org.apache.taglibs.standard.lang.jstl.StringLiteral Maven / Gradle / Ivy
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package org.apache.taglibs.standard.lang.jstl;
/**
*
* An expression representing a String literal value.
*
* @author Nathan Abramson - Art Technology Group
* @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: kchung $
**/
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 ());
}
//-------------------------------------
}