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/* |
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* Copyright (c) 2018 Rafael da Silva Rocha. |
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* |
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* Permission is hereby granted, free of charge, to any person obtaining |
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* a copy of this software and associated documentation files (the |
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* "Software"), to deal in the Software without restriction, including |
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* without limitation the rights to use, copy, modify, merge, publish, |
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* distribute, sublicense, and/or sell copies of the Software, and to |
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* permit persons to whom the Software is furnished to do so, subject to |
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* the following conditions: |
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* |
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* The above copyright notice and this permission notice shall be |
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* included in all copies or substantial portions of the Software. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE |
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION |
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION |
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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* |
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*/ |
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/** |
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* @fileoverview Functions to serialize and deserialize UTF-8 strings. |
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* @see https://github.com/rochars/byte-data |
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* @see https://encoding.spec.whatwg.org/#the-encoding |
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* @see https://encoding.spec.whatwg.org/#utf-8-encoder |
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*/ |
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/** |
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* Read a string of UTF-8 characters from a byte buffer. |
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* Invalid characters are replaced with 'REPLACEMENT CHARACTER' (U+FFFD). |
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* @see https://encoding.spec.whatwg.org/#the-encoding |
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* @see https://stackoverflow.com/a/34926911 |
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* @param {!Uint8Array|!Array<number>} buffer A byte buffer. |
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* @param {number} [start=0] The buffer index to start reading. |
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* @param {number} [end=0] The buffer index to stop reading. |
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* Assumes the buffer length if undefined. |
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* @return {string} |
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*/ |
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export function unpack(buffer, start=0, end=buffer.length) { |
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/** @type {string} */ |
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let str = ''; |
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for(let index = start; index < end;) { |
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/** @type {number} */ |
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let lowerBoundary = 0x80; |
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/** @type {number} */ |
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let upperBoundary = 0xBF; |
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/** @type {boolean} */ |
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let replace = false; |
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/** @type {number} */ |
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let charCode = buffer[index++]; |
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if (charCode >= 0x00 && charCode <= 0x7F) { |
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str += String.fromCharCode(charCode); |
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} else { |
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/** @type {number} */ |
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let count = 0; |
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if (charCode >= 0xC2 && charCode <= 0xDF) { |
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count = 1; |
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} else if (charCode >= 0xE0 && charCode <= 0xEF ) { |
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count = 2; |
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if (buffer[index] === 0xE0) { |
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lowerBoundary = 0xA0; |
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} |
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if (buffer[index] === 0xED) { |
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upperBoundary = 0x9F; |
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} |
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} else if (charCode >= 0xF0 && charCode <= 0xF4 ) { |
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count = 3; |
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if (buffer[index] === 0xF0) { |
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lowerBoundary = 0x90; |
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} |
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if (buffer[index] === 0xF4) { |
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upperBoundary = 0x8F; |
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} |
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} else { |
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replace = true; |
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} |
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charCode = charCode & (1 << (8 - count - 1)) - 1; |
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for (let i = 0; i < count; i++) { |
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if (buffer[index] < lowerBoundary || buffer[index] > upperBoundary) { |
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replace = true; |
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} |
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charCode = (charCode << 6) | (buffer[index] & 0x3f); |
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index++; |
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} |
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if (replace) { |
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str += String.fromCharCode(0xFFFD); |
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} |
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else if (charCode <= 0xffff) { |
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str += String.fromCharCode(charCode); |
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} else { |
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charCode -= 0x10000; |
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str += String.fromCharCode( |
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((charCode >> 10) & 0x3ff) + 0xd800, |
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(charCode & 0x3ff) + 0xdc00); |
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} |
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} |
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} |
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return str; |
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} |
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/** |
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* Write a string of UTF-8 characters to a byte buffer. |
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* @see https://encoding.spec.whatwg.org/#utf-8-encoder |
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* @param {string} str The string to pack. |
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* @param {!Uint8Array|!Array<number>} buffer The buffer to pack the string to. |
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* @param {number=} index The buffer index to start writing. |
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* @return {number} The next index to write in the buffer. |
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* @throws {TypeError} If 'str' is not a string. |
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*/ |
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export function pack(str, buffer, index=0) { |
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if (typeof str !== 'string') { |
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throw new TypeError(); |
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} |
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/** @type {number} */ |
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let i = 0; |
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/** @type {number} */ |
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let len = str.length; |
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while (i < len) { |
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/** @type {number} */ |
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let codePoint = str.codePointAt(i); |
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if (codePoint < 128) { |
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buffer[index] = codePoint; |
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index++; |
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} else { |
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/** @type {number} */ |
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let count = 0; |
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/** @type {number} */ |
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let offset = 0; |
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if (codePoint <= 0x07FF) { |
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count = 1; |
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offset = 0xC0; |
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} else if(codePoint <= 0xFFFF) { |
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count = 2; |
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offset = 0xE0; |
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} else if(codePoint <= 0x10FFFF) { |
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count = 3; |
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offset = 0xF0; |
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i++; |
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} |
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buffer[index] = (codePoint >> (6 * count)) + offset; |
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index++; |
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while (count > 0) { |
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buffer[index] = 0x80 | (codePoint >> (6 * (count - 1)) & 0x3F); |
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index++; |
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count--; |
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} |
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} |
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i++; |
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} |
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return index; |
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} |
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rochars /
byte-data
