55 lines
1.3 KiB
C++
55 lines
1.3 KiB
C++
#pragma once
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#include <cassert>
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#include <td/misc/Signal.h>
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namespace td {
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template <typename TDerived, typename TReturn, typename... TArgs>
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class StateMachine {
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public:
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class State {
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public:
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State(TDerived& a_StateMachine) : m_StateMachine(a_StateMachine) {}
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virtual ~State() {}
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virtual TReturn Update(TArgs... args) = 0;
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template <typename T, typename... Args>
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T* ChangeState(Args... args) {
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return m_StateMachine.template ChangeState<T>(std::forward<Args>(args)...);
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}
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protected:
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TDerived& m_StateMachine;
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};
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utils::Signal<State&> OnStateChange;
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StateMachine() {}
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StateMachine(StateMachine&&) = default;
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virtual ~StateMachine() {}
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virtual TReturn Update(TArgs... args) {
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assert(m_State && "You must change state at least once before updating !");
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return m_State->Update(std::forward<TArgs>(args)...);
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}
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template <typename T, typename... Args>
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T* ChangeState(Args... args) {
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auto* currentState = m_State.get();
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auto newState = std::make_unique<T>(static_cast<TDerived&>(*this), std::forward<Args>(args)...);
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// This allows chaining
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if (m_State.get() == currentState)
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m_State = std::move(newState);
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OnStateChange(*m_State);
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return static_cast<T*>(m_State.get());
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}
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private:
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std::unique_ptr<State> m_State;
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};
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} // namespace td
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