/*
* Copyright 2010 Yahoo, Inc. All rights reserved.
*
* Licensed 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 com.opensymphony.xwork2.util;
import java.util.regex.Pattern;
/**
* Helper class to convert wildcard expression to regular expression
*/
public class WildcardUtil {
/**
* Convert wildcard pattern to Pattern
* @param pattern String containing wildcard pattern
* @return compiled regular expression as a Pattern
*/
public static Pattern compileWildcardPattern(String pattern) {
StringBuilder buf = new StringBuilder(pattern);
for (int i=buf.length()-1; i>=0; i--)
{
char c = buf.charAt(i);
if (c == '*' && (i == 0 || buf.charAt(i-1) != '\\'))
{
buf.insert(i+1, '?');
buf.insert(i, '.');
}
else if (c == '*')
{
i--; // skip backslash, too
}
else if (needsBackslashToBeLiteralInRegex(c))
{
buf.insert(i, '\\');
}
}
return Pattern.compile(buf.toString());
}
/**
* @param c character to test
* @return true if the given character must be escaped to be a literal
* inside a regular expression.
*/
private static final String theSpecialRegexCharList = ".[]\\?*+{}|()^$";
public static boolean needsBackslashToBeLiteralInRegex(
char c)
{
return (theSpecialRegexCharList.indexOf(c) >= 0);
}
}