/*
* eXist Open Source Native XML Database
* Copyright (C) 2002-2009 The eXist Project
* http://exist-db.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $Id$
*/
package org.exist.xquery.functions;
import org.apache.log4j.Logger;
import java.util.Iterator;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;
import org.exist.EXistException;
import org.exist.fulltext.FTIndex;
import org.exist.dom.ExtArrayNodeSet;
import org.exist.dom.NodeProxy;
import org.exist.dom.NodeSet;
import org.exist.storage.NativeTextEngine;
import org.exist.storage.TextSearchEngine;
import org.exist.storage.analysis.TextToken;
import org.exist.storage.analysis.Tokenizer;
import org.exist.util.GlobToRegex;
import org.exist.xquery.*;
import org.exist.xquery.util.ExpressionDumper;
import org.exist.xquery.value.IntegerValue;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.Type;
/**
* text:near() function.
*
* @author Wolfgang Meier <wolfgang@exist-db.org> (July 31, 2002)
*/
public class ExtNear extends ExtFulltext {
private static final Logger logger = Logger.getLogger(ExtNear.class);
private int min_distance = 1;
private int max_distance = 1;
private Expression minDistance = null;
private Expression maxDistance = null;
public ExtNear(XQueryContext context) {
super(context, Constants.FULLTEXT_AND);
}
/* (non-Javadoc)
* @see org.exist.xquery.functions.ExtFulltext#analyze(org.exist.xquery.AnalyzeContextInfo)
*/
public void analyze(AnalyzeContextInfo contextInfo)
throws XPathException {
AnalyzeContextInfo newContextInfo = new AnalyzeContextInfo(contextInfo);
super.analyze(newContextInfo);
if (maxDistance != null) {
maxDistance.analyze(newContextInfo);
}
if (minDistance != null) {
minDistance.analyze(newContextInfo);
}
}
public NodeSet preSelect(Sequence contextSequence, boolean useContext)
throws XPathException {
// Can return NPE
TextSearchEngine engine = context.getBroker().getTextEngine();
if(engine==null){
throw new XPathException("The legacy fulltext indexing has been disabled by "
+ "default from version 1.4.1. Please consider migrating to "
+ "the new full text indexing..");
}
long start = System.currentTimeMillis();
// the expression can be called multiple times, so we need to clear the previous preselectResult
preselectResult = null;
if (maxDistance != null) {
max_distance = ((IntegerValue) maxDistance.eval(contextSequence).convertTo(Type.INTEGER)).getInt();
}
if (minDistance != null) {
min_distance = ((IntegerValue) minDistance.eval(contextSequence).convertTo(Type.INTEGER)).getInt();
}
// get the search terms
String arg = searchTerm.eval(contextSequence).getStringValue();
String[] terms;
try {
terms = getSearchTerms(arg);
} catch (EXistException e) {
logger.error(e.getMessage());
throw new XPathException(this, e.getMessage(), e);
}
// lookup the terms in the fulltext index. returns one node set for each term
NodeSet[] hits = getMatches(contextSequence.getDocumentSet(), useContext ? contextSequence.toNodeSet() : null,
NodeSet.DESCENDANT, contextQName, terms);
// walk through the matches and compute the combined node set
preselectResult = hits[0];
if (preselectResult != null) {
for(int k = 1; k < hits.length; k++) {
if(hits[k] != null) {
preselectResult = preselectResult.deepIntersection(hits[k]);
}
}
} else {
preselectResult = NodeSet.EMPTY_SET;
}
if (terms.length > 1) {
boolean hasWildcards = false;
for (int i = 0; i < terms.length; i++) {
hasWildcards |= NativeTextEngine.containsWildcards(terms[i]);
}
preselectResult = (NodeSet) (hasWildcards ? patternMatch(context, terms, preselectResult) :
exactMatch(context, terms, preselectResult));
}
if (context.getProfiler().traceFunctions())
context.getProfiler().traceIndexUsage(context, FTIndex.ID, this,
PerformanceStats.OPTIMIZED_INDEX, System.currentTimeMillis() - start);
return preselectResult;
}
public Sequence evalQuery(String searchArg, NodeSet nodes)
throws XPathException {
// Can return NPE
TextSearchEngine engine = context.getBroker().getTextEngine();
if(engine==null){
throw new XPathException("The legacy fulltext indexing has been disabled by "
+ "default from version 1.4.1. Please consider migrating to "
+ "the new full text indexing..");
}
if (maxDistance != null) {
max_distance = ((IntegerValue) maxDistance.eval(nodes).convertTo(Type.INTEGER)).getInt();
}
if (minDistance != null) {
min_distance = ((IntegerValue) minDistance.eval(nodes).convertTo(Type.INTEGER)).getInt();
}
String[] terms;
try {
terms = getSearchTerms(searchArg);
} catch (EXistException e) {
logger.error(e.getMessage());
throw new XPathException(this, e.getMessage(), e);
}
NodeSet hits = processQuery(terms, nodes);
if (hits == null)
return Sequence.EMPTY_SEQUENCE;
if (terms.length == 1)
return hits;
boolean hasWildcards = false;
for (int i = 0; i < terms.length; i++) {
hasWildcards |= NativeTextEngine.containsWildcards(terms[i]);
}
return hasWildcards ? patternMatch(context, terms, hits) : exactMatch(context, terms, hits);
}
private Sequence exactMatch(XQueryContext context, String[] terms, NodeSet result) {
// walk through hits and calculate term-distances
NodeSet r = new ExtArrayNodeSet();
final Tokenizer tok = context.getBroker().getTextEngine().getTokenizer();
String term;
for (Iterator i = result.iterator(); i.hasNext();) {
NodeProxy current = (NodeProxy) i.next();
String value = current.getNodeValueSeparated();
tok.setText(value);
int j = 0;
if (j < terms.length) {
term = terms[j];
} else {
break;
}
int current_distance = -1;
TextToken token;
while ((token = tok.nextToken()) != null) {
String word = token.getText().toLowerCase();
if (current_distance > max_distance) {
// reset
j = 0;
term = terms[j];
current_distance = -1;
} // that else would cause some words to be ignored in the
// matching
if (word.equalsIgnoreCase(term)) {
boolean withIn = current_distance >= min_distance;
current_distance = 0;
j++;
if (j == terms.length) {
// all terms found
if (withIn) {
r.add(current);
}
break;
} else {
term = terms[j];
}
} else if (j > 0 && word.equalsIgnoreCase(terms[0])) {
// first search term found: start again
j = 1;
term = terms[j];
current_distance = 0;
continue;
} // that else MAY cause the distance counts to be off by one
// but i'm not sure
if (-1 < current_distance) {
++current_distance;
}
}
}
// LOG.debug("found " + r.getLength());
return r;
}
private Sequence patternMatch(XQueryContext context, String[] terms, NodeSet result) {
// generate list of search term patterns
Pattern patterns[] = new Pattern[terms.length];
Matcher matchers[] = new Matcher[terms.length];
for (int i = 0; i < patterns.length; i++) {
try {
patterns[i] = Pattern.compile(GlobToRegex.globToRegexp(terms[i]),
Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE);
matchers[i] = patterns[i].matcher("");
} catch (PatternSyntaxException e) {
logger.error("malformed pattern" + e.getMessage());
return Sequence.EMPTY_SEQUENCE;
}
}
// walk through hits and calculate term-distances
ExtArrayNodeSet r = new ExtArrayNodeSet(100);
Tokenizer tok = context.getBroker().getTextEngine().getTokenizer();
Matcher matcher;
TextToken token;
for (Iterator i = result.iterator(); i.hasNext();) {
NodeProxy current = (NodeProxy) i.next();
String value = current.getNodeValueSeparated();
tok.setText(value);
int j = 0;
if (j < patterns.length) {
//Pattern term = patterns[j];
matcher = matchers[j];
} else {
break;
}
int current_distance = -1;
while ((token = tok.nextToken()) != null) {
String word = token.getText().toLowerCase();
if (current_distance > max_distance) {
// reset
j = 0;
//Pattern term = patterns[j];
matcher = matchers[j];
current_distance = -1;
}
matcher.reset(word);
matchers[0].reset(word);
if (matcher.matches()) {
boolean withIn = current_distance >= min_distance ? true
: false;
current_distance = 0;
j++;
if (j == patterns.length) {
// all terms found
if (withIn) {
r.add(current);
}
break;
} else {
//Pattern term = patterns[j];
matcher = matchers[j];
}
} else if (j > 0 && matchers[0].matches()) {
// first search term found: start again
j = 1;
//Pattern term = patterns[j];
matcher = matchers[j];
current_distance = 0;
continue;
}
if (-1 < current_distance) {
++current_distance;
}
}
}
return r;
}
/*
* (non-Javadoc)
*
* @see org.exist.xquery.functions.ExtFulltext#dump(org.exist.xquery.util.ExpressionDumper)
*/
public void dump(ExpressionDumper dumper) {
dumper.display("near(");
path.dump(dumper);
dumper.display(", ");
searchTerm.dump(dumper);
dumper.display(")");
}
public String toString() {
StringBuilder buf = new StringBuilder();
buf.append("near(");
buf.append(path);
buf.append(", ");
buf.append(searchTerm);
buf.append(")");
return buf.toString();
}
public void setMaxDistance(Expression expr) {
maxDistance = expr;
}
public void setMinDistance(Expression expr) {
minDistance = expr;
}
}