BLOCK_INSERT_STMT,
  BLOCK_SELECT_STMT,
  BLOCK_DELETE_STMT,

  SEGDIR_MAX_INDEX_STMT,
  SEGDIR_SET_STMT,
  SEGDIR_SELECT_STMT,
  SEGDIR_SPAN_STMT,
  SEGDIR_DELETE_STMT,

  SEGDIR_SELECT_ALL_STMT,

  MAX_STMT                     /* Always at end! */
} fulltext_statement;

/* These must exactly match the enum above. */
/* TODO(shess): Is there some risk that a statement will be used in two
................................................................................

  /* BLOCK_INSERT */ "insert into %_segments values (?)",
  /* BLOCK_SELECT */ "select block from %_segments where rowid = ?",
  /* BLOCK_DELETE */ "delete from %_segments where rowid between ? and ?",

  /* SEGDIR_MAX_INDEX */ "select max(idx) from %_segdir where level = ?",
  /* SEGDIR_SET */ "insert into %_segdir values (?, ?, ?, ?, ?, ?)",
  /* SEGDIR_SELECT */
  "select start_block, leaves_end_block, root from %_segdir "
  " where level = ? order by idx",
  /* SEGDIR_SPAN */
  "select min(start_block), max(end_block) from %_segdir "
  " where level = ? and start_block <> 0",
  /* SEGDIR_DELETE */ "delete from %_segdir where level = ?",







  /* SEGDIR_SELECT_ALL */

  "select root, leaves_end_block from %_segdir order by level desc, idx",
};

/*
** A connection to a fulltext index is an instance of the following
** structure.  The xCreate and xConnect methods create an instance
** of this structure and xDestroy and xDisconnect free that instance.
** All other methods receive a pointer to the structure as one of their
................................................................................
/* Initializes pReaders with the segments from level iLevel, returning
** the number of segments in *piReaders.  Leaves pReaders in sorted
** order.
*/
static int leavesReadersInit(fulltext_vtab *v, int iLevel,
                             LeavesReader *pReaders, int *piReaders){
  sqlite3_stmt *s;
  int i, rc = sql_get_statement(v, SEGDIR_SELECT_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_int(s, 1, iLevel);
  if( rc!=SQLITE_OK ) return rc;

  i = 0;
  while( (rc = sqlite3_step(s))==SQLITE_ROW ){
................................................................................

  dataBufferInit(&doclist, 0);

  /* Traverse the segments from oldest to newest so that newer doclist
  ** elements for given docids overwrite older elements.
  */
  while( (rc = sqlite3_step(s))==SQLITE_ROW ){
    const char *pData = sqlite3_column_blob(s, 0);
    const int nData = sqlite3_column_bytes(s, 0);
    const sqlite_int64 iLeavesEnd = sqlite3_column_int64(s, 1);
    rc = loadSegment(v, pData, nData, iLeavesEnd, pTerm, nTerm, isPrefix,
                     &doclist);
    if( rc!=SQLITE_OK ) goto err;
  }
  if( rc==SQLITE_DONE ){
    if( doclist.nData!=0 ){
................................................................................
    snippetOffsetText(&pCursor->snippet);
    sqlite3_result_text(pContext,
                        pCursor->snippet.zOffset, pCursor->snippet.nOffset,
                        SQLITE_STATIC);
  }
}





























































































































































































































































































































































































/*
** This routine implements the xFindFunction method for the FTS2
** virtual table.
*/
static int fulltextFindFunction(
  sqlite3_vtab *pVtab,
  int nArg,
................................................................................
){
  if( strcmp(zName,"snippet")==0 ){
    *pxFunc = snippetFunc;
    return 1;
  }else if( strcmp(zName,"offsets")==0 ){
    *pxFunc = snippetOffsetsFunc;
    return 1;














  }
  return 0;
}

/*
** Rename an fts2 table.
*/
................................................................................
  ** the two scalar functions. If this is successful, register the
  ** module with sqlite.
  */
  if( SQLITE_OK==rc 
   && SQLITE_OK==(rc = sqlite3Fts2InitHashTable(db, pHash, "fts2_tokenizer"))
   && SQLITE_OK==(rc = sqlite3_overload_function(db, "snippet", -1))
   && SQLITE_OK==(rc = sqlite3_overload_function(db, "offsets", -1))




  ){
    return sqlite3_create_module_v2(
        db, "fts2", &fts2Module, (void *)pHash, hashDestroy
    );
  }

  /* An error has occured. Delete the hash table and return the error code. */

  BLOCK_INSERT_STMT,
  BLOCK_SELECT_STMT,
  BLOCK_DELETE_STMT,

  SEGDIR_MAX_INDEX_STMT,
  SEGDIR_SET_STMT,
  SEGDIR_SELECT_LEVEL_STMT,
  SEGDIR_SPAN_STMT,
  SEGDIR_DELETE_STMT,
  SEGDIR_SELECT_SEGMENT_STMT,
  SEGDIR_SELECT_ALL_STMT,

  MAX_STMT                     /* Always at end! */
} fulltext_statement;

/* These must exactly match the enum above. */
/* TODO(shess): Is there some risk that a statement will be used in two
................................................................................

  /* BLOCK_INSERT */ "insert into %_segments values (?)",
  /* BLOCK_SELECT */ "select block from %_segments where rowid = ?",
  /* BLOCK_DELETE */ "delete from %_segments where rowid between ? and ?",

  /* SEGDIR_MAX_INDEX */ "select max(idx) from %_segdir where level = ?",
  /* SEGDIR_SET */ "insert into %_segdir values (?, ?, ?, ?, ?, ?)",
  /* SEGDIR_SELECT_LEVEL */
  "select start_block, leaves_end_block, root from %_segdir "
  " where level = ? order by idx",
  /* SEGDIR_SPAN */
  "select min(start_block), max(end_block) from %_segdir "
  " where level = ? and start_block <> 0",
  /* SEGDIR_DELETE */ "delete from %_segdir where level = ?",

  /* NOTE(shess): The first three results of the following two
  ** statements must match.
  */
  /* SEGDIR_SELECT_SEGMENT */
  "select start_block, leaves_end_block, root from %_segdir "
  " where level = ? and idx = ?",
  /* SEGDIR_SELECT_ALL */
  "select start_block, leaves_end_block, root from %_segdir "
  " order by level desc, idx asc",
};

/*
** A connection to a fulltext index is an instance of the following
** structure.  The xCreate and xConnect methods create an instance
** of this structure and xDestroy and xDisconnect free that instance.
** All other methods receive a pointer to the structure as one of their
................................................................................
/* Initializes pReaders with the segments from level iLevel, returning
** the number of segments in *piReaders.  Leaves pReaders in sorted
** order.
*/
static int leavesReadersInit(fulltext_vtab *v, int iLevel,
                             LeavesReader *pReaders, int *piReaders){
  sqlite3_stmt *s;
  int i, rc = sql_get_statement(v, SEGDIR_SELECT_LEVEL_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_int(s, 1, iLevel);
  if( rc!=SQLITE_OK ) return rc;

  i = 0;
  while( (rc = sqlite3_step(s))==SQLITE_ROW ){
................................................................................

  dataBufferInit(&doclist, 0);

  /* Traverse the segments from oldest to newest so that newer doclist
  ** elements for given docids overwrite older elements.
  */
  while( (rc = sqlite3_step(s))==SQLITE_ROW ){
    const char *pData = sqlite3_column_blob(s, 2);
    const int nData = sqlite3_column_bytes(s, 2);
    const sqlite_int64 iLeavesEnd = sqlite3_column_int64(s, 1);
    rc = loadSegment(v, pData, nData, iLeavesEnd, pTerm, nTerm, isPrefix,
                     &doclist);
    if( rc!=SQLITE_OK ) goto err;
  }
  if( rc==SQLITE_DONE ){
    if( doclist.nData!=0 ){
................................................................................
    snippetOffsetText(&pCursor->snippet);
    sqlite3_result_text(pContext,
                        pCursor->snippet.zOffset, pCursor->snippet.nOffset,
                        SQLITE_STATIC);
  }
}

#ifdef SQLITE_TEST
/* Generate an error of the form "<prefix>: <msg>".  If msg is NULL,
** pull the error from the context's db handle.
*/
static void generateError(sqlite3_context *pContext,
                          const char *prefix, const char *msg){
  char buf[512];
  if( msg==NULL ) msg = sqlite3_errmsg(sqlite3_context_db_handle(pContext));
  sqlite3_snprintf(sizeof(buf), buf, "%s: %s", prefix, msg);
  sqlite3_result_error(pContext, buf, -1);
}

/* Helper function to collect the set of terms in the segment into
** pTerms.  The segment is defined by the leaf nodes between
** iStartBlockid and iEndBlockid, inclusive, or by the contents of
** pRootData if iStartBlockid is 0 (in which case the entire segment
** fit in a leaf).
*/
static int collectSegmentTerms(fulltext_vtab *v, sqlite3_stmt *s,
                               fts2Hash *pTerms){
  const sqlite_int64 iStartBlockid = sqlite3_column_int64(s, 0);
  const sqlite_int64 iEndBlockid = sqlite3_column_int64(s, 1);
  const char *pRootData = sqlite3_column_blob(s, 2);
  const int nRootData = sqlite3_column_bytes(s, 2);
  LeavesReader reader;
  int rc = leavesReaderInit(v, 0, iStartBlockid, iEndBlockid,
                            pRootData, nRootData, &reader);
  if( rc!=SQLITE_OK ) return rc;

  while( rc==SQLITE_OK && !leavesReaderAtEnd(&reader) ){
    const char *pTerm = leavesReaderTerm(&reader);
    const int nTerm = leavesReaderTermBytes(&reader);
    void *oldValue = sqlite3Fts2HashFind(pTerms, pTerm, nTerm);
    void *newValue = (void *)((char *)oldValue+1);

    /* From the comment before sqlite3Fts2HashInsert in fts2_hash.c,
    ** the data value passed is returned in case of malloc failure.
    */
    if( newValue==sqlite3Fts2HashInsert(pTerms, pTerm, nTerm, newValue) ){
      rc = SQLITE_NOMEM;
    }else{
      rc = leavesReaderStep(v, &reader);
    }
  }

  leavesReaderDestroy(&reader);
  return rc;
}

/* Helper function to build the result string for dump_terms(). */
static int generateTermsResult(sqlite3_context *pContext, fts2Hash *pTerms){
  int iTerm, nTerms, nResultBytes, iByte;
  char *result;
  TermData *pData;
  fts2HashElem *e;

  /* Iterate pTerms to generate an array of terms in pData for
  ** sorting.
  */
  nTerms = fts2HashCount(pTerms);
  assert( nTerms>0 );
  pData = sqlite3_malloc(nTerms*sizeof(TermData));
  if( pData==NULL ) return SQLITE_NOMEM;

  nResultBytes = 0;
  for(iTerm = 0, e = fts2HashFirst(pTerms); e; iTerm++, e = fts2HashNext(e)){
    nResultBytes += fts2HashKeysize(e)+1;   /* Term plus trailing space */
    assert( iTerm<nTerms );
    pData[iTerm].pTerm = fts2HashKey(e);
    pData[iTerm].nTerm = fts2HashKeysize(e);
    pData[iTerm].pCollector = fts2HashData(e);  /* unused */
  }
  assert( iTerm==nTerms );

  assert( nResultBytes>0 );   /* nTerms>0, nResultsBytes must be, too. */
  result = sqlite3_malloc(nResultBytes);
  if( result==NULL ){
    sqlite3_free(pData);
    return SQLITE_NOMEM;
  }

  if( nTerms>1 ) qsort(pData, nTerms, sizeof(*pData), termDataCmp);

  /* Read the terms in order to build the result. */
  iByte = 0;
  for(iTerm=0; iTerm<nTerms; ++iTerm){
    memcpy(result+iByte, pData[iTerm].pTerm, pData[iTerm].nTerm);
    iByte += pData[iTerm].nTerm;
    result[iByte++] = ' ';
  }
  assert( iByte==nResultBytes );
  assert( result[nResultBytes-1]==' ' );
  result[nResultBytes-1] = '\0';

  /* Passes away ownership of result. */
  sqlite3_result_text(pContext, result, nResultBytes-1, sqlite3_free);
  sqlite3_free(pData);
  return SQLITE_OK;
}

/* Implements dump_terms() for use in inspecting the fts2 index from
** tests.  TEXT result containing the ordered list of terms joined by
** spaces.  dump_terms(t, level, idx) dumps the terms for the segment
** specified by level, idx (in %_segdir), while dump_terms(t) dumps
** all terms in the index.  In both cases t is the fts table's magic
** table-named column.
*/
static void dumpTermsFunc(
  sqlite3_context *pContext,
  int argc, sqlite3_value **argv
){
  fulltext_cursor *pCursor;
  if( argc!=3 && argc!=1 ){
    generateError(pContext, "dump_terms", "incorrect arguments");
  }else if( sqlite3_value_type(argv[0])!=SQLITE_BLOB ||
            sqlite3_value_bytes(argv[0])!=sizeof(pCursor) ){
    generateError(pContext, "dump_terms", "illegal first argument");
  }else{
    fulltext_vtab *v;
    fts2Hash terms;
    sqlite3_stmt *s = NULL;
    int rc;

    memcpy(&pCursor, sqlite3_value_blob(argv[0]), sizeof(pCursor));
    v = cursor_vtab(pCursor);

    /* If passed only the cursor column, get all segments.  Otherwise
    ** get the segment described by the following two arguments.
    */
    if( argc==1 ){
      rc = sql_get_statement(v, SEGDIR_SELECT_ALL_STMT, &s);
    }else{
      rc = sql_get_statement(v, SEGDIR_SELECT_SEGMENT_STMT, &s);
      if( rc==SQLITE_OK ){
        rc = sqlite3_bind_int(s, 1, sqlite3_value_int(argv[1]));
        if( rc==SQLITE_OK ){
          rc = sqlite3_bind_int(s, 2, sqlite3_value_int(argv[2]));
        }
      }
    }

    if( rc!=SQLITE_OK ){
      generateError(pContext, "dump_terms", NULL);
      return;
    }

    /* Collect the terms for each segment. */
    sqlite3Fts2HashInit(&terms, FTS2_HASH_STRING, 1);
    while( (rc = sqlite3_step(s))==SQLITE_ROW ){
      rc = collectSegmentTerms(v, s, &terms);
      if( rc!=SQLITE_OK ) break;
    }

    if( rc!=SQLITE_DONE ){
      sqlite3_reset(s);
      generateError(pContext, "dump_terms", NULL);
    }else{
      const int nTerms = fts2HashCount(&terms);
      if( nTerms>0 ){
        rc = generateTermsResult(pContext, &terms);
        if( rc==SQLITE_NOMEM ){
          generateError(pContext, "dump_terms", "out of memory");
        }else{
          assert( rc==SQLITE_OK );
        }
      }else if( argc==3 ){
        /* The specific segment asked for could not be found. */
        generateError(pContext, "dump_terms", "segment not found");
      }else{
        /* No segments found. */
        /* TODO(shess): It should be impossible to reach this.  This
        ** case can only happen for an empty table, in which case
        ** SQLite has no rows to call this function on.
        */
        sqlite3_result_null(pContext);
      }
    }
    sqlite3Fts2HashClear(&terms);
  }
}

/* Expand the DL_DEFAULT doclist in pData into a text result in
** pContext.
*/
static void createDoclistResult(sqlite3_context *pContext,
                                const char *pData, int nData){
  DataBuffer dump;
  DLReader dlReader;

  assert( pData!=NULL && nData>0 );

  dataBufferInit(&dump, 0);
  dlrInit(&dlReader, DL_DEFAULT, pData, nData);
  for( ; !dlrAtEnd(&dlReader); dlrStep(&dlReader) ){
    char buf[256];
    PLReader plReader;

    plrInit(&plReader, &dlReader);
    if( DL_DEFAULT==DL_DOCIDS || plrAtEnd(&plReader) ){
      sqlite3_snprintf(sizeof(buf), buf, "[%lld] ", dlrDocid(&dlReader));
      dataBufferAppend(&dump, buf, strlen(buf));
    }else{
      int iColumn = plrColumn(&plReader);

      sqlite3_snprintf(sizeof(buf), buf, "[%lld %d[",
                       dlrDocid(&dlReader), iColumn);
      dataBufferAppend(&dump, buf, strlen(buf));

      for( ; !plrAtEnd(&plReader); plrStep(&plReader) ){
        if( plrColumn(&plReader)!=iColumn ){
          iColumn = plrColumn(&plReader);
          sqlite3_snprintf(sizeof(buf), buf, "] %d[", iColumn);
          assert( dump.nData>0 );
          dump.nData--;                     /* Overwrite trailing space. */
          assert( dump.pData[dump.nData]==' ');
          dataBufferAppend(&dump, buf, strlen(buf));
        }
        if( DL_DEFAULT==DL_POSITIONS_OFFSETS ){
          sqlite3_snprintf(sizeof(buf), buf, "%d,%d,%d ",
                           plrPosition(&plReader),
                           plrStartOffset(&plReader), plrEndOffset(&plReader));
        }else if( DL_DEFAULT==DL_POSITIONS ){
          sqlite3_snprintf(sizeof(buf), buf, "%d ", plrPosition(&plReader));
        }else{
          assert( NULL=="Unhandled DL_DEFAULT value");
        }
        dataBufferAppend(&dump, buf, strlen(buf));
      }
      plrDestroy(&plReader);

      assert( dump.nData>0 );
      dump.nData--;                     /* Overwrite trailing space. */
      assert( dump.pData[dump.nData]==' ');
      dataBufferAppend(&dump, "]] ", 3);
    }
  }
  dlrDestroy(&dlReader);

  assert( dump.nData>0 );
  dump.nData--;                     /* Overwrite trailing space. */
  assert( dump.pData[dump.nData]==' ');
  dump.pData[dump.nData] = '\0';
  assert( dump.nData>0 );

  /* Passes ownership of dump's buffer to pContext. */
  sqlite3_result_text(pContext, dump.pData, dump.nData, sqlite3_free);
  dump.pData = NULL;
  dump.nData = dump.nCapacity = 0;
}

/* Implements dump_doclist() for use in inspecting the fts2 index from
** tests.  TEXT result containing a string representation of the
** doclist for the indicated term.  dump_doclist(t, term, level, idx)
** dumps the doclist for term from the segment specified by level, idx
** (in %_segdir), while dump_doclist(t, term) dumps the logical
** doclist for the term across all segments.  The per-segment doclist
** can contain deletions, while the full-index doclist will not
** (deletions are omitted).
**
** Result formats differ with the setting of DL_DEFAULTS.  Examples:
**
** DL_DOCIDS: [1] [3] [7]
** DL_POSITIONS: [1 0[0 4] 1[17]] [3 1[5]]
** DL_POSITIONS_OFFSETS: [1 0[0,0,3 4,23,26] 1[17,102,105]] [3 1[5,20,23]]
**
** In each case the number after the outer '[' is the docid.  In the
** latter two cases, the number before the inner '[' is the column
** associated with the values within.  For DL_POSITIONS the numbers
** within are the positions, for DL_POSITIONS_OFFSETS they are the
** position, the start offset, and the end offset.
*/
static void dumpDoclistFunc(
  sqlite3_context *pContext,
  int argc, sqlite3_value **argv
){
  fulltext_cursor *pCursor;
  if( argc!=2 && argc!=4 ){
    generateError(pContext, "dump_doclist", "incorrect arguments");
  }else if( sqlite3_value_type(argv[0])!=SQLITE_BLOB ||
            sqlite3_value_bytes(argv[0])!=sizeof(pCursor) ){
    generateError(pContext, "dump_doclist", "illegal first argument");
  }else if( sqlite3_value_text(argv[1])==NULL ||
            sqlite3_value_text(argv[1])[0]=='\0' ){
    generateError(pContext, "dump_doclist", "empty second argument");
  }else{
    const char *pTerm = (const char *)sqlite3_value_text(argv[1]);
    const int nTerm = strlen(pTerm);
    fulltext_vtab *v;
    int rc;
    DataBuffer doclist;

    memcpy(&pCursor, sqlite3_value_blob(argv[0]), sizeof(pCursor));
    v = cursor_vtab(pCursor);

    dataBufferInit(&doclist, 0);

    /* termSelect() yields the same logical doclist that queries are
    ** run against.
    */
    if( argc==2 ){
      rc = termSelect(v, v->nColumn, pTerm, nTerm, 0, DL_DEFAULT, &doclist);
    }else{
      sqlite3_stmt *s = NULL;

      /* Get our specific segment's information. */
      rc = sql_get_statement(v, SEGDIR_SELECT_SEGMENT_STMT, &s);
      if( rc==SQLITE_OK ){
        rc = sqlite3_bind_int(s, 1, sqlite3_value_int(argv[2]));
        if( rc==SQLITE_OK ){
          rc = sqlite3_bind_int(s, 2, sqlite3_value_int(argv[3]));
        }
      }

      if( rc==SQLITE_OK ){
        rc = sqlite3_step(s);

        if( rc==SQLITE_DONE ){
          dataBufferDestroy(&doclist);
          generateError(pContext, "dump_doclist", "segment not found");
          return;
        }

        /* Found a segment, load it into doclist. */
        if( rc==SQLITE_ROW ){
          const sqlite_int64 iLeavesEnd = sqlite3_column_int64(s, 1);
          const char *pData = sqlite3_column_blob(s, 2);
          const int nData = sqlite3_column_bytes(s, 2);

          /* loadSegment() is used by termSelect() to load each
          ** segment's data.
          */
          rc = loadSegment(v, pData, nData, iLeavesEnd, pTerm, nTerm, 0,
                           &doclist);
          if( rc==SQLITE_OK ){
            rc = sqlite3_step(s);

            /* Should not have more than one matching segment. */
            if( rc!=SQLITE_DONE ){
              sqlite3_reset(s);
              dataBufferDestroy(&doclist);
              generateError(pContext, "dump_doclist", "invalid segdir");
              return;
            }
            rc = SQLITE_OK;
          }
        }
      }

      sqlite3_reset(s);
    }

    if( rc==SQLITE_OK ){
      if( doclist.nData>0 ){
        createDoclistResult(pContext, doclist.pData, doclist.nData);
      }else{
        /* TODO(shess): This can happen if the term is not present, or
        ** if all instances of the term have been deleted and this is
        ** an all-index dump.  It may be interesting to distinguish
        ** these cases.
        */
        sqlite3_result_text(pContext, "", 0, SQLITE_STATIC);
      }
    }else if( rc==SQLITE_NOMEM ){
      /* Handle out-of-memory cases specially because if they are
      ** generated in fts2 code they may not be reflected in the db
      ** handle.
      */
      /* TODO(shess): Handle this more comprehensively.
      ** sqlite3ErrStr() has what I need, but is internal.
      */
      generateError(pContext, "dump_doclist", "out of memory");
    }else{
      generateError(pContext, "dump_doclist", NULL);
    }

    dataBufferDestroy(&doclist);
  }
}
#endif

/*
** This routine implements the xFindFunction method for the FTS2
** virtual table.
*/
static int fulltextFindFunction(
  sqlite3_vtab *pVtab,
  int nArg,
................................................................................
){
  if( strcmp(zName,"snippet")==0 ){
    *pxFunc = snippetFunc;
    return 1;
  }else if( strcmp(zName,"offsets")==0 ){
    *pxFunc = snippetOffsetsFunc;
    return 1;
#ifdef SQLITE_TEST
    /* NOTE(shess): These functions are present only for testing
    ** purposes.  No particular effort is made to optimize their
    ** execution or how they build their results.
    */
  }else if( strcmp(zName,"dump_terms")==0 ){
    /* fprintf(stderr, "Found dump_terms\n"); */
    *pxFunc = dumpTermsFunc;
    return 1;
  }else if( strcmp(zName,"dump_doclist")==0 ){
    /* fprintf(stderr, "Found dump_doclist\n"); */
    *pxFunc = dumpDoclistFunc;
    return 1;
#endif
  }
  return 0;
}

/*
** Rename an fts2 table.
*/
................................................................................
  ** the two scalar functions. If this is successful, register the
  ** module with sqlite.
  */
  if( SQLITE_OK==rc 
   && SQLITE_OK==(rc = sqlite3Fts2InitHashTable(db, pHash, "fts2_tokenizer"))
   && SQLITE_OK==(rc = sqlite3_overload_function(db, "snippet", -1))
   && SQLITE_OK==(rc = sqlite3_overload_function(db, "offsets", -1))
#ifdef SQLITE_TEST
   && SQLITE_OK==(rc = sqlite3_overload_function(db, "dump_terms", -1))
   && SQLITE_OK==(rc = sqlite3_overload_function(db, "dump_doclist", -1))
#endif
  ){
    return sqlite3_create_module_v2(
        db, "fts2", &fts2Module, (void *)pHash, hashDestroy
    );
  }

  /* An error has occured. Delete the hash table and return the error code. */

# 2008 June 26
#
# 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 exercises some new testing functions in the FTS2 module,
# and then uses them to do some basic tests that FTS2 is internally
# working as expected.
#
# $Id: fts2p.test,v 1.1 2008/07/22 23:32:28 shess Exp $
#

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

# If SQLITE_ENABLE_FTS2 is not defined, omit this file.
ifcapable !fts2 {
  finish_test
  return
}

#*************************************************************************
# Probe to see if support for these functions is compiled in.
# TODO(shess): Change main.mk to do the right thing and remove this test.
db eval {
  DROP TABLE IF EXISTS t1;
  CREATE VIRTUAL TABLE t1 USING fts2(c);
  INSERT INTO t1 (rowid, c) VALUES (1, 'x');
}

set s {SELECT dump_terms(t1, 1) FROM t1 LIMIT 1}
set r {1 {unable to use function dump_terms in the requested context}}
if {[catchsql $s]==$r} {
  finish_test
  return
}

#*************************************************************************
# Test that the new functions give appropriate errors.
do_test fts2p-0.0 {
  catchsql {
    SELECT dump_terms(t1, 1) FROM t1 LIMIT 1;
  }
} {1 {dump_terms: incorrect arguments}}

do_test fts2p-0.1 {
  catchsql {
    SELECT dump_terms(t1, 0, 0, 0) FROM t1 LIMIT 1;
  }
} {1 {dump_terms: incorrect arguments}}

do_test fts2p-0.2 {
  catchsql {
    SELECT dump_terms(1, t1) FROM t1 LIMIT 1;
  }
} {1 {unable to use function dump_terms in the requested context}}

do_test fts2p-0.3 {
  catchsql {
    SELECT dump_terms(t1, 16, 16) FROM t1 LIMIT 1;
  }
} {1 {dump_terms: segment not found}}

do_test fts2p-0.4 {
  catchsql {
    SELECT dump_doclist(t1) FROM t1 LIMIT 1;
  }
} {1 {dump_doclist: incorrect arguments}}

do_test fts2p-0.5 {
  catchsql {
    SELECT dump_doclist(t1, NULL) FROM t1 LIMIT 1;
  }
} {1 {dump_doclist: empty second argument}}

do_test fts2p-0.6 {
  catchsql {
    SELECT dump_doclist(t1, '') FROM t1 LIMIT 1;
  }
} {1 {dump_doclist: empty second argument}}

do_test fts2p-0.7 {
  catchsql {
    SELECT dump_doclist(t1, 'a', 0) FROM t1 LIMIT 1;
  }
} {1 {dump_doclist: incorrect arguments}}

do_test fts2p-0.8 {
  catchsql {
    SELECT dump_doclist(t1, 'a', 0, 0, 0) FROM t1 LIMIT 1;
  }
} {1 {dump_doclist: incorrect arguments}}

do_test fts2p-0.9 {
  catchsql {
    SELECT dump_doclist(t1, 'a', 16, 16) FROM t1 LIMIT 1;
  }
} {1 {dump_doclist: segment not found}}

#*************************************************************************
# Utility function to check for the expected terms in the segment
# level/index.  _all version does same but for entire index.
proc check_terms {test level index terms} {
  # TODO(shess): Figure out why uplevel in do_test can't catch
  # $level and $index directly.
  set ::level $level
  set ::index $index
  do_test $test.terms {
    execsql {
      SELECT dump_terms(t1, $::level, $::index) FROM t1 LIMIT 1;
    }
  } [list $terms]
}
proc check_terms_all {test terms} {
  do_test $test.terms {
    execsql {
      SELECT dump_terms(t1) FROM t1 LIMIT 1;
    }
  } [list $terms]
}

# Utility function to check for the expected doclist for the term in
# segment level/index.  _all version does same for entire index.
proc check_doclist {test level index term doclist} {
  # TODO(shess): Again, why can't the non-:: versions work?
  set ::term $term
  set ::level $level
  set ::index $index
  do_test $test {
    execsql {
      SELECT dump_doclist(t1, $::term, $::level, $::index) FROM t1 LIMIT 1;
    }
  } [list $doclist]
}
proc check_doclist_all {test term doclist} {
  set ::term $term
  do_test $test {
    execsql {
      SELECT dump_doclist(t1, $::term) FROM t1 LIMIT 1;
    }
  } [list $doclist]
}

#*************************************************************************
# Test the segments resulting from straight-forward inserts.
db eval {
  DROP TABLE IF EXISTS t1;
  CREATE VIRTUAL TABLE t1 USING fts2(c);
  INSERT INTO t1 (rowid, c) VALUES (1, 'This is a test');
  INSERT INTO t1 (rowid, c) VALUES (2, 'That was a test');
  INSERT INTO t1 (rowid, c) VALUES (3, 'This is a test');
}

# Check for expected segments and expected matches.
do_test fts2p-1.0.segments {
  execsql {
    SELECT level, idx FROM t1_segdir ORDER BY level, idx;
  }
} {0 0 0 1 0 2}
do_test fts2p-1.0.matches {
  execsql {
    SELECT OFFSETS(t1) FROM t1
     WHERE t1 MATCH 'this OR that OR was OR a OR is OR test' ORDER BY rowid;
  }
} [list {0 0 0 4 0 4 5 2 0 3 8 1 0 5 10 4} \
        {0 1 0 4 0 2 5 3 0 3 9 1 0 5 11 4} \
        {0 0 0 4 0 4 5 2 0 3 8 1 0 5 10 4}]

# Check the specifics of the segments constructed.
# Logical view of entire index.
check_terms_all   fts2p-1.0.1   {a is test that this was}
check_doclist_all fts2p-1.0.1.1 a {[1 0[2]] [2 0[2]] [3 0[2]]}
check_doclist_all fts2p-1.0.1.2 is {[1 0[1]] [3 0[1]]}
check_doclist_all fts2p-1.0.1.3 test {[1 0[3]] [2 0[3]] [3 0[3]]}
check_doclist_all fts2p-1.0.1.4 that {[2 0[0]]}
check_doclist_all fts2p-1.0.1.5 this {[1 0[0]] [3 0[0]]}
check_doclist_all fts2p-1.0.1.6 was {[2 0[1]]}

# Segment 0,0
check_terms   fts2p-1.0.2   0 0 {a is test this}
check_doclist fts2p-1.0.2.1 0 0 a {[1 0[2]]}
check_doclist fts2p-1.0.2.2 0 0 is {[1 0[1]]}
check_doclist fts2p-1.0.2.3 0 0 test {[1 0[3]]}
check_doclist fts2p-1.0.2.4 0 0 this {[1 0[0]]}

# Segment 0,1
check_terms   fts2p-1.0.3   0 1 {a test that was}
check_doclist fts2p-1.0.3.1 0 1 a {[2 0[2]]}
check_doclist fts2p-1.0.3.2 0 1 test {[2 0[3]]}
check_doclist fts2p-1.0.3.3 0 1 that {[2 0[0]]}
check_doclist fts2p-1.0.3.4 0 1 was {[2 0[1]]}

# Segment 0,2
check_terms   fts2p-1.0.4   0 2 {a is test this}
check_doclist fts2p-1.0.4.1 0 2 a {[3 0[2]]}
check_doclist fts2p-1.0.4.2 0 2 is {[3 0[1]]}
check_doclist fts2p-1.0.4.3 0 2 test {[3 0[3]]}
check_doclist fts2p-1.0.4.4 0 2 this {[3 0[0]]}

#*************************************************************************
# Test the segments resulting from inserts followed by a delete.
db eval {
  DROP TABLE IF EXISTS t1;
  CREATE VIRTUAL TABLE t1 USING fts2(c);
  INSERT INTO t1 (rowid, c) VALUES (1, 'This is a test');
  INSERT INTO t1 (rowid, c) VALUES (2, 'That was a test');
  INSERT INTO t1 (rowid, c) VALUES (3, 'This is a test');
  DELETE FROM t1 WHERE rowid = 1;
}

do_test fts2p-1.1.segments {
  execsql {
    SELECT level, idx FROM t1_segdir ORDER BY level, idx;
  }
} {0 0 0 1 0 2 0 3}
do_test fts2p-1.1.matches {
  execsql {
    SELECT OFFSETS(t1) FROM t1
     WHERE t1 MATCH 'this OR that OR was OR a OR is OR test' ORDER BY rowid;
  }
} {{0 1 0 4 0 2 5 3 0 3 9 1 0 5 11 4} {0 0 0 4 0 4 5 2 0 3 8 1 0 5 10 4}}

check_terms_all fts2p-1.1.1 {a is test that this was}
check_doclist_all fts2p-1.1.1.1 a {[2 0[2]] [3 0[2]]}
check_doclist_all fts2p-1.1.1.2 is {[3 0[1]]}
check_doclist_all fts2p-1.1.1.3 test {[2 0[3]] [3 0[3]]}
check_doclist_all fts2p-1.1.1.4 that {[2 0[0]]}
check_doclist_all fts2p-1.1.1.5 this {[3 0[0]]}
check_doclist_all fts2p-1.1.1.6 was {[2 0[1]]}

check_terms fts2p-1.1.2 0 0 {a is test this}
check_doclist fts2p-1.1.2.1 0 0 a {[1 0[2]]}
check_doclist fts2p-1.1.2.2 0 0 is {[1 0[1]]}
check_doclist fts2p-1.1.2.3 0 0 test {[1 0[3]]}
check_doclist fts2p-1.1.2.4 0 0 this {[1 0[0]]}

check_terms fts2p-1.1.3 0 1 {a test that was}
check_doclist fts2p-1.1.3.1 0 1 a {[2 0[2]]}
check_doclist fts2p-1.1.3.2 0 1 test {[2 0[3]]}
check_doclist fts2p-1.1.3.3 0 1 that {[2 0[0]]}
check_doclist fts2p-1.1.3.4 0 1 was {[2 0[1]]}

check_terms fts2p-1.1.4 0 2 {a is test this}
check_doclist fts2p-1.1.4.1 0 2 a {[3 0[2]]}
check_doclist fts2p-1.1.4.2 0 2 is {[3 0[1]]}
check_doclist fts2p-1.1.4.3 0 2 test {[3 0[3]]}
check_doclist fts2p-1.1.4.4 0 2 this {[3 0[0]]}

check_terms fts2p-1.1.5 0 3 {a is test this}
check_doclist fts2p-1.1.5.1 0 3 a {[1]}
check_doclist fts2p-1.1.5.2 0 3 is {[1]}
check_doclist fts2p-1.1.5.3 0 3 test {[1]}
check_doclist fts2p-1.1.5.4 0 3 this {[1]}

#*************************************************************************
# Test results when all references to certain tokens are deleted.
db eval {
  DROP TABLE IF EXISTS t1;
  CREATE VIRTUAL TABLE t1 USING fts2(c);
  INSERT INTO t1 (rowid, c) VALUES (1, 'This is a test');
  INSERT INTO t1 (rowid, c) VALUES (2, 'That was a test');
  INSERT INTO t1 (rowid, c) VALUES (3, 'This is a test');
  DELETE FROM t1 WHERE rowid IN (1,3);
}

# Still 4 segments because 0,3 will contain deletes for rowid 1 and 3.
do_test fts2p-1.2.segments {
  execsql {
    SELECT level, idx FROM t1_segdir ORDER BY level, idx;
  }
} {0 0 0 1 0 2 0 3}
do_test fts2p-1.2.matches {
  execsql {
    SELECT OFFSETS(t1) FROM t1
     WHERE t1 MATCH 'this OR that OR was OR a OR is OR test' ORDER BY rowid;
  }
} {{0 1 0 4 0 2 5 3 0 3 9 1 0 5 11 4}}

check_terms_all fts2p-1.2.1 {a is test that this was}
check_doclist_all fts2p-1.2.1.1 a {[2 0[2]]}
check_doclist_all fts2p-1.2.1.2 is {}
check_doclist_all fts2p-1.2.1.3 test {[2 0[3]]}
check_doclist_all fts2p-1.2.1.4 that {[2 0[0]]}
check_doclist_all fts2p-1.2.1.5 this {}
check_doclist_all fts2p-1.2.1.6 was {[2 0[1]]}

check_terms fts2p-1.2.2 0 0 {a is test this}
check_doclist fts2p-1.2.2.1 0 0 a {[1 0[2]]}
check_doclist fts2p-1.2.2.2 0 0 is {[1 0[1]]}
check_doclist fts2p-1.2.2.3 0 0 test {[1 0[3]]}
check_doclist fts2p-1.2.2.4 0 0 this {[1 0[0]]}

check_terms fts2p-1.2.3 0 1 {a test that was}
check_doclist fts2p-1.2.3.1 0 1 a {[2 0[2]]}
check_doclist fts2p-1.2.3.2 0 1 test {[2 0[3]]}
check_doclist fts2p-1.2.3.3 0 1 that {[2 0[0]]}
check_doclist fts2p-1.2.3.4 0 1 was {[2 0[1]]}

check_terms fts2p-1.2.4 0 2 {a is test this}
check_doclist fts2p-1.2.4.1 0 2 a {[3 0[2]]}
check_doclist fts2p-1.2.4.2 0 2 is {[3 0[1]]}
check_doclist fts2p-1.2.4.3 0 2 test {[3 0[3]]}
check_doclist fts2p-1.2.4.4 0 2 this {[3 0[0]]}

check_terms fts2p-1.2.5 0 3 {a is test this}
check_doclist fts2p-1.2.5.1 0 3 a {[1] [3]}
check_doclist fts2p-1.2.5.2 0 3 is {[1] [3]}
check_doclist fts2p-1.2.5.3 0 3 test {[1] [3]}
check_doclist fts2p-1.2.5.4 0 3 this {[1] [3]}

#*************************************************************************
# Test results when everything is optimized manually.
db eval {
  DROP TABLE IF EXISTS t1;
  CREATE VIRTUAL TABLE t1 USING fts2(c);
  INSERT INTO t1 (rowid, c) VALUES (1, 'This is a test');
  INSERT INTO t1 (rowid, c) VALUES (2, 'That was a test');
  INSERT INTO t1 (rowid, c) VALUES (3, 'This is a test');
  DELETE FROM t1 WHERE rowid IN (1,3);
  DROP TABLE IF EXISTS t1old;
  ALTER TABLE t1 RENAME TO t1old;
  CREATE VIRTUAL TABLE t1 USING fts2(c);
  INSERT INTO t1 (rowid, c) SELECT rowid, c FROM t1old;
  DROP TABLE t1old;
}

# Should be a single optimal segment with the same logical results.
do_test fts2p-1.3.segments {
  execsql {
    SELECT level, idx FROM t1_segdir ORDER BY level, idx;
  }
} {0 0}
do_test fts2p-1.3.matches {
  execsql {
    SELECT OFFSETS(t1) FROM t1
     WHERE t1 MATCH 'this OR that OR was OR a OR is OR test' ORDER BY rowid;
  }
} {{0 1 0 4 0 2 5 3 0 3 9 1 0 5 11 4}}

check_terms_all fts2p-1.3.1 {a test that was}
check_doclist_all fts2p-1.3.1.1 a {[2 0[2]]}
check_doclist_all fts2p-1.3.1.2 test {[2 0[3]]}
check_doclist_all fts2p-1.3.1.3 that {[2 0[0]]}
check_doclist_all fts2p-1.3.1.4 was {[2 0[1]]}

check_terms fts2p-1.3.2 0 0 {a test that was}
check_doclist fts2p-1.3.2.1 0 0 a {[2 0[2]]}
check_doclist fts2p-1.3.2.2 0 0 test {[2 0[3]]}
check_doclist fts2p-1.3.2.3 0 0 that {[2 0[0]]}
check_doclist fts2p-1.3.2.4 0 0 was {[2 0[1]]}

finish_test