alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

What this is

This file is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Other links

The source code

/*
 * Copyright 1999-2004 The Apache Software Foundation
 *
 * Licensed 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.JXPathException;
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: 1.8 $ $Date: 2004/02/29 14:17:45 $
 */
public class Parser {

    private static XPathParser parser = new XPathParser(new StringReader(""));

    /**
     * Parses the XPath expression. Throws a JXPathException in case
     * of a syntax error.
     */
    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 JXPathException(
                    "Invalid XPath: '"
                        + addEscapes(expression)
                        + "'. Invalid symbol '"
                        + addEscapes(String.valueOf(e.getCharacter()))
                        + "' "
                        + describePosition(expression, e.getPosition()));
            }
            catch (ParseException e) {
                throw new JXPathException(
                    "Invalid XPath: '"
                        + addEscapes(expression)
                        + "'. Syntax error "
                        + describePosition(
                            expression,
                            e.currentToken.beginColumn));
            }
            return expr;
        }
    }

    private static String describePosition(String expression, int position) {
        if (position <= 0) {
            return "at the beginning of the expression";
        }
        else if (position >= expression.length()) {
            return "- expression incomplete";
        }
        else {
            return "after: '"
                + addEscapes(expression.substring(0, position)) + "'";
        }
    }

    private static String addEscapes(String string) {
        // Piggy-back on the code generated by JavaCC
        return TokenMgrError.addEscapes(string);
    }
}
... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.