SQLite

** moves *ppPoslist so that it instead points to the first byte of the
** same position list.
*/
static void fts3ReversePoslist(char *pStart, char **ppPoslist){
  char *p = &(*ppPoslist)[-2];
  char c = 0;

  /* Skip backwards passed any trailing 0x00 bytes added by NearTrim() */
  while( p>pStart && (c=*p--)==0 );

  /* Search backwards for a varint with value zero (the end of the previous 
  ** poslist). This is an 0x00 byte preceded by some byte that does not
  ** have the 0x80 bit set.  */
  while( p>pStart && (*p & 0x80) | c ){ 
    c = *p--; 
  }
  assert( p==pStart || c==0 );

  /* At this point p points to that preceding byte without the 0x80 bit
  ** set. So to find the start of the poslist, skip forward 2 bytes then
  ** over a varint. 
  **
  ** Normally. The other case is that p==pStart and the poslist to return
  ** is the first in the doclist. In this case do not skip forward 2 bytes.
  ** The second part of the if condition (c==0 && *ppPoslist>&p[2])
  ** is required for cases where the first byte of a doclist and the
  ** doclist is empty. For example, if the first docid is 10, a doclist
  ** that begins with:
  **
  **   0x0A 0x00 <next docid delta varint>
  */
  if( p>pStart || (c==0 && *ppPoslist>&p[2]) ){ p = &p[2]; }
  while( *p++&0x80 );
  *ppPoslist = p;
}

/*
** Helper function used by the implementation of the overloaded snippet(),
** offsets() and optimize() SQL functions.

# focus of this script is testing the FTS3 module.
#
# $Id: fts3aa.test,v 1.1 2007/08/20 17:38:42 shess Exp $
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix fts3aa

# If SQLITE_ENABLE_FTS3 is defined, omit this file.
ifcapable !fts3 {
  finish_test
  return
}

do_execsql_test fts3aa-7.4 {
  CREATE VIRTUAL TABLE t3 USING fts3(tokenize=simple, tokenize=simple);
  SELECT tokenize FROM t3;
} {}
do_catchsql_test fts3aa-7.5 {
  CREATE VIRTUAL TABLE t4 USING fts4(tokenize=simple, tokenize=simple);
} {1 {unrecognized parameter: tokenize=simple}}

do_execsql_test 8.0 {
  CREATE VIRTUAL TABLE t0 USING fts4(order=desc);
  BEGIN;
  INSERT INTO t0(rowid, content) VALUES(1, 'abc');
  UPDATE t0 SET docid=5 WHERE docid=1;
  INSERT INTO t0(rowid, content) VALUES(6, 'abc');
}
do_execsql_test 8.1 {
  SELECT docid FROM t0 WHERE t0 MATCH 'abc';
} {6 5}
do_execsql_test 8.2 {
  SELECT docid FROM t0 WHERE t0 MATCH '"abc abc"';
} {}
do_execsql_test 8.3 { COMMIT }
do_execsql_test 8.4 {
  SELECT docid FROM t0 WHERE t0 MATCH 'abc';
} {6 5}
do_execsql_test 8.5 {
  SELECT docid FROM t0 WHERE t0 MATCH '"abc abc"';
} {}


finish_test