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Use text-encoding-utf-8 as a TextEncoder polyfill

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Somebody else seems to have done a good job of polyfilling TextEncoder, so
let's use that.
This commit is contained in:
Richard van der Hoff
2017-01-18 11:39:44 +00:00
parent 09ce74cc76
commit 31df78f946
7 changed files with 89 additions and 336 deletions
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7
src/utils/MegolmExportEncryption.js
View File

@@ -17,13 +17,14 @@ limitations under the License.
"use strict";
// polyfill textencoder if necessary
import * as TextEncodingUtf8 from 'text-encoding-utf-8';
let TextEncoder = window.TextEncoder;
if (!TextEncoder) {
TextEncoder = require('./TextEncoderPolyfill');
TextEncoder = TextEncodingUtf8.TextEncoder;
}
let TextDecoder = window.TextDecoder;
if (TextDecoder) {
TextDecoder = require('./TextDecoderPolyfill');
if (!TextDecoder) {
TextDecoder = TextEncodingUtf8.TextDecoder;
}
const subtleCrypto = window.crypto.subtle || window.crypto.webkitSubtle;

131
src/utils/TextDecoderPolyfill.js
View File

@@ -1,131 +0,0 @@
/*
Copyright 2017 Vector Creations Ltd
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.
*/
"use strict";
// Polyfill for TextDecoder.
const REPLACEMENT_CHAR = '\uFFFD';
export default class TextDecoder {
/**
* Decode a UTF-8 byte array as a javascript string
*
* @param {Uint8Array} u8Array UTF-8-encoded onput
* @return {str}
*/
decode(u8Array) {
let u0, u1, u2, u3;
let str = '';
let idx = 0;
while (idx < u8Array.length) {
u0 = u8Array[idx++];
if (!(u0 & 0x80)) {
str += String.fromCharCode(u0);
continue;
}
if ((u0 & 0xC0) != 0xC0) {
// continuation byte where we expect a leading byte
str += REPLACEMENT_CHAR;
continue;
}
if (u0 > 0xF4) {
// this would imply a 5-byte or longer encoding, which is
// invalid and unsupported here.
str += REPLACEMENT_CHAR;
continue;
}
u1 = u8Array[idx++];
if (u1 === undefined) {
str += REPLACEMENT_CHAR;
continue;
}
if ((u1 & 0xC0) != 0x80) {
// leading byte where we expect a continuation byte
str += REPLACEMENT_CHAR.repeat(2);
continue;
}
u1 &= 0x3F;
if (!(u0 & 0x20)) {
const u = ((u0 & 0x1F) << 6) | u1;
if (u < 0x80) {
// over-long
str += REPLACEMENT_CHAR.repeat(2);
} else {
str += String.fromCharCode(u);
}
continue;
}
u2 = u8Array[idx++];
if (u2 === undefined) {
str += REPLACEMENT_CHAR.repeat(2);
continue;
}
if ((u2 & 0xC0) != 0x80) {
// leading byte where we expect a continuation byte
str += REPLACEMENT_CHAR.repeat(3);
continue;
}
u2 &= 0x3F;
if (!(u0 & 0x10)) {
const u = ((u0 & 0x0F) << 12) | (u1 << 6) | u2;
if (u < 0x800) {
// over-long
str += REPLACEMENT_CHAR.repeat(3);
} else if (u == 0xFEFF && idx == 3) {
// byte-order mark: do not add to output
} else {
str += String.fromCharCode(u);
}
continue;
}
u3 = u8Array[idx++];
if (u3 === undefined) {
str += REPLACEMENT_CHAR.repeat(3);
continue;
}
if ((u3 & 0xC0) != 0x80) {
// leading byte where we expect a continuation byte
str += REPLACEMENT_CHAR.repeat(4);
continue;
}
u3 &= 0x3F;
const u = ((u0 & 7) << 18) | (u1 << 12) | (u2 << 6) | u3;
if (u < 0x10000) {
// over-long
str += REPLACEMENT_CHAR.repeat(4);
continue;
}
if (u > 0x1FFFF) {
// unicode stops here.
str += REPLACEMENT_CHAR.repeat(4);
continue;
}
// encode as utf-16
const v = u - 0x10000;
str += String.fromCharCode(0xD800 | (v >> 10), 0xDC00 | (v & 0x3FF));
}
return str;
}
}

78
src/utils/TextEncoderPolyfill.js
View File

@@ -1,78 +0,0 @@
/*
Copyright 2017 Vector Creations Ltd
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.
*/
"use strict";
// Polyfill for TextEncoder. Based on emscripten's stringToUTF8Array.
function utf8len(str) {
var len = 0;
for (var i = 0; i < str.length; ++i) {
var u = str.charCodeAt(i);
if (u >= 0xD800 && u <= 0xDFFF && i < str.length-1) {
// lead surrogate - combine with next surrogate
u = 0x10000 + ((u & 0x3FF) << 10) | (str.charCodeAt(++i) & 0x3FF);
}
if (u <= 0x7F) {
++len;
} else if (u <= 0x7FF) {
len += 2;
} else if (u <= 0xFFFF) {
len += 3;
} else {
len += 4;
}
}
return len;
}
export default class TextEncoder {
/**
* Encode a javascript string as utf-8
*
* @param {String} str String to encode
* @return {Uint8Array} UTF-8-encoded output
*/
encode(str) {
const outU8Array = new Uint8Array(utf8len(str));
var outIdx = 0;
for (var i = 0; i < str.length; ++i) {
var u = str.charCodeAt(i);
if (u >= 0xD800 && u <= 0xDFFF && i < str.length-1) {
// lead surrogate - combine with next surrogate
u = 0x10000 + ((u & 0x3FF) << 10) | (str.charCodeAt(++i) & 0x3FF);
}
if (u <= 0x7F) {
outU8Array[outIdx++] = u;
} else if (u <= 0x7FF) {
outU8Array[outIdx++] = 0xC0 | (u >> 6);
outU8Array[outIdx++] = 0x80 | (u & 0x3F);
} else if (u <= 0xFFFF) {
outU8Array[outIdx++] = 0xE0 | (u >> 12);
outU8Array[outIdx++] = 0x80 | ((u >> 6) & 0x3F);
outU8Array[outIdx++] = 0x80 | (u & 0x3F);
} else {
outU8Array[outIdx++] = 0xF0 | (u >> 18);
outU8Array[outIdx++] = 0x80 | ((u >> 12) & 0x3F);
outU8Array[outIdx++] = 0x80 | ((u >> 6) & 0x3F);
outU8Array[outIdx++] = 0x80 | (u & 0x3F);
}
}
return outU8Array;
}
}