protocol RandomAccessIndexType
Inheritance 
BidirectionalIndexType, Comparable, Equatable, ForwardIndexType, Strideable, _Incrementable, _RandomAccessAmbiguity
View Protocol Hierarchy →


Associated Types 
Distance : _SignedIntegerType = Int
A type that can represent the number of steps between pairs of
Reachability is defined by the ability to produce one value from
the other via zero or more applications of Stride : SignedNumberType
A type that can represent the distance between two values of 
Import  import Swift 
Instance Methods
A strict total order
over instances of Self
.
Declaration
func <(lhs: Self, rhs: Self) > Bool
Declared In
Comparable
Returns 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 tripleequals ===
is notably not part of an instance's value. Exposing other
nonvalue 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
istrue
x == y
impliesy == x
x == y
andy == z
impliesx == z
Inequality is the inverse of equality, i.e. !(x == y)
iff
x != y
.
Declaration
func ==(lhs: Self, rhs: Self) > Bool
Declared In
Equatable
Declaration
func advancedBy(n: Self.Distance) > Self
Declared In
RandomAccessIndexType
, ForwardIndexType
, Strideable
Declaration
func advancedBy(n: Self.Distance, limit: Self) > Self
Declared In
RandomAccessIndexType
, ForwardIndexType
Declaration
func distanceTo(other: Self) > Self.Distance
Declared In
RandomAccessIndexType
, ForwardIndexType
, Strideable
Returns the previous consecutive value in a discrete sequence.
If self
has a welldefined successor,
self.successor().predecessor() == self
. If self
has a
welldefined predecessor, self.predecessor().successor() ==
self
.
Requires: self
has a welldefined predecessor.
Declaration
func predecessor() > Self
Declared In
BidirectionalIndexType
Returns the next consecutive value in a discrete sequence of
Self
values.
Requires: self
has a welldefined successor.
Declaration
func successor() > Self
Declared In
_Incrementable
Default Implementations
Returns the result of advancing self
by n
positions.
Returns:
 If n > 0
, the result of applying successor
to self
n
times.
 If n < 0
, the result of applying predecessor
to self
n
times.
 Otherwise, self
.
Requires: n >= 0
if only conforming to ForwardIndexType
Complexity:
 O(1) if conforming to RandomAccessIndexType
 O(abs(n)
) otherwise
Declaration
func advancedBy(n: Self.Distance) > Self
Declared In
BidirectionalIndexType
, _RandomAccessAmbiguity
, ForwardIndexType
Declaration
func advancedBy(n: Self.Distance, limit: Self) > Self
Declared In
RandomAccessIndexType
, BidirectionalIndexType
, ForwardIndexType
Measure the distance between self
and end
.
Requires:
 start
and end
are part of the same sequence when conforming to
RandomAccessSequenceType
.
 end
is reachable from self
by incrementation otherwise.
Complexity:
 O(1) if conforming to RandomAccessIndexType
 O(n
) otherwise, where n
is the function's result.
Declaration
func distanceTo(end: Self) > Self.Distance
Declared In
BidirectionalIndexType
, ForwardIndexType
Returns the sequence of values (self
, self + stride
, self +
stride + stride
, ... last) where last is the last value in
the progression less than or equal to end
.
Note: There is no guarantee that end
is an element of the sequence.
Declaration
func stride(through end: Self, by stride: Self.Stride) > StrideThrough<Self>
Declared In
Strideable
Returns the sequence of values (self
, self + stride
, self +
stride + stride
, ... last) where last is the last value in
the progression that is less than end
.
Declaration
func stride(to end: Self, by stride: Self.Stride) > StrideTo<Self>
Declared In
Strideable
An index that can be offset by an arbitrary number of positions, and can measure the distance to any reachable value, in O(1).