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Core classes for Swiss Java Knife tool
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/**
 * Copyright 2013 Alexey Ragozin
 *
 * 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 org.gridkit.jvmtool;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * @author Alexey Ragozin ([email protected])
 */
public class GlobHelper {
	
	/**
	 * GLOB pattern supports *, ** and ? wild cards.
	 * Leading and trailing ** have special meaning, consecutive separator become optional. 
	 */
	public static Pattern translate(String pattern, String separator) {
		StringBuffer sb = new StringBuffer();
		String es = escape(separator);
		// special starter
		Matcher ss = Pattern.compile("^([*][*][" + es + "]).*").matcher(pattern);
		if (ss.matches()) {
			pattern = pattern.substring(ss.group(1).length());
			// make leading sep optional
			sb.append("(.*[" + es + "])?");
		}
		// special trailer
		Matcher st = Pattern.compile(".*([" + es + "][*][*])$").matcher(pattern);
		boolean useSt = false;
		if (st.matches()) {
			pattern = pattern.substring(0, st.start(1));
			useSt = true;
		}
		
		for(int i = 0; i != pattern.length(); ++i) {
			char c = pattern.charAt(i);
			if (c == '?') {
				sb.append("[^" + es + "]");
			}
			else if (c == '*') {
				if (i + 1 < pattern.length() && pattern.charAt(i+1) == '*') {
					i++;
					// **
					sb.append(".*");
				}
				else {
					sb.append("[^" + es + "]*");
				}
			}
			else {
				if (c == '$') {
					sb.append("\\$");
				}
				else if (Character.isJavaIdentifierPart(c) || Character.isWhitespace(c)) {
					sb.append(c);
				}
				else {
					sb.append('\\').append(c);
				}
			}
		}
		
		if (useSt) {
			sb.append("([" + es + "].*)?");
		}
		
		return Pattern.compile(sb.toString());
	}

	private static String escape(String separator) {
		StringBuffer sb = new StringBuffer();
		for(int i = 0; i != separator.length(); ++i) {
			char c = separator.charAt(i);
			if ("\\[]&-".indexOf(c) >= 0){
				sb.append('\\').append(c);
			}
			else {
				sb.append(c);
			}
		}
		return sb.toString();
	}
}