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61 lines
1.6 KiB
61 lines
1.6 KiB
/*============================================================================== |
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Copyright (c) 2005-2010 Joel de Guzman |
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Distributed under the Boost Software License, Version 1.0. (See accompanying |
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
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==============================================================================*/ |
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#ifndef BOOST_PHOENIX_CORE_NOTHING_HPP |
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#define BOOST_PHOENIX_CORE_NOTHING_HPP |
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#include <boost/phoenix/core/limits.hpp> |
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#include <boost/mpl/void.hpp> |
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#include <boost/phoenix/core/actor.hpp> |
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#include <boost/phoenix/core/call.hpp> |
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#include <boost/phoenix/core/expression.hpp> |
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#include <boost/phoenix/core/value.hpp> |
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namespace boost { namespace phoenix |
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{ |
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///////////////////////////////////////////////////////////////////////////// |
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// |
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// null_actor |
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// |
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// An actor that does nothing (a "bum", if you will :-). |
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// |
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///////////////////////////////////////////////////////////////////////////// |
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namespace detail |
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{ |
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struct nothing {}; |
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} |
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namespace expression |
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{ |
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struct null |
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: expression::value<detail::nothing> |
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{}; |
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} |
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template<typename Dummy> |
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struct is_custom_terminal<detail::nothing, Dummy> |
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: mpl::true_ |
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{}; |
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template<typename Dummy> |
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struct custom_terminal<detail::nothing, Dummy> |
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{ |
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typedef void result_type; |
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template <typename Context> |
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void operator()(detail::nothing, Context &) const |
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{ |
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} |
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}; |
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typedef expression::null::type nothing_type; |
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#ifndef BOOST_PHOENIX_NO_PREDEFINED_TERMINALS |
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nothing_type const nothing = {{{}}}; |
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#endif |
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}} |
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#endif
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