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- /// @file
- // Boost.Convert
- // Copyright (c) 2009-2016 Vladimir Batov.
- //
- // Many thanks to Julian Gonggrijp, Rob Stewart, Andrzej Krzemienski, Matus Chochlik, Jeroen Habraken,
- // Hartmut Kaiser, Joel De Guzman, Thijs (M.A.) van den Berg, Roland Bock, Gavin Lambert, Paul Bristow,
- // Alex Hagen-Zanker, Christopher Kormanyos for taking part in the Boost.Convert review.
- //
- // Special thanks to:
- //
- // 1. Alex Hagen-Zanker, Roland Bock, Rob Stewart for their considerable contributions to the design
- // and implementation of the library;
- // 2. Andrzej Krzemienski for helping to partition responsibilities and to ultimately pave
- // the way for the boost::optional and future std::tr2::optional deployment;
- // 3. Edward Diener the Boost Review Manager for helping with the converters' design, his continuous
- // involvement, technical and administrative help, guidance and advice;
- // 4. Joel De Guzman, Rob Stewart and Alex Hagen-Zanker for making sure the performance tests work
- // as they should;
- // 5. Paul Bristow for helping great deal with the documentation;
- // 6. Kevlin Henney and Dave Abrahams for their lexical_cast-related insights and explanations.
- //
- // Use, modification and distribution are subject to the Boost Software License,
- // Version 1.0. See http://www.boost.org/LICENSE_1_0.txt.
- #ifndef BOOST_CONVERT_HPP
- #define BOOST_CONVERT_HPP
- #include <boost/convert/detail/is_fun.hpp>
- #include <boost/ref.hpp>
- namespace boost
- {
- namespace detail { enum throw_on_failure {}; }
- /// @details boost::throw_on_failure is the 'tag' object
- /// to request the exception-throwing behavior.
- detail::throw_on_failure const throw_on_failure = detail::throw_on_failure(0);
- namespace cnv
- {
- template<typename, typename, typename> struct reference;
- struct by_default;
- }
- /// @brief Boost.Convert main deployment interface
- /// @param[in] value_in Value of the TypeIn type to be converted to the TypeOut type
- /// @param[in] converter Converter to be used for conversion
- /// @return boost::optional<TypeOut> result of conversion together with the indication of
- /// success or failure of the conversion request.
- /// @details For example,
- /// @code
- /// boost::cnv::cstream cnv;
- ///
- /// boost::optional<int> i = boost::convert<int>("12", cnv);
- /// boost::optional<string> s = boost::convert<string>(123.456, cnv);
- /// @endcode
- template<typename TypeOut, typename TypeIn, typename Converter>
- boost::optional<TypeOut>
- convert(TypeIn const& value_in, Converter const& converter)
- {
- optional<TypeOut> result;
- boost::unwrap_ref(converter)(value_in, result);
- return result;
- }
- namespace cnv { namespace detail
- {
- template<typename TypeOut, typename TypeIn, typename Converter =boost::cnv::by_default>
- struct delayed_resolution
- {
- static optional<TypeOut> convert(TypeIn const& value_in)
- {
- return boost::convert<TypeOut>(value_in, Converter());
- }
- };
- }}
- /// @brief Boost.Convert deployment interface with the default converter
- /// @details For example,
- /// @code
- /// struct boost::cnv::by_default : boost::cnv::cstream {};
- ///
- /// // boost::cnv::cstream (through boost::cnv::by_default) is deployed
- /// // as the default converter when no converter is provided explicitly.
- /// boost::optional<int> i = boost::convert<int>("12");
- /// boost::optional<string> s = boost::convert<string>(123.456);
- /// @endcode
- template<typename TypeOut, typename TypeIn>
- boost::optional<TypeOut>
- convert(TypeIn const& value_in)
- {
- return cnv::detail::delayed_resolution<TypeOut, TypeIn>::convert(value_in);
- }
- }
- namespace boost
- {
- /// @brief Boost.Convert non-optional deployment interface
- template<typename TypeOut, typename TypeIn, typename Converter>
- TypeOut
- convert(TypeIn const& value_in, Converter const& converter, boost::detail::throw_on_failure)
- {
- return convert<TypeOut>(value_in, converter).value();
- }
- template<typename TypeOut, typename TypeIn, typename Converter, typename Fallback>
- typename enable_if<is_convertible<Fallback, TypeOut>, TypeOut>::type
- convert(TypeIn const& value_in, Converter const& converter, Fallback const& fallback)
- {
- return convert<TypeOut>(value_in, converter).value_or(fallback);
- }
- template<typename TypeOut, typename TypeIn, typename Converter, typename Fallback>
- typename enable_if<cnv::is_fun<Fallback, TypeOut>, TypeOut>::type
- convert(TypeIn const& value_in, Converter const& converter, Fallback fallback)
- {
- return convert<TypeOut>(value_in, converter).value_or_eval(fallback);
- }
- }
- namespace boost { namespace cnv
- {
- template<typename Converter, typename TypeOut, typename TypeIn>
- struct reference
- {
- typedef reference this_type;
- reference(Converter const& cnv) : converter_(cnv) {}
- #ifdef BOOST_CONVERT_CXX11
- reference(Converter&& cnv) : converter_(std::move(cnv)) {}
- #endif
- this_type&
- value_or(TypeOut const& fallback)
- {
- return (fallback_ = fallback, *this);
- }
- TypeOut
- operator()(TypeIn const& value_in)
- {
- optional<TypeOut> result = convert<TypeOut>(value_in, converter_);
- return result ? result.get() : fallback_.value();
- }
- private:
- Converter converter_;
- optional<TypeOut> fallback_;
- };
- template<typename Converter, typename TypeOut>
- struct reference<Converter, TypeOut, void>
- {
- typedef reference this_type;
- reference(Converter const& cnv) : converter_(cnv) {}
- #ifdef BOOST_CONVERT_CXX11
- reference(Converter&& cnv) : converter_(std::move(cnv)) {}
- #endif
- this_type&
- value_or(TypeOut const& fallback)
- {
- return (fallback_ = fallback, *this);
- }
- template<typename TypeIn>
- TypeOut
- operator()(TypeIn const& value_in)
- {
- optional<TypeOut> result = convert<TypeOut>(value_in, converter_);
- return result ? result.get() : fallback_.value();
- }
- private:
- Converter converter_;
- optional<TypeOut> fallback_;
- };
- /// @brief Boost.Convert deployment interface with algorithms
- /// @details For example,
- /// @code
- /// boost::array<char const*, 3> strs = {{ " 5", "0XF", "not an int" }};
- /// std::vector<int> ints;
- /// boost::cnv::cstream cnv;
- ///
- /// cnv(std::hex)(std::skipws);
- ///
- /// std::transform(
- /// strs.begin(),
- /// strs.end(),
- /// std::back_inserter(ints),
- /// boost::cnv::apply<int>(boost::cref(cnv)).value_or(-1));
- /// @endcode
- template<typename TypeOut, typename TypeIn, typename Converter>
- reference<Converter, TypeOut, TypeIn>
- apply(Converter const& cnv)
- {
- return cnv::reference<Converter, TypeOut, TypeIn>(cnv);
- }
- template<typename TypeOut, typename Converter>
- reference<Converter, TypeOut, void>
- apply(Converter const& cnv)
- {
- return cnv::reference<Converter, TypeOut, void>(cnv);
- }
- }}
- #endif // BOOST_CONVERT_HPP
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