WildcardMatcher.java

package org.theonefx.wcframework.utils;

/**
 * This class provides a method for the programmar to test whether a f ile
 * matches a wildcard.
 * 
 * For he who is familiar with dos, he will probably refer to files us ing
 * wildcard, that is file names like "*.bat","a?b.*",etc, this class gives you a
 * method to test if they are match.
 * 
 * A "*" can match any length of string including an empty string, A "?" can
 * match any single char.
 * 
 * So "abc" & "a*" matches "abc" & "*" matches "abc" & "b*" doesn"t match "abcd"
 * & "a*d" matches "abcd" & "a??d" matches ......
 */

public class WildcardMatcher {
	/**
	 * Tag to indicate if the strings should be compared case sensitive or not.
	 */
	private static boolean ignoreCase = false;

	/**
	 * Empty construct, since all the methods are static, you don"t ha ve to
	 * make an object of this class, and thus I hide the construtor in private.
	 */
	private WildcardMatcher() {
	}

	/**
	 * Give the boolean value whether the given file name and the wild card
	 * matches.
	 * 
	 * @param string
	 *            The source string to be compared to the wildcard.
	 * @param wildcard
	 *            The wildcard.
	 * 
	 * @return True, if they matches.
	 */
	public static boolean match(String string, String wildcard) {
		return match(string, wildcard, false);
	}

	/**
	 * Give the boolean value whether the given file name and the wild card
	 * matches.
	 * 
	 * @param string
	 *            The source string to be compared to the wildcard.
	 * @param wildcard
	 *            The wildcard.
	 * 
	 * 
	 * @param ignorecase
	 *            If this param is true, all the comparison is made not
	 *            casesensitive.
	 * 
	 * @return True, if they matches.
	 */
	public static boolean match(String string, String wildcard, boolean ignorecase) {
		ignoreCase = ignorecase;
		if (wildcard.indexOf("*") < 0)
			return stringEquals(string, wildcard);
		if (wildcard.equals("*"))
			return true;
		String sub = null;
		int pw = 0, ps = 0, wlen = wildcard.length(), index;
		boolean first = true;
		while (pw < wlen) {
			index = wildcard.indexOf("*", pw);
			if (index < 0) {
				sub = wildcard.substring(pw);
				pw = wlen; // to skip out
			} else {
				sub = wildcard.substring(pw, index);
				pw = index + 1;
			}
			index = find(string, sub, ps);
			if (first) {
				first = false;
				if (index != 0) {
					return false;
				} else
					ps = sub.length();
			} else {
				if (index < 0) {
					return false;
				}
				ps = index + sub.length();
			}
		}
		if (wildcard.charAt(wildcard.length() - 1) != '*') {
			index = find(string, sub, string.length() - sub.length());
			if (index < 0)
				return false;
		}
		return true;
	}

	/**
	 * Inner method to test whether two string equals, it is same as S
	 * tring.equals, except that it supports wildcard "?"
	 * 
	 * @param a
	 *            A string to compare
	 * @param b
	 *            A string to compare
	 * 
	 * @return True If a and b equals, notice that this could be invol ve
	 *         wildcard "?"
	 */
	private static boolean stringEquals(String a, String b) {
		int alen = a.length(), blen = b.length();
		if (alen != blen)
			return false;
		if (find(a, b, 0) == 0)
			return true;
		return false;
	}

	/**
	 * Find the match position of the two string, it is same as String .indexOf,
	 * except that it supports wildcard "?"
	 * 
	 * @param string
	 *            The source string to be compared to the pattern.
	 * @param pattern
	 *            The wildcard contained string.
	 * @param startpos
	 *            The start position of this search.
	 * 
	 * @return The match position of the two string,-1 if they do not match.
	 */
	private static int find(String string, String pattern, int startpos) {
		if (pattern.equals("")) {
			return startpos;
		}
		int orgp, pp = 0, ps = startpos, strlen = string.length(), patternlen = pattern.length();
		char pc, sc;
		boolean cmatch;
		orgp = ps;
		while (ps < strlen) {
			sc = string.charAt(ps);
			pc = pattern.charAt(pp);
			if (ignoreCase) {
				cmatch = (charEqualsIgnoreCase(sc, pc) || pc == '?');

			} else {
				cmatch = (sc == pc || pc == '?');
			}
			if (!cmatch) {
				pp = 0;
				ps = ++orgp;
				continue;
			}
			pp++;
			ps++;
			if (pp == patternlen) {
				return orgp;
			}
		}
		return -1;
	}

	/**
	 * Compare two char but ignore their case.
	 * 
	 * @param a
	 *            Char to compare.
	 * @param b
	 *            Char to compare.
	 * 
	 * @return True, if they equals or they equals while ignoring their case.
	 */
	private static boolean charEqualsIgnoreCase(char a, char b) {
		if (a == b)
			return true;
		char t;
		if (a > b) {
			t = a;
			a = b;
			b = t;
		} // now a<b
		int at = getCharType(a);
		int bt = getCharType(b);
		if (at == UPPERCASE && bt == LOWERCASE && a + 'a' - 'A' == b)
			return true;
		return false;
	}

	/**
	 * This is a inner method called by charEqualsIgnoreCase, which gi ves the
	 * type of the cha.
	 * 
	 * @param c
	 *            The char to find type.
	 * 
	 * @return LOWERCASE--if the char is in lowercase. UPPERCASE--if the char is
	 *         in uppercase. NOT_A_LETTER--if the char is not a letter.
	 */
	private static int getCharType(char c) {
		if (c >= 'a' && c <= 'z') {
			return LOWERCASE;
		}
		if (c >= 'A' && c <= 'Z') {
			return UPPERCASE;
		}
		return NOT_A_LETTER;
	}

	/**
	 * Constant value for char type that is in lowercase.
	 */
	final private static int LOWERCASE = 10;

	/**
	 * Constant value for char type that is in uppercase.
	 */
	final private static int UPPERCASE = 20;

	/**
	 * Constant value for char type that is not a letter.
	 */
	final private static int NOT_A_LETTER = 30;

	public static void main(String[] args) {
		String source = "jack aha love aha rose aha!";
		String match = "Jack?aha*";
		System.out.println(WildcardMatcher.match(source, match));
	}

}