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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef GPU_WEBGPU_CALLBACK_H_
#define GPU_WEBGPU_CALLBACK_H_
#include <memory>
#include "base/functional/callback.h"
namespace gpu::webgpu {
// WGPUCallback<Callback> is a heap-allocated version of
// base::OnceCallback or base::RepeatingCallback.
// It is allocated on the heap so that it can be reinterpret_cast to/from
// void* and passed to WGPU C callbacks.
//
// Example:
// WGPUOnceCallback<F>* callback =
// BindWGPUOnceCallback(func, arg1);
//
// // |someWGPUFunction| expects callback function with arguments:
// // Args... args, void* userdata.
// // When it is called, it will forward to func(arg1, args...).
// GetProcs().someWGPUFunction(
// callback->UnboundCallback(), callback->AsUserdata());
template <typename Callback>
class WGPUCallbackBase;
template <typename Callback>
class WGPUOnceCallback;
template <typename Callback>
class WGPURepeatingCallback;
template <template <typename> class BaseCallbackTemplate,
typename R,
typename... Args>
class WGPUCallbackBase<BaseCallbackTemplate<R(Args...)>> {
using BaseCallback = BaseCallbackTemplate<R(Args...)>;
static constexpr bool is_once_callback =
std::is_same<BaseCallback, base::OnceCallback<R(Args...)>>::value;
static constexpr bool is_repeating_callback =
std::is_same<BaseCallback, base::RepeatingCallback<R(Args...)>>::value;
static_assert(
is_once_callback || is_repeating_callback,
"Callback must be base::OnceCallback or base::RepeatingCallback");
public:
explicit WGPUCallbackBase(BaseCallback callback)
: callback_(std::move(callback)) {}
void* AsUserdata() { return static_cast<void*>(this); }
protected:
using UnboundCallbackFunction = R (*)(Args..., void*);
static WGPUCallbackBase* FromUserdata(void* userdata) {
return static_cast<WGPUCallbackBase*>(userdata);
}
R Run(Args... args) && {
static_assert(
is_once_callback,
"Run on a moved receiver must only be called on a once callback.");
return std::move(callback_).Run(std::forward<Args>(args)...);
}
R Run(Args... args) const& {
static_assert(is_repeating_callback,
"Run on a unmoved receiver must only be called on a "
"repeating callback.");
return callback_.Run(std::forward<Args>(args)...);
}
private:
BaseCallback callback_;
};
template <typename R, typename... Args>
class WGPUOnceCallback<R(Args...)>
: public WGPUCallbackBase<base::OnceCallback<R(Args...)>> {
using BaseCallback = base::OnceCallback<R(Args...)>;
public:
using WGPUCallbackBase<BaseCallback>::WGPUCallbackBase;
typename WGPUCallbackBase<BaseCallback>::UnboundCallbackFunction
UnboundCallback() {
return CallUnboundOnceCallback;
}
private:
static R CallUnboundOnceCallback(Args... args, void* handle) {
// After this non-repeating callback is run, it should delete itself.
auto callback =
std::unique_ptr<WGPUOnceCallback>(static_cast<WGPUOnceCallback*>(
WGPUCallbackBase<BaseCallback>::FromUserdata(handle)));
return std::move(*callback).Run(std::forward<Args>(args)...);
}
};
template <typename R, typename... Args>
class WGPURepeatingCallback<R(Args...)>
: public WGPUCallbackBase<base::RepeatingCallback<R(Args...)>> {
using BaseCallback = base::RepeatingCallback<R(Args...)>;
public:
using WGPUCallbackBase<BaseCallback>::WGPUCallbackBase;
typename WGPUCallbackBase<BaseCallback>::UnboundCallbackFunction
UnboundCallback() {
return CallUnboundRepeatingCallback;
}
private:
static R CallUnboundRepeatingCallback(Args... args, void* handle) {
return static_cast<WGPURepeatingCallback*>(
WGPUCallbackBase<BaseCallback>::FromUserdata(handle))
->Run(std::forward<Args>(args)...);
}
};
template <typename FunctionType, typename... BoundParameters>
auto BindWGPUOnceCallback(FunctionType&& function,
BoundParameters&&... bound_parameters) {
static constexpr bool is_method =
base::internal::MakeFunctorTraits<FunctionType>::is_method;
static constexpr bool is_weak_method =
base::internal::IsWeakMethod<is_method, BoundParameters...>();
static_assert(!is_weak_method,
"BindWGPUOnceCallback cannot be used with weak methods");
auto cb = base::BindOnce(std::forward<FunctionType>(function),
std::forward<BoundParameters>(bound_parameters)...);
return new WGPUOnceCallback<typename decltype(cb)::RunType>(std::move(cb));
}
template <typename FunctionType, typename... BoundParameters>
auto BindWGPURepeatingCallback(FunctionType&& function,
BoundParameters&&... bound_parameters) {
auto cb =
base::BindRepeating(std::forward<FunctionType>(function),
std::forward<BoundParameters>(bound_parameters)...);
return std::make_unique<
WGPURepeatingCallback<typename decltype(cb)::RunType>>(std::move(cb));
}
} // namespace gpu::webgpu
#endif // GPU_WEBGPU_CALLBACK_H_
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