dotnet · BillWagner · Apr 5, 2022 · Apr 3, 2022
@@ -0,0 +1,146 @@
+module Program
+
+open System
+open System.Globalization
+
+let compareForEquality () =
+    // <Snippet1>
+    let tt1 = TimeZoneInfo.TransitionTime.CreateFixedDateRule(DateTime(1, 1, 1, 02, 00, 00), 11, 03)
+    let tt2 = TimeZoneInfo.TransitionTime.CreateFixedDateRule(DateTime(1, 1, 1, 02, 00, 00), 11, 03)
+    let tt3 = TimeZoneInfo.TransitionTime.CreateFloatingDateRule(DateTime(1, 1, 1, 02, 00, 00), 10, 05, DayOfWeek.Sunday)
+    let tz = TimeZoneInfo.Local
+    printfn $"{tt1.Equals tz}"         // Returns False (overload with argument of type Object)
+    printfn $"{tt1.Equals tt1}"        // Returns True (an object always equals itself)
+    printfn $"{tt1.Equals tt2}"        // Returns True (identical property values)
+    printfn $"{tt1.Equals tt3}"        // Returns False (different property values)
+    // </Snippet1>
+
+let compareTransitionTimesForEquality () =
+    // <Snippet7>
+    let tt1 = TimeZoneInfo.TransitionTime.CreateFixedDateRule(DateTime(1, 1, 1, 02, 00, 00), 11, 03)
+    let tt2 = TimeZoneInfo.TransitionTime.CreateFixedDateRule(DateTime(1, 1, 1, 02, 00, 00), 11, 03)
+    let tt3 = TimeZoneInfo.TransitionTime.CreateFloatingDateRule(DateTime(1, 1, 1, 02, 00, 00), 10, 05, DayOfWeek.Sunday)
+    printfn $"{tt1.Equals tt1}"        // Returns True (an object always equals itself)
+    printfn $"{tt1.Equals tt2}"        // Returns True (identical property values)
+    printfn $"{tt1.Equals tt3}"        // Returns False (different property values)
+    // </Snippet7>
+
+let createTransitionRules () =
+    // <Snippet2>
+    let delta = TimeSpan(1, 0, 0)
+    let adjustmentList = ResizeArray()
+
+    // Define a fictitious new time zone consisting of fixed and floating adjustment rules 
+    // Define fixed rule (for 1900-1955)
+    let transitionRuleStart = TimeZoneInfo.TransitionTime.CreateFixedDateRule(DateTime(1, 1, 1, 2, 0, 0), 3, 15)
+    let transitionRuleEnd = TimeZoneInfo.TransitionTime.CreateFixedDateRule(DateTime(1, 1, 1, 3, 0, 0), 11, 15)
+    let adjustment = 
+        TimeZoneInfo.AdjustmentRule.CreateAdjustmentRule(DateTime(1900, 1, 1), DateTime(1955, 12, 31), delta, transitionRuleStart, transitionRuleEnd)
+    adjustmentList.Add adjustment
+    // Define floating rule (for 1956- )
+    let transitionRuleStart = TimeZoneInfo.TransitionTime.CreateFloatingDateRule(DateTime(1, 1, 1, 2, 0, 0), 3, 5, DayOfWeek.Sunday)
+    let transitionRuleEnd = TimeZoneInfo.TransitionTime.CreateFloatingDateRule(DateTime(1, 1, 1, 3, 0, 0), 10, 4, DayOfWeek.Sunday) 
+    let adjustment = TimeZoneInfo.AdjustmentRule.CreateAdjustmentRule(DateTime(1956, 1, 1), DateTime.MaxValue.Date, delta, transitionRuleStart, transitionRuleEnd)
+    adjustmentList.Add adjustment 
+
+    // Create fictitious time zone   
+    let imaginaryTZ = 
+        TimeZoneInfo.CreateCustomTimeZone("Fictitious Standard Time", TimeSpan(-9, 0, 0), 
+                    "(GMT-09:00) Fictitious Time", "Fictitious Standard Time", 
+                    "Fictitious Daylight Time", adjustmentList.ToArray())
+    // </Snippet2> 
+    ()
+
+// <Snippet3>
+let getFixedTransitionTimes () =
+    let timeZones = TimeZoneInfo.GetSystemTimeZones()
+    let dateInfo = CultureInfo.CurrentCulture.DateTimeFormat
+    for zone in timeZones do
+        let adjustmentRules = zone.GetAdjustmentRules()
+        for adjustmentRule in adjustmentRules do
+            let daylightStart = adjustmentRule.DaylightTransitionStart
+            if daylightStart.IsFixedDateRule then
+                printfn $"For {zone.StandardName}, daylight savings time begins at {daylightStart.TimeOfDay:t} on {dateInfo.GetMonthName daylightStart.Month} {daylightStart.Day} from {adjustmentRule.DateStart:d} to {adjustmentRule.DateEnd:d}." 
+            let daylightEnd = adjustmentRule.DaylightTransitionEnd
+            if daylightEnd.IsFixedDateRule then
+                printfn $"For {zone.StandardName}, daylight savings time ends at {daylightEnd.TimeOfDay:t} on {dateInfo.GetMonthName daylightEnd.Month} {daylightEnd.Day} from {adjustmentRule.DateStart:d} to {adjustmentRule.DateEnd:d}." 
+// </Snippet3>
+
+// <Snippet4>
+type WeekOfMonth =
+    | First = 1
+    | Second = 2
+    | Third = 3
+    | Fourth = 4
+    | Last = 5
+
+let getFloatingTransitionTimes () =
+    let timeZones = TimeZoneInfo.GetSystemTimeZones()
+    for zone in timeZones do
+        let adjustmentRules = zone.GetAdjustmentRules()
+        let dateInfo = CultureInfo.CurrentCulture.DateTimeFormat
+        for adjustmentRule in adjustmentRules do
+            let daylightStart = adjustmentRule.DaylightTransitionStart
+            if not daylightStart.IsFixedDateRule then
+                printfn $"{zone.StandardName}, {adjustmentRule.DateStart:d}-{adjustmentRule.DateEnd:d}: Begins at {daylightStart.TimeOfDay:t} on the {enum<WeekOfMonth> daylightStart.Week} {daylightStart.DayOfWeek} of {dateInfo.GetMonthName daylightStart.Month}." 
+
+            let daylightEnd = adjustmentRule.DaylightTransitionEnd
+            if not daylightEnd.IsFixedDateRule then
+                printfn $"{zone.StandardName}, {adjustmentRule.DateStart:d}-{adjustmentRule.DateEnd:d}: Ends at {daylightEnd.TimeOfDay:t} on the {enum<WeekOfMonth> daylightEnd.Week} {daylightEnd.DayOfWeek} of {dateInfo.GetMonthName daylightEnd.Month}." 
+// </Snippet4>
+
+module AdditionalExamples =
+    // <Snippet6>
+    type WeekOfMonth =
+        | First = 1
+        | Second = 2
+        | Third = 3
+        | Fourth = 4
+        | Last = 5
+
+    let getAllTransitionTimes () =
+        let timeZones = TimeZoneInfo.GetSystemTimeZones()
+        let dateInfo = CultureInfo.CurrentCulture.DateTimeFormat
+
+        for zone in timeZones do
+            printfn $"{zone.StandardName} transition time information:"
+            let adjustmentRules= zone.GetAdjustmentRules()
+
+            // Indicate that time zone has no adjustment rules
+            if adjustmentRules.Length = 0 then
+                printfn "   No adjustment rules defined."
+            else
+                // Iterate adjustment rules       
+                for adjustmentRule in adjustmentRules do
+                    printfn $"   Adjustment rule from {adjustmentRule.DateStart:d} to {adjustmentRule.DateEnd:d}:"                                 
+
+                    // Get start of transition
+                    let daylightStart = adjustmentRule.DaylightTransitionStart
+                    // Display information on fixed date rule
+                    if not daylightStart.IsFixedDateRule then
+                        printfn $"      Begins at {daylightStart.TimeOfDay:t} on the {enum<WeekOfMonth> daylightStart.Week} {daylightStart.DayOfWeek} of {dateInfo.GetMonthName daylightStart.Month}."
+                    // Display information on floating date rule 
+                    else
+                        printfn $"      Begins at {daylightStart.TimeOfDay:t} on the {enum<WeekOfMonth> daylightStart.Week} {daylightStart.DayOfWeek} of {dateInfo.GetMonthName daylightStart.Month}."
+
+                    // Get end of transition
+                    let daylightEnd = adjustmentRule.DaylightTransitionEnd
+                    // Display information on fixed date rule
+                    if not daylightEnd.IsFixedDateRule then
+                        printfn $"      Ends at {daylightEnd.TimeOfDay:t} on the {enum<WeekOfMonth> daylightEnd.Week} {daylightEnd.DayOfWeek} of {dateInfo.GetMonthName daylightEnd.Month}."
+                    // Display information on floating date rule
+                    else
+                        printfn $"      Ends at {daylightStart.TimeOfDay:t} on the {enum<WeekOfMonth> daylightStart.Week} {daylightStart.DayOfWeek} of {dateInfo.GetMonthName daylightStart.Month}."
+    // </Snippet6>
+
+compareForEquality ()
+printfn ""
+compareTransitionTimesForEquality()
+printfn ""
+createTransitionRules()
+printfn ""
+getFixedTransitionTimes ()
+printfn ""
+getFloatingTransitionTimes ()
+printfn ""
+AdditionalExamples.getAllTransitionTimes ()
@@ -0,0 +1,83 @@
+module example1
+
+// <Snippet5>
+open System
+open System.Globalization
+
+let displayTransitionInfo (transition: TimeZoneInfo.TransitionTime) year label =
+    // For non-fixed date rules, get local calendar
+    let cal = CultureInfo.CurrentCulture.Calendar
+    // Get first day of week for transition
+    // For example, the 3rd week starts no earlier than the 15th of the month
+    let startOfWeek = transition.Week * 7 - 6
+    // What day of the week does the month start on?
+    let firstDayOfWeek = cal.GetDayOfWeek(DateTime(year, transition.Month, 1)) |> int 
+    // Determine how much start date has to be adjusted
+    let changeDayOfWeek = int transition.DayOfWeek
+
+    let transitionDay = 
+        if firstDayOfWeek <= changeDayOfWeek then
+            startOfWeek + (changeDayOfWeek - firstDayOfWeek)
+        else     
+            startOfWeek + (7 - firstDayOfWeek + changeDayOfWeek)
+
+    // Adjust for months with no fifth week
+    let transitionDay =
+        if transitionDay > cal.GetDaysInMonth(year, transition.Month) then  
+            transitionDay - 7
+        else 
+            transitionDay
+
+    printfn $"   {label} {transition.DayOfWeek}, {DateTime(year, transition.Month, transitionDay):d} at {transition.TimeOfDay:t}"   
+
+let getAdjustment (adjustments: TimeZoneInfo.AdjustmentRule seq) year =
+    adjustments
+    // Iterate adjustment rules for time zone
+    // Determine if this adjustment rule covers year desired
+    |> Seq.tryFind (fun adjustment -> adjustment.DateStart.Year <= year && adjustment.DateEnd >= DateTime year)
+    |> Option.defaultValue null
+
+let getTransitionTimes year =
+    // Instantiate DateTimeFormatInfo object for month names
+    let dateFormat = CultureInfo.CurrentCulture.DateTimeFormat
+
+    // Get and iterate time zones on local computer
+    let timeZones = TimeZoneInfo.GetSystemTimeZones()
+    for timeZone in timeZones do
+        printfn $"{timeZone.StandardName}:"
+        let adjustments = timeZone.GetAdjustmentRules()
+        let startYear = year
+        let mutable endYear = startYear
+
+        if adjustments.Length = 0 then
+            printfn "   No adjustment rules."
+        else
+            let adjustment = getAdjustment adjustments year
+            if adjustment = null then
+                Console.WriteLine("   No adjustment rules available for this year.")
+            else
+                // Determine if starting transition is fixed 
+                let startTransition = adjustment.DaylightTransitionStart
+                // Determine if starting transition is fixed and display transition info for year
+                if startTransition.IsFixedDateRule then
+                    printfn $"   Begins on {dateFormat.GetMonthName startTransition.Month} {startTransition.Day} at {startTransition.TimeOfDay:t}"
+                else
+                    displayTransitionInfo startTransition startYear "Begins on"
+
+                // Determine if ending transition is fixed and display transition info for year
+                let mutable endTransition = adjustment.DaylightTransitionEnd
+
+                // Does the transition back occur in an earlier month (i.e., 
+                // the following year) than the transition to DST? If so, make
+                // sure we have the right adjustment rule.
+                if endTransition.Month < startTransition.Month then
+                    endTransition <- (getAdjustment adjustments (year + 1)).DaylightTransitionEnd
+                    endYear <- endYear + 1
+
+                if endTransition.IsFixedDateRule then
+                    printfn $"   Ends on {dateFormat.GetMonthName endTransition.Month} {endTransition.Day} at {endTransition.TimeOfDay:t}"
+                else
+                    displayTransitionInfo endTransition endYear "Ends on"
+
+// </Snippet5>
+getTransitionTimes 2007
@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="example1.fs" />
+    <Compile Include="System.TimeZone2.TransitionTime.Class.fs" />
+  </ItemGroup>
+</Project>