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
160
161
162
163

// This is a part of Chrono.
// See README.md and LICENSE.txt for details.

//! ISO 8601 week.

use core::fmt;

use super::internals::{DateImpl, Of, YearFlags};

/// ISO 8601 week.
///
/// This type, combined with [`Weekday`](../enum.Weekday.html),
/// constitues the ISO 8601 [week date](./struct.NaiveDate.html#week-date).
/// One can retrieve this type from the existing [`Datelike`](../trait.Datelike.html) types
/// via the [`Datelike::iso_week`](../trait.Datelike.html#tymethod.iso_week) method.
#[derive(PartialEq, Eq, PartialOrd, Ord, Copy, Clone)]
pub struct IsoWeek {
    // note that this allows for larger year range than `NaiveDate`.
    // this is crucial because we have an edge case for the first and last week supported,
    // which year number might not match the calendar year number.
    ywf: DateImpl, // (year << 10) | (week << 4) | flag
}

/// Returns the corresponding `IsoWeek` from the year and the `Of` internal value.
//
// internal use only. we don't expose the public constructor for `IsoWeek` for now,
// because the year range for the week date and the calendar date do not match and
// it is confusing to have a date that is out of range in one and not in another.
// currently we sidestep this issue by making `IsoWeek` fully dependent of `Datelike`.
pub fn iso_week_from_yof(year: i32, of: Of) -> IsoWeek {
    let (rawweek, _) = of.isoweekdate_raw();
    let (year, week) = if rawweek < 1 {
        // previous year
        let prevlastweek = YearFlags::from_year(year - 1).nisoweeks();
        (year - 1, prevlastweek)
    } else {
        let lastweek = of.flags().nisoweeks();
        if rawweek > lastweek {
            // next year
            (year + 1, 1)
        } else {
            (year, rawweek)
        }
    };
    IsoWeek { ywf: (year << 10) | (week << 4) as DateImpl | DateImpl::from(of.flags().0) }
}

impl IsoWeek {
    /// Returns the year number for this ISO week.
    ///
    /// # Example
    ///
    /// ~~~~
    /// use chrono::{NaiveDate, Datelike, Weekday};
    ///
    /// let d = NaiveDate::from_isoywd(2015, 1, Weekday::Mon);
    /// assert_eq!(d.iso_week().year(), 2015);
    /// ~~~~
    ///
    /// This year number might not match the calendar year number.
    /// Continuing the example...
    ///
    /// ~~~~
    /// # use chrono::{NaiveDate, Datelike, Weekday};
    /// # let d = NaiveDate::from_isoywd(2015, 1, Weekday::Mon);
    /// assert_eq!(d.year(), 2014);
    /// assert_eq!(d, NaiveDate::from_ymd(2014, 12, 29));
    /// ~~~~
    #[inline]
    pub fn year(&self) -> i32 {
        self.ywf >> 10
    }

    /// Returns the ISO week number starting from 1.
    ///
    /// The return value ranges from 1 to 53. (The last week of year differs by years.)
    ///
    /// # Example
    ///
    /// ~~~~
    /// use chrono::{NaiveDate, Datelike, Weekday};
    ///
    /// let d = NaiveDate::from_isoywd(2015, 15, Weekday::Mon);
    /// assert_eq!(d.iso_week().week(), 15);
    /// ~~~~
    #[inline]
    pub fn week(&self) -> u32 {
        ((self.ywf >> 4) & 0x3f) as u32
    }

    /// Returns the ISO week number starting from 0.
    ///
    /// The return value ranges from 0 to 52. (The last week of year differs by years.)
    ///
    /// # Example
    ///
    /// ~~~~
    /// use chrono::{NaiveDate, Datelike, Weekday};
    ///
    /// let d = NaiveDate::from_isoywd(2015, 15, Weekday::Mon);
    /// assert_eq!(d.iso_week().week0(), 14);
    /// ~~~~
    #[inline]
    pub fn week0(&self) -> u32 {
        ((self.ywf >> 4) & 0x3f) as u32 - 1
    }
}

/// The `Debug` output of the ISO week `w` is the same as
/// [`d.format("%G-W%V")`](../format/strftime/index.html)
/// where `d` is any `NaiveDate` value in that week.
///
/// # Example
///
/// ~~~~
/// use chrono::{NaiveDate, Datelike};
///
/// assert_eq!(format!("{:?}", NaiveDate::from_ymd(2015,  9,  5).iso_week()), "2015-W36");
/// assert_eq!(format!("{:?}", NaiveDate::from_ymd(   0,  1,  3).iso_week()), "0000-W01");
/// assert_eq!(format!("{:?}", NaiveDate::from_ymd(9999, 12, 31).iso_week()), "9999-W52");
/// ~~~~
///
/// ISO 8601 requires an explicit sign for years before 1 BCE or after 9999 CE.
///
/// ~~~~
/// # use chrono::{NaiveDate, Datelike};
/// assert_eq!(format!("{:?}", NaiveDate::from_ymd(    0,  1,  2).iso_week()),  "-0001-W52");
/// assert_eq!(format!("{:?}", NaiveDate::from_ymd(10000, 12, 31).iso_week()), "+10000-W52");
/// ~~~~
impl fmt::Debug for IsoWeek {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let year = self.year();
        let week = self.week();
        if 0 <= year && year <= 9999 {
            write!(f, "{:04}-W{:02}", year, week)
        } else {
            // ISO 8601 requires the explicit sign for out-of-range years
            write!(f, "{:+05}-W{:02}", year, week)
        }
    }
}

#[cfg(test)]
mod tests {
    use naive::{internals, MAX_DATE, MIN_DATE};
    use Datelike;

    #[test]
    fn test_iso_week_extremes() {
        let minweek = MIN_DATE.iso_week();
        let maxweek = MAX_DATE.iso_week();

        assert_eq!(minweek.year(), internals::MIN_YEAR);
        assert_eq!(minweek.week(), 1);
        assert_eq!(minweek.week0(), 0);
        assert_eq!(format!("{:?}", minweek), MIN_DATE.format("%G-W%V").to_string());

        assert_eq!(maxweek.year(), internals::MAX_YEAR + 1);
        assert_eq!(maxweek.week(), 1);
        assert_eq!(maxweek.week0(), 0);
        assert_eq!(format!("{:?}", maxweek), MAX_DATE.format("%G-W%V").to_string());
    }
}