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
164
165
166
167
168
169
170
//! Days of the week.

use core::fmt::{self, Display};
use core::str::FromStr;

use Weekday::*;

use crate::error;

/// Days of the week.
///
/// As order is dependent on context (Sunday could be either two days after or five days before
/// Friday), this type does not implement `PartialOrd` or `Ord`.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum Weekday {
    #[allow(clippy::missing_docs_in_private_items)]
    Monday,
    #[allow(clippy::missing_docs_in_private_items)]
    Tuesday,
    #[allow(clippy::missing_docs_in_private_items)]
    Wednesday,
    #[allow(clippy::missing_docs_in_private_items)]
    Thursday,
    #[allow(clippy::missing_docs_in_private_items)]
    Friday,
    #[allow(clippy::missing_docs_in_private_items)]
    Saturday,
    #[allow(clippy::missing_docs_in_private_items)]
    Sunday,
}

impl Weekday {
    /// Get the previous weekday.
    ///
    /// ```rust
    /// # use time::Weekday;
    /// assert_eq!(Weekday::Tuesday.previous(), Weekday::Monday);
    /// ```
    pub const fn previous(self) -> Self {
        match self {
            Monday => Sunday,
            Tuesday => Monday,
            Wednesday => Tuesday,
            Thursday => Wednesday,
            Friday => Thursday,
            Saturday => Friday,
            Sunday => Saturday,
        }
    }

    /// Get the next weekday.
    ///
    /// ```rust
    /// # use time::Weekday;
    /// assert_eq!(Weekday::Monday.next(), Weekday::Tuesday);
    /// ```
    pub const fn next(self) -> Self {
        match self {
            Monday => Tuesday,
            Tuesday => Wednesday,
            Wednesday => Thursday,
            Thursday => Friday,
            Friday => Saturday,
            Saturday => Sunday,
            Sunday => Monday,
        }
    }

    /// Get n-th next day.
    ///
    /// ```rust
    /// # use time::Weekday;
    /// assert_eq!(Weekday::Monday.nth_next(1), Weekday::Tuesday);
    /// assert_eq!(Weekday::Sunday.nth_next(10), Weekday::Wednesday);
    /// ```
    pub const fn nth_next(self, n: u8) -> Self {
        match (self.number_days_from_monday() + n % 7) % 7 {
            0 => Monday,
            1 => Tuesday,
            2 => Wednesday,
            3 => Thursday,
            4 => Friday,
            5 => Saturday,
            val => {
                debug_assert!(val == 6);
                Sunday
            }
        }
    }

    /// Get the one-indexed number of days from Monday.
    ///
    /// ```rust
    /// # use time::Weekday;
    /// assert_eq!(Weekday::Monday.number_from_monday(), 1);
    /// ```
    #[doc(alias = "iso_weekday_number")]
    pub const fn number_from_monday(self) -> u8 {
        self.number_days_from_monday() + 1
    }

    /// Get the one-indexed number of days from Sunday.
    ///
    /// ```rust
    /// # use time::Weekday;
    /// assert_eq!(Weekday::Monday.number_from_sunday(), 2);
    /// ```
    pub const fn number_from_sunday(self) -> u8 {
        self.number_days_from_sunday() + 1
    }

    /// Get the zero-indexed number of days from Monday.
    ///
    /// ```rust
    /// # use time::Weekday;
    /// assert_eq!(Weekday::Monday.number_days_from_monday(), 0);
    /// ```
    pub const fn number_days_from_monday(self) -> u8 {
        self as _
    }

    /// Get the zero-indexed number of days from Sunday.
    ///
    /// ```rust
    /// # use time::Weekday;
    /// assert_eq!(Weekday::Monday.number_days_from_sunday(), 1);
    /// ```
    pub const fn number_days_from_sunday(self) -> u8 {
        match self {
            Monday => 1,
            Tuesday => 2,
            Wednesday => 3,
            Thursday => 4,
            Friday => 5,
            Saturday => 6,
            Sunday => 0,
        }
    }
}

impl Display for Weekday {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str(match self {
            Monday => "Monday",
            Tuesday => "Tuesday",
            Wednesday => "Wednesday",
            Thursday => "Thursday",
            Friday => "Friday",
            Saturday => "Saturday",
            Sunday => "Sunday",
        })
    }
}

impl FromStr for Weekday {
    type Err = error::InvalidVariant;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "Monday" => Ok(Monday),
            "Tuesday" => Ok(Tuesday),
            "Wednesday" => Ok(Wednesday),
            "Thursday" => Ok(Thursday),
            "Friday" => Ok(Friday),
            "Saturday" => Ok(Saturday),
            "Sunday" => Ok(Sunday),
            _ => Err(error::InvalidVariant),
        }
    }
}