SQLite

struct Fts3auxCursor {
  sqlite3_vtab_cursor base;       /* Base class used by SQLite core */
  Fts3MultiSegReader csr;        /* Must be right after "base" */
  Fts3SegFilter filter;
  char *zStop;
  int nStop;                      /* Byte-length of string zStop */
  int iLangid;                    /* Language id to query */
  int isEof;                      /* True if cursor is at EOF */
  sqlite3_int64 iRowid;           /* Current rowid */

  int iCol;                       /* Current value of 'col' column */
  int nStat;                      /* Size of aStat[] array */
  struct Fts3auxColstats {
    sqlite3_int64 nDoc;           /* 'documents' values for current csr row */
    sqlite3_int64 nOcc;           /* 'occurrences' values for current csr row */
  } *aStat;
};

/*
** Schema of the terms table.
*/
#define FTS3_AUX_SCHEMA \
  "CREATE TABLE x(term, col, documents, occurrences, languageid HIDDEN)"

/*
** This function does all the work for both the xConnect and xCreate methods.
** These tables have no persistent representation of their own, so xConnect
** and xCreate are identical operations.
*/
static int fts3auxConnectMethod(

      goto bad_args;
    }
  }else{
    zFts3 = argv[3];
  }
  nFts3 = (int)strlen(zFts3);

  rc = sqlite3_declare_vtab(db, FTS3_AUX_SCHEMA);
  if( rc!=SQLITE_OK ) return rc;

  nByte = sizeof(Fts3auxTable) + sizeof(Fts3Table) + nDb + nFts3 + 2;
  p = (Fts3auxTable *)sqlite3_malloc(nByte);
  if( !p ) return SQLITE_NOMEM;
  memset(p, 0, nByte);

  sqlite3_vtab *pVTab, 
  sqlite3_index_info *pInfo
){
  int i;
  int iEq = -1;
  int iGe = -1;
  int iLe = -1;
  int iLangid = -1;
  int iNext = 1;                  /* Next free argvIndex value */

  UNUSED_PARAMETER(pVTab);

  /* This vtab delivers always results in "ORDER BY term ASC" order. */
  if( pInfo->nOrderBy==1 
   && pInfo->aOrderBy[0].iColumn==0 
   && pInfo->aOrderBy[0].desc==0
  ){
    pInfo->orderByConsumed = 1;
  }

  /* Search for equality and range constraints on the "term" column. 
  ** And equality constraints on the hidden "languageid" column. */
  for(i=0; i<pInfo->nConstraint; i++){
    if( pInfo->aConstraint[i].usable ){
      int op = pInfo->aConstraint[i].op;
      int iCol = pInfo->aConstraint[i].iColumn;

      if( iCol==0 ){
        if( op==SQLITE_INDEX_CONSTRAINT_EQ ) iEq = i;
        if( op==SQLITE_INDEX_CONSTRAINT_LT ) iLe = i;
        if( op==SQLITE_INDEX_CONSTRAINT_LE ) iLe = i;
        if( op==SQLITE_INDEX_CONSTRAINT_GT ) iGe = i;
        if( op==SQLITE_INDEX_CONSTRAINT_GE ) iGe = i;
      }
      if( iCol==4 ){
        if( op==SQLITE_INDEX_CONSTRAINT_EQ ) iLangid = i;
      }
    }
  }

  if( iEq>=0 ){
    pInfo->idxNum = FTS4AUX_EQ_CONSTRAINT;
    pInfo->aConstraintUsage[iEq].argvIndex = iNext++;
    pInfo->estimatedCost = 5;
  }else{
    pInfo->idxNum = 0;
    pInfo->estimatedCost = 20000;
    if( iGe>=0 ){
      pInfo->idxNum += FTS4AUX_GE_CONSTRAINT;
      pInfo->aConstraintUsage[iGe].argvIndex = iNext++;
      pInfo->estimatedCost /= 2;
    }
    if( iLe>=0 ){
      pInfo->idxNum += FTS4AUX_LE_CONSTRAINT;
      pInfo->aConstraintUsage[iLe].argvIndex = iNext++;
      pInfo->estimatedCost /= 2;
    }
  }
  if( iLangid>=0 ){
    pInfo->aConstraintUsage[iLangid].argvIndex = iNext++;
    pInfo->estimatedCost--;
  }

  return SQLITE_OK;
}

/*
** xOpen - Open a cursor.
*/

  const char *idxStr,             /* Unused */
  int nVal,                       /* Number of elements in apVal */
  sqlite3_value **apVal           /* Arguments for the indexing scheme */
){
  Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor;
  Fts3Table *pFts3 = ((Fts3auxTable *)pCursor->pVtab)->pFts3Tab;
  int rc;
  int isScan = 0;
  int iLangVal = 0;               /* Language id to query */

  int iEq = -1;                   /* Index of term=? value in apVal */
  int iGe = -1;                   /* Index of term>=? value in apVal */
  int iLe = -1;                   /* Index of term<=? value in apVal */
  int iLangid = -1;               /* Index of languageid=? value in apVal */
  int iNext = 0;

  UNUSED_PARAMETER(nVal);
  UNUSED_PARAMETER(idxStr);

  assert( idxStr==0 );
  assert( idxNum==FTS4AUX_EQ_CONSTRAINT || idxNum==0
       || idxNum==FTS4AUX_LE_CONSTRAINT || idxNum==FTS4AUX_GE_CONSTRAINT
       || idxNum==(FTS4AUX_LE_CONSTRAINT|FTS4AUX_GE_CONSTRAINT)
  );

  if( idxNum==FTS4AUX_EQ_CONSTRAINT ){
    iEq = iNext++;
  }else{
    isScan = 1;
    if( idxNum & FTS4AUX_GE_CONSTRAINT ){
      iGe = iNext++;
    }
    if( idxNum & FTS4AUX_LE_CONSTRAINT ){
      iLe = iNext++;
    }
  }
  if( iNext<nVal ){
    iLangid = iNext++;
  }

  /* In case this cursor is being reused, close and zero it. */
  testcase(pCsr->filter.zTerm);
  sqlite3Fts3SegReaderFinish(&pCsr->csr);
  sqlite3_free((void *)pCsr->filter.zTerm);
  sqlite3_free(pCsr->aStat);
  memset(&pCsr->csr, 0, ((u8*)&pCsr[1]) - (u8*)&pCsr->csr);

  pCsr->filter.flags = FTS3_SEGMENT_REQUIRE_POS|FTS3_SEGMENT_IGNORE_EMPTY;
  if( isScan ) pCsr->filter.flags |= FTS3_SEGMENT_SCAN;

  if( iEq>=0 || iGe>=0 ){
    const unsigned char *zStr = sqlite3_value_text(apVal[0]);
    assert( (iEq==0 && iGe==-1) || (iEq==-1 && iGe==0) );
    if( zStr ){
      pCsr->filter.zTerm = sqlite3_mprintf("%s", zStr);
      pCsr->filter.nTerm = sqlite3_value_bytes(apVal[0]);
      if( pCsr->filter.zTerm==0 ) return SQLITE_NOMEM;
    }
  }

  if( iLe>=0 ){
    pCsr->zStop = sqlite3_mprintf("%s", sqlite3_value_text(apVal[iLe]));
    pCsr->nStop = sqlite3_value_bytes(apVal[iLe]);
    if( pCsr->zStop==0 ) return SQLITE_NOMEM;
  }
  
  if( iLangid>=0 ){
    iLangVal = sqlite3_value_int(apVal[iLangid]);

    /* If the user specified a negative value for the languageid, use zero
    ** instead. This works, as the "languageid=?" constraint will also
    ** be tested by the VDBE layer. The test will always be false (since
    ** this module will not return a row with a negative languageid), and
    ** so the overall query will return zero rows.  */
    if( iLangVal<0 ) iLangVal = 0;
  }
  pCsr->iLangid = iLangVal;

  rc = sqlite3Fts3SegReaderCursor(pFts3, iLangVal, 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);

}

/*
** xColumn - Return a column value.
*/
static int fts3auxColumnMethod(
  sqlite3_vtab_cursor *pCursor,   /* Cursor to retrieve value from */
  sqlite3_context *pCtx,          /* Context for sqlite3_result_xxx() calls */
  int iCol                        /* Index of column to read value from */
){
  Fts3auxCursor *p = (Fts3auxCursor *)pCursor;

  assert( p->isEof==0 );
  switch( iCol ){
    case 0: /* term */
      sqlite3_result_text(pCtx, p->csr.zTerm, p->csr.nTerm, SQLITE_TRANSIENT);
      break;

    case 1: /* col */
      if( p->iCol ){
        sqlite3_result_int(pCtx, p->iCol-1);
      }else{
        sqlite3_result_text(pCtx, "*", -1, SQLITE_STATIC);
      }
      break;

    case 2: /* documents */
      sqlite3_result_int64(pCtx, p->aStat[p->iCol].nDoc);
      break;

    case 3: /* occurrences */
      sqlite3_result_int64(pCtx, p->aStat[p->iCol].nOcc);
      break;

    default: /* languageid */
      assert( iCol==4 );
      sqlite3_result_int(pCtx, p->iLangid);
      break;
  }

  return SQLITE_OK;
}

/*
** xRowid - Return the current rowid for the cursor.

# 2011 January 27
#
# 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 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
ifcapable !fts3 { finish_test ; return }
set ::testprefix fts3aux2

do_execsql_test 1.1 {
  CREATE VIRTUAL TABLE t1 USING fts4(a, b, languageid=l);
  INSERT INTO t1(a, b, l) VALUES
    ('zero zero', 'zero zero', 0),
    ('one two', 'three four', 1),
    ('five six', 'seven eight', 2)
  ;
  CREATE VIRTUAL TABLE terms USING fts4aux(t1);
} {}

do_execsql_test 1.2.1 {
  SELECT term, documents, occurrences, languageid FROM terms WHERE col = '*';
} {zero 1 4 0}

do_execsql_test 1.2.2 {
  SELECT * FROM terms;
} {zero * 1 4 zero 0 1 2 zero 1 1 2}

do_execsql_test 1.2.3 {
  SELECT * FROM terms WHERE languageid='';
} {}

do_execsql_test 1.2.4 {
  SELECT * FROM terms WHERE languageid=-1;
} {}

do_execsql_test 1.2.5 {
  SELECT * FROM terms WHERE languageid=9223372036854775807;
} {}

do_execsql_test 1.2.6 {
  SELECT * FROM terms WHERE languageid=-9223372036854775808;
} {}

do_execsql_test 1.2.7 {
  SELECT * FROM terms WHERE languageid=NULL;
} {}

do_execsql_test 1.3.1 {
  SELECT term, documents, occurrences, languageid 
  FROM terms WHERE col = '*' AND languageid=1;
} {
  four 1 1 1 one 1 1 1 three 1 1 1 two 1 1 1 
}

do_execsql_test 1.3.2 {
  SELECT term, col, documents, occurrences, languageid 
  FROM terms WHERE languageid=1;
} {
  four * 1 1 1   four 1 1 1 1 
  one * 1 1 1    one 0 1 1 1 
  three * 1 1 1  three 1 1 1 1 
  two * 1 1 1    two 0 1 1 1 
}

do_execsql_test 1.3.3 {
  SELECT term, col, documents, occurrences, languageid 
  FROM terms WHERE languageid=1 AND term='zero'
} {
}

do_execsql_test 1.3.4 {
  SELECT term, col, documents, occurrences, languageid 
  FROM terms WHERE languageid='1' AND term='two'
} {
  two * 1 1 1    two 0 1 1 1 
}

do_execsql_test 1.3.5 {
  SELECT term, col, documents, occurrences, languageid 
  FROM terms WHERE languageid='+1' AND term>'four'
} {
  one * 1 1 1    one 0 1 1 1 
  three * 1 1 1  three 1 1 1 1 
  two * 1 1 1    two 0 1 1 1 
}

do_execsql_test 1.4.1 {
  SELECT term, documents, occurrences, languageid 
  FROM terms WHERE col = '*' AND languageid=2;
} {
  eight 1 1 2 five 1 1 2 seven 1 1 2 six 1 1 2
}

do_execsql_test 1.4.2 {
  SELECT term, col, documents, occurrences, languageid 
  FROM terms WHERE languageid=2;
} {
  eight * 1 1 2    eight 1 1 1 2 
  five * 1 1 2     five 0 1 1 2 
  seven * 1 1 2    seven 1 1 1 2 
  six * 1 1 2      six 0 1 1 2
}

do_execsql_test 1.4.3 {
  SELECT term, col, documents, occurrences, languageid 
  FROM terms WHERE languageid=2 AND term='five';
} {
  five * 1 1 2     five 0 1 1 2 
}

do_execsql_test 1.4.4 {
  SELECT term, col, documents, occurrences, languageid 
  FROM terms WHERE term='five' AND languageid=2 
} {
  five * 1 1 2     five 0 1 1 2 
}

do_execsql_test 1.4.5 {
  SELECT term, col, documents, occurrences, languageid 
  FROM terms WHERE term>='seven' AND languageid=2
} {
  seven * 1 1 2    seven 1 1 1 2 
  six * 1 1 2      six 0 1 1 2
}

do_execsql_test 1.4.6 {
  SELECT term, col, documents, occurrences, languageid 
  FROM terms WHERE term>='e' AND term<'seven' AND languageid=2
} {
  eight * 1 1 2    eight 1 1 1 2 
  five * 1 1 2     five 0 1 1 2 
}

finish_test