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suyu/externals/vcpkg/packages/boost-proto_x64-windows/include/boost/proto/eval.hpp
2024-03-05 16:42:40 +08:00

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///////////////////////////////////////////////////////////////////////////////
/// \file eval.hpp
/// Contains the eval() expression evaluator.
//
// 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_EVAL_HPP_EAN_03_29_2007
#define BOOST_PROTO_EVAL_HPP_EAN_03_29_2007
#include <boost/proto/proto_fwd.hpp> // BOOST_PROTO_CALLABLE
#include <boost/type_traits/remove_reference.hpp>
namespace boost { namespace proto
{
namespace result_of
{
/// \brief A metafunction for calculating the return type
/// of \c proto::eval() given a certain \c Expr and \c Context
/// types.
///
/// \note The types \c Expr and \c Context should not be
/// reference types. They may be cv-qualified, but the
/// cv-qualification on the \c Context parameter is ignored.
template<typename Expr, typename Context>
struct eval
{
typedef typename Context::template eval<Expr>::result_type type;
};
}
namespace functional
{
/// \brief A PolymorphicFunctionObject type for
/// evaluating a given Proto expression with a given
/// context.
struct eval
{
BOOST_PROTO_CALLABLE()
template<typename Sig>
struct result;
template<typename This, typename Expr, typename Context>
struct result<This(Expr, Context)>
{
typedef
typename proto::result_of::eval<
typename remove_reference<Expr>::type
, typename remove_reference<Context>::type
>::type
type;
};
/// \brief Evaluate a given Proto expression with a given
/// context.
/// \param expr The Proto expression to evaluate
/// \param context The context in which the expression should be
/// evaluated.
/// \return <tt>typename Context::template eval<Expr>()(expr, context)</tt>
template<typename Expr, typename Context>
typename proto::result_of::eval<Expr, Context>::type
operator ()(Expr &e, Context &ctx) const
{
return typename Context::template eval<Expr>()(e, ctx);
}
/// \overload
///
template<typename Expr, typename Context>
typename proto::result_of::eval<Expr, Context>::type
operator ()(Expr &e, Context const &ctx) const
{
return typename Context::template eval<Expr>()(e, ctx);
}
/// \overload
///
template<typename Expr, typename Context>
typename proto::result_of::eval<Expr const, Context>::type
operator ()(Expr const &e, Context &ctx) const
{
return typename Context::template eval<Expr const>()(e, ctx);
}
/// \overload
///
template<typename Expr, typename Context>
typename proto::result_of::eval<Expr const, Context>::type
operator ()(Expr const &e, Context const &ctx) const
{
return typename Context::template eval<Expr const>()(e, ctx);
}
};
}
/// \brief Evaluate a given Proto expression with a given
/// context.
/// \param expr The Proto expression to evaluate
/// \param context The context in which the expression should be
/// evaluated.
/// \return <tt>typename Context::template eval<Expr>()(expr, context)</tt>
template<typename Expr, typename Context>
typename proto::result_of::eval<Expr, Context>::type
eval(Expr &e, Context &ctx)
{
return typename Context::template eval<Expr>()(e, ctx);
}
/// \overload
///
template<typename Expr, typename Context>
typename proto::result_of::eval<Expr, Context>::type
eval(Expr &e, Context const &ctx)
{
return typename Context::template eval<Expr>()(e, ctx);
}
/// \overload
///
template<typename Expr, typename Context>
typename proto::result_of::eval<Expr const, Context>::type
eval(Expr const &e, Context &ctx)
{
return typename Context::template eval<Expr const>()(e, ctx);
}
/// \overload
///
template<typename Expr, typename Context>
typename proto::result_of::eval<Expr const, Context>::type
eval(Expr const &e, Context const &ctx)
{
return typename Context::template eval<Expr const>()(e, ctx);
}
}}
#endif