# MatchFactory.java

    /*
     *  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.synapse.commons.evaluators.config;

    import org.apache.synapse.commons.evaluators.Evaluator;
    import org.apache.synapse.commons.evaluators.EvaluatorException;
    import org.apache.synapse.commons.evaluators.MatchEvaluator;
    import org.apache.synapse.commons.evaluators.EvaluatorConstants;
    import org.apache.synapse.commons.evaluators.source.SourceTextRetriever;
    import org.apache.axiom.om.OMElement;
    import org.apache.axiom.om.OMAttribute;

    import javax.xml.namespace.QName;
    import java.util.regex.Pattern;

    /**
     * This Factory creates a {@link MatchEvaluator} using the following XML configuration.</p>
     *
     * <pre>
     * &lt;match type=&quot;header | param | url&quot; source=&quot;&quot; regex=&quot;&quot;/&gt;
     * </pre>
     */
    public class MatchFactory extends TextProcessingEvaluatorFactory {

        public Evaluator create(OMElement e) throws EvaluatorException {
            MatchEvaluator equal = new MatchEvaluator();
            SourceTextRetriever textRetriever = getSourceTextRetriever(e);
            equal.setTextRetriever(textRetriever);

            OMAttribute regExAttr = e.getAttribute(new QName(EvaluatorConstants.REGEX));
            if (regExAttr == null) {
                handleException(EvaluatorConstants.REGEX + " attribute is required");
                return null;
            }

            equal.setRegex(Pattern.compile(regExAttr.getAttributeValue()));
            return equal;
        }
    }