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# Motivation For AsyncStream we created a custom internal Deque implementation to use for the buffering. This implementation was relatively bare-bones compared to the one in swift-collections. Furthermore, it lacked some methods that we need to implement the new `AsyncStream` APIs that support producer backpressure. # Modification This PR copies over the Deque implementation of swift-collections and makes it internal and non-inlinable. # Result We now have a fully functional Deque.
60 lines
1.8 KiB
Swift
60 lines
1.8 KiB
Swift
//===----------------------------------------------------------------------===//
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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) 2021 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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//
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//===----------------------------------------------------------------------===//
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/// This file is copied from swift-collections and should not be modified here.
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/// Rather all changes should be made to swift-collections and copied back.
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import Swift
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extension Collection {
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internal func _rebased<Element>() -> UnsafeBufferPointer<Element>
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where Self == UnsafeBufferPointer<Element>.SubSequence {
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.init(rebasing: self)
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}
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}
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extension Collection {
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internal func _rebased<Element>() -> UnsafeMutableBufferPointer<Element>
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where Self == UnsafeMutableBufferPointer<Element>.SubSequence {
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.init(rebasing: self)
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}
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}
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extension UnsafeMutableBufferPointer {
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internal func _initialize(from source: UnsafeBufferPointer<Element>) {
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assert(source.count == count)
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guard source.count > 0 else { return }
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baseAddress!.initialize(from: source.baseAddress!, count: source.count)
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}
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internal func _initialize<C: Collection>(
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from elements: C
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) where C.Element == Element {
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assert(elements.count == count)
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var (it, copied) = elements._copyContents(initializing: self)
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precondition(copied == count)
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precondition(it.next() == nil)
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}
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internal func _deinitializeAll() {
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guard count > 0 else { return }
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baseAddress!.deinitialize(count: count)
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}
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internal func _assign<C: Collection>(
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from replacement: C
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) where C.Element == Element {
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guard self.count > 0 else { return }
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self[0 ..< count]._rebased()._deinitializeAll()
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_initialize(from: replacement)
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}
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}
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