com.pavelvlasov.uml.eval.JXPathEvaluator.java Source code

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Here is the source code for com.pavelvlasov.uml.eval.JXPathEvaluator.java

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/*
 * umlapi 1.1.2
 * UML API 
 * Copyright (C) 2003  Pavel Vlasov
 *
 * 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 library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * URL: http://www.pavelvlasov.com/Products/UmlApi/index.html
 * e-Mail: vlasov@pavelvlasov.com
    
 */
package com.pavelvlasov.uml.eval;

import org.apache.commons.jxpath.JXPathContext;

import com.pavelvlasov.uml.Element;

/**
 * @author Pavel Vlasov   
 * @version $Revision$
 */
public class JXPathEvaluator implements Evaluator {
    private JXPathParentContextResolver parentContextResolver;

    public String evaluate(String expr, Object contextObject) {
        Object res = null;
        if (contextObject instanceof Element) {
            res = ((Element) contextObject).navigate(expr);
        } else {
            JXPathContext parentContext = parentContextResolver == null ? null
                    : parentContextResolver.resolveParentContext(contextObject);

            /*
             * Don't cache results if parent context resolver is not null
             */
            if (parentContextResolver != null) {
                CachingInvocationHandler.doNotCacheCurrentResult();
            }

            JXPathContext context = parentContext == null ? JXPathContext.newContext(contextObject)
                    : JXPathContext.newContext(parentContext, contextObject);
            res = context.getValue(expr);
        }
        return res == null ? "" : res.toString();
    }

    /**
     * @param parentContextResolver
     */
    public JXPathEvaluator(JXPathParentContextResolver parentContextResolver) {
        super();
        this.parentContextResolver = parentContextResolver;
    }
}