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