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102 lines
4.0 KiB
102 lines
4.0 KiB
#if !defined(BOOST_PROTO_DONT_USE_PREPROCESSED_FILES)
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#include <boost/proto/transform/detail/preprocessed/when.hpp>
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#elif !defined(BOOST_PP_IS_ITERATING)
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#if defined(__WAVE__) && defined(BOOST_PROTO_CREATE_PREPROCESSED_FILES)
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#pragma wave option(preserve: 2, line: 0, output: "preprocessed/when.hpp")
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#endif
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///////////////////////////////////////////////////////////////////////////////
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/// \file when.hpp
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/// Definition of when transform.
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//
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// Copyright 2008 Eric Niebler. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#if defined(__WAVE__) && defined(BOOST_PROTO_CREATE_PREPROCESSED_FILES)
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#pragma wave option(preserve: 1)
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#endif
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#define BOOST_PP_ITERATION_PARAMS_1 \
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(3, (0, BOOST_PROTO_MAX_ARITY, <boost/proto/transform/detail/when.hpp>))
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#include BOOST_PP_ITERATE()
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#if defined(__WAVE__) && defined(BOOST_PROTO_CREATE_PREPROCESSED_FILES)
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#pragma wave option(output: null)
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#endif
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#else
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#define N BOOST_PP_ITERATION()
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/// \brief A grammar element and a PrimitiveTransform that associates
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/// a transform with the grammar.
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///
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/// Use <tt>when\<\></tt> to override a grammar's default transform
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/// with a custom transform. It is for used when composing larger
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/// transforms by associating smaller transforms with individual
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/// rules in your grammar, as in the following transform which
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/// counts the number of terminals in an expression.
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///
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/// \code
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/// // Count the terminals in an expression tree.
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/// // Must be invoked with initial state == mpl::int_<0>().
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/// struct CountLeaves
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/// : or_<
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/// when<terminal<_>, mpl::next<_state>()>
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/// , otherwise<fold<_, _state, CountLeaves> >
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/// >
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/// {};
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/// \endcode
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///
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/// The <tt>when\<G, R(A0,A1,...)\></tt> form accepts either a
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/// CallableTransform or an ObjectTransform as its second parameter.
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/// <tt>when\<\></tt> uses <tt>is_callable\<R\>::value</tt> to
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/// distinguish between the two, and uses <tt>call\<\></tt> to
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/// evaluate CallableTransforms and <tt>make\<\></tt> to evaluate
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/// ObjectTransforms.
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template<typename Grammar, typename R BOOST_PP_ENUM_TRAILING_PARAMS(N, typename A)>
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struct when<Grammar, R(BOOST_PP_ENUM_PARAMS(N, A))>
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: detail::when_impl<Grammar, R, R(BOOST_PP_ENUM_PARAMS(N, A))>
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{};
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#if N > 0
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/// \brief A grammar element and a PrimitiveTransform that associates
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/// a transform with the grammar.
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///
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/// Use <tt>when\<\></tt> to override a grammar's default transform
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/// with a custom transform. It is for used when composing larger
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/// transforms by associating smaller transforms with individual
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/// rules in your grammar, as in the following transform which
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/// counts the number of terminals in an expression.
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///
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/// \code
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/// // Count the terminals in an expression tree.
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/// // Must be invoked with initial state == mpl::int_<0>().
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/// struct CountLeaves
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/// : or_<
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/// when<terminal<_>, mpl::next<_state>()>
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/// , otherwise<fold<_, _state, CountLeaves> >
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/// >
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/// {};
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/// \endcode
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///
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/// The <tt>when\<G, R(A0,A1,...)\></tt> form accepts either a
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/// CallableTransform or an ObjectTransform as its second parameter.
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/// <tt>when\<\></tt> uses <tt>is_callable\<R\>::value</tt> to
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/// distinguish between the two, and uses <tt>call\<\></tt> to
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/// evaluate CallableTransforms and <tt>make\<\></tt> to evaluate
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/// ObjectTransforms.
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template<typename Grammar, typename R BOOST_PP_ENUM_TRAILING_PARAMS(N, typename A)>
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struct when<Grammar, R(BOOST_PP_ENUM_PARAMS(N, A)...)>
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: detail::when_impl<Grammar, R, R(BOOST_PP_ENUM_PARAMS(N, A)...)>
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{};
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#endif
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#undef N
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#endif
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