001: /*
002: * The Apache Software License, Version 1.1
003: *
004: * Copyright (c) 1999 The Apache Software Foundation. All rights
005: * reserved.
006: *
007: * Redistribution and use in source and binary forms, with or without
008: * modification, are permitted provided that the following conditions
009: * are met:
010: *
011: * 1. Redistributions of source code must retain the above copyright
012: * notice, this list of conditions and the following disclaimer.
013: *
014: * 2. Redistributions in binary form must reproduce the above copyright
015: * notice, this list of conditions and the following disclaimer in
016: * the documentation and/or other materials provided with the
017: * distribution.
018: *
019: * 3. The end-user documentation included with the redistribution, if
020: * any, must include the following acknowlegement:
021: * "This product includes software developed by the
022: * Apache Software Foundation (http://www.apache.org/)."
023: * Alternately, this acknowlegement may appear in the software itself,
024: * if and wherever such third-party acknowlegements normally appear.
025: *
026: * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
027: * Foundation" must not be used to endorse or promote products derived
028: * from this software without prior written permission. For written
029: * permission, please contact apache@apache.org.
030: *
031: * 5. Products derived from this software may not be called "Apache"
032: * nor may "Apache" appear in their names without prior written
033: * permission of the Apache Group.
034: *
035: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
036: * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
037: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
038: * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
039: * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
040: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
041: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
042: * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
043: * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
044: * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
045: * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
046: * SUCH DAMAGE.
047: * ====================================================================
048: *
049: * This software consists of voluntary contributions made by many
050: * individuals on behalf of the Apache Software Foundation. For more
051: * information on the Apache Software Foundation, please see
052: * <http://www.apache.org/>.
053: *
054: */
055:
056: package org.apache.commons.el;
057:
058: /**
059: *
060: * <p>An expression representing a String literal value.
061: *
062: * @author Nathan Abramson - Art Technology Group
063: * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: luehe $
064: **/
065:
066: public class StringLiteral extends Literal {
067: //-------------------------------------
068: /**
069: *
070: * Constructor
071: **/
072: StringLiteral(Object pValue) {
073: super (pValue);
074: }
075:
076: //-------------------------------------
077: /**
078: *
079: * Returns a StringLiteral parsed from the given token (enclosed by
080: * single or double quotes)
081: **/
082: public static StringLiteral fromToken(String pToken) {
083: return new StringLiteral(getValueFromToken(pToken));
084: }
085:
086: //-------------------------------------
087: /**
088: *
089: * Returns a StringLiteral with the given string value
090: **/
091: public static StringLiteral fromLiteralValue(String pValue) {
092: return new StringLiteral(pValue);
093: }
094:
095: //-------------------------------------
096: /**
097: *
098: * Parses the given token into the literal value
099: **/
100: public static String getValueFromToken(String pToken) {
101: StringBuffer buf = new StringBuffer();
102: int len = pToken.length() - 1;
103: boolean escaping = false;
104: for (int i = 1; i < len; i++) {
105: char ch = pToken.charAt(i);
106: if (escaping) {
107: buf.append(ch);
108: escaping = false;
109: } else if (ch == '\\') {
110: escaping = true;
111: } else {
112: buf.append(ch);
113: }
114: }
115: return buf.toString();
116: }
117:
118: //-------------------------------------
119: /**
120: *
121: * Converts the specified value to a String token, using " as the
122: * enclosing quotes and escaping any characters that need escaping.
123: **/
124: public static String toStringToken(String pValue) {
125: // See if any escaping is needed
126: if (pValue.indexOf('\"') < 0 && pValue.indexOf('\\') < 0) {
127: return "\"" + pValue + "\"";
128: }
129:
130: // Escaping is needed
131: else {
132: StringBuffer buf = new StringBuffer();
133: buf.append('\"');
134: int len = pValue.length();
135: for (int i = 0; i < len; i++) {
136: char ch = pValue.charAt(i);
137: if (ch == '\\') {
138: buf.append('\\');
139: buf.append('\\');
140: } else if (ch == '\"') {
141: buf.append('\\');
142: buf.append('\"');
143: } else {
144: buf.append(ch);
145: }
146: }
147: buf.append('\"');
148: return buf.toString();
149: }
150: }
151:
152: //-------------------------------------
153: /**
154: *
155: * Converts the specified value to an identifier token, escaping it
156: * as a string literal if necessary.
157: **/
158: public static String toIdentifierToken(String pValue) {
159: // See if it's a valid java identifier
160: if (isJavaIdentifier(pValue)) {
161: return pValue;
162: }
163:
164: // Return as a String literal
165: else {
166: return toStringToken(pValue);
167: }
168: }
169:
170: //-------------------------------------
171: /**
172: *
173: * Returns true if the specified value is a legal java identifier
174: **/
175: static boolean isJavaIdentifier(String pValue) {
176: int len = pValue.length();
177: if (len == 0) {
178: return false;
179: } else {
180: if (!Character.isJavaIdentifierStart(pValue.charAt(0))) {
181: return false;
182: } else {
183: for (int i = 1; i < len; i++) {
184: if (!Character.isJavaIdentifierPart(pValue
185: .charAt(i))) {
186: return false;
187: }
188: }
189: return true;
190: }
191: }
192: }
193:
194: //-------------------------------------
195: // Expression methods
196: //-------------------------------------
197: /**
198: *
199: * Returns the expression in the expression language syntax
200: **/
201: public String getExpressionString() {
202: return toStringToken((String) getValue());
203: }
204:
205: //-------------------------------------
206: }
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