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1 /*
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22  * Apache Software Foundation (http://www.apache.org/)."
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55
56 package org.apache.commons.el;
57
58 /**
59  *
60  * <p>An expression representing a String literal value.
61  *
62  * @author Nathan Abramson - Art Technology Group
63  * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: luehe $
64  **/
65
66 public class StringLiteral
67   extends Literal
68 {
69   //-------------------------------------
70 /**
71    *
72    * Constructor
73    **/
74   StringLiteral (Object JavaDoc pValue)
75   {
76     super (pValue);
77   }
78
79   //-------------------------------------
80 /**
81    *
82    * Returns a StringLiteral parsed from the given token (enclosed by
83    * single or double quotes)
84    **/
85   public static StringLiteral fromToken (String JavaDoc pToken)
86   {
87     return new StringLiteral (getValueFromToken (pToken));
88   }
89
90   //-------------------------------------
91 /**
92    *
93    * Returns a StringLiteral with the given string value
94    **/
95   public static StringLiteral fromLiteralValue (String JavaDoc pValue)
96   {
97     return new StringLiteral (pValue);
98   }
99
100   //-------------------------------------
101 /**
102    *
103    * Parses the given token into the literal value
104    **/
105   public static String JavaDoc getValueFromToken (String JavaDoc pToken)
106   {
107     StringBuffer JavaDoc buf = new StringBuffer JavaDoc ();
108     int len = pToken.length () - 1;
109     boolean escaping = false;
110     for (int i = 1; i < len; i++) {
111       char ch = pToken.charAt (i);
112       if (escaping) {
113     buf.append (ch);
114     escaping = false;
115       }
116       else if (ch == '\\') {
117     escaping = true;
118       }
119       else {
120     buf.append (ch);
121       }
122     }
123     return buf.toString ();
124   }
125
126   //-------------------------------------
127 /**
128    *
129    * Converts the specified value to a String token, using " as the
130    * enclosing quotes and escaping any characters that need escaping.
131    **/
132   public static String JavaDoc toStringToken (String JavaDoc pValue)
133   {
134     // See if any escaping is needed
135 if (pValue.indexOf ('\"') < 0 &&
136     pValue.indexOf ('\\') < 0) {
137       return "\"" + pValue + "\"";
138     }
139
140     // Escaping is needed
141 else {
142       StringBuffer JavaDoc buf = new StringBuffer JavaDoc ();
143       buf.append ('\"');
144       int len = pValue.length ();
145       for (int i = 0; i < len; i++) {
146     char ch = pValue.charAt (i);
147     if (ch == '\\') {
148       buf.append ('\\');
149       buf.append ('\\');
150     }
151     else if (ch == '\"') {
152       buf.append ('\\');
153       buf.append ('\"');
154     }
155     else {
156       buf.append (ch);
157     }
158       }
159       buf.append ('\"');
160       return buf.toString ();
161     }
162   }
163
164   //-------------------------------------
165 /**
166    *
167    * Converts the specified value to an identifier token, escaping it
168    * as a string literal if necessary.
169    **/
170   public static String JavaDoc toIdentifierToken (String JavaDoc pValue)
171   {
172     // See if it's a valid java identifier
173 if (isJavaIdentifier (pValue)) {
174       return pValue;
175     }
176
177     // Return as a String literal
178 else {
179       return toStringToken (pValue);
180     }
181   }
182
183   //-------------------------------------
184 /**
185    *
186    * Returns true if the specified value is a legal java identifier
187    **/
188   static boolean isJavaIdentifier (String JavaDoc pValue)
189   {
190     int len = pValue.length ();
191     if (len == 0) {
192       return false;
193     }
194     else {
195       if (!Character.isJavaIdentifierStart (pValue.charAt (0))) {
196     return false;
197       }
198       else {
199     for (int i = 1; i < len; i++) {
200       if (!Character.isJavaIdentifierPart (pValue.charAt (i))) {
201         return false;
202       }
203     }
204     return true;
205       }
206     }
207   }
208
209   //-------------------------------------
210 // Expression methods
211 //-------------------------------------
212 /**
213    *
214    * Returns the expression in the expression language syntax
215    **/
216   public String JavaDoc getExpressionString ()
217   {
218     return toStringToken ((String JavaDoc) getValue ());
219   }
220
221   //-------------------------------------
222 }
223
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