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1   /*
2    * reserved comment block
3    * DO NOT REMOVE OR ALTER!
4    */
5   /*
6    * Copyright 1999-2004 The Apache Software Foundation.
7    *
8    * Licensed under the Apache License, Version 2.0 (the "License");
9    * you may not use this file except in compliance with the License.
10   * You may obtain a copy of the License at
11   *
12   *      http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing, software
15   * distributed under the License is distributed on an "AS IS" BASIS,
16   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17   * See the License for the specific language governing permissions and
18   * limitations under the License.
19   */
20  
21  package com.sun.org.apache.xerces.internal.dom;
22  
23  import org.w3c.dom.DocumentFragment;
24  import org.w3c.dom.Node;
25  import org.w3c.dom.Text;
26  
27  /**
28   * DocumentFragment is a "lightweight" or "minimal" Document
29   * object. It is very common to want to be able to extract a portion
30   * of a document's tree or to create a new fragment of a
31   * document. Imagine implementing a user command like cut or
32   * rearranging a document by moving fragments around. It is desirable
33   * to have an object which can hold such fragments and it is quite
34   * natural to use a Node for this purpose. While it is true that a
35   * Document object could fulfil this role, a Document object can
36   * potentially be a heavyweight object, depending on the underlying
37   * implementation... and in DOM Level 1, nodes aren't allowed to cross
38   * Document boundaries anyway. What is really needed for this is a
39   * very lightweight object.  DocumentFragment is such an object.
40   * <P>
41   * Furthermore, various operations -- such as inserting nodes as
42   * children of another Node -- may take DocumentFragment objects as
43   * arguments; this results in all the child nodes of the
44   * DocumentFragment being moved to the child list of this node.
45   * <P>
46   * The children of a DocumentFragment node are zero or more nodes
47   * representing the tops of any sub-trees defining the structure of
48   * the document.  DocumentFragment do not need to be well-formed XML
49   * documents (although they do need to follow the rules imposed upon
50   * well-formed XML parsed entities, which can have multiple top
51   * nodes). For example, a DocumentFragment might have only one child
52   * and that child node could be a Text node. Such a structure model
53   * represents neither an HTML document nor a well-formed XML document.
54   * <P>
55   * When a DocumentFragment is inserted into a Document (or indeed any
56   * other Node that may take children) the children of the
57   * DocumentFragment and not the DocumentFragment itself are inserted
58   * into the Node. This makes the DocumentFragment very useful when the
59   * user wishes to create nodes that are siblings; the DocumentFragment
60   * acts as the parent of these nodes so that the user can use the
61   * standard methods from the Node interface, such as insertBefore()
62   * and appendChild().
63   *
64   * @xerces.internal
65   *
66   * @since  PR-DOM-Level-1-19980818.
67   */
68  public class DocumentFragmentImpl
69      extends ParentNode
70      implements DocumentFragment {
71  
72      //
73      // Constants
74      //
75  
76      /** Serialization version. */
77      static final long serialVersionUID = -7596449967279236746L;
78  
79      //
80      // Constructors
81      //
82  
83      /** Factory constructor. */
84      public DocumentFragmentImpl(CoreDocumentImpl ownerDoc) {
85          super(ownerDoc);
86      }
87  
88      /** Constructor for serialization. */
89      public DocumentFragmentImpl() {}
90  
91      //
92      // Node methods
93      //
94  
95      /**
96       * A short integer indicating what type of node this is. The named
97       * constants for this value are defined in the org.w3c.dom.Node interface.
98       */
99      public short getNodeType() {
100         return Node.DOCUMENT_FRAGMENT_NODE;
101     }
102 
103     /** Returns the node name. */
104     public String getNodeName() {
105         return "#document-fragment";
106     }
107 
108     /**
109      * Override default behavior to call normalize() on this Node's
110      * children. It is up to implementors or Node to override normalize()
111      * to take action.
112      */
113     public void normalize() {
114         // No need to normalize if already normalized.
115         if (isNormalized()) {
116             return;
117         }
118         if (needsSyncChildren()) {
119             synchronizeChildren();
120         }
121         ChildNode kid, next;
122 
123         for (kid = firstChild; kid != null; kid = next) {
124             next = kid.nextSibling;
125 
126             // If kid is a text node, we need to check for one of two
127             // conditions:
128             //   1) There is an adjacent text node
129             //   2) There is no adjacent text node, but kid is
130             //      an empty text node.
131             if ( kid.getNodeType() == Node.TEXT_NODE )
132             {
133                 // If an adjacent text node, merge it with kid
134                 if ( next!=null && next.getNodeType() == Node.TEXT_NODE )
135                 {
136                     ((Text)kid).appendData(next.getNodeValue());
137                     removeChild( next );
138                     next = kid; // Don't advance; there might be another.
139                 }
140                 else
141                 {
142                     // If kid is empty, remove it
143                     if ( kid.getNodeValue() == null || kid.getNodeValue().length() == 0 ) {
144                         removeChild( kid );
145                     }
146                 }
147             }
148 
149             kid.normalize();
150         }
151 
152         isNormalized(true);
153     }
154 
155 } // class DocumentFragmentImpl