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- //////////////////////////////////////////////////////////////////////////////
- // Copyright 2002-2006 Andreas Huber Doenni
- // Distributed under the Boost Software License, Version 1.0. (See accompany-
- // ing file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- //////////////////////////////////////////////////////////////////////////////
- //////////////////////////////////////////////////////////////////////////////
- #define NO_OF_BITS 3
- //////////////////////////////////////////////////////////////////////////////
- // This program demonstrates the fact that measures must be taken to hide some
- // of the complexity (e.g. in separate .cpp file) of a Boost.Statechart state
- // machine once a certain size is reached.
- // For this purpose, a state machine with exactly 2^NO_OF_BITS states (i.e.
- // BitState< 0 > .. BitState< 2^NO_OF_BITS - 1 >) is generated. For the events
- // EvFlipBit< 0 > .. EvFlipBit< NO_OF_BITS - 1 > there is a transition from
- // each state to the state with the corresponding bit toggled. That is, there
- // is a total of 2^NO_OF_BITS * NO_OF_BITS transitions.
- // E.g. if the state machine is currently in state BitState< 5 > and receives
- // EvFlipBit< 2 >, it transitions to state BitState< 1 >. If it is in
- // BitState< 15 > and receives EvFlipBit< 4 > it transitions to BitState< 31 >
- // etc.
- // The maximum size of such a state machine depends on your compiler. The
- // following table gives upper limits for NO_OF_BITS. From this, rough
- // estimates for the maximum size of any "naively" implemented Boost.Statechart
- // machine (i.e. no attempt is made to hide inner state implementation in a
- // .cpp file) can be deduced.
- //
- // NOTE: Due to the fact that the amount of generated code more than
- // *doubles* each time NO_OF_BITS is *incremented*, build times on most
- // compilers soar when NO_OF_BITS > 6.
- //
- // Compiler | max. NO_OF_BITS b | max. states s |
- // --------------|-------------------|----------------|
- // MSVC 7.1 | b < 6 | 32 < s < 64 |
- // GCC 3.4.2 (1) | b < 8 | 128 < s < 256 |
- //
- // (1) This is a practical rather than a hard limit, caused by a compiler
- // memory footprint that was significantly larger than the 1GB physical
- // memory installed in the test machine. The resulting frequent swapping
- // led to compilation times of hours rather than minutes.
- //////////////////////////////////////////////////////////////////////////////
- #include "UniqueObject.hpp"
- #include <boost/statechart/event.hpp>
- #include <boost/statechart/simple_state.hpp>
- #include <boost/statechart/state_machine.hpp>
- #include <boost/statechart/transition.hpp>
- #include <boost/mpl/list.hpp>
- #include <boost/mpl/front_inserter.hpp>
- #include <boost/mpl/transform_view.hpp>
- #include <boost/mpl/copy.hpp>
- #include <boost/mpl/range_c.hpp>
- #include <boost/mpl/integral_c.hpp>
- #include <boost/mpl/shift_left.hpp>
- #include <boost/mpl/bitxor.hpp>
- #include <boost/mpl/for_each.hpp>
- #include <boost/mpl/placeholders.hpp>
- #include <boost/mpl/aux_/lambda_support.hpp>
- #include <boost/config.hpp>
- #include <boost/intrusive_ptr.hpp>
- #include <iostream>
- #include <iomanip>
- #include <cstddef> // size_t
- #ifdef BOOST_INTEL
- # pragma warning( disable: 304 ) // access control not specified
- # pragma warning( disable: 444 ) // destructor for base is not virtual
- # pragma warning( disable: 981 ) // operands are evaluated in unspecified order
- #endif
- namespace sc = boost::statechart;
- namespace mpl = boost::mpl;
- //////////////////////////////////////////////////////////////////////////////
- struct IDisplay
- {
- virtual void Display() const = 0;
- };
- //////////////////////////////////////////////////////////////////////////////
- template< class BitNo >
- struct EvFlipBit : sc::event< EvFlipBit< BitNo > > {};
- template< class StateNo >
- struct BitState;
- struct BitMachine : sc::state_machine<
- BitMachine, BitState< mpl::integral_c< unsigned int, 0 > > > {};
- template< class BitNo, class StateNo >
- struct FlipTransition
- {
- private:
- typedef typename mpl::bitxor_<
- StateNo,
- mpl::shift_left< mpl::integral_c< unsigned int, 1 >, BitNo >
- >::type NextStateNo;
- public:
- typedef typename sc::transition<
- EvFlipBit< BitNo >, BitState< NextStateNo > > type;
- BOOST_MPL_AUX_LAMBDA_SUPPORT( 2, FlipTransition, (BitNo, StateNo) );
- };
- //////////////////////////////////////////////////////////////////////////////
- void DisplayBits( unsigned int number )
- {
- char buffer[ NO_OF_BITS + 1 ];
- buffer[ NO_OF_BITS ] = 0;
- for ( unsigned int bit = 0; bit < NO_OF_BITS; ++bit )
- {
- buffer[ bit ] = number & ( 1 << ( NO_OF_BITS - bit - 1 ) ) ? '1' : '0';
- }
- std::cout << "Current state: " << std::setw( 4 ) <<
- number << " (" << buffer << ")" << std::endl;
- }
- template< class StateNo >
- struct BitState : sc::simple_state< BitState< StateNo >, BitMachine >,
- UniqueObject< BitState< StateNo > >, IDisplay
- {
- void * operator new( std::size_t size )
- {
- return UniqueObject< BitState< StateNo > >::operator new( size );
- }
- void operator delete( void * p, std::size_t size )
- {
- UniqueObject< BitState< StateNo > >::operator delete( p, size );
- }
- typedef typename mpl::copy<
- typename mpl::transform_view<
- mpl::range_c< unsigned int, 0, NO_OF_BITS >,
- FlipTransition< mpl::placeholders::_, StateNo > >::type,
- mpl::front_inserter< mpl::list<> >
- >::type reactions;
- virtual void Display() const
- {
- DisplayBits( StateNo::value );
- }
- };
- void DisplayMachineState( const BitMachine & bitMachine )
- {
- bitMachine.state_cast< const IDisplay & >().Display();
- }
- //////////////////////////////////////////////////////////////////////////////
- boost::intrusive_ptr< const sc::event_base > pFlipBitEvents[ NO_OF_BITS ];
- struct EventInserter
- {
- template< class BitNo >
- void operator()( const BitNo & )
- {
- pFlipBitEvents[ BitNo::value ] = new EvFlipBit< BitNo >();
- }
- };
- void FillEventArray()
- {
- mpl::for_each< mpl::range_c< unsigned int, 0, NO_OF_BITS > >(
- EventInserter() );
- }
- //////////////////////////////////////////////////////////////////////////////
- void VisitAllStates( BitMachine & bitMachine, unsigned int msb )
- {
- if ( msb > 0 )
- {
- VisitAllStates( bitMachine, msb - 1 );
- }
- bitMachine.process_event( *pFlipBitEvents[ msb ] );
- DisplayMachineState( bitMachine );
- if ( msb > 0 )
- {
- VisitAllStates( bitMachine, msb - 1 );
- }
- }
- //////////////////////////////////////////////////////////////////////////////
- char GetKey()
- {
- char key;
- std::cin >> key;
- return key;
- }
- //////////////////////////////////////////////////////////////////////////////
- int main()
- {
- FillEventArray();
- const unsigned int noOfStates = 1 << NO_OF_BITS;
- std::cout << "Boost.Statechart BitMachine example\n";
- std::cout << "Machine configuration: " << noOfStates <<
- " states interconnected with " << noOfStates * NO_OF_BITS <<
- " transitions.\n\n";
- for ( unsigned int bit = 0; bit < NO_OF_BITS; ++bit )
- {
- std::cout << bit - 0 << "<CR>: Flips bit " << bit - 0 << "\n";
- }
- std::cout << "a<CR>: Goes through all states automatically\n";
- std::cout << "e<CR>: Exits the program\n\n";
- std::cout << "You may chain commands, e.g. 31<CR> flips bits 3 and 1\n\n";
- BitMachine bitMachine;
- bitMachine.initiate();
- char key = GetKey();
- while ( key != 'e' )
- {
- if ( ( key >= '0' ) && ( key < static_cast< char >( '0' + NO_OF_BITS ) ) )
- {
- bitMachine.process_event( *pFlipBitEvents[ key - '0' ] );
- DisplayMachineState( bitMachine );
- }
- else
- {
- switch( key )
- {
- case 'a':
- {
- VisitAllStates( bitMachine, NO_OF_BITS - 1 );
- }
- break;
- default:
- {
- std::cout << "Invalid key!\n";
- }
- }
- }
- key = GetKey();
- }
- return 0;
- }
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