org.apache.taglibs.standard.lang.jstl.StringLiteral Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.taglibs.standard.lang.jstl;
/**
* An expression representing a String literal value.
*
* @author Nathan Abramson - Art Technology Group
*/
public class StringLiteral
extends Literal {
//-------------------------------------
/**
* Constructor
*/
StringLiteral(Object pValue) {
super(pValue);
}
//-------------------------------------
/**
* Returns a StringLiteral parsed from the given token (enclosed by
* single or double quotes)
*/
public static StringLiteral fromToken(String pToken) {
return new StringLiteral(getValueFromToken(pToken));
}
//-------------------------------------
/**
* Returns a StringLiteral with the given string value
*/
public static StringLiteral fromLiteralValue(String pValue) {
return new StringLiteral(pValue);
}
//-------------------------------------
/**
* Parses the given token into the literal value
*/
public static String getValueFromToken(String pToken) {
StringBuffer buf = new StringBuffer();
int len = pToken.length() - 1;
boolean escaping = false;
for (int i = 1; i < len; i++) {
char ch = pToken.charAt(i);
if (escaping) {
buf.append(ch);
escaping = false;
} else if (ch == '\\') {
escaping = true;
} else {
buf.append(ch);
}
}
return buf.toString();
}
//-------------------------------------
/**
* Converts the specified value to a String token, using " as the
* enclosing quotes and escaping any characters that need escaping.
*/
public static String toStringToken(String pValue) {
// See if any escaping is needed
if (pValue.indexOf('\"') < 0 &&
pValue.indexOf('\\') < 0) {
return "\"" + pValue + "\"";
}
// Escaping is needed
else {
StringBuffer buf = new StringBuffer();
buf.append('\"');
int len = pValue.length();
for (int i = 0; i < len; i++) {
char ch = pValue.charAt(i);
if (ch == '\\') {
buf.append('\\');
buf.append('\\');
} else if (ch == '\"') {
buf.append('\\');
buf.append('\"');
} else {
buf.append(ch);
}
}
buf.append('\"');
return buf.toString();
}
}
//-------------------------------------
/**
* Converts the specified value to an identifier token, escaping it
* as a string literal if necessary.
*/
public static String toIdentifierToken(String pValue) {
// See if it's a valid java identifier
if (isJavaIdentifier(pValue)) {
return pValue;
}
// Return as a String literal
else {
return toStringToken(pValue);
}
}
//-------------------------------------
/**
* Returns true if the specified value is a legal java identifier
*/
static boolean isJavaIdentifier(String pValue) {
int len = pValue.length();
if (len == 0) {
return false;
} else {
if (!Character.isJavaIdentifierStart(pValue.charAt(0))) {
return false;
} else {
for (int i = 1; i < len; i++) {
if (!Character.isJavaIdentifierPart(pValue.charAt(i))) {
return false;
}
}
return true;
}
}
}
//-------------------------------------
// Expression methods
//-------------------------------------
/**
* Returns the expression in the expression language syntax
*/
public String getExpressionString() {
return toStringToken((String) getValue());
}
//-------------------------------------
}