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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: struberg $)
33   * @version $Revision: 1188565 $ $Date: 2011-10-25 08:38:53 +0000 (Tue, 25 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          {
51               // No metadata, so return an empty collection.
52               
53               return Collections.emptyList();
54          }
55          
56          // Iterate over all the children, keep only the view parameters.
57          
58          if (metadataFacet.getChildCount() > 0)
59          {
60              children = metadataFacet.getChildren().iterator();
61              
62              while (children.hasNext())
63              {
64                   UIComponent component = children.next();
65                   
66                   if (result == null)
67                   {
68                       result = new LinkedList<UIViewParameter>();
69                   }
70                   
71                   if (component instanceof UIViewParameter)
72                   {
73                        result.add ((UIViewParameter) component);
74                   }
75              }
76          }
77          
78          // TODO: does this need to be immutable?  Spec does not indicate either
79          // way.
80          if (result == null)
81          {
82              return Collections.emptyList();
83          }
84          else
85          {
86              return Collections.unmodifiableCollection (result);
87          }
88      }
89  }