96 lines
2.7 KiB
JavaScript
96 lines
2.7 KiB
JavaScript
'use strict';
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const Iconv = require('iconv-lite');
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const { createLRU } = require('lru.min');
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const decoderCache = createLRU({
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max: 500,
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});
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// Direct slice methods skip the per-call encoding normalization and dispatch
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// inside buffer.toString(); they have been stable Node internals for years
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// but fall back gracefully where missing (other runtimes)
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const hasFastSlices =
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typeof Buffer.prototype.utf8Slice === 'function' &&
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typeof Buffer.prototype.latin1Slice === 'function' &&
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typeof Buffer.prototype.asciiSlice === 'function';
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// utf8Write skips the per-call encoding normalization and dispatch inside
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// buffer.write(); same stability story as the slice methods above
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exports.hasFastUtf8Write = typeof Buffer.prototype.utf8Write === 'function';
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exports.decode = function (buffer, encoding, start, end, options) {
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if (hasFastSlices) {
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// replicate buffer.toString() bounds coercion exactly (the *Slice
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// methods throw on anything out of range): negative, NaN, fractional
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// and oversized offsets all clamp instead of throwing
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const len = buffer.length;
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if (start <= 0) {
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start = 0;
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} else if (start >= len) {
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return '';
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} else {
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start |= 0;
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}
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if (end === undefined || end > len) {
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end = len;
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} else {
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end |= 0;
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}
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if (end <= start) {
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return '';
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}
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switch (encoding) {
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case 'utf8':
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case 'utf-8':
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return buffer.utf8Slice(start, end);
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case 'latin1':
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case 'binary':
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return buffer.latin1Slice(start, end);
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case 'ascii':
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return buffer.asciiSlice(start, end);
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default:
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break;
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}
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}
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if (Buffer.isEncoding(encoding)) {
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return buffer.toString(encoding, start, end);
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}
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// Optimize for common case: encoding="short_string", options=undefined.
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let decoder;
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if (!options) {
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decoder = decoderCache.get(encoding);
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if (!decoder) {
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decoder = Iconv.getDecoder(encoding);
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decoderCache.set(encoding, decoder);
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}
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} else {
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const decoderArgs = { encoding, options };
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const decoderKey = JSON.stringify(decoderArgs);
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decoder = decoderCache.get(decoderKey);
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if (!decoder) {
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decoder = Iconv.getDecoder(decoderArgs.encoding, decoderArgs.options);
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decoderCache.set(decoderKey, decoder);
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}
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}
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const res = decoder.write(buffer.slice(start, end));
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const trail = decoder.end();
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return trail ? res + trail : res;
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};
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exports.encode = function (string, encoding, options) {
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if (Buffer.isEncoding(encoding)) {
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return Buffer.from(string, encoding);
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}
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const encoder = Iconv.getEncoder(encoding, options || {});
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const res = encoder.write(string);
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const trail = encoder.end();
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return trail && trail.length > 0 ? Buffer.concat([res, trail]) : res;
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};
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