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// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_USER_MANAGER_SCOPED_USER_MANAGER_H_
#define COMPONENTS_USER_MANAGER_SCOPED_USER_MANAGER_H_
#include <memory>
#include <utility>
#include "base/memory/raw_ptr.h"
#include "components/user_manager/user_manager_export.h"
namespace user_manager {
class UserManager;
namespace internal {
// Implementation details of ScopedUserManager.
class USER_MANAGER_EXPORT ScopedUserManagerImpl {
public:
ScopedUserManagerImpl();
ScopedUserManagerImpl(const ScopedUserManagerImpl&) = delete;
ScopedUserManagerImpl& operator=(const ScopedUserManagerImpl&) = delete;
~ScopedUserManagerImpl();
void Reset(std::unique_ptr<UserManager> user_manager);
UserManager* Get() const { return user_manager_.get(); }
private:
// Owns the passed UserManager.
std::unique_ptr<UserManager> user_manager_;
// Keeps the original UserManager to restore on destruction.
raw_ptr<UserManager> previous_user_manager_ = nullptr;
};
} // namespace internal
// Helper class for unit tests. Initializes the UserManager singleton to the
// given UserManager and tears it down again on destruction. If the singleton
// had already been initialized, its previous value is restored after tearing
// down.
//
// Example use case.
// class FooTest : public testing::Test {
// public:
// void SetUp() override {
// fake_user_manager_.Reset(std::make_unique<FakeUserManager>());
// fake_user_manager_->AddUser(...);
// ...
// }
// private:
// TypedScopedUserManager<FakeUserManager> fake_user_manager_;
// };
//
template <typename T>
class USER_MANAGER_EXPORT TypedScopedUserManager {
public:
static_assert(std::is_base_of_v<UserManager, T>,
"Template parameter of ScopedUserManager must be a subclass "
"of UserManager.");
// Do nothing on initialization. Later, Reset() can be called to overwrite
// global UserManager.
TypedScopedUserManager() = default;
// Replaces global UserManager by the given one. On destruction,
// original one will be restored.
explicit TypedScopedUserManager(std::unique_ptr<T> user_manager) {
impl_.Reset(std::move(user_manager));
}
// Note: we may want to consider to make this movable, but at this moment
// there're no use cases found.
TypedScopedUserManager(const TypedScopedUserManager&) = delete;
TypedScopedUserManager& operator=(const TypedScopedUserManager&) = delete;
~TypedScopedUserManager() { impl_.Reset(nullptr); }
// Resets the global UserManager by the given one.
// If the global UserManager is overwritten by another ScopedUserManager,
// this will fail.
void Reset(std::unique_ptr<T> user_manager = nullptr) {
impl_.Reset(std::move(user_manager));
}
// Returns the UserManager in specified type.
T* Get() const { return static_cast<T*>(impl_.Get()); }
// Operator overloads for better syntax supports:
T& operator*() const noexcept(noexcept(*std::declval<T*>)) { return *Get(); }
T* operator->() const noexcept { return Get(); }
private:
internal::ScopedUserManagerImpl impl_;
};
using ScopedUserManager = TypedScopedUserManager<UserManager>;
} // namespace user_manager
#endif // COMPONENTS_USER_MANAGER_SCOPED_USER_MANAGER_H_
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