libs/mpl/example/fsm/state_machine.hpp

   1
   2 #ifndef BOOST_FSM_STATE_MACHINE_INCLUDED
   3 #define BOOST_FSM_STATE_MACHINE_INCLUDED
   4
   5 // Copyright Aleksey Gurtovoy 2002-2004
   6 //
   7 // Distributed under the Boost Software License, Version 1.0.
   8 // (See accompanying file LICENSE_1_0.txt or copy at
   9 // http://www.boost.org/LICENSE_1_0.txt)
  10 //
  11 // See http://www.boost.org/libs/mpl for documentation.
  12
  13 // $Id$
  14 // $Date$
  15 // $Revision$
  16
  17 #include "aux_/event.hpp"
  18 #include "aux_/state.hpp"
  19 #include "aux_/transition.hpp"
  20 #include "aux_/STT_impl_gen.hpp"
  21 #include <boost/shared_ptr.hpp>
  22
  23 #include <queue>
  24 #include <memory>
  25 #include <cassert>
  26
  27 namespace fsm {
  28
  29 template< typename Derived >
  30 class state_machine
  31 {
  32  private:
  33     typedef state_machine self_t;
  34     typedef aux::base_event base_event_t;
  35     typedef boost::shared_ptr<base_event_t const> base_event_ptr_t;
  36
  37  public:
  38     typedef long state_t;
  39     typedef void (Derived::* invariant_func_t)() const;
  40
  41     template< typename DerivedEvent >
  42     struct event
  43         : aux::event<DerivedEvent>
  44     {
  45     };
  46
  47     void process_event(base_event_t const& evt)
  48     {
  49         // all internal events should be handled at this point
  50         assert(!m_events_queue.size());
  51
  52         // process the external event passed
  53         do_transition(evt);
  54
  55         // if the previous transition generated any internal events,
  56         // process those
  57         while (m_events_queue.size())
  58         {
  59             do_transition(*m_events_queue.front());
  60             m_events_queue.pop();
  61         }
  62     }
  63
  64     state_t current_state() const
  65     {
  66         return m_state;
  67     }
  68
  69  protected:
  70     // interface for the derived class
  71
  72     state_machine(state_t const& initial_state)
  73         : m_state(initial_state)
  74     {
  75     }
  76
  77     state_machine()
  78         : m_state(typename Derived::initial_state())
  79     {
  80     }
  81
  82     virtual ~state_machine()
  83     {
  84     }
  85
  86     void post_event(std::auto_ptr<base_event_t const> evt)
  87     {
  88         m_events_queue.push(base_event_ptr_t(evt.release()));
  89     }
  90
  91     template<
  92           long State
  93 #if !defined(BOOST_INTEL_CXX_VERSION) && (!defined(__GNUC__) || __GNUC__ >= 3)
  94         , invariant_func_t f = static_cast<invariant_func_t>(0)
  95 #else
  96         , invariant_func_t f = 0
  97 #endif
  98         >
  99     struct state
 100         : fsm::aux::state<Derived,State,f>
 101     {
 102     };
 103
 104     template<
 105           typename From
 106         , typename Event
 107         , typename To
 108         , bool (Derived::* transition_func)(Event const&)
 109         >
 110     struct transition
 111         : aux::transition< Derived,From,Event,To,transition_func >
 112     {
 113     };
 114
 115  private:
 116
 117     void do_transition(base_event_t const& evt)
 118     {
 119         typedef typename Derived::transition_table STT_;
 120         typedef typename aux::STT_impl_gen< STT_ >::type STT_impl_;
 121
 122         m_state = STT_impl_::do_transition(
 123               static_cast<Derived&>(*this)
 124             , m_state
 125             , evt
 126             );
 127     }
 128
 129     state_t m_state;
 130     std::queue< base_event_ptr_t > m_events_queue;
 131 };
 132
 133 } // namespace fsm
 134
 135 #endif // BOOST_FSM_STATE_MACHINE_INCLUDED