SQLite

  fts3Appendf(pRc, &zRet, "?");
  for(i=0; i<p->nColumn; i++){
    fts3Appendf(pRc, &zRet, ",%s(?)", zFunction);
  }
  sqlite3_free(zFree);
  return zRet;
}

static int fts3GobbleInt(const char **pp, int *pnOut){
  const char *p = *pp;
  int nInt = 0;
  for(p=*pp; p[0]>='0' && p[0]<='9'; p++){
    nInt = nInt * 10 + (p[0] - '0');
  }
  if( p==*pp ) return SQLITE_ERROR;
  *pnOut = nInt;
  *pp = p;
  return SQLITE_OK;
}


static int fts3PrefixParameter(
  const char *zParam,             /* ABC in prefix=ABC parameter to parse */
  int *pnIndex,                   /* OUT: size of *apIndex[] array */
  struct Fts3Index **apIndex,     /* OUT: Array of indexes for this table */
  struct Fts3Index **apFree       /* OUT: Free this with sqlite3_free() */
){
  struct Fts3Index *aIndex;
  int nIndex = 1;

  if( zParam && zParam[0] ){
    const char *p;
    nIndex++;
    for(p=zParam; *p; p++){
      if( *p==',' ) nIndex++;
    }
  }

  aIndex = sqlite3_malloc(sizeof(struct Fts3Index) * nIndex);
  *apIndex = *apFree = aIndex;
  *pnIndex = nIndex;
  if( !aIndex ){
    return SQLITE_NOMEM;
  }

  memset(aIndex, 0, sizeof(struct Fts3Index) * nIndex);
  if( zParam ){
    const char *p = zParam;
    int i;
    for(i=1; i<nIndex; i++){
      int nPrefix;
      if( fts3GobbleInt(&p, &nPrefix) ) return SQLITE_ERROR;
      aIndex[i].nPrefix = nPrefix;
      p++;
    }
  }

  return SQLITE_OK;
}

/*
** This function is the implementation of both the xConnect and xCreate
** methods of the FTS3 virtual table.
**
** The argv[] array contains the following:
**

  int nString = 0;                /* Bytes required to hold all column names */
  int nCol = 0;                   /* Number of columns in the FTS table */
  char *zCsr;                     /* Space for holding column names */
  int nDb;                        /* Bytes required to hold database name */
  int nName;                      /* Bytes required to hold table name */
  int isFts4 = (argv[0][3]=='4'); /* True for FTS4, false for FTS3 */
  int bNoDocsize = 0;             /* True to omit %_docsize table */
  int bPrefix = 0;                /* True to include a prefix-search index */
  const char **aCol;              /* Array of column names */
  sqlite3_tokenizer *pTokenizer = 0;        /* Tokenizer for this table */

  char *zPrefix = 0;              /* Prefix parameter value (or NULL) */
  int nIndex;                     /* Size of aIndex[] array */
  struct Fts3Index *aIndex;       /* Array of indexes for this table */
  struct Fts3Index *aFree = 0;    /* Free this before returning */

  char *zCompress = 0;
  char *zUncompress = 0;

  assert( strlen(argv[0])==4 );
  assert( (sqlite3_strnicmp(argv[0], "fts4", 4)==0 && isFts4)
       || (sqlite3_strnicmp(argv[0], "fts3", 4)==0 && !isFts4)

      }else if( nKey==8 && 0==sqlite3_strnicmp(z, "compress", 8) ){
        zCompress = zVal;
        zVal = 0;
      }else if( nKey==10 && 0==sqlite3_strnicmp(z, "uncompress", 10) ){
        zUncompress = zVal;
        zVal = 0;
      }else if( nKey==6 && 0==sqlite3_strnicmp(z, "prefix", 6) ){
        sqlite3_free(zPrefix);
        bPrefix = 1;
        zPrefix = zVal;
        zVal = 0;
      }else{
        *pzErr = sqlite3_mprintf("unrecognized parameter: %s", z);
        rc = SQLITE_ERROR;
      }
      sqlite3_free(zVal);
    }

  if( pTokenizer==0 ){
    rc = sqlite3Fts3InitTokenizer(pHash, "simple", &pTokenizer, pzErr);
    if( rc!=SQLITE_OK ) goto fts3_init_out;
  }
  assert( pTokenizer );

  rc = fts3PrefixParameter(zPrefix, &nIndex, &aIndex, &aFree);
  if( rc==SQLITE_ERROR ){
    assert( zPrefix );
    *pzErr = sqlite3_mprintf("error parsing prefix parameter: %s", zPrefix);

  }
  if( rc ) goto fts3_init_out;


  /* Allocate and populate the Fts3Table structure. */
  nByte = sizeof(Fts3Table) +              /* Fts3Table */
  nByte = sizeof(Fts3Table) +                  /* Fts3Table */
          nCol * sizeof(char *) +              /* azColumn */
          nIndex * sizeof(struct Fts3Index) +  /* aIndex */
          nName +                              /* zName */
          nDb +                                /* zDb */
          nString;                             /* Space for azColumn strings */
  p = (Fts3Table*)sqlite3_malloc(nByte);
  if( p==0 ){
    rc = SQLITE_NOMEM;
    goto fts3_init_out;
  }
  memset(p, 0, nByte);
  p->db = db;
  p->nColumn = nCol;
  p->nPendingData = 0;
  p->azColumn = (char **)&p[1];
  p->pTokenizer = pTokenizer;
  p->nNodeSize = 1000;
  p->nMaxPendingData = FTS3_MAX_PENDING_DATA;
  p->bHasDocsize = (isFts4 && bNoDocsize==0);
  p->bHasStat = isFts4;
  TESTONLY( p->inTransaction = -1 );
  TESTONLY( p->mxSavepoint = -1 );
  p->bPrefix = bPrefix;
  fts3HashInit(&p->pendingTerms, FTS3_HASH_STRING, 1);
  fts3HashInit(&p->pendingPrefixes, FTS3_HASH_STRING, 1);


  p->aIndex = (struct Fts3Index *)&p->azColumn[nCol];
  memcpy(p->aIndex, aIndex, sizeof(struct Fts3Index) * nIndex);
  p->nIndex = nIndex;
  for(i=0; i<nIndex; i++){
    fts3HashInit(&p->aIndex[i].hPending, FTS3_HASH_STRING, 1);
  }

  /* Fill in the zName and zDb fields of the vtab structure. */
  zCsr = (char *)&p->azColumn[nCol];
  zCsr = (char *)&p->aIndex[nIndex];
  p->zName = zCsr;
  memcpy(zCsr, argv[2], nName);
  zCsr += nName;
  p->zDb = zCsr;
  memcpy(zCsr, argv[1], nDb);
  zCsr += nDb;

  */
  fts3DatabasePageSize(&rc, p);

  /* Declare the table schema to SQLite. */
  fts3DeclareVtab(&rc, p);

fts3_init_out:
  sqlite3_free(zPrefix);
  sqlite3_free(aFree);
  sqlite3_free(zCompress);
  sqlite3_free(zUncompress);
  sqlite3_free((void *)aCol);
  if( rc!=SQLITE_OK ){
    if( p ){
      fts3DisconnectMethod((sqlite3_vtab *)p);
    }else if( pTokenizer ){

    if( !*ppOut ) return SQLITE_NOMEM;
    sqlite3Fts3PutVarint(*ppOut, docid);
  }

  return SQLITE_OK;
}

/*
** Append SegReader object pNew to the end of the pCsr->apSegment[] array.
*/
static int fts3SegReaderCursorAppend(
  Fts3SegReaderCursor *pCsr, 
  Fts3SegReader *pNew
){
  if( (pCsr->nSegment%16)==0 ){
    Fts3SegReader **apNew;
    int nByte = (pCsr->nSegment + 16)*sizeof(Fts3SegReader*);
    apNew = (Fts3SegReader **)sqlite3_realloc(pCsr->apSegment, nByte);
    if( !apNew ){
      sqlite3Fts3SegReaderFree(pNew);
      return SQLITE_NOMEM;
    }
    pCsr->apSegment = apNew;
  }
  pCsr->apSegment[pCsr->nSegment++] = pNew;
  return SQLITE_OK;
}

/*
** Set up a cursor object for iterating through the full-text index or 
** a single level therein.
** Set up a cursor object for iterating through a full-text index or a 
** single level therein.
*/
int sqlite3Fts3SegReaderCursor(
  Fts3Table *p,                   /* FTS3 table handle */
  int iIndex,                     /* Index to search (from 0 to p->nIndex-1) */
  int iLevel,                     /* Level of segments to scan */
  const char *zTerm,              /* Term to query for */
  int nTerm,                      /* Size of zTerm in bytes */
  int isPrefix,                   /* True for a prefix search */
  int isScan,                     /* True to scan from zTerm to EOF */
  Fts3SegReaderCursor *pCsr       /* Cursor object to populate */
){
  int rc = SQLITE_OK;
  int rc2;
  int iAge = 0;
  sqlite3_stmt *pStmt = 0;

  assert( iIndex>=0 && iIndex<p->nIndex );
  assert( iLevel==FTS3_SEGCURSOR_ALL_TERM
  assert( iLevel==FTS3_SEGCURSOR_ALL
      ||  iLevel==FTS3_SEGCURSOR_PENDING 
      ||  iLevel==FTS3_SEGCURSOR_PENDING_PREFIX
      ||  iLevel==FTS3_SEGCURSOR_ALL_PREFIX
      ||  iLevel>=0
  );
  assert( 0>FTS3_SEGCURSOR_ALL_TERM
      &&  0>FTS3_SEGCURSOR_PENDING 
  assert( iLevel<FTS3_SEGDIR_MAXLEVEL );
  assert( FTS3_SEGCURSOR_ALL<0 && FTS3_SEGCURSOR_PENDING<0 );
      &&  0>FTS3_SEGCURSOR_PENDING_PREFIX
      &&  0>FTS3_SEGCURSOR_ALL_PREFIX
  );
  assert( iLevel==FTS3_SEGCURSOR_ALL_TERM
  assert( iLevel==FTS3_SEGCURSOR_ALL || (zTerm==0 && isPrefix==1) );
       || iLevel==FTS3_SEGCURSOR_ALL_PREFIX 
       || (zTerm==0 && isPrefix==1) 
  );
  assert( isPrefix==0 || isScan==0 );

  memset(pCsr, 0, sizeof(Fts3SegReaderCursor));

  /* "isScan" is only set to true by the ft4aux module, not an ordinary
  ** full-text table. The pendingTerms and pendingPrefixes tables must be
  /* "isScan" is only set to true by the ft4aux module, an ordinary
  ** full-text tables. */
  ** empty in this case. */
  assert( isScan==0 || fts3HashCount(&p->pendingTerms)==0 );
  assert( isScan==0 || fts3HashCount(&p->pendingPrefixes)==0 );
  assert( isScan==0 || p->aIndex==0 );

  memset(pCsr, 0, sizeof(Fts3SegReaderCursor));

  /* If iLevel is less than 0, include a seg-reader for the pending-terms. */
  if( iLevel<0 && isScan==0 ){
  /* If iLevel is less than 0 and this is not a scan, include a seg-reader 
  ** for the pending-terms. If this is a scan, then this call must be being
  ** made by an fts4aux module, not an FTS table. In this case calling
  ** Fts3SegReaderPending might segfault, as the data structures used by 
  ** fts4aux are not completely populated. So it's easiest to filter these
  ** calls out here.  */
  if( iLevel<0 && p->aIndex ){
    int bPrefix = (
        iLevel==FTS3_SEGCURSOR_PENDING_PREFIX 
     || iLevel==FTS3_SEGCURSOR_ALL_PREFIX
    );
    Fts3SegReader *pPending = 0;
    Fts3SegReader *pSeg = 0;

    rc = sqlite3Fts3SegReaderPending(p,zTerm,nTerm,isPrefix,bPrefix,&pPending);
    if( rc==SQLITE_OK && pPending ){
      rc = fts3SegReaderCursorAppend(pCsr, pPending);
    rc = sqlite3Fts3SegReaderPending(p, iIndex, zTerm, nTerm, isPrefix, &pSeg);
    if( rc==SQLITE_OK && pSeg ){
      rc = fts3SegReaderCursorAppend(pCsr, pSeg);
    }
  }

  if( iLevel!=FTS3_SEGCURSOR_PENDING && iLevel!=FTS3_SEGCURSOR_PENDING_PREFIX ){
  if( iLevel!=FTS3_SEGCURSOR_PENDING ){
    if( rc==SQLITE_OK ){
      rc = sqlite3Fts3AllSegdirs(p, iLevel, &pStmt);
      rc = sqlite3Fts3AllSegdirs(p, iIndex, iLevel, &pStmt);
    }

    while( rc==SQLITE_OK && SQLITE_ROW==(rc = sqlite3_step(pStmt)) ){
      Fts3SegReader *pSeg = 0;

      /* Read the values returned by the SELECT into local variables. */
      sqlite3_int64 iStartBlock = sqlite3_column_int64(pStmt, 1);
      sqlite3_int64 iLeavesEndBlock = sqlite3_column_int64(pStmt, 2);
      sqlite3_int64 iEndBlock = sqlite3_column_int64(pStmt, 3);

  Fts3SegReaderCursor *pSegcsr;   /* Object to allocate and return */
  int rc = SQLITE_NOMEM;          /* Return code */

  pSegcsr = sqlite3_malloc(sizeof(Fts3SegReaderCursor));
  if( pSegcsr ){
    int i;
    int nCost = 0;
    int bFound = 0;               /* True once an index has been found */
    Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;

    if( isPrefix && p->bPrefix && nTerm<=FTS3_MAX_PREFIX ){
      rc = sqlite3Fts3SegReaderCursor(
          p, FTS3_SEGCURSOR_ALL_PREFIX, zTerm, nTerm, 0, 0, pSegcsr);

    }else{
    if( isPrefix ){
      for(i=1; i<p->nIndex; i++){
        if( p->aIndex[i].nPrefix==nTerm ){
          bFound = 1;
          rc = sqlite3Fts3SegReaderCursor(
              p, i, FTS3_SEGCURSOR_ALL, zTerm, nTerm, 0, 0, pSegcsr);
          break;
        }
      }
    }

    if( bFound==0 ){
      rc = sqlite3Fts3SegReaderCursor(
          p, FTS3_SEGCURSOR_ALL_TERM, zTerm, nTerm, isPrefix, 0, pSegcsr);
          p, 0, FTS3_SEGCURSOR_ALL, zTerm, nTerm, isPrefix, 0, pSegcsr
      );
    }
  
    for(i=0; rc==SQLITE_OK && i<pSegcsr->nSegment; i++){
      rc = sqlite3Fts3SegReaderCost(pCsr, pSegcsr->apSegment[i], &nCost);
    }
    pSegcsr->nCost = nCost;
  }

  *ppSegcsr = pSegcsr;

*/
static int fts3RollbackMethod(sqlite3_vtab *pVtab){
  Fts3Table *p = (Fts3Table*)pVtab;
  sqlite3Fts3PendingTermsClear(p);
  assert( p->inTransaction!=0 );
  TESTONLY( p->inTransaction = 0 );
  TESTONLY( p->mxSavepoint = -1; );
  sqlite3Fts3PendingPrefixesClear((Fts3Table *)pVtab);
  return SQLITE_OK;
}

/*
** Load the doclist associated with expression pExpr to pExpr->aDoclist.
** The loaded doclist contains positions as well as the document ids.
** This is used by the matchinfo(), snippet() and offsets() auxillary

}
static int fts3RollbackToMethod(sqlite3_vtab *pVtab, int iSavepoint){
  Fts3Table *p = (Fts3Table*)pVtab;
  assert( p->inTransaction );
  assert( p->mxSavepoint >= iSavepoint );
  TESTONLY( p->mxSavepoint = iSavepoint );
  sqlite3Fts3PendingTermsClear(p);
  sqlite3Fts3PendingPrefixesClear((Fts3Table *)pVtab);
  return SQLITE_OK;
}

static const sqlite3_module fts3Module = {
  /* iVersion      */ 2,
  /* xCreate       */ fts3CreateMethod,
  /* xConnect      */ fts3ConnectMethod,

# define NDEBUG 1
#endif

#include "sqlite3.h"
#include "fts3_tokenizer.h"
#include "fts3_hash.h"

#define FTS3_MAX_PREFIX 8

/*
** This constant controls how often segments are merged. Once there are
** FTS3_MERGE_COUNT segments of level N, they are merged into a single
** segment of level N+1.
*/
#define FTS3_MERGE_COUNT 16

/*
** Maximum length of a varint encoded integer. The varint format is different
** from that used by SQLite, so the maximum length is 10, not 9.
*/
#define FTS3_VARINT_MAX 10

/*
** FTS4 virtual tables may maintain two separate indexes. One that indexes
** FTS4 virtual tables may maintain multiple indexes - one index of all terms
** all document terms (the same index FTS3 tables maintain) and another used
** for prefixes. B+-trees that are part of the prefix index have values for
** the %_segdir.level column that are equal to or greater than the following
** value.
** in the document set and zero or more prefix indexes. All indexes are stored
** as one or more b+-trees in the %_segments and %_segdir tables. 
**
** It is possible to determine which index a b+-tree belongs to based on the
** value stored in the "%_segdir.level" column. Given this value L, the index
** that the b+-tree belongs to is (L<<10). In other words, all b+-trees with
** level values between 0 and 1023 (inclusive) belong to index 0, all levels
** between 1024 and 2047 to index 1, and so on.
**
** It is considered impossible for the regular index to use levels this large.
** In theory it could, but that would require that at least 2^1024 separate
** write operations to be made within the lifetime of the database.
** It is considered impossible for an index to use more than 1024 levels. In 
** theory though this may happen, but only after at least 
** (FTS3_MERGE_COUNT^1024) separate flushes of the pending-terms tables.
*/
#define FTS3_SEGDIR_PREFIXLEVEL 1024
#define FTS3_SEGDIR_PREFIXLEVEL_STR "1024"
#define FTS3_SEGDIR_MAXLEVEL      1024
#define FTS3_SEGDIR_MAXLEVEL_STR "1024"

/*
** The testcase() macro is only used by the amalgamation.  If undefined,
** make it a no-op.
*/
#ifndef testcase
# define testcase(X)

  char *zReadExprlist;
  char *zWriteExprlist;

  int nNodeSize;                  /* Soft limit for node size */
  u8 bHasStat;                    /* True if %_stat table exists */
  u8 bHasDocsize;                 /* True if %_docsize table exists */
  u8 bPrefix;                     /* True if there is a prefix index */
  int nPgsz;                      /* Page size for host database */
  char *zSegmentsTbl;             /* Name of %_segments table */
  sqlite3_blob *pSegments;        /* Blob handle open on %_segments table */

  /* TODO: Fix the first paragraph of this comment.
  **
  /* The following hash table is used to buffer pending index updates during
  ** The following hash table is used to buffer pending index updates during
  ** transactions. Variable nPendingData estimates the memory size of the 
  ** pending data, including hash table overhead, but not malloc overhead. 
  ** When nPendingData exceeds nMaxPendingData, the buffer is flushed 
  ** automatically. Variable iPrevDocid is the docid of the most recently
  ** inserted record.
  **
  ** A single FTS4 table may have multiple full-text indexes. For each index
  ** there is an entry in the aIndex[] array. Index 0 is an index of all the
  ** terms that appear in the document set. Each subsequent index in aIndex[]
  ** is an index of prefixes of a specific length.
  */
  int nIndex;                     /* Size of aIndex[] */
  struct Fts3Index {
    int nPrefix;                  /* Prefix length (0 for main terms index) */
    Fts3Hash hPending;            /* Pending terms table for this index */
  } *aIndex;
  int nMaxPendingData;
  int nPendingData;
  sqlite_int64 iPrevDocid;
  int nMaxPendingData;            /* Max pending data before flush to disk */
  int nPendingData;               /* Current bytes of pending data */
  sqlite_int64 iPrevDocid;        /* Docid of most recently inserted document */
  Fts3Hash pendingTerms;
  Fts3Hash pendingPrefixes;

#if defined(SQLITE_DEBUG)
  /* State variables used for validating that the transaction control
  ** methods of the virtual table are called at appropriate times.  These
  ** values do not contribution to the FTS computation; they are used for
  ** verifying the SQLite core.
  */

int sqlite3Fts3UpdateMethod(sqlite3_vtab*,int,sqlite3_value**,sqlite3_int64*);
int sqlite3Fts3PendingTermsFlush(Fts3Table *);
void sqlite3Fts3PendingTermsClear(Fts3Table *);
int sqlite3Fts3Optimize(Fts3Table *);
int sqlite3Fts3SegReaderNew(int, sqlite3_int64,
  sqlite3_int64, sqlite3_int64, const char *, int, Fts3SegReader**);
int sqlite3Fts3SegReaderPending(
  Fts3Table*,const char*,int,int,int,Fts3SegReader**);
  Fts3Table*,int,const char*,int,int,Fts3SegReader**);
void sqlite3Fts3SegReaderFree(Fts3SegReader *);
int sqlite3Fts3SegReaderCost(Fts3Cursor *, Fts3SegReader *, int *);
int sqlite3Fts3AllSegdirs(Fts3Table*, int, sqlite3_stmt **);
int sqlite3Fts3AllSegdirs(Fts3Table*, int, int, sqlite3_stmt **);
int sqlite3Fts3ReadLock(Fts3Table *);
int sqlite3Fts3ReadBlock(Fts3Table*, sqlite3_int64, char **, int*);

int sqlite3Fts3SelectDoctotal(Fts3Table *, sqlite3_stmt **);
int sqlite3Fts3SelectDocsize(Fts3Table *, sqlite3_int64, sqlite3_stmt **);

void sqlite3Fts3FreeDeferredTokens(Fts3Cursor *);
int sqlite3Fts3DeferToken(Fts3Cursor *, Fts3PhraseToken *, int);
int sqlite3Fts3CacheDeferredDoclists(Fts3Cursor *);
void sqlite3Fts3FreeDeferredDoclists(Fts3Cursor *);
char *sqlite3Fts3DeferredDoclist(Fts3DeferredToken *, int *);
void sqlite3Fts3SegmentsClose(Fts3Table *);

/* Special values interpreted by sqlite3SegReaderCursor() */
#define FTS3_SEGCURSOR_PENDING        -1
#define FTS3_SEGCURSOR_PENDING_PREFIX -2
#define FTS3_SEGCURSOR_ALL_PREFIX     -3
#define FTS3_SEGCURSOR_ALL            -2
#define FTS3_SEGCURSOR_ALL_TERM       -4

int sqlite3Fts3SegReaderStart(Fts3Table*, Fts3SegReaderCursor*, Fts3SegFilter*);
int sqlite3Fts3SegReaderStep(Fts3Table *, Fts3SegReaderCursor *);
void sqlite3Fts3SegReaderFinish(Fts3SegReaderCursor *);
int sqlite3Fts3SegReaderCursor(
    Fts3Table *, int, const char *, int, int, int, Fts3SegReaderCursor *);
    Fts3Table *, int, int, const char *, int, int, int, Fts3SegReaderCursor *);

/* Flags allowed as part of the 4th argument to SegmentReaderIterate() */
#define FTS3_SEGMENT_REQUIRE_POS   0x00000001
#define FTS3_SEGMENT_IGNORE_EMPTY  0x00000002
#define FTS3_SEGMENT_COLUMN_FILTER 0x00000004
#define FTS3_SEGMENT_PREFIX        0x00000008
#define FTS3_SEGMENT_SCAN          0x00000010

  if( !p ) return SQLITE_NOMEM;
  memset(p, 0, nByte);

  p->pFts3Tab = (Fts3Table *)&p[1];
  p->pFts3Tab->zDb = (char *)&p->pFts3Tab[1];
  p->pFts3Tab->zName = &p->pFts3Tab->zDb[nDb+1];
  p->pFts3Tab->db = db;
  p->pFts3Tab->nIndex = 1;

  memcpy((char *)p->pFts3Tab->zDb, zDb, nDb);
  memcpy((char *)p->pFts3Tab->zName, zFts3, nFts3);
  sqlite3Fts3Dequote((char *)p->pFts3Tab->zName);

  *ppVtab = (sqlite3_vtab *)p;
  return SQLITE_OK;

  if( idxNum&FTS4AUX_LE_CONSTRAINT ){
    int iIdx = (idxNum&FTS4AUX_GE_CONSTRAINT) ? 1 : 0;
    pCsr->zStop = sqlite3_mprintf("%s", sqlite3_value_text(apVal[iIdx]));
    pCsr->nStop = sqlite3_value_bytes(apVal[iIdx]);
    if( pCsr->zStop==0 ) return SQLITE_NOMEM;
  }

  rc = sqlite3Fts3SegReaderCursor(pFts3, FTS3_SEGCURSOR_ALL_TERM,
  rc = sqlite3Fts3SegReaderCursor(pFts3, 0, FTS3_SEGCURSOR_ALL,
      pCsr->filter.zTerm, pCsr->filter.nTerm, 0, isScan, &pCsr->csr
  );
  if( rc==SQLITE_OK ){
    rc = sqlite3Fts3SegReaderStart(pFts3, &pCsr->csr, &pCsr->filter);
  }

  if( rc==SQLITE_OK ) rc = fts3auxNextMethod(pCursor);

#include <assert.h>

typedef struct Fts3termTable Fts3termTable;
typedef struct Fts3termCursor Fts3termCursor;

struct Fts3termTable {
  sqlite3_vtab base;              /* Base class used by SQLite core */
  int bPrefix;                    /* True for an fts4prefix table */
  int iIndex;                     /* Index for Fts3Table.aIndex[] */
  Fts3Table *pFts3Tab;
};

struct Fts3termCursor {
  sqlite3_vtab_cursor base;       /* Base class used by SQLite core */
  Fts3SegReaderCursor csr;        /* Must be right after "base" */
  Fts3SegFilter filter;

  char const *zDb;                /* Name of database (e.g. "main") */
  char const *zFts3;              /* Name of fts3 table */
  int nDb;                        /* Result of strlen(zDb) */
  int nFts3;                      /* Result of strlen(zFts3) */
  int nByte;                      /* Bytes of space to allocate here */
  int rc;                         /* value returned by declare_vtab() */
  Fts3termTable *p;                /* Virtual table object to return */
  int iIndex = 0;

  if( argc==5 ){
    iIndex = atoi(argv[4]);
    argc--;
  }

  /* The user should specify a single argument - the name of an fts3 table. */
  if( argc!=4 ){
    *pzErr = sqlite3_mprintf(
        "wrong number of arguments to fts4term constructor"
    );
    return SQLITE_ERROR;

  if( !p ) return SQLITE_NOMEM;
  memset(p, 0, nByte);

  p->pFts3Tab = (Fts3Table *)&p[1];
  p->pFts3Tab->zDb = (char *)&p->pFts3Tab[1];
  p->pFts3Tab->zName = &p->pFts3Tab->zDb[nDb+1];
  p->pFts3Tab->db = db;
  p->pFts3Tab->nIndex = iIndex+1;
  p->bPrefix = (int)pCtx;
  p->iIndex = iIndex;

  memcpy((char *)p->pFts3Tab->zDb, zDb, nDb);
  memcpy((char *)p->pFts3Tab->zName, zFts3, nFts3);
  sqlite3Fts3Dequote((char *)p->pFts3Tab->zName);

  *ppVtab = (sqlite3_vtab *)p;
  return SQLITE_OK;

  testcase(pCsr->filter.zTerm);
  sqlite3Fts3SegReaderFinish(&pCsr->csr);
  memset(&pCsr->csr, 0, ((u8*)&pCsr[1]) - (u8*)&pCsr->csr);

  pCsr->filter.flags = FTS3_SEGMENT_REQUIRE_POS|FTS3_SEGMENT_IGNORE_EMPTY;
  pCsr->filter.flags |= FTS3_SEGMENT_SCAN;

  rc = sqlite3Fts3SegReaderCursor(pFts3, 
  rc = sqlite3Fts3SegReaderCursor(pFts3, p->iIndex, FTS3_SEGCURSOR_ALL,
      p->bPrefix ? FTS3_SEGCURSOR_ALL_PREFIX : FTS3_SEGCURSOR_ALL_TERM,
      pCsr->filter.zTerm, pCsr->filter.nTerm, 0, 1, &pCsr->csr
  );
  if( rc==SQLITE_OK ){
    rc = sqlite3Fts3SegReaderStart(pFts3, &pCsr->csr, &pCsr->filter);
  }
  if( rc==SQLITE_OK ){
    rc = fts3termNextMethod(pCursor);

     0,                           /* xRollback     */
     0,                           /* xFindFunction */
     0                            /* xRename       */
  };
  int rc;                         /* Return code */

  rc = sqlite3_create_module(db, "fts4term", &fts3term_module, 0);
  if( rc==SQLITE_OK ){
    rc = sqlite3_create_module(db, "fts4prefix", &fts3term_module, (void*)1);
  }
  return rc;
}

#endif
#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */

#define SQL_DELETE_ALL_STAT            6
#define SQL_SELECT_CONTENT_BY_ROWID    7
#define SQL_NEXT_SEGMENT_INDEX         8
#define SQL_INSERT_SEGMENTS            9
#define SQL_NEXT_SEGMENTS_ID          10
#define SQL_INSERT_SEGDIR             11
#define SQL_SELECT_LEVEL              12
#define SQL_SELECT_ALL_LEVEL          13
#define SQL_SELECT_LEVEL_RANGE        13
#define SQL_SELECT_LEVEL_COUNT        14
#define SQL_SELECT_SEGDIR_MAX_LEVEL   15
#define SQL_DELETE_SEGDIR_BY_LEVEL    16
#define SQL_DELETE_SEGDIR_LEVEL       16
#define SQL_DELETE_SEGMENTS_RANGE     17
#define SQL_CONTENT_INSERT            18
#define SQL_DELETE_DOCSIZE            19
#define SQL_REPLACE_DOCSIZE           20
#define SQL_SELECT_DOCSIZE            21
#define SQL_SELECT_DOCTOTAL           22
#define SQL_REPLACE_DOCTOTAL          23

#define SQL_SELECT_ALL_PREFIX_LEVEL   24
#define SQL_DELETE_ALL_TERMS_SEGDIR   25

#define SQL_DELETE_ALL_TERMS_SEGDIR   25
#define SQL_DELETE_SEGDIR_RANGE       26
#define SQL_DELETE_ALL_PREFIX_SEGDIR  26

/*
** This function is used to obtain an SQLite prepared statement handle
** for the statement identified by the second argument. If successful,
** *pp is set to the requested statement handle and SQLITE_OK returned.
** Otherwise, an SQLite error code is returned and *pp is set to 0.
**

/* 10 */  "SELECT coalesce((SELECT max(blockid) FROM %Q.'%q_segments') + 1, 1)",
/* 11 */  "INSERT INTO %Q.'%q_segdir' VALUES(?,?,?,?,?,?)",

          /* Return segments in order from oldest to newest.*/ 
/* 12 */  "SELECT idx, start_block, leaves_end_block, end_block, root "
            "FROM %Q.'%q_segdir' WHERE level = ? ORDER BY idx ASC",
/* 13 */  "SELECT idx, start_block, leaves_end_block, end_block, root "
            "FROM %Q.'%q_segdir' WHERE level < " FTS3_SEGDIR_PREFIXLEVEL_STR
            " ORDER BY level DESC, idx ASC",
            "FROM %Q.'%q_segdir' WHERE level BETWEEN ? AND ?"
            "ORDER BY level DESC, idx ASC",

/* 14 */  "SELECT count(*) FROM %Q.'%q_segdir' WHERE level = ?",
/* 15 */  "SELECT max(level) FROM %Q.'%q_segdir' WHERE level < (?+1)*"
/* 15 */  "SELECT max(level) FROM %Q.'%q_segdir' WHERE level BETWEEN ? AND ?",
            FTS3_SEGDIR_PREFIXLEVEL_STR,

/* 16 */  "DELETE FROM %Q.'%q_segdir' WHERE level = ?",
/* 17 */  "DELETE FROM %Q.'%q_segments' WHERE blockid BETWEEN ? AND ?",
/* 18 */  "INSERT INTO %Q.'%q_content' VALUES(%s)",
/* 19 */  "DELETE FROM %Q.'%q_docsize' WHERE docid = ?",
/* 20 */  "REPLACE INTO %Q.'%q_docsize' VALUES(?,?)",
/* 21 */  "SELECT size FROM %Q.'%q_docsize' WHERE docid=?",
/* 22 */  "SELECT value FROM %Q.'%q_stat' WHERE id=0",
/* 23 */  "REPLACE INTO %Q.'%q_stat' VALUES(0,?)",
/* 24 */  "SELECT idx, start_block, leaves_end_block, end_block, root "
            "FROM %Q.'%q_segdir' WHERE level >= " FTS3_SEGDIR_PREFIXLEVEL_STR
            " ORDER BY level DESC, idx ASC",
/* 24 */  "",
/* 25 */  "",

/* 25 */ "DELETE FROM %Q.'%q_segdir' WHERE level<" FTS3_SEGDIR_PREFIXLEVEL_STR,
/* 26 */ "DELETE FROM %Q.'%q_segdir' WHERE level>=" FTS3_SEGDIR_PREFIXLEVEL_STR,
/* 26 */ "DELETE FROM %Q.'%q_segdir' WHERE level BETWEEN ? AND ?",

  };
  int rc = SQLITE_OK;
  sqlite3_stmt *pStmt;

  assert( SizeofArray(azSql)==SizeofArray(p->aStmt) );
  assert( eStmt<SizeofArray(azSql) && eStmt>=0 );
  

**
**   0: idx
**   1: start_block
**   2: leaves_end_block
**   3: end_block
**   4: root
*/
int sqlite3Fts3AllSegdirs(Fts3Table *p, int iLevel, sqlite3_stmt **ppStmt){
int sqlite3Fts3AllSegdirs(
  Fts3Table *p,                   /* FTS3 table */
  int iIndex,                     /* Index for p->aIndex[] */
  int iLevel,                     /* Level to select */
  sqlite3_stmt **ppStmt           /* OUT: Compiled statement */
){
  int rc;
  sqlite3_stmt *pStmt = 0;

  if( iLevel==FTS3_SEGCURSOR_ALL_PREFIX ){
    rc = fts3SqlStmt(p, SQL_SELECT_ALL_PREFIX_LEVEL, &pStmt, 0);
  }else if( iLevel==FTS3_SEGCURSOR_ALL_TERM ){
    rc = fts3SqlStmt(p, SQL_SELECT_ALL_LEVEL, &pStmt, 0);
  assert( iLevel==FTS3_SEGCURSOR_ALL || iLevel>=0 );
  assert( iLevel<FTS3_SEGDIR_MAXLEVEL );
  assert( iIndex>=0 && iIndex<p->nIndex );

  if( iLevel==FTS3_SEGCURSOR_ALL ){
    /* "SELECT * FROM %_segdir WHERE level BETWEEN ? AND ? ORDER BY ..." */
    rc = fts3SqlStmt(p, SQL_SELECT_LEVEL_RANGE, &pStmt, 0);
    if( rc==SQLITE_OK ){ 
      sqlite3_bind_int(pStmt, 1, iIndex*FTS3_SEGDIR_MAXLEVEL);
      sqlite3_bind_int(pStmt, 2, (iIndex+1)*FTS3_SEGDIR_MAXLEVEL-1);
    }
  }else{
    assert( iLevel>=0 );
    /* "SELECT * FROM %_segdir WHERE level = ? ORDER BY ..." */
    rc = fts3SqlStmt(p, SQL_SELECT_LEVEL, &pStmt, 0);
    if( rc==SQLITE_OK ) sqlite3_bind_int(pStmt, 1, iLevel);
    if( rc==SQLITE_OK ){ 
      sqlite3_bind_int(pStmt, 1, iLevel+iIndex*FTS3_SEGDIR_MAXLEVEL);
    }
  }
  *ppStmt = pStmt;
  return rc;
}


/*

    }
  }
  if( rc==SQLITE_OK ){
    p->nPendingData += (pList->nData + nToken + sizeof(Fts3HashElem));
  }
  return rc;
}

 


/*
** Tokenize the nul-terminated string zText and add all tokens to the
** pending-terms hash-table. The docid used is that currently stored in
** p->iPrevDocid, and the column is specified by argument iCol.
**
** If successful, SQLITE_OK is returned. Otherwise, an SQLite error code.

  }
  pCsr->pTokenizer = pTokenizer;

  xNext = pModule->xNext;
  while( SQLITE_OK==rc
      && SQLITE_OK==(rc = xNext(pCsr, &zToken, &nToken, &iStart, &iEnd, &iPos))
  ){
    int i;
    if( iPos>=nWord ) nWord = iPos+1;

    /* Positions cannot be negative; we use -1 as a terminator internally.
    ** Tokens must have a non-zero length.
    */
    if( iPos<0 || !zToken || nToken<=0 ){
      rc = SQLITE_ERROR;
      break;
    }

    /* Add the term to the terms index */
    rc = fts3PendingTermsAddOne(p,iCol,iPos,&p->pendingTerms,zToken,nToken);
    if( p->bPrefix ){
      int n = (nToken > FTS3_MAX_PREFIX ? FTS3_MAX_PREFIX : nToken);
      for(; n>0 && rc==SQLITE_OK; n--){
        rc = fts3PendingTermsAddOne(p,iCol,iPos,&p->pendingPrefixes,zToken,n);
    rc = fts3PendingTermsAddOne(
        p, iCol, iPos, &p->aIndex[0].hPending, zToken, nToken
    );
    
    /* Add the term to each of the prefix indexes that it is not too 
    ** short for. */
    for(i=1; rc==SQLITE_OK && i<p->nIndex; i++){
      struct Fts3Index *pIndex = &p->aIndex[i];
      if( nToken<pIndex->nPrefix ) continue;
      rc = fts3PendingTermsAddOne(
      }
          p, iCol, iPos, &pIndex->hPending, zToken, pIndex->nPrefix
      );
    }
  }

  pModule->xClose(pCsr);
  *pnWord = nWord;
  return (rc==SQLITE_DONE ? SQLITE_OK : rc);
}

    if( rc!=SQLITE_OK ) return rc;
  }
  p->iPrevDocid = iDocid;
  return SQLITE_OK;
}

/*
** Discard the contents of the pending-terms hash table. 
** Discard the contents of the pending-terms hash tables. 
*/
void sqlite3Fts3PendingTermsClear(Fts3Table *p){
  int i;
  for(i=0; i<p->nIndex; i++){
  Fts3HashElem *pElem;
  for(pElem=fts3HashFirst(&p->pendingTerms); pElem; pElem=fts3HashNext(pElem)){
    sqlite3_free(fts3HashData(pElem));
  }
  fts3HashClear(&p->pendingTerms);
    Fts3HashElem *pElem;
    Fts3Hash *pHash = &p->aIndex[i].hPending;
    for(pElem=fts3HashFirst(pHash); pElem; pElem=fts3HashNext(pElem)){
      sqlite3_free(fts3HashData(pElem));
    }
    fts3HashClear(pHash);
  p->nPendingData = 0;
}

  }
  p->nPendingData = 0;
/*
** Discard the contents of the pending-prefixes hash table. 
*/
void sqlite3Fts3PendingPrefixesClear(Fts3Table *p){
  Fts3HashElem *pElem;
  for(pElem=fts3HashFirst(&p->pendingPrefixes); pElem; pElem=fts3HashNext(pElem)){
    sqlite3_free(fts3HashData(pElem));
  }
  fts3HashClear(&p->pendingPrefixes);
}

/*
** This function is called by the xUpdate() method as part of an INSERT
** operation. It adds entries for each term in the new record to the
** pendingTerms hash table.
**

** pending terms.
*/
static int fts3DeleteAll(Fts3Table *p){
  int rc = SQLITE_OK;             /* Return code */

  /* Discard the contents of the pending-terms hash table. */
  sqlite3Fts3PendingTermsClear(p);
  sqlite3Fts3PendingPrefixesClear(p);

  /* Delete everything from the %_content, %_segments and %_segdir tables. */
  fts3SqlExec(&rc, p, SQL_DELETE_ALL_CONTENT, 0);
  fts3SqlExec(&rc, p, SQL_DELETE_ALL_SEGMENTS, 0);
  fts3SqlExec(&rc, p, SQL_DELETE_ALL_SEGDIR, 0);
  if( p->bHasDocsize ){
    fts3SqlExec(&rc, p, SQL_DELETE_ALL_DOCSIZE, 0);

  *pRC = rc;
}

/*
** Forward declaration to account for the circular dependency between
** functions fts3SegmentMerge() and fts3AllocateSegdirIdx().
*/
static int fts3SegmentMerge(Fts3Table *, int);
static int fts3SegmentMerge(Fts3Table *, int, int);

/* 
** This function allocates a new level iLevel index in the segdir table.
** Usually, indexes are allocated within a level sequentially starting
** with 0, so the allocated index is one greater than the value returned
** by:
**
**   SELECT max(idx) FROM %_segdir WHERE level = :iLevel
**
** However, if there are already FTS3_MERGE_COUNT indexes at the requested
** level, they are merged into a single level (iLevel+1) segment and the 
** allocated index is 0.
**
** If successful, *piIdx is set to the allocated index slot and SQLITE_OK
** returned. Otherwise, an SQLite error code is returned.
*/
static int fts3AllocateSegdirIdx(Fts3Table *p, int iLevel, int *piIdx){
static int fts3AllocateSegdirIdx(
  Fts3Table *p, 
  int iIndex,                     /* Index for p->aIndex */
  int iLevel, 
  int *piIdx
){
  int rc;                         /* Return Code */
  sqlite3_stmt *pNextIdx;         /* Query for next idx at level iLevel */
  int iNext = 0;                  /* Result of query pNextIdx */

  /* Set variable iNext to the next available segdir index at level iLevel. */
  rc = fts3SqlStmt(p, SQL_NEXT_SEGMENT_INDEX, &pNextIdx, 0);
  if( rc==SQLITE_OK ){
    sqlite3_bind_int(pNextIdx, 1, iLevel);
    sqlite3_bind_int(pNextIdx, 1, iIndex*FTS3_SEGDIR_MAXLEVEL + iLevel);
    if( SQLITE_ROW==sqlite3_step(pNextIdx) ){
      iNext = sqlite3_column_int(pNextIdx, 0);
    }
    rc = sqlite3_reset(pNextIdx);
  }

  if( rc==SQLITE_OK ){
    /* If iNext is FTS3_MERGE_COUNT, indicating that level iLevel is already
    ** full, merge all segments in level iLevel into a single iLevel+1
    ** segment and allocate (newly freed) index 0 at level iLevel. Otherwise,
    ** if iNext is less than FTS3_MERGE_COUNT, allocate index iNext.
    */
    if( iNext>=FTS3_MERGE_COUNT ){
      rc = fts3SegmentMerge(p, iLevel);
      rc = fts3SegmentMerge(p, iIndex, iLevel);
      *piIdx = 0;
    }else{
      *piIdx = iNext;
    }
  }

  return rc;

**
** Whereas if isPrefixIter is zero, the terms visited are:
**
**   firebird mysql sqlite
*/
int sqlite3Fts3SegReaderPending(
  Fts3Table *p,                   /* Virtual table handle */
  int iIndex,                     /* Index for p->aIndex */
  const char *zTerm,              /* Term to search for */
  int nTerm,                      /* Size of buffer zTerm */
  int isMultiTerm,                /* True to visit multiple terms */
  int bPrefix,                    /* True for a prefix iterator */
  int isPrefixIter,               /* 0->pendingTerms, 1->pendingPrefixes */
  Fts3SegReader **ppReader        /* OUT: SegReader for pending-terms */
){
  Fts3SegReader *pReader = 0;     /* Fts3SegReader object to return */
  Fts3HashElem **aElem = 0;       /* Array of term hash entries to scan */
  int nElem = 0;                  /* Size of array at aElem */
  int rc = SQLITE_OK;             /* Return Code */
  Fts3Hash *pHash;

  pHash = &p->aIndex[iIndex].hPending;
  if( isMultiTerm ){
  if( bPrefix ){
    int nAlloc = 0;               /* Size of allocated array at aElem */
    Fts3HashElem *pE = 0;         /* Iterator variable */
    Fts3Hash *pHash;

    pHash = (isPrefixIter ? &p->pendingPrefixes : &p->pendingTerms);

    for(pE=fts3HashFirst(pHash); pE; pE=fts3HashNext(pE)){
      char *zKey = (char *)fts3HashKey(pE);
      int nKey = fts3HashKeysize(pE);
      if( nTerm==0 || (nKey>=nTerm && 0==memcmp(zKey, zTerm, nTerm)) ){
        if( nElem==nAlloc ){
          Fts3HashElem **aElem2;

    if( nElem>1 ){
      qsort(aElem, nElem, sizeof(Fts3HashElem *), fts3CompareElemByTerm);
    }

  }else{
    /* The query is a simple term lookup that matches at most one term in
    ** the index. All that is required is a straight hash-lookup. */
    Fts3HashElem *pE = fts3HashFindElem(&p->pendingTerms, zTerm, nTerm);
    Fts3HashElem *pE = fts3HashFindElem(pHash, zTerm, nTerm);
    if( pE ){
      aElem = &pE;
      nElem = 1;
    }
  }

  if( nElem>0 ){
    int nByte = sizeof(Fts3SegReader) + (nElem+1)*sizeof(Fts3HashElem *);
    pReader = (Fts3SegReader *)sqlite3_malloc(nByte);
    if( !pReader ){
      rc = SQLITE_NOMEM;
    }else{
      memset(pReader, 0, nByte);
      pReader->iIdx = 0x7FFFFFFF;
      pReader->ppNextElem = (Fts3HashElem **)&pReader[1];
      memcpy(pReader->ppNextElem, aElem, nElem*sizeof(Fts3HashElem *));
    }
  }

  if( isMultiTerm ){
  if( bPrefix ){
    sqlite3_free(aElem);
  }
  *ppReader = pReader;
  return rc;
}

/*

    }
    rc = sqlite3_reset(pStmt);
  }
  return rc;
}

/*
** Set *pnMax to the largest segment level in the database for either the
** Set *pnMax to the largest segment level in the database for the index
** terms index (if parameter bPrefixIndex is 0) or the prefixes index (if
** parameter bPrefixIndex is 1).
** iIndex.
**
** Segment levels are stored in the 'level' column of the %_segdir table.
**
** Return SQLITE_OK if successful, or an SQLite error code if not.
*/
static int fts3SegmentMaxLevel(Fts3Table *p, int bPrefixIndex, int *pnMax){
static int fts3SegmentMaxLevel(Fts3Table *p, int iIndex, int *pnMax){
  sqlite3_stmt *pStmt;
  int rc;
  assert( bPrefixIndex==0 || bPrefixIndex==1 );
  assert( iIndex>=0 && iIndex<p->nIndex );

  /* Set pStmt to the compiled version of:
  **
  **   SELECT max(level) FROM %Q.'%q_segdir' WHERE level < (?+1) * 1024 
  **   SELECT max(level) FROM %Q.'%q_segdir' WHERE level BETWEEN ? AND ?
  **
  ** (1024 is actually the value of macro FTS3_SEGDIR_PREFIXLEVEL_STR).
  */
  rc = fts3SqlStmt(p, SQL_SELECT_SEGDIR_MAX_LEVEL, &pStmt, 0);
  if( rc!=SQLITE_OK ) return rc;
  sqlite3_bind_int(pStmt, 1, bPrefixIndex);
  sqlite3_bind_int(pStmt, 1, iIndex*FTS3_SEGDIR_MAXLEVEL);
  sqlite3_bind_int(pStmt, 2, (iIndex+1)*FTS3_SEGDIR_MAXLEVEL - 1);
  if( SQLITE_ROW==sqlite3_step(pStmt) ){
    *pnMax = sqlite3_column_int(pStmt, 0);
  }
  return sqlite3_reset(pStmt);
}

/*

**   2) deletes all %_segdir entries with level iLevel, or all %_segdir
**      entries regardless of level if (iLevel<0).
**
** SQLITE_OK is returned if successful, otherwise an SQLite error code.
*/
static int fts3DeleteSegdir(
  Fts3Table *p,                   /* Virtual table handle */
  int iIndex,                     /* Index for p->aIndex */
  int iLevel,                     /* Level of %_segdir entries to delete */
  Fts3SegReader **apSegment,      /* Array of SegReader objects */
  int nReader                     /* Size of array apSegment */
){
  int rc;                         /* Return Code */
  int i;                          /* Iterator variable */
  sqlite3_stmt *pDelete;          /* SQL statement to delete rows */

      rc = sqlite3_reset(pDelete);
    }
  }
  if( rc!=SQLITE_OK ){
    return rc;
  }

  assert( iLevel>=0 
  assert( iLevel>=0 || iLevel==FTS3_SEGCURSOR_ALL );
       || iLevel==FTS3_SEGCURSOR_ALL_TERM
       || iLevel==FTS3_SEGCURSOR_ALL_PREFIX 
       || iLevel==FTS3_SEGCURSOR_PENDING
       || iLevel==FTS3_SEGCURSOR_PENDING_PREFIX 
  );
  if( iLevel==FTS3_SEGCURSOR_ALL_TERM ){
    fts3SqlExec(&rc, p, SQL_DELETE_ALL_TERMS_SEGDIR, 0);
  }else if( iLevel==FTS3_SEGCURSOR_ALL_PREFIX ){
  if( iLevel==FTS3_SEGCURSOR_ALL ){
    rc = fts3SqlStmt(p, SQL_DELETE_SEGDIR_RANGE, &pDelete, 0);
    if( rc==SQLITE_OK ){
    fts3SqlExec(&rc, p, SQL_DELETE_ALL_PREFIX_SEGDIR, 0);
  }else if( iLevel==FTS3_SEGCURSOR_PENDING_PREFIX ){
    sqlite3Fts3PendingPrefixesClear(p);
  }else if( iLevel==FTS3_SEGCURSOR_PENDING ){
    sqlite3Fts3PendingTermsClear(p);
  }else if( iLevel>=0 ){
    rc = fts3SqlStmt(p, SQL_DELETE_SEGDIR_BY_LEVEL, &pDelete, 0);
      sqlite3_bind_int(pDelete, 1, iIndex*FTS3_SEGDIR_MAXLEVEL);
      sqlite3_bind_int(pDelete, 2, (iIndex+1) * FTS3_SEGDIR_MAXLEVEL - 1);
    }
  }else{
    rc = fts3SqlStmt(p, SQL_DELETE_SEGDIR_LEVEL, &pDelete, 0);
    if( rc==SQLITE_OK ){
      sqlite3_bind_int(pDelete, 1, iLevel);
      sqlite3_step(pDelete);
      rc = sqlite3_reset(pDelete);
    }
      sqlite3_bind_int(pDelete, 1, iIndex*FTS3_SEGDIR_MAXLEVEL + iLevel);
    }
  }

  if( rc==SQLITE_OK ){
    sqlite3_step(pDelete);
    rc = sqlite3_reset(pDelete);
  }
  }

  return rc;
}

/*
** When this function is called, buffer *ppList (size *pnList bytes) contains 
** a position list that may (or may not) feature multiple columns. This

** currently present in the database.
**
** If this function is called with iLevel<0, but there is only one
** segment in the database, SQLITE_DONE is returned immediately. 
** Otherwise, if successful, SQLITE_OK is returned. If an error occurs, 
** an SQLite error code is returned.
*/
static int fts3SegmentMerge(Fts3Table *p, int iLevel){
static int fts3SegmentMerge(Fts3Table *p, int iIndex, int iLevel){
  int rc;                         /* Return code */
  int iIdx = 0;                   /* Index of new segment */
  int iNewLevel = 0;              /* Level to create new segment at */
  int iNewLevel = 0;              /* Level/index to create new segment at */
  SegmentWriter *pWriter = 0;     /* Used to write the new, merged, segment */
  Fts3SegFilter filter;           /* Segment term filter condition */
  Fts3SegReaderCursor csr;        /* Cursor to iterate through level(s) */
  int bIgnoreEmpty = 0;           /* True to ignore empty segments */

  assert( iLevel==FTS3_SEGCURSOR_ALL
       || iLevel==FTS3_SEGCURSOR_PENDING
       || iLevel>=0
  );
  assert( iLevel<FTS3_SEGDIR_MAXLEVEL );
  assert( iIndex>=0 && iIndex<p->nIndex );

  rc = sqlite3Fts3SegReaderCursor(p, iLevel, 0, 0, 1, 0, &csr);
  rc = sqlite3Fts3SegReaderCursor(p, iIndex, iLevel, 0, 0, 1, 0, &csr);
  if( rc!=SQLITE_OK || csr.nSegment==0 ) goto finished;

  if( iLevel==FTS3_SEGCURSOR_ALL_TERM || iLevel==FTS3_SEGCURSOR_ALL_PREFIX ){
  if( iLevel==FTS3_SEGCURSOR_ALL ){
    /* This call is to merge all segments in the database to a single
    ** segment. The level of the new segment is equal to the the numerically 
    ** greatest segment level currently present in the database. The index
    ** of the new segment is always 0.  */
    ** greatest segment level currently present in the database for this
    ** index. The idx of the new segment is always 0.  */
    if( csr.nSegment==1 ){
      rc = SQLITE_DONE;
      goto finished;
    }
    rc = fts3SegmentMaxLevel(p, iLevel==FTS3_SEGCURSOR_ALL_PREFIX, &iNewLevel);
    rc = fts3SegmentMaxLevel(p, iIndex, &iNewLevel);
    bIgnoreEmpty = 1;

  }else if( iLevel==FTS3_SEGCURSOR_PENDING ){
    iNewLevel = iIndex * FTS3_SEGDIR_MAXLEVEL; 
    rc = fts3AllocateSegdirIdx(p, iIndex, 0, &iIdx);
  }else{
    /* This call is to merge all segments at level iLevel. find the next
    ** available segment index at level iLevel+1. The call to
    ** fts3AllocateSegdirIdx() will merge the segments at level iLevel+1 to 
    ** a single iLevel+2 segment if necessary.  */
    if( iLevel==FTS3_SEGCURSOR_PENDING ){
      iNewLevel = 0;
    }else if( iLevel==FTS3_SEGCURSOR_PENDING_PREFIX ){
      iNewLevel = FTS3_SEGDIR_PREFIXLEVEL;
    }else{
      iNewLevel = iLevel+1;
    }
    rc = fts3AllocateSegdirIdx(p, iNewLevel, &iIdx);
    rc = fts3AllocateSegdirIdx(p, iIndex, iLevel+1, &iIdx);
    iNewLevel = iIndex * FTS3_SEGDIR_MAXLEVEL + iLevel+1;
  }
  if( rc!=SQLITE_OK ) goto finished;
  assert( csr.nSegment>0 );
  assert( iNewLevel>=0 );
  assert( iNewLevel>=(iIndex*FTS3_SEGDIR_MAXLEVEL) );
  assert( iNewLevel<((iIndex+1)*FTS3_SEGDIR_MAXLEVEL) );

  memset(&filter, 0, sizeof(Fts3SegFilter));
  filter.flags = FTS3_SEGMENT_REQUIRE_POS;
  filter.flags |= (bIgnoreEmpty ? FTS3_SEGMENT_IGNORE_EMPTY : 0);

  rc = sqlite3Fts3SegReaderStart(p, &csr, &filter);
  while( SQLITE_OK==rc ){
    rc = sqlite3Fts3SegReaderStep(p, &csr);
    if( rc!=SQLITE_ROW ) break;
    rc = fts3SegWriterAdd(p, &pWriter, 1, 
        csr.zTerm, csr.nTerm, csr.aDoclist, csr.nDoclist);
  }
  if( rc!=SQLITE_OK ) goto finished;
  assert( pWriter );

  if( iLevel!=FTS3_SEGCURSOR_PENDING ){
  rc = fts3DeleteSegdir(p, iLevel, csr.apSegment, csr.nSegment);
  if( rc!=SQLITE_OK ) goto finished;
    rc = fts3DeleteSegdir(p, iIndex, iLevel, csr.apSegment, csr.nSegment);
    if( rc!=SQLITE_OK ) goto finished;
  }
  rc = fts3SegWriterFlush(p, pWriter, iNewLevel, iIdx);

 finished:
  fts3SegWriterFree(pWriter);
  sqlite3Fts3SegReaderFinish(&csr);
  return rc;
}


/* 
** Flush the contents of pendingTerms to a level 0 segment.
** Flush the contents of pendingTerms to level 0 segments.
*/
int sqlite3Fts3PendingTermsFlush(Fts3Table *p){
  int rc = SQLITE_OK;
  if( p->bPrefix ){
  int i;
    rc = fts3SegmentMerge(p, FTS3_SEGCURSOR_PENDING_PREFIX);
  }
  if( rc==SQLITE_OK || rc==SQLITE_DONE ){
    rc = fts3SegmentMerge(p, FTS3_SEGCURSOR_PENDING);
  for(i=0; rc==SQLITE_OK && i<p->nIndex; i++){
    rc = fts3SegmentMerge(p, i, FTS3_SEGCURSOR_PENDING);
  }
  if( rc==SQLITE_DONE ){
    if( rc==SQLITE_DONE ) rc = SQLITE_OK;
    rc = SQLITE_OK;
  }
  sqlite3Fts3PendingTermsClear(p);
  return rc;
}

/*
** Encode N integers as varints into a blob.
*/
static void fts3EncodeIntArray(

    return;
  }
  sqlite3_bind_blob(pStmt, 1, pBlob, nBlob, SQLITE_STATIC);
  sqlite3_step(pStmt);
  *pRC = sqlite3_reset(pStmt);
  sqlite3_free(a);
}

static int fts3DoOptimize(Fts3Table *p, int bReturnDone){
  int i;
  int bSeenDone = 0;
  int rc = SQLITE_OK;
  for(i=0; rc==SQLITE_OK && i<p->nIndex; i++){
    rc = fts3SegmentMerge(p, i, FTS3_SEGCURSOR_ALL);
    if( rc==SQLITE_DONE ){
      bSeenDone = 1;
      rc = SQLITE_OK;
    }
  }
  sqlite3Fts3SegmentsClose(p);
  sqlite3Fts3PendingTermsClear(p);

  return (rc==SQLITE_OK && bReturnDone && bSeenDone) ? SQLITE_DONE : rc;
}

/*
** Handle a 'special' INSERT of the form:
**
**   "INSERT INTO tbl(tbl) VALUES(<expr>)"
**
** Argument pVal contains the result of <expr>. Currently the only 
** meaningful value to insert is the text 'optimize'.
*/
static int fts3SpecialInsert(Fts3Table *p, sqlite3_value *pVal){
  int rc;                         /* Return Code */
  const char *zVal = (const char *)sqlite3_value_text(pVal);
  int nVal = sqlite3_value_bytes(pVal);

  if( !zVal ){
    return SQLITE_NOMEM;
  }else if( nVal==8 && 0==sqlite3_strnicmp(zVal, "optimize", 8) ){
    rc = fts3SegmentMerge(p, FTS3_SEGCURSOR_ALL_PREFIX);
    if( rc==SQLITE_OK ){
      rc = fts3SegmentMerge(p, FTS3_SEGCURSOR_ALL_TERM);
    rc = fts3DoOptimize(p, 0);
    }
#ifdef SQLITE_TEST
  }else if( nVal>9 && 0==sqlite3_strnicmp(zVal, "nodesize=", 9) ){
    p->nNodeSize = atoi(&zVal[9]);
    rc = SQLITE_OK;
  }else if( nVal>11 && 0==sqlite3_strnicmp(zVal, "maxpending=", 9) ){
    p->nMaxPendingData = atoi(&zVal[11]);
    rc = SQLITE_OK;
#endif
  }else{
    rc = SQLITE_ERROR;
  }

  sqlite3Fts3SegmentsClose(p);
  sqlite3Fts3PendingTermsClear(p);
  sqlite3Fts3PendingPrefixesClear(p);
  return rc;
}

/*
** Return the deferred doclist associated with deferred token pDeferred.
** This function assumes that sqlite3Fts3CacheDeferredDoclists() has already
** been called to allocate and populate the doclist.

/* 
** Flush any data in the pending-terms hash table to disk. If successful,
** merge all segments in the database (including the new segment, if 
** there was any data to flush) into a single segment. 
*/
int sqlite3Fts3Optimize(Fts3Table *p){
  int rc;
  int bReturnDone = 0;
  rc = sqlite3_exec(p->db, "SAVEPOINT fts3", 0, 0, 0);
  if( rc==SQLITE_OK ){
    rc = fts3SegmentMerge(p, FTS3_SEGCURSOR_ALL_PREFIX);
    if( rc==SQLITE_OK ){
      rc = fts3SegmentMerge(p, FTS3_SEGCURSOR_ALL_TERM);
    }
    if( rc==SQLITE_DONE ){
      bReturnDone = 1;
      rc = SQLITE_OK;
    rc = fts3DoOptimize(p, 1);
    }
    if( rc==SQLITE_OK ){
      rc = sqlite3_exec(p->db, "RELEASE fts3", 0, 0, 0);
      if( rc==SQLITE_OK ){
    if( rc==SQLITE_OK || rc==SQLITE_DONE ){
      int rc2 = sqlite3_exec(p->db, "RELEASE fts3", 0, 0, 0);
      if( rc2!=SQLITE_OK ) rc = rc2;
        sqlite3Fts3PendingTermsClear(p);
        sqlite3Fts3PendingPrefixesClear(p);
      }
    }else{
      sqlite3_exec(p->db, "ROLLBACK TO fts3", 0, 0, 0);
      sqlite3_exec(p->db, "RELEASE fts3", 0, 0, 0);
    }
  }
  sqlite3Fts3SegmentsClose(p);
  return ((rc==SQLITE_OK && bReturnDone) ? SQLITE_DONE : rc);
  return rc;
}

#endif

# This file implements regression tests for SQLite library.  The
# focus of this script is testing the FTS3 module.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix fts3prefix

ifcapable !fts3 {
  finish_test
  return
}

# This proc tests that the prefixes index appears to represent the same content
# as the terms index.
#
proc fts3_terms_and_prefixes {db tbl} {
  $db eval "CREATE VIRTUAL TABLE fts3check1 USING fts4term($tbl);"
  $db eval "CREATE VIRTUAL TABLE fts3check2 USING fts4prefix($tbl);"
proc fts3_terms_and_prefixes {db tbl prefixlengths} {

  set iIndex 0
  foreach len $prefixlengths {
    incr iIndex
    $db eval {
      DROP TABLE IF EXISTS fts3check1;
      DROP TABLE IF EXISTS fts3check2;
    }
    $db eval "CREATE VIRTUAL TABLE fts3check1 USING fts4term($tbl, 0);"
    $db eval "CREATE VIRTUAL TABLE fts3check2 USING fts4term($tbl, $iIndex);"

  $db eval {
    CREATE TEMP TABLE terms AS SELECT * FROM fts3check1;
    CREATE TEMP TABLE prefixes AS SELECT * FROM fts3check2;
    CREATE INDEX temp.idx ON prefixes(term);
    DROP TABLE fts3check1;
    DROP TABLE fts3check2;
  }
    $db eval {
      DROP TABLE IF EXISTS temp.terms;
      DROP TABLE IF EXISTS temp.prefixes;
      CREATE TEMP TABLE terms AS SELECT * FROM fts3check1;
      CREATE TEMP TABLE prefixes AS SELECT * FROM fts3check2;
      CREATE INDEX temp.idx ON prefixes(term);
      DROP TABLE fts3check1;
      DROP TABLE fts3check2;
    }

    set nExpect 0
  $db eval { SELECT term, docid, col, pos FROM temp.terms } a {
    set nMax [expr [string length $a(term)] - 1]
    $db eval { SELECT term, docid, col, pos FROM temp.terms } a {
      if {[string length $a(term)]<$len} continue
    if {$nMax>8} {set nMax 8}
    for {set n 0} {$n < $nMax} {incr n} {
      set t [string range $a(term) 0 $n]
      incr nExpect
      set prefix [string range $a(term) 0 [expr $len-1]]
      set r [$db one { 
        SELECT count(*) FROM temp.prefixes WHERE 
        term = $t AND docid = $a(docid) AND col = $a(col) AND pos = $a(pos)
        term = $prefix AND docid = $a(docid) AND col = $a(col) AND pos = $a(pos)
      }]
      if {$r != 1} {
        error "$t, $a(docid), $a(col), $a(pos)"
      }
    }
  }

  execsql { DROP TABLE temp.prefixes }
  execsql { DROP TABLE temp.terms }

    set nCount [$db one {SELECT count(*) FROM temp.prefixes}]
    if {$nCount != $nExpect} {
      error "prefixes.count(*) is $nCount expected $nExpect"
    }
  
    execsql { DROP TABLE temp.prefixes }
    execsql { DROP TABLE temp.terms }

  set terms_layout [$db eval " 
    set list [list]
    SELECT level, idx FROM ${tbl}_segdir WHERE level < 1024 ORDER by 1, 2
  "]
  set prefixes_layout [$db eval " 
    SELECT level-1024, idx FROM ${tbl}_segdir WHERE level >= 1024 ORDER by 1, 2
  "]

  if {$terms_layout != $prefixes_layout} {
    $db eval "
      SELECT sum( 1 << (16*(level%1024)) ) AS total, (level/1024) AS tree 
      FROM ${tbl}_segdir GROUP BY tree
    " {
      lappend list [list $total $tree]
    }

    puts "TERMS LAYOUT:  $terms_layout"
    puts "PREFIX LAYOUT: $prefixes_layout"
    error "Terms and prefixes are comprised of different b-trees"
  }

    if { [lsort -integer -index 0 $list] != [lsort -integer -index 1 $list] } {
      error "inconsistent tree structures: $list"
    }
  }

  return ""
}
proc fts3_tap_test {tn db tbl} {
  uplevel [list do_test $tn [list fts3_terms_and_prefixes $db $tbl] ""]
proc fts3_tap_test {tn db tbl lens} {
  uplevel [list do_test $tn [list fts3_terms_and_prefixes $db $tbl $lens] ""]
}

#-------------------------------------------------------------------------
# Test cases 1.* are a sanity check. They test that the prefixes index is
# being constructed correctly for the simplest possible case.
#
do_execsql_test 1.1 {
  CREATE VIRTUAL TABLE t1 USING fts4(prefix=1);
  CREATE VIRTUAL TABLE prefixes USING fts4prefix(t1);
  CREATE VIRTUAL TABLE t1 USING fts4(prefix='1,3,6');

  CREATE VIRTUAL TABLE p1 USING fts4term(t1, 1);
  CREATE VIRTUAL TABLE p2 USING fts4term(t1, 2);
  CREATE VIRTUAL TABLE p3 USING fts4term(t1, 3);
  CREATE VIRTUAL TABLE terms USING fts4term(t1);
}
do_execsql_test 1.2 {
  INSERT INTO t1 VALUES('sqlite mysql firebird');
}
do_execsql_test 1.3 {
  SELECT term FROM prefixes;
} {f fi fir fire fireb firebi firebir firebird m my mys mysq mysql s sq sql sqli sqlit sqlite}
do_execsql_test 1.3.1 { SELECT term FROM p1 } {f m s}
do_execsql_test 1.3.2 { SELECT term FROM p2 } {fir mys sql}
do_execsql_test 1.3.3 { SELECT term FROM p3 } {firebi sqlite}
do_execsql_test 1.4 {
  SELECT term FROM terms;
} {firebird mysql sqlite}

fts3_tap_test 1.5 db t1
fts3_tap_test 1.5 db t1 {1 3 6}

#-------------------------------------------------------------------------
# A slightly more complicated dataset. This test also verifies that DELETE
# operations do not corrupt the prefixes index.
#
do_execsql_test 2.1 {
  INSERT INTO t1 VALUES('FTS3 and FTS4 are an SQLite virtual table modules');

  INSERT INTO t1 VALUES('modules for SQLite. There are known issues with');
  INSERT INTO t1 VALUES('these older modules and their use should be');
  INSERT INTO t1 VALUES('avoided. Portions of the original FTS3 code were');
  INSERT INTO t1 VALUES('contributed to the SQLite project by Scott Hess of');
  INSERT INTO t1 VALUES('Google. It is now developed and maintained as part');
  INSERT INTO t1 VALUES('of SQLite. ');
}
fts3_tap_test 2.2 db t1
fts3_tap_test 2.2 db t1 {1 3 6}
do_execsql_test 2.3 { DELETE FROM t1 WHERE docid%2; }
fts3_tap_test 2.4 db t1
fts3_tap_test 2.4 db t1 {1 3 6}

do_execsql_test 2.5 { INSERT INTO t1(t1) VALUES('optimize') }
fts3_tap_test 2.6 db t1
fts3_tap_test 2.6 db t1 {1 3 6}

do_execsql_test 3.1 {
  CREATE VIRTUAL TABLE t2 USING fts4(prefix=1);
  CREATE VIRTUAL TABLE t2 USING fts4(prefix='1,2,3');
  INSERT INTO t2 VALUES('On 12 September the wind direction turned and');
  INSERT INTO t2 VALUES('William''s fleet sailed. A storm blew up and the');
  INSERT INTO t2 VALUES('fleet was forced to take shelter at');
  INSERT INTO t2 VALUES('Saint-Valery-sur-Somme and again wait for the wind');
  INSERT INTO t2 VALUES('to change. On 27 September the Norman fleet');
  INSERT INTO t2 VALUES('finally set sail, landing in England at Pevensey');
  INSERT INTO t2 VALUES('Bay (Sussex) on 28 September. William then moved');

  INSERT INTO t2 VALUES('Bay (Sussex) on 28 September. William then moved');
  INSERT INTO t2 VALUES('to Hastings, a few miles to the east, where he');
  INSERT INTO t2 VALUES('built a prefabricated wooden castle for a base of');
  INSERT INTO t2 VALUES('operations. From there, he ravaged the hinterland');
  INSERT INTO t2 VALUES('and waited for Harold''s return from the north.');
}

fts3_tap_test 3.2 db t2
fts3_tap_test 3.2 db t2 {1 2 3}
do_execsql_test 3.3 { SELECT optimize(t2) FROM t2 LIMIT 1 } {{Index optimized}}
fts3_tap_test 3.4 db t2
fts3_tap_test 3.4 db t2 {1 2 3}


#-------------------------------------------------------------------------
# Simple tests for reading the prefix-index.
#
do_execsql_test 4.1 {
  CREATE VIRTUAL TABLE t3 USING fts4(prefix=1);
  CREATE VIRTUAL TABLE t3 USING fts4(prefix="1,4");
  INSERT INTO t3 VALUES('one two three');
  INSERT INTO t3 VALUES('four five six');
  INSERT INTO t3 VALUES('seven eight nine');
}
do_execsql_test 4.2 {
  SELECT * FROM t3 WHERE t3 MATCH 'f*'
} {{four five six}}