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111 lines
3.2 KiB
Swift
111 lines
3.2 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) 2014 - 2015 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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/// An instance of this struct keeps the references registered with it
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/// at +1 reference count until the call to `release()`.
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///
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/// It is absolutely necessary to call `release()`. Forgetting to call
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/// `release()` will not cause a memory leak. Instead, the managed objects will be
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/// released earlier than expected.
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///
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/// This class can be used to extend lifetime of objects to pass UnsafePointers
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/// to them to C APIs.
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@internal class LifetimeManager {
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var _managedRefs : [Builtin.NativeObject]
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var _releaseCalled : Bool
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init() {
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_managedRefs = []
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_releaseCalled = false
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}
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deinit {
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if !_releaseCalled {
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_fatalError("release() should have been called")
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}
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}
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func put(objPtr: Builtin.NativeObject) {
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_managedRefs.append(objPtr)
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}
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// FIXME: Need class constraints for this to work properly.
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// func put<T>(obj: T) {
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// put(Builtin.castToNativeObject(obj))
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// }
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/// Call this function to end the forced lifetime extension.
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func release() {
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_fixLifetime(_managedRefs._owner)
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_releaseCalled = true
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}
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}
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/// Evaluate `f()` and return its result, ensuring that `x` is not
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/// destroyed before f returns.
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@public func withExtendedLifetime<T, Result>(
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x: T, f: ()->Result
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) -> Result {
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let result = f()
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_fixLifetime(x)
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return result
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}
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/// Evaluate `f(x)` and return its result, ensuring that `x` is not
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/// destroyed before f returns.
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@public func withExtendedLifetime<T, Result>(
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x: T, f: (T)->Result
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) -> Result {
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let result = f(x)
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_fixLifetime(x)
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return result
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}
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extension String {
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/// Invoke `f` on the contents of this string, represented as
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/// a nul-terminated array of char, ensuring that the array's
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/// lifetime extends through the execution of `f`.
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@public func withCString<Result>(
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f: (ConstUnsafePointer<Int8>)->Result
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) -> Result {
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return self.nulTerminatedUTF8.withUnsafePointerToElements {
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f(ConstUnsafePointer($0))
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}
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}
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/// Invoke `f` on the contents of this string, represented as
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/// a nul-terminated array of char, ensuring that the array's
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/// lifetime extends through the execution of `f`.
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@public func withCString<Result>(
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f: (UnsafePointer<CChar>)->Result
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) -> Result {
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// FIXME: This interface isn't const-correct; only the UnsafePointer variant
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// above should be available.
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return self.nulTerminatedUTF8.withUnsafePointerToElements {
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f(UnsafePointer($0))
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}
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}
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}
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// This function should be opaque to the optimizer.
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// BLOCKED: <rdar://problem/16464507> This function will be unnecessary when
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// fix_lifetime is honored by the ARC optimizer.
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@asmname("swift_keepAlive") @internal
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func _swift_keepAlive<T>(inout _: T)
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@transparent @public
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func _fixLifetime<T>(var x: T) {
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_swift_keepAlive(&x)
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}
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