Instance MethodSwift

lexicographicallyPrecedes(_:by:)

Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the given predicate to compare elements.

func lexicographicallyPrecedes<OtherSequence>(_ other: OtherSequence, by areInIncreasingOrder: (Self.Element, Self.Element) throws -> Bool) rethrows -> Bool where OtherSequence : Sequence, Self.Element == OtherSequence.Element

Parameters

other

A sequence to compare to this sequence.

areinincreasingorder

A predicate that returns true if its first argument should be ordered before its second argument; otherwise, false.

Returns

true if this sequence precedes other in a dictionary ordering as ordered by areInIncreasingOrder; otherwise, false.

Overview

The predicate must be a strict weak ordering over the elements. That is, for any elements a, b, and c, the following conditions must hold:

  • areInIncreasingOrder(a, a) is always false. (Irreflexivity)

  • If areInIncreasingOrder(a, b) and areInIncreasingOrder(b, c) are both true, then areInIncreasingOrder(a, c) is also true. (Transitive comparability)

  • Two elements are incomparable if neither is ordered before the other according to the predicate. If a and b are incomparable, and b and c are incomparable, then a and c are also incomparable. (Transitive incomparability)