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//! The `Month` enum and its associated `impl`s.
use core::fmt;
use core::num::NonZeroU8;
use core::str::FromStr;
use self::Month::*;
use crate::error;
/// Months of the year.
#[allow(clippy::missing_docs_in_private_items)] // variants
#[repr(u8)]
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum Month {
January = 1,
February = 2,
March = 3,
April = 4,
May = 5,
June = 6,
July = 7,
August = 8,
September = 9,
October = 10,
November = 11,
December = 12,
}
impl Month {
/// Create a `Month` from its numerical value.
pub(crate) const fn from_number(n: NonZeroU8) -> Result<Self, error::ComponentRange> {
match n.get() {
1 => Ok(January),
2 => Ok(February),
3 => Ok(March),
4 => Ok(April),
5 => Ok(May),
6 => Ok(June),
7 => Ok(July),
8 => Ok(August),
9 => Ok(September),
10 => Ok(October),
11 => Ok(November),
12 => Ok(December),
n => Err(error::ComponentRange {
name: "month",
minimum: 1,
maximum: 12,
value: n as _,
conditional_range: false,
}),
}
}
/// Get the previous month.
///
/// ```rust
/// # use time::Month;
/// assert_eq!(Month::January.previous(), Month::December);
/// ```
pub const fn previous(self) -> Self {
match self {
January => December,
February => January,
March => February,
April => March,
May => April,
June => May,
July => June,
August => July,
September => August,
October => September,
November => October,
December => November,
}
}
/// Get the next month.
///
/// ```rust
/// # use time::Month;
/// assert_eq!(Month::January.next(), Month::February);
/// ```
pub const fn next(self) -> Self {
match self {
January => February,
February => March,
March => April,
April => May,
May => June,
June => July,
July => August,
August => September,
September => October,
October => November,
November => December,
December => January,
}
}
/// Get n-th next month.
///
/// ```rust
/// # use time::Month;
/// assert_eq!(Month::January.nth_next(4), Month::May);
/// assert_eq!(Month::July.nth_next(9), Month::April);
/// ```
pub const fn nth_next(self, n: u8) -> Self {
match (self as u8 - 1 + n % 12) % 12 {
0 => January,
1 => February,
2 => March,
3 => April,
4 => May,
5 => June,
6 => July,
7 => August,
8 => September,
9 => October,
10 => November,
val => {
debug_assert!(val == 11);
December
}
}
}
/// Get n-th previous month.
///
/// ```rust
/// # use time::Month;
/// assert_eq!(Month::January.nth_prev(4), Month::September);
/// assert_eq!(Month::July.nth_prev(9), Month::October);
/// ```
pub const fn nth_prev(self, n: u8) -> Self {
match self as i8 - 1 - (n % 12) as i8 {
1 | -11 => February,
2 | -10 => March,
3 | -9 => April,
4 | -8 => May,
5 | -7 => June,
6 | -6 => July,
7 | -5 => August,
8 | -4 => September,
9 | -3 => October,
10 | -2 => November,
11 | -1 => December,
val => {
debug_assert!(val == 0);
January
}
}
}
}
impl fmt::Display for Month {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str(match self {
January => "January",
February => "February",
March => "March",
April => "April",
May => "May",
June => "June",
July => "July",
August => "August",
September => "September",
October => "October",
November => "November",
December => "December",
})
}
}
impl FromStr for Month {
type Err = error::InvalidVariant;
fn from_str(s: &str) -> Result<Self, Self::Err> {
match s {
"January" => Ok(January),
"February" => Ok(February),
"March" => Ok(March),
"April" => Ok(April),
"May" => Ok(May),
"June" => Ok(June),
"July" => Ok(July),
"August" => Ok(August),
"September" => Ok(September),
"October" => Ok(October),
"November" => Ok(November),
"December" => Ok(December),
_ => Err(error::InvalidVariant),
}
}
}
impl From<Month> for u8 {
fn from(month: Month) -> Self {
month as _
}
}
impl TryFrom<u8> for Month {
type Error = error::ComponentRange;
fn try_from(value: u8) -> Result<Self, Self::Error> {
match NonZeroU8::new(value) {
Some(value) => Self::from_number(value),
None => Err(error::ComponentRange {
name: "month",
minimum: 1,
maximum: 12,
value: 0,
conditional_range: false,
}),
}
}
}