.

src/XLDates.jl

@@ -1,6 +1,8 @@
 using Dates: Dates, DateTime, length
 import Base: repr, show, +, *, -, /, ^, <, >, ==, isless, convert, promote_rule
 
+const _datetime_xl_epoch = Dates.DateTime(1899, 12, 30)
+
 struct XLDate{T<:Real}
     val::T
     function XLDate(number::T) where {T<:Real}
@@ -13,7 +15,7 @@ struct XLDate{T<:Real}
 end
 
 XLDate(date::DateTime) = begin
-    number = Dates.value(date - Dates.DateTime(1899, 12, 30))
+    number = Dates.value(date - _datetime_xl_epoch)
     number = number / 86400000
     XLDate(number)
 end
@@ -76,7 +78,7 @@ DateTime(xldate::XLDate) = xlnum_to_datetime(xldate.val)
 
 function xlnum_to_datetime(number::Real)
     decimal, whole = modf(number)
-    return Dates.DateTime(1899, 12, 30) +
+    return _datetime_xl_epoch +
            Dates.Day(whole) +
            Dates.Millisecond((Base.floor(decimal * 86400000)))
 end

src/functions.jl

@@ -75,46 +75,60 @@ _text_short_circuit_patterns = [
 ]
 
 function _text_short_circuit(x::Union{Number,XLDate}, format_text::String)
+    function yyyy_mm_dd()
+        datetime = DateTime(XLDate(x))
+
+        yyyy = lpad(Dates.year(datetime), 4, '0')
+        mm = lpad(Dates.month(datetime), 2, '0')
+        dd = lpad(Dates.day(datetime), 2, '0')
+        return yyyy, mm, dd
+    end
+
+    function yyyy_mm_dd_hh_mm_ss()
+        datetime = DateTime(XLDate(x))
+
+        yyyy = lpad(Dates.year(datetime), 4, '0')
+        mm = lpad(Dates.month(datetime), 2, '0')
+        dd = lpad(Dates.day(datetime), 2, '0')
+        hh = lpad(Dates.hour(datetime), 2, '0')
+        mm = lpad(Dates.minute(datetime), 2, '0')
+        ss = lpad(Dates.second(datetime), 2, '0')
+        return yyyy, mm, dd, hh, mm, ss
+    end
+
     lc_format_text = lowercase(format_text)
     if lc_format_text == "yyyymmdd"
-        datetime = DateTime(XLDate(x))
-        formatted_date = Dates.format(datetime, "%Y%m%d")  # Julia doesn't use %Y%m%d for this format
+        yyyy, mm, dd = yyyy_mm_dd()
+        return "$yyyy$mm$dd"
     elseif lc_format_text == "yyyy-mm-dd"
-        datetime = DateTime(XLDate(x))
-        formatted_date = Dates.format(datetime, "%Y-%m-%d")
+        yyyy, mm, dd = yyyy_mm_dd()
+        return "$yyyy-$mm-$dd"
     elseif lc_format_text == "yyyy/mm/dd"
-        datetime = DateTime(XLDate(x))
-        formatted_date = Dates.format(datetime, "%Y/%m/%d")
+        yyyy, mm, dd = yyyy_mm_dd()
+        return "$yyyy/$mm/$dd"
     elseif lc_format_text == "yyyy-mm-dd hh:mm:ss"
-        datetime = DateTime(XLDate(x))
-        formatted_date = Dates.format(datetime, "%Y-%m-%d %H:%M:%S")
+        yyyy, mm, dd, hh, mm, ss = yyyy_mm_dd_hh_mm_ss()
+        return "$yyyy-$mm-$dd $hh:$mm:$ss"
     end
 
     # If not any of these, try a more expensive approach for similar ones
     for pattern in _text_short_circuit_patterns
         m = match(pattern, format_text)
         if m !== nothing
-            # Convert x to DateTime only if a match is found
-            datetime = DateTime(XLDate(x)) # Ensure this conversion is appropriate for your data
-
-            y = lpad(Dates.year(datetime), 4, '0')
-            mon = lpad(Dates.month(datetime), 2, '0')
-            d = lpad(Dates.day(datetime), 2, '0')
-
             if pattern == _text_short_circuit_patterns[1]
+                yyyy, mm, dd = yyyy_mm_dd()
                 sep1 = m[2]
                 sep2 = m[4]
-                return string(y, sep1, mon, sep2, d)
+                return string(yyyy, sep1, mm, sep2, dd)
+
             elseif pattern == _text_short_circuit_patterns[2]
+                yyyy, mm, dd, hh, mm, ss = yyyy_mm_dd_hh_mm_ss()
                 sep1 = m[2]
                 sep2 = m[4]
                 sep3 = m[6]
                 sep4 = m[8]
                 sep5 = m[10]
-                h = lpad(Dates.hour(datetime), 2, '0')
-                min = lpad(Dates.minute(datetime), 2, '0')
-                sec = lpad(Dates.second(datetime), 2, '0')
-                return string(y, sep1, mon, sep2, d, sep3, h, sep4, min, sep5, sec)
+                return string(yyyy, sep1, mm, sep2, dd, sep3, hh, sep4, mm, sep5, ss)
             end
         end
     end
@@ -141,9 +155,8 @@ function text(x::Union{Number,XLDate}, format_text)
     #yy - two-digit year.
     #yyyy - four-digit year.
 
-    quick = _text_short_circuit(x, format_text)
-    if quick !== nothing
-        return quick
+    if (tsc = _text_short_circuit(x, format_text)) !== nothing
+        return tsc
     end
 
     datedict = Dict(

test/runtests.jl

@@ -118,6 +118,7 @@ using XLFunctions
     @test_throws MethodError "2019-01-01" + 1
 end
 
+
 @testitem "ceiling" begin
     # Excel should be ashamed
     @test_throws ArgumentError XLFunctions.ceiling(12.5, -2.5)