/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-09 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
*/
package org.exist.xquery.modules.simpleql;
import java.io.StringReader;
import org.apache.log4j.Logger;
import org.exist.dom.QName;
import org.exist.xquery.BasicFunction;
import org.exist.xquery.Cardinality;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.FunctionReturnSequenceType;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.StringValue;
import org.exist.xquery.value.Type;
import antlr.RecognitionException;
import antlr.TokenStreamException;
public class ParseSimpleQL extends BasicFunction {
private static final Logger logger = Logger.getLogger(ParseSimpleQL.class);
public final static FunctionSignature signature =
new FunctionSignature(
new QName("parse-simpleql", SimpleQLModule.NAMESPACE_URI, SimpleQLModule.PREFIX),
"Translates expressions in a simple query language to an XPath expression. A single search term " +
"is translated into '. &= term', 'and'/'or' used to combine terms, quotes define a phrase and are translated " +
"into near(., 'quoted terms').",
new SequenceType[] { new FunctionParameterSequenceType("expression", Type.STRING, Cardinality.ZERO_OR_ONE, "The expression to parse")},
new FunctionReturnSequenceType(Type.STRING, Cardinality.ZERO_OR_ONE, "the result"));
public ParseSimpleQL(XQueryContext context) {
super(context, signature);
}
public Sequence eval(Sequence[] args, Sequence contextSequence)
throws XPathException {
if (args[0].isEmpty())
return Sequence.EMPTY_SEQUENCE;
String query = args[0].getStringValue();
SimpleQLLexer lexer = new SimpleQLLexer(new StringReader(query));
SimpleQLParser parser = new SimpleQLParser(lexer);
try {
return new StringValue(parser.expr());
} catch (RecognitionException e) {
throw new XPathException(this, "An error occurred while parsing the query expression: " + e.getMessage(), e);
} catch (TokenStreamException e) {
throw new XPathException(this, "An error occurred while parsing the query expression: " + e.getMessage(), e);
}
}
}