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Java > Open Source Codes > org > apache > commons > el > ExpressionString


1 /*
2  * The Apache Software License, Version 1.1
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4  * Copyright (c) 1999 The Apache Software Foundation. All rights
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17  * distribution.
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20  * any, must include the following acknowlegement:
21  * "This product includes software developed by the
22  * Apache Software Foundation (http://www.apache.org/)."
23  * Alternately, this acknowlegement may appear in the software itself,
24  * if and wherever such third-party acknowlegements normally appear.
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55
56 package org.apache.commons.el;
57
58 import javax.servlet.jsp.el.ELException JavaDoc;
59 import javax.servlet.jsp.el.VariableResolver JavaDoc;
60 import javax.servlet.jsp.el.FunctionMapper JavaDoc;
61
62 /**
63  *
64  * <p>Represents an expression String consisting of a mixture of
65  * Strings and Expressions.
66  *
67  * @author Nathan Abramson - Art Technology Group
68  * @author Shawn Bayern
69  * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: luehe $
70  **/
71
72 public class ExpressionString
73 {
74   //-------------------------------------
75 // Properties
76 //-------------------------------------
77 // property elements
78
79   Object JavaDoc [] mElements;
80   public Object JavaDoc [] getElements ()
81   { return mElements; }
82   public void setElements (Object JavaDoc [] pElements)
83   { mElements = pElements; }
84
85   //-------------------------------------
86 /**
87    *
88    * Constructor
89    **/
90   public ExpressionString (Object JavaDoc [] pElements)
91   {
92     mElements = pElements;
93   }
94
95   //-------------------------------------
96 /**
97    *
98    * Evaluates the expression string by evaluating each element,
99    * converting it to a String (using toString, or "" for null values)
100    * and concatenating the results into a single String.
101    **/
102   public String JavaDoc evaluate (VariableResolver JavaDoc pResolver,
103               FunctionMapper JavaDoc functions,
104               Logger pLogger)
105     throws ELException JavaDoc
106   {
107     StringBuffer JavaDoc buf = new StringBuffer JavaDoc ();
108     for (int i = 0; i < mElements.length; i++) {
109       Object JavaDoc elem = mElements [i];
110       if (elem instanceof String JavaDoc) {
111     buf.append ((String JavaDoc) elem);
112       }
113       else if (elem instanceof Expression) {
114     Object JavaDoc val =
115       ((Expression) elem).evaluate (pResolver,
116                     functions,
117                     pLogger);
118     if (val != null) {
119       buf.append (val.toString ());
120     }
121       }
122     }
123     return buf.toString ();
124   }
125
126   //-------------------------------------
127 /**
128    *
129    * Returns the expression in the expression language syntax
130    **/
131   public String JavaDoc getExpressionString ()
132   {
133     StringBuffer JavaDoc buf = new StringBuffer JavaDoc ();
134     for (int i = 0; i < mElements.length; i++) {
135       Object JavaDoc elem = mElements [i];
136       if (elem instanceof String JavaDoc) {
137     buf.append ((String JavaDoc) elem);
138       }
139       else if (elem instanceof Expression) {
140     buf.append ("${");
141     buf.append (((Expression) elem).getExpressionString ());
142     buf.append ("}");
143       }
144     }
145     return buf.toString ();
146   }
147
148   //-------------------------------------
149 }
150
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