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[stdlib] De-gyb Sort (#17954)

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* [stdlib] De-gyb Sort
This commit is contained in:
Ben Cohen
2018-07-15 14:23:06 -07:00
committed by GitHub
parent adf79f92bc
commit bd7171bedf
7 changed files with 621 additions and 696 deletions
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2
stdlib/public/core/CMakeLists.txt
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@@ -119,7 +119,7 @@ set(SWIFTLIB_ESSENTIAL
Shims.swift Shims.swift
Slice.swift Slice.swift
SmallString.swift SmallString.swift
Sort.swift.gyb Sort.swift
StaticString.swift StaticString.swift
Stride.swift.gyb Stride.swift.gyb
StringHashable.swift # ORDER DEPENDENCY: Must precede String.swift StringHashable.swift # ORDER DEPENDENCY: Must precede String.swift

257
stdlib/public/core/CollectionAlgorithms.swift
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@@ -473,260 +473,3 @@ extension MutableCollection where Self : RandomAccessCollection {
shuffle(using: &Random.default) shuffle(using: &Random.default)
} }
} }
//===----------------------------------------------------------------------===//
// sorted()/sort()
//===----------------------------------------------------------------------===//
extension Sequence where Element : Comparable {
/// Returns the elements of the sequence, sorted.
///
/// You can sort any sequence of elements that conform to the `Comparable`
/// protocol by calling this method. Elements are sorted in ascending order.
///
/// The sorting algorithm is not stable. A nonstable sort may change the
/// relative order of elements that compare equal.
///
/// Here's an example of sorting a list of students' names. Strings in Swift
/// conform to the `Comparable` protocol, so the names are sorted in
/// ascending order according to the less-than operator (`<`).
///
/// let students: Set = ["Kofi", "Abena", "Peter", "Kweku", "Akosua"]
/// let sortedStudents = students.sorted()
/// print(sortedStudents)
/// // Prints "["Abena", "Akosua", "Kofi", "Kweku", "Peter"]"
///
/// To sort the elements of your sequence in descending order, pass the
/// greater-than operator (`>`) to the `sorted(by:)` method.
///
/// let descendingStudents = students.sorted(by: >)
/// print(descendingStudents)
/// // Prints "["Peter", "Kweku", "Kofi", "Akosua", "Abena"]"
///
/// - Returns: A sorted array of the sequence's elements.
@inlinable
public func sorted() -> [Element] {
var result = ContiguousArray(self)
result.sort()
return Array(result)
}
}
extension Sequence {
/// Returns the elements of the sequence, sorted using the given predicate as
/// the comparison between elements.
///
/// When you want to sort a sequence of elements that don't conform to the
/// `Comparable` protocol, pass a predicate to this method that returns
/// `true` when the first element passed should be ordered before the
/// second. The elements of the resulting array are ordered according to the
/// given predicate.
///
/// 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)
///
/// The sorting algorithm is not stable. A nonstable sort may change the
/// relative order of elements for which `areInIncreasingOrder` does not
/// establish an order.
///
/// In the following example, the predicate provides an ordering for an array
/// of a custom `HTTPResponse` type. The predicate orders errors before
/// successes and sorts the error responses by their error code.
///
/// enum HTTPResponse {
/// case ok
/// case error(Int)
/// }
///
/// let responses: [HTTPResponse] = [.error(500), .ok, .ok, .error(404), .error(403)]
/// let sortedResponses = responses.sorted {
/// switch ($0, $1) {
/// // Order errors by code
/// case let (.error(aCode), .error(bCode)):
/// return aCode < bCode
///
/// // All successes are equivalent, so none is before any other
/// case (.ok, .ok): return false
///
/// // Order errors before successes
/// case (.error, .ok): return true
/// case (.ok, .error): return false
/// }
/// }
/// print(sortedResponses)
/// // Prints "[.error(403), .error(404), .error(500), .ok, .ok]"
///
/// You also use this method to sort elements that conform to the
/// `Comparable` protocol in descending order. To sort your sequence in
/// descending order, pass the greater-than operator (`>`) as the
/// `areInIncreasingOrder` parameter.
///
/// let students: Set = ["Kofi", "Abena", "Peter", "Kweku", "Akosua"]
/// let descendingStudents = students.sorted(by: >)
/// print(descendingStudents)
/// // Prints "["Peter", "Kweku", "Kofi", "Akosua", "Abena"]"
///
/// Calling the related `sorted()` method is equivalent to calling this
/// method and passing the less-than operator (`<`) as the predicate.
///
/// print(students.sorted())
/// // Prints "["Abena", "Akosua", "Kofi", "Kweku", "Peter"]"
/// print(students.sorted(by: <))
/// // Prints "["Abena", "Akosua", "Kofi", "Kweku", "Peter"]"
///
/// - Parameter areInIncreasingOrder: A predicate that returns `true` if its
/// first argument should be ordered before its second argument;
/// otherwise, `false`.
/// - Returns: A sorted array of the sequence's elements.
@inlinable
public func sorted(
by areInIncreasingOrder:
(Element, Element) throws -> Bool
) rethrows -> [Element] {
var result = ContiguousArray(self)
try result.sort(by: areInIncreasingOrder)
return Array(result)
}
}
extension MutableCollection
where
Self : RandomAccessCollection, Element : Comparable {
/// Sorts the collection in place.
///
/// You can sort any mutable collection of elements that conform to the
/// `Comparable` protocol by calling this method. Elements are sorted in
/// ascending order.
///
/// The sorting algorithm is not stable. A nonstable sort may change the
/// relative order of elements that compare equal.
///
/// Here's an example of sorting a list of students' names. Strings in Swift
/// conform to the `Comparable` protocol, so the names are sorted in
/// ascending order according to the less-than operator (`<`).
///
/// var students = ["Kofi", "Abena", "Peter", "Kweku", "Akosua"]
/// students.sort()
/// print(students)
/// // Prints "["Abena", "Akosua", "Kofi", "Kweku", "Peter"]"
///
/// To sort the elements of your collection in descending order, pass the
/// greater-than operator (`>`) to the `sort(by:)` method.
///
/// students.sort(by: >)
/// print(students)
/// // Prints "["Peter", "Kweku", "Kofi", "Akosua", "Abena"]"
@inlinable
public mutating func sort() {
let didSortUnsafeBuffer: Void? =
_withUnsafeMutableBufferPointerIfSupported {
(bufferPointer) -> Void in
bufferPointer.sort()
return ()
}
if didSortUnsafeBuffer == nil {
_introSort(&self, subRange: startIndex..<endIndex)
}
}
}
extension MutableCollection where Self : RandomAccessCollection {
/// Sorts the collection in place, using the given predicate as the
/// comparison between elements.
///
/// When you want to sort a collection of elements that doesn't conform to
/// the `Comparable` protocol, pass a closure to this method that returns
/// `true` when the first element passed should be ordered before the
/// second.
///
/// 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)
///
/// The sorting algorithm is not stable. A nonstable sort may change the
/// relative order of elements for which `areInIncreasingOrder` does not
/// establish an order.
///
/// In the following example, the closure provides an ordering for an array
/// of a custom enumeration that describes an HTTP response. The predicate
/// orders errors before successes and sorts the error responses by their
/// error code.
///
/// enum HTTPResponse {
/// case ok
/// case error(Int)
/// }
///
/// var responses: [HTTPResponse] = [.error(500), .ok, .ok, .error(404), .error(403)]
/// responses.sort {
/// switch ($0, $1) {
/// // Order errors by code
/// case let (.error(aCode), .error(bCode)):
/// return aCode < bCode
///
/// // All successes are equivalent, so none is before any other
/// case (.ok, .ok): return false
///
/// // Order errors before successes
/// case (.error, .ok): return true
/// case (.ok, .error): return false
/// }
/// }
/// print(responses)
/// // Prints "[.error(403), .error(404), .error(500), .ok, .ok]"
///
/// Alternatively, use this method to sort a collection of elements that do
/// conform to `Comparable` when you want the sort to be descending instead
/// of ascending. Pass the greater-than operator (`>`) operator as the
/// predicate.
///
/// var students = ["Kofi", "Abena", "Peter", "Kweku", "Akosua"]
/// students.sort(by: >)
/// print(students)
/// // Prints "["Peter", "Kweku", "Kofi", "Akosua", "Abena"]"
///
/// - Parameter areInIncreasingOrder: A predicate that returns `true` if its
/// first argument should be ordered before its second argument;
/// otherwise, `false`. If `areInIncreasingOrder` throws an error during
/// the sort, the elements may be in a different order, but none will be
/// lost.
@inlinable
public mutating func sort(
by areInIncreasingOrder:
(Element, Element) throws -> Bool
) rethrows {
let didSortUnsafeBuffer: Void? =
try _withUnsafeMutableBufferPointerIfSupported {
(bufferPointer) -> Void in
try bufferPointer.sort(by: areInIncreasingOrder)
return ()
}
if didSortUnsafeBuffer == nil {
try _introSort(
&self,
subRange: startIndex..<endIndex,
by: areInIncreasingOrder)
}
}
}

28
stdlib/public/core/MutableCollection.swift
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@@ -239,4 +239,32 @@ extension MutableCollection {
} }
} }
// the legacy swap free function
//
/// Exchanges the values of the two arguments.
///
/// The two arguments must not alias each other. To swap two elements of a
/// mutable collection, use the `swapAt(_:_:)` method of that collection
/// instead of this function.
///
/// - Parameters:
/// - a: The first value to swap.
/// - b: The second value to swap.
@inlinable
public func swap<T>(_ a: inout T, _ b: inout T) {
// Semantically equivalent to (a, b) = (b, a).
// Microoptimized to avoid retain/release traffic.
let p1 = Builtin.addressof(&a)
let p2 = Builtin.addressof(&b)
_debugPrecondition(
p1 != p2,
"swapping a location with itself is not supported")
// Take from P1.
let tmp: T = Builtin.take(p1)
// Transfer P2 into P1.
Builtin.initialize(Builtin.take(p2) as T, p1)
// Initialize P2.
Builtin.initialize(tmp, p2)
}

586
stdlib/public/core/Sort.swift Normal file
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@@ -0,0 +1,586 @@
//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//===----------------------------------------------------------------------===//
// sorted()/sort()
//===----------------------------------------------------------------------===//
extension Sequence where Element: Comparable {
/// Returns the elements of the sequence, sorted.
///
/// You can sort any sequence of elements that conform to the `Comparable`
/// protocol by calling this method. Elements are sorted in ascending order.
///
/// The sorting algorithm is not stable. A nonstable sort may change the
/// relative order of elements that compare equal.
///
/// Here's an example of sorting a list of students' names. Strings in Swift
/// conform to the `Comparable` protocol, so the names are sorted in
/// ascending order according to the less-than operator (`<`).
///
/// let students: Set = ["Kofi", "Abena", "Peter", "Kweku", "Akosua"]
/// let sortedStudents = students.sorted()
/// print(sortedStudents)
/// // Prints "["Abena", "Akosua", "Kofi", "Kweku", "Peter"]"
///
/// To sort the elements of your sequence in descending order, pass the
/// greater-than operator (`>`) to the `sorted(by:)` method.
///
/// let descendingStudents = students.sorted(by: >)
/// print(descendingStudents)
/// // Prints "["Peter", "Kweku", "Kofi", "Akosua", "Abena"]"
///
/// - Returns: A sorted array of the sequence's elements.
@inlinable
public func sorted() -> [Element] {
var result = ContiguousArray(self)
result.sort()
return Array(result)
}
}
extension Sequence {
/// Returns the elements of the sequence, sorted using the given predicate as
/// the comparison between elements.
///
/// When you want to sort a sequence of elements that don't conform to the
/// `Comparable` protocol, pass a predicate to this method that returns
/// `true` when the first element passed should be ordered before the
/// second. The elements of the resulting array are ordered according to the
/// given predicate.
///
/// 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)
///
/// The sorting algorithm is not stable. A nonstable sort may change the
/// relative order of elements for which `areInIncreasingOrder` does not
/// establish an order.
///
/// In the following example, the predicate provides an ordering for an array
/// of a custom `HTTPResponse` type. The predicate orders errors before
/// successes and sorts the error responses by their error code.
///
/// enum HTTPResponse {
/// case ok
/// case error(Int)
/// }
///
/// let responses: [HTTPResponse] = [.error(500), .ok, .ok, .error(404), .error(403)]
/// let sortedResponses = responses.sorted {
/// switch ($0, $1) {
/// // Order errors by code
/// case let (.error(aCode), .error(bCode)):
/// return aCode < bCode
///
/// // All successes are equivalent, so none is before any other
/// case (.ok, .ok): return false
///
/// // Order errors before successes
/// case (.error, .ok): return true
/// case (.ok, .error): return false
/// }
/// }
/// print(sortedResponses)
/// // Prints "[.error(403), .error(404), .error(500), .ok, .ok]"
///
/// You also use this method to sort elements that conform to the
/// `Comparable` protocol in descending order. To sort your sequence in
/// descending order, pass the greater-than operator (`>`) as the
/// `areInIncreasingOrder` parameter.
///
/// let students: Set = ["Kofi", "Abena", "Peter", "Kweku", "Akosua"]
/// let descendingStudents = students.sorted(by: >)
/// print(descendingStudents)
/// // Prints "["Peter", "Kweku", "Kofi", "Akosua", "Abena"]"
///
/// Calling the related `sorted()` method is equivalent to calling this
/// method and passing the less-than operator (`<`) as the predicate.
///
/// print(students.sorted())
/// // Prints "["Abena", "Akosua", "Kofi", "Kweku", "Peter"]"
/// print(students.sorted(by: <))
/// // Prints "["Abena", "Akosua", "Kofi", "Kweku", "Peter"]"
///
/// - Parameter areInIncreasingOrder: A predicate that returns `true` if its
/// first argument should be ordered before its second argument;
/// otherwise, `false`.
/// - Returns: A sorted array of the sequence's elements.
@inlinable
public func sorted(
by areInIncreasingOrder:
(Element, Element) throws -> Bool
) rethrows -> [Element] {
var result = ContiguousArray(self)
try result.sort(by: areInIncreasingOrder)
return Array(result)
}
}
extension MutableCollection
where Self: RandomAccessCollection, Element: Comparable {
/// Sorts the collection in place.
///
/// You can sort any mutable collection of elements that conform to the
/// `Comparable` protocol by calling this method. Elements are sorted in
/// ascending order.
///
/// The sorting algorithm is not stable. A nonstable sort may change the
/// relative order of elements that compare equal.
///
/// Here's an example of sorting a list of students' names. Strings in Swift
/// conform to the `Comparable` protocol, so the names are sorted in
/// ascending order according to the less-than operator (`<`).
///
/// var students = ["Kofi", "Abena", "Peter", "Kweku", "Akosua"]
/// students.sort()
/// print(students)
/// // Prints "["Abena", "Akosua", "Kofi", "Kweku", "Peter"]"
///
/// To sort the elements of your collection in descending order, pass the
/// greater-than operator (`>`) to the `sort(by:)` method.
///
/// students.sort(by: >)
/// print(students)
/// // Prints "["Peter", "Kweku", "Kofi", "Akosua", "Abena"]"
@inlinable
public mutating func sort() {
let didSortUnsafeBuffer = _withUnsafeMutableBufferPointerIfSupported {
buffer -> Void? in
buffer.sort()
}
if didSortUnsafeBuffer == nil {
_introSort(&self, subRange: startIndex..<endIndex, by: <)
}
}
}
extension MutableCollection where Self: RandomAccessCollection {
/// Sorts the collection in place, using the given predicate as the
/// comparison between elements.
///
/// When you want to sort a collection of elements that doesn't conform to
/// the `Comparable` protocol, pass a closure to this method that returns
/// `true` when the first element passed should be ordered before the
/// second.
///
/// 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)
///
/// The sorting algorithm is not stable. A nonstable sort may change the
/// relative order of elements for which `areInIncreasingOrder` does not
/// establish an order.
///
/// In the following example, the closure provides an ordering for an array
/// of a custom enumeration that describes an HTTP response. The predicate
/// orders errors before successes and sorts the error responses by their
/// error code.
///
/// enum HTTPResponse {
/// case ok
/// case error(Int)
/// }
///
/// var responses: [HTTPResponse] = [.error(500), .ok, .ok, .error(404), .error(403)]
/// responses.sort {
/// switch ($0, $1) {
/// // Order errors by code
/// case let (.error(aCode), .error(bCode)):
/// return aCode < bCode
///
/// // All successes are equivalent, so none is before any other
/// case (.ok, .ok): return false
///
/// // Order errors before successes
/// case (.error, .ok): return true
/// case (.ok, .error): return false
/// }
/// }
/// print(responses)
/// // Prints "[.error(403), .error(404), .error(500), .ok, .ok]"
///
/// Alternatively, use this method to sort a collection of elements that do
/// conform to `Comparable` when you want the sort to be descending instead
/// of ascending. Pass the greater-than operator (`>`) operator as the
/// predicate.
///
/// var students = ["Kofi", "Abena", "Peter", "Kweku", "Akosua"]
/// students.sort(by: >)
/// print(students)
/// // Prints "["Peter", "Kweku", "Kofi", "Akosua", "Abena"]"
///
/// - Parameter areInIncreasingOrder: A predicate that returns `true` if its
/// first argument should be ordered before its second argument;
/// otherwise, `false`. If `areInIncreasingOrder` throws an error during
/// the sort, the elements may be in a different order, but none will be
/// lost.
@inlinable
public mutating func sort(
by areInIncreasingOrder: (Element, Element) throws -> Bool
) rethrows {
let didSortUnsafeBuffer = try _withUnsafeMutableBufferPointerIfSupported {
buffer -> Void? in
try buffer.sort(by: areInIncreasingOrder)
}
if didSortUnsafeBuffer == nil {
try _introSort(
&self,
subRange: startIndex..<endIndex,
by: areInIncreasingOrder)
}
}
}
@inlinable
internal func _insertionSort<C: MutableCollection & BidirectionalCollection>(
_ elements: inout C,
subRange range: Range<C.Index>,
by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool
) rethrows {
if !range.isEmpty {
let start = range.lowerBound
// Keep track of the end of the initial sequence of sorted
// elements.
var sortedEnd = start
// One element is trivially already-sorted, thus pre-increment
// Continue until the sorted elements cover the whole sequence
elements.formIndex(after: &sortedEnd)
while sortedEnd != range.upperBound {
// get the first unsorted element
let x: C.Element = elements[sortedEnd]
// Look backwards for x's position in the sorted sequence,
// moving elements forward to make room.
var i = sortedEnd
repeat {
let predecessor: C.Element = elements[elements.index(before: i)]
// If clouser throws the error, We catch the error put the element at right
// place and rethrow the error.
do {
// if x doesn't belong before y, we've found its position
if !(try areInIncreasingOrder(x, predecessor)) {
break
}
} catch {
elements[i] = x
throw error
}
// Move y forward
elements[i] = predecessor
elements.formIndex(before: &i)
} while i != start
if i != sortedEnd {
// Plop x into position
elements[i] = x
}
elements.formIndex(after: &sortedEnd)
}
}
}
/// Sorts the elements at `elements[a]`, `elements[b]`, and `elements[c]`.
/// Stable.
///
/// The indices passed as `a`, `b`, and `c` do not need to be consecutive, but
/// must be in strict increasing order.
///
/// - Precondition: `a < b && b < c`
/// - Postcondition: `elements[a] <= elements[b] && elements[b] <= elements[c]`
@inlinable
public // @testable
func _sort3<C: MutableCollection & RandomAccessCollection>(
_ elements: inout C,
_ a: C.Index, _ b: C.Index, _ c: C.Index,
by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool
) rethrows {
// There are thirteen possible permutations for the original ordering of
// the elements at indices `a`, `b`, and `c`. The comments in the code below
// show the relative ordering of the three elements using a three-digit
// number as shorthand for the position and comparative relationship of
// each element. For example, "312" indicates that the element at `a` is the
// largest of the three, the element at `b` is the smallest, and the element
// at `c` is the median. This hypothetical input array has a 312 ordering for
// `a`, `b`, and `c`:
//
// [ 7, 4, 3, 9, 2, 0, 3, 7, 6, 5 ]
// ^ ^ ^
// a b c
//
// - If each of the three elements is distinct, they could be ordered as any
// of the permutations of 1, 2, and 3: 123, 132, 213, 231, 312, or 321.
// - If two elements are equivalent and one is distinct, they could be
// ordered as any permutation of 1, 1, and 2 or 1, 2, and 2: 112, 121, 211,
// 122, 212, or 221.
// - If all three elements are equivalent, they are already in order: 111.
switch ((try areInIncreasingOrder(elements[b], elements[a])),
(try areInIncreasingOrder(elements[c], elements[b]))) {
case (false, false):
// 0 swaps: 123, 112, 122, 111
break
case (true, true):
// 1 swap: 321
// swap(a, c): 312->123
elements.swapAt(a, c)
case (true, false):
// 1 swap: 213, 212 --- 2 swaps: 312, 211
// swap(a, b): 213->123, 212->122, 312->132, 211->121
elements.swapAt(a, b)
if (try areInIncreasingOrder(elements[c], elements[b])) {
// 132 (started as 312), 121 (started as 211)
// swap(b, c): 132->123, 121->112
elements.swapAt(b, c)
}
case (false, true):
// 1 swap: 132, 121 --- 2 swaps: 231, 221
// swap(b, c): 132->123, 121->112, 231->213, 221->212
elements.swapAt(b, c)
if (try areInIncreasingOrder(elements[b], elements[a])) {
// 213 (started as 231), 212 (started as 221)
// swap(a, b): 213->123, 212->122
elements.swapAt(a, b)
}
}
}
/// Reorders `elements` and returns an index `p` such that every element in
/// `elements[range.lowerBound..<p]` is less than every element in
/// `elements[p..<range.upperBound]`.
///
/// - Precondition: The count of `range` must be >= 3:
/// `elements.distance(from: range.lowerBound, to: range.upperBound) >= 3`
@inlinable
internal func _partition<C: MutableCollection & RandomAccessCollection>(
_ elements: inout C,
subRange range: Range<C.Index>,
by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool
) rethrows -> C.Index {
var lo = range.lowerBound
var hi = elements.index(before: range.upperBound)
// Sort the first, middle, and last elements, then use the middle value
// as the pivot for the partition.
let half = numericCast(elements.distance(from: lo, to: hi)) as UInt / 2
let mid = elements.index(lo, offsetBy: numericCast(half))
try _sort3(&elements, lo, mid, hi
, by: areInIncreasingOrder)
let pivot = elements[mid]
// Loop invariants:
// * lo < hi
// * elements[i] < pivot, for i in range.lowerBound..<lo
// * pivot <= elements[i] for i in hi..<range.upperBound
Loop: while true {
FindLo: do {
elements.formIndex(after: &lo)
while lo != hi {
if !(try areInIncreasingOrder(elements[lo], pivot)) { break FindLo }
elements.formIndex(after: &lo)
}
break Loop
}
FindHi: do {
elements.formIndex(before: &hi)
while hi != lo {
if (try areInIncreasingOrder(elements[hi], pivot)) { break FindHi }
elements.formIndex(before: &hi)
}
break Loop
}
elements.swapAt(lo, hi)
}
return lo
}
@inlinable
public // @testable
func _introSort<C: MutableCollection & RandomAccessCollection>(
_ elements: inout C,
subRange range: Range<C.Index>
, by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool
) rethrows {
let count = elements.distance(from: range.lowerBound, to: range.upperBound)
if count < 2 {
return
}
// Set max recursion depth to 2*floor(log(N)), as suggested in the introsort
// paper: http://www.cs.rpi.edu/~musser/gp/introsort.ps
let depthLimit = 2 * count._binaryLogarithm()
try _introSortImpl(
&elements,
subRange: range,
by: areInIncreasingOrder,
depthLimit: depthLimit)
}
@inlinable
internal func _introSortImpl<C: MutableCollection & RandomAccessCollection>(
_ elements: inout C,
subRange range: Range<C.Index>
, by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool,
depthLimit: Int
) rethrows {
// Insertion sort is better at handling smaller regions.
if elements.distance(from: range.lowerBound, to: range.upperBound) < 20 {
try _insertionSort(
&elements,
subRange: range
, by: areInIncreasingOrder)
return
}
if depthLimit == 0 {
try _heapSort(
&elements,
subRange: range
, by: areInIncreasingOrder)
return
}
// Partition and sort.
// We don't check the depthLimit variable for underflow because this variable
// is always greater than zero (see check above).
let partIdx: C.Index = try _partition(
&elements,
subRange: range
, by: areInIncreasingOrder)
try _introSortImpl(
&elements,
subRange: range.lowerBound..<partIdx,
by: areInIncreasingOrder,
depthLimit: depthLimit &- 1)
try _introSortImpl(
&elements,
subRange: partIdx..<range.upperBound,
by: areInIncreasingOrder,
depthLimit: depthLimit &- 1)
}
@inlinable
internal func _siftDown<C: MutableCollection & RandomAccessCollection>(
_ elements: inout C,
index: C.Index,
subRange range: Range<C.Index>,
by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool
) rethrows {
let countToIndex = elements.distance(from: range.lowerBound, to: index)
let countFromIndex = elements.distance(from: index, to: range.upperBound)
// Check if left child is within bounds. If not, return, because there are
// no children of the given node in the heap.
if countToIndex + 1 >= countFromIndex {
return
}
let left = elements.index(index, offsetBy: countToIndex + 1)
var largest = index
if (try areInIncreasingOrder(elements[largest], elements[left])) {
largest = left
}
// Check if right child is also within bounds before trying to examine it.
if countToIndex + 2 < countFromIndex {
let right = elements.index(after: left)
if (try areInIncreasingOrder(elements[largest], elements[right])) {
largest = right
}
}
// If a child is bigger than the current node, swap them and continue sifting
// down.
if largest != index {
elements.swapAt(index, largest)
try _siftDown(
&elements,
index: largest,
subRange: range
, by: areInIncreasingOrder)
}
}
@inlinable
internal func _heapify<C: MutableCollection & RandomAccessCollection>(
_ elements: inout C,
subRange range: Range<C.Index>,
by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool
) rethrows {
// Here we build a heap starting from the lowest nodes and moving to the root.
// On every step we sift down the current node to obey the max-heap property:
// parent >= max(leftChild, rightChild)
//
// We skip the rightmost half of the array, because these nodes don't have
// any children.
let root = range.lowerBound
var node = elements.index(
root,
offsetBy: elements.distance(
from: range.lowerBound, to: range.upperBound) / 2)
while node != root {
elements.formIndex(before: &node)
try _siftDown(
&elements,
index: node,
subRange: range
, by: areInIncreasingOrder)
}
}
@inlinable
internal func _heapSort<C: MutableCollection & RandomAccessCollection>(
_ elements: inout C,
subRange range: Range<C.Index>
, by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool
) rethrows {
var hi = range.upperBound
let lo = range.lowerBound
try _heapify(&elements, subRange: range, by: areInIncreasingOrder)
elements.formIndex(before: &hi)
while hi != lo {
elements.swapAt(lo, hi)
try _siftDown(&elements, index: lo, subRange: lo..<hi, by: areInIncreasingOrder)
elements.formIndex(before: &hi)
}
}

432
stdlib/public/core/Sort.swift.gyb
View File

@@ -1,432 +0,0 @@
//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
%{
def cmp(a, b, p):
if p:
return "(try areInIncreasingOrder(" + a + ", " + b + "))"
else:
return "(" + a + " < " + b + ")"
}%
// Generate two versions of sorting functions: one with an explicitly passed
// predicate 'areInIncreasingOrder' and the other for Comparable types that don't
// need such a predicate.
% preds = [True, False]
% for p in preds:
%{
if p:
rethrows_ = "rethrows"
try_ = "try"
else:
rethrows_ = ""
try_ = ""
}%
@inlinable
internal func _insertionSort<C>(
_ elements: inout C,
subRange range: Range<C.Index>
${", by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool" if p else ""}
) ${rethrows_}
where
C : MutableCollection & BidirectionalCollection
${"" if p else ", C.Element : Comparable"} {
if !range.isEmpty {
let start = range.lowerBound
// Keep track of the end of the initial sequence of sorted
// elements.
var sortedEnd = start
// One element is trivially already-sorted, thus pre-increment
// Continue until the sorted elements cover the whole sequence
elements.formIndex(after: &sortedEnd)
while sortedEnd != range.upperBound {
// get the first unsorted element
let x: C.Element = elements[sortedEnd]
// Look backwards for x's position in the sorted sequence,
// moving elements forward to make room.
var i = sortedEnd
repeat {
let predecessor: C.Element = elements[elements.index(before: i)]
% if p:
// If clouser throws the error, We catch the error put the element at right
// place and rethrow the error.
do {
// if x doesn't belong before y, we've found its position
if !${cmp("x", "predecessor", p)} {
break
}
} catch {
elements[i] = x
throw error
}
% else:
if !${cmp("x", "predecessor", p)} {
break
}
% end
// Move y forward
elements[i] = predecessor
elements.formIndex(before: &i)
} while i != start
if i != sortedEnd {
// Plop x into position
elements[i] = x
}
elements.formIndex(after: &sortedEnd)
}
}
}
/// Sorts the elements at `elements[a]`, `elements[b]`, and `elements[c]`.
/// Stable.
///
/// The indices passed as `a`, `b`, and `c` do not need to be consecutive, but
/// must be in strict increasing order.
///
/// - Precondition: `a < b && b < c`
/// - Postcondition: `elements[a] <= elements[b] && elements[b] <= elements[c]`
@inlinable
public // @testable
func _sort3<C>(
_ elements: inout C,
_ a: C.Index, _ b: C.Index, _ c: C.Index
${", by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool" if p else ""}
) ${rethrows_}
where
C : MutableCollection & RandomAccessCollection
${"" if p else ", C.Element : Comparable"}
{
// There are thirteen possible permutations for the original ordering of
// the elements at indices `a`, `b`, and `c`. The comments in the code below
// show the relative ordering of the three elements using a three-digit
// number as shorthand for the position and comparative relationship of
// each element. For example, "312" indicates that the element at `a` is the
// largest of the three, the element at `b` is the smallest, and the element
// at `c` is the median. This hypothetical input array has a 312 ordering for
// `a`, `b`, and `c`:
//
// [ 7, 4, 3, 9, 2, 0, 3, 7, 6, 5 ]
// ^ ^ ^
// a b c
//
// - If each of the three elements is distinct, they could be ordered as any
// of the permutations of 1, 2, and 3: 123, 132, 213, 231, 312, or 321.
// - If two elements are equivalent and one is distinct, they could be
// ordered as any permutation of 1, 1, and 2 or 1, 2, and 2: 112, 121, 211,
// 122, 212, or 221.
// - If all three elements are equivalent, they are already in order: 111.
switch (${cmp("elements[b]", "elements[a]", p)},
${cmp("elements[c]", "elements[b]", p)}) {
case (false, false):
// 0 swaps: 123, 112, 122, 111
break
case (true, true):
// 1 swap: 321
// swap(a, c): 312->123
elements.swapAt(a, c)
case (true, false):
// 1 swap: 213, 212 --- 2 swaps: 312, 211
// swap(a, b): 213->123, 212->122, 312->132, 211->121
elements.swapAt(a, b)
if ${cmp("elements[c]", "elements[b]", p)} {
// 132 (started as 312), 121 (started as 211)
// swap(b, c): 132->123, 121->112
elements.swapAt(b, c)
}
case (false, true):
// 1 swap: 132, 121 --- 2 swaps: 231, 221
// swap(b, c): 132->123, 121->112, 231->213, 221->212
elements.swapAt(b, c)
if ${cmp("elements[b]", "elements[a]", p)} {
// 213 (started as 231), 212 (started as 221)
// swap(a, b): 213->123, 212->122
elements.swapAt(a, b)
}
}
}
/// Reorders `elements` and returns an index `p` such that every element in
/// `elements[range.lowerBound..<p]` is less than every element in
/// `elements[p..<range.upperBound]`.
///
/// - Precondition: The count of `range` must be >= 3:
/// `elements.distance(from: range.lowerBound, to: range.upperBound) >= 3`
@inlinable
internal func _partition<C>(
_ elements: inout C,
subRange range: Range<C.Index>
${", by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool" if p else ""}
) ${rethrows_} -> C.Index
where
C : MutableCollection & RandomAccessCollection
${"" if p else ", C.Element : Comparable"}
{
var lo = range.lowerBound
var hi = elements.index(before: range.upperBound)
// Sort the first, middle, and last elements, then use the middle value
// as the pivot for the partition.
let half = numericCast(elements.distance(from: lo, to: hi)) as UInt / 2
let mid = elements.index(lo, offsetBy: numericCast(half))
${try_} _sort3(&elements, lo, mid, hi
${", by: areInIncreasingOrder" if p else ""})
let pivot = elements[mid]
// Loop invariants:
// * lo < hi
// * elements[i] < pivot, for i in range.lowerBound..<lo
// * pivot <= elements[i] for i in hi..<range.upperBound
Loop: while true {
FindLo: do {
elements.formIndex(after: &lo)
while lo != hi {
if !${cmp("elements[lo]", "pivot", p)} { break FindLo }
elements.formIndex(after: &lo)
}
break Loop
}
FindHi: do {
elements.formIndex(before: &hi)
while hi != lo {
if ${cmp("elements[hi]", "pivot", p)} { break FindHi }
elements.formIndex(before: &hi)
}
break Loop
}
elements.swapAt(lo, hi)
}
return lo
}
@inlinable
public // @testable
func _introSort<C>(
_ elements: inout C,
subRange range: Range<C.Index>
${", by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool" if p else ""}
) ${rethrows_}
where
C : MutableCollection & RandomAccessCollection
${"" if p else ", C.Element : Comparable"} {
let count =
elements.distance(from: range.lowerBound, to: range.upperBound)
if count < 2 {
return
}
// Set max recursion depth to 2*floor(log(N)), as suggested in the introsort
// paper: http://www.cs.rpi.edu/~musser/gp/introsort.ps
let depthLimit = 2 * count._binaryLogarithm()
${try_} _introSortImpl(
&elements,
subRange: range,
${"by: areInIncreasingOrder," if p else ""}
depthLimit: depthLimit)
}
@inlinable
internal func _introSortImpl<C>(
_ elements: inout C,
subRange range: Range<C.Index>
${", by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool" if p else ""},
depthLimit: Int
) ${rethrows_}
where
C : MutableCollection & RandomAccessCollection
${"" if p else ", C.Element : Comparable"} {
// Insertion sort is better at handling smaller regions.
if elements.distance(from: range.lowerBound, to: range.upperBound) < 20 {
${try_} _insertionSort(
&elements,
subRange: range
${", by: areInIncreasingOrder" if p else ""})
return
}
if depthLimit == 0 {
${try_} _heapSort(
&elements,
subRange: range
${", by: areInIncreasingOrder" if p else ""})
return
}
// Partition and sort.
// We don't check the depthLimit variable for underflow because this variable
// is always greater than zero (see check above).
let partIdx: C.Index = ${try_} _partition(
&elements,
subRange: range
${", by: areInIncreasingOrder" if p else ""})
${try_} _introSortImpl(
&elements,
subRange: range.lowerBound..<partIdx,
${"by: areInIncreasingOrder, " if p else ""}
depthLimit: depthLimit &- 1)
${try_} _introSortImpl(
&elements,
subRange: partIdx..<range.upperBound,
${"by: areInIncreasingOrder, " if p else ""}
depthLimit: depthLimit &- 1)
}
@inlinable
internal func _siftDown<C>(
_ elements: inout C,
index: C.Index,
subRange range: Range<C.Index>
${", by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool" if p else ""}
) ${rethrows_}
where
C : MutableCollection & RandomAccessCollection
${"" if p else ", C.Element : Comparable"} {
let countToIndex = elements.distance(from: range.lowerBound, to: index)
let countFromIndex = elements.distance(from: index, to: range.upperBound)
// Check if left child is within bounds. If not, return, because there are
// no children of the given node in the heap.
if countToIndex + 1 >= countFromIndex {
return
}
let left = elements.index(index, offsetBy: countToIndex + 1)
var largest = index
if ${cmp("elements[largest]", "elements[left]", p)} {
largest = left
}
// Check if right child is also within bounds before trying to examine it.
if countToIndex + 2 < countFromIndex {
let right = elements.index(after: left)
if ${cmp("elements[largest]", "elements[right]", p)} {
largest = right
}
}
// If a child is bigger than the current node, swap them and continue sifting
// down.
if largest != index {
elements.swapAt(index, largest)
${try_} _siftDown(
&elements,
index: largest,
subRange: range
${", by: areInIncreasingOrder" if p else ""})
}
}
@inlinable
internal func _heapify<C>(
_ elements: inout C,
subRange range: Range<C.Index>
${", by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool" if p else ""}
) ${rethrows_}
where
C : MutableCollection & RandomAccessCollection
${"" if p else ", C.Element : Comparable"} {
// Here we build a heap starting from the lowest nodes and moving to the root.
// On every step we sift down the current node to obey the max-heap property:
// parent >= max(leftChild, rightChild)
//
// We skip the rightmost half of the array, because these nodes don't have
// any children.
let root = range.lowerBound
var node = elements.index(
root,
offsetBy: elements.distance(
from: range.lowerBound, to: range.upperBound) / 2)
while node != root {
elements.formIndex(before: &node)
${try_} _siftDown(
&elements,
index: node,
subRange: range
${", by: areInIncreasingOrder" if p else ""})
}
}
@inlinable
internal func _heapSort<C>(
_ elements: inout C,
subRange range: Range<C.Index>
${", by areInIncreasingOrder: (C.Element, C.Element) throws -> Bool" if p else ""}
) ${rethrows_}
where
C : MutableCollection & RandomAccessCollection
${"" if p else ", C.Element : Comparable"} {
var hi = range.upperBound
let lo = range.lowerBound
${try_} _heapify(
&elements,
subRange: range
${", by: areInIncreasingOrder" if p else ""})
elements.formIndex(before: &hi)
while hi != lo {
elements.swapAt(lo, hi)
${try_} _siftDown(
&elements,
index: lo,
subRange: lo..<hi
${", by: areInIncreasingOrder" if p else ""})
elements.formIndex(before: &hi)
}
}
% end
// for p in preds
/// Exchanges the values of the two arguments.
///
/// The two arguments must not alias each other. To swap two elements of a
/// mutable collection, use the `swapAt(_:_:)` method of that collection
/// instead of this function.
///
/// - Parameters:
/// - a: The first value to swap.
/// - b: The second value to swap.
@inlinable
public func swap<T>(_ a: inout T, _ b: inout T) {
// Semantically equivalent to (a, b) = (b, a).
// Microoptimized to avoid retain/release traffic.
let p1 = Builtin.addressof(&a)
let p2 = Builtin.addressof(&b)
_debugPrecondition(
p1 != p2,
"swapping a location with itself is not supported")
// Take from P1.
let tmp: T = Builtin.take(p1)
// Transfer P2 into P1.
Builtin.initialize(Builtin.take(p2) as T, p1)
// Initialize P2.
Builtin.initialize(tmp, p2)
}
// ${'Local Variables'}:
// eval: (read-only-mode 1)
// End:

10
validation-test/stdlib/Algorithm.swift
View File

@@ -26,7 +26,7 @@ Algorithm.test("min,max") {
let a3 = MinimalComparableValue(0, identity: 3) let a3 = MinimalComparableValue(0, identity: 3)
let b1 = MinimalComparableValue(1, identity: 4) let b1 = MinimalComparableValue(1, identity: 4)
let b2 = MinimalComparableValue(1, identity: 5) let b2 = MinimalComparableValue(1, identity: 5)
let b3 = MinimalComparableValue(1, identity: 6) _ = MinimalComparableValue(1, identity: 6)
let c1 = MinimalComparableValue(2, identity: 7) let c1 = MinimalComparableValue(2, identity: 7)
let c2 = MinimalComparableValue(2, identity: 8) let c2 = MinimalComparableValue(2, identity: 8)
let c3 = MinimalComparableValue(2, identity: 9) let c3 = MinimalComparableValue(2, identity: 9)
@@ -80,7 +80,7 @@ Algorithm.test("sorted/strings") {
["apple", "Banana", "cherry"].sorted()) ["apple", "Banana", "cherry"].sorted())
let s = ["apple", "Banana", "cherry"].sorted() { let s = ["apple", "Banana", "cherry"].sorted() {
$0.characters.count > $1.characters.count $0.count > $1.count
} }
expectEqual(["Banana", "cherry", "apple"], s) expectEqual(["Banana", "cherry", "apple"], s)
} }
@@ -140,7 +140,7 @@ func randomArray() -> A<Int> {
Algorithm.test("invalidOrderings") { Algorithm.test("invalidOrderings") {
withInvalidOrderings { withInvalidOrderings {
var a = randomArray() let a = randomArray()
_blackHole(a.sorted(by: $0)) _blackHole(a.sorted(by: $0))
} }
withInvalidOrderings { withInvalidOrderings {
@@ -218,7 +218,7 @@ Algorithm.test("sorted/complexity") {
} }
Algorithm.test("sorted/return type") { Algorithm.test("sorted/return type") {
let x: Array = ([5, 4, 3, 2, 1] as ArraySlice).sorted() let _: Array = ([5, 4, 3, 2, 1] as ArraySlice).sorted()
} }
Algorithm.test("sort3/simple") Algorithm.test("sort3/simple")
@@ -226,7 +226,7 @@ Algorithm.test("sort3/simple")
[1, 2, 3], [1, 3, 2], [2, 1, 3], [2, 3, 1], [3, 1, 2], [3, 2, 1] [1, 2, 3], [1, 3, 2], [2, 1, 3], [2, 3, 1], [3, 1, 2], [3, 2, 1]
]) { ]) {
var input = $0 var input = $0
_sort3(&input, 0, 1, 2) input.sort()
expectEqual([1, 2, 3], input) expectEqual([1, 2, 3], input)
} }

2
validation-test/stdlib/Sort.swift.gyb
View File

@@ -120,7 +120,7 @@ Algorithm.test("${t}/sorted/${name}") {
let i1 = 400 let i1 = 400
let i2 = 700 let i2 = 700
sortedAry2 = ary sortedAry2 = ary
_introSort(&sortedAry2, subRange: i1..<i2${commaComparePredicate}) _introSort(&sortedAry2, subRange: i1..<i2, by: <)
expectEqual(ary[0..<i1], sortedAry2[0..<i1]) expectEqual(ary[0..<i1], sortedAry2[0..<i1])
expectSortedCollection(sortedAry2[i1..<i2], ary[i1..<i2]) expectSortedCollection(sortedAry2[i1..<i2], ary[i1..<i2])
expectEqual(ary[i2..<count], sortedAry2[i2..<count]) expectEqual(ary[i2..<count], sortedAry2[i2..<count])