Simplify computation for year() of Epoch

nyx-space · Dec 30, 2023 · a16a0a0 · a16a0a0
1 parent 39412e5
commit a16a0a0
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Showing 3 changed files with 16 additions and 23 deletions.
diff --git a/src/duration.rs b/src/duration.rs
@@ -1027,7 +1027,7 @@ impl Add for Duration {
             }
         }
 
-        if me.centuries == Self::MIN.centuries && self.nanoseconds < Self::MIN.nanoseconds {
+        if me.centuries == Self::MIN.centuries {
             // Then we do the operation backward
             match me
                 .nanoseconds

diff --git a/src/epoch.rs b/src/epoch.rs
@@ -13,9 +13,9 @@ use crate::leap_seconds::{LatestLeapSeconds, LeapSecondProvider};
 use crate::parser::Token;
 use crate::{
     Errors, MonthName, TimeScale, BDT_REF_EPOCH, DAYS_PER_YEAR_NLD, ET_EPOCH_S, GPST_REF_EPOCH,
-    GST_REF_EPOCH, J1900_OFFSET, J1900_REF_EPOCH, J2000_TO_J1900_DURATION, MJD_OFFSET,
-    NANOSECONDS_PER_DAY, NANOSECONDS_PER_MICROSECOND, NANOSECONDS_PER_MILLISECOND,
-    NANOSECONDS_PER_SECOND_U32, UNIX_REF_EPOCH,
+    GST_REF_EPOCH, J1900_OFFSET, J2000_TO_J1900_DURATION, MJD_OFFSET, NANOSECONDS_PER_DAY,
+    NANOSECONDS_PER_MICROSECOND, NANOSECONDS_PER_MILLISECOND, NANOSECONDS_PER_SECOND_U32,
+    UNIX_REF_EPOCH,
 };
 
 use crate::efmt::format::Format;
@@ -2504,19 +2504,7 @@ impl Epoch {
     #[must_use]
     /// Returns the number of Gregorian years of this epoch in the current time scale.
     pub fn year(&self) -> i32 {
-        let mut year = Self::compute_gregorian(self.to_duration()).0;
-        if self.time_scale.ref_epoch() != J1900_REF_EPOCH {
-            // We need to correct for the year epoch error
-            let ref_offset_days = (self
-                .time_scale
-                .ref_epoch()
-                .round(DAYS_PER_YEAR_NLD * Unit::Day)
-                - J1900_REF_EPOCH)
-                .to_unit(Unit::Day);
-            let ref_year_offset = ref_offset_days / DAYS_PER_YEAR_NLD;
-            year += ref_year_offset.floor() as i32;
-        }
-        year
+        Self::compute_gregorian(self.duration_since_j1900_tai).0
     }
 
     #[must_use]

diff --git a/tests/epoch.rs b/tests/epoch.rs
@@ -1883,19 +1883,24 @@ fn regression_test_gh_272() {
     assert_eq!(years, 2021);
 
     // Check that even in GPST, we start counting the days at one.
-    let epoch2 = Epoch::from_str("2021-12-31T00:00:00 GPST").unwrap();
-    let (years, day_of_year) = epoch2.year_days_of_year();
+    let epoch = Epoch::from_str("2021-12-31T00:00:00 GPST").unwrap();
+    let (years, day_of_year) = epoch.year_days_of_year();
     assert_eq!(years, 2021);
     assert_eq!(day_of_year, 365.0);
 
-    let epoch2 = Epoch::from_str("2020-12-31T00:00:00 GPST").unwrap();
-    let (years, day_of_year) = epoch2.year_days_of_year();
+    let epoch = Epoch::from_str("2020-12-31T00:00:00 GPST").unwrap();
+    let (years, day_of_year) = epoch.year_days_of_year();
     assert_eq!(years, 2020);
     // 366 days in 2020, leap year.
     assert_eq!(day_of_year, 366.0);
 
-    let epoch2 = Epoch::from_str("2021-01-01T00:00:00 UTC").unwrap();
-    let (years, day_of_year) = epoch2.year_days_of_year();
+    let epoch = Epoch::from_str("2021-01-01T00:00:00 UTC").unwrap();
+    let (years, day_of_year) = epoch.year_days_of_year();
+    assert_eq!(years, 2021);
+    assert_eq!(day_of_year, 1.0);
+
+    let epoch = Epoch::from_str("2021-01-01T00:00:00 GPST").unwrap();
+    let (years, day_of_year) = epoch.year_days_of_year();
     assert_eq!(years, 2021);
     assert_eq!(day_of_year, 1.0);
 }