SQLite

  sqlite3_value **apVal           /* Array of trailing arguments */
){
  HighlightContext ctx;
  int rc = SQLITE_OK;             /* Return code */
  int iCol;                       /* 1st argument to snippet() */
  const char *zEllips;            /* 4th argument to snippet() */
  int nToken;                     /* 5th argument to snippet() */
  int nInst;                      /* Number of instance matches this row */
  int i;                          /* Used to iterate through instances */
  int nPhrase;                    /* Number of phrases in query */
  unsigned char *aSeen;           /* Array of "seen instance" flags */
  int iBestCol;                   /* Column containing best snippet */
  int iBestStart = 0;             /* First token of best snippet */
  int iBestLast;                  /* Last token of best snippet */
  int nBestScore = 0;             /* Score of best snippet */
  int nColSize;                   /* Total size of iBestCol in tokens */

  if( nVal!=5 ){
    const char *zErr = "wrong number of arguments to function snippet()";
    sqlite3_result_error(pCtx, zErr, -1);
    return;
  }

){
  int rc = SQLITE_OK;             /* Return code */
  Fts5Bm25Data *p;                /* Object to return */

  p = pApi->xGetAuxdata(pFts, 0);
  if( p==0 ){
    int nPhrase;                  /* Number of phrases in query */
    sqlite3_int64 nRow;           /* Number of rows in table */
    sqlite3_int64 nToken;         /* Number of tokens in table */
    int nByte;                    /* Bytes of space to allocate */
    int i;

    /* Allocate the Fts5Bm25Data object */
    nPhrase = pApi->xPhraseCount(pFts);
    nByte = sizeof(Fts5Bm25Data) + nPhrase*2*sizeof(double);
    p = (Fts5Bm25Data*)sqlite3_malloc(nByte);

){
  const double k1 = 1.2;          /* Constant "k1" from BM25 formula */
  const double b = 0.75;          /* Constant "b" from BM25 formula */
  int rc = SQLITE_OK;             /* Error code */
  double score = 0.0;             /* SQL function return value */
  Fts5Bm25Data *pData;            /* Values allocated/calculated once only */
  int i;                          /* Iterator variable */
  int nInst;                      /* Value returned by xInstCount() */
  double D;                       /* Total number of tokens in row */
  double *aFreq;                  /* Array of phrase freq. for current row */

  /* Calculate the phrase frequency (symbol "f(qi,D)" in the documentation)
  ** for each phrase in the query for the current row. */
  rc = fts5Bm25GetData(pApi, pFts, &pData);
  if( rc==SQLITE_OK ){
    aFreq = pData->aFreq;
    memset(aFreq, 0, sizeof(double) * pData->nPhrase);

    ** above returned SQLITE_ERROR, return SQLITE_CORRUPT_VTAB instead.
    ** All the reasons those functions might return SQLITE_ERROR - missing
    ** table, missing row, non-blob/text in block column - indicate 
    ** backing store corruption.  */
    if( rc==SQLITE_ERROR ) rc = FTS5_CORRUPT;

    if( rc==SQLITE_OK ){
      u8 *aOut;                   /* Read blob data into this buffer */
      int nByte = sqlite3_blob_bytes(p->pReader);
      if( pBuf ){
        fts5BufferSize(pBuf, MAX(nByte, p->pConfig->pgsz) + 20);
        pBuf->n = nByte;
        aOut = pBuf->p;
        if( aOut==0 ){
          rc = SQLITE_NOMEM;

  Fts5Index *p,                   /* FTS5 backend object */
  int iLvl,                       /* Index level just updated */
  Fts5Structure *pStruct          /* Index structure */
){
  if( p->rc==SQLITE_OK ){
    int iTst;
    int iPromote = -1;
    int szPromote;                /* Promote anything this size or smaller */
    Fts5StructureSegment *pSeg;   /* Segment just written */
    int szSeg;                    /* Size of segment just written */


    pSeg = &pStruct->aLevel[iLvl].aSeg[pStruct->aLevel[iLvl].nSeg-1];
    szSeg = (1 + pSeg->pgnoLast - pSeg->pgnoFirst);

            pIter->iLeafOffset += fts5GetVarint32(&a[iOff], nKeep);
          }
        }else{
          pIter->iRowid += iDelta;
        }
      }else if( pIter->pSeg==0 ){
        const u8 *pList = 0;
        const char *zTerm;
        int nList;
        if( 0==(pIter->flags & FTS5_SEGITER_ONETERM) ){
          sqlite3Fts5HashScanNext(p->pHash);
          sqlite3Fts5HashScanEntry(p->pHash, &zTerm, &pList, &nList);
        }
        if( pList==0 ){
          fts5DataRelease(pIter->pLeaf);
          pIter->pLeaf = 0;

    p->rc = FTS5_CORRUPT;
    return;
  }

  while( 1 ){
    int i;
    int nCmp;
    i64 rowid;

    /* Figure out how many new bytes are in this term */
    fts5IndexGetVarint32(a, iOff, nNew);

    if( nKeep<nMatch ){
      goto search_failed;
    }

  Fts5StructureSegment *pSeg,     /* Description of segment */
  Fts5SegIter *pIter              /* Object to populate */
){
  int iPg = 1;
  int h;
  int bGe = (flags & FTS5INDEX_QUERY_SCAN);
  int bDlidx = 0;                 /* True if there is a doclist-index */
  Fts5Data *pLeaf;

  static int nCall = 0;
  nCall++;

  assert( bGe==0 || (flags & FTS5INDEX_QUERY_DESC)==0 );
  assert( pTerm && nTerm );
  memset(pIter, 0, sizeof(*pIter));

  const char * const *argv,       /* xCreate/xConnect argument array */
  sqlite3_vtab **ppVTab,          /* Write the resulting vtab structure here */
  char **pzErr                    /* Write any error message here */
){
  Fts5Global *pGlobal = (Fts5Global*)pAux;
  const char **azConfig = (const char**)argv;
  int rc = SQLITE_OK;             /* Return code */
  Fts5Config *pConfig;            /* Results of parsing argc/argv */
  Fts5Table *pTab = 0;            /* New virtual table object */

  /* Allocate the new vtab object and parse the configuration */
  pTab = (Fts5Table*)sqlite3Fts5MallocZero(&rc, sizeof(Fts5Table));
  if( rc==SQLITE_OK ){
    rc = sqlite3Fts5ConfigParse(pGlobal, db, argc, azConfig, &pConfig, pzErr);
    assert( (rc==SQLITE_OK && *pzErr==0) || pConfig==0 );

**
** Return SQLITE_OK if nothing goes wrong.  SQLITE_OK is returned
** even if we reach end-of-file.  The fts5EofMethod() will be called
** subsequently to determine whether or not an EOF was hit.
*/
static int fts5NextMethod(sqlite3_vtab_cursor *pCursor){
  Fts5Cursor *pCsr = (Fts5Cursor*)pCursor;
  int rc;

  assert( (pCsr->ePlan<2)==
          (pCsr->ePlan==FTS5_PLAN_MATCH || pCsr->ePlan==FTS5_PLAN_SOURCE) 
  );

  if( pCsr->ePlan<2 ){
    int bSkip = 0;

/*
** Remove a row from the FTS table.
*/
int sqlite3Fts5StorageDelete(Fts5Storage *p, i64 iDel){
  Fts5Config *pConfig = p->pConfig;
  int rc;
  sqlite3_stmt *pDel;

  rc = fts5StorageLoadTotals(p, 1);

  /* Delete the index records */
  if( rc==SQLITE_OK ){
    rc = fts5StorageDeleteFromIndex(p, iDel);
  }

int sqlite3Fts5StorageSpecialDelete(
  Fts5Storage *p, 
  i64 iDel, 
  sqlite3_value **apVal
){
  Fts5Config *pConfig = p->pConfig;
  int rc;
  sqlite3_stmt *pDel;

  assert( pConfig->eContent!=FTS5_CONTENT_NORMAL );
  rc = fts5StorageLoadTotals(p, 1);

  /* Delete the index records */
  if( rc==SQLITE_OK ){
    int iCol;

  Fts5Storage *p,                 /* Storage module to write to */
  sqlite3_value **apVal,          /* Array of values passed to xUpdate() */
  int eConflict,                  /* on conflict clause */
  i64 *piRowid                    /* OUT: rowid of new record */
){
  Fts5Config *pConfig = p->pConfig;
  int rc = SQLITE_OK;             /* Return code */
  sqlite3_stmt *pInsert;          /* Statement used to write %_content table */
  int eStmt = 0;                  /* Type of statement used on %_content */
  int i;                          /* Counter variable */
  Fts5InsertCtx ctx;              /* Tokenization callback context object */
  Fts5Buffer buf;                 /* Buffer used to build up %_docsize blob */

  memset(&buf, 0, sizeof(Fts5Buffer));
  rc = fts5StorageLoadTotals(p, 1);

  u32 usableSize;          /* Usable size of the page */
  u32 contentOffset;       /* Offset to the start of the cell content area */
  u32 *heap = 0;           /* Min-heap used for checking cell coverage */
  u32 x, prev = 0;         /* Next and previous entry on the min-heap */
  const char *saved_zPfx = pCheck->zPfx;
  int saved_v1 = pCheck->v1;
  int saved_v2 = pCheck->v2;
  u8 savedIsInit;

  /* Check that the page exists
  */
  pBt = pCheck->pBt;
  usableSize = pBt->usableSize;
  if( iPage==0 ) return 0;
  if( checkRef(pCheck, iPage) ) return 0;