Remove prev_year info (#6382)

This became dead code in #6319

Author: robertbastian

components/calendar/src/cal/hijri.rs

@@ -220,44 +220,9 @@ impl HijriTabular {
     }
 }
 
-/// Compact representation of the length of a Hijri year.
-#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord)]
-enum HijriYearLength {
-    /// Long (355-day) Hijri year
-    L355,
-    /// Short (354-day) Hijri year
-    L354,
-    /// Unexpectedly Short (353-day) Hijri year
-    ///
-    /// It is probably a bug when this year length is returned. See:
-    /// <https://github.com/unicode-org/icu4x/issues/4930>
-    L353,
-}
-
-impl Default for HijriYearLength {
-    fn default() -> Self {
-        Self::L354
-    }
-}
-
-impl HijriYearLength {
-    const LONG: u16 = 355;
-    const SHORT: u16 = 354;
-
-    fn try_from_int(value: i64) -> Option<Self> {
-        match value {
-            355 => Some(Self::L355),
-            354 => Some(Self::L354),
-            353 => Some(Self::L353),
-            _ => None,
-        }
-    }
-}
-
 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord)]
 pub(crate) struct HijriYearInfo<IB: IslamicBased> {
-    packed_data: PackedHijriYearInfo,
-    prev_year_length: HijriYearLength,
+    pub(crate) packed_data: PackedHijriYearInfo,
     model: IB,
     value: i32,
 }
@@ -268,56 +233,58 @@ impl<IB: IslamicBased> From<HijriYearInfo<IB>> for i32 {
     }
 }
 
+const LONG_YEAR_LEN: u16 = 355;
+const SHORT_YEAR_LEN: u16 = 354;
+
 impl<IB: IslamicBased> HijriYearInfo<IB> {
-    pub(crate) fn new(
-        prev_packed: PackedHijriYearInfo,
-        this_packed: PackedHijriYearInfo,
+    pub(crate) fn from_packed(
+        packed_data: PackedHijriYearInfo,
         extended_year: i32,
         model: IB,
     ) -> Self {
-        let days_in_year = prev_packed.days_in_year();
-        let days_in_year = match HijriYearLength::try_from_int(days_in_year as i64) {
-            Some(x) => x,
-            None => {
-                debug_assert!(false, "Found wrong year length for Hijri year {extended_year}: Expected 355, 354, or 353, got {days_in_year}");
-                Default::default()
-            }
-        };
         Self {
-            prev_year_length: days_in_year,
-            packed_data: this_packed,
+            packed_data,
             model,
             value: extended_year,
         }
     }
 
-    fn compute_for_year(extended_year: i32, model: IB) -> Self {
+    pub(crate) fn compute_for_year(extended_year: i32, model: IB) -> Self {
         let ny = model.fixed_from_islamic(extended_year, 1, 1);
-        let packed_data = PackedHijriYearInfo::compute_with_ny(extended_year, ny, model);
-        let prev_ny = model.fixed_from_islamic(extended_year - 1, 1, 1);
-        let rd_diff = ny - prev_ny;
-        let rd_diff = match HijriYearLength::try_from_int(rd_diff) {
-            Some(x) => x,
-            None => {
-                debug_assert!(false, "({}) Found wrong year length for Hijri year {extended_year}: Expected 355, 354, or 353, got {rd_diff}", IB::DEBUG_NAME);
-                Default::default()
-            }
-        };
-        Self {
-            prev_year_length: rd_diff,
-            packed_data,
+        let month_lengths = model.month_lengths_for_year(extended_year, ny);
+        let ny_offset = ny - IB::mean_synodic_ny(extended_year);
+        let r = Self {
+            packed_data: PackedHijriYearInfo::new(month_lengths, ny_offset),
             model,
             value: extended_year,
+        };
+        if !matches!(r.days_in_year(), SHORT_YEAR_LEN | LONG_YEAR_LEN | 353) {
+            // See https://github.com/unicode-org/icu4x/issues/4930
+            debug_assert!(false, "({}) Found wrong year length for Hijri year {extended_year}: Expected 355, 354, or 353, got {}", IB::DEBUG_NAME, r.days_in_year());
         }
+        r
     }
 
     fn compute_for_fixed(fixed: RataDie, model: IB) -> Self {
         let (y, _m, _d) = model.islamic_from_fixed(fixed);
         Self::compute_for_year(y, model)
     }
 
+    /// The number of days in a given 1-indexed month
+    pub(crate) fn days_in_month(self, month: u8) -> u8 {
+        if self.packed_data.month_has_30_days(month) {
+            30
+        } else {
+            29
+        }
+    }
+
+    pub(crate) fn days_in_year(self) -> u16 {
+        self.packed_data.last_day_of_month(12)
+    }
+
     /// Get the new year R.D. given the extended year that this yearinfo is for    
-    fn new_year(self) -> RataDie {
+    pub(crate) fn new_year(self) -> RataDie {
         IB::mean_synodic_ny(self.value) + self.packed_data.ny_offset()
     }
 
@@ -401,20 +368,20 @@ impl CalendarArithmetic for HijriObservational {
     type YearInfo = HijriYearInfo<ObservationalIslamic>;
 
     fn days_in_provided_month(year: Self::YearInfo, month: u8) -> u8 {
-        year.packed_data.days_in_month(month)
+        year.days_in_month(month)
     }
 
     fn months_in_provided_year(_year: Self::YearInfo) -> u8 {
         12
     }
 
     fn days_in_provided_year(year: Self::YearInfo) -> u16 {
-        year.packed_data.days_in_year()
+        year.days_in_year()
     }
 
     // As an true lunar calendar, it does not have leap years.
     fn provided_year_is_leap(year: Self::YearInfo) -> bool {
-        year.packed_data.days_in_year() != HijriYearLength::SHORT
+        year.days_in_year() != SHORT_YEAR_LEN
     }
 
     fn last_month_day_in_provided_year(year: Self::YearInfo) -> (u8, u8) {
@@ -574,20 +541,20 @@ impl CalendarArithmetic for HijriUmmAlQura {
     type YearInfo = HijriYearInfo<SaudiIslamic>;
 
     fn days_in_provided_month(year: Self::YearInfo, month: u8) -> u8 {
-        year.packed_data.days_in_month(month)
+        year.days_in_month(month)
     }
 
     fn months_in_provided_year(_year: HijriYearInfo<SaudiIslamic>) -> u8 {
         12
     }
 
     fn days_in_provided_year(year: Self::YearInfo) -> u16 {
-        year.packed_data.days_in_year()
+        year.days_in_year()
     }
 
     // As an true lunar calendar, it does not have leap years.
     fn provided_year_is_leap(year: Self::YearInfo) -> bool {
-        year.packed_data.days_in_year() != HijriYearLength::SHORT
+        year.days_in_year() != SHORT_YEAR_LEN
     }
 
     fn last_month_day_in_provided_year(year: HijriYearInfo<SaudiIslamic>) -> (u8, u8) {
@@ -759,9 +726,9 @@ impl CalendarArithmetic for HijriCivil {
 
     fn days_in_provided_year(year: i32) -> u16 {
         if Self::provided_year_is_leap(year) {
-            HijriYearLength::LONG
+            LONG_YEAR_LEN
         } else {
-            HijriYearLength::SHORT
+            SHORT_YEAR_LEN
         }
     }
 
@@ -937,9 +904,9 @@ impl CalendarArithmetic for HijriTabular {
 
     fn days_in_provided_year(year: i32) -> u16 {
         if Self::provided_year_is_leap(year) {
-            HijriYearLength::LONG
+            LONG_YEAR_LEN
         } else {
-            HijriYearLength::SHORT
+            SHORT_YEAR_LEN
         }
     }
 

components/calendar/src/provider/hijri.rs

@@ -62,7 +62,7 @@ impl HijriCache<'_> {
     pub fn compute_for<IB: IslamicBased>(extended_years: core::ops::Range<i32>, model: IB) -> Self {
         let data = extended_years
             .clone()
-            .map(|year| PackedHijriYearInfo::compute(year, model))
+            .map(|year| HijriYearInfo::compute_for_year(year, model).packed_data)
             .collect();
         HijriCache {
             first_extended_year: extended_years.start,
@@ -76,22 +76,12 @@ impl HijriCache<'_> {
         extended_year: i32,
         model: IB,
     ) -> Option<HijriYearInfo<IB>> {
-        let delta = extended_year - self.first_extended_year;
-        let delta = usize::try_from(delta).ok()?;
+        let packed_data = self
+            .data
+            .get(usize::try_from(extended_year - self.first_extended_year).ok()?)?;
 
-        if delta == 0 {
-            return None;
-        }
-
-        let (Some(this_packed), Some(prev_packed)) =
-            (self.data.get(delta), self.data.get(delta - 1))
-        else {
-            return None;
-        };
-
-        Some(HijriYearInfo::new(
-            prev_packed,
-            this_packed,
+        Some(HijriYearInfo::from_packed(
+            packed_data,
             extended_year,
             model,
         ))
@@ -106,44 +96,17 @@ impl HijriCache<'_> {
     ) -> Option<HijriYearInfo<IB>> {
         let extended_year = IB::approximate_islamic_from_fixed(fixed);
 
-        let delta = extended_year - self.first_extended_year;
-        let delta = usize::try_from(delta).ok()?;
-
-        if delta <= 1 {
-            return None;
-        }
-
-        let this_packed = self.data.get(delta)?;
-        let prev_packed = self.data.get(delta + 1)?;
+        let year = self.get_for_extended_year(extended_year, model)?;
 
-        let this_ny = IB::mean_synodic_ny(extended_year) + this_packed.ny_offset();
-
-        if fixed < this_ny {
-            let prev2_packed = self.data.get(delta - 2)?;
-            return Some(HijriYearInfo::new(
-                prev2_packed,
-                prev_packed,
-                extended_year - 1,
-                model,
-            ));
-        }
-        let next_packed = self.data.get(delta + 1)?;
-        let next_ny = IB::mean_synodic_ny(extended_year + 1) + next_packed.ny_offset();
-
-        if fixed >= next_ny {
-            Some(HijriYearInfo::new(
-                this_packed,
-                next_packed,
-                extended_year + 1,
-                model,
-            ))
+        if fixed < year.new_year() {
+            self.get_for_extended_year(extended_year - 1, model)
         } else {
-            Some(HijriYearInfo::new(
-                prev_packed,
-                this_packed,
-                extended_year,
-                model,
-            ))
+            let next_year = self.get_for_extended_year(extended_year + 1, model)?;
+            Some(if fixed < next_year.new_year() {
+                year
+            } else {
+                next_year
+            })
         }
     }
 }
@@ -195,7 +158,6 @@ impl PackedHijriYearInfo {
         let mut all = 0u16; // last byte unused
 
         for (month, length_30) in month_lengths.iter().enumerate() {
-            #[allow(clippy::indexing_slicing)]
             if *length_30 {
                 all |= 1 << month as u16;
             }
@@ -230,15 +192,6 @@ impl PackedHijriYearInfo {
         months & (1 << (month - 1) as u16) != 0
     }
 
-    /// The number of days in a given 1-indexed month
-    pub(crate) fn days_in_month(self, month: u8) -> u8 {
-        if self.month_has_30_days(month) {
-            30
-        } else {
-            29
-        }
-    }
-
     // Which day of year is the last day of a month (month is 1-indexed)
     pub(crate) fn last_day_of_month(self, month: u8) -> u16 {
         let months = u16::from_le_bytes([self.0, self.1]);
@@ -251,25 +204,6 @@ impl PackedHijriYearInfo {
         prev_month_lengths += long_month_bits.count_ones().try_into().unwrap_or(0);
         prev_month_lengths
     }
-
-    pub(crate) fn days_in_year(self) -> u16 {
-        self.last_day_of_month(12)
-    }
-
-    pub(crate) fn compute_with_ny<IB: IslamicBased>(
-        extended_year: i32,
-        ny: RataDie,
-        model: IB,
-    ) -> Self {
-        let month_lengths = model.month_lengths_for_year(extended_year, ny);
-        let ny_offset = ny - IB::mean_synodic_ny(extended_year);
-        Self::new(month_lengths, ny_offset)
-    }
-    #[cfg(feature = "datagen")]
-    pub(crate) fn compute<IB: IslamicBased>(extended_year: i32, model: IB) -> Self {
-        let ny = model.fixed_from_islamic(extended_year, 1, 1);
-        Self::compute_with_ny(extended_year, ny, model)
-    }
 }
 
 impl AsULE for PackedHijriYearInfo {