protocolStrideable
| Inheritance |
Comparable, Equatable
View Protocol Hierarchy →
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| Associated Types |
A type that represents the distance between two values. |
| Import |
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Instance Methods
Returns a Boolean value indicating whether the value of the first argument is less than that of the second argument.
This function is the only requirement of the Comparable protocol. The
remainder of the relational operator functions are implemented by the
standard library for any type that conforms to Comparable.
Parameters: lhs: A value to compare. rhs: Another value to compare.
Declaration
func<(lhs:Self,rhs:Self) ->Bool
Declared In
Comparable
Returns a Boolean value indicating whether the value of the first argument is less than or equal to that of the second argument.
Parameters: lhs: A value to compare. rhs: Another value to compare.
Declaration
func<=(lhs:Self,rhs:Self) ->Bool
Declared In
Comparable
Returns a Boolean value indicating whether two values are equal.
Equality is the inverse of inequality. For any values a and b,
a == b implies that a != b is false.
Parameters: lhs: A value to compare. rhs: Another value to compare.
Declaration
func==(lhs:Self,rhs:Self) ->Bool
Declared In
Equatable
Returns a Boolean value indicating whether the value of the first argument is greater than that of the second argument.
Parameters: lhs: A value to compare. rhs: Another value to compare.
Declaration
func>(lhs:Self,rhs:Self) ->Bool
Declared In
Comparable
Returns a Boolean value indicating whether the value of the first argument is greater than or equal to that of the second argument.
Parameters: lhs: A value to compare. rhs: Another value to compare.
Declaration
func>=(lhs:Self,rhs:Self) ->Bool
Declared In
Comparable
Returns a value that is offset the specified distance from this value.
Use the advanced(by:) method in generic code to offset a value by a
specified distance. If you're working directly with numeric values, use
the addition operator (+) instead of this method.
funcaddOne<T:Strideable>(tox:T) ->TwhereT.Stride:ExpressibleByIntegerLiteral{returnx.advanced(by:1)}letx=addOne(to:5)// x == 6lety=addOne(to:3.5)// y = 4.5
If this type's Stride type conforms to BinaryInteger, then for a
value x, a distance n, and a value y = x.advanced(by: n),
x.distance(to: y) == n. Using this method with types that have a
noninteger Stride may result in an approximation.
n: The distance to advance this value.
Returns: A value that is offset from this value by n.
Complexity: O(1)
Declaration
funcadvanced(byn:Self.Stride) ->Self
Returns the distance from this value to the given value, expressed as a stride.
If this type's Stride type conforms to BinaryInteger, then for two
values x and y, and a distance n = x.distance(to: y),
x.advanced(by: n) == y. Using this method with types that have a
noninteger Stride may result in an approximation.
other: The value to calculate the distance to.
Returns: The distance from this value to other.
Complexity: O(1)
Declaration
funcdistance(toother:Self) ->Self.Stride
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Default Implementations
Returns a Boolean value indicating whether two values are not equal.
Inequality is the inverse of equality. For any values a and b, a != b
implies that a == b is false.
This is the default implementation of the not-equal-to operator (!=)
for any type that conforms to Equatable.
Parameters: lhs: A value to compare. rhs: Another value to compare.
Declaration
func!=(lhs:Self,rhs:Self) ->Bool
Declared In
Comparable, Equatable
Declaration
func+(lhs:Self,rhs:Self.Stride) ->Self
Declaration
func+(lhs:Self.Stride,rhs:Self) ->Self
Declaration
func+=(lhs:inoutSelf,rhs:Self.Stride)
Returns a partial range up to, and including, its upper bound.
Use the prefix closed range operator (prefix ...) to create a partial
range of any type that conforms to the Comparable protocol. This
example creates a PartialRangeThrough<Double> instance that includes
any value less than or equal to 5.0.
letthroughFive= ...5.0throughFive.contains(4.0)// truethroughFive.contains(5.0)// truethroughFive.contains(6.0)// false
You can use this type of partial range of a collection's indices to represent the range from the start of the collection up to, and including, the partial range's upper bound.
letnumbers= [10,20,30,40,50,60,70](numbers[...3])// Prints "[10, 20, 30, 40]"
maximum: The upper bound for the range.
Declaration
prefixfunc...(maximum:Self) ->PartialRangeThrough<Self>
Declared In
Comparable
Returns a closed range that contains both of its bounds.
Use the closed range operator (...) to create a closed range of any type
that conforms to the Comparable protocol. This example creates a
ClosedRange<Character> from "a" up to, and including, "z".
letlowercase="a"..."z"(lowercase.contains("z"))// Prints "true"
Parameters: minimum: The lower bound for the range. maximum: The upper bound for the range.
Declaration
func...(minimum:Self,maximum:Self) ->ClosedRange<Self>
Declared In
Comparable
Returns a partial range up to, but not including, its upper bound.
Use the prefix half-open range operator (prefix ..<) to create a
partial range of any type that conforms to the Comparable protocol.
This example creates a PartialRangeUpTo<Double> instance that includes
any value less than 5.0.
letupToFive= ..<5.0upToFive.contains(3.14)// trueupToFive.contains(6.28)// falseupToFive.contains(5.0)// false
You can use this type of partial range of a collection's indices to represent the range from the start of the collection up to, but not including, the partial range's upper bound.
letnumbers= [10,20,30,40,50,60,70](numbers[..<3])// Prints "[10, 20, 30]"
maximum: The upper bound for the range.
Declaration
prefixfunc..<(maximum:Self) ->PartialRangeUpTo<Self>
Declared In
Comparable
Returns a half-open range that contains its lower bound but not its upper bound.
Use the half-open range operator (..<) to create a range of any type
that conforms to the Comparable protocol. This example creates a
Range<Double> from zero up to, but not including, 5.0.
letlessThanFive=0.0..<5.0(lessThanFive.contains(3.14))// Prints "true"(lessThanFive.contains(5.0))// Prints "false"
Parameters: minimum: The lower bound for the range. maximum: The upper bound for the range.
Declaration
func..<(minimum:Self,maximum:Self) ->Range<Self>
Declared In
Comparable
Declaration
func<(x:Self,y:Self) ->Bool
Returns a Boolean value indicating whether the value of the first argument is less than or equal to that of the second argument.
This is the default implementation of the less-than-or-equal-to
operator (<=) for any type that conforms to Comparable.
Parameters: lhs: A value to compare. rhs: Another value to compare.
Declaration
func<=(lhs:Self,rhs:Self) ->Bool
Declared In
Comparable
Declaration
func==(x:Self,y:Self) ->Bool
Returns a Boolean value indicating whether the value of the first argument is greater than that of the second argument.
This is the default implementation of the greater-than operator (>) for
any type that conforms to Comparable.
Parameters: lhs: A value to compare. rhs: Another value to compare.
Declaration
func>(lhs:Self,rhs:Self) ->Bool
Declared In
Comparable
Returns a Boolean value indicating whether the value of the first argument is greater than or equal to that of the second argument.
This is the default implementation of the greater-than-or-equal-to operator
(>=) for any type that conforms to Comparable.
Parameters:
lhs: A value to compare.
rhs: Another value to compare.
Returns: true if lhs is greater than or equal to rhs; otherwise,
false.
Declaration
func>=(lhs:Self,rhs:Self) ->Bool
Declared In
Comparable
Declaration
func-(lhs:Self,rhs:Self) ->Self.Stride
Declaration
func-(lhs:Self,rhs:Self.Stride) ->Self
Declaration
func-=(lhs:inoutSelf,rhs:Self.Stride)
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Where Stride : SignedInteger
Returns a countable closed range that contains both of its bounds.
Use the closed range operator (...) to create a closed range of any type
that conforms to the Strideable protocol with an associated signed
integer Stride type, such as any of the standard library's integer
types. This example creates a ClosedRange<Int> from zero up to,
and including, nine.
letsingleDigits=0...9(singleDigits.contains(9))// Prints "true"
You can use sequence or collection methods on the singleDigits range.
(singleDigits.count)// Prints "10"(singleDigits.last)// Prints "9"
Parameters:)`. minimum: The lower bound for the range. maximum: The upper bound for the range.
Declaration
func...(minimum:Self,maximum:Self) ->ClosedRange<Self>
A type representing continuous, one-dimensional values that can be offset and measured.
You can use a type that conforms to the
Strideableprotocol with thestride(from:to:by:)andstride(from:through:by:)functions. For example, you can usestride(from:to:by:)to iterate over an interval of floating-point values:The last parameter of these functions is of the associated
Stridetype---the type that represents the distance between any two instances of theStrideabletype.Types that have an integer
Stridecan be used as the boundaries of a countable range or as the lower bound of an iterable one-sided range. For example, you can iterate over a range ofIntand use sequence and collection methods.Conforming to the Strideable Protocol
To add
Strideableconformance to a custom type, choose aStridetype that can represent the distance between two instances and implement theadvanced(by:)anddistance(to:)methods. For example, this hypotheticalDatetype stores its value as the number of days before or after January 1, 2000:The
Stridetype forDateisInt, inferred from the parameter and return types ofadvanced(by:)anddistance(to:):The
Datetype can now be used with thestride(from:to:by:)andstride(from:through:by:)functions and as the bounds of an iterable range.Important: The
Strideableprotocol provides default implementations for the equal-to (==) and less-than (<) operators that depend on theStridetype's implementations. If a type conforming toStrideableis its ownStridetype, it must provide concrete implementations of the two operators to avoid infinite recursion.