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Share code for month codes, document month indexing
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@Manishearth
Manishearth committed Dec 15, 2023
1 parent 02004c1 commit d30371e
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Showing 3 changed files with 83 additions and 117 deletions.
59 changes: 1 addition & 58 deletions components/calendar/src/chinese.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -228,64 +228,7 @@ impl Calendar for Chinese {
/// leap months. For example, in a year where an intercalary month is added after the second
/// month, the month codes for ordinal months 1, 2, 3, 4, 5 would be "M01", "M02", "M02L", "M03", "M04".
fn month(&self, date: &Self::DateInner) -> types::FormattableMonth {
let ordinal = date.0 .0.month;
let leap_month_option = date.0 .0.year_info.leap_month();
let leap_month = if let Some(leap) = leap_month_option {
leap.get()
} else {
14
};
let code_inner = if leap_month == ordinal {
// Month cannot be 1 because a year cannot have a leap month before the first actual month,
// and the maximum num of months ina leap year is 13.
debug_assert!((2..=13).contains(&ordinal));
match ordinal {
2 => tinystr!(4, "M01L"),
3 => tinystr!(4, "M02L"),
4 => tinystr!(4, "M03L"),
5 => tinystr!(4, "M04L"),
6 => tinystr!(4, "M05L"),
7 => tinystr!(4, "M06L"),
8 => tinystr!(4, "M07L"),
9 => tinystr!(4, "M08L"),
10 => tinystr!(4, "M09L"),
11 => tinystr!(4, "M10L"),
12 => tinystr!(4, "M11L"),
13 => tinystr!(4, "M12L"),
_ => tinystr!(4, "und"),
}
} else {
let mut adjusted_ordinal = ordinal;
if ordinal > leap_month {
// Before adjusting for leap month, if ordinal > leap_month,
// the month cannot be 1 because this implies the leap month is < 1, which is impossible;
// cannot be 2 because that implies the leap month is = 1, which is impossible,
// and cannot be more than 13 because max number of months in a year is 13.
debug_assert!((2..=13).contains(&ordinal));
adjusted_ordinal -= 1;
}
debug_assert!((1..=12).contains(&adjusted_ordinal));
match adjusted_ordinal {
1 => tinystr!(4, "M01"),
2 => tinystr!(4, "M02"),
3 => tinystr!(4, "M03"),
4 => tinystr!(4, "M04"),
5 => tinystr!(4, "M05"),
6 => tinystr!(4, "M06"),
7 => tinystr!(4, "M07"),
8 => tinystr!(4, "M08"),
9 => tinystr!(4, "M09"),
10 => tinystr!(4, "M10"),
11 => tinystr!(4, "M11"),
12 => tinystr!(4, "M12"),
_ => tinystr!(4, "und"),
}
};
let code = types::MonthCode(code_inner);
types::FormattableMonth {
ordinal: ordinal as u32,
code,
}
date.0.month()
}

/// The calendar-specific day-of-month represented by `date`
Expand Down
82 changes: 81 additions & 1 deletion components/calendar/src/chinese_based.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -21,13 +21,14 @@
use crate::{
calendar_arithmetic::{ArithmeticDate, CalendarArithmetic, PrecomputedDataSource},
types::MonthCode,
types::{FormattableMonth, MonthCode},
Calendar, CalendarError, Iso,
};

use calendrical_calculations::chinese_based::{self, ChineseBased, YearBounds};
use calendrical_calculations::rata_die::RataDie;
use core::num::NonZeroU8;
use tinystr::tinystr;

/// The trait ChineseBased is used by Chinese-based calendars to perform computations shared by such calendar.
///
Expand Down Expand Up @@ -194,6 +195,10 @@ impl ChineseBasedYearInfo {
self.new_year + i64::from(self.last_day_of_month[12])
}

/// Get which month is the leap month. This produces the month *number*
/// that is the leap month (not the ordinal month). In other words, for
/// a year with an M05L, this will return Some(5). Note that the regular month precedes
/// the leap month.
pub(crate) fn leap_month(self) -> Option<NonZeroU8> {
self.leap_month
}
Expand Down Expand Up @@ -414,6 +419,76 @@ impl<C: ChineseBasedWithDataLoading + CalendarArithmetic<YearInfo = ChineseBased
pub(crate) fn day_of_year(&self) -> u16 {
self.0.year_info.last_day_of_previous_month(self.0.month) + u16::from(self.0.day)
}

/// The calendar-specific month code represented by `date`;
/// since the Chinese calendar has leap months, an "L" is appended to the month code for
/// leap months. For example, in a year where an intercalary month is added after the second
/// month, the month codes for ordinal months 1, 2, 3, 4, 5 would be "M01", "M02", "M02L", "M03", "M04".
pub(crate) fn month(&self) -> FormattableMonth {
let ordinal = self.0.month;
let leap_month_option = self.0.year_info.leap_month();

// 1 indexed leap month name. This is also the ordinal for the leap month
// in the year (e.g. in `M01, M01L, M02, ..`, the leap month is for month 1, and it is also
// ordinally `month 2`, zero-indexed)
let leap_month = if let Some(leap) = leap_month_option {
leap.get()
} else {
// sentinel value
14
};
let code_inner = if leap_month == ordinal {
// Month cannot be 1 because a year cannot have a leap month before the first actual month,
// and the maximum num of months ina leap year is 13.
debug_assert!((2..=13).contains(&ordinal));
match ordinal {
2 => tinystr!(4, "M01L"),
3 => tinystr!(4, "M02L"),
4 => tinystr!(4, "M03L"),
5 => tinystr!(4, "M04L"),
6 => tinystr!(4, "M05L"),
7 => tinystr!(4, "M06L"),
8 => tinystr!(4, "M07L"),
9 => tinystr!(4, "M08L"),
10 => tinystr!(4, "M09L"),
11 => tinystr!(4, "M10L"),
12 => tinystr!(4, "M11L"),
13 => tinystr!(4, "M12L"),
_ => tinystr!(4, "und"),
}
} else {
let mut adjusted_ordinal = ordinal;
if ordinal > leap_month {
// Before adjusting for leap month, if ordinal > leap_month,
// the month cannot be 1 because this implies the leap month is < 1, which is impossible;
// cannot be 2 because that implies the leap month is = 1, which is impossible,
// and cannot be more than 13 because max number of months in a year is 13.
debug_assert!((2..=13).contains(&ordinal));
adjusted_ordinal -= 1;
}
debug_assert!((1..=12).contains(&adjusted_ordinal));
match adjusted_ordinal {
1 => tinystr!(4, "M01"),
2 => tinystr!(4, "M02"),
3 => tinystr!(4, "M03"),
4 => tinystr!(4, "M04"),
5 => tinystr!(4, "M05"),
6 => tinystr!(4, "M06"),
7 => tinystr!(4, "M07"),
8 => tinystr!(4, "M08"),
9 => tinystr!(4, "M09"),
10 => tinystr!(4, "M10"),
11 => tinystr!(4, "M11"),
12 => tinystr!(4, "M12"),
_ => tinystr!(4, "und"),
}
};
let code = MonthCode(code_inner);
FormattableMonth {
ordinal: ordinal as u32,
code,
}
}
}

impl<C: ChineseBasedWithDataLoading> CalendarArithmetic for C {
Expand Down Expand Up @@ -477,6 +552,7 @@ pub(crate) fn chinese_based_ordinal_lunar_month_from_code(
if code.0.len() == 4 && bytes[3] != b'L' {
return None;
}
// Unadjusted is zero-indexed month index, must add one to it to use
let mut unadjusted = 0;
if bytes[1] == b'0' {
if bytes[2] >= b'1' && bytes[2] <= b'9' {
Expand All @@ -486,13 +562,17 @@ pub(crate) fn chinese_based_ordinal_lunar_month_from_code(
unadjusted = 10 + bytes[2] - b'0';
}
if bytes[3] == b'L' {
// Asked for a leap month that doesn't exist
if unadjusted + 1 != leap_month {
return None;
} else {
// The leap month occurs after the regular month of the same name
return Some(unadjusted + 1);
}
}
if unadjusted != 0 {
// If the month has an index greater than that of the leap month,
// bump it up by one
if unadjusted + 1 > leap_month {
return Some(unadjusted + 1);
} else {
Expand Down
59 changes: 1 addition & 58 deletions components/calendar/src/dangi.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -206,64 +206,7 @@ impl Calendar for Dangi {
}

fn month(&self, date: &Self::DateInner) -> crate::types::FormattableMonth {
let ordinal = date.0 .0.month;
let leap_month_option = date.0 .0.year_info.leap_month();
let leap_month = if let Some(leap) = leap_month_option {
leap.get()
} else {
14
};
let code_inner = if leap_month == ordinal {
// Month cannot be 1 because a year cannot have a leap month before the first actual month,
// and the maximum num of months ina leap year is 13.
debug_assert!((2..=13).contains(&ordinal));
match ordinal {
2 => tinystr!(4, "M01L"),
3 => tinystr!(4, "M02L"),
4 => tinystr!(4, "M03L"),
5 => tinystr!(4, "M04L"),
6 => tinystr!(4, "M05L"),
7 => tinystr!(4, "M06L"),
8 => tinystr!(4, "M07L"),
9 => tinystr!(4, "M08L"),
10 => tinystr!(4, "M09L"),
11 => tinystr!(4, "M10L"),
12 => tinystr!(4, "M11L"),
13 => tinystr!(4, "M12L"),
_ => tinystr!(4, "und"),
}
} else {
let mut adjusted_ordinal = ordinal;
if ordinal > leap_month {
// Before adjusting for leap month, if ordinal > leap_month,
// the month cannot be 1 because this implies the leap month is < 1, which is impossible;
// cannot be 2 because that implies the leap month is = 1, which is impossible,
// and cannot be more than 13 because max number of months in a year is 13.
debug_assert!((2..=13).contains(&ordinal));
adjusted_ordinal -= 1;
}
debug_assert!((1..=12).contains(&adjusted_ordinal));
match adjusted_ordinal {
1 => tinystr!(4, "M01"),
2 => tinystr!(4, "M02"),
3 => tinystr!(4, "M03"),
4 => tinystr!(4, "M04"),
5 => tinystr!(4, "M05"),
6 => tinystr!(4, "M06"),
7 => tinystr!(4, "M07"),
8 => tinystr!(4, "M08"),
9 => tinystr!(4, "M09"),
10 => tinystr!(4, "M10"),
11 => tinystr!(4, "M11"),
12 => tinystr!(4, "M12"),
_ => tinystr!(4, "und"),
}
};
let code = types::MonthCode(code_inner);
types::FormattableMonth {
ordinal: ordinal as u32,
code,
}
date.0.month()
}

fn day_of_month(&self, date: &Self::DateInner) -> crate::types::DayOfMonth {
Expand Down

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