perf: make Utc2k::unixtime, Utc2k::abs_diff const

CHANGELOG.md

@@ -21,6 +21,11 @@
 
 * Bump MSRV to `1.80`
 
+### Changed
+
+* `Utc2k::unixtime` is now const
+* `Utc2k::abs_diff` is now const
+
 
 
 ## [0.8.1](https://github.com/Blobfolio/utc2k/releases/tag/v0.8.1) - 2024-07-25

src/date/mod.rs

@@ -1794,18 +1794,18 @@ impl Utc2k {
 	/// let date = Utc2k::default(); // 2000-01-01 00:00:00
 	/// assert_eq!(date.unixtime(), Utc2k::MIN_UNIXTIME);
 	/// ```
-	pub fn unixtime(self) -> u32 {
+	pub const fn unixtime(self) -> u32 {
 		// Seconds from the new year up to the start of the month.
-		static MONTH_SECONDS: [u32; 12] = [0, 2_678_400, 5_097_600, 7_776_000, 10_368_000, 13_046_400, 15_638_400, 18_316_800, 20_995_200, 23_587_200, 26_265_600, 28_857_600];
+		const MONTH_SECONDS: [u32; 12] = [0, 2_678_400, 5_097_600, 7_776_000, 10_368_000, 13_046_400, 15_638_400, 18_316_800, 20_995_200, 23_587_200, 26_265_600, 28_857_600];
 
 		// Seconds *before* the new year.
-		static YEAR_SECONDS: [u32; 100] = [946_684_800, 978_307_200, 1_009_843_200, 1_041_379_200, 1_072_915_200, 1_104_537_600, 1_136_073_600, 1_167_609_600, 1_199_145_600, 1_230_768_000, 1_262_304_000, 1_293_840_000, 1_325_376_000, 1_356_998_400, 1_388_534_400, 1_420_070_400, 1_451_606_400, 1_483_228_800, 1_514_764_800, 1_546_300_800, 1_577_836_800, 1_609_459_200, 1_640_995_200, 1_672_531_200, 1_704_067_200, 1_735_689_600, 1_767_225_600, 1_798_761_600, 1_830_297_600, 1_861_920_000, 1_893_456_000, 1_924_992_000, 1_956_528_000, 1_988_150_400, 2_019_686_400, 2_051_222_400, 2_082_758_400, 2_114_380_800, 2_145_916_800, 2_177_452_800, 2_208_988_800, 2_240_611_200, 2_272_147_200, 2_303_683_200, 2_335_219_200, 2_366_841_600, 2_398_377_600, 2_429_913_600, 2_461_449_600, 2_493_072_000, 2_524_608_000, 2_556_144_000, 2_587_680_000, 2_619_302_400, 2_650_838_400, 2_682_374_400, 2_713_910_400, 2_745_532_800, 2_777_068_800, 2_808_604_800, 2_840_140_800, 2_871_763_200, 2_903_299_200, 2_934_835_200, 2_966_371_200, 2_997_993_600, 3_029_529_600, 3_061_065_600, 3_092_601_600, 3_124_224_000, 3_155_760_000, 3_187_296_000, 3_218_832_000, 3_250_454_400, 3_281_990_400, 3_313_526_400, 3_345_062_400, 3_376_684_800, 3_408_220_800, 3_439_756_800, 3_471_292_800, 3_502_915_200, 3_534_451_200, 3_565_987_200, 3_597_523_200, 3_629_145_600, 3_660_681_600, 3_692_217_600, 3_723_753_600, 3_755_376_000, 3_786_912_000, 3_818_448_000, 3_849_984_000, 3_881_606_400, 3_913_142_400, 3_944_678_400, 3_976_214_400, 4_007_836_800, 4_039_372_800, 4_070_908_800];
+		const YEAR_SECONDS: [u32; 100] = [946_684_800, 978_307_200, 1_009_843_200, 1_041_379_200, 1_072_915_200, 1_104_537_600, 1_136_073_600, 1_167_609_600, 1_199_145_600, 1_230_768_000, 1_262_304_000, 1_293_840_000, 1_325_376_000, 1_356_998_400, 1_388_534_400, 1_420_070_400, 1_451_606_400, 1_483_228_800, 1_514_764_800, 1_546_300_800, 1_577_836_800, 1_609_459_200, 1_640_995_200, 1_672_531_200, 1_704_067_200, 1_735_689_600, 1_767_225_600, 1_798_761_600, 1_830_297_600, 1_861_920_000, 1_893_456_000, 1_924_992_000, 1_956_528_000, 1_988_150_400, 2_019_686_400, 2_051_222_400, 2_082_758_400, 2_114_380_800, 2_145_916_800, 2_177_452_800, 2_208_988_800, 2_240_611_200, 2_272_147_200, 2_303_683_200, 2_335_219_200, 2_366_841_600, 2_398_377_600, 2_429_913_600, 2_461_449_600, 2_493_072_000, 2_524_608_000, 2_556_144_000, 2_587_680_000, 2_619_302_400, 2_650_838_400, 2_682_374_400, 2_713_910_400, 2_745_532_800, 2_777_068_800, 2_808_604_800, 2_840_140_800, 2_871_763_200, 2_903_299_200, 2_934_835_200, 2_966_371_200, 2_997_993_600, 3_029_529_600, 3_061_065_600, 3_092_601_600, 3_124_224_000, 3_155_760_000, 3_187_296_000, 3_218_832_000, 3_250_454_400, 3_281_990_400, 3_313_526_400, 3_345_062_400, 3_376_684_800, 3_408_220_800, 3_439_756_800, 3_471_292_800, 3_502_915_200, 3_534_451_200, 3_565_987_200, 3_597_523_200, 3_629_145_600, 3_660_681_600, 3_692_217_600, 3_723_753_600, 3_755_376_000, 3_786_912_000, 3_818_448_000, 3_849_984_000, 3_881_606_400, 3_913_142_400, 3_944_678_400, 3_976_214_400, 4_007_836_800, 4_039_372_800, 4_070_908_800];
 
 		// Add up everything as it would be in a non-leap year.
-		let time = YEAR_SECONDS[usize::from(self.y)] +
-			MONTH_SECONDS[usize::from(self.m - 1)] +
+		let time = YEAR_SECONDS[self.y as usize] +
+			MONTH_SECONDS[self.m as usize - 1] +
 			self.seconds_from_midnight() +
-			DAY_IN_SECONDS * u32::from(self.d - 1);
+			DAY_IN_SECONDS * (self.d as u32 - 1);
 
 		// Add a day's worth of seconds if we need to.
 		if 2 < self.m && self.leap_year() { time + DAY_IN_SECONDS }
@@ -1944,7 +1944,7 @@ impl Utc2k {
 	/// // upper limit to the possible return values…
 	/// assert_eq!(Utc2k::min().abs_diff(Utc2k::max()), 3_155_759_999);
 	/// ```
-	pub fn abs_diff(self, other: Self) -> u32 {
+	pub const fn abs_diff(self, other: Self) -> u32 {
 		self.unixtime().abs_diff(other.unixtime())
 	}