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