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Conditionally conform EnumeratedSequence to Collections
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-89
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5 files changed

+314
-89
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‎stdlib/public/core/Algorithm.swift

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@@ -74,91 +74,3 @@ public func max<T: Comparable>(_ x: T, _ y: T, _ z: T, _ rest: T...) -> T {
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}
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return maxValue
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}
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/// An enumeration of the elements of a sequence or collection.
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///
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/// `EnumeratedSequence` is a sequence of pairs (*n*, *x*), where *n*s are
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/// consecutive `Int` values starting at zero, and *x*s are the elements of a
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/// base sequence.
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///
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/// To create an instance of `EnumeratedSequence`, call `enumerated()` on a
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/// sequence or collection. The following example enumerates the elements of
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/// an array.
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///
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/// var s = ["foo", "bar"].enumerated()
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/// for (n, x) in s {
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/// print("\(n): \(x)")
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/// }
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/// // Prints "0: foo"
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/// // Prints "1: bar"
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@frozen
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public struct EnumeratedSequence<Base: Sequence> {
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@usableFromInline
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internal var _base: Base
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/// Construct from a `Base` sequence.
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@inlinable
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internal init(_base: Base) {
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self._base = _base
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}
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}
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extension EnumeratedSequence: Sendable where Base: Sendable {}
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extension EnumeratedSequence {
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/// The iterator for `EnumeratedSequence`.
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///
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/// An instance of this iterator wraps a base iterator and yields
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/// successive `Int` values, starting at zero, along with the elements of the
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/// underlying base iterator. The following example enumerates the elements of
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/// an array:
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///
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/// var iterator = ["foo", "bar"].enumerated().makeIterator()
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/// iterator.next() // (0, "foo")
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/// iterator.next() // (1, "bar")
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/// iterator.next() // nil
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///
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/// To create an instance, call
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/// `enumerated().makeIterator()` on a sequence or collection.
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@frozen
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public struct Iterator {
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@usableFromInline
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internal var _base: Base.Iterator
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@usableFromInline
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internal var _count: Int
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/// Construct from a `Base` iterator.
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@inlinable
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internal init(_base: Base.Iterator) {
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self._base = _base
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self._count = 0
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}
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}
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}
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extension EnumeratedSequence.Iterator: Sendable where Base.Iterator: Sendable {}
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extension EnumeratedSequence.Iterator: IteratorProtocol, Sequence {
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/// The type of element returned by `next()`.
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public typealias Element = (offset: Int, element: Base.Element)
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/// Advances to the next element and returns it, or `nil` if no next element
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/// exists.
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///
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/// Once `nil` has been returned, all subsequent calls return `nil`.
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@inlinable
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public mutating func next() -> Element? {
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guard let b = _base.next() else { return nil }
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let result = (offset: _count, element: b)
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_count += 1
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return result
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}
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}
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extension EnumeratedSequence: Sequence {
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/// Returns an iterator over the elements of this sequence.
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@inlinable
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public __consuming func makeIterator() -> Iterator {
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return Iterator(_base: _base.makeIterator())
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}
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}

‎stdlib/public/core/CMakeLists.txt

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@@ -75,6 +75,7 @@ split_embedded_sources(
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EMBEDDED DropWhile.swift
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NORMAL Dump.swift
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EMBEDDED EmptyCollection.swift
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EMBEDDED EnumeratedSequence.swift
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EMBEDDED Equatable.swift
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EMBEDDED ErrorType.swift
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EMBEDDED ExistentialCollection.swift

‎stdlib/public/core/EnumeratedSequence.swift

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//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2024 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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/// An enumeration of the elements of a sequence or collection.
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///
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/// `EnumeratedSequence` is a sequence of pairs (*n*, *x*), where *n*s are
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/// consecutive `Int` values starting at zero, and *x*s are the elements of a
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/// base sequence.
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///
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/// To create an instance of `EnumeratedSequence`, call `enumerated()` on a
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/// sequence or collection. The following example enumerates the elements of
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/// an array.
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///
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/// var s = ["foo", "bar"].enumerated()
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/// for (n, x) in s {
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/// print("\(n): \(x)")
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/// }
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/// // Prints "0: foo"
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/// // Prints "1: bar"
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@frozen
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public struct EnumeratedSequence<Base: Sequence> {
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@usableFromInline
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internal var _base: Base
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/// Construct from a `Base` sequence.
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@inlinable
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internal init(_base: Base) {
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self._base = _base
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}
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}
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extension EnumeratedSequence: Sendable where Base: Sendable {}
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extension EnumeratedSequence {
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/// The iterator for `EnumeratedSequence`.
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///
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/// An instance of this iterator wraps a base iterator and yields
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/// successive `Int` values, starting at zero, along with the elements of the
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/// underlying base iterator. The following example enumerates the elements of
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/// an array:
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///
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/// var iterator = ["foo", "bar"].enumerated().makeIterator()
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/// iterator.next() // (0, "foo")
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/// iterator.next() // (1, "bar")
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/// iterator.next() // nil
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///
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/// To create an instance, call
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/// `enumerated().makeIterator()` on a sequence or collection.
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@frozen
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public struct Iterator {
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@usableFromInline
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internal var _base: Base.Iterator
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@usableFromInline
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internal var _count: Int
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/// Construct from a `Base` iterator.
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@inlinable
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internal init(_base: Base.Iterator) {
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self._base = _base
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self._count = 0
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}
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}
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}
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extension EnumeratedSequence.Iterator: Sendable where Base.Iterator: Sendable {}
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extension EnumeratedSequence.Iterator: IteratorProtocol, Sequence {
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/// The type of element returned by `next()`.
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public typealias Element = (offset: Int, element: Base.Element)
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/// Advances to the next element and returns it, or `nil` if no next element
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/// exists.
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///
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/// Once `nil` has been returned, all subsequent calls return `nil`.
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@inlinable
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public mutating func next() -> Element? {
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guard let b = _base.next() else { return nil }
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let result = (offset: _count, element: b)
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_count += 1
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return result
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}
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}
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extension EnumeratedSequence: Sequence {
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/// Returns an iterator over the elements of this sequence.
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@inlinable
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public __consuming func makeIterator() -> Iterator {
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return Iterator(_base: _base.makeIterator())
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}
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}
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@available(SwiftStdlib 6.1, *)
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extension EnumeratedSequence: Collection where Base: Collection {
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@available(SwiftStdlib 6.1, *)
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@frozen
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public struct Index {
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/// The position in the underlying collection.
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public let base: Base.Index
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/// The offset corresponding to this index when `base` is not the end index,
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/// `0` otherwise.
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@usableFromInline
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let _offset: Int
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@available(SwiftStdlib 6.1, *)
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@_alwaysEmitIntoClient
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init(base: Base.Index, offset: Int) {
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self.base = base
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self.offset = offset
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}
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}
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@available(SwiftStdlib 6.1, *)
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@_alwaysEmitIntoClient
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public var startIndex: Index {
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Index(base: _base.startIndex, offset: 0)
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}
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@available(SwiftStdlib 6.1, *)
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@_alwaysEmitIntoClient
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public var endIndex: Index {
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Index(base: _base.endIndex, offset: 0)
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}
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@available(SwiftStdlib 6.1, *)
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@_alwaysEmitIntoClient
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public var count: Int {
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_base.count
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}
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@available(SwiftStdlib 6.1, *)
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@_alwaysEmitIntoClient
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public var isEmpty: Bool {
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_base.isEmpty
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}
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/// Returns the offset corresponding to `index`.
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///
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/// - Complexity: O(*n*) if `index == endIndex` and `Base` does not conform to
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/// `RandomAccessCollection`, O(1) otherwise.
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@available(SwiftStdlib 6.1, *)
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@_alwaysEmitIntoClient
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func _offset(of index: Index) -> Int {
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index.base == _base.endIndex ? _base.count : index.offset
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}
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@available(SwiftStdlib 6.1, *)
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@_alwaysEmitIntoClient
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public func distance(from start: Index, to end: Index) -> Int {
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if start.base == _base.endIndex || end.base == _base.endIndex {
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return _base.distance(from: start.base, to: end.base)
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} else {
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return end.offset - start.offset
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}
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}
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@available(SwiftStdlib 6.1, *)
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@_alwaysEmitIntoClient
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public func index(after index: Index) -> Index {
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Index(base: _base.index(after: index.base), offset: index.offset + 1)
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}
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@available(SwiftStdlib 6.1, *)
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@_alwaysEmitIntoClient
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public func index(_ i: Index, offsetBy distance: Int) -> Index {
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let index = _base.index(i.base, offsetBy: distance)
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let offset = distance >= 0 ? i.offset : _offset(of: i)
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return Index(base: index, offset: offset + distance)
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}
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@available(SwiftStdlib 6.1, *)
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@_alwaysEmitIntoClient
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public func index(
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_ i: Index,
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offsetBy distance: Int,
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limitedBy limit: Index
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) -> Index? {
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guard let index = _base.index(
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i.base,
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offsetBy: distance,
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limitedBy: limit
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) else {
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return nil
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}
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let offset = distance >= 0 ? i.offset : _offset(of: i)
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return Index(base: index, offset: offset + distance)
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}
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@available(SwiftStdlib 6.1, *)
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@_alwaysEmitIntoClient
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public subscript(_ position: Int) -> Element {
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_precondition(
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_base.startIndex <= position.base && position.base < _base.endIndex,
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"Index out of bounds"
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)
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return (position.offset, _base[position.base])
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}
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}
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@available(SwiftStdlib 6.1, *)
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extension EnumeratedSequence.Index: Comparable {
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@available(SwiftStdlib 6.1, *)
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@_alwaysEmitIntoClient
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public static ==(lhs: Self, rhs: Self) -> Bool {
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lhs.base == rhs.base
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}
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@available(SwiftStdlib 6.1, *)
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@_alwaysEmitIntoClient
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public static func <(lhs: Self, rhs: Self) -> Bool {
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lhs.base < rhs.base
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}
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}
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@available(SwiftStdlib 6.1, *)
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extension EnumeratedSequence: BidirectionalCollection where Base: BidirectionalCollection {
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@available(SwiftStdlib 6.1, *)
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@_alwaysEmitIntoClient
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public func index(before index: Index) -> Index {
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Index(base: _base.index(before: index.base), offset: _offset(of: index) - 1)
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}
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}
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@available(SwiftStdlib 6.1, *)
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extension EnumeratedSequence: RandomAccessCollection where Base: RandomAccessCollection {}

‎stdlib/public/core/GroupInfo.json

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@@ -96,6 +96,7 @@
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],
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"Lazy Views": [
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"Algorithm.swift",
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"EnumeratedSequence.swift"
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"Flatten.swift",
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"FlatMap.swift",
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"Map.swift",

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