352 lines
12 KiB
C++
352 lines
12 KiB
C++
#pragma once
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/* MOUNT CONTROL COMPONENTS LIBRARY */
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/* FINITE-STATE MACHINE IMPLEMENTATION */
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#include <functional>
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#include <string_view>
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#include <typeindex>
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#include <unordered_map>
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#include <variant>
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#include "mcc_fsm_utils.h"
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namespace mcc::fsm
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{
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class MccFsmAbstractState;
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namespace traits
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{
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template <typename T>
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concept fsm_event_c =
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std::is_default_constructible_v<T> && std::is_move_constructible_v<T> && std::movable<T> && requires {
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{ T::ID } -> std::same_as<const std::string_view>; // static constant member of event identificator
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};
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template <typename T>
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concept fsm_event_state_pair_c = requires {
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[]<traits::fsm_event_c EvT, std::derived_from<MccFsmAbstractState> StT>(std::type_identity<std::pair<EvT, StT>>) {
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}(std::type_identity<T>());
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};
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template <typename T>
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concept fsm_event_state_pair_tuple_c =
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requires { []<fsm_event_state_pair_c... PTs>(std::type_identity<std::tuple<PTs...>>) {}(std::type_identity<T>()); };
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} // namespace traits
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/*
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A base FSM state class with implementation of "event -- new state" transition table
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*/
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class MccFsmAbstractState
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{
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static constexpr std::string_view ID = "MCC-FSM-STATE";
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protected:
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MccFsmAbstractState() = default;
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// helpers
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template <typename T, typename TpT>
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struct in_tuple;
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template <typename T, typename... Ts>
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struct in_tuple<T, std::tuple<Ts...>> : std::disjunction<std::is_same<T, Ts>...> {
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};
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template <typename T, typename... Ts>
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static constexpr bool in_tpl_v = in_tuple<T, Ts...>::value;
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// template <typename T, typename... PTs>
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// struct in_pair : std::disjunction<std::is_same<T, typename PTs::first_type>...> {
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// };
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template <typename T, typename... PTs>
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static constexpr bool in_pair_v = std::disjunction<std::is_same<T, typename PTs::first_type>...>::value;
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// static constexpr bool in_pair_v = in_pair<T, PTs...>::value;
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/* transition table definition */
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public:
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template <traits::fsm_event_state_pair_c... PTs>
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struct trans_table_t;
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template <traits::fsm_event_state_pair_c PT>
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struct trans_table_t<PT> {
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using events_t = std::tuple<typename PT::first_type>;
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using states_t = std::tuple<typename PT::first_second>;
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using unique_states_t = states_t;
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using evst_pairs_t = std::tuple<PT>;
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static constexpr bool unique = true;
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template <traits::fsm_event_c EvT>
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using find_state_by_event_t =
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std::conditional_t<std::same_as<EvT, typename PT::first_type>, typename PT::first_second, std::nullptr_t>;
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};
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template <traits::fsm_event_state_pair_c PT, traits::fsm_event_state_pair_c... PTs>
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struct trans_table_t<PT, PTs...> {
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private:
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using ev_t = typename PT::first_type;
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using st_t = typename PT::second_type;
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// static constexpr bool non_unique = in_pair_v<ev_t, PTs...>;
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static constexpr bool non_unique = (std::same_as<ev_t, typename PTs::second_type> || ...);
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public:
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using events_t =
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std::conditional_t<non_unique,
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typename trans_table_t<PTs...>::events_t,
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decltype(std::tuple_cat(std::declval<std::tuple<ev_t>>(),
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std::declval<typename trans_table_t<PTs...>::events_t>()))>;
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using states_t =
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std::conditional_t<non_unique,
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typename trans_table_t<PTs...>::states_t,
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decltype(std::tuple_cat(std::declval<std::tuple<st_t>>(),
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std::declval<typename trans_table_t<PTs...>::states_t>()))>;
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using unique_states_t = std::conditional_t<
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non_unique,
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typename trans_table_t<PTs...>::unique_states_t,
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std::conditional_t<(std::same_as<st_t, typename PTs::second_type> || ...),
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typename trans_table_t<PTs...>::unique_states_t,
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decltype(std::tuple_cat(
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std::declval<std::tuple<st_t>>(),
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std::declval<typename trans_table_t<PTs...>::unique_states_t>()))>>;
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using evst_pairs_t =
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std::conditional_t<non_unique,
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typename trans_table_t<PTs...>::evst_pairs_t,
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decltype(std::tuple_cat(std::declval<std::tuple<PT>>(),
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std::declval<typename trans_table_t<PTs...>::evst_pairs_t>()))>;
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private:
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template <traits::fsm_event_c EvT>
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struct find_state_by_event {
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template <size_t I = 0, typename T = void>
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struct helper {
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static constexpr size_t idx =
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std::same_as<EvT, std::tuple_element_t<I, events_t>> ? I : helper<I + 1>::idx;
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};
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// to stop unwind the recursive 'helper' template
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// in std::conditional_t trait
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template <typename T>
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struct helper<std::tuple_size_v<events_t> - 1, T> {
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static constexpr size_t idx = std::tuple_size_v<events_t> - 1;
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};
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using res_t = std::
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conditional_t<in_tpl_v<EvT, events_t>, std::tuple_element_t<helper<0>::idx, states_t>, std::nullptr_t>;
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};
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public:
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template <traits::fsm_event_c EvT>
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using find_state_by_event_t = find_state_by_event<EvT>::res_t;
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}; // end of 'trans_table_t<PT, PTs...>'
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}; // end of 'MccFsmAbstractState'
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namespace traits
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{
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template <typename T>
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concept fsm_trans_table_c = requires {
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[]<fsm_event_state_pair_c... PTs>(std::type_identity<mcc::fsm::MccFsmAbstractState::trans_table_t<PTs...>>) {
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}(std::type_identity<T>());
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};
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template <typename T>
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concept fsm_state_c =
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std::is_default_constructible_v<T> && std::is_move_constructible_v<T> && std::movable<T> &&
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std::derived_from<T, MccFsmAbstractState> && requires {
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// state class must define a type 'transition_t' which must be a full specialization of
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// MccFsmAbstractState::trans_table_t class
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[]<fsm_trans_table_c TabT>(std::type_identity<TabT>) {}(std::type_identity<typename T::transition_t>());
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};
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} // namespace traits
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template <traits::fsm_state_c InitStateT>
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class MccFiniteStateMachine
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{
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public:
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template <traits::fsm_state_c ST>
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MccFiniteStateMachine(ST initial_state) : _currentStateID(ST::ID), _currentStateIDX(typeid(ST))
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{
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// setStateFunc<ST::transition_t::evst_pairs_t>();
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initFromInitial<ST::transition_t::evst_pairs_t>(typeid(ST));
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}
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template <traits::fsm_event_c EvT>
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void dispatchEvent(EvT event)
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{
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enter_state_func_umap_t<EvT>[this][_currentStateIDX](std::move(event));
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// state_func_umap_t<EvT>[this][_currentStateIDX](std::move(event));
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}
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protected:
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template <traits::fsm_event_c EvT>
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using state_func_t = std::unordered_map<std::type_index, std::function<void(EvT)>>;
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template <traits::fsm_event_c EvT>
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inline static std::unordered_map<const MccFiniteStateMachine*, state_func_t<EvT>> state_func_umap_t{};
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template <traits::fsm_event_c EvT>
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inline static std::unordered_map<const MccFiniteStateMachine*, state_func_t<EvT>> enter_state_func_umap_t{};
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template <traits::fsm_event_c EvT>
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inline static std::unordered_map<const MccFiniteStateMachine*, state_func_t<EvT>> exit_state_func_umap_t{};
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std::string_view _currentStateID;
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std::type_index _currentStateIDX;
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std::function<void()> _exitCurrentStateFunc;
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template <traits::fsm_event_state_pair_c PT, traits::fsm_event_state_pair_c... PTs>
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consteval static void initFromInitial(std::type_index state_idx)
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{
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initFromInitial<PT>(state_idx);
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if constexpr (sizeof...(PTs)) {
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initFromInitial<PTs...>(state_idx);
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}
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}
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template <traits::fsm_event_state_pair_c PT>
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consteval static void initFromInitial(std::type_index state_idx)
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{
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using ev_t = typename PT::first_type;
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using st_t = typename PT::second_type;
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enter_state_func_umap_t<ev_t>[][state_idx] = [](ev_t event) {
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st_t state;
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initFromInitial<st_t::transition_t::evst_pairs_t>(st_t::ID);
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if constexpr (requires(st_t inst) {
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{ inst.enter(std::declval<ev_t>()) };
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}) {
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state.enter(std::move(event));
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} else {
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state.enter();
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}
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};
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}
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// template <traits::fsm_event_state_pair_c PT, traits::fsm_event_state_pair_c... PTs>
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// void setStateFunc()
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// {
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// setStateFunc<PT>();
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// if constexpr (sizeof...(PTs)) {
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// setStateFunc<PTs...>();
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// }
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// }
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// template <traits::fsm_event_state_pair_c PT>
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// void setStateFunc()
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// {
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// using ev_t = typename PT::first_type;
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// using st_t = typename PT::second_type;
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// state_func_umap_t<ev_t>[this][_currentStateIDX] = [](ev_t event) {
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// st_t state;
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// if constexpr (requires(st_t inst) {
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// { inst.enter(std::declval<ev_t>()) };
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// }) {
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// state.enter(std::move(event));
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// } else {
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// state.enter();
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// }
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// };
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// }
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// template<>
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// merge N std::tuple types with filtering dublicates
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// (NOTE: the first std::tuple type must contain unique types!!!)
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template <typename... TplTs>
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struct merge_tuples_t;
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template <>
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struct merge_tuples_t<> {
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using res_t = std::tuple<>;
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};
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template <typename TplT>
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struct merge_tuples_t<TplT> {
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using res_t = TplT;
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};
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template <typename TplT1, typename TplT2>
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struct merge_tuples_t<TplT1, TplT2> {
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using res_t = TplT1;
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};
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template <typename... T1, typename T2, typename... T2s>
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struct merge_tuples_t<std::tuple<T1...>, std::tuple<T2, T2s...>>
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: std::conditional_t<(std::same_as<T1, T2> || ...),
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merge_tuples_t<std::tuple<T1...>, std::tuple<T2s...>>,
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merge_tuples_t<std::tuple<T1..., T2>, std::tuple<T2s...>>> {
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};
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template <typename TplT1, typename TplT2, typename TplT3, typename... TplTs>
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struct merge_tuples_t<TplT1, TplT2, TplT3, TplTs...>
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: merge_tuples_t<typename merge_tuples_t<TplT1, TplT2>::res_t, TplT3, TplTs...> {
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};
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template <typename... TplTs>
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using merge_tuples_res_t = typename merge_tuples_t<TplTs...>::res_t;
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template <typename TplT>
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struct variant_maker_t;
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template <typename... Ts>
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struct variant_maker_t<std::tuple<Ts...>> {
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// using variant_t = std::variant<Ts*...>;
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using variant_t = std::variant<std::reference_wrapper<Ts>...>;
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};
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template <typename... TplTs>
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struct collect_states_t;
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// template <typename TplT>
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// struct collect_states_t<TplT> {
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// using states_t = TplT;
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// };
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template <traits::fsm_state_c... StTs, typename... TplTs>
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struct collect_states_t<std::tuple<StTs...>, TplTs...> {
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using states_t =
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merge_tuples_res_t<std::tuple<StTs...>,
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typename collect_states_t<typename StTs::transition_t::unique_states_t...>::states_t,
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TplTs...>;
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};
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using states_t = typename collect_states_t<InitStateT>::states_t;
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states_t _states;
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typename variant_maker_t<states_t>::variant_t _currentStateVariant;
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};
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} // namespace mcc::fsm
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