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

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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.LinkedList;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.dom4j.Attribute;
import org.dom4j.Branch;
import org.dom4j.Element;
import org.dom4j.Namespace;
import org.dom4j.Node;

import org.danann.cernunnos.AttributePhrase;
import org.danann.cernunnos.Attributes;
import org.danann.cernunnos.EntityConfig;
import org.danann.cernunnos.Formula;
import org.danann.cernunnos.Grammar;
import org.danann.cernunnos.LiteralPhrase;
import org.danann.cernunnos.Phrase;
import org.danann.cernunnos.Reagent;
import org.danann.cernunnos.ReagentType;
import org.danann.cernunnos.SimpleFormula;
import org.danann.cernunnos.SimpleReagent;
import org.danann.cernunnos.Task;
import org.danann.cernunnos.TaskRequest;
import org.danann.cernunnos.TaskResponse;

public final class PrependNodeTask implements Task {

    // Instance Members.
    private Phrase node;
    private Phrase parent;
    private Phrase sibling;
    private List<?> content;
    private Phrase apply_namespace;
    private Grammar grammar;
    private final Log log = LogFactory.getLog(PrependNodeTask.class); // Don't declare as static in general libraries

    /*
     * Public API.
     */

    public static final Reagent NODE = new SimpleReagent("NODE", "@node", ReagentType.PHRASE, Node.class,
            "Optional node that will be prepended.  If not provided, the 'Attributes.NODE' "
                    + "request attribute will be used.",
            new AttributePhrase(Attributes.NODE));

    public static final Reagent PARENT = new SimpleReagent("PARENT", "@parent", ReagentType.PHRASE, Node.class,
            "Optional node under which the specified content will be added at the beginning.  Specify "
                    + "only PARENT or SIBLING, not both.  If neither is specified, the 'Attributes.NODE' "
                    + "request attribute will be used as a PARENT.",
            new AttributePhrase(Attributes.NODE));

    public static final Reagent SIBLING = new SimpleReagent("SIBLING", "@sibling", ReagentType.PHRASE, Node.class,
            "Optional node before which the specified content will be added.  Specify only PARENT or "
                    + "SIBLING, not both.",
            null);

    public static final Reagent CONTENT = new SimpleReagent("CONTENT", "*", ReagentType.NODE_LIST, List.class,
            "Optional XML nodes to prepend.  Use this reagent to specify content in-line.  If "
                    + "CONTENT is present, it will be prefered over NODE.",
            null);

    public static final Reagent APPLY_NAMESPACE = new SimpleReagent("APPLY_NAMESPACE", "@apply-namespace",
            ReagentType.PHRASE, Boolean.class,
            "Tells this task whether to reconstruct the QNames of added elements to include the "
                    + "namespace of the parent element if:  (1) the parent contains a namespace;  and (2) the intended child "
                    + "does not.  The default is Boolean.TRUE.",
            new LiteralPhrase(Boolean.TRUE));

    public Formula getFormula() {
        Reagent[] reagents = new Reagent[] { NODE, PARENT, SIBLING, CONTENT, APPLY_NAMESPACE };
        final Formula rslt = new SimpleFormula(PrependNodeTask.class, reagents);
        return rslt;
    }

    public void init(EntityConfig config) {

        // Instance Members.
        this.node = (Phrase) config.getValue(NODE);
        this.parent = (Phrase) config.getValue(PARENT);
        this.sibling = (Phrase) config.getValue(SIBLING);
        this.content = (List<?>) config.getValue(CONTENT);
        this.apply_namespace = (Phrase) config.getValue(APPLY_NAMESPACE);
        this.grammar = config.getGrammar();

    }

    @SuppressWarnings("unchecked")
    public void perform(TaskRequest req, TaskResponse res) {

        // Figure out where to put the content...
        Branch p = null;
        int index;
        if (sibling != null) {
            Node sib = (Node) sibling.evaluate(req, res);
            p = sib.getParent();
            index = p.indexOf(sib);
        } else {
            // Work from the PARENT...
            p = (Branch) parent.evaluate(req, res);
            index = 0;
        }

        // Figure out what content to add...
        List list = null;
        if (content != null && content.size() > 0) {
            list = content;
        } else {
            list = new LinkedList();
            list.add(node.evaluate(req, res));
        }

        // Evaluate phrases & add...
        for (Object o : list) {

            Node n = (Node) ((Node) o).clone();
            NodeProcessor.evaluatePhrases(n, grammar, req, res);

            // If the parent is an element, check if we should
            // carry the parent namespace over to the child...
            if ((Boolean) apply_namespace.evaluate(req, res) && p.getNodeType() == Node.ELEMENT_NODE
                    && !((Element) p).getNamespace().equals(Namespace.NO_NAMESPACE)) {
                // We know the parent is an Element w/ a namespace,
                // is the child (also) an Element w/ none?
                if (n.getNodeType() == Node.ELEMENT_NODE
                        && ((Element) n).getNamespace().equals(Namespace.NO_NAMESPACE)) {
                    // Yes -- we need to port the namespace forward...
                    Namespace nsp = ((Element) p).getNamespace();
                    if (log.isTraceEnabled()) {
                        StringBuffer msg = new StringBuffer();
                        msg.append("Adding the following namespace to <").append(n.getName()).append(">:  ")
                                .append(nsp);
                        log.trace(msg.toString());
                    }
                    NodeProcessor.applyNamespace(nsp, (Element) n);
                }
            }

            // Although they *are* nodes, attributes are not technically
            // content, and therefore they must have special treatment...
            if (p.getNodeType() == Node.ELEMENT_NODE && n.getNodeType() == Node.ATTRIBUTE_NODE) {
                // Add attributes by calling addAttribute on the Element contract...
                ((Element) p).add((Attribute) n);
            } else {
                // Add everything else as 'content'...
                p.content().add(index++, n);
            }

        }

    }

}