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v1.js
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Mon, Feb 10, 07:06

v1.js
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import rng from './rng.js';
import stringify from './stringify.js'; // **`v1()` - Generate time-based UUID**
//
// Inspired by https://github.com/LiosK/UUID.js
// and http://docs.python.org/library/uuid.html
let _nodeId;
let _clockseq; // Previous uuid creation time
let _lastMSecs = 0;
let _lastNSecs = 0; // See https://github.com/uuidjs/uuid for API details
function v1(options, buf, offset) {
let i = buf && offset || 0;
const b = buf || new Array(16);
options = options || {};
let node = options.node || _nodeId;
let clockseq = options.clockseq !== undefined ? options.clockseq : _clockseq; // node and clockseq need to be initialized to random values if they're not
// specified. We do this lazily to minimize issues related to insufficient
// system entropy. See #189
if (node == null || clockseq == null) {
const seedBytes = options.random || (options.rng || rng)();
if (node == null) {
// Per 4.5, create and 48-bit node id, (47 random bits + multicast bit = 1)
node = _nodeId = [seedBytes[0] | 0x01, seedBytes[1], seedBytes[2], seedBytes[3], seedBytes[4], seedBytes[5]];
}
if (clockseq == null) {
// Per 4.2.2, randomize (14 bit) clockseq
clockseq = _clockseq = (seedBytes[6] << 8 | seedBytes[7]) & 0x3fff;
}
} // UUID timestamps are 100 nano-second units since the Gregorian epoch,
// (1582-10-15 00:00). JSNumbers aren't precise enough for this, so
// time is handled internally as 'msecs' (integer milliseconds) and 'nsecs'
// (100-nanoseconds offset from msecs) since unix epoch, 1970-01-01 00:00.
let msecs = options.msecs !== undefined ? options.msecs : Date.now(); // Per 4.2.1.2, use count of uuid's generated during the current clock
// cycle to simulate higher resolution clock
let nsecs = options.nsecs !== undefined ? options.nsecs : _lastNSecs + 1; // Time since last uuid creation (in msecs)
const dt = msecs - _lastMSecs + (nsecs - _lastNSecs) / 10000; // Per 4.2.1.2, Bump clockseq on clock regression
if (dt < 0 && options.clockseq === undefined) {
clockseq = clockseq + 1 & 0x3fff;
} // Reset nsecs if clock regresses (new clockseq) or we've moved onto a new
// time interval
if ((dt < 0 || msecs > _lastMSecs) && options.nsecs === undefined) {
nsecs = 0;
} // Per 4.2.1.2 Throw error if too many uuids are requested
if (nsecs >= 10000) {
throw new Error("uuid.v1(): Can't create more than 10M uuids/sec");
}
_lastMSecs = msecs;
_lastNSecs = nsecs;
_clockseq = clockseq; // Per 4.1.4 - Convert from unix epoch to Gregorian epoch
msecs += 12219292800000; // `time_low`
const tl = ((msecs & 0xfffffff) * 10000 + nsecs) % 0x100000000;
b[i++] = tl >>> 24 & 0xff;
b[i++] = tl >>> 16 & 0xff;
b[i++] = tl >>> 8 & 0xff;
b[i++] = tl & 0xff; // `time_mid`
const tmh = msecs / 0x100000000 * 10000 & 0xfffffff;
b[i++] = tmh >>> 8 & 0xff;
b[i++] = tmh & 0xff; // `time_high_and_version`
b[i++] = tmh >>> 24 & 0xf | 0x10; // include version
b[i++] = tmh >>> 16 & 0xff; // `clock_seq_hi_and_reserved` (Per 4.2.2 - include variant)
b[i++] = clockseq >>> 8 | 0x80; // `clock_seq_low`
b[i++] = clockseq & 0xff; // `node`
for (let n = 0; n < 6; ++n) {
b[i + n] = node[n];
}
return buf || stringify(b);
}
export default v1;

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