| /////////////////////////////////////////////////////////////////////////////// |
| /// \file make.hpp |
| /// Contains definition of the make<> 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) |
| |
| #ifndef BOOST_PROTO_TRANSFORM_MAKE_HPP_EAN_12_02_2007 |
| #define BOOST_PROTO_TRANSFORM_MAKE_HPP_EAN_12_02_2007 |
| |
| #include <boost/detail/workaround.hpp> |
| #include <boost/preprocessor/repetition/enum.hpp> |
| #include <boost/preprocessor/repetition/enum_params.hpp> |
| #include <boost/preprocessor/repetition/enum_trailing_params.hpp> |
| #include <boost/preprocessor/repetition/enum_binary_params.hpp> |
| #include <boost/preprocessor/repetition/enum_params_with_a_default.hpp> |
| #include <boost/preprocessor/repetition/repeat_from_to.hpp> |
| #include <boost/preprocessor/facilities/intercept.hpp> |
| #include <boost/preprocessor/cat.hpp> |
| #include <boost/preprocessor/iteration/iterate.hpp> |
| #include <boost/preprocessor/selection/max.hpp> |
| #include <boost/preprocessor/arithmetic/inc.hpp> |
| #include <boost/mpl/and.hpp> |
| #include <boost/mpl/aux_/has_type.hpp> |
| #include <boost/proto/detail/template_arity.hpp> |
| #include <boost/utility/result_of.hpp> |
| #include <boost/proto/proto_fwd.hpp> |
| #include <boost/proto/traits.hpp> |
| #include <boost/proto/args.hpp> |
| #include <boost/proto/transform/impl.hpp> |
| #include <boost/proto/transform/detail/pack.hpp> |
| #include <boost/proto/detail/as_lvalue.hpp> |
| #include <boost/proto/detail/ignore_unused.hpp> |
| |
| #if defined(_MSC_VER) |
| # pragma warning(push) |
| # pragma warning(disable : 4714) // function 'xxx' marked as __forceinline not inlined |
| #endif |
| |
| namespace boost { namespace proto |
| { |
| namespace detail |
| { |
| template<typename T> |
| struct is_applyable |
| : mpl::and_<is_callable<T>, is_transform<T> > |
| {}; |
| |
| template<typename T, bool HasType = mpl::aux::has_type<T>::value> |
| struct nested_type |
| { |
| typedef typename T::type type; |
| }; |
| |
| template<typename T> |
| struct nested_type<T, false> |
| { |
| typedef T type; |
| }; |
| |
| template<typename T, bool Applied> |
| struct nested_type_if |
| { |
| typedef T type; |
| static bool const applied = false; |
| }; |
| |
| template<typename T> |
| struct nested_type_if<T, true> |
| : nested_type<T> |
| { |
| static bool const applied = true; |
| }; |
| |
| template< |
| typename R |
| , typename Expr, typename State, typename Data |
| BOOST_PROTO_TEMPLATE_ARITY_PARAM(long Arity = detail::template_arity<R>::value) |
| > |
| struct make_ |
| { |
| typedef R type; |
| static bool const applied = false; |
| }; |
| |
| template< |
| typename R |
| , typename Expr, typename State, typename Data |
| , bool IsApplyable = is_applyable<R>::value |
| > |
| struct make_if_ |
| : make_<R, Expr, State, Data> |
| {}; |
| |
| template<typename R, typename Expr, typename State, typename Data> |
| struct make_if_<R, Expr, State, Data, true> |
| : uncvref<typename when<_, R>::template impl<Expr, State, Data>::result_type> |
| { |
| static bool const applied = true; |
| }; |
| |
| #if BOOST_WORKAROUND(__GNUC__, == 3) || (BOOST_WORKAROUND(__GNUC__, == 4) && __GNUC_MINOR__ == 0) |
| // work around GCC bug |
| template<typename Tag, typename Args, long N, typename Expr, typename State, typename Data> |
| struct make_if_<proto::expr<Tag, Args, N>, Expr, State, Data, false> |
| { |
| typedef proto::expr<Tag, Args, N> type; |
| static bool const applied = false; |
| }; |
| |
| // work around GCC bug |
| template<typename Tag, typename Args, long N, typename Expr, typename State, typename Data> |
| struct make_if_<proto::basic_expr<Tag, Args, N>, Expr, State, Data, false> |
| { |
| typedef proto::basic_expr<Tag, Args, N> type; |
| static bool const applied = false; |
| }; |
| #endif |
| |
| template<typename Type, bool IsAggregate = detail::is_aggregate_<Type>::value> |
| struct construct_ |
| { |
| typedef Type result_type; |
| |
| BOOST_FORCEINLINE |
| Type operator ()() const |
| { |
| return Type(); |
| } |
| |
| // Other overloads generated by the preprocessor |
| #include <boost/proto/transform/detail/construct_funop.hpp> |
| }; |
| |
| template<typename Type> |
| struct construct_<Type, true> |
| { |
| typedef Type result_type; |
| |
| BOOST_FORCEINLINE |
| Type operator ()() const |
| { |
| return Type(); |
| } |
| |
| // Other overloads generated by the preprocessor |
| #include <boost/proto/transform/detail/construct_pod_funop.hpp> |
| }; |
| |
| } |
| |
| /// \brief A PrimitiveTransform which prevents another PrimitiveTransform |
| /// from being applied in an \c ObjectTransform. |
| /// |
| /// When building higher order transforms with <tt>make\<\></tt> or |
| /// <tt>lazy\<\></tt>, you sometimes would like to build types that |
| /// are parameterized with Proto transforms. In such lambda-style |
| /// transforms, Proto will unhelpfully find all nested transforms |
| /// and apply them, even if you don't want them to be applied. Consider |
| /// the following transform, which will replace the \c _ in |
| /// <tt>Bar<_>()</tt> with <tt>proto::terminal\<int\>::type</tt>: |
| /// |
| /// \code |
| /// template<typename T> |
| /// struct Bar |
| /// {}; |
| /// |
| /// struct Foo |
| /// : proto::when<_, Bar<_>() > |
| /// {}; |
| /// |
| /// proto::terminal<int>::type i = {0}; |
| /// |
| /// int main() |
| /// { |
| /// Foo()(i); |
| /// std::cout << typeid(Foo()(i)).name() << std::endl; |
| /// } |
| /// \endcode |
| /// |
| /// If you actually wanted to default-construct an object of type |
| /// <tt>Bar\<_\></tt>, you would have to protect the \c _ to prevent |
| /// it from being applied. You can use <tt>proto::protect\<\></tt> |
| /// as follows: |
| /// |
| /// \code |
| /// // OK: replace anything with Bar<_>() |
| /// struct Foo |
| /// : proto::when<_, Bar<protect<_> >() > |
| /// {}; |
| /// \endcode |
| template<typename PrimitiveTransform> |
| struct protect : transform<protect<PrimitiveTransform> > |
| { |
| template<typename, typename, typename> |
| struct impl |
| { |
| typedef PrimitiveTransform result_type; |
| }; |
| }; |
| |
| /// \brief A PrimitiveTransform which computes a type by evaluating any |
| /// nested transforms and then constructs an object of that type. |
| /// |
| /// The <tt>make\<\></tt> transform checks to see if \c Object is a template. |
| /// If it is, the template type is disassembled to find nested transforms. |
| /// Proto considers the following types to represent transforms: |
| /// |
| /// \li Function types |
| /// \li Function pointer types |
| /// \li Types for which <tt>proto::is_callable\< type \>::value</tt> is \c true |
| /// |
| /// <tt>boost::result_of\<make\<T\<X0,X1,...\> \>(Expr, State, Data)\>::type</tt> |
| /// is evaluated as follows. For each \c X in <tt>X0,X1,...</tt>, do: |
| /// |
| /// \li If \c X is a template like <tt>U\<Y0,Y1,...\></tt>, then let <tt>X'</tt> |
| /// be <tt>boost::result_of\<make\<U\<Y0,Y1,...\> \>(Expr, State, Data)\>::type</tt> |
| /// (which evaluates this procedure recursively). Note whether any |
| /// substitutions took place during this operation. |
| /// \li Otherwise, if \c X is a transform, then let <tt>X'</tt> be |
| /// <tt>boost::result_of\<when\<_, X\>(Expr, State, Data)\>::type</tt>. |
| /// Note that a substitution took place. |
| /// \li Otherwise, let <tt>X'</tt> be \c X, and note that no substitution |
| /// took place. |
| /// \li If any substitutions took place in any of the above steps and |
| /// <tt>T\<X0',X1',...\></tt> has a nested <tt>::type</tt> typedef, |
| /// the result type is <tt>T\<X0',X1',...\>::type</tt>. |
| /// \li Otherwise, the result type is <tt>T\<X0',X1',...\></tt>. |
| /// |
| /// Note that <tt>when\<\></tt> is implemented in terms of <tt>call\<\></tt> |
| /// and <tt>make\<\></tt>, so the above procedure is evaluated recursively. |
| template<typename Object> |
| struct make : transform<make<Object> > |
| { |
| template<typename Expr, typename State, typename Data> |
| struct impl : transform_impl<Expr, State, Data> |
| { |
| typedef typename detail::make_if_<Object, Expr, State, Data>::type result_type; |
| |
| /// \return <tt>result_type()</tt> |
| BOOST_FORCEINLINE |
| result_type operator ()( |
| typename impl::expr_param |
| , typename impl::state_param |
| , typename impl::data_param |
| ) const |
| { |
| return result_type(); |
| } |
| }; |
| }; |
| |
| /// INTERNAL ONLY |
| template<typename Fun> |
| struct make<detail::msvc_fun_workaround<Fun> > |
| : make<Fun> |
| {}; |
| |
| // Other specializations generated by the preprocessor. |
| #include <boost/proto/transform/detail/make.hpp> |
| #include <boost/proto/transform/detail/make_gcc_workaround.hpp> |
| |
| /// INTERNAL ONLY |
| /// |
| template<typename Object> |
| struct is_callable<make<Object> > |
| : mpl::true_ |
| {}; |
| |
| /// INTERNAL ONLY |
| /// |
| template<typename PrimitiveTransform> |
| struct is_callable<protect<PrimitiveTransform> > |
| : mpl::true_ |
| {}; |
| |
| }} |
| |
| #if defined(_MSC_VER) |
| # pragma warning(pop) |
| #endif |
| |
| #endif |