Sprout/sprout/utility/value_holder/io.hpp

/*=============================================================================
  Copyright (c) 2011-2016 Bolero MURAKAMI
  https://github.com/bolero-MURAKAMI/Sprout

  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 SPROUT_UTILITY_VALUE_HOLDER_IO_HPP
#define SPROUT_UTILITY_VALUE_HOLDER_IO_HPP

#include <istream>
#include <ostream>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/utility/value_holder/value_holder.hpp>

namespace sprout {
	//
	// operator>>
	//
	template<typename Elem, typename Traits, typename T>
	inline SPROUT_NON_CONSTEXPR typename std::enable_if<
		!std::is_reference<T>::value,
		std::basic_istream<Elem, Traits>&
	>::type
	operator>>(std::basic_istream<Elem, Traits>& lhs, sprout::value_holder<T>& rhs) {
		if (lhs.good()) {
			int d = lhs.get();
			if (d == ' ') {
				T x;
				lhs >> x;
				rhs = x;
			} else {
				lhs.setstate(std::ios::failbit);
			}
		}
		return lhs;
	}
	//
	// operator<<
	//
	template<typename Elem, typename Traits, typename T>
	inline SPROUT_NON_CONSTEXPR std::basic_ostream<Elem, Traits>&
	operator<<(std::basic_ostream<Elem, Traits>& lhs, sprout::value_holder<T> const& rhs) {
		if (lhs.good()) {
			if (!rhs) {
				lhs << "--";
			} else {
				lhs << ' ' << *rhs;
			}
		}
		return lhs;
	}
}	// namespace sprout

#endif	// #ifndef SPROUT_UTILITY_VALUE_HOLDER_IO_HPP