以下代码是仿函数前端的boost msm文档中给出的示例。
#include <vector>
#include <iostream>
// back-end
#include <boost/msm/back/state_machine.hpp>
//front-end
#include <boost/msm/front/state_machine_def.hpp>
// functors
#include <boost/msm/front/functor_row.hpp>
#include <boost/msm/front/euml/common.hpp>
// for And_ operator
#include <boost/msm/front/euml/operator.hpp>
// for func_state and func_state_machine
#include <boost/msm/front/euml/state_grammar.hpp>
using namespace std;
namespace msm = boost::msm;
namespace mpl = boost::mpl;
using namespace msm::front;
// for And_ operator
using namespace msm::front::euml;
namespace // Concrete FSM implementation
{
// events
struct play {};
struct end_pause {};
struct stop {};
struct pause {};
struct open_close {};
// A "complicated" event type that carries some data.
enum DiskTypeEnum
{
DISK_CD=0,
DISK_DVD=1
};
struct cd_detected
{
cd_detected(std::string name, DiskTypeEnum diskType)
: name(name),
disc_type(diskType)
{}
std::string name;
DiskTypeEnum disc_type;
};
// front-end: define the FSM structure
struct player_ : public msm::front::state_machine_def<player_>
{
// The list of FSM states
// entry and exit functors for Empty
struct Empty_Entry
{
template <class Event,class FSM,class STATE>
void operator()(Event const&,FSM&,STATE& )
{
std::cout << "entering: Empty" << std::endl;
}
};
struct Empty_Exit
{
template <class Event,class FSM,class STATE>
void operator()(Event const&,FSM&,STATE& )
{
std::cout << "leaving: Empty" << std::endl;
}
};
// definition of Empty
struct Empty_tag {};
typedef msm::front::euml::func_state<Empty_tag,Empty_Entry,Empty_Exit> Empty;
struct Open_Entry
{
template <class Event,class FSM,class STATE>
void operator()(Event const&,FSM&,STATE& )
{
std::cout << "entering: Open" << std::endl;
}
};
struct Open_Exit
{
template <class Event,class FSM,class STATE>
void operator()(Event const&,FSM&,STATE& )
{
std::cout << "leaving: Open" << std::endl;
}
};
struct Open_tag {};
typedef msm::front::euml::func_state<Open_tag,Open_Entry,Open_Exit> Open;
// states without entry/exit actions (can be declared as functor state, just without functors ;-) )
struct Stopped_tag {};
typedef msm::front::euml::func_state<Stopped_tag> Stopped;
struct Playing_tag {};
typedef msm::front::euml::func_state<Playing_tag> Playing;
// state not defining any entry or exit (declared as simple state. Equivalent)
struct Paused : public msm::front::state<>
{
};
// the initial state of the player SM. Must be defined
typedef Empty initial_state;
// transition actions
// as the functors are generic on events, fsm and source/target state,
// you can reuse them in another machine if you wish
struct TestFct
{
template <class EVT,class FSM,class SourceState,class TargetState>
void operator()(EVT const&, FSM&,SourceState& ,TargetState& )
{
cout << "transition with event:" << typeid(EVT).name() << endl;
}
};
struct start_playback
{
template <class EVT,class FSM,class SourceState,class TargetState>
void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
{
cout << "player::start_playback" << endl;
}
};
struct open_drawer
{
template <class EVT,class FSM,class SourceState,class TargetState>
void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
{
cout << "player::open_drawer" << endl;
}
};
struct close_drawer
{
template <class EVT,class FSM,class SourceState,class TargetState>
void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
{
cout << "player::close_drawer" << endl;
}
};
struct store_cd_info
{
template <class EVT,class FSM,class SourceState,class TargetState>
void operator()(EVT const&,FSM& fsm ,SourceState& ,TargetState& )
{
cout << "player::store_cd_info" << endl;
fsm.process_event(play());
}
};
struct stop_playback
{
template <class EVT,class FSM,class SourceState,class TargetState>
void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
{
cout << "player::stop_playback" << endl;
}
};
struct pause_playback
{
template <class EVT,class FSM,class SourceState,class TargetState>
void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
{
cout << "player::pause_playback" << endl;
}
};
struct resume_playback
{
template <class EVT,class FSM,class SourceState,class TargetState>
void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
{
cout << "player::resume_playback" << endl;
}
};
struct stop_and_open
{
template <class EVT,class FSM,class SourceState,class TargetState>
void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
{
cout << "player::stop_and_open" << endl;
}
};
struct stopped_again
{
template <class EVT,class FSM,class SourceState,class TargetState>
void operator()(EVT const& ,FSM& ,SourceState& ,TargetState& )
{
cout << "player::stopped_again" << endl;
}
};
// guard conditions
struct DummyGuard
{
template <class EVT,class FSM,class SourceState,class TargetState>
bool operator()(EVT const& evt,FSM& fsm,SourceState& src,TargetState& tgt)
{
return true;
}
};
struct good_disk_format
{
template <class EVT,class FSM,class SourceState,class TargetState>
bool operator()(EVT const& evt ,FSM&,SourceState& ,TargetState& )
{
// to test a guard condition, let's say we understand only CDs, not DVD
if (evt.disc_type != DISK_CD)
{
std::cout << "wrong disk, sorry" << std::endl;
return false;
}
return true;
}
};
struct always_true
{
template <class EVT,class FSM,class SourceState,class TargetState>
bool operator()(EVT const& evt ,FSM&,SourceState& ,TargetState& )
{
return true;
}
};
// we want to define one row with the classic look.
bool auto_start(cd_detected const& evt)
{
return false;
}
typedef player_ p; // makes transition table cleaner
// Transition table for player
struct transition_table : mpl::vector<
// Start Event Next Action Guard
// +---------+-------------+---------+---------------------------+----------------------+
Row < Stopped , play , Playing , ActionSequence_
<mpl::vector<
TestFct,start_playback> >
, DummyGuard >,
Row < Stopped , open_close , Open , open_drawer , none >,
Row < Stopped , stop , Stopped , none , none >,
// +---------+-------------+---------+---------------------------+----------------------+
Row < Open , open_close , Empty , close_drawer , none >,
// +---------+-------------+---------+---------------------------+----------------------+
Row < Empty , open_close , Open , open_drawer , none >,
Row < Empty , cd_detected , Stopped , store_cd_info , And_<good_disk_format,
always_true> >,
// we here also mix with some "classical row"
g_row < Empty , cd_detected , Playing , &p::auto_start >,
// +---------+-------------+---------+---------------------------+----------------------+
Row < Playing , stop , Stopped , stop_playback , none >,
Row < Playing , pause , Paused , pause_playback , none >,
Row < Playing , open_close , Open , stop_and_open , none >,
// +---------+-------------+---------+---------------------------+----------------------+
Row < Paused , end_pause , Playing , resume_playback , none >,
Row < Paused , stop , Stopped , stop_playback , none >,
Row < Paused , open_close , Open , stop_and_open , none >
// +---------+-------------+---------+---------------------------+----------------------+
> {};
// Replaces the default no-transition response.
template <class FSM,class Event>
void no_transition(Event const& e, FSM&,int state)
{
std::cout << "no transition from state " << state
<< " on event " << typeid(e).name() << std::endl;
}
};
// Pick a back-end
typedef msm::back::state_machine<player_> player;
//
// Testing utilities.
//
static char const* const state_names[] = { "Stopped", "Open", "Empty", "Playing", "Paused" };
void pstate(player const& p)
{
std::cout << " -> " << state_names[p.current_state()[0]] << std::endl;
}
void test()
{
player p;
// needed to start the highest-level SM. This will call on_entry and mark the start of the SM
p.start();
// go to Open, call on_exit on Empty, then action, then on_entry on Open
p.process_event(open_close()); pstate(p);
p.process_event(open_close()); pstate(p);
// will be rejected, wrong disk type
p.process_event(
cd_detected("louie, louie",DISK_DVD)); pstate(p);
p.process_event(
cd_detected("louie, louie",DISK_CD)); pstate(p);
// no need to call play() as the previous event does it in its action method
//p.process_event(play());
// at this point, Play is active
p.process_event(pause()); pstate(p);
// go back to Playing
p.process_event(end_pause()); pstate(p);
p.process_event(pause()); pstate(p);
p.process_event(stop()); pstate(p);
// event leading to the same state
// no action method called as it is not present in the transition table
p.process_event(stop()); pstate(p);
}
}
int main()
{
test();
return 0;
}
当我尝试构建它时，它给出的错误不在此文件中，而是在boost库文件proto中。 以下是我得到的错误
/usr/include/boost/proto/detail/poly_function.hpp:223:1: error: missing binary operator before token "("
/usr/include/boost/proto/detail/poly_function.hpp:263:1: error: missing binary operator before token "("
In file included from /usr/include/boost/proto/make_expr.hpp:45:0,
from /usr/include/boost/proto/operators.hpp:22,
from /usr/include/boost/proto/core.hpp:26,
from /usr/include/boost/msm/back/fold_to_list.hpp:14,
from /usr/include/boost/msm/back/state_machine.hpp:55,
from ../src/msmtryouts.cpp:12:
/usr/include/boost/proto/detail/poly_function.hpp:223:1: error: missing binary operator before token "("
/usr/include/boost/proto/detail/poly_function.hpp:263:1: error: missing binary operator before token "("
/usr/include/boost/proto/detail/deduce_domain.hpp:41:20: error: redefinition of ‘struct boost::proto::detail::sized_type<N>’
/usr/include/boost/proto/proto_fwd.hpp:113:16: error: previous definition of ‘struct boost::proto::detail::sized_type<N>’
make: *** [src/msmtryouts.o] Error 1
我在这里缺少什么？
答案 0 :(得分：1)
很好地找到了自己的答案。