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XWork is an command-pattern framework that is used to power WebWork
as well as other applications. XWork provides an Inversion of Control
container, a powerful expression language, data type conversion,
validation, and pluggable configuration.
/*
* Copyright (c) 2002-2006 by OpenSymphony
* All rights reserved.
*/
package com.opensymphony.xwork2.util;
import com.opensymphony.xwork2.util.TextUtils;
import java.util.HashSet;
import java.util.Set;
/**
* Utility class for text parsing.
*
* @author Jason Carreira
* @author Rainer Hermanns
* @author tm_jee
*
* @version $Date: 2007-07-16 09:34:17 -0500 (Mon, 16 Jul 2007) $ $Id: TextParseUtil.java 1544 2007-07-16 14:34:17Z mrdon $
*/
public class TextParseUtil {
private static final int MAX_RECURSION = 1;
/**
* Converts all instances of ${...} in expression to the value returned
* by a call to {@link ValueStack#findValue(java.lang.String)}. If an item cannot
* be found on the stack (null is returned), then the entire variable ${...} is not
* displayed, just as if the item was on the stack but returned an empty string.
*
* @param expression an expression that hasn't yet been translated
* @return the parsed expression
*/
public static String translateVariables(String expression, ValueStack stack) {
return translateVariables('$', expression, stack, String.class, null).toString();
}
/**
* Function similarly as {@link #translateVariables(char, String, ValueStack)}
* except for the introduction of an additional evaluator that allows
* the parsed value to be evaluated by the evaluator. The evaluator
* could be null, if it is it will just be skipped as if it is just calling
* {@link #translateVariables(char, String, ValueStack)}.
*
*
*
* A typical use-case would be when we need to URL Encode the parsed value. To do so
* we could just supply a URLEncodingEvaluator for example.
*
* @param expression
* @param stack
* @param evaluator The parsed Value evaluator (could be null).
* @return the parsed (and possibly evaluated) variable String.
*/
public static String translateVariables(String expression, ValueStack stack, ParsedValueEvaluator evaluator) {
return translateVariables('$', expression, stack, String.class, evaluator).toString();
}
/**
* Converts all instances of ${...} in expression to the value returned
* by a call to {@link ValueStack#findValue(java.lang.String)}. If an item cannot
* be found on the stack (null is returned), then the entire variable ${...} is not
* displayed, just as if the item was on the stack but returned an empty string.
*
* @param open
* @param expression
* @param stack
* @return Translated variable String
*/
public static String translateVariables(char open, String expression, ValueStack stack) {
return translateVariables(open, expression, stack, String.class, null).toString();
}
/**
* Converted object from variable translation.
*
* @param open
* @param expression
* @param stack
* @param asType
* @return Converted object from variable translation.
*/
public static Object translateVariables(char open, String expression, ValueStack stack, Class asType) {
return translateVariables(open, expression, stack, asType, null);
}
/**
* Converted object from variable translation.
*
* @param open
* @param expression
* @param stack
* @param asType
* @param evaluator
* @return Converted object from variable translation.
*/
public static Object translateVariables(char open, String expression, ValueStack stack, Class asType, ParsedValueEvaluator evaluator) {
return translateVariables(open, expression, stack, asType, evaluator, MAX_RECURSION);
}
/**
* Converted object from variable translation.
*
* @param open
* @param expression
* @param stack
* @param asType
* @param evaluator
* @return Converted object from variable translation.
*/
public static Object translateVariables(char open, String expression, ValueStack stack, Class asType, ParsedValueEvaluator evaluator, int maxLoopCount) {
// deal with the "pure" expressions first!
//expression = expression.trim();
Object result = expression;
int loopCount = 1;
int pos = 0;
while (true) {
int start = expression.indexOf(open + "{", pos);
if (start == -1) {
pos = 0;
loopCount++;
start = expression.indexOf(open + "{");
}
if (loopCount > maxLoopCount) {
// translateVariables prevent infinite loop / expression recursive evaluation
break;
}
int length = expression.length();
int x = start + 2;
int end;
char c;
int count = 1;
while (start != -1 && x < length && count != 0) {
c = expression.charAt(x++);
if (c == '{') {
count++;
} else if (c == '}') {
count--;
}
}
end = x - 1;
if ((start != -1) && (end != -1) && (count == 0)) {
String var = expression.substring(start + 2, end);
Object o = stack.findValue(var, asType);
if (evaluator != null) {
o = evaluator.evaluate(o);
}
String left = expression.substring(0, start);
String right = expression.substring(end + 1);
String middle = null;
if (o != null) {
middle = o.toString();
if (!TextUtils.stringSet(left)) {
result = o;
} else {
result = left + middle;
}
if (TextUtils.stringSet(right)) {
result = result + right;
}
expression = left + middle + right;
} else {
// the variable doesn't exist, so don't display anything
result = left + right;
expression = left + right;
}
pos = (left != null && left.length() > 0 ? left.length() - 1: 0) +
(middle != null && middle.length() > 0 ? middle.length() - 1: 0) +
1;
pos = Math.max(pos, 1);
} else {
break;
}
}
return XWorkConverter.getInstance().convertValue(stack.getContext(), result, asType);
}
/**
* Returns a set from comma delimted Strings.
* @param s The String to parse.
* @return A set from comma delimted Strings.
*/
public static Set commaDelimitedStringToSet(String s) {
Set set = new HashSet();
String[] split = s.split(",");
for (int i = 0; i < split.length; i++) {
String trimmed = split[i].trim();
if (trimmed.length() > 0)
set.add(trimmed);
}
return set;
}
/**
* A parsed value evaluator for {@link TextParseUtil}. It could be supplied by
* calling {@link TextParseUtil#translateVariables(char, String, ValueStack, Class, ParsedValueEvaluator)}.
*
*
*
* By supplying this ParsedValueEvaluator, the parsed value
* (parsed against the value stack) value will be
* given to ParsedValueEvaluator to be evaluated before the
* translateVariable process goes on.
*
*
*
* A typical use-case would be to have a custom ParseValueEvaluator
* to URL Encode the parsed value.
*
* @author tm_jee
*
* @version $Date: 2007-07-16 09:34:17 -0500 (Mon, 16 Jul 2007) $ $Id: TextParseUtil.java 1544 2007-07-16 14:34:17Z mrdon $
*/
public static interface ParsedValueEvaluator {
/**
* Evaluated the value parsed by Ognl value stack.
*
* @param parsedValue - value parsed by ognl value stack
* @return return the evaluted value.
*/
Object evaluate(Object parsedValue);
}
}