agsamantha/node_modules/whatwg-encoding/lib/whatwg-encoding.js
2024-10-02 15:15:21 -05:00

60 lines
1.8 KiB
JavaScript

"use strict";
const iconvLite = require("iconv-lite");
const supportedNames = require("./supported-names.json");
const labelsToNames = require("./labels-to-names.json");
const supportedNamesSet = new Set(supportedNames);
// https://encoding.spec.whatwg.org/#concept-encoding-get
exports.labelToName = label => {
label = String(label).trim().toLowerCase();
return labelsToNames[label] || null;
};
// https://encoding.spec.whatwg.org/#decode
exports.decode = (uint8Array, fallbackEncodingName) => {
let encoding = fallbackEncodingName;
if (!exports.isSupported(encoding)) {
throw new RangeError(`"${encoding}" is not a supported encoding name`);
}
const bomEncoding = exports.getBOMEncoding(uint8Array);
if (bomEncoding !== null) {
encoding = bomEncoding;
// iconv-lite will strip BOMs for us, so no need to do the extra byte removal that the spec does.
// Note that we won't end up in the x-user-defined case when there's a bomEncoding.
}
if (encoding === "x-user-defined") {
// https://encoding.spec.whatwg.org/#x-user-defined-decoder
let result = "";
for (const byte of uint8Array) {
if (byte <= 0x7F) {
result += String.fromCodePoint(byte);
} else {
result += String.fromCodePoint(0xF780 + byte - 0x80);
}
}
return result;
}
return iconvLite.decode(uint8Array, encoding);
};
// https://github.com/whatwg/html/issues/1910#issuecomment-254017369
exports.getBOMEncoding = uint8Array => {
if (uint8Array[0] === 0xFE && uint8Array[1] === 0xFF) {
return "UTF-16BE";
} else if (uint8Array[0] === 0xFF && uint8Array[1] === 0xFE) {
return "UTF-16LE";
} else if (uint8Array[0] === 0xEF && uint8Array[1] === 0xBB && uint8Array[2] === 0xBF) {
return "UTF-8";
}
return null;
};
exports.isSupported = name => {
return supportedNamesSet.has(String(name));
};