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6821aca587
Now we support casting and bridging to/from [Any], not just [AnyObject] Note that the typechecker still doesn't allow all the casts we'd like; see the FIXMEs in test/1_stdlib/ArrayBridge.swift.gyb.
65 lines
2.4 KiB
Swift
65 lines
2.4 KiB
Swift
//===--- ArrayCast.swift - Casts and conversions for Array ----------------===//
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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) 2014 - 2016 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 http://swift.org/LICENSE.txt for license information
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// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// Because NSArray is effectively an [AnyObject], casting [T] -> [U]
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// is an integral part of the bridging process and these two issues
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// are handled together.
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//
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//===----------------------------------------------------------------------===//
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/// Implements `source as! [TargetElement]`.
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///
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/// - Note: When SourceElement and TargetElement are both bridged verbatim, type
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/// checking is deferred until elements are actually accessed.
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public func _arrayForceCast<SourceElement, TargetElement>(
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_ source: Array<SourceElement>
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) -> Array<TargetElement> {
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#if _runtime(_ObjC)
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if _isClassOrObjCExistential(SourceElement.self)
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&& _isClassOrObjCExistential(TargetElement.self) {
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let src = source._buffer
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if let native = src.requestNativeBuffer() {
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if native.storesOnlyElementsOfType(TargetElement.self) {
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// A native buffer that is known to store only elements of the
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// TargetElement can be used directly
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return Array(_buffer: src.cast(toBufferOf: TargetElement.self))
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}
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// Other native buffers must use deferred element type checking
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return Array(_buffer:
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src.downcast(toBufferWithDeferredTypeCheckOf: TargetElement.self))
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}
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return Array(_immutableCocoaArray: source._buffer._asCocoaArray())
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}
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#endif
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return _arrayConditionalCast(source)!
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}
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internal struct _UnwrappingFailed : Error {}
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extension Optional {
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internal func unwrappedOrError() throws -> Wrapped {
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if let x = self { return x }
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throw _UnwrappingFailed()
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}
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}
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/// Implements `source as? [TargetElement]`: convert each element of
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/// `source` to a `TargetElement` and return the resulting array, or
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/// return `nil` if any element fails to convert.
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///
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/// - Complexity: O(n), because each element must be checked.
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public func _arrayConditionalCast<SourceElement, TargetElement>(
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_ source: [SourceElement]
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) -> [TargetElement]? {
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return try? source.map { try ($0 as? TargetElement).unwrappedOrError() }
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}
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