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// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CHROME_BROWSER_WEB_APPLICATIONS_CALLBACK_UTILS_H_
#define CHROME_BROWSER_WEB_APPLICATIONS_CALLBACK_UTILS_H_
#include "base/functional/callback.h"
#include "base/memory/weak_ptr.h"
namespace web_app {
// RunChainedCallbacks() runs multiple callbacks chained together by
// successively binding the final callback as parameter to the one before it
// until the entire sequence has been bound together.
//
// Example usage:
//
// class CounterStorage {
// public:
// void AddToCounter(size_t value, base::OnceClosure callback) {
// auto weak_ptr = weak_ptr_factory_.GetWeakPtr();
// RunChainedCallbacks(
// base::BindOnce(&CounterStorage::AcquireFileLock, weak_ptr),
// base::BindOnce(&CounterStorage::StashFileLock, weak_ptr),
// base::BindOnce(&CounterStorage::ReadCounter, weak_ptr),
// base::BindOnce(&CounterStorage::Add, weak_ptr, value),
// base::BindOnce(&CounterStorage::WriteCounter, weak_ptr),
// base::BindOnce(&CounterStorage::ReleaseFileLock, weak_ptr),
// std::move(callback));
// }
//
// private:
// void AcquireFileLock(
// base::OnceCallback<void(FileLock)> next_step_callback);
// void StashFileLock(base::OnceClosure next_step_callback, FileLock lock);
// void ReadCounter(base::OnceCallback<void(size_t)> next_step_callback);
// void Add(size_t value,
// base::OnceCallback<void(size_t)> next_step_callback,
// size_t count);
// void WriteCounter(base::OnceClosure next_step_callback, size_t count);
// void ReleaseFileLock(base::OnceClosure next_step_callback);
//
// std::optional<FileLock> lock_;
// base::WeakPtrFactory<CounterStorage> weak_ptr_factory_{this};
// };
//
// The alternate way to write AddLog() without RunChainedCallbacks() would be:
// base::BindOnce(
// &Logger::AcquireFileLock,
// weak_ptr,
// base::BindOnce(
// &Logger::StashFileLock,
// weak_ptr,
// base::BindOnce(
// &Logger::ReadCounter,
// weak_ptr,
// base::BindOnce(
// &Logger::Add,
// weak_ptr,
// value,
// base::BindOnce(&Logger::WriteCounter,
// weak_ptr,
// base::BindOnce(&Logger::ReleaseFileLock,
// weak_ptr,
// std::move(callback)))))));
//
// RunChainedCallbacks() allows writing single action async methods that don't
// need to know about the high level procedure while avoiding messy indented
// nesting of multiple base::BindOnce() calls.
template <typename Callback>
Callback ChainCallbacks(Callback&& callback) {
return std::forward<Callback>(callback);
}
template <typename FirstCallback, typename... NextCallbacks>
decltype(auto) ChainCallbacks(FirstCallback&& first_callback,
NextCallbacks&&... next_callbacks) {
return base::BindOnce(std::forward<FirstCallback>(first_callback),
ChainCallbacks<NextCallbacks...>(
std::forward<NextCallbacks>(next_callbacks)...));
}
template <typename... Callbacks>
decltype(auto) RunChainedCallbacks(Callbacks&&... callbacks) {
return ChainCallbacks(std::forward<Callbacks>(callbacks)...).Run();
}
template <typename T, typename... Funcs>
decltype(auto) RunChainedWeakCallbacks(base::WeakPtr<T> weak_ptr,
Funcs... funcs) {
return RunChainedCallbacks(base::BindOnce(funcs, weak_ptr)...);
}
} // namespace web_app
#endif // CHROME_BROWSER_WEB_APPLICATIONS_CALLBACK_UTILS_H_
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