如何将增强MSM与增强信号结合使用?

How to Use boost msm combined with boost signal?

本文关键字：增强 结合 信号 MSM      更新时间：2023-10-16

我对"增强msm"真的很陌生，现在我遇到了一个问题，如何在增强msm中使用增强信号，我已经尝试了很多次，但没有工作。

我想要实现的是，当机器改变其状态时，动作操作员发出信号，我的外部实体捕获信号并继续其他功能，但现在我无法将信号发送到机器外，我无法将信号与外部实体连接。 有没有例子？

你可以组合使用Boost.Signals2和Boost.MSM。

下面是简单的 signals2 示例。

https://wandbox.org/permlink/XZzGIIVWXjvOPzdd(运行演示(

#include <iostream>
#include <string>
#include <boost/signals2/signal.hpp>
#include <iostream>
// begin -- signals2 code
struct signal_data {
int i;
std::string str;
};
struct sender {
boost::signals2::signal<void(signal_data const&)> foo;
void send() {
foo(signal_data {42, "ABC"} );
}
};
struct receiver_1 {
void on_foo(signal_data const& sd) {
std::cout << __PRETTY_FUNCTION__ << " " << sd.i << ", " << sd.str << std::endl;
}
};
struct receiver_2 {
void on_foo(signal_data const& sd) {
std::cout << __PRETTY_FUNCTION__ << " " << sd.i << ", " << sd.str << std::endl;
}
};
// end -- signals2 code
int main() {
// signals setup ----------------------------------------
// external entities
receiver_1 r1;
receiver_2 r2;
sender s;
// make connection
// using lambda expression
s.foo.connect(
[&] (signal_data const& param) {
r1.on_foo(param);
}
);
// or bind
s.foo.connect(std::bind(&receiver_2::on_foo, &r2, std::placeholders::_1));
s.send();
}

信号发送点s.send()。如果我们能从MSM的行动中呼唤s.send()，目标就会实现。

这是简单的 msm 示例。

https://wandbox.org/permlink/tnRSQ07anNe49GpO(运行演示(

#include <iostream>
#include <string>
#include <boost/msm/back/state_machine.hpp>
#include <boost/msm/front/state_machine_def.hpp>
#include <boost/msm/front/functor_row.hpp>
// begin -- msm code
namespace msm = boost::msm;
namespace msmf = boost::msm::front;
namespace mpl = boost::mpl;
// ----- Events
struct event1 {};
// ----- State machine
struct sm1_:msmf::state_machine_def<sm1_> {
// States
struct state1:msmf::state<> {};
// Set initial state
using initial_state = state1;
// Actions
struct action {
template <class Event, class Fsm, class SourceState, class TargetState>
void operator()(Event const&, Fsm&, SourceState&, TargetState&) const {
std::cout << "action()" << std::endl;
// want to call s.send() here
}
};
// Transition table
struct transition_table:mpl::vector<
//          Start   Event   Next        Action      Guard
msmf::Row < state1, event1, msmf::none, action,     msmf::none >
> {};
};
// Pick a back-end
using sm1 = msm::back::state_machine<sm1_>;
// end -- msm code
int main() {
sm1 s1;
s1.start(); 
std::cout << "Send event1" << std::endl;
s1.process_event(event1());
}

该操作定义如下：

struct action {
template <class Event, class Fsm, class SourceState, class TargetState>
void operator()(Event const&, Fsm&, SourceState&, TargetState&) const {
std::cout << "action()" << std::endl;
// want to call s.send() here
}
};

如何在行动中调用s.send()？

首先，将发送方的引用添加为 sm1_ 的成员变量。

sender& s; // define sender reference as a member variable

然后，在构造函数中初始化它。

sm1_(sender& s):s(s) {} // initialize sender in constructor

然后，在创建状态机时传递包装std::ref发送方。

sm1 s1(std::ref(s)); // pass sender as reference

最后，在操作中调用s.send()。您可以通过Fsm引用访问s，如下所示：

struct action {
template <class Event, class Fsm, class SourceState, class TargetState>
void operator()(Event const&, Fsm& f, SourceState&, TargetState&) const {
std::cout << "action()" << std::endl;
f.s.send();
}
};

这是整个代码：

https://wandbox.org/permlink/gh83EW8eado5iOi8(运行演示(

#include <iostream>
#include <string>
#include <boost/signals2/signal.hpp>
#include <iostream>
#include <boost/msm/back/state_machine.hpp>
#include <boost/msm/front/state_machine_def.hpp>
#include <boost/msm/front/functor_row.hpp>
// begin -- signals2 code
struct signal_data {
int i;
std::string str;
};
struct sender {
boost::signals2::signal<void(signal_data const&)> foo;
void send() {
foo(signal_data {42, "ABC"} );
}
};
struct receiver_1 {
void on_foo(signal_data const& sd) {
std::cout << __PRETTY_FUNCTION__ << " " << sd.i << ", " << sd.str << std::endl;
}
};
struct receiver_2 {
void on_foo(signal_data const& sd) {
std::cout << __PRETTY_FUNCTION__ << " " << sd.i << ", " << sd.str << std::endl;
}
};
// end -- signals2 code
// begin -- msm code
namespace msm = boost::msm;
namespace msmf = boost::msm::front;
namespace mpl = boost::mpl;
// ----- Events
struct event1 {};
// ----- State machine
struct sm1_:msmf::state_machine_def<sm1_> {
sm1_(sender& s):s(s) {} // initialize sender in constructor
// States
struct state1:msmf::state<> {};
// Set initial state
using initial_state = state1;
// Actions
struct action {
template <class Event, class Fsm, class SourceState, class TargetState>
void operator()(Event const&, Fsm& f, SourceState&, TargetState&) const {
std::cout << "action()" << std::endl;
f.s.send();
}
};
// Transition table
struct transition_table:mpl::vector<
//          Start   Event   Next        Action      Guard
msmf::Row < state1, event1, msmf::none, action,     msmf::none >
> {};
sender& s; // define sender reference as a member variable
};
// Pick a back-end
using sm1 = msm::back::state_machine<sm1_>;
// end -- msm code
int main() {
// signals setup ----------------------------------------
// external entities
receiver_1 r1;
receiver_2 r2;
sender s;
// make connection
// using lambda expression
s.foo.connect(
[&] (signal_data const& param) {
r1.on_foo(param);
}
);
// or bind
s.foo.connect(std::bind(&receiver_2::on_foo, &r2, std::placeholders::_1));
// msm setup and process ---------------------------------
sm1 s1(std::ref(s)); // pass sender as reference
s1.start(); 
std::cout << "Send event1" << std::endl;
s1.process_event(event1());
}
相关文章：