BidirectionalIndexType

protocol BidirectionalIndexType

An index that can step backwards via application of its predecessor() method.

Inheritance Equatable, ForwardIndexType, _BidirectionalIndexType, _ForwardIndexType, _Incrementable View Protocol Hierarchy →
Associated Types
Distance : _SignedIntegerType = Int

A type that can represent the number of steps between pairs of Self values where one value is reachable from the other.

Reachability is defined by the ability to produce one value from the other via zero or more applications of successor.

_DisabledRangeIndex = _DisabledRangeIndex_

A type that can represent the number of steps between pairs of Self values where one value is reachable from the other.

Reachability is defined by the ability to produce one value from the other via zero or more applications of successor.
Import import Swift

Instance Methods

func ==(_:rhs:) Required

Return true if lhs is equal to rhs.

Equality implies substitutability. When x == y, x and y are interchangeable in any code that only depends on their values.

Class instance identity as distinguished by triple-equals === is notably not part of an instance's value. Exposing other non-value aspects of Equatable types is discouraged, and any that are exposed should be explicitly pointed out in documentation.

Equality is an equivalence relation

  • x == x is true
  • x == y implies y == x
  • x == y and y == z implies x == z

Inequality is the inverse of equality, i.e. !(x == y) iff x != y

Declaration

func ==(lhs: Self, rhs: Self) -> Bool

Declared In

Equatable
func predecessor() Required

Return the previous consecutive value in a discrete sequence.

If self has a well-defined successor, self.successor().predecessor() == self. If self has a well-defined predecessor, self.predecessor().successor() == self.

Requires: self has a well-defined predecessor.

Declaration

func predecessor() -> Self

Declared In

_BidirectionalIndexType
func successor() Required

Return the next consecutive value in a discrete sequence of Self values

Requires: self has a well-defined successor.

Declaration

func successor() -> Self

Declared In

_Incrementable