org.danann.cernunnos.xml.NodeProcessor.java Source code

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Here is the source code for org.danann.cernunnos.xml.NodeProcessor.java

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/*
 * Copyright 2007 Andrew Wills
 *
 * 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 org.danann.cernunnos.xml;

import java.util.Iterator;

import org.dom4j.Branch;
import org.dom4j.Element;
import org.dom4j.Namespace;
import org.dom4j.Node;
import org.dom4j.QName;
import org.dom4j.XPath;
import org.dom4j.xpath.DefaultXPath;

import org.danann.cernunnos.Grammar;
import org.danann.cernunnos.Phrase;
import org.danann.cernunnos.TaskRequest;
import org.danann.cernunnos.TaskResponse;

public final class NodeProcessor {
    private final static ThreadLocal<XPath> XPATH_LOCAL = new ThreadLocal<XPath>() {
        /* (non-Javadoc)
         * @see java.lang.ThreadLocal#initialValue()
         */
        @Override
        protected XPath initialValue() {
            return new DefaultXPath("descendant-or-self::text() | descendant-or-self::*/@*");
        }
    };

    /*
     * Public API.
     */

    public static void evaluatePhrases(Node n, Grammar g, TaskRequest req, TaskResponse res) {

        // Assertions...
        if (n == null) {
            String msg = "Argument 'n [Node]' cannot be null.";
            throw new IllegalArgumentException(msg);
        }
        if (g == null) {
            String msg = "Argument 'g [Grammar]' cannot be null.";
            throw new IllegalArgumentException(msg);
        }

        if (n instanceof Branch) {
            ((Branch) n).normalize();
        }

        final XPath xpath = XPATH_LOCAL.get();
        for (Iterator<?> it = xpath.selectNodes(n).iterator(); it.hasNext();) {
            Node d = (Node) it.next();
            if (d.getText().trim().length() != 0) {
                Phrase p = g.newPhrase(d);
                Object o = p.evaluate(req, res);
                String value = o != null ? o.toString() : "null";
                d.setText(value);
            }
        }

    }

    /**
     * Recursively applies the specified <code>Namespace</code> to the specified
     * <code>Element</code>, unless the <code>Element</code> (or any child
     * <code>Element</code>) already specifies a <code>Namespace</code>.
     *
     * @param nsp Namespace to apply.
     * @param e XML structure upon which to apply the Namespace.
     */
    public static void applyNamespace(Namespace nsp, Element e) {

        // Assertions...
        if (nsp == null) {
            String msg = "Argument 'nsp' cannot be null.";
            throw new IllegalArgumentException(msg);
        }
        if (e == null) {
            String msg = "Argument 'e [Element]' cannot be null.";
            throw new IllegalArgumentException(msg);
        }

        if (e.getNamespace().equals(Namespace.NO_NAMESPACE)) {
            e.setQName(new QName(e.getName(), nsp));
            for (Object n : e.elements()) {
                applyNamespace(nsp, (Element) n);
            }
        }

    }

    /*
     * Implementation.
     */

    private NodeProcessor() {
    }

}