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// Copyright 2010 The Closure Library Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @fileoverview Functions for encoding strings according to MIME
* standards, especially RFC 1522.
*/
goog.provide('goog.i18n.mime');
goog.provide('goog.i18n.mime.encode');
/**
* Regular expression for matching those characters that are outside the
* range that can be used in the quoted-printable encoding of RFC 1522:
* anything outside the 7-bit ASCII encoding, plus ?, =, _ or space.
* @type {RegExp}
* @private
*/
goog.i18n.mime.NONASCII_ = /[^!-<>@-^`-~]/g;
/**
* Like goog.i18n.NONASCII_ but also omits double-quotes.
* @type {RegExp}
* @private
*/
goog.i18n.mime.NONASCII_NOQUOTE_ = /[^!#-<>@-^`-~]/g;
/**
* Encodes a string for inclusion in a MIME header. The string is encoded
* in UTF-8 according to RFC 1522, using quoted-printable form.
* @param {string} str The string to encode.
* @param {boolean=} opt_noquote Whether double-quote characters should also
* be escaped (should be true if the result will be placed inside a
* quoted string for a parameter value in a MIME header).
* @return {string} The encoded string.
*/
goog.i18n.mime.encode = function(str, opt_noquote) {
var nonascii = opt_noquote ?
goog.i18n.mime.NONASCII_NOQUOTE_ : goog.i18n.mime.NONASCII_;
if (str.search(nonascii) >= 0) {
str = '=?UTF-8?Q?' + str.replace(nonascii,
/**
* @param {string} c The matched char.
* @return {string} The quoted-printable form of utf-8 encoding.
*/
function(c) {
var i = c.charCodeAt(0);
if (i == 32) {
// Special case for space, which can be encoded as _ not =20
return '_';
}
var a = ['']; // start with empty string to get = before every char
// First convert the UCS-2 character into its UTF-8 bytes
if (i < 128) {
a.push(i);
} else if (i <= 0x7ff) {
a.push(
0xc0 + ((i >> 6) & 0x3f),
0x80 + (i & 0x3f));
} else if (i <= 0xffff) {
a.push(
0xe0 + ((i >> 12) & 0x3f),
0x80 + ((i >> 6) & 0x3f),
0x80 + (i & 0x3f));
} else {
// (This is defensive programming, since ecmascript isn't supposed
// to handle code points that take more than 16 bits.)
a.push(
0xf0 + ((i >> 18) & 0x3f),
0x80 + ((i >> 12) & 0x3f),
0x80 + ((i >> 6) & 0x3f),
0x80 + (i & 0x3f));
}
// Now convert those bytes into hex strings (don't do anything with
// a[0] as that's got the empty string that lets us use join(),
// below).
for (i = a.length - 1; i > 0; --i) {
a[i] = a[i].toString(16);
}
// Form the string with = before each byte.
return a.join('=');
}) + '?=';
}
return str;
};
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