result.hpp
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#ifndef BOOST_STATECHART_RESULT_HPP_INCLUDED
#define BOOST_STATECHART_RESULT_HPP_INCLUDED
//////////////////////////////////////////////////////////////////////////////
// Copyright 2002-2010 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)
//////////////////////////////////////////////////////////////////////////////
#include <boost/assert.hpp>
namespace boost
{
namespace statechart
{
namespace detail
{
//////////////////////////////////////////////////////////////////////////////
enum reaction_result
{
no_reaction,
do_forward_event,
do_discard_event,
do_defer_event,
consumed
};
struct result_utility;
//////////////////////////////////////////////////////////////////////////////
class safe_reaction_result
{
public:
//////////////////////////////////////////////////////////////////////////
safe_reaction_result( const safe_reaction_result & other ) :
reactionResult_( other.reactionResult_ )
{
// This assert fails when an attempt is made to make multiple copies of
// a result value. This makes little sense, given the requirement that
// an obtained result value must be returned out of the react function.
BOOST_ASSERT( reactionResult_ != consumed );
other.reactionResult_ = consumed;
}
~safe_reaction_result()
{
// This assert fails when an obtained result value is not returned out
// of the react() function. This can happen if the user accidentally
// makes more than one call to reaction functions inside react() or
// accidentally makes one or more calls to reaction functions outside
// react()
BOOST_ASSERT( reactionResult_ == consumed );
}
private:
//////////////////////////////////////////////////////////////////////////
safe_reaction_result( reaction_result reactionResult ) :
reactionResult_( reactionResult )
{
}
operator reaction_result() const
{
const reaction_result val = reactionResult_;
reactionResult_ = consumed;
return val;
}
safe_reaction_result & operator=( const safe_reaction_result & );
mutable reaction_result reactionResult_;
friend struct result_utility;
};
} // namespace detail
#ifdef NDEBUG
typedef detail::reaction_result result;
#else
typedef detail::safe_reaction_result result;
#endif
namespace detail
{
//////////////////////////////////////////////////////////////////////////////
struct result_utility
{
static ::boost::statechart::result make_result( reaction_result value )
{
return value;
}
static reaction_result get_result( ::boost::statechart::result value )
{
return value;
}
};
} // namespace detail
} // namespace statechart
} // namespace boost
#endif