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perf: removed unnecessary offset and byteToHex calc #675

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perf: removed unnecessary offset and byteToHex calc #675

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312 changes: 312 additions & 0 deletions src/stringify-internal.js
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@@ -0,0 +1,312 @@
/**
* This is the internal `stringify()` function used by the library.
* It isn't exposed in the index because it assumes no offset.
*/

import validate from './validate.js';

/**
* Convert array of 16 byte values to UUID string format of the form:
* XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
*/
const byteToHex = [
'00',
'01',
'02',
'03',
'04',
'05',
'06',
'07',
'08',
'09',
'0a',
'0b',
'0c',
'0d',
'0e',
'0f',
'10',
'11',
'12',
'13',
'14',
'15',
'16',
'17',
'18',
'19',
'1a',
'1b',
'1c',
'1d',
'1e',
'1f',
'20',
'21',
'22',
'23',
'24',
'25',
'26',
'27',
'28',
'29',
'2a',
'2b',
'2c',
'2d',
'2e',
'2f',
'30',
'31',
'32',
'33',
'34',
'35',
'36',
'37',
'38',
'39',
'3a',
'3b',
'3c',
'3d',
'3e',
'3f',
'40',
'41',
'42',
'43',
'44',
'45',
'46',
'47',
'48',
'49',
'4a',
'4b',
'4c',
'4d',
'4e',
'4f',
'50',
'51',
'52',
'53',
'54',
'55',
'56',
'57',
'58',
'59',
'5a',
'5b',
'5c',
'5d',
'5e',
'5f',
'60',
'61',
'62',
'63',
'64',
'65',
'66',
'67',
'68',
'69',
'6a',
'6b',
'6c',
'6d',
'6e',
'6f',
'70',
'71',
'72',
'73',
'74',
'75',
'76',
'77',
'78',
'79',
'7a',
'7b',
'7c',
'7d',
'7e',
'7f',
'80',
'81',
'82',
'83',
'84',
'85',
'86',
'87',
'88',
'89',
'8a',
'8b',
'8c',
'8d',
'8e',
'8f',
'90',
'91',
'92',
'93',
'94',
'95',
'96',
'97',
'98',
'99',
'9a',
'9b',
'9c',
'9d',
'9e',
'9f',
'a0',
'a1',
'a2',
'a3',
'a4',
'a5',
'a6',
'a7',
'a8',
'a9',
'aa',
'ab',
'ac',
'ad',
'ae',
'af',
'b0',
'b1',
'b2',
'b3',
'b4',
'b5',
'b6',
'b7',
'b8',
'b9',
'ba',
'bb',
'bc',
'bd',
'be',
'bf',
'c0',
'c1',
'c2',
'c3',
'c4',
'c5',
'c6',
'c7',
'c8',
'c9',
'ca',
'cb',
'cc',
'cd',
'ce',
'cf',
'd0',
'd1',
'd2',
'd3',
'd4',
'd5',
'd6',
'd7',
'd8',
'd9',
'da',
'db',
'dc',
'dd',
'de',
'df',
'e0',
'e1',
'e2',
'e3',
'e4',
'e5',
'e6',
'e7',
'e8',
'e9',
'ea',
'eb',
'ec',
'ed',
'ee',
'ef',
'f0',
'f1',
'f2',
'f3',
'f4',
'f5',
'f6',
'f7',
'f8',
'f9',
'fa',
'fb',
'fc',
'fd',
'fe',
'ff',
];

export function unsafeStringify(arr) {
// Note: Be careful editing this code! It's been tuned for performance
// and works in ways you may not expect. See https://github.com/uuidjs/uuid/pull/434
return (
byteToHex[arr[0]] +
byteToHex[arr[1]] +
byteToHex[arr[2]] +
byteToHex[arr[3]] +
'-' +
byteToHex[arr[4]] +
byteToHex[arr[5]] +
'-' +
byteToHex[arr[6]] +
byteToHex[arr[7]] +
'-' +
byteToHex[arr[8]] +
byteToHex[arr[9]] +
'-' +
byteToHex[arr[10]] +
byteToHex[arr[11]] +
byteToHex[arr[12]] +
byteToHex[arr[13]] +
byteToHex[arr[14]] +
byteToHex[arr[15]]
).toLowerCase();
}

function stringify(arr) {
const uuid = unsafeStringify(arr);
// Consistency check for valid UUID. If this throws, it's likely due to one
// of the following:
// - One or more input array values don't map to a hex octet (leading to
// "undefined" in the uuid)
// - Invalid input values for the RFC `version` or `variant` fields
if (!validate(uuid)) {
throw TypeError('Stringified UUID is invalid');
}

return uuid;
}

export default stringify;