/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.jxpath.ri;
import java.io.StringReader;
import org.apache.commons.jxpath.JXPathInvalidSyntaxException;
import org.apache.commons.jxpath.ri.parser.ParseException;
import org.apache.commons.jxpath.ri.parser.TokenMgrError;
import org.apache.commons.jxpath.ri.parser.XPathParser;
/**
* XPath parser
*
* @author Dmitri Plotnikov
* @version $Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
*/
public class Parser {
private static XPathParser parser = new XPathParser(new StringReader(""));
/**
* Parses the XPath expression. Throws a JXPathException in case
* of a syntax error.
* @param expression to parse
* @param compiler the compiler
* @return parsed Object
*/
public static Object parseExpression(
String expression,
Compiler compiler) {
synchronized (parser) {
parser.setCompiler(compiler);
Object expr = null;
try {
parser.ReInit(new StringReader(expression));
expr = parser.parseExpression();
}
catch (TokenMgrError e) {
throw new JXPathInvalidSyntaxException(
"Invalid XPath: '"
+ addEscapes(expression)
+ "'. Invalid symbol '"
+ addEscapes(String.valueOf(e.getCharacter()))
+ "' "
+ describePosition(expression, e.getPosition()));
}
catch (ParseException e) {
throw new JXPathInvalidSyntaxException(
"Invalid XPath: '"
+ addEscapes(expression)
+ "'. Syntax error "
+ describePosition(
expression,
e.currentToken.beginColumn));
}
return expr;
}
}
/**
* Describe a parse position.
* @param expression to parse
* @param position parse position
* @return String
*/
private static String describePosition(String expression, int position) {
if (position <= 0) {
return "at the beginning of the expression";
}
if (position >= expression.length()) {
return "- expression incomplete";
}
return "after: '"
+ addEscapes(expression.substring(0, position)) + "'";
}
/**
* Add escapes to the specified String.
* @param string incoming String
* @return String
*/
private static String addEscapes(String string) {
// Piggy-back on the code generated by JavaCC
return TokenMgrError.addEscapes(string);
}
}