5 that would return an API object of version
  ** 0, but FTS5 extensions should check the API version before using it). */
  if( pApi==0 || pApi->iVersion<1 ){
    return SQLITE_ERROR;
  }

  /* Register the implementation of matchinfo() */
  rc = pApi->xCreateFunction(pApi, "matchinfo", 0, fts5MatchinfoFunc, 0);

  return rc;
}

#endif /* SQLITE_ENABLE_FTS5 */
#endif /* SQLITE_TEST */

}

static int fts5MatchinfoXCb(
  const Fts5ExtensionApi *pApi,
  Fts5Context *pFts,
  void *pUserData
){
  Fts5PhraseIter iter;
  int iCol, iOff;
  u32 *aOut = (u32*)pUserData;


  int iPrev = -1;



  for(pApi->xPhraseFirst(pFts, 0, &iter, &iCol, &iOff); 
      iOff>=0; 
      pApi->xPhraseNext(pFts, &iter, &iCol, &iOff)
  ){


    aOut[iCol*3+1]++;
    if( iCol!=iPrev ) aOut[iCol*3 + 2]++;
    iPrev = iCol;
  }

  return SQLITE_OK;
}

static int fts5MatchinfoGlobalCb(
  const Fts5ExtensionApi *pApi,
  Fts5Context *pFts,
  Fts5MatchinfoCtx *p,
  char f,
................................................................................
  int i;
  int rc = SQLITE_OK;

  switch( f ){
    case 'b': 
    case 'x':
    case 'y': {

      int nMul = (f=='x' ? 3 : 1);
      int iPhrase;

      if( f=='b' ){
        int nInt = ((p->nCol + 31) / 32) * p->nPhrase;
        for(i=0; i<nInt; i++) aOut[i] = 0;
      }else{
        for(i=0; i<(p->nCol*p->nPhrase); i++) aOut[i*nMul] = 0;
      }

      for(iPhrase=0; iPhrase<p->nPhrase; iPhrase++){
        Fts5PhraseIter iter;
        int iOff, iCol;
        for(pApi->xPhraseFirst(pFts, iPhrase, &iter, &iCol, &iOff); 
            iOff>=0; 
            pApi->xPhraseNext(pFts, &iter, &iCol, &iOff)
        ){
          if( f=='b' ){
            aOut[iPhrase * ((p->nCol+31)/32) + iCol/32] |= ((u32)1 << iCol%32);
          }else{
            aOut[nMul * (iCol + iPhrase * p->nCol)]++;
          }
        }
      }

      break;
    }

    case 'l': {
................................................................................
  ** fts5_api_from_db() function above is copied verbatim from the 
  ** FTS5 documentation. Refer there for details. */
  pApi = fts5_api_from_db(db);

  /* If fts5_api_from_db() returns NULL, then either FTS5 is not registered
  ** with this database handle, or an error (OOM perhaps?) has occurred.
  **
  ** Also check that the fts5_api object is version 2 or newer.  
  */ 

  if( pApi==0 || pApi->iVersion<1 ){
    return SQLITE_ERROR;
  }

  /* Register the implementation of matchinfo() */
  rc = pApi->xCreateFunction(pApi, "matchinfo", 0, fts5MatchinfoFunc, 0);

  return rc;
}

#endif /* SQLITE_ENABLE_FTS5 */
#endif /* SQLITE_TEST */