/////////////////////////////////////////////////////////////////////////////// /// \file literal.hpp /// The literal\<\> terminal wrapper, and the proto::lit() function for /// creating literal\<\> 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_LITERAL_HPP_EAN_01_03_2007 #define BOOST_PROTO_LITERAL_HPP_EAN_01_03_2007 #include <boost/config.hpp> #include <boost/proto/proto_fwd.hpp> #include <boost/proto/expr.hpp> #include <boost/proto/traits.hpp> #include <boost/proto/extends.hpp> namespace boost { namespace proto { namespace utility { /// \brief A simple wrapper for a terminal, provided for /// ease of use. /// /// A simple wrapper for a terminal, provided for /// ease of use. In all cases, <tt>literal\<X\> l(x);</tt> /// is equivalent to <tt>terminal\<X\>::type l = {x};</tt>. /// /// The \c Domain template parameter defaults to /// \c proto::default_domain. template< typename T , typename Domain // = default_domain > struct literal : extends<basic_expr<tag::terminal, term<T>, 0>, literal<T, Domain>, Domain> { private: typedef basic_expr<tag::terminal, term<T>, 0> terminal_type; typedef extends<terminal_type, literal<T, Domain>, Domain> base_type; typedef literal<T, Domain> literal_t; public: typedef typename detail::term_traits<T>::value_type value_type; typedef typename detail::term_traits<T>::reference reference; typedef typename detail::term_traits<T>::const_reference const_reference; literal() : base_type(terminal_type::make(T())) {} template<typename U> literal(U &u) : base_type(terminal_type::make(u)) {} template<typename U> literal(U const &u) : base_type(terminal_type::make(u)) {} template<typename U> literal(literal<U, Domain> const &u) : base_type(terminal_type::make(u.get())) {} BOOST_PROTO_EXTENDS_USING_ASSIGN(literal_t) reference get() { return proto::value(*this); } const_reference get() const { return proto::value(*this); } }; } /// \brief A helper function for creating a \c literal\<\> wrapper. /// \param t The object to wrap. /// \return literal\<T &\>(t) /// \attention The returned value holds the argument by reference. /// \throw nothrow template<typename T> inline literal<T &> const lit(T &t) { return literal<T &>(t); } /// \overload /// template<typename T> inline literal<T const &> const lit(T const &t) { #ifdef BOOST_MSVC #pragma warning(push) #pragma warning(disable: 4180) // warning C4180: qualifier applied to function type has no meaning; ignored #endif return literal<T const &>(t); #ifdef BOOST_MSVC #pragma warning(pop) #endif } }} #endif