package org.unifiedtech.guardian;

import java.util.HashMap;
import java.util.regex.Pattern;

public class StringUtils {

    private static HashMap<String, Pattern> regexCache = new HashMap<String, Pattern>();

    /**
     * Returns whether the specified String is null or empty.
     *
     * @param str
     * @return
     */
    public static boolean isNullOrEmpty(String str) {
        return (str == null || str.trim().length() == 0);
    }

    /**
     * Checks whether the specified string matches the specified regex pattern.
     * Utilizes a caching mechanism to cache patterns that are used repeatedly in the same program, avoiding useless cpu cycles.
     *
     * @param string
     * @param pattern
     * @return
     */
    public static boolean matches(String string, String pattern) {
        synchronized(regexCache) {
            Pattern p;

            if (regexCache.containsKey(pattern)) {
                p = regexCache.get(pattern);
            } else {
                p = Pattern.compile(pattern);
                regexCache.put(pattern, p);
            }

            return p.matcher(string).matches();
        }
    }
}