comparison DEPENDENCIES/generic/include/boost/proto/transform/arg.hpp @ 16:2665513ce2d3

Add boost headers

+///////////////////////////////////////////////////////////////////////////////
+/// \file arg.hpp
+/// Contains definition of the argN transforms.
+//
+//  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_ARG_HPP_EAN_11_01_2007
+#define BOOST_PROTO_TRANSFORM_ARG_HPP_EAN_11_01_2007
+
+#include <boost/mpl/if.hpp>
+#include <boost/proto/proto_fwd.hpp>
+#include <boost/proto/traits.hpp>
+#include <boost/proto/transform/impl.hpp>
+#include <boost/type_traits/is_array.hpp>
+#include <boost/proto/transform/env.hpp>
+
+namespace boost { namespace proto
+{
+
+    /// \brief A PrimitiveTransform that returns the current expression
+    /// unmodified
+    ///
+    /// Example:
+    ///
+    /// \code
+    /// proto::terminal<int>::type i = {42};
+    /// proto::terminal<int>::type & j = proto::_expr()(i);
+    /// assert( boost::addressof(i) == boost::addressof(j) );
+    /// \endcode
+    struct _expr : transform<_expr>
+    {
+        template<typename Expr, typename State, typename Data>
+        struct impl : transform_impl<Expr, State, Data>
+        {
+            typedef Expr result_type;
+
+            /// Returns the current expression.
+            /// \param e The current expression.
+            /// \return \c e
+            /// \throw nothrow
+            BOOST_PROTO_RETURN_TYPE_STRICT_LOOSE(result_type, typename impl::expr_param)
+            operator()(
+                typename impl::expr_param e
+              , typename impl::state_param
+              , typename impl::data_param
+            ) const
+            {
+                return e;
+            }
+        };
+    };
+
+    /// \brief A PrimitiveTransform that returns the current state
+    /// unmodified
+    ///
+    /// Example:
+    ///
+    /// \code
+    /// proto::terminal<int>::type i = {42};
+    /// char ch = proto::_state()(i, 'a');
+    /// assert( ch == 'a' );
+    /// \endcode
+    struct _state : transform<_state>
+    {
+        template<typename Expr, typename State, typename Data>
+        struct impl : transform_impl<Expr, State, Data>
+        {
+            typedef State result_type;
+
+            /// Returns the current state.
+            /// \param s The current state.
+            /// \return \c s
+            /// \throw nothrow
+            BOOST_PROTO_RETURN_TYPE_STRICT_LOOSE(result_type, typename impl::state_param)
+            operator ()(
+                typename impl::expr_param
+              , typename impl::state_param s
+              , typename impl::data_param
+            ) const
+            {
+                return s;
+            }
+        };
+    };
+
+    /// \brief A PrimitiveTransform that returns the current data
+    /// unmodified
+    ///
+    /// Example:
+    ///
+    /// \code
+    /// proto::terminal<int>::type i = {42};
+    /// std::string str("hello");
+    /// std::string & data = proto::_data()(i, 'a', str);
+    /// assert( &str == &data );
+    /// \endcode
+    struct _data : transform<_data>
+    {
+        template<typename Expr, typename State, typename Data>
+        struct impl
+          : mpl::if_c<
+                is_env<Data>::value
+              , _env_var<data_type>
+              , _env
+            >::type::template impl<Expr, State, Data>
+        {};
+    };
+
+    /// \brief A PrimitiveTransform that returns N-th child of the current
+    /// expression.
+    ///
+    /// Example:
+    ///
+    /// \code
+    /// proto::terminal<int>::type i = {42};
+    /// proto::terminal<int>::type & j = proto::_child_c<0>()(-i);
+    /// assert( boost::addressof(i) == boost::addressof(j) );
+    /// \endcode
+    template<int N>
+    struct _child_c : transform<_child_c<N> >
+    {
+        template<typename Expr, typename State, typename Data>
+        struct impl : transform_impl<Expr, State, Data>
+        {
+            typedef
+                typename result_of::child_c<Expr, N>::type
+            result_type;
+
+            /// Returns the N-th child of \c e
+            /// \pre <tt>arity_of\<Expr\>::value \> N</tt> 
+            /// \param e The current expression.
+            /// \return <tt>proto::child_c\<N\>(e)</tt>
+            /// \throw nothrow
+            #ifdef BOOST_PROTO_STRICT_RESULT_OF
+            result_type
+            #else
+            typename result_of::child_c<typename impl::expr_param, N>::type
+            #endif
+            operator ()(
+                typename impl::expr_param e
+              , typename impl::state_param
+              , typename impl::data_param
+            ) const
+            {
+                return proto::child_c<N>(e);
+            }
+        };
+    };
+
+    /// \brief A PrimitiveTransform that returns the value of the
+    /// current terminal expression.
+    ///
+    /// Example:
+    ///
+    /// \code
+    /// proto::terminal<int>::type i = {42};
+    /// int j = proto::_value()(i);
+    /// assert( 42 == j );
+    /// \endcode
+    struct _value : transform<_value>
+    {
+        template<typename Expr, typename State, typename Data>
+        struct impl : transform_impl<Expr, State, Data>
+        {
+            typedef
+                typename result_of::value<Expr>::type
+            result_type;
+
+            /// Returns the value of the specified terminal expression.
+            /// \pre <tt>arity_of\<Expr\>::value == 0</tt>.
+            /// \param e The current expression.
+            /// \return <tt>proto::value(e)</tt>
+            /// \throw nothrow
+            #ifdef BOOST_PROTO_STRICT_RESULT_OF
+            typename mpl::if_c<is_array<result_type>::value, result_type &, result_type>::type
+            #else
+            typename result_of::value<typename impl::expr_param>::type
+            #endif
+            operator ()(
+                typename impl::expr_param e
+              , typename impl::state_param
+              , typename impl::data_param
+            ) const
+            {
+                return proto::value(e);
+            }
+        };
+    };
+
+    /// \brief A PrimitiveTransform that does nothing
+    /// and returns void.
+    struct _void : transform<_void>
+    {
+        template<typename Expr, typename State, typename Data>
+        struct impl : transform_impl<Expr, State, Data>
+        {
+            typedef void result_type;
+
+            /// Does nothing and returns void
+            void operator ()(
+                typename impl::expr_param
+              , typename impl::state_param
+              , typename impl::data_param
+            ) const
+            {}
+        };
+    };
+
+    /// \brief A unary CallableTransform that wraps its argument
+    /// in a \c boost::reference_wrapper\<\>.
+    ///
+    /// Example:
+    ///
+    /// \code
+    /// proto::terminal<int>::type i = {42};
+    /// boost::reference_wrapper<proto::terminal<int>::type> j
+    ///     = proto::when<_, proto::_byref(_)>()(i);
+    /// assert( boost::addressof(i) == boost::addressof(j.get()) );
+    /// \endcode
+    struct _byref : callable
+    {
+        template<typename Sig>
+        struct result;
+
+        template<typename This, typename T>
+        struct result<This(T)>
+        {
+            typedef boost::reference_wrapper<T const> const type;
+        };
+
+        template<typename This, typename T>
+        struct result<This(T &)>
+        {
+            typedef boost::reference_wrapper<T> const type;
+        };
+
+        /// Wrap the parameter \c t in a \c boost::reference_wrapper\<\>
+        /// \param t The object to wrap
+        /// \return <tt>boost::ref(t)</tt>
+        /// \throw nothrow
+        template<typename T>
+        boost::reference_wrapper<T> const operator ()(T &t) const
+        {
+            return boost::reference_wrapper<T>(t);
+        }
+
+        /// \overload
+        ///
+        template<typename T>
+        boost::reference_wrapper<T const> const operator ()(T const &t) const
+        {
+            return boost::reference_wrapper<T const>(t);
+        }
+    };
+
+    /// \brief A unary CallableTransform that strips references
+    /// and \c boost::reference_wrapper\<\> from its argument.
+    ///
+    /// Example:
+    ///
+    /// \code
+    /// proto::terminal<int>::type i = {42};
+    /// int j = 67;
+    /// int k = proto::when<_, proto::_byval(proto::_state)>()(i, boost::ref(j));
+    /// assert( 67 == k );
+    /// \endcode
+    struct _byval : callable
+    {
+        template<typename Sig>
+        struct result;
+
+        template<typename This, typename T>
+        struct result<This(T)>
+        {
+            typedef T type;
+        };
+
+        template<typename This, typename T>
+        struct result<This(T &)>
+          : result<This(T)>
+        {};
+
+        template<typename This, typename T>
+        struct result<This(boost::reference_wrapper<T>)>
+          : result<This(T)>
+        {};
+
+        /// \param t The object to unref
+        /// \return <tt>t</tt>
+        /// \throw nothrow
+        template<typename T>
+        T operator ()(T const &t) const
+        {
+            return t;
+        }
+
+        /// \overload
+        ///
+        template<typename T>
+        T operator ()(boost::reference_wrapper<T> const &t) const
+        {
+            return t;
+        }
+    };
+
+    /// INTERNAL ONLY
+    ///
+    template<>
+    struct is_callable<_expr>
+      : mpl::true_
+    {};
+
+    /// INTERNAL ONLY
+    ///
+    template<>
+    struct is_callable<_state>
+      : mpl::true_
+    {};
+
+    /// INTERNAL ONLY
+    ///
+    template<>
+    struct is_callable<_data>
+      : mpl::true_
+    {};
+
+    /// INTERNAL ONLY
+    ///
+    template<int N>
+    struct is_callable<_child_c<N> >
+      : mpl::true_
+    {};
+
+    /// INTERNAL ONLY
+    ///
+    template<>
+    struct is_callable<_value>
+      : mpl::true_
+    {};
+
+    /// INTERNAL ONLY
+    ///
+    template<>
+    struct is_callable<_byref>
+      : mpl::true_
+    {};
+
+    /// INTERNAL ONLY
+    ///
+    template<>
+    struct is_callable<_byval>
+      : mpl::true_
+    {};
+
+}}
+
+#endif