spire.optional.intervalSubsetPartialOrder.scala Maven / Gradle / Ivy

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package spire
package optional

import spire.algebra.{Order, PartialOrder}
import spire.math.Interval

object intervalSubsetPartialOrder {

  /** Interval partial order defined as follows:
   *
   * I <= J if I is a subset of J.
   */
  class IntervalSubsetPartialOrder[A: Order] extends PartialOrder[Interval[A]] {
    override def eqv(x: Interval[A], y: Interval[A]): Boolean = (x == y)
    override def lteqv(x: Interval[A], y: Interval[A]): Boolean = x.isSubsetOf(y)
    override def lt(x: Interval[A], y: Interval[A]): Boolean = x.isProperSubsetOf(y)
    override def gteqv(x: Interval[A], y: Interval[A]): Boolean = x.isSupersetOf(y)
    override def gt(x: Interval[A], y: Interval[A]): Boolean = x.isProperSupersetOf(y)

    def partialCompare(x: Interval[A], y: Interval[A]): Double = {
      if (eqv(x, y)) 0.0
      else if (lt(x, y)) -1.0
      else if (gt(x, y)) 1.0
      else Double.NaN
    }
  }
  implicit def intervalSubsetPartialOrder[A: Order]: PartialOrder[Interval[A]] = new IntervalSubsetPartialOrder[A]
}