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musix-oss/node_modules/fast-text-encoding/text.js
2020-03-03 22:30:50 +02:00

188 lines
5.5 KiB
JavaScript

/*
* Copyright 2017 Sam Thorogood. 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 Polyfill for TextEncoder and TextDecoder.
*
* You probably want `text.min.js`, and not this file directly.
*/
(function(scope) {
'use strict';
// fail early
if (scope['TextEncoder'] && scope['TextDecoder']) {
return false;
}
/**
* @constructor
* @param {string=} utfLabel
*/
function FastTextEncoder(utfLabel='utf-8') {
if (utfLabel !== 'utf-8') {
throw new RangeError(
`Failed to construct 'TextEncoder': The encoding label provided ('${utfLabel}') is invalid.`);
}
}
Object.defineProperty(FastTextEncoder.prototype, 'encoding', {value: 'utf-8'});
/**
* @param {string} string
* @param {{stream: boolean}=} options
* @return {!Uint8Array}
*/
FastTextEncoder.prototype.encode = function(string, options={stream: false}) {
if (options.stream) {
throw new Error(`Failed to encode: the 'stream' option is unsupported.`);
}
let pos = 0;
const len = string.length;
const out = [];
let at = 0; // output position
let tlen = Math.max(32, len + (len >> 1) + 7); // 1.5x size
let target = new Uint8Array((tlen >> 3) << 3); // ... but at 8 byte offset
while (pos < len) {
let value = string.charCodeAt(pos++);
if (value >= 0xd800 && value <= 0xdbff) {
// high surrogate
if (pos < len) {
const extra = string.charCodeAt(pos);
if ((extra & 0xfc00) === 0xdc00) {
++pos;
value = ((value & 0x3ff) << 10) + (extra & 0x3ff) + 0x10000;
}
}
if (value >= 0xd800 && value <= 0xdbff) {
continue; // drop lone surrogate
}
}
// expand the buffer if we couldn't write 4 bytes
if (at + 4 > target.length) {
tlen += 8; // minimum extra
tlen *= (1.0 + (pos / string.length) * 2); // take 2x the remaining
tlen = (tlen >> 3) << 3; // 8 byte offset
const update = new Uint8Array(tlen);
update.set(target);
target = update;
}
if ((value & 0xffffff80) === 0) { // 1-byte
target[at++] = value; // ASCII
continue;
} else if ((value & 0xfffff800) === 0) { // 2-byte
target[at++] = ((value >> 6) & 0x1f) | 0xc0;
} else if ((value & 0xffff0000) === 0) { // 3-byte
target[at++] = ((value >> 12) & 0x0f) | 0xe0;
target[at++] = ((value >> 6) & 0x3f) | 0x80;
} else if ((value & 0xffe00000) === 0) { // 4-byte
target[at++] = ((value >> 18) & 0x07) | 0xf0;
target[at++] = ((value >> 12) & 0x3f) | 0x80;
target[at++] = ((value >> 6) & 0x3f) | 0x80;
} else {
// FIXME: do we care
continue;
}
target[at++] = (value & 0x3f) | 0x80;
}
return target.slice(0, at);
}
/**
* @constructor
* @param {string=} utfLabel
* @param {{fatal: boolean}=} options
*/
function FastTextDecoder(utfLabel='utf-8', options={fatal: false}) {
if (utfLabel !== 'utf-8') {
throw new RangeError(
`Failed to construct 'TextDecoder': The encoding label provided ('${utfLabel}') is invalid.`);
}
if (options.fatal) {
throw new Error(`Failed to construct 'TextDecoder': the 'fatal' option is unsupported.`);
}
}
Object.defineProperty(FastTextDecoder.prototype, 'encoding', {value: 'utf-8'});
Object.defineProperty(FastTextDecoder.prototype, 'fatal', {value: false});
Object.defineProperty(FastTextDecoder.prototype, 'ignoreBOM', {value: false});
/**
* @param {(!ArrayBuffer|!ArrayBufferView)} buffer
* @param {{stream: boolean}=} options
*/
FastTextDecoder.prototype.decode = function(buffer, options={stream: false}) {
if (options['stream']) {
throw new Error(`Failed to decode: the 'stream' option is unsupported.`);
}
const bytes = new Uint8Array(buffer);
let pos = 0;
const len = bytes.length;
const out = [];
while (pos < len) {
const byte1 = bytes[pos++];
if (byte1 === 0) {
break; // NULL
}
if ((byte1 & 0x80) === 0) { // 1-byte
out.push(byte1);
} else if ((byte1 & 0xe0) === 0xc0) { // 2-byte
const byte2 = bytes[pos++] & 0x3f;
out.push(((byte1 & 0x1f) << 6) | byte2);
} else if ((byte1 & 0xf0) === 0xe0) {
const byte2 = bytes[pos++] & 0x3f;
const byte3 = bytes[pos++] & 0x3f;
out.push(((byte1 & 0x1f) << 12) | (byte2 << 6) | byte3);
} else if ((byte1 & 0xf8) === 0xf0) {
const byte2 = bytes[pos++] & 0x3f;
const byte3 = bytes[pos++] & 0x3f;
const byte4 = bytes[pos++] & 0x3f;
// this can be > 0xffff, so possibly generate surrogates
let codepoint = ((byte1 & 0x07) << 0x12) | (byte2 << 0x0c) | (byte3 << 0x06) | byte4;
if (codepoint > 0xffff) {
// codepoint &= ~0x10000;
codepoint -= 0x10000;
out.push((codepoint >>> 10) & 0x3ff | 0xd800)
codepoint = 0xdc00 | codepoint & 0x3ff;
}
out.push(codepoint);
} else {
// FIXME: we're ignoring this
}
}
return String.fromCharCode.apply(null, out);
}
scope['TextEncoder'] = FastTextEncoder;
scope['TextDecoder'] = FastTextDecoder;
}(typeof window !== 'undefined' ? window : (typeof global !== 'undefined' ? global : this)));