Trait Ordering.OptionOrdering

trait OptionOrdering[T] extends Ordering[Option[T]]

Inherited classlikes

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class OrderingOps(lhs: T)

This inner class defines comparison operators available for T.

It can't extend AnyVal because it is not a top-level class or a member of a statically accessible object.

Abstract methods

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def optionOrdering: Ordering[T]

Concrete methods

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def compare(x: Option[T], y: Option[T]): Int

Returns an integer whose sign communicates how x compares to y.

The result sign has the following meaning:

- negative if x < y - positive if x > y - zero otherwise (if x == y)

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override def equals(obj: Any): Boolean

Compares the receiver object (this) with the argument object (that) for equivalence.

Any implementation of this method should be an equivalence relation:

- It is reflexive: for any instance x of type Any, x.equals(x) should return true. - It is symmetric: for any instances x and y of type Any, x.equals(y) should return true if and only if y.equals(x) returns true. - It is transitive: for any instances x, y, and z of type Any if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.

If you override this method, you should verify that your implementation remains an equivalence relation. Additionally, when overriding this method it is usually necessary to override hashCode to ensure that objects which are "equal" (o1.equals(o2) returns true) hash to the same scala.Int. (o1.hashCode.equals(o2.hashCode)).

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override def hashCode(): Int

Calculate a hash code value for the object.

The default hashing algorithm is platform dependent.

Note that it is allowed for two objects to have identical hash codes (o1.hashCode.equals(o2.hashCode)) yet not be equal (o1.equals(o2) returns false). A degenerate implementation could always return 0. However, it is required that if two objects are equal (o1.equals(o2) returns true) that they have identical hash codes (o1.hashCode.equals(o2.hashCode)). Therefore, when overriding this method, be sure to verify that the behavior is consistent with the equals method.

Inherited methods

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override def equiv(x: Option[T], y: Option[T]): Boolean

Return true if x == y in the ordering.

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override def gt(x: Option[T], y: Option[T]): Boolean

Return true if x > y in the ordering.

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override def gteq(x: Option[T], y: Option[T]): Boolean

Return true if x >= y in the ordering.

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def isReverseOf(other: Ordering[_]): Boolean

Returns whether or not the other ordering is the opposite ordering of this one.

Equivalent to other == this.reverse.

Implementations should only override this method if they are overriding reverse as well.

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override def lt(x: Option[T], y: Option[T]): Boolean

Return true if x < y in the ordering.

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override def lteq(x: Option[T], y: Option[T]): Boolean

Return true if x <= y in the ordering.

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def max[U <: Option[T]](x: U, y: U): U

Return x if x >= y, otherwise y.

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def min[U <: Option[T]](x: U, y: U): U

Return x if x <= y, otherwise y.

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def on[U](f: U => Option[T]): Ordering[U]

Given f, a function from U into T, creates an Ordering[U] whose compare function is equivalent to:

def compare(x:U, y:U) = Ordering[T].compare(f(x), f(y))

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def orElse(other: Ordering[Option[T]]): Ordering[T]

Creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else the result of others compare function.

case class Pair(a: Int, b: Int)
val pairOrdering = Ordering.by[Pair, Int](_.a)
                          .orElse(Ordering.by[Pair, Int](_.b))

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def orElseBy[S](f: Option[T] => S)(implicit ord: Ordering[S]): Ordering[T]

Given f, a function from T into S, creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else a result equivalent to:

Ordering[S].compare(f(x), f(y))

This function is equivalent to passing the result of Ordering.by(f) to orElse.

case class Pair(a: Int, b: Int)
val pairOrdering = Ordering.by[Pair, Int](_.a)
                          .orElseBy[Int](_.b)

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override def reverse: Ordering[T]

Return the opposite ordering of this one.

Implementations overriding this method MUST override isReverseOf as well if they change the behavior at all (for example, caching does not require overriding it).

def reversed(): Comparator[T]

def thenComparing[U <: Comparable[_ >: U <: <FromJavaObject>]](x$0: Function[_ >: Option[T] <: <FromJavaObject>, _ <: U]): Comparator[T]

def thenComparing[U <: <FromJavaObject>](x$0: Function[_ >: Option[T] <: <FromJavaObject>, _ <: U], x$1: Comparator[_ >: U <: <FromJavaObject>]): Comparator[T]

def thenComparing(x$0: Comparator[_ >: Option[T] <: <FromJavaObject>]): Comparator[T]

def thenComparingDouble(x$0: ToDoubleFunction[_ >: Option[T] <: <FromJavaObject>]): Comparator[T]

def thenComparingInt(x$0: ToIntFunction[_ >: Option[T] <: <FromJavaObject>]): Comparator[T]

def thenComparingLong(x$0: ToLongFunction[_ >: Option[T] <: <FromJavaObject>]): Comparator[T]

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def tryCompare(x: Option[T], y: Option[T]): Option[Int]

Returns whether a comparison between x and y is defined, and if so the result of compare(x, y).

Inherited implicits

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implicit def mkOrderingOps(lhs: Option[T]): OrderingOps

This implicit method augments T with the comparison operators defined in scala.math.Ordering.Ops.