[m-rev.] for review: Java implementation of time library (revised)

[Fergus Henderson]

On 15-Dec-2003, James Goddard <goddardjames at yahoo.com> wrote:
> Implemented some library functions for the time library in java.

That looks good now, but I think it is worth adding some test cases
to test the tricky times around the daylight savings time transition.

> +:- pragma foreign_proc("Java",
> +	time__c_mktime(Yr::in, Mnt::in, MD::in, Hrs::in, Min::in, Sec::in,
> +		_YD::in, _WD::in, N::in, Time::out),
> +	[will_not_call_mercury, promise_pure],
> +"
> +	java.util.GregorianCalendar gc = new java.util.GregorianCalendar(
> +			Yr + 1900, Mnt, MD, Hrs, Min, Sec);
> +
> +	Time = gc.getTime();
> +
> +	// If the time we constructed is not in daylight savings time, but
> +	// it should be, we need to add the DST offset.
> +	if (N == 1 && gc.getTimeZone().inDaylightTime(Time) == false) {
> +		Time.setTime(Time.getTime() +
> +				gc.get(java.util.Calendar.DST_OFFSET));

Here I think it would be worth double-checking that
gc.getTimeZone().inDaylightTime(Time) has the expected value
(true) after the adjustment, and if not, throwing an exception.

> +	}
> +
> +	// Likewise, if the time is in DST, but should not be, we need to
> +	// subtract the offset.
> +	if (N == 0 && gc.getTimeZone().inDaylightTime(Time) == true) {
> +		Time.setTime(Time.getTime() -
> +				gc.get(java.util.Calendar.DST_OFFSET));

Likewise here.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.
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