bdays 0.1.4

Business Days calendars for Rustaceans.
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
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159


use ::chrono::{Datelike, Weekday, NaiveDate, Duration};
use crate::HolidayCalendar;

/// United States federal holidays.
pub struct USSettlement;

fn end_of_month(mut yy: i32, mut mm: u32) -> NaiveDate {
    assert!(mm <= 12);

    if mm == 12 {
        yy += 1;
        mm = 1;
    } else {
        mm += 1;
    }

    NaiveDate::from_ymd_opt(yy, mm, 1).expect("Valid date").pred_opt().unwrap()
}

#[test]
fn test_end_of_month() {
    assert_eq!( end_of_month(2018, 11), NaiveDate::from_ymd_opt(2018, 11, 30).expect("Valid date") );
    assert_eq!( end_of_month(2018, 12), NaiveDate::from_ymd_opt(2018, 12, 31).expect("Valid date") );
    assert_eq!( end_of_month(2019,  1), NaiveDate::from_ymd_opt(2019,  1, 31).expect("Valid date") );
}

fn find_weekday_ascending(weekday: Weekday, yy: i32, mm: u32, occurrence: u32) -> NaiveDate {
    let anchor = NaiveDate::from_ymd_opt(yy, mm, 1).expect("Valid date");
    let mut offset = (weekday.number_from_monday() + 7 - anchor.weekday().number_from_monday()) % 7;

    if occurrence > 1 {
        offset += 7 * (occurrence - 1);
    }

    anchor + Duration::days(offset as i64)
}

fn find_weekday_descending(weekday: Weekday, yy: i32, mm: u32, occurrence: u32) -> NaiveDate {
    let anchor = end_of_month(yy, mm);
    let mut offset = (anchor.weekday().number_from_monday() + 7 - weekday.number_from_monday()) % 7;

    if occurrence > 1 {
        offset += 7 * (occurrence - 1);
    }

    anchor - Duration::days(offset as i64)
}

fn find_weekday(weekday: Weekday, yy: i32, mm: u32, occurrence: u32, ascending: bool) -> NaiveDate {
    if ascending {
        find_weekday_ascending(weekday, yy, mm, occurrence)
    } else {
        find_weekday_descending(weekday, yy, mm, occurrence)
    }
}

#[test]
fn test_find_weekday() {
    assert_eq!(find_weekday(Weekday::Mon, 2015, 07, 1, true), NaiveDate::from_ymd_opt(2015, 07, 06).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Mon, 2015, 07, 2, true), NaiveDate::from_ymd_opt(2015, 07, 13).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Mon, 2015, 07, 3, true), NaiveDate::from_ymd_opt(2015, 07, 20).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Mon, 2015, 07, 4, true), NaiveDate::from_ymd_opt(2015, 07, 27).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Mon, 2015, 07, 5, true), NaiveDate::from_ymd_opt(2015, 08, 03).expect("Valid date"));

    assert_eq!(find_weekday(Weekday::Mon, 2015, 07, 1, false), NaiveDate::from_ymd_opt(2015, 07, 27).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Mon, 2015, 07, 2, false), NaiveDate::from_ymd_opt(2015, 07, 20).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Mon, 2015, 07, 3, false), NaiveDate::from_ymd_opt(2015, 07, 13).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Mon, 2015, 07, 4, false), NaiveDate::from_ymd_opt(2015, 07, 06).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Mon, 2015, 07, 5, false), NaiveDate::from_ymd_opt(2015, 06, 29).expect("Valid date"));

    assert_eq!(find_weekday(Weekday::Fri, 2015, 07, 1, true), NaiveDate::from_ymd_opt(2015, 07, 03).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Fri, 2015, 07, 2, true), NaiveDate::from_ymd_opt(2015, 07, 10).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Fri, 2015, 07, 3, true), NaiveDate::from_ymd_opt(2015, 07, 17).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Fri, 2015, 07, 4, true), NaiveDate::from_ymd_opt(2015, 07, 24).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Fri, 2015, 07, 5, true), NaiveDate::from_ymd_opt(2015, 07, 31).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Fri, 2015, 07, 6, true), NaiveDate::from_ymd_opt(2015, 08, 07).expect("Valid date"));

    assert_eq!(find_weekday(Weekday::Fri, 2015, 07, 1, false), NaiveDate::from_ymd_opt(2015, 07, 31).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Fri, 2015, 07, 2, false), NaiveDate::from_ymd_opt(2015, 07, 24).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Fri, 2015, 07, 3, false), NaiveDate::from_ymd_opt(2015, 07, 17).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Fri, 2015, 07, 4, false), NaiveDate::from_ymd_opt(2015, 07, 10).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Fri, 2015, 07, 5, false), NaiveDate::from_ymd_opt(2015, 07, 03).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Fri, 2015, 07, 6, false), NaiveDate::from_ymd_opt(2015, 06, 26).expect("Valid date"));

    assert_eq!(find_weekday(Weekday::Wed, 2015, 07, 1, true) , NaiveDate::from_ymd_opt(2015, 07, 01).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Wed, 2015, 07, 2, true) , NaiveDate::from_ymd_opt(2015, 07, 08).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Wed, 2015, 07, 3, true) , NaiveDate::from_ymd_opt(2015, 07, 15).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Wed, 2015, 07, 4, true) , NaiveDate::from_ymd_opt(2015, 07, 22).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Wed, 2015, 07, 5, true) , NaiveDate::from_ymd_opt(2015, 07, 29).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Wed, 2015, 07, 6, true) , NaiveDate::from_ymd_opt(2015, 08, 05).expect("Valid date"));

    assert_eq!(find_weekday(Weekday::Wed, 2015, 07, 1, false) , NaiveDate::from_ymd_opt(2015, 07, 29).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Wed, 2015, 07, 2, false) , NaiveDate::from_ymd_opt(2015, 07, 22).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Wed, 2015, 07, 3, false) , NaiveDate::from_ymd_opt(2015, 07, 15).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Wed, 2015, 07, 4, false) , NaiveDate::from_ymd_opt(2015, 07, 08).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Wed, 2015, 07, 5, false) , NaiveDate::from_ymd_opt(2015, 07, 01).expect("Valid date"));
    assert_eq!(find_weekday(Weekday::Wed, 2015, 07, 6, false) , NaiveDate::from_ymd_opt(2015, 06, 24).expect("Valid date"));
}

/// In the United States, if a holiday falls on Saturday, it's observed on the preceding Friday.
/// If it falls on Sunday, it's observed on the next Monday.
fn adjust_weekend_holidays_us(date: NaiveDate) -> NaiveDate {
    match date.weekday() {
        Weekday::Sat => date - Duration::days(1),
        Weekday::Sun => date + Duration::days(1),
        _ => date
    }
}

impl<T: Datelike + Copy + PartialOrd> HolidayCalendar<T> for USSettlement {

    fn is_holiday(&self, date: T) -> bool {
        let (yy, mm, dd) = (date.year(), date.month(), date.day());
        let dt_naive = NaiveDate::from_ymd_opt(yy, mm, dd).expect("Valid date");

        if
            // New Year's Day
            adjust_weekend_holidays_us(NaiveDate::from_ymd_opt(yy, 1, 1).expect("Valid date")) == dt_naive
            ||
            // New Year's Day on the previous year when 1st Jan is Saturday
            (mm == 12 && dd == 31 && dt_naive.weekday() == Weekday::Fri)
            ||
            // Birthday of Martin Luther King, Jr.
            (yy >= 1983 && adjust_weekend_holidays_us(find_weekday(Weekday::Mon, yy, 1, 3, true)) == dt_naive)
            ||
            // Washington's Birthday
            adjust_weekend_holidays_us(find_weekday(Weekday::Mon, yy, 2, 3, true)) == dt_naive
            ||
            // Memorial Day
            adjust_weekend_holidays_us(find_weekday(Weekday::Mon, yy, 5, 1, false)) == dt_naive
            ||
            // Juneteenth
            (yy >= 2021 && adjust_weekend_holidays_us(NaiveDate::from_ymd_opt(yy, 6, 19).expect("Valid date")) == dt_naive )
            ||
            // Independence Day
            adjust_weekend_holidays_us(NaiveDate::from_ymd_opt(yy, 7, 4).expect("Valid date")) == dt_naive
            ||
            // Labor Day
            adjust_weekend_holidays_us(find_weekday(Weekday::Mon, yy, 9, 1, true)) == dt_naive
            ||
            // Columbus Day
            adjust_weekend_holidays_us(find_weekday(Weekday::Mon, yy, 10, 2, true)) == dt_naive
            ||
            // Veterans Day
            adjust_weekend_holidays_us(NaiveDate::from_ymd_opt(yy, 11, 11).expect("Valid date")) == dt_naive
            ||
            // Thanksgiving Day
            adjust_weekend_holidays_us(find_weekday(Weekday::Thu, yy, 11, 4, true)) == dt_naive
            ||
            // Christmas
            adjust_weekend_holidays_us(NaiveDate::from_ymd_opt(yy, 12, 25).expect("Valid date")) == dt_naive
         {
            return true
        }

        false
    }
}