[LUCENE-949] AnalyzingQueryParser can't work with leading wildcards.

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.2
• Fix Version/s: 4.4, 6.0
• Component/s: core/queryparser
• Lucene Fields: New, Patch Available
• Assignee: Steven Rowe
• Reporter: Stefan Klein
• Created: 03/Jul/07 12:41
• Updated: 28/Aug/22 11:39
• Resolved: 06/May/13 23:03

Description

The getWildcardQuery mehtod in AnalyzingQueryParser.java need the following changes to accept leading wildcards:

protected Query getWildcardQuery(String field, String termStr) throws ParseException
{
String useTermStr = termStr;
String leadingWildcard = null;
if ("*".equals(field))

{ if ("*".equals(useTermStr)) return new MatchAllDocsQuery(); }

boolean hasLeadingWildcard = (useTermStr.startsWith("*") || useTermStr.startsWith("?")) ? true : false;

if (!getAllowLeadingWildcard() && hasLeadingWildcard)
throw new ParseException("'*' or '?' not allowed as first character in WildcardQuery");

if (getLowercaseExpandedTerms())

{ useTermStr = useTermStr.toLowerCase(); }

if (hasLeadingWildcard)

{ leadingWildcard = useTermStr.substring(0, 1); useTermStr = useTermStr.substring(1); }

List tlist = new ArrayList();
List wlist = new ArrayList();
/*

• somewhat a hack: find/store wildcard chars in order to put them back
• after analyzing
  */
  boolean isWithinToken = (!useTermStr.startsWith("?") && !useTermStr.startsWith("*"));
  isWithinToken = true;
  StringBuffer tmpBuffer = new StringBuffer();
  char[] chars = useTermStr.toCharArray();
  for (int i = 0; i < useTermStr.length(); i++)
  {
  if (chars[i] == '?' || chars[i] == '*')
  Unknown macro: { if (isWithinToken) { tlist.add(tmpBuffer.toString()); tmpBuffer.setLength(0); } isWithinToken = false; }

  else

  Unknown macro: { if (!isWithinToken) { wlist.add(tmpBuffer.toString()); tmpBuffer.setLength(0); } isWithinToken = true; }

  tmpBuffer.append(chars[i]);
  }
  if (isWithinToken)

  { tlist.add(tmpBuffer.toString()); }

  else

  { wlist.add(tmpBuffer.toString()); }

// get Analyzer from superclass and tokenize the term
TokenStream source = getAnalyzer().tokenStream(field, new StringReader(useTermStr));
org.apache.lucene.analysis.Token t;

int countTokens = 0;
while (true)
{
try

{ t = source.next(); }

catch (IOException e)

{ t = null; }

if (t == null)

{ break; }

if (!"".equals(t.termText()))
{
try

{ tlist.set(countTokens++, t.termText()); }

catch (IndexOutOfBoundsException ioobe)

{ countTokens = -1; }

}
}
try

{ source.close(); }

catch (IOException e)

{ // ignore }

if (countTokens != tlist.size())

{ /* * this means that the analyzer used either added or consumed * (common for a stemmer) tokens, and we can't build a WildcardQuery */ throw new ParseException("Cannot build WildcardQuery with analyzer " + getAnalyzer().getClass() + " - tokens added or lost"); }

if (tlist.size() == 0)

{ return null; }

else if (tlist.size() == 1)
{
if (wlist.size() == 1)
{
/*

• if wlist contains one wildcard, it must be at the end,
• because: 1) wildcards at 1st position of a term by
• QueryParser where truncated 2) if wildcard was not in end,
• there would be two or more tokens
  */
  StringBuffer sb = new StringBuffer();
  if (hasLeadingWildcard) { // adding leadingWildcard sb.append(leadingWildcard); }
  sb.append((String) tlist.get(0));
  sb.append(wlist.get(0).toString());
  return super.getWildcardQuery(field, sb.toString());
  }
  else if (wlist.size() == 0 && hasLeadingWildcard)
  {
  /*
  * if wlist contains no wildcard, it must be at 1st position
  */
  StringBuffer sb = new StringBuffer();
  if (hasLeadingWildcard)
  { // adding leadingWildcard sb.append(leadingWildcard); }

  sb.append((String) tlist.get(0));
  sb.append(wlist.get(0).toString());
  return super.getWildcardQuery(field, sb.toString());
  }
  else

  { /* * we should never get here! if so, this method was called with * a termStr containing no wildcard ... */ throw new IllegalArgumentException("getWildcardQuery called without wildcard"); }

  }
  else
  {
  /*

• the term was tokenized, let's rebuild to one token with wildcards
• put back in postion
  */
  StringBuffer sb = new StringBuffer();
  if (hasLeadingWildcard) { // adding leadingWildcard sb.append(leadingWildcard); }

  for (int i = 0; i < tlist.size(); i++)

  Unknown macro: { sb.append((String) tlist.get(i)); if (wlist != null && wlist.size() > i) { sb.append((String) wlist.get(i)); } }

  return super.getWildcardQuery(field, sb.toString());
  }
  }