我打算将boost.msm与包含正交区域的复合概念一起使用。我想在退出时同步所有正交区域。换句话说：当且仅当所有区域都达到其最后一个状态时，我的组合之后的状态才会被激活。
UML 2.4 “上层结构”提出了连接伪状态（即第 15.3.8 章）。在 boost 中，有一个fork，但我找不到它的对应连接的任何实现。
boost.msm 中没有加入伪状态吗？我将如何使用 boost.msm 应用加入伪状态的概念？
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您可以使用一个计数器，每次进入连接状态时它都会增加。当此计数器等于正交区域的数量时，将激活加入状态之后的状态。
这可以手动或以通用方式完成。Sub下面我实现了一种通用方式，通过从模板继承将加入逻辑添加到子机JoinSM。
Sub有 3 个正交区域（在这个简单的示例中，每个区域仅包含一个状态，即Orthogonal1和Orthogonal2）Orthogonal3。所有这些正交状态都连接到状态，但在 中没有指定从状态Join到状态的直接连接。ExitJoinSub
此连接在JoinSM. 每次Join从 到达状态时Sub，Waiting都会激活状态并递增计数器。如果计数器达到正交区域的数量，AllJoined则触发事件并Exit激活转换。
由于JoinSM通过 的大小查询正交区域的数量initial_state，因此添加或删除区域Sub将自动反映在连接逻辑中。
#include <iostream>
#include <cstdlib>
#include <memory>
#include <cxxabi.h>
template <class T>
std::string demangle()
{
const char* name = typeid(T).name();
int status = -1;
std::unique_ptr<char, void(*)(void*)> res {
abi::__cxa_demangle(name, NULL, NULL, &status),
std::free
};
return (status==0) ? res.get() : name ;
}
#include <boost/msm/back/state_machine.hpp>
#include <boost/msm/front/state_machine_def.hpp>
#include <boost/msm/front/functor_row.hpp>
#include <boost/msm/back/metafunctions.hpp>
#include <boost/mpl/assert.hpp>
using namespace boost::msm;
using namespace boost::msm::front;
template <typename State>
struct BaseState : public boost::msm::front::state<>
{
template <class Event,class FSM> void on_entry(Event const&,FSM& )
{
std::cout << "on_entry: " << demangle<State>() << std::endl;
}
template <class Event,class FSM> void on_exit(Event const&,FSM& )
{
std::cout << "on_exit: " << demangle<State>() << std::endl;
}
};
// EVENTS
struct EnterOrthogonal {};
struct Orthogonal1Finished{};
struct Orthogonal2Finished{};
struct Orthogonal3Finished{};
struct SubSM_ : state_machine_def<SubSM_>
{
struct Started : BaseState<Started>{};
struct Exit : exit_pseudo_state<none> {};
struct Orthogonal1 : BaseState<Orthogonal1>{};
struct Orthogonal2 : BaseState<Orthogonal2>{};
struct Orthogonal3 : BaseState<Orthogonal3>{};
struct Join : BaseState<Join>{};
typedef boost::mpl::vector<Orthogonal1, Orthogonal2, Orthogonal3> initial_state;
struct transition_table : boost::mpl::vector<
Row<Orthogonal1, Orthogonal1Finished, Join, none, none>,
Row<Orthogonal2, Orthogonal2Finished, Join, none, none>,
Row<Orthogonal3, Orthogonal3Finished, Join, none, none>
> {};
};
template <typename SM, typename JoinState = typename SM::Join, typename ExitState = typename SM::Exit>
struct JoinSM : SM
{
struct AllJoined{};
constexpr static int num_regions = boost::mpl::size<typename SM::initial_state>::value;
int count;
template <class Event,class FSM>
void on_entry(Event const& ,FSM&)
{
// reset count
count = 0;
}
struct Waiting : BaseState<Waiting>
{
template <class Event,class FSM>
void on_entry(const Event& e,FSM& f)
{
BaseState<Waiting>::on_entry(e,f);
f.count++;
if (f.count == FSM::num_regions)
{
f.process_event(AllJoined());
}
}
};
typedef boost::mpl::vector<
Row<JoinState, none, Waiting, none, none>,
Row<Waiting, AllJoined, ExitState, none, none>
> additional_transition_table;
typedef boost::mpl::joint_view<
typename SM::transition_table,
additional_transition_table
> transition_table;
};
// inherit from JoinSM to add the joining logic
using Sub = back::state_machine<JoinSM<SubSM_>>;
struct MainSM_ : state_machine_def<MainSM_>
{
struct Started : BaseState<Started>{};
struct AfterJoin : BaseState<AfterJoin>{};
using initial_state = boost::mpl::vector<Started>;
struct transition_table : boost::mpl::vector<
Row<Started, EnterOrthogonal, Sub, none, none>,
Row<Sub::exit_pt<SubSM_::Exit>, none, AfterJoin, none, none>
> {};
};
struct MainSM_;
using Main = back::state_machine<MainSM_>;
int main()
{
Main main;
main.start();
main.process_event(EnterOrthogonal());
main.process_event(Orthogonal3Finished());
main.process_event(Orthogonal1Finished());
main.process_event(Orthogonal2Finished());
}
输出：
on_entry: MainSM_::Started
on_exit: MainSM_::Started
on_entry: SubSM_::Orthogonal1
on_entry: SubSM_::Orthogonal2
on_entry: SubSM_::Orthogonal3
on_exit: SubSM_::Orthogonal3
on_entry: SubSM_::Join
on_exit: SubSM_::Join
on_entry: JoinSM<SubSM_, SubSM_::Join, SubSM_::Exit>::Waiting
on_exit: SubSM_::Orthogonal1
on_entry: SubSM_::Join
on_exit: SubSM_::Join
on_entry: JoinSM<SubSM_, SubSM_::Join, SubSM_::Exit>::Waiting
on_exit: SubSM_::Orthogonal2
on_entry: SubSM_::Join
on_exit: SubSM_::Join
on_entry: JoinSM<SubSM_, SubSM_::Join, SubSM_::Exit>::Waiting
on_exit: JoinSM<SubSM_, SubSM_::Join, SubSM_::Exit>::Waiting
on_exit: JoinSM<SubSM_, SubSM_::Join, SubSM_::Exit>::Waiting
on_exit: JoinSM<SubSM_, SubSM_::Join, SubSM_::Exit>::Waiting
on_entry: MainSM_::AfterJoin
于 2015-06-19T16:12:12.283 回答