package com.yuji.tdb.utility;

import java.util.regex.Pattern;

public class StringUtil {
	private static Pattern ptnAlnum = Pattern.compile("[a-zA-Z0-9]");
	private static Pattern ptnAscii = Pattern.compile("\\p{ASCII}");
	
	public static String parseSubstring(String text, int length){
		int len = text.length();
		int status = -1;
		int pos = 0;
		
		for (int i = 0; i < len && i < length; i++){
			String ch = text.substring(i, i + 1);
			
			if (ptnAlnum.matcher(ch).matches()){
				if (status != 0){
					pos = i;
					status = 0;
				}
			}
			else if (ptnAscii.matcher(ch).matches()){
				if (status != 1){
					pos = i;
					status = 1;
				}				
			}
			else {
				if (status != 2){
					pos = i;
					status = 2;
				}								
			}
		}
		return text.substring(0, pos + 1);
	}
}