/// <summary>
/// Determines the intersection of an <see cref="IntervalCollection<T>"/>.
/// </summary>
/// <typeparam name="T">The value type of the intervals.</typeparam>
/// <param name="collection">A collection of <see cref="Interval<T>"/>.</param>
/// <returns>An <see cref="Interval<T>"/> that contains elements belonging to all intervals in the <paramref name="collection"/>.</returns>
/// <exception cref="ArgumentNullException"><paramref name="collection"/> is <c>null</c>.</exception>
internal static Interval <T> IntersectionOf <T>(IntervalCollection <T> collection)
{
if (collection == null)
{
throw new ArgumentNullException("collection");
}
if (collection.Count == 0)
{
return(Interval.Empty <T>());
}
var a = collection[0];
for (int i = 1; i < collection.Count; i++)
{
var b = collection[i];
a = Interval.IntersectionOf(a, b);
}
return(a);
}
/// <summary>
/// Determines the intersection of two intervals.
/// </summary>
/// <typeparam name="T">The value type of the intervals.</typeparam>
/// <param name="a">The first interval.</param>
/// <param name="b">The second interval.</param>
/// <returns>An <see cref="Interval<T>"/> that contains all elements of <paramref name="a"/>
/// that also belong to <paramref name="b"/> (or equivalently, all elements of <paramref name="b"/>
/// that also belong to <paramref name="a"/>), but no other elements.</returns>
/// <seealso href="http://en.wikipedia.org/wiki/Intersection_(set_theory)">Intersection (set theory)</seealso>
private static Interval <T> IntersectionOf <T>(Interval <T> a, Interval <T> b)
{
if (Interval.IsNullOrEmpty(a))
{
return(a);
}
if (Interval.IsNullOrEmpty(b))
{
return(b);
}
var lowestBound = Bound.Min(a.LowerBound, b.LowerBound);
var upmostValue = Bound.Max(a.UpperBound, b.UpperBound);
var lowerBound = default(Bound <T>);
var upperBound = default(Bound <T>);
// a
//-------------
// b
// ---------
if (object.Equals(lowestBound, a.LowerBound) &&
object.Equals(upmostValue, a.UpperBound))
{
lowerBound = new Bound <T>(BoundType.Lower
, object.Equals(a.LowerBound.Value, b.LowerBound.Value)
? Bound.Min(a.LowerBound.Direction, b.LowerBound.Direction)
: b.LowerBound.Direction
, b.LowerBound.Value);
upperBound = new Bound <T>(BoundType.Upper
, object.Equals(a.UpperBound.Value, b.UpperBound.Value)
? Bound.Min(a.UpperBound.Direction, b.UpperBound.Direction)
: b.UpperBound.Direction
, b.UpperBound.Value);
}
// a
// ---------
// b
//-------------
else if (object.Equals(lowestBound, b.LowerBound) &&
object.Equals(upmostValue, b.UpperBound))
{
lowerBound = new Bound <T>(BoundType.Lower
, object.Equals(a.LowerBound.Value, b.LowerBound.Value)
? Bound.Min(a.LowerBound.Direction, b.LowerBound.Direction)
: a.LowerBound.Direction
, a.LowerBound.Value);
upperBound = new Bound <T>(BoundType.Upper
, object.Equals(a.UpperBound.Value, b.UpperBound.Value)
? Bound.Min(a.UpperBound.Direction, b.UpperBound.Direction)
: a.UpperBound.Direction
, a.UpperBound.Value);
}
// a
//---------
// b
// -------------
else if (object.Equals(lowestBound, a.LowerBound) &&
object.Equals(upmostValue, b.UpperBound))
{
lowerBound = new Bound <T>(BoundType.Lower
, object.Equals(a.LowerBound.Value, b.LowerBound.Value)
? Bound.Min(a.LowerBound.Direction, b.LowerBound.Direction)
: b.LowerBound.Direction
, b.LowerBound.Value);
upperBound = new Bound <T>(BoundType.Upper
, object.Equals(a.UpperBound.Value, b.UpperBound.Value)
? Bound.Min(a.UpperBound.Direction, b.UpperBound.Direction)
: a.UpperBound.Direction
, a.UpperBound.Value);
}
// a
// -------------
// b
//---------
else if (object.Equals(lowestBound, b.LowerBound) &&
object.Equals(upmostValue, a.UpperBound))
{
lowerBound = new Bound <T>(BoundType.Lower
, object.Equals(a.LowerBound.Value, b.LowerBound.Value)
? Bound.Min(a.LowerBound.Direction, b.LowerBound.Direction)
: a.LowerBound.Direction
, a.LowerBound.Value);
upperBound = new Bound <T>(BoundType.Upper
, object.Equals(a.UpperBound.Value, b.UpperBound.Value)
? Bound.Min(a.UpperBound.Direction, b.UpperBound.Direction)
: b.UpperBound.Direction
, b.UpperBound.Value);
}
else
{
return(Interval.Empty <T>());
}
Interval <T> result;
return(TryParse(lowerBound, upperBound, out result)
? result
: Interval.Empty <T>());
}