/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * 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 com.sun.org.apache.xerces.internal.dom;

import org.w3c.dom.DocumentFragment;

import org.w3c.dom.Node;

import org.w3c.dom.Text;

/**

 * DocumentFragment is a "lightweight" or "minimal" Document

 * object. It is very common to want to be able to extract a portion

 * of a document's tree or to create a new fragment of a

 * document. Imagine implementing a user command like cut or

 * rearranging a document by moving fragments around. It is desirable

 * to have an object which can hold such fragments and it is quite

 * natural to use a Node for this purpose. While it is true that a

 * Document object could fulfil this role, a Document object can

 * potentially be a heavyweight object, depending on the underlying

 * implementation... and in DOM Level 1, nodes aren't allowed to cross

 * Document boundaries anyway. What is really needed for this is a

 * very lightweight object.  DocumentFragment is such an object.

 * <P>

 * Furthermore, various operations -- such as inserting nodes as

 * children of another Node -- may take DocumentFragment objects as

 * arguments; this results in all the child nodes of the

 * DocumentFragment being moved to the child list of this node.

 * <P>

 * The children of a DocumentFragment node are zero or more nodes

 * representing the tops of any sub-trees defining the structure of

 * the document.  DocumentFragment do not need to be well-formed XML

 * documents (although they do need to follow the rules imposed upon

 * well-formed XML parsed entities, which can have multiple top

 * nodes). For example, a DocumentFragment might have only one child

 * and that child node could be a Text node. Such a structure model

 * represents neither an HTML document nor a well-formed XML document.

 * <P>

 * When a DocumentFragment is inserted into a Document (or indeed any

 * other Node that may take children) the children of the

 * DocumentFragment and not the DocumentFragment itself are inserted

 * into the Node. This makes the DocumentFragment very useful when the

 * user wishes to create nodes that are siblings; the DocumentFragment

 * acts as the parent of these nodes so that the user can use the

 * standard methods from the Node interface, such as insertBefore()

 * and appendChild().

 *

 * @xerces.internal

 *

 * @since  PR-DOM-Level-1-19980818.

 */

public class DocumentFragmentImpl

    extends ParentNode

    implements DocumentFragment {

    //

    // Constants

    //

    /** Serialization version. */

    static final long serialVersionUID = -7596449967279236746L;

    //

    // Constructors

    //

    /** Factory constructor. */

    public DocumentFragmentImpl(CoreDocumentImpl ownerDoc) {

        super(ownerDoc);

    }

    /** Constructor for serialization. */

    public DocumentFragmentImpl() {}

    //

    // Node methods

    //

    /**

     * A short integer indicating what type of node this is. The named

     * constants for this value are defined in the org.w3c.dom.Node interface.

     */

    public short getNodeType() {

        return Node.DOCUMENT_FRAGMENT_NODE;

    }

    /** Returns the node name. */

    public String getNodeName() {

        return "#document-fragment";

    }

    /**

     * Override default behavior to call normalize() on this Node's

     * children. It is up to implementors or Node to override normalize()

     * to take action.

     */

    public void normalize() {

        // No need to normalize if already normalized.

        if (isNormalized()) {

            return;

        }

        if (needsSyncChildren()) {

            synchronizeChildren();

        }

        ChildNode kid, next;

        for (kid = firstChild; kid != null; kid = next) {

            next = kid.nextSibling;

            // If kid is a text node, we need to check for one of two

            // conditions:

            //   1) There is an adjacent text node

            //   2) There is no adjacent text node, but kid is

            //      an empty text node.

            if ( kid.getNodeType() == Node.TEXT_NODE )

            {

                // If an adjacent text node, merge it with kid

                if ( next!=null && next.getNodeType() == Node.TEXT_NODE )

                {

                    ((Text)kid).appendData(next.getNodeValue());

                    removeChild( next );

                    next = kid; // Don't advance; there might be another.

                }

                else

                {

                    // If kid is empty, remove it

                    if ( kid.getNodeValue() == null || kid.getNodeValue().length() == 0 ) {

                        removeChild( kid );

                    }

                }

            }

            kid.normalize();

        }

        isNormalized(true);

    }

} // class DocumentFragmentImpl