net.sf.taverna.t2.activities.xpath.XPathUtils.java Source code

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Here is the source code for net.sf.taverna.t2.activities.xpath.XPathUtils.java

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/*******************************************************************************
 * Copyright (C) 2013 The University of Manchester
 *
 *  Modifications to the initial code base are copyright of their
 *  respective authors, or their employers as appropriate.
 *
 *  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 2.1 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 ******************************************************************************/
package net.sf.taverna.t2.activities.xpath;

import static org.dom4j.DocumentHelper.createXPath;

import org.dom4j.DocumentHelper;
import org.dom4j.InvalidXPathException;

import com.fasterxml.jackson.databind.JsonNode;

/**
 * Utility methods for validating xpath expressions.
 * 
 * @author David Withers
 */
public class XPathUtils {

    public static final int XPATH_VALID = 1;
    public static final int XPATH_EMPTY = 0;
    public static final int XPATH_INVALID = -1;

    /**
     * Validates an XPath expression.
     * 
     * @return {@link XPathActivityConfigurationBean#XPATH_VALID XPATH_VALID} -
     *         if the expression is valid;<br/>
     *         {@link XPathActivityConfigurationBean#XPATH_EMPTY XPATH_EMPTY} -
     *         if expression is empty;<br/>
     *         {@link XPathActivityConfigurationBean#XPATH_INVALID
     *         XPATH_INVALID} - if the expression is invalid / ill-formed.<br/>
     */
    public static int validateXPath(String xpathExpressionToValidate) {
        // no XPath expression
        if (xpathExpressionToValidate == null || xpathExpressionToValidate.trim().isEmpty()) {
            return XPATH_EMPTY;
        }

        try {
            // try to parse the XPath expression...
            createXPath(xpathExpressionToValidate.trim());
            // ...success
            return XPATH_VALID;
        } catch (InvalidXPathException e) {
            // ...failed to parse the XPath expression: notify of the error
            return XPATH_INVALID;
        }
    }

    /**
     * Tests validity of the configuration held.
     * 
     * @return <code>true</code> if the configuration in the bean is valid;
     *         <code>false</code> otherwise.
     */
    public static boolean isValid(JsonNode json) {
        return (json.has("xpathExpression") && validateXPath(json.get("xpathExpression").textValue()) == XPATH_VALID
                && json.has("xpathNamespaceMap"));
    }
}