[m-rev.] for review: implement io__file_modification_time_2 in C#

[Peter Ross]

diff -u library/time.m library/time.m
--- library/time.m
+++ library/time.m
@@ -176,7 +176,7 @@
 
 :- implementation.
 
-:- import_module int, exception.
+:- import_module int, exception, list, require, string.
 
 :- pragma foreign_decl("C",
 "
@@ -211,6 +211,8 @@
 :- type time_t_rep ---> time_t_rep(c_pointer).
 :- pragma foreign_type("C", time_t_rep, "time_t")
 	where comparison is compare_time_t_reps.
+
+	% The System.DateTime will hold the value in UTC.
 :- pragma foreign_type(il, time_t_rep, "valuetype [mscorlib]System.DateTime")
 	where comparison is compare_time_t_reps.
 
@@ -241,12 +243,14 @@
 	Ret = (MR_Integer) clock();
 	MR_update_io(IO0, IO);
 }").
+/* XXX need to add System.dll to the references list.
 :- pragma foreign_proc("C#", time__c_clock(Ret::out, _IO0::di, _IO::uo),
 	[will_not_call_mercury, promise_pure, tabled_for_io],
 "{
 	// XXX Ticks is long in .NET!
-	Ret = (int) System.DateTime.Now.Ticks;
+	Ret = (int) System.Diagnostics.Process.GetCurrentProcess.UserProcessorTime.Ticks;
 }").
+*/
 
 %-----------------------------------------------------------------------------%
 
@@ -362,7 +366,7 @@
 	time__c_time(Ret::out, _IO0::di, _IO::uo),
 	[will_not_call_mercury, promise_pure, tabled_for_io],
 "{
-	Ret = System.DateTime.Now;
+	Ret = System.DateTime.UtcNow;
 }").
 
 :- pred time__time_t_is_invalid(time_t_rep).
@@ -405,7 +409,7 @@
 "{
 	System.TimeSpan span;
 	span = T1 - T0;
-	Diff = span.Ticks / System.TimeSpan.TicksPerSecond;
+	Diff = span.TotalSeconds;
 }").
 
 %-----------------------------------------------------------------------------%
@@ -461,8 +465,11 @@
 	WD = (int) t.DayOfWeek;
 	MD = t.Day;
 	YD = t.DayOfYear - 1;
-	// XXX Don't know how to determine if in DST.
-	N = -1;
+	if (System.TimeZone.CurrentTimeZone.IsDaylightSavingTime(t)) {
+		N = 1;
+	} else {
+		N = 0;
+	}
 }").
 
 
@@ -506,7 +513,7 @@
 		Min::out, Sec::out, YD::out, WD::out, N::out),
 	[will_not_call_mercury, promise_pure],
 "{
-	System.DateTime t = Time.ToUniversalTime();
+	System.DateTime t = Time;
 
 	// we don't handle leap seconds
 	Sec = t.Second;
@@ -517,8 +524,8 @@
 	WD = (int) t.DayOfWeek;
 	MD = t.Day;
 	YD = t.DayOfYear - 1;
-	// XXX Don't know how to determine if in DST.
-	N = -1;
+	// UTC time can never have daylight savings.
+	N = 0;
 }").
 
 :- func int_to_maybe_dst(int) = maybe(dst).
@@ -569,6 +576,11 @@
 	[will_not_call_mercury, promise_pure],
  "{
 	// We don't use YD, WD and N.
+	// XXX Ignoring N the daylight savings time indicator is bad
+	// On the day when you switch back to standard time from daylight
+	// savings time, the time '2:30am' occurs twice, once during daylight
+	// savings time (N = 1), and then again an hour later, during standard
+	// time (N = 0).
  	Time = new System.DateTime(Yr + 1900, Mnt + 1, MD, Hrs, Min, Sec);
 }").
 
@@ -588,78 +600,60 @@
 %:- func time__asctime(tm) = string.
 
 time__asctime(TM) = Str :-
-	TM = tm(Yr, Mnt, MD, Hrs, Min, Sec, YD, WD, DST),
-	time__c_asctime(Yr, Mnt, MD, Hrs, Min, Sec, YD, WD,
-		maybe_dst_to_int(DST), Str).
-
-:- pred time__c_asctime(int, int, int, int, int, int, int, int, int, string).
-:- mode time__c_asctime(in, in, in, in, in, in, in, in, in, out) is det.
-
-:- pragma foreign_proc("C",
-	time__c_asctime(Yr::in, Mnt::in, MD::in, Hrs::in, Min::in, Sec::in,
-		YD::in, WD::in, N::in, Str::out),
-	[will_not_call_mercury, promise_pure],
-"{
-	struct tm t;
-	char* s;
-
-	t.tm_sec = Sec;
-	t.tm_min = Min;
-	t.tm_hour = Hrs;
-	t.tm_mon = Mnt;
-	t.tm_year = Yr;
-	t.tm_wday = WD;
-	t.tm_mday = MD;
-	t.tm_yday = YD;
-	t.tm_isdst = N;
-
-	s = asctime(&t);
-
-	MR_make_aligned_string_copy(Str, s);
-}").
-:- pragma foreign_proc("C#",
-	time__c_asctime(Yr::in, Mnt::in, MD::in, Hrs::in, Min::in, Sec::in,
-		_YD::in, _WD::in, _N::in, Str::out),
-	[will_not_call_mercury, promise_pure],
-"{
-	// We don't use YD, WD and N.
- 	System.DateTime Time = new System.DateTime(Yr + 1900, Mnt + 1, MD,
-								Hrs, Min, Sec);
+	TM = tm(Yr, Mnt, MD, Hrs, Min, Sec, _YD, WD, _DST),
+	Str = string__format("%.3s %.3s%3d %.2d:%.2d:%.2d %d\n",
+			[s(wday_name(WD)), s(mon_name(Mnt)), i(MD), i(Hrs),
+				i(Min), i(Sec), i(1900 + Yr)]).
+
+:- func wday_name(int) = string.
+
+wday_name(N) = Name :-
+	( wday_name(N, Name0) ->
+		Name = Name0
+	;
+		error("time: wday_name")
+	).
+
+:- pred wday_name(int::in, string::out) is semidet.
+
+wday_name(0, "Mon").
+wday_name(1, "Tue").
+wday_name(2, "Wed").
+wday_name(3, "Thu").
+wday_name(4, "Fri").
+wday_name(5, "Sat").
+wday_name(6, "Sun").
+
+:- func mon_name(int) = string.
+
+mon_name(N) = Name :-
+	( mon_name(N, Name0) ->
+		Name = Name0
+	;
+		error("time: mon_name")
+	).
+
+:- pred mon_name(int::in, string::out) is semidet.
+
+mon_name(0, "Jan").
+mon_name(1, "Feb").
+mon_name(2, "Mar").
+mon_name(3, "Apr").
+mon_name(4, "May").
+mon_name(5, "Jun").
+mon_name(6, "Jul").
+mon_name(7, "Aug").
+mon_name(8, "Sep").
+mon_name(9, "Oct").
+mon_name(10, "Nov").
+mon_name(11, "Dec").
 
-	// XXX this may need to be formatted differently.
-	Str = Time.ToString();
-}").
 
 %-----------------------------------------------------------------------------%
 
 %:- func time__ctime(time_t) = string.
 
-time__ctime(time_t(Time)) = Str :-
-	time__c_ctime(Time, Str).
-
-:- pred time__c_ctime(time_t_rep, string).
-:- mode time__c_ctime(in, out) is det.
-
-:- pragma foreign_proc("C",
-	time__c_ctime(Time::in, Str::out),
-	[will_not_call_mercury, promise_pure],
-"{
-	char *s;
-	time_t t;
-
-	t = Time;
-
-	s = ctime(&t);
-
-	MR_make_aligned_string_copy(Str, s);
-}").
-:- pragma foreign_proc("C",
-	time__c_ctime(Time::in, Str::out),
-	[will_not_call_mercury, promise_pure],
-"{
-	// XXX this may need to be formatted differently.
-	Str = Time.ToString();
-}").
+time__ctime(Time) = asctime(localtime(Time)).
 
 %-----------------------------------------------------------------------------%
 
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