c++ - Boost msm 子子状态机

Question

我在使用 boost::msm 实现子子状态机时遇到了一些麻烦。我试图在这里最小化我的代码...

测试.cpp:

struct SM_ : StateMachineA<SM_> {};
// Pick a back-end
typedef boost::msm::back::state_machine<SM_> SM;
int main()
{
    std::cout << "Starting State Machine" << std::endl;
    SM sm1;
    //  sm1.start();
    return 0;
}

StateMachineA在StateMachineA.h中定义

namespace msmf = boost::msm::front;
namespace mpl = boost::mpl;
template<typename Derived>
struct StateMachineA: protected msmf::state_machine_def < Derived, msmf::default_base_state >
        {
        public:

            //// Entry point to state machine. 

            //// Set initial state
            typedef mpl::vector<initState, allOk> initial_state;

            //// Exit Point
            struct Exit :msmf::terminate_state<> {};

            // ----- Sub State machine
            struct SSM_ : StateMachineB<SSM_> {};

            // Pick a back-end
            typedef boost::msm::back::state_machine<SSM_> stateMachineB;


            //// Transition table
            struct transition_table : mpl::vector<
                msmf::Row < initState, go, stateMachineB, msmf::none, msmf::none >,
                msmf::Row < allOk, fatalThrown, Exit, msmf::none, msmf::none >,
                msmf::Row < error, fatalThrown, Exit, msmf::none, msmf::none >
            > {};




        protected:


            template <class FSM, class Event>
            void no_transition(Event const&, FSM&, int)
            {
                std::cout << "ERROR: Unallowed transition detected" << std::endl;
            }
        };

StateMachineB 包含一个 StateMachineC，使用完全相同的代码(用 C 替换 B...)。

将 StateMachineC 作为 StateMachineA 的子机(省略 StateMachineB)工作正常。对于不包括 C 的 A -> B 也同样有效。重新排序状态机 (A -> C -> B) 会产生相同的错误。总结一下:两个状态机的每个组合都在工作，三个状态机的每个组合都在失败。当我的主函数中有 SM sm1; 时会发生错误。 -> 在解析模板时？没有那一行，一切都可以正常编译。

错误日志很长(长到足以导致 visual studio 在悬停时崩溃...)。第一个错误是:

D:\boost_1_59_0\boost/mpl/aux_/push_front_impl.hpp(45) : error C2664: 'int    boost::mpl::assertion_failed<false>(boost::mpl::assert<false>::type)' : cannot convert argument 1 from 'boost::mpl::failed ************(__thiscall boost::mpl::push_front_impl<boost::mpl::aux::vector_tag<20>>::apply<Sequence,T>::REQUESTED_PUSH_FRONT_SPECIALIZATION_FOR_SEQUENCE_DOES_NOT_EXIST::* ***********)(Sequence)' to 'boost::mpl::assert<false>::type'

与... 以及大约 200 条“with”行。之后，出现许多类型的错误:

D:\boost_1_59_0\boost/mpl/aux_/insert_impl.hpp(60) : error C3203: 'type' : unspecialized class template can't be used as a template argument for template parameter 'State', expected a real type
D:\boost_1_59_0\boost/mpl/insert.hpp(32) : error C2903: 'apply' : symbol is neither a class template nor a function template
    D:\boost_1_59_0\boost/mpl/aux_/has_type.hpp(20) : see reference to class template instantiation 'boost::mpl::insert<U1,U2,U3>' being compiled

关注。

有什么想法吗？

谢谢!

Answer 1

我无法重现您的情况，但我可以向您展示如何实现 SubSub 状态机。这是我写的文档。它描述了子状态机。 http://redboltz.wikidot.com/sub-machine-state

要实现 SubSub 状态机，只需应用两次子机实现即可。

这是包含 SubSub 状态机的代码:

#include <iostream>
#include <boost/msm/back/state_machine.hpp>

#include <boost/msm/front/state_machine_def.hpp>
#include <boost/msm/front/functor_row.hpp>
#include <boost/static_assert.hpp>

namespace msm = boost::msm;
namespace msmf = boost::msm::front;
namespace mpl = boost::mpl;

// StateMachine [Osm]
//
// (initial)
//    |
//    V
// State1:StateSub --Event1--> State2
//
//
// StateMachine [StateSub]
//
// (initial)
//    |
//    V
// SubState1 --Event2--> SubState2:StateSubSub
//    A                          |
//    +--------Event3------------+
//
//
// StateMachine [StateSubSub]
//
// (initial)
//    |
//    V
// SubSubState1---Event4--> SubSubState2
//    A                          |
//    +-----------Event5---------+



// ----- Events
struct Event1 {};
struct Event2 {};
struct Event3 {};
struct Event4 {};
struct Event5 {};

// ----- State machine
struct StateSubSub_:msmf::state_machine_def<StateSubSub_>
{
    struct SubSubState1:msmf::state<> {
        template <class Event,class Fsm>
        void on_entry(Event const&, Fsm&) const {
            BOOST_STATIC_ASSERT((boost::is_convertible<Fsm, StateSubSub_>::value));
            std::cout << "SubSubState1::on_entry()" << std::endl;
        }
        template <class Event,class Fsm>
        void on_exit(Event const&, Fsm&) const {
            BOOST_STATIC_ASSERT((boost::is_convertible<Fsm, StateSubSub_>::value));
            std::cout << "SubSubState1::on_exit()" << std::endl;
        }
    };
    struct SubSubState2:msmf::state<> {
        template <class Event,class Fsm>
        void on_entry(Event const&, Fsm&) const {
            BOOST_STATIC_ASSERT((boost::is_convertible<Fsm, StateSubSub_>::value));
            std::cout << "SubSubState2::on_entry()" << std::endl;
        }
        template <class Event,class Fsm>
        void on_exit(Event const&, Fsm&) const {
            BOOST_STATIC_ASSERT((boost::is_convertible<Fsm, StateSubSub_>::value));
            std::cout << "SubSubState2::on_exit()" << std::endl;
        }
    };

    // Set initial state
    typedef mpl::vector<SubSubState1> initial_state;
    // Transition table
    struct transition_table:mpl::vector<
        //          Start      Event   Next       Action      Guard
        msmf::Row < SubSubState1, Event4, SubSubState2, msmf::none, msmf::none >,
        msmf::Row < SubSubState2, Event5, SubSubState1, msmf::none, msmf::none >
    > {};
};
typedef msm::back::state_machine<StateSubSub_> StateSubSub;


// ----- State machine
struct StateSub_:msmf::state_machine_def<StateSub_>
{
    struct SubState1:msmf::state<> {
        template <class Event,class Fsm>
        void on_entry(Event const&, Fsm&) const {
            BOOST_STATIC_ASSERT((boost::is_convertible<Fsm, StateSub_>::value));
            std::cout << "SubState1::on_entry()" << std::endl;
        }
        template <class Event,class Fsm>
        void on_exit(Event const&, Fsm&) const {
            BOOST_STATIC_ASSERT((boost::is_convertible<Fsm, StateSub_>::value));
            std::cout << "SubState1::on_exit()" << std::endl;
        }
    };
    struct SubState2_:msmf::state_machine_def<SubState2_>
    {
        template <class Event,class Fsm>
        void on_entry(Event const&, Fsm&) const {
            BOOST_STATIC_ASSERT((boost::is_convertible<Fsm, StateSub_>::value));
            std::cout << "SubState2::on_entry()" << std::endl;
        }
        template <class Event,class Fsm>
        void on_exit(Event const&, Fsm&) const {
            BOOST_STATIC_ASSERT((boost::is_convertible<Fsm, StateSub_>::value));
            std::cout << "SubState2::on_exit()" << std::endl;
        }
        struct Impl_:StateSubSub {};
        typedef Impl_ initial_state;
    };
    // Pick a back-end
    typedef msm::back::state_machine<SubState2_> SubState2;

    // Set initial state
    typedef mpl::vector<SubState1> initial_state;
    // Transition table
    struct transition_table:mpl::vector<
        //          Start      Event   Next       Action      Guard
        msmf::Row < SubState1, Event2, SubState2, msmf::none, msmf::none >,
        msmf::Row < SubState2, Event3, SubState1, msmf::none, msmf::none >
    > {};
};
typedef msm::back::state_machine<StateSub_> StateSub;

struct OuterSm_:msmf::state_machine_def<OuterSm_>
{
    struct State1_:msmf::state_machine_def<State1_>
    {
        template <class Event,class Fsm>
        void on_entry(Event const&, Fsm&) const {
            BOOST_STATIC_ASSERT((boost::is_convertible<Fsm, OuterSm_>::value));
            std::cout << "State1::on_entry()" << std::endl;
        }
        template <class Event,class Fsm>
        void on_exit(Event const&, Fsm&) const {
            BOOST_STATIC_ASSERT((boost::is_convertible<Fsm, OuterSm_>::value));
            std::cout << "State1::on_exit()" << std::endl;
        }
        struct Impl_:StateSub {};
        typedef Impl_ initial_state;
    };
    // Pick a back-end
    typedef msm::back::state_machine<State1_> State1;
    struct State2:msmf::state<>
    {
        template <class Event,class Fsm>
        void on_entry(Event const&, Fsm&) const {
            BOOST_STATIC_ASSERT((boost::is_convertible<Fsm, OuterSm_>::value));
            std::cout << "State2::on_entry()" << std::endl;
        }
        template <class Event,class Fsm>
        void on_exit(Event const&, Fsm&) const {
            BOOST_STATIC_ASSERT((boost::is_convertible<Fsm, OuterSm_>::value));
            std::cout << "State2::on_exit()" << std::endl;
        }
    };
    // Set initial state
    typedef State1 initial_state;
    // Transition table
    struct transition_table:mpl::vector<
        //          Start   Event   Next    Action      Guard
        msmf::Row < State1, Event1, State2, msmf::none, msmf::none >
    > {};
};

// Pick a back-end
typedef msm::back::state_machine<OuterSm_> Osm;

void test()
{
    Osm osm;
    osm.start();

    std::cout << "> Send Event2()" << std::endl;
    osm.process_event(Event2());
    std::cout << "> Send Event4()" << std::endl;
    osm.process_event(Event4());
    std::cout << "> Send Event5()" << std::endl;
    osm.process_event(Event5());
    std::cout << "> Send Event3()" << std::endl;
    osm.process_event(Event3());
    std::cout << "> Send Event1()" << std::endl;
    osm.process_event(Event1());
}

int main()
{
    test();
}

您可以在在线编译器Wandbox上编译、运行和修改它。

https://wandbox.org/permlink/tBCSQDNhkBQkXxh0