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//===--- AsyncLet.h - ABI structures for async let -00-----------*- C++ -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2020 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
//
//===----------------------------------------------------------------------===//
//
// Swift ABI describing task groups.
//
//===----------------------------------------------------------------------===//
#ifndef SWIFT_ABI_TASK_ASYNC_LET_BACKDEPLOY56_H
#define SWIFT_ABI_TASK_ASYNC_LET_BACKDEPLOY56_H
#include "Task.h"
#include "swift/ABI/HeapObject.h"
#include "swift/Runtime/Config.h"
#include "swift/Basic/RelativePointer.h"
#include "swift/Basic/STLExtras.h"
namespace swift {
/// Represents an in-flight `async let`, i.e. the Task that is computing the
/// result of the async let, along with the awaited status and other metadata.
class alignas(Alignment_AsyncLet) AsyncLet {
public:
// These constructors do not initialize the AsyncLet instance, and the
// destructor does not destroy the AsyncLet instance; you must call
// swift_asyncLet_{start,end} yourself.
constexpr AsyncLet()
: PrivateData{} {}
void *PrivateData[NumWords_AsyncLet];
// TODO: we could offer a "was awaited on" check here
/// Returns the child task that is associated with this async let.
/// The tasks completion is used to fulfil the value represented by this async let.
AsyncTask *getTask() const;
// The compiler preallocates a large fixed space for the `async let`, with the
// intent that most of it be used for the child task context. The next two
// methods return the address and size of that space.
/// Return a pointer to the unused space within the async let block.
void *getPreallocatedSpace();
/// Return the size of the unused space within the async let block.
static size_t getSizeOfPreallocatedSpace();
/// Was the task allocated out of the parent's allocator?
bool didAllocateFromParentTask();
/// Flag that the task was allocated from the parent's allocator.
void setDidAllocateFromParentTask(bool value = true);
};
} // end namespace swift
#endif // SWIFT_ABI_TASK_ASYNC_LET_BACKDEPLOY56_H
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