You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
216 lines
7.2 KiB
216 lines
7.2 KiB
5 years ago
|
/// @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
|