378 lines
12 KiB
C++
378 lines
12 KiB
C++
#ifndef BOOST_PP_IS_ITERATING
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///////////////////////////////////////////////////////////////////////////////
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/// \file generate.hpp
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/// Contains definition of generate\<\> class template, which end users can
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/// specialize for generating domain-specific expression wrappers.
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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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#ifndef BOOST_PROTO_GENERATE_HPP_EAN_02_13_2007
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#define BOOST_PROTO_GENERATE_HPP_EAN_02_13_2007
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#include <boost/proto/detail/prefix.hpp>
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#include <boost/config.hpp>
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#include <boost/utility/result_of.hpp>
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#include <boost/preprocessor/cat.hpp>
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#include <boost/preprocessor/iteration/iterate.hpp>
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#include <boost/preprocessor/repetition/enum.hpp>
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#include <boost/utility/enable_if.hpp>
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#include <boost/proto/proto_fwd.hpp>
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#include <boost/proto/args.hpp>
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#include <boost/proto/detail/suffix.hpp>
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namespace boost { namespace proto
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{
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namespace detail
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{
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template<typename Expr>
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struct expr_params;
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template<typename Tag, typename Args, long N>
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struct expr_params<proto::expr<Tag, Args, N> >
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{
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typedef Tag tag;
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typedef Args args;
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BOOST_STATIC_CONSTANT(long, arity = N);
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};
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template<typename Expr, long Arity = expr_params<Expr>::arity>
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struct by_value_generator_;
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#define BOOST_PROTO_DEFINE_BY_VALUE_TYPE(Z, N, Expr) \
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typename uncvref<typename expr_params<Expr>::args::BOOST_PP_CAT(child, N)>::type \
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/**/
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#define BOOST_PROTO_DEFINE_BY_VALUE(Z, N, expr) \
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expr.BOOST_PP_CAT(child, N) \
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/**/
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template<typename Expr>
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struct by_value_generator_<Expr, 0>
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{
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typedef
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proto::expr<
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typename expr_params<Expr>::tag
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, term<typename detail::term_traits<typename expr_params<Expr>::args::child0>::value_type>
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>
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type;
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static type const make(Expr const &expr)
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{
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type that = {expr.child0};
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return that;
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}
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};
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#define BOOST_PP_ITERATION_PARAMS_1 (3, (1, BOOST_PROTO_MAX_ARITY, <boost/proto/generate.hpp>))
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#include BOOST_PP_ITERATE()
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#undef BOOST_PROTO_DEFINE_BY_VALUE
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#undef BOOST_PROTO_DEFINE_BY_VALUE_TYPE
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}
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BOOST_PROTO_BEGIN_ADL_NAMESPACE(generatorns_)
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/// \brief A simple generator that passes an expression
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/// through unchanged.
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///
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/// Generators are intended for use as the first template parameter
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/// to the \c domain\<\> class template and control if and how
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/// expressions within that domain are to be customized.
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/// The \c default_generator makes no modifications to the expressions
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/// passed to it.
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struct default_generator
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{
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BOOST_PROTO_CALLABLE()
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template<typename Sig>
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struct result;
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template<typename This, typename Expr>
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struct result<This(Expr)>
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{
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typedef Expr type;
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};
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/// \param expr A Proto expression
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/// \return expr
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template<typename Expr>
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#ifdef BOOST_HAS_DECLTYPE
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Expr
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#else
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Expr const &
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#endif
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operator ()(Expr const &expr) const
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{
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return expr;
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}
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};
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/// \brief A generator that wraps expressions passed
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/// to it in the specified extension wrapper.
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///
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/// Generators are intended for use as the first template parameter
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/// to the \c domain\<\> class template and control if and how
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/// expressions within that domain are to be customized.
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/// \c generator\<\> wraps each expression passed to it in
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/// the \c Extends\<\> wrapper.
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template<template<typename> class Extends>
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struct generator
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{
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BOOST_PROTO_CALLABLE()
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template<typename Sig>
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struct result;
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template<typename This, typename Expr>
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struct result<This(Expr)>
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{
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typedef Extends<Expr> type;
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};
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template<typename This, typename Expr>
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struct result<This(Expr &)>
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{
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typedef Extends<Expr> type;
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};
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template<typename This, typename Expr>
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struct result<This(Expr const &)>
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{
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typedef Extends<Expr> type;
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};
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/// \param expr A Proto expression
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/// \return Extends<Expr>(expr)
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template<typename Expr>
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Extends<Expr> operator ()(Expr const &expr) const
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{
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return Extends<Expr>(expr);
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}
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};
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/// \brief A generator that wraps expressions passed
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/// to it in the specified extension wrapper and uses
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/// aggregate initialization for the wrapper.
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///
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/// Generators are intended for use as the first template parameter
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/// to the \c domain\<\> class template and control if and how
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/// expressions within that domain are to be customized.
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/// \c pod_generator\<\> wraps each expression passed to it in
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/// the \c Extends\<\> wrapper, and uses aggregate initialzation
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/// for the wrapped object.
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template<template<typename> class Extends>
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struct pod_generator
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{
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BOOST_PROTO_CALLABLE()
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template<typename Sig>
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struct result;
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template<typename This, typename Expr>
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struct result<This(Expr)>
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{
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typedef Extends<Expr> type;
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};
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template<typename This, typename Expr>
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struct result<This(Expr &)>
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{
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typedef Extends<Expr> type;
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};
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template<typename This, typename Expr>
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struct result<This(Expr const &)>
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{
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typedef Extends<Expr> type;
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};
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/// \param expr The expression to wrap
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/// \return <tt>Extends\<Expr\> that = {expr}; return that;</tt>
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template<typename Expr>
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Extends<Expr> operator ()(Expr const &expr) const
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{
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Extends<Expr> that = {expr};
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return that;
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}
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};
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/// \brief A generator that replaces child nodes held by
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/// reference with ones held by value. Use with
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/// \c compose_generators to forward that result to another
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/// generator.
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///
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/// Generators are intended for use as the first template parameter
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/// to the \c domain\<\> class template and control if and how
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/// expressions within that domain are to be customized.
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/// \c by_value_generator ensures all child nodes are
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/// held by value. This generator is typically composed with a
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/// second generator for further processing, as
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/// <tt>compose_generators\<by_value_generator, MyGenerator\></tt>.
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struct by_value_generator
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{
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BOOST_PROTO_CALLABLE()
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template<typename Sig>
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struct result;
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template<typename This, typename Expr>
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struct result<This(Expr)>
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{
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typedef
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typename detail::by_value_generator_<Expr>::type
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type;
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};
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template<typename This, typename Expr>
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struct result<This(Expr &)>
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{
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typedef
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typename detail::by_value_generator_<Expr>::type
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type;
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};
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template<typename This, typename Expr>
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struct result<This(Expr const &)>
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{
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typedef
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typename detail::by_value_generator_<Expr>::type
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type;
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};
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/// \param expr The expression to modify.
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/// \return <tt>deep_copy(expr)</tt>
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template<typename Expr>
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typename result<void(Expr)>::type operator ()(Expr const &expr) const
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{
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return detail::by_value_generator_<Expr>::make(expr);
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}
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};
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/// \brief A composite generator that first applies one
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/// transform to an expression and then forwards the result
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/// on to another generator for further transformation.
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///
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/// Generators are intended for use as the first template parameter
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/// to the \c domain\<\> class template and control if and how
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/// expressions within that domain are to be customized.
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/// \c compose_generators\<\> is a composite generator that first
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/// applies one transform to an expression and then forwards the
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/// result on to another generator for further transformation.
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template<typename First, typename Second>
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struct compose_generators
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{
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BOOST_PROTO_CALLABLE()
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template<typename Sig>
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struct result;
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template<typename This, typename Expr>
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struct result<This(Expr)>
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{
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typedef
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typename Second::template result<
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void(typename First::template result<void(Expr)>::type)
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>::type
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type;
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};
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template<typename This, typename Expr>
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struct result<This(Expr &)>
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{
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typedef
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typename Second::template result<
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void(typename First::template result<void(Expr)>::type)
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>::type
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type;
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};
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template<typename This, typename Expr>
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struct result<This(Expr const &)>
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{
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typedef
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typename Second::template result<
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void(typename First::template result<void(Expr)>::type)
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>::type
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type;
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};
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/// \param expr The expression to modify.
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/// \return Second()(First()(expr))
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template<typename Expr>
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typename result<void(Expr)>::type operator ()(Expr const &expr) const
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{
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return Second()(First()(expr));
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}
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};
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BOOST_PROTO_END_ADL_NAMESPACE(generatorns_)
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/// INTERNAL ONLY
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template<>
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struct is_callable<default_generator>
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: mpl::true_
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{};
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/// INTERNAL ONLY
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template<template<typename> class Extends>
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struct is_callable<generator<Extends> >
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: mpl::true_
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{};
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/// INTERNAL ONLY
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template<template<typename> class Extends>
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struct is_callable<pod_generator<Extends> >
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: mpl::true_
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{};
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/// INTERNAL ONLY
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template<>
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struct is_callable<by_value_generator>
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: mpl::true_
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{};
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/// INTERNAL ONLY
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template<typename First, typename Second>
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struct is_callable<compose_generators<First, Second> >
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: mpl::true_
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{};
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}}
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#endif // BOOST_PROTO_GENERATE_HPP_EAN_02_13_2007
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#else // BOOST_PP_IS_ITERATING
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#define N BOOST_PP_ITERATION()
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template<typename Expr>
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struct by_value_generator_<Expr, N>
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{
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typedef
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proto::expr<
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typename expr_params<Expr>::tag
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, BOOST_PP_CAT(list, N)<
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// typename uncvref<typename expr_params<Expr>::args::child0>::type, ...
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BOOST_PP_ENUM(N, BOOST_PROTO_DEFINE_BY_VALUE_TYPE, Expr)
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>
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>
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type;
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static type const make(Expr const &expr)
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{
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type that = {
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// expr.child0, ...
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BOOST_PP_ENUM(N, BOOST_PROTO_DEFINE_BY_VALUE, expr)
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};
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return that;
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}
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};
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#undef N
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#endif
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