@kayahr/text-encoding
Version:
Text encoder and decoder
48 lines • 1.37 kB
JavaScript
/*
* Copyright (C) 2021 Klaus Reimer <k@ailis.de>
* See LICENSE.md for licensing information.
*/
import { AbstractEncoder } from "../AbstractEncoder.js";
import { END_OF_BUFFER } from "../ByteBuffer.js";
import { FINISHED } from "../constants.js";
import { inRange, isASCII } from "../util.js";
/**
* Encoder for utf-8 encoding.
*/
export class UTF8Encoder extends AbstractEncoder {
/** @inheritdoc */
encode(buffer) {
const codePoint = buffer.read();
if (codePoint === END_OF_BUFFER) {
return FINISHED;
}
if (isASCII(codePoint)) {
return codePoint;
}
let count;
let offset;
if (inRange(codePoint, 0x0080, 0x07FF)) {
count = 1;
offset = 0xC0;
}
else if (inRange(codePoint, 0x0800, 0xFFFF)) {
count = 2;
offset = 0xE0;
}
else if (inRange(codePoint, 0x10000, 0x10FFFF)) {
count = 3;
offset = 0xF0;
}
else {
return this.fail(codePoint);
}
const bytes = [(codePoint >> (6 * count)) + offset];
while (count > 0) {
const temp = codePoint >> (6 * (count - 1));
bytes.push(0x80 | (temp & 0x3F));
count -= 1;
}
return bytes;
}
}
//# sourceMappingURL=UTF8Encoder.js.map