ps_uuid/methods/
from_parts_v6.rs

1use crate::UUID;
2
3// ────────────────────────────────────────────────────────────────────────────
4// v6 constructor from individual wire-format fields
5// ────────────────────────────────────────────────────────────────────────────
6
7impl UUID {
8    /// Builds an RFC-4122 *Version 6* (time-ordered) UUID from its
9    /// constituent fields.
10    ///
11    /// Timestamp layout (big-endian, network order):
12    /// - `time_high` – most-significant 32 bits of the 60-bit timestamp
13    /// - `time_mid`  – next 16 bits of the timestamp
14    /// - `time_low`  – least-significant 12 bits of the timestamp
15    ///
16    /// Remaining fields:
17    /// - `clock_seq` – 14-bit clock sequence (high-to-low order)
18    /// - `node_id`   – 48-bit node identifier (usually a MAC address)
19    ///
20    /// The function performs all bit manipulation internally, then calls
21    /// `.with_version(6)` to patch in the *version* nibble (0b0110) and
22    /// the RFC-4122 variant bits (0b10xxxxxx). It never fails.
23    #[inline]
24    #[must_use]
25    pub fn from_parts_v6(
26        time_high: u32,
27        time_mid: u16,
28        time_low: u16,
29        clock_seq: u16,
30        node_id: [u8; 6],
31    ) -> Self {
32        let mut uuid = Self::nil();
33
34        // Timestamp ---------------------------------------------------------
35        uuid.bytes[0..4].copy_from_slice(&time_high.to_be_bytes());
36        uuid.bytes[4..6].copy_from_slice(&time_mid.to_be_bytes());
37        uuid.bytes[6..8].copy_from_slice(&time_low.to_be_bytes());
38
39        // Clock sequence ----------------------------------------------------
40        uuid.bytes[8..10].copy_from_slice(&clock_seq.to_be_bytes());
41
42        // Node identifier ---------------------------------------------------
43        uuid.bytes[10..16].copy_from_slice(&node_id);
44
45        // Insert version + variant bits -------------------------------------
46        uuid.with_version(6)
47    }
48}
49
50#[cfg(test)]
51mod tests {
52    use crate::{Variant, UUID};
53
54    #[test]
55    fn builds_correct_static_example() {
56        // Timestamp: 0x0123456789abcdef
57        //   high 32 → 0x01234567
58        //   mid  16 → 0x89ab
59        //   low  12 → 0xcdef
60        // Clock-seq: 0x1234
61        // Node ID  : 00-01-02-03-04-05
62        let uuid = UUID::from_parts_v6(
63            0x0123_4567,
64            0x89ab,
65            0xcdef,
66            0x1234,
67            [0x00, 0x01, 0x02, 0x03, 0x04, 0x05],
68        );
69        let b = uuid.as_bytes();
70
71        // time_high (bytes 0-3)
72        assert_eq!(&b[0..4], &[0x01, 0x23, 0x45, 0x67]);
73        // time_mid  (bytes 4-5)
74        assert_eq!(&b[4..6], &[0x89, 0xab]);
75
76        // time_low & version (bytes 6-7)
77        // original 0xcd ef  →  version nibble patched ⇒ 0x6d ef
78        assert_eq!(b[6] & 0x0F, 0x0D);
79        assert_eq!(b[6] >> 4, 0x6);
80        assert_eq!(b[7], 0xEF);
81
82        // clock_seq & variant (bytes 8-9)
83        // original 0x12 34  →  variant patch ⇒ 0x92 34
84        assert_eq!(b[9], 0x34);
85        assert_eq!(b[8] & 0x3F, 0x12);
86        assert_eq!(b[8] >> 6, 0b10);
87
88        // node_id (bytes 10-15)
89        assert_eq!(&b[10..16], &[0x00, 0x01, 0x02, 0x03, 0x04, 0x05]);
90
91        // High-level helpers
92        assert_eq!(uuid.get_version(), Some(6));
93        assert_eq!(uuid.get_variant(), Variant::OSF);
94    }
95
96    #[test]
97    fn nil_timestamp_yields_valid_uuid() {
98        let uuid = UUID::from_parts_v6(0, 0, 0, 0, [0; 6]);
99        assert_eq!(uuid.get_version(), Some(6));
100        assert_eq!(uuid.get_variant(), Variant::OSF);
101
102        // Only version & variant bits should be non-zero.
103        let mut expected = [0u8; 16];
104        expected[6] = 0x60; // version 6 nibble
105        expected[8] = 0x80; // variant 10xxxxxx
106        assert_eq!(uuid.as_bytes(), &expected);
107    }
108
109    #[test]
110    fn byte_order_is_big_endian() {
111        let uuid = UUID::from_parts_v6(1, 1, 1, 1, [0; 6]);
112        let b = uuid.as_bytes();
113
114        // Each field must appear in network order.
115        assert_eq!(&b[0..4], &[0x00, 0x00, 0x00, 0x01]); // time_high
116        assert_eq!(&b[4..6], &[0x00, 0x01]); // time_mid
117        assert_eq!(b[6], 0x60); // version nibble
118        assert_eq!(b[7], 0x01); // low byte of time_low
119        assert_eq!(b[9], 0x01); // low byte of clock_seq
120    }
121}
ps_uuid/methods/from_parts_v6.rs

ps_uuid/methods/
from_parts_v6.rs
