lib/internal/encoding/single-byte.js - main - githubmirror/node

lib/internal/encoding/single-byte.js
155 строк13 KB
Daijiro Wachi
lib: fix typo idenity => identity
13 май 2026, 15:22
13 май 2026, 15:22a159b57
// Simplified version extracted from https://npmjs.com/package/@exodus/bytes codepath for 1-byte encodings
// Copyright Exodus Movement. Licensed under MIT License.

'use strict';

const {
  Array,
  ArrayPrototypeFill,
  ObjectKeys,
  ObjectPrototypeHasOwnProperty,
  SafeArrayIterator,
  SafeMap,
  SafeSet,
  StringPrototypeIncludes,
  TypedArrayFrom,
  TypedArrayOf,
  TypedArrayPrototypeIncludes,
  TypedArrayPrototypeSet,
  Uint16Array,
} = primordials;

const { isAscii } = require('buffer');

const { FastBuffer } = require('internal/buffer');

const {
  ERR_ENCODING_NOT_SUPPORTED,
  ERR_ENCODING_INVALID_ENCODED_DATA,
} = require('internal/errors').codes;

const isBigEndian = new FastBuffer(TypedArrayOf(Uint16Array, 258).buffer)[1] === 2;

const it = (x) => new SafeArrayIterator(x);

/* fallback/single-byte.encodings.js */

const r = 0xfffd;
const e = (x) => it(ArrayPrototypeFill(new Array(x), 1));
const h = (x) => it(ArrayPrototypeFill(new Array(x), r));

/* eslint-disable @stylistic/js/max-len */

// Index tables from https://encoding.spec.whatwg.org/#legacy-single-byte-encodings
// Each table in the spec lists only mapping from byte 0x80 onwards, as below that they are all ASCII and mapped as identity
// Here, 0xfffd (replacement charcode) designates a hole (unmapped offset), as not all encodings map all offsets
// All other numbers are deltas from the last seen mapped value, starting with 0x7f (127, highest ASCII)
// Thus, [0x80, 0x81, , 0x83] is stored as [1, 1, r, 2]
// Truncation (length < 128) means that all remaining ones are mapped as identity (offset i => codepoint i), not unmapped
const encodings = {
  '__proto__': null,
  'ibm866': [913, ...e(47), 8530, 1, 1, -145, 34, 61, 1, -12, -1, 14, -18, 6, 6, -1, -1, -75, 4, 32, -8, -16, -28, 60, 34, 1, -5, -6, 21, -3, -6, -16, 28, -5, 1, -4, 1, -12, -1, -6, 1, 24, -1, -82, -12, 124, -4, 8, 4, -16, -8512, ...e(15), -78, 80, -77, 80, -77, 80, -73, 80, -942, 8553, -8546, 8547, -260, -8306, 9468, -9472],
  'iso-8859-10': [...e(33), 100, 14, 16, 8, -2, 14, -143, 148, -43, 80, 6, 23, -208, 189, -32, -154, 85, 14, 16, 8, -2, 14, -128, 133, -43, 80, 6, 23, 7831, -7850, -32, -75, -63, ...e(5), 104, -34, -67, 79, -77, 75, -73, 1, 1, 1, 117, 7, -121, 1, 1, 1, 146, -144, 154, -152, ...e(5), 34, -32, ...e(5), 73, -34, -36, 48, -46, 44, -42, 1, 1, 1, 86, 7, -90, 1, 1, 1, 115, -113, 123, -121, 1, 1, 1, 1, 58],
  'iso-8859-13': [...e(33), 8061, -8059, 1, 1, 8058, -8056, 1, 49, -47, 173, -171, 1, 1, 1, 24, -22, 1, 1, 1, 8041, -8039, 1, 1, 65, -63, 158, -156, 1, 1, 1, 40, 30, 42, -46, 6, -66, 1, 83, -6, -6, -67, 176, -99, 12, 20, -12, 17, 37, -29, 2, -114, 121, -119, 1, 1, 155, -49, 25, 16, -142, 159, 2, -158, 38, 42, -46, 6, -35, 1, 52, -6, -6, -36, 145, -99, 12, 20, -12, 17, 37, -29, 2, -83, 90, -88, 1, 1, 124, -49, 25, 16, -111, 128, 2, 7835],
  'iso-8859-14': [...e(33), 7522, 1, -7520, 103, 1, 7423, -7523, 7641, -7639, 7641, -119, 231, -7749, 1, 202, 7334, 1, -7423, 1, 7455, 1, -7563, 7584, 43, -42, 44, -35, 147, -111, 1, -36, -7585, ...e(15), 165, -163, ...e(5), 7572, -7570, ...e(5), 153, -151, ...e(16), 134, -132, ...e(5), 7541, -7539, ...e(5), 122],
  'iso-8859-15': [...e(33), 1, 1, 1, 8201, -8199, 187, -185, 186, -184, ...e(10), 202, -200, 1, 1, 199, -197, 1, 1, 151, 1, 37],
  'iso-8859-16': [...e(33), 100, 1, 60, 8043, -142, -7870, -185, 186, -184, 367, -365, 206, -204, 205, 1, -203, 1, 91, 54, 59, 7840, -8039, 1, 199, -113, 268, -350, 151, 1, 37, 4, -188, 1, 1, 64, -62, 66, -64, ...e(9), 65, 51, -113, 1, 1, 124, -122, 132, 22, -151, 1, 1, 1, 60, 258, -315, 1, 1, 1, 33, -31, 35, -33, ...e(9), 34, 51, -82, 1, 1, 93, -91, 101, 22, -120, 1, 1, 1, 29, 258],
  'iso-8859-2': [...e(33), 100, 468, -407, -157, 153, 29, -179, 1, 184, -2, 6, 21, -204, 208, -2, -203, 85, 470, -409, -142, 138, 29, 364, -527, 169, -2, 6, 21, 355, -351, -2, -40, -147, 1, 64, -62, 117, -51, -63, 69, -67, 79, -77, 79, -77, 1, 64, 2, 51, 4, -116, 1, 124, -122, 1, 129, 22, -148, 150, -148, 1, 133, -131, 118, -116, 1, 33, -31, 86, -51, -32, 38, -36, 48, -46, 48, -46, 1, 33, 2, 51, 4, -85, 1, 93, -91, 1, 98, 22, -117, 119, -117, 1, 102, 374],
  'iso-8859-3': [...e(33), 134, 434, -565, 1, r, 128, -125, 1, 136, 46, -64, 22, -135, r, 206, -203, 119, -117, 1, 1, 1, 112, -110, 1, 121, 46, -64, 22, -120, r, 191, -188, 1, 1, r, 2, 70, -2, -65, ...e(8), r, 2, 1, 1, 1, 76, -74, 1, 69, -67, 1, 1, 1, 144, -16, -125, 1, 1, 1, r, 2, 39, -2, -34, ...e(8), r, 2, 1, 1, 1, 45, -43, 1, 38, -36, 1, 1, 1, 113, -16, 380],
  'iso-8859-4': [...e(33), 100, 52, 30, -178, 132, 19, -148, 1, 184, -78, 16, 68, -185, 208, -206, 1, 85, 470, -388, -163, 117, 19, 395, -527, 169, -78, 16, 68, -29, 52, -51, -75, -63, ...e(5), 104, -34, -67, 79, -77, 75, -73, 1, 92, -26, 53, 7, -22, -98, 1, 1, 1, 1, 154, -152, 1, 1, 140, 2, -139, 34, -32, ...e(5), 73, -34, -36, 48, -46, 44, -42, 1, 61, -26, 53, 7, -22, -67, 1, 1, 1, 1, 123, -121, 1, 1, 109, 2, 366],
  'iso-8859-5': [...e(33), 865, ...e(11), -863, 865, ...e(65), 7367, -7365, ...e(11), -949, 951, 1],
  'iso-8859-6': [...e(33), r, r, r, 4, ...h(7), 1384, -1375, ...h(13), 1390, r, r, r, 4, r, 2, ...e(25), r, r, r, r, r, 6, ...e(18), ...h(13)],
  'iso-8859-7': [...e(33), 8056, 1, -8054, 8201, 3, -8201, 1, 1, 1, 721, -719, 1, 1, r, 8040, -8037, 1, 1, 1, 721, 1, 1, -719, 721, 1, 1, -719, 721, -719, 721, ...e(19), r, 2, ...e(43), r],
  'iso-8859-8': [...e(33), r, 2, ...e(7), 46, -44, ...e(14), 62, -60, 1, 1, 1, ...h(32), 8025, -6727, ...e(26), r, r, 6692, 1, r],
  'koi8-r': [9345, 2, 10, 4, 4, 4, 4, 8, 8, 8, 8, 68, 4, 4, 4, 4, 1, 1, 1, -627, 640, -903, 1, 46, 28, 1, -8645, 8833, -8817, 2, 5, 64, 9305, 1, 1, -8449, 8450, ...e(14), -8544, 8545, ...e(10), -9411, 933, -30, 1, 21, -18, 1, 15, -17, 18, -13, ...e(7), 16, -15, 1, 1, 1, -13, -4, 26, -1, -20, 17, 5, -4, -2, 3, -28, -30, 1, 21, -18, 1, 15, -17, 18, -13, ...e(7), 16, -15, 1, 1, 1, -13, -4, 26, -1, -20, 17, 5, -4, -2, 3],
  'koi8-u': [9345, 2, 10, 4, 4, 4, 4, 8, 8, 8, 8, 68, 4, 4, 4, 4, 1, 1, 1, -627, 640, -903, 1, 46, 28, 1, -8645, 8833, -8817, 2, 5, 64, 9305, 1, 1, -8449, 3, 8448, -8446, 1, 8448, 1, 1, 1, 1, -8394, -51, 8448, 1, 1, 1, -8544, 3, 8543, -8541, 1, 8543, 1, 1, 1, 1, -8410, -130, -869, 933, -30, 1, 21, -18, 1, 15, -17, 18, -13, ...e(7), 16, -15, 1, 1, 1, -13, -4, 26, -1, -20, 17, 5, -4, -2, 3, -28, -30, 1, 21, -18, 1, 15, -17, 18, -13, ...e(7), 16, -15, 1, 1, 1, -13, -4, 26, -1, -20, 17, 5, -4, -2, 3],
  'macintosh': [69, 1, 2, 2, 8, 5, 6, 5, -1, 2, 2, -1, 2, 2, 2, -1, 2, 1, 2, -1, 2, 1, 2, 2, -1, 2, 2, -1, 5, -1, 2, 1, 7972, -8048, -14, 1, 4, 8059, -8044, 41, -49, -5, 8313, -8302, -12, 8632, -8602, 18, 8518, -8557, 8627, 1, -8640, 16, 8525, 15, -2, -7759, 7787, -8577, 16, 751, -707, 18, -57, -30, 11, 8558, -8328, 8374, -66, -8539, 16, 8043, -8070, 32, 3, 18, 125, 1, 7872, 1, 8, 1, -5, 1, -7970, 9427, -9419, 121, 7884, 104, -115, 1, 56007, 1, -56033, -8042, 8035, 4, 18, -8046, 8, -9, 10, -3, 5, 1, 1, -3, 7, 1, 63531, -63533, 8, 1, -2, 88, 405, 22, -557, 553, 1, 1, -546, 549, -2, -20],
  'windows-1250': [8237, -8235, 8089, -8087, 8091, 8, -6, 1, -8089, 8104, -7888, 7897, -7903, 10, 25, -4, -233, 8072, 1, 3, 1, 5, -15, 1, -8060, 8330, -8129, 7897, -7903, 10, 25, -4, -218, 551, 17, -407, -157, 96, -94, 1, 1, 1, 181, -179, 1, 1, 1, 205, -203, 1, 554, -409, -142, 1, 1, 1, 1, 77, 90, -164, 130, 416, -415, 62, -40, -147, 1, 64, -62, 117, -51, -63, 69, -67, 79, -77, 79, -77, 1, 64, 2, 51, 4, -116, 1, 124, -122, 1, 129, 22, -148, 150, -148, 1, 133, -131, 118, -116, 1, 33, -31, 86, -51, -32, 38, -36, 48, -46, 48, -46, 1, 33, 2, 51, 4, -85, 1, 93, -91, 1, 98, 22, -117, 119, -117, 1, 102, 374],
  'windows-1251': [899, 1, 7191, -7111, 7115, 8, -6, 1, 139, -124, -7207, 7216, -7215, 2, -1, 4, 67, 7110, 1, 3, 1, 5, -15, 1, -8060, 8330, -7369, 7137, -7136, 2, -1, 4, -959, 878, 80, -86, -868, 1004, -1002, 1, 858, -856, 859, -857, 1, 1, 1, 857, -855, 1, 853, 80, 59, -988, 1, 1, 922, 7365, -7362, -921, 925, -83, 80, 2, -71, ...e(63)],
  'windows-1252': [8237, -8235, 8089, -7816, 7820, 8, -6, 1, -7515, 7530, -7888, 7897, -7911, -197, 240, -238, 1, 8072, 1, 3, 1, 5, -15, 1, -7480, 7750, -8129, 7897, -7911, -182, 225, -6],
  'windows-1253': [8237, -8235, 8089, -7816, 7820, 8, -6, 1, -8089, 8104, -8102, 8111, -8109, 1, 1, 1, 1, 8072, 1, 3, 1, 5, -15, 1, -8060, 8330, -8328, 8096, -8094, 1, 1, 1, 1, 741, 1, -739, 1, 1, 1, 1, 1, 1, r, 2, 1, 1, 1, 8039, -8037, 1, 1, 1, 721, -719, 1, 1, 721, 1, 1, -719, 721, -719, 721, ...e(19), r, 2, ...e(43), r],
  'windows-1254': [8237, -8235, 8089, -7816, 7820, 8, -6, 1, -7515, 7530, -7888, 7897, -7911, -197, 1, 1, 1, 8072, 1, 3, 1, 5, -15, 1, -7480, 7750, -8129, 7897, -7911, -182, 1, 218, -216, ...e(47), 79, -77, ...e(11), 84, 46, -127, ...e(16), 48, -46, ...e(11), 53, 46],
  'windows-1255': [8237, -8235, 8089, -7816, 7820, 8, -6, 1, -7515, 7530, -8102, 8111, -8109, 1, 1, 1, 1, 8072, 1, 3, 1, 5, -15, 1, -7480, 7750, -8328, 8096, -8094, ...e(7), 8199, -8197, 1, 1, 1, 1, 46, -44, ...e(14), 62, -60, 1, 1, 1, 1, 1265, ...e(19), 45, 1, 1, 1, 1, ...h(7), -36, ...e(26), r, r, 6692, 1, r],
  'windows-1256': [8237, -6702, 6556, -7816, 7820, 8, -6, 1, -7515, 7530, -6583, 6592, -7911, 1332, 18, -16, 39, 6505, 1, 3, 1, 5, -15, 1, -6507, 6777, -6801, 6569, -7911, 7865, 1, -6483, -1562, 1388, -1386, ...e(7), 1557, -1555, ...e(14), 1378, -1376, 1, 1, 1, 1377, 162, -160, ...e(21), -1375, 1376, 1, 1, 1, 6, 1, 1, 1, -1379, 1380, -1378, 1379, 1, 1, 1, -1377, 1, 1, 1, 1, 1374, 1, -1372, 1, 1372, 1, 1, 1, -1370, 1371, 1, -1369, 1370, -1368, 1369, -1367, 1, 7954, 1, -6461],
  'windows-1257': [8237, -8235, 8089, -8087, 8091, 8, -6, 1, -8089, 8104, -8102, 8111, -8109, 28, 543, -527, -40, 8072, 1, 3, 1, 5, -15, 1, -8060, 8330, -8328, 8096, -8094, 19, 556, -572, 1, r, 2, 1, 1, r, 2, 1, 49, -47, 173, -171, 1, 1, 1, 24, -22, ...e(5), 1, 1, 65, -63, 158, -156, 1, 1, 1, 40, 30, 42, -46, 6, -66, 1, 83, -6, -6, -67, 176, -99, 12, 20, -12, 17, 37, -29, 2, -114, 121, -119, 1, 1, 155, -49, 25, 16, -142, 159, 2, -158, 38, 42, -46, 6, -35, 1, 52, -6, -6, -36, 145, -99, 12, 20, -12, 17, 37, -29, 2, -83, 90, -88, 1, 1, 124, -49, 25, 16, -111, 128, 2, 347],
  'windows-1258': [8237, -8235, 8089, -7816, 7820, 8, -6, 1, -7515, 7530, -8102, 8111, -7911, -197, 1, 1, 1, 8072, 1, 3, 1, 5, -15, 1, -7480, 7750, -8328, 8096, -7911, -182, 1, 218, -216, ...e(34), 64, -62, ...e(7), 565, -563, 1, 1, 65, -63, 568, -566, 1, 204, -202, 1, 1, 1, 1, 1, 1, 211, 340, -548, 1, 1, 1, 33, -31, ...e(7), 534, -532, 1, 1, 34, -32, 562, -560, 1, 173, -171, 1, 1, 1, 1, 1, 1, 180, 7931],
  'windows-874': [8237, -8235, 1, 1, 1, 8098, -8096, ...e(10), 8072, 1, 3, 1, 5, -15, 1, -8060, ...e(8), 3425, ...e(57), r, r, r, r, 5, ...e(28), r, r, r, r],
  'x-mac-cyrillic': [913, ...e(31), 7153, -8048, 992, -1005, 4, 8059, -8044, 848, -856, -5, 8313, -7456, 80, 7694, -7773, 80, 7627, -8557, 8627, 1, -7695, -929, 988, -137, -4, 80, -77, 80, -78, 80, -79, 80, -2, -83, -857, 8558, -8328, 8374, -66, -8539, 16, 8043, -8070, 875, 80, -79, 80, -7, 7102, 1, 8, 1, -5, 1, -7970, 7975, -7184, 80, -79, 80, 7351, -7445, 80, -2, -31, ...e(30), 7262],
};

/* eslint-enable @stylistic/js/max-len */

/* fallback/single-byte.js + single-byte.node.js, simplified */

const l256 = { __proto__: null, length: 256 };

function getEncoding(encoding) {
  if (encoding === 'x-user-defined') {
    // https://encoding.spec.whatwg.org/#x-user-defined-decoder, 14.5.1. x-user-defined decoder
    return TypedArrayFrom(Uint16Array, l256, (_, i) => (i >= 0x80 ? 0xf700 + i : i));
  }

  if (!ObjectPrototypeHasOwnProperty(encodings, encoding)) {
    throw new ERR_ENCODING_NOT_SUPPORTED(encoding);
  }

  const map = TypedArrayFrom(Uint16Array, l256, (_, i) => i); // Unicode subset
  let prev = 127;
  map.set(TypedArrayFrom(Uint16Array, it(encodings[encoding]), (x) => (x === r ? x : (prev += x))), 128);
  return map;
}

const supported = new SafeSet(it(ObjectKeys(encodings))).add('iso-8859-8-i').add('x-user-defined');
const isSinglebyteEncoding = (enc) => supported.has(enc);

const decodersLoose = new SafeMap();
const decodersFatal = new SafeMap();

function createSinglebyteDecoder(encoding, fatal) {
  const id = encoding === 'iso-8859-8-i' ? 'iso-8859-8' : encoding;
  const decoders = fatal ? decodersFatal : decodersLoose;
  const cached = decoders.get(id);
  if (cached) return cached;

  const map = getEncoding(id);
  const incomplete = TypedArrayPrototypeIncludes(map, r);

  // Expects type-checked Buffer input
  const decoder = (buf) => {
    if (buf.byteLength === 0) return '';
    if (isAscii(buf)) return buf.latin1Slice(); // .latin1Slice is faster than .asciiSlice
    const o = new Uint16Array(buf.length);
    TypedArrayPrototypeSet(o, buf); // Copy to modify in-place, also those are 16-bit now

    let i = 0;
    for (const end7 = o.length - 7; i < end7; i += 8) {
      o[i] = map[o[i]];
      o[i + 1] = map[o[i + 1]];
      o[i + 2] = map[o[i + 2]];
      o[i + 3] = map[o[i + 3]];
      o[i + 4] = map[o[i + 4]];
      o[i + 5] = map[o[i + 5]];
      o[i + 6] = map[o[i + 6]];
      o[i + 7] = map[o[i + 7]];
    }

    for (const end = o.length; i < end; i++) o[i] = map[o[i]];

    const b = new FastBuffer(o.buffer, o.byteOffset, o.byteLength);
    if (isBigEndian) b.swap16();
    const string = b.ucs2Slice();
    if (fatal && incomplete && StringPrototypeIncludes(string, '\uFFFD')) {
      throw new ERR_ENCODING_INVALID_ENCODED_DATA(encoding, undefined);
    }
    return string;
  };

  decoders.set(id, decoder);
  return decoder;
}

module.exports = {
  isSinglebyteEncoding,
  createSinglebyteDecoder,
  getEncoding, // for tests
};