BaseEvaluator


1   /*
2    * Copyright (C) 2005 Alfresco, Inc.
3    *
4    * Licensed under the Mozilla Public License version 1.1 
5    * with a permitted attribution clause. You may obtain a
6    * copy of the License at
7    *
8    *   http://www.alfresco.org/legal/license.txt
9    *
10   * Unless required by applicable law or agreed to in writing,
11   * software distributed under the License is distributed on an
12   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
13   * either express or implied. See the License for the specific
14   * language governing permissions and limitations under the
15   * License.
16   */
17  package org.alfresco.web.ui.common.component.evaluator;
18  
19  import java.io.IOException  ;
20  
21  import javax.faces.context.FacesContext;
22  import javax.faces.el.ValueBinding;
23  
24  import org.apache.log4j.Logger;
25  
26  import org.alfresco.web.ui.common.component.SelfRenderingComponent;
27  
28  /**
29   * @author kevinr
30   */
31  public abstract class BaseEvaluator extends SelfRenderingComponent
32  {
33     /**
34      * @see javax.faces.component.UIComponent#getFamily()
35      */
36     public final String   getFamily()
37     {
38        return "org.alfresco.faces.evaluators";
39     }
40  
41     /**
42      * @see javax.faces.component.UIComponentBase#getRendersChildren()
43      */
44     public final boolean getRendersChildren()
45     {
46        return !evaluate();
47     }
48  
49     /**
50      * @see javax.faces.component.UIComponentBase#encodeBegin(javax.faces.context.FacesContext)
51      */
52     public final void encodeBegin(FacesContext context) throws IOException  
53     {
54        // no output for this component
55     }
56  
57     /**
58      * @see javax.faces.component.UIComponentBase#encodeChildren(javax.faces.context.FacesContext)
59      */
60     public final void encodeChildren(FacesContext context) throws IOException  
61     {
62        // if this is called, then the evaluate returned false which means
63        // the child components show not be allowed to render themselves
64     }
65  
66     /**
67      * @see javax.faces.component.UIComponentBase#encodeEnd(javax.faces.context.FacesContext)
68      */
69     public final void encodeEnd(FacesContext context) throws IOException  
70     {
71        // no output for this component
72     }
73     
74     /**
75      * Get the value for this component to be evaluated against
76      *
77      * @return the value for this component to be evaluated against
78      */
79     public Object   getValue()
80     {
81        ValueBinding vb = getValueBinding("value");
82        if (vb != null)
83        {
84           this.value = vb.getValue(getFacesContext());
85        }
86        
87        return this.value;
88     }
89  
90     /**
91      * Set the value for this component to be evaluated against
92      *
93      * @param value     the value for this component to be evaluated against
94      */
95     public void setValue(Object   value)
96     {
97        this.value = value;
98     }
99     
100    /**
101     * @see javax.faces.component.StateHolder#restoreState(javax.faces.context.FacesContext, java.lang.Object)
102     */
103    public void restoreState(FacesContext context, Object   state)
104    {
105       Object   values[] = (Object  [])state;
106       // standard component attributes are restored by the super class
107       super.restoreState(context, values[0]);
108       this.value = values[1];
109    }
110    
111    /**
112     * @see javax.faces.component.StateHolder#saveState(javax.faces.context.FacesContext)
113     */
114    public Object   saveState(FacesContext context)
115    {
116       Object   values[] = new Object  [2];
117       // standard component attributes are saved by the super class
118       values[0] = super.saveState(context);
119       values[1] = this.value;
120       return (values);
121    }
122    
123    /**
124     * Evaluate against the component attributes. Return true to allow the inner
125     * components to render, false to hide them during rendering.
126     * 
127     * @return true to allow rendering of child components, false otherwise
128     */
129    public abstract boolean evaluate();
130    
131    
132    protected static Logger s_logger = Logger.getLogger(BaseEvaluator.class);
133    
134    /** the value to be evaluated against */
135    private Object   value;
136 }
137
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