/* ====================================================================
 * Copyright (c) 2006 J.T. Beetstra
 *
 * Permission is hereby granted, free of charge, to any person obtaining 
 * a copy of this software and associated documentation files (the 
 * "Software"), to deal in the Software without restriction, including 
 * without limitation the rights to use, copy, modify, merge, publish, 
 * distribute, sublicense, and/or sell copies of the Software, and to 
 * permit persons to whom the Software is furnished to do so, subject to 
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be 
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY 
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE 
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 * ====================================================================
 */
package com.beetstra.jutf7;


/**
 * <p>The character set specified in RFC 3501 to use for IMAP4rev1 mailbox name encoding.</p>
 * 
 * @see <a href="http://tools.ietf.org/html/rfc3501">RFC 3501</a>
 * @author Jaap Beetstra
 */
class ModifiedUTF7Charset extends UTF7StyleCharset {
	private static final String MODIFIED_BASE64_ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
			+ "abcdefghijklmnopqrstuvwxyz" + "0123456789+,";

	ModifiedUTF7Charset(String name, String[] aliases) {
		super(name, aliases, MODIFIED_BASE64_ALPHABET, true);
	}

	boolean canEncodeDirectly(char ch) {
		if (ch == shift())
			return false;
		return ch >= 0x20 && ch <= 0x7E;
	}

	byte shift() {
		return '&';
	}

	byte unshift() {
		return '-';
	}
}
