diff options
Diffstat (limited to 'vanilla/node_modules/@exodus/bytes/fallback/encoding.util.js')
| -rw-r--r-- | vanilla/node_modules/@exodus/bytes/fallback/encoding.util.js | 64 |
1 files changed, 0 insertions, 64 deletions
diff --git a/vanilla/node_modules/@exodus/bytes/fallback/encoding.util.js b/vanilla/node_modules/@exodus/bytes/fallback/encoding.util.js deleted file mode 100644 index a53cefb..0000000 --- a/vanilla/node_modules/@exodus/bytes/fallback/encoding.util.js +++ /dev/null @@ -1,64 +0,0 @@ -// Get a number of last bytes in an Uint8Array `u` ending at `len` that don't -// form a codepoint yet, but can be a part of a single codepoint on more data -export function unfinishedBytes(u, len, enc) { - switch (enc) { - case 'utf-8': { - // 0-3 - let p = 0 - while (p < 2 && p < len && (u[len - p - 1] & 0xc0) === 0x80) p++ // go back 0-2 trailing bytes - if (p === len) return 0 // no space for lead - const l = u[len - p - 1] - if (l < 0xc2 || l > 0xf4) return 0 // not a lead - if (p === 0) return 1 // nothing to recheck, we have only lead, return it. 2-byte must return here - if (l < 0xe0 || (l < 0xf0 && p >= 2)) return 0 // 2-byte, or 3-byte or less and we already have 2 trailing - const lower = l === 0xf0 ? 0x90 : l === 0xe0 ? 0xa0 : 0x80 - const upper = l === 0xf4 ? 0x8f : l === 0xed ? 0x9f : 0xbf - const n = u[len - p] - return n >= lower && n <= upper ? p + 1 : 0 - } - - case 'utf-16le': - case 'utf-16be': { - // 0-3 - const p = len % 2 // uneven byte length adds 1 - if (len < 2) return p - const l = len - p - 1 - const last = enc === 'utf-16le' ? (u[l] << 8) ^ u[l - 1] : (u[l - 1] << 8) ^ u[l] - return last >= 0xd8_00 && last < 0xdc_00 ? p + 2 : p // lone lead adds 2 - } - } - - throw new Error('Unsupported encoding') -} - -// Merge prefix `chunk` with `u` and return new combined prefix -// For u.length < 3, fully consumes u and can return unfinished data, -// otherwise returns a prefix with no unfinished bytes -export function mergePrefix(u, chunk, enc) { - if (u.length === 0) return chunk - if (u.length < 3) { - // No reason to bruteforce offsets, also it's possible this doesn't yet end the sequence - const a = new Uint8Array(u.length + chunk.length) - a.set(chunk) - a.set(u, chunk.length) - return a - } - - // Slice off a small portion of u into prefix chunk so we can decode them separately without extending array size - const t = new Uint8Array(chunk.length + 3) // We have 1-3 bytes and need 1-3 more bytes - t.set(chunk) - t.set(u.subarray(0, 3), chunk.length) - - // Stop at the first offset where unfinished bytes reaches 0 or fits into u - // If that doesn't happen (u too short), just concat chunk and u completely (above) - for (let i = 1; i <= 3; i++) { - const unfinished = unfinishedBytes(t, chunk.length + i, enc) // 0-3 - if (unfinished <= i) { - // Always reachable at 3, but we still need 'unfinished' value for it - const add = i - unfinished // 0-3 - return add > 0 ? t.subarray(0, chunk.length + add) : chunk - } - } - - // Unreachable -} |
