Correct leap year calculation (#66)

arp242 · web-flow · commit 72ab962d3467 · 2025-08-01T14:21:27.000-07:00
A leap year is every four years, except for years that are a multiple of
100 and not a multiple of 400.
diff --git a/Sources/Deserializer/Parser.swift b/Sources/Deserializer/Parser.swift
@@ -1347,7 +1347,7 @@ func localDateUTF8(_ utf8: inout Substring.UTF8View) -> (Int, Int, Int)?? {
         return .some(nil)
     }
 
-    let isLeapYear = year % 4 == 0 && year % 100 != 0
+    let isLeapYear = year % 4 == 0 && (year % 100 != 0 || year % 400 == 0)
     if (month == 3 || month == 6 || month == 9 || month == 11) && day > 30 ||
         month == 2 && !isLeapYear && day > 28 ||
         month == 2 && isLeapYear && day > 29 ||

Original file line number	Diff line number	Diff line change
`@@ -1347,7 +1347,7 @@ func localDateUTF8(_ utf8: inout Substring.UTF8View) -> (Int, Int, Int)?? {`
`1347`	`1347`	`return .some(nil)`
`1348`	`1348`	`}`
`1349`	`1349`
`1350`		`- let isLeapYear = year % 4 == 0 && year % 100 != 0`
	`1350`	`+ let isLeapYear = year % 4 == 0 && (year % 100 != 0 \|\| year % 400 == 0)`
`1351`	`1351`	`if (month == 3 \|\| month == 6 \|\| month == 9 \|\| month == 11) && day > 30 \|\|`
`1352`	`1352`	`month == 2 && !isLeapYear && day > 28 \|\|`
`1353`	`1353`	`month == 2 && isLeapYear && day > 29 \|\|`