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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *   http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  package javax.faces.view;
20  
21  import java.util.Collection;
22  import java.util.Collections;
23  import java.util.Iterator;
24  import java.util.LinkedList;
25  
26  import javax.faces.component.UIComponent;
27  import javax.faces.component.UIViewParameter;
28  import javax.faces.component.UIViewRoot;
29  import javax.faces.context.FacesContext;
30  
31  /**
32   * @author Simon Lessard (latest modification by $Author: bommel $)
33   * @version $Revision: 1187700 $ $Date: 2011-10-22 12:19:37 +0000 (Sat, 22 Oct 2011) $
34   *
35   * @since 2.0
36   */
37  public abstract class ViewMetadata
38  {
39      public abstract UIViewRoot createMetadataView(FacesContext context);
40      
41      public abstract String getViewId();
42      
43      public static Collection<UIViewParameter> getViewParameters(UIViewRoot root)
44      {
45          LinkedList<UIViewParameter> result = null;
46          UIComponent metadataFacet = root.getFacet (UIViewRoot.METADATA_FACET_NAME);
47          Iterator<UIComponent> children;
48          
49          if (metadataFacet == null) {
50               // No metadata, so return an empty collection.
51               
52               return Collections.emptyList();
53          }
54          
55          // Iterate over all the children, keep only the view parameters.
56          
57          if (metadataFacet.getChildCount() > 0)
58          {
59              children = metadataFacet.getChildren().iterator();
60              
61              while (children.hasNext()) {
62                   UIComponent component = children.next();
63                   
64                   if (result == null)
65                   {
66                       result = new LinkedList<UIViewParameter>();
67                   }
68                   
69                   if (component instanceof UIViewParameter) {
70                        result.add ((UIViewParameter) component);
71                   }
72              }
73          }
74          
75          // TODO: does this need to be immutable?  Spec does not indicate either
76          // way.
77          if (result == null)
78          {
79              return Collections.emptyList();
80          }
81          else
82          {
83              return Collections.unmodifiableCollection (result);
84          }
85      }
86  }