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///////////////////////////////////////////////////////////////////////////////
/// \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
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