FileDocCategorySizeDatePackage
DocumentFragmentImpl.javaAPI DocApache Xerces 3.0.15799Fri Sep 14 20:33:56 BST 2007org.apache.xerces.dom

DocumentFragmentImpl

public class DocumentFragmentImpl extends ParentNode implements DocumentFragment
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.

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.

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.

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
version
$Id: DocumentFragmentImpl.java 447266 2006-09-18 05:57:49Z mrglavas $
since
PR-DOM-Level-1-19980818.

Fields Summary
static final long
serialVersionUID
Serialization version.
Constructors Summary
public DocumentFragmentImpl(CoreDocumentImpl ownerDoc)
Factory constructor.

    
    //
    // Constructors
    //

       
       
        super(ownerDoc);
public DocumentFragmentImpl()
Constructor for serialization.

Methods Summary
public java.lang.StringgetNodeName()
Returns the node name.
        return "#document-fragment";
    
public shortgetNodeType()
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.
        return Node.DOCUMENT_FRAGMENT_NODE;
    
public voidnormalize()
Override default behavior to call normalize() on this Node's
children. It is up to implementors or Node to override normalize()
to take action.
        // 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);