# TextProcessingEvaluatorFactory.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.source.*;
    import org.apache.synapse.commons.evaluators.EvaluatorConstants;
    import org.apache.synapse.commons.evaluators.EvaluatorException;
    import org.apache.axiom.om.OMElement;
    import org.apache.axiom.om.OMAttribute;
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;

    import javax.xml.namespace.QName;

    public abstract class TextProcessingEvaluatorFactory implements EvaluatorFactory {

        protected Log log = LogFactory.getLog(this.getClass());

        protected SourceTextRetriever getSourceTextRetriever(OMElement e) throws EvaluatorException {
            OMAttribute typeAttr = e.getAttribute(new QName(EvaluatorConstants.TYPE));
            OMAttribute sourceAttr = e.getAttribute(new QName(EvaluatorConstants.SOURCE));

            SourceTextRetriever textRetriever = null;
            if (typeAttr != null) {
                String value = typeAttr.getAttributeValue();
                if (value.equals(EvaluatorConstants.HEADER)) {
                    if (sourceAttr != null) {
                        textRetriever = new HeaderTextRetriever(sourceAttr.getAttributeValue());
                    } else {
                        handleException(EvaluatorConstants.SOURCE + " attribute is required");
                    }
                } else if (value.equals(EvaluatorConstants.PARAM)) {
                    if (sourceAttr != null) {
                        textRetriever = new ParameterTextRetriever(sourceAttr.getAttributeValue());
                    } else {
                        handleException(EvaluatorConstants.SOURCE + " attribute is required");
                    }
                } else if (value.equals(EvaluatorConstants.URL)) {
                    textRetriever = new URLTextRetriever();
                    if (sourceAttr != null) {
                        ((URLTextRetriever) textRetriever).setSource(sourceAttr.getAttributeValue());
                    }
                } else if (value.equals(EvaluatorConstants.PROPERTY)) {
                    if (sourceAttr != null) {
                        textRetriever = new PropertyTextRetriever(sourceAttr.getAttributeValue());
                    } else {
                        handleException(EvaluatorConstants.SOURCE + " attribute is required");
                    }
                } else if (value.equals(EvaluatorConstants.SOAP)) {
                    if (sourceAttr != null) {
                        textRetriever = new SOAPEnvelopeTextRetriever(sourceAttr.getAttributeValue());
                    } else {
                        handleException(EvaluatorConstants.SOURCE + " attribute is required");
                    }
                } else {
                    handleException("Unknown equal evaluator type: " + value);
                }

            } else {
                if (sourceAttr != null) {
                    textRetriever = new HeaderTextRetriever(sourceAttr.getAttributeValue());
                } else {
                    handleException(EvaluatorConstants.SOURCE + " attribute is required");
                }
            }

            return textRetriever;
        }

        protected void handleException(String message) throws EvaluatorException {
            log.error(message);
            throw new EvaluatorException(message);
        }
    }