48 lines
1.3 KiB
JavaScript
48 lines
1.3 KiB
JavaScript
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"use strict";
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const iconvLite = require("iconv-lite");
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const supportedNames = require("./supported-names.json");
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const labelsToNames = require("./labels-to-names.json");
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const supportedNamesSet = new Set(supportedNames);
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// https://encoding.spec.whatwg.org/#concept-encoding-get
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exports.labelToName = label => {
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label = String(label).trim().toLowerCase();
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return labelsToNames[label] || null;
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};
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// https://encoding.spec.whatwg.org/#decode
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exports.decode = (buffer, fallbackEncodingName) => {
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let encoding = fallbackEncodingName;
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if (!exports.isSupported(encoding)) {
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throw new RangeError(`"${encoding}" is not a supported encoding name`);
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}
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const bomEncoding = exports.getBOMEncoding(buffer);
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if (bomEncoding !== null) {
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encoding = bomEncoding;
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}
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// iconv-lite will strip BOMs for us, so no need to do the stuff the spec does
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return iconvLite.decode(buffer, encoding);
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};
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// https://github.com/whatwg/html/issues/1910#issuecomment-254017369
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exports.getBOMEncoding = buffer => {
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if (buffer[0] === 0xFE && buffer[1] === 0xFF) {
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return "UTF-16BE";
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} else if (buffer[0] === 0xFF && buffer[1] === 0xFE) {
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return "UTF-16LE";
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} else if (buffer[0] === 0xEF && buffer[1] === 0xBB && buffer[2] === 0xBF) {
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return "UTF-8";
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}
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return null;
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};
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exports.isSupported = name => {
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return supportedNamesSet.has(String(name));
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};
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