com.discursive.jccook.collections.predicate.XPathPredicate.java Source code

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Here is the source code for com.discursive.jccook.collections.predicate.XPathPredicate.java

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/* 
 * ========================================================================
 * 
 * Copyright 2005 Tim O'Brien.
 *
 * 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 com.discursive.jccook.collections.predicate;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.apache.commons.collections.Predicate;
import org.apache.commons.collections.map.TypedMap;
import org.apache.commons.jxpath.JXPathContext;
import org.apache.commons.jxpath.JXPathException;

public class XPathPredicate implements Predicate {

    private String path;
    private Map variables = TypedMap.decorate(new HashMap(), String.class, Object.class);

    public XPathPredicate(String path) {
        this.path = path;
    }

    public XPathPredicate(String path, Map variables) {
        this.path = path;
        this.variables.putAll(variables);
    }

    public boolean evaluate(Object object) {
        boolean matches = false;
        JXPathContext context = JXPathContext.newContext(object);
        if (variables != null) {
            populateVariables(context);
        }
        try {
            Object value = context.getValue(path);
            if (value != null) {
                matches = true;
            }
        } catch (JXPathException e) {
            // If this happens there is no match
        }
        return matches;
    }

    private void populateVariables(JXPathContext context) {
        Set keys = variables.keySet();
        Iterator keyIter = keys.iterator();
        while (keyIter.hasNext()) {
            String key = (String) keyIter.next();
            context.getVariables().declareVariable(key, variables.get(key));
        }
    }

}