1 | import rng from './rng.js';
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2 | import stringify from './stringify.js'; // **`v1()` - Generate time-based UUID**
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3 | //
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4 | // Inspired by https://github.com/LiosK/UUID.js
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5 | // and http://docs.python.org/library/uuid.html
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6 |
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7 | let _nodeId;
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8 |
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9 | let _clockseq; // Previous uuid creation time
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10 |
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11 |
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12 | let _lastMSecs = 0;
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13 | let _lastNSecs = 0; // See https://github.com/uuidjs/uuid for API details
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14 |
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15 | function v1(options, buf, offset) {
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16 | let i = buf && offset || 0;
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17 | const b = buf || new Array(16);
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18 | options = options || {};
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19 | let node = options.node || _nodeId;
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20 | let clockseq = options.clockseq !== undefined ? options.clockseq : _clockseq; // node and clockseq need to be initialized to random values if they're not
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21 | // specified. We do this lazily to minimize issues related to insufficient
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22 | // system entropy. See #189
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23 |
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24 | if (node == null || clockseq == null) {
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25 | const seedBytes = options.random || (options.rng || rng)();
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26 |
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27 | if (node == null) {
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28 | // Per 4.5, create and 48-bit node id, (47 random bits + multicast bit = 1)
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29 | node = _nodeId = [seedBytes[0] | 0x01, seedBytes[1], seedBytes[2], seedBytes[3], seedBytes[4], seedBytes[5]];
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30 | }
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31 |
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32 | if (clockseq == null) {
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33 | // Per 4.2.2, randomize (14 bit) clockseq
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34 | clockseq = _clockseq = (seedBytes[6] << 8 | seedBytes[7]) & 0x3fff;
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35 | }
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36 | } // UUID timestamps are 100 nano-second units since the Gregorian epoch,
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37 | // (1582-10-15 00:00). JSNumbers aren't precise enough for this, so
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38 | // time is handled internally as 'msecs' (integer milliseconds) and 'nsecs'
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39 | // (100-nanoseconds offset from msecs) since unix epoch, 1970-01-01 00:00.
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40 |
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41 |
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42 | let msecs = options.msecs !== undefined ? options.msecs : Date.now(); // Per 4.2.1.2, use count of uuid's generated during the current clock
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43 | // cycle to simulate higher resolution clock
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44 |
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45 | let nsecs = options.nsecs !== undefined ? options.nsecs : _lastNSecs + 1; // Time since last uuid creation (in msecs)
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46 |
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47 | const dt = msecs - _lastMSecs + (nsecs - _lastNSecs) / 10000; // Per 4.2.1.2, Bump clockseq on clock regression
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48 |
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49 | if (dt < 0 && options.clockseq === undefined) {
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50 | clockseq = clockseq + 1 & 0x3fff;
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51 | } // Reset nsecs if clock regresses (new clockseq) or we've moved onto a new
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52 | // time interval
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53 |
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54 |
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55 | if ((dt < 0 || msecs > _lastMSecs) && options.nsecs === undefined) {
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56 | nsecs = 0;
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57 | } // Per 4.2.1.2 Throw error if too many uuids are requested
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58 |
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59 |
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60 | if (nsecs >= 10000) {
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61 | throw new Error("uuid.v1(): Can't create more than 10M uuids/sec");
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62 | }
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63 |
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64 | _lastMSecs = msecs;
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65 | _lastNSecs = nsecs;
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66 | _clockseq = clockseq; // Per 4.1.4 - Convert from unix epoch to Gregorian epoch
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67 |
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68 | msecs += 12219292800000; // `time_low`
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69 |
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70 | const tl = ((msecs & 0xfffffff) * 10000 + nsecs) % 0x100000000;
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71 | b[i++] = tl >>> 24 & 0xff;
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72 | b[i++] = tl >>> 16 & 0xff;
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73 | b[i++] = tl >>> 8 & 0xff;
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74 | b[i++] = tl & 0xff; // `time_mid`
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75 |
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76 | const tmh = msecs / 0x100000000 * 10000 & 0xfffffff;
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77 | b[i++] = tmh >>> 8 & 0xff;
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78 | b[i++] = tmh & 0xff; // `time_high_and_version`
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79 |
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80 | b[i++] = tmh >>> 24 & 0xf | 0x10; // include version
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81 |
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82 | b[i++] = tmh >>> 16 & 0xff; // `clock_seq_hi_and_reserved` (Per 4.2.2 - include variant)
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83 |
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84 | b[i++] = clockseq >>> 8 | 0x80; // `clock_seq_low`
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85 |
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86 | b[i++] = clockseq & 0xff; // `node`
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87 |
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88 | for (let n = 0; n < 6; ++n) {
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89 | b[i + n] = node[n];
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90 | }
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91 |
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92 | return buf || stringify(b);
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93 | }
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94 |
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95 | export default v1; |
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