/**
* Calculates the amount of time until another year in terms of the specified unit.
* <p>
* This calculates the amount of time between two {@code Year}
* objects in terms of a single {@code TemporalUnit}.
* The start and end points are {@code this} and the specified year.
* The result will be negative if the end is before the start.
* The {@code Temporal} passed to this method is converted to a
* {@code Year} using {@link #from(TemporalAccessor)}.
* For example, the amount in decades between two year can be calculated
* using {@code startYear.until(endYear, DECADES)}.
* <p>
* The calculation returns a whole number, representing the number of
* complete units between the two years.
* For example, the amount in decades between 2012 and 2031
* will only be one decade as it is one year short of two decades.
* <p>
* There are two equivalent ways of using this method.
* The first is to invoke this method.
* The second is to use {@link TemporalUnit#between(Temporal, Temporal)}:
* <pre>
* // these two lines are equivalent
* amount = start.until(end, YEARS);
* amount = YEARS.between(start, end);
* </pre>
* The choice should be made based on which makes the code more readable.
* <p>
* The calculation is implemented in this method for {@link ChronoUnit}.
* The units {@code YEARS}, {@code DECADES}, {@code CENTURIES},
* {@code MILLENNIA} and {@code ERAS} are supported.
* Other {@code ChronoUnit} values will throw an exception.
* <p>
* If the unit is not a {@code ChronoUnit}, then the result of this method
* is obtained by invoking {@code TemporalUnit.between(Temporal, Temporal)}
* passing {@code this} as the first argument and the converted input temporal
* as the second argument.
* <p>
* This instance is immutable and unaffected by this method call.
*
* @param Temporal $endExclusive the end date, exclusive, which is converted to a {@code Year}, not null
* @param TemporalUnit $unit the unit to measure the amount in, not null
* @return int the amount of time between this year and the end year
* @throws DateTimeException if the amount cannot be calculated, or the end
* temporal cannot be converted to a {@code Year}
* @throws UnsupportedTemporalTypeException if the unit is not supported
* @throws ArithmeticException if numeric overflow occurs
*/
public function until(Temporal $endExclusive, TemporalUnit $unit)
{
$end = Year::from($endExclusive);
if ($unit instanceof ChronoUnit) {
$yearsUntil = $end->year - $this->year;
// no overflow
switch ($unit) {
case ChronoUnit::YEARS():
return $yearsUntil;
case ChronoUnit::DECADES():
return Math::div($yearsUntil, 10);
case ChronoUnit::CENTURIES():
return Math::div($yearsUntil, 100);
case ChronoUnit::MILLENNIA():
return Math::div($yearsUntil, 1000);
case ChronoUnit::ERAS():
return $end->getLong(ChronoField::ERA()) - $this->getLong(ChronoField::ERA());
}
throw new UnsupportedTemporalTypeException("Unsupported unit: " . $unit);
}
return $unit->between($this, $end);
}
public function test_from_TemporalAccessor_null()
{
TestHelper::assertNullException($this, function () {
Year::from(null);
});
}
