JSEscape.java

package org.ripple.power.utils;

public class JSEscape {
	public static String unescape(String escaped) {
		int length = escaped.length();
		int i = 0;
		StringBuilder sb = new StringBuilder(escaped.length() / 2);

		while (i < length) {
			char n = escaped.charAt(i++);
			if (n != '%') {
				sb.append(n);
			} else {
				n = escaped.charAt(i++);
				int code;

				if (n == 'u') {
					String slice = escaped.substring(i, i + 4);
					code = Integer.valueOf(slice, 16);
					i += 4;
				} else {
					String slice = escaped.substring(i - 1, ++i);
					code = Integer.valueOf(slice, 16);
				}
				sb.append((char) code);
			}
		}

		return sb.toString();
	}

	public static String escape(String raw) {
		int length = raw.length();
		int i = 0;
		StringBuilder sb = new StringBuilder(raw.length() / 2);

		while (i < length) {
			char c = raw.charAt(i++);

			if (isLetterOrDigit(c) || isEscapeExempt(c)) {
				sb.append(c);
			} else {
				int i1 = raw.codePointAt(i - 1);
				String escape = Integer.toHexString(i1);

				sb.append('%');

				if (escape.length() > 2) {
					sb.append('u');
				}
				sb.append(escape.toUpperCase());

			}
		}

		return sb.toString();
	}

	private static boolean isLetterOrDigit(char ch) {
		return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')
				|| (ch >= '0' && ch <= '9');
	}

	private static boolean isEscapeExempt(char c) {
		switch (c) {
		case '*':
		case '@':
		case '-':
		case '_':
		case '+':
		case '.':
		case '/':
			return true;
		default:
			return false;
		}
	}
}