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Java > Open Source Codes > org > apache > taglibs > standard > lang > jpath > expression > ScopeLimitOperator


1 /*
2  * Copyright 1999,2004 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16
17 package org.apache.taglibs.standard.lang.jpath.expression;
18
19 import javax.servlet.jsp.PageContext JavaDoc;
20
21 import org.apache.taglibs.standard.lang.jpath.adapter.ConversionException;
22 import org.apache.taglibs.standard.lang.jpath.adapter.Convert;
23 import org.apache.taglibs.standard.lang.jpath.adapter.IterationContext;
24
25 /**
26  * The ScopeLimitOperator class
27  *
28  *
29  * @author <a HREF='mailto:scott.hasse@isthmusgroup.com'>Scott Hasse</a>
30  * @version
31  */
32 public class ScopeLimitOperator extends SimpleNode {
33
34     /**
35      * Used to create an instance of the ScopeLimitOperator class
36      *
37      *
38      * @param id
39      *
40      */
41     public ScopeLimitOperator(int id) {
42         super(id);
43     }
44
45     /**
46      * Used to create an instance of the ScopeLimitOperator class
47      *
48      *
49      * @param p
50      * @param id
51      *
52      */
53     public ScopeLimitOperator(Parser p, int id) {
54         super(p, id);
55     }
56
57     /**
58      * Provides a method to print a normalized version of the original
59      * expression. The normalized version has standardized spacing and
60      * parenthesis, and can be used to compare expressions formatted
61      * in different ways to see if they are actually the same expression.
62      *
63      *
64      * @return The normalized version of the original expression
65      *
66      */
67     public String JavaDoc toNormalizedString() {
68
69         String JavaDoc normalized = "";
70
71         normalized = jjtGetChild(0).toNormalizedString()
72                 + jjtGetChild(1).toNormalizedString();
73
74         return normalized;
75     }
76
77     /**
78      * This method evaluates this node of the expression and all child nodes.
79      * It returns the result of the
80      * evaluation as an <tt>Object</tt>. If any problems are encountered
81      * during the evaluation, an <tt>EvaluationException</tt> is thrown.
82      *
83      *
84      * @param pageContext the current JSP PageContext
85      *
86      * @param icontext the Iteration Context of the expression. If there is
87      * no interation context, this should be null.
88      *
89      * @return the result of the expression evaluation as an object
90      *
91      * @throws EvaluationException if a problem is encountered during the
92      * evaluation
93      */
94     public Object JavaDoc evaluate(PageContext JavaDoc pageContext, IterationContext icontext)
95             throws EvaluationException {
96
97         Object JavaDoc result;
98         boolean properScope = false;
99         int scope;
100
101         try {
102             String JavaDoc scopeLimit =
103                 Convert.toString(jjtGetChild(0).evaluate(pageContext,
104                     icontext));
105
106             //Map scopes to scope constants
107 if (scopeLimit.equals("page:")) {
108                 properScope = true;
109                 scope = PageContext.PAGE_SCOPE;
110             } else if (scopeLimit.equals("request:")) {
111                 properScope = true;
112                 scope = PageContext.REQUEST_SCOPE;
113             } else if (scopeLimit.equals("session:")) {
114                 properScope = true;
115                 scope = PageContext.SESSION_SCOPE;
116             } else if (scopeLimit.equals("application:")) {
117                 properScope = true;
118                 scope = PageContext.APPLICATION_SCOPE;
119             } else {
120                 throw new EvaluationException("invalid scope operator ["
121                         + scopeLimit + "]");
122             }
123
124             if (properScope) {
125                 result =
126                     ((Introspectable) jjtGetChild(1)).evaluate(pageContext,
127                         icontext, scope);
128             } else {
129                 throw new EvaluationException("invalid scope operator ["
130                         + scopeLimit + "]");
131             }
132         } catch (ConversionException ce) {
133             throw new EvaluationException(this, ce.getMessage());
134         }
135
136         return result;
137     }
138 }
139
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