iztro 0.1.0

Strongly typed Zi Wei Dou Shu chart generation aligned with iztro.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129

use super::formulas::{
    jie_lu_branch, kong_wang_branch, tian_chu_branch, tian_fu_adj_branch, tian_guan_branch,
    xian_chi_branch, xun_kong_branch,
};
use lunar_lite::{EARTHLY_BRANCHES, EarthlyBranch, HEAVENLY_STEMS, HeavenlyStem};

// Tables transcribed from iztro 2.5.8 `getYearlyStarIndex` /
// `getHuagaiXianchiIndex` and cross-checked against `astro.byLunar` output.

/// 咸池, by birth year branch (子..亥). Same 三合 family as 华盖.
#[test]
fn xian_chi_matches_iztro_branch_table() {
    use EarthlyBranch::*;
    let expected = [You, Wu, Mao, Zi, You, Wu, Mao, Zi, You, Wu, Mao, Zi];
    for (index, branch) in EARTHLY_BRANCHES.into_iter().enumerate() {
        assert_eq!(
            xian_chi_branch(branch),
            expected[index],
            "咸池 for {branch:?}"
        );
    }
}

/// 天空 sits one branch forward from the birth year branch.
#[test]
fn tian_kong_is_one_branch_after_year_branch() {
    for branch in EARTHLY_BRANCHES {
        assert_eq!(
            branch.offset(1),
            EarthlyBranch::from_index(branch.index() + 1)
        );
    }
}

/// 天官, by birth year stem (甲..癸).
#[test]
fn tian_guan_matches_iztro_stem_table() {
    use EarthlyBranch::*;
    let expected = [Wei, Chen, Si, Yin, Mao, You, Hai, You, Xu, Wu];
    for (index, stem) in HEAVENLY_STEMS.into_iter().enumerate() {
        assert_eq!(tian_guan_branch(stem), expected[index], "天官 for {stem:?}");
    }
}

/// 天厨, by birth year stem (甲..癸).
#[test]
fn tian_chu_matches_iztro_stem_table() {
    use EarthlyBranch::*;
    let expected = [Si, Wu, Zi, Si, Wu, Shen, Yin, Wu, You, Hai];
    for (index, stem) in HEAVENLY_STEMS.into_iter().enumerate() {
        assert_eq!(tian_chu_branch(stem), expected[index], "天厨 for {stem:?}");
    }
}

/// 天福 adjective star, by birth year stem (甲..癸).
#[test]
fn tian_fu_adj_matches_iztro_stem_table() {
    use EarthlyBranch::*;
    let expected = [You, Shen, Zi, Hai, Mao, Yin, Wu, Si, Wu, Si];
    for (index, stem) in HEAVENLY_STEMS.into_iter().enumerate() {
        assert_eq!(
            tian_fu_adj_branch(stem),
            expected[index],
            "天福 for {stem:?}"
        );
    }
}

/// 截路 / 空亡, by birth year stem pair (stem index mod 5). 空亡 is one
/// branch forward from 截路.
#[test]
fn jie_lu_and_kong_wang_match_iztro_stem_table() {
    use EarthlyBranch::*;
    let jie_lu = [Shen, Wu, Chen, Yin, Zi, Shen, Wu, Chen, Yin, Zi];
    let kong_wang = [You, Wei, Si, Mao, Chou, You, Wei, Si, Mao, Chou];
    for (index, stem) in HEAVENLY_STEMS.into_iter().enumerate() {
        assert_eq!(jie_lu_branch(stem), jie_lu[index], "截路 for {stem:?}");
        assert_eq!(
            kong_wang_branch(stem),
            kong_wang[index],
            "空亡 for {stem:?}"
        );
        assert_eq!(
            kong_wang_branch(stem),
            jie_lu_branch(stem).offset(1),
            "空亡 should follow 截路 for {stem:?}"
        );
    }
}

/// 旬空 (旬中空亡) across the full sexagenary cycle: the void branch of the
/// year's 甲-旬 whose 阴阳 polarity matches the year branch.
#[test]
fn xun_kong_matches_iztro_over_full_sexagenary_cycle() {
    use EarthlyBranch::*;
    // i = sexagenary position; stem = i % 10, branch = i % 12.
    let expected = [
        Xu, Hai, Xu, Hai, Xu, Hai, Xu, Hai, Xu, Hai, // 甲子旬: void 戌亥
        Shen, You, Shen, You, Shen, You, Shen, You, Shen, You, // 甲戌旬: void 申酉
        Wu, Wei, Wu, Wei, Wu, Wei, Wu, Wei, Wu, Wei, // 甲申旬: void 午未
        Chen, Si, Chen, Si, Chen, Si, Chen, Si, Chen, Si, // 甲午旬: void 辰巳
        Yin, Mao, Yin, Mao, Yin, Mao, Yin, Mao, Yin, Mao, // 甲辰旬: void 寅卯
        Zi, Chou, Zi, Chou, Zi, Chou, Zi, Chou, Zi, Chou, // 甲寅旬: void 子丑
    ];
    for (i, &want) in expected.iter().enumerate() {
        let stem = HeavenlyStem::from_index(i % 10);
        let branch = EarthlyBranch::from_index(i % 12);
        assert_eq!(
            xun_kong_branch(stem, branch),
            want,
            "旬空 for sexagenary position {i} ({stem:?}{branch:?})"
        );
    }
}

/// The 旬空 result always shares the birth year branch's 阴阳 polarity.
#[test]
fn xun_kong_polarity_matches_year_branch() {
    for i in 0..60usize {
        let stem = HeavenlyStem::from_index(i % 10);
        let branch = EarthlyBranch::from_index(i % 12);
        let void = xun_kong_branch(stem, branch);
        assert_eq!(
            void.index() % 2,
            branch.index() % 2,
            "旬空 polarity mismatch for {stem:?}{branch:?}"
        );
    }
}