| #ifndef BOOST_PP_IS_ITERATING |
| /////////////////////////////////////////////////////////////////////////////// |
| /// \file generate.hpp |
| /// Contains definition of generate\<\> class template, which end users can |
| /// specialize for generating domain-specific expression wrappers. |
| // |
| // 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_GENERATE_HPP_EAN_02_13_2007 |
| #define BOOST_PROTO_GENERATE_HPP_EAN_02_13_2007 |
| |
| #include <boost/config.hpp> |
| #include <boost/preprocessor/cat.hpp> |
| #include <boost/preprocessor/iteration/iterate.hpp> |
| #include <boost/preprocessor/facilities/intercept.hpp> |
| #include <boost/preprocessor/repetition/enum_params.hpp> |
| #include <boost/preprocessor/repetition/enum_binary_params.hpp> |
| #include <boost/preprocessor/repetition/enum_trailing_params.hpp> |
| #include <boost/mpl/bool.hpp> |
| #include <boost/utility/enable_if.hpp> |
| #include <boost/utility/result_of.hpp> |
| #include <boost/proto/proto_fwd.hpp> |
| #include <boost/proto/args.hpp> |
| |
| namespace boost { namespace proto |
| { |
| |
| namespace detail |
| { |
| template<typename Expr> |
| struct by_value_generator_; |
| |
| template<typename Tag, typename Arg> |
| struct by_value_generator_<proto::expr<Tag, term<Arg>, 0> > |
| { |
| typedef |
| proto::expr< |
| Tag |
| , term<typename detail::term_traits<Arg>::value_type> |
| , 0 |
| > |
| type; |
| |
| static type const call(proto::expr<Tag, term<Arg>, 0> const &e) |
| { |
| type that = {e.child0}; |
| return that; |
| } |
| }; |
| |
| template<typename Tag, typename Arg> |
| struct by_value_generator_<proto::basic_expr<Tag, term<Arg>, 0> > |
| { |
| typedef |
| proto::basic_expr< |
| Tag |
| , term<typename detail::term_traits<Arg>::value_type> |
| , 0 |
| > |
| type; |
| |
| static type const call(proto::basic_expr<Tag, term<Arg>, 0> const &e) |
| { |
| type that = {e.child0}; |
| return that; |
| } |
| }; |
| |
| #define BOOST_PP_ITERATION_PARAMS_1 (3, (1, BOOST_PROTO_MAX_ARITY, <boost/proto/generate.hpp>)) |
| #include BOOST_PP_ITERATE() |
| |
| #undef BOOST_PROTO_DEFINE_BY_VALUE |
| #undef BOOST_PROTO_DEFINE_BY_VALUE_TYPE |
| |
| } |
| |
| /// \brief A simple generator that passes an expression |
| /// through unchanged. |
| /// |
| /// Generators are intended for use as the first template parameter |
| /// to the \c domain\<\> class template and control if and how |
| /// expressions within that domain are to be customized. |
| /// The \c default_generator makes no modifications to the expressions |
| /// passed to it. |
| struct default_generator |
| { |
| BOOST_PROTO_CALLABLE() |
| |
| template<typename Sig> |
| struct result; |
| |
| template<typename This, typename Expr> |
| struct result<This(Expr)> |
| { |
| typedef Expr type; |
| }; |
| |
| /// \param expr A Proto expression |
| /// \return expr |
| template<typename Expr> |
| #ifdef BOOST_PROTO_STRICT_RESULT_OF |
| Expr |
| #else |
| Expr const & |
| #endif |
| operator ()(Expr const &e) const |
| { |
| return e; |
| } |
| }; |
| |
| /// \brief A generator that wraps expressions passed |
| /// to it in the specified extension wrapper. |
| /// |
| /// Generators are intended for use as the first template parameter |
| /// to the \c domain\<\> class template and control if and how |
| /// expressions within that domain are to be customized. |
| /// \c generator\<\> wraps each expression passed to it in |
| /// the \c Extends\<\> wrapper. |
| template<template<typename> class Extends> |
| struct generator |
| { |
| BOOST_PROTO_CALLABLE() |
| BOOST_PROTO_USE_BASIC_EXPR() |
| |
| template<typename Sig> |
| struct result; |
| |
| template<typename This, typename Expr> |
| struct result<This(Expr)> |
| { |
| typedef Extends<Expr> type; |
| }; |
| |
| template<typename This, typename Expr> |
| struct result<This(Expr &)> |
| { |
| typedef Extends<Expr> type; |
| }; |
| |
| template<typename This, typename Expr> |
| struct result<This(Expr const &)> |
| { |
| typedef Extends<Expr> type; |
| }; |
| |
| /// \param expr A Proto expression |
| /// \return Extends<Expr>(expr) |
| template<typename Expr> |
| Extends<Expr> operator ()(Expr const &e) const |
| { |
| return Extends<Expr>(e); |
| } |
| }; |
| |
| /// \brief A generator that wraps expressions passed |
| /// to it in the specified extension wrapper and uses |
| /// aggregate initialization for the wrapper. |
| /// |
| /// Generators are intended for use as the first template parameter |
| /// to the \c domain\<\> class template and control if and how |
| /// expressions within that domain are to be customized. |
| /// \c pod_generator\<\> wraps each expression passed to it in |
| /// the \c Extends\<\> wrapper, and uses aggregate initialzation |
| /// for the wrapped object. |
| template<template<typename> class Extends> |
| struct pod_generator |
| { |
| BOOST_PROTO_CALLABLE() |
| BOOST_PROTO_USE_BASIC_EXPR() |
| |
| template<typename Sig> |
| struct result; |
| |
| template<typename This, typename Expr> |
| struct result<This(Expr)> |
| { |
| typedef Extends<Expr> type; |
| }; |
| |
| template<typename This, typename Expr> |
| struct result<This(Expr &)> |
| { |
| typedef Extends<Expr> type; |
| }; |
| |
| template<typename This, typename Expr> |
| struct result<This(Expr const &)> |
| { |
| typedef Extends<Expr> type; |
| }; |
| |
| /// \param expr The expression to wrap |
| /// \return <tt>Extends\<Expr\> that = {expr}; return that;</tt> |
| template<typename Expr> |
| Extends<Expr> operator ()(Expr const &e) const |
| { |
| Extends<Expr> that = {e}; |
| return that; |
| } |
| }; |
| |
| /// \brief A generator that replaces child nodes held by |
| /// reference with ones held by value. Use with |
| /// \c compose_generators to forward that result to another |
| /// generator. |
| /// |
| /// Generators are intended for use as the first template parameter |
| /// to the \c domain\<\> class template and control if and how |
| /// expressions within that domain are to be customized. |
| /// \c by_value_generator ensures all child nodes are |
| /// held by value. This generator is typically composed with a |
| /// second generator for further processing, as |
| /// <tt>compose_generators\<by_value_generator, MyGenerator\></tt>. |
| struct by_value_generator |
| { |
| BOOST_PROTO_CALLABLE() |
| |
| template<typename Sig> |
| struct result; |
| |
| template<typename This, typename Expr> |
| struct result<This(Expr)> |
| { |
| typedef |
| typename detail::by_value_generator_<Expr>::type |
| type; |
| }; |
| |
| template<typename This, typename Expr> |
| struct result<This(Expr &)> |
| { |
| typedef |
| typename detail::by_value_generator_<Expr>::type |
| type; |
| }; |
| |
| template<typename This, typename Expr> |
| struct result<This(Expr const &)> |
| { |
| typedef |
| typename detail::by_value_generator_<Expr>::type |
| type; |
| }; |
| |
| /// \param expr The expression to modify. |
| /// \return <tt>deep_copy(expr)</tt> |
| template<typename Expr> |
| typename result<by_value_generator(Expr)>::type operator ()(Expr const &e) const |
| { |
| return detail::by_value_generator_<Expr>::call(e); |
| } |
| }; |
| |
| /// \brief A composite generator that first applies one |
| /// transform to an expression and then forwards the result |
| /// on to another generator for further transformation. |
| /// |
| /// Generators are intended for use as the first template parameter |
| /// to the \c domain\<\> class template and control if and how |
| /// expressions within that domain are to be customized. |
| /// \c compose_generators\<\> is a composite generator that first |
| /// applies one transform to an expression and then forwards the |
| /// result on to another generator for further transformation. |
| template<typename First, typename Second> |
| struct compose_generators |
| { |
| BOOST_PROTO_CALLABLE() |
| |
| template<typename Sig> |
| struct result; |
| |
| template<typename This, typename Expr> |
| struct result<This(Expr)> |
| { |
| typedef |
| typename Second::template result< |
| Second(typename First::template result<First(Expr)>::type) |
| >::type |
| type; |
| }; |
| |
| template<typename This, typename Expr> |
| struct result<This(Expr &)> |
| { |
| typedef |
| typename Second::template result< |
| Second(typename First::template result<First(Expr)>::type) |
| >::type |
| type; |
| }; |
| |
| template<typename This, typename Expr> |
| struct result<This(Expr const &)> |
| { |
| typedef |
| typename Second::template result< |
| Second(typename First::template result<First(Expr)>::type) |
| >::type |
| type; |
| }; |
| |
| /// \param expr The expression to modify. |
| /// \return Second()(First()(expr)) |
| template<typename Expr> |
| typename result<compose_generators(Expr)>::type operator ()(Expr const &e) const |
| { |
| return Second()(First()(e)); |
| } |
| }; |
| |
| /// \brief Annotate a generator to indicate that it would |
| /// prefer to be passed instances of \c proto::basic_expr\<\> rather |
| /// than \c proto::expr\<\>. <tt>use_basic_expr\<Generator\></tt> is |
| /// itself a generator. |
| /// |
| template<typename Generator> |
| struct use_basic_expr |
| : Generator |
| { |
| BOOST_PROTO_USE_BASIC_EXPR() |
| }; |
| |
| /// \brief Tests a generator to see whether it would prefer |
| /// to be passed instances of \c proto::basic_expr\<\> rather than |
| /// \c proto::expr\<\>. |
| /// |
| template<typename Generator, typename Void> |
| struct wants_basic_expr |
| : mpl::false_ |
| {}; |
| |
| template<typename Generator> |
| struct wants_basic_expr<Generator, typename Generator::proto_use_basic_expr_> |
| : mpl::true_ |
| {}; |
| |
| /// INTERNAL ONLY |
| template<> |
| struct is_callable<default_generator> |
| : mpl::true_ |
| {}; |
| |
| /// INTERNAL ONLY |
| template<template<typename> class Extends> |
| struct is_callable<generator<Extends> > |
| : mpl::true_ |
| {}; |
| |
| /// INTERNAL ONLY |
| template<template<typename> class Extends> |
| struct is_callable<pod_generator<Extends> > |
| : mpl::true_ |
| {}; |
| |
| /// INTERNAL ONLY |
| template<> |
| struct is_callable<by_value_generator> |
| : mpl::true_ |
| {}; |
| |
| /// INTERNAL ONLY |
| template<typename First, typename Second> |
| struct is_callable<compose_generators<First, Second> > |
| : mpl::true_ |
| {}; |
| |
| }} |
| |
| // Specialization of boost::result_of to eliminate some unnecessary template instantiations |
| namespace boost |
| { |
| template<typename Expr> |
| struct result_of<proto::default_domain(Expr)> |
| { |
| typedef Expr type; |
| }; |
| |
| template<typename Expr> |
| struct result_of<proto::default_generator(Expr)> |
| { |
| typedef Expr type; |
| }; |
| } |
| |
| #endif // BOOST_PROTO_GENERATE_HPP_EAN_02_13_2007 |
| |
| #else // BOOST_PP_IS_ITERATING |
| |
| #define N BOOST_PP_ITERATION() |
| |
| template<typename Tag BOOST_PP_ENUM_TRAILING_PARAMS(N, typename Arg) > |
| struct by_value_generator_< |
| proto::expr<Tag, BOOST_PP_CAT(list, N)<BOOST_PP_ENUM_PARAMS(N, Arg)>, N> |
| > |
| { |
| typedef |
| BOOST_PP_CAT(list, N)<BOOST_PP_ENUM_PARAMS(N, Arg)> |
| src_args; |
| |
| typedef |
| BOOST_PP_CAT(list, N)< |
| BOOST_PP_ENUM_BINARY_PARAMS(N, typename uncvref<Arg, >::type BOOST_PP_INTERCEPT) |
| > |
| dst_args; |
| |
| typedef proto::expr<Tag, src_args, N> src_type; |
| typedef proto::expr<Tag, dst_args, N> type; |
| |
| static type const call(src_type const &e) |
| { |
| type that = { |
| BOOST_PP_ENUM_PARAMS(N, e.child) |
| }; |
| return that; |
| } |
| }; |
| |
| template<typename Tag BOOST_PP_ENUM_TRAILING_PARAMS(N, typename Arg) > |
| struct by_value_generator_< |
| proto::basic_expr<Tag, BOOST_PP_CAT(list, N)<BOOST_PP_ENUM_PARAMS(N, Arg)>, N> |
| > |
| { |
| typedef |
| BOOST_PP_CAT(list, N)<BOOST_PP_ENUM_PARAMS(N, Arg)> |
| src_args; |
| |
| typedef |
| BOOST_PP_CAT(list, N)< |
| BOOST_PP_ENUM_BINARY_PARAMS(N, typename uncvref<Arg, >::type BOOST_PP_INTERCEPT) |
| > |
| dst_args; |
| |
| typedef proto::basic_expr<Tag, src_args, N> src_type; |
| typedef proto::basic_expr<Tag, dst_args, N> type; |
| |
| static type const call(src_type const &e) |
| { |
| type that = { |
| BOOST_PP_ENUM_PARAMS(N, e.child) |
| }; |
| return that; |
| } |
| }; |
| |
| #undef N |
| |
| #endif |