ext-boost/boost/lexical_cast/detail/converter_lexical.hpp
2019-08-24 15:39:04 +02:00

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// Copyright Kevlin Henney, 2000-2005.
// Copyright Alexander Nasonov, 2006-2010.
// Copyright Antony Polukhin, 2011-2019.
//
// 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)
//
// what: lexical_cast custom keyword cast
// who: contributed by Kevlin Henney,
// enhanced with contributions from Terje Slettebo,
// with additional fixes and suggestions from Gennaro Prota,
// Beman Dawes, Dave Abrahams, Daryle Walker, Peter Dimov,
// Alexander Nasonov, Antony Polukhin, Justin Viiret, Michael Hofmann,
// Cheng Yang, Matthew Bradbury, David W. Birdsall, Pavel Korzh and other Boosters
// when: November 2000, March 2003, June 2005, June 2006, March 2011 - 2014
#ifndef BOOST_LEXICAL_CAST_DETAIL_CONVERTER_LEXICAL_HPP
#define BOOST_LEXICAL_CAST_DETAIL_CONVERTER_LEXICAL_HPP
#include <boost/config.hpp>
#ifdef BOOST_HAS_PRAGMA_ONCE
# pragma once
#endif
#if defined(BOOST_NO_STRINGSTREAM) || defined(BOOST_NO_STD_WSTRING)
#define BOOST_LCAST_NO_WCHAR_T
#endif
#include <cstddef>
#include <string>
#include <boost/limits.hpp>
#include <boost/type_traits/integral_constant.hpp>
#include <boost/type_traits/type_identity.hpp>
#include <boost/type_traits/conditional.hpp>
#include <boost/type_traits/is_integral.hpp>
#include <boost/type_traits/is_float.hpp>
#include <boost/type_traits/has_left_shift.hpp>
#include <boost/type_traits/has_right_shift.hpp>
#include <boost/static_assert.hpp>
#include <boost/detail/lcast_precision.hpp>
#include <boost/lexical_cast/detail/widest_char.hpp>
#include <boost/lexical_cast/detail/is_character.hpp>
#ifndef BOOST_NO_CXX11_HDR_ARRAY
#include <array>
#endif
#include <boost/array.hpp>
#include <boost/range/iterator_range_core.hpp>
#include <boost/container/container_fwd.hpp>
#include <boost/lexical_cast/detail/converter_lexical_streams.hpp>
namespace boost {
namespace detail // normalize_single_byte_char<Char>
{
// Converts signed/unsigned char to char
template < class Char >
struct normalize_single_byte_char
{
typedef Char type;
};
template <>
struct normalize_single_byte_char< signed char >
{
typedef char type;
};
template <>
struct normalize_single_byte_char< unsigned char >
{
typedef char type;
};
}
namespace detail // deduce_character_type_later<T>
{
// Helper type, meaning that stram character for T must be deduced
// at Stage 2 (See deduce_source_char<T> and deduce_target_char<T>)
template < class T > struct deduce_character_type_later {};
}
namespace detail // stream_char_common<T>
{
// Selectors to choose stream character type (common for Source and Target)
// Returns one of char, wchar_t, char16_t, char32_t or deduce_character_type_later<T> types
// Executed on Stage 1 (See deduce_source_char<T> and deduce_target_char<T>)
template < typename Type >
struct stream_char_common: public boost::conditional<
boost::detail::is_character< Type >::value,
Type,
boost::detail::deduce_character_type_later< Type >
> {};
template < typename Char >
struct stream_char_common< Char* >: public boost::conditional<
boost::detail::is_character< Char >::value,
Char,
boost::detail::deduce_character_type_later< Char* >
> {};
template < typename Char >
struct stream_char_common< const Char* >: public boost::conditional<
boost::detail::is_character< Char >::value,
Char,
boost::detail::deduce_character_type_later< const Char* >
> {};
template < typename Char >
struct stream_char_common< boost::iterator_range< Char* > >: public boost::conditional<
boost::detail::is_character< Char >::value,
Char,
boost::detail::deduce_character_type_later< boost::iterator_range< Char* > >
> {};
template < typename Char >
struct stream_char_common< boost::iterator_range< const Char* > >: public boost::conditional<
boost::detail::is_character< Char >::value,
Char,
boost::detail::deduce_character_type_later< boost::iterator_range< const Char* > >
> {};
template < class Char, class Traits, class Alloc >
struct stream_char_common< std::basic_string< Char, Traits, Alloc > >
{
typedef Char type;
};
template < class Char, class Traits, class Alloc >
struct stream_char_common< boost::container::basic_string< Char, Traits, Alloc > >
{
typedef Char type;
};
template < typename Char, std::size_t N >
struct stream_char_common< boost::array< Char, N > >: public boost::conditional<
boost::detail::is_character< Char >::value,
Char,
boost::detail::deduce_character_type_later< boost::array< Char, N > >
> {};
template < typename Char, std::size_t N >
struct stream_char_common< boost::array< const Char, N > >: public boost::conditional<
boost::detail::is_character< Char >::value,
Char,
boost::detail::deduce_character_type_later< boost::array< const Char, N > >
> {};
#ifndef BOOST_NO_CXX11_HDR_ARRAY
template < typename Char, std::size_t N >
struct stream_char_common< std::array<Char, N > >: public boost::conditional<
boost::detail::is_character< Char >::value,
Char,
boost::detail::deduce_character_type_later< std::array< Char, N > >
> {};
template < typename Char, std::size_t N >
struct stream_char_common< std::array< const Char, N > >: public boost::conditional<
boost::detail::is_character< Char >::value,
Char,
boost::detail::deduce_character_type_later< std::array< const Char, N > >
> {};
#endif
#ifdef BOOST_HAS_INT128
template <> struct stream_char_common< boost::int128_type >: public boost::type_identity< char > {};
template <> struct stream_char_common< boost::uint128_type >: public boost::type_identity< char > {};
#endif
#if !defined(BOOST_LCAST_NO_WCHAR_T) && defined(BOOST_NO_INTRINSIC_WCHAR_T)
template <>
struct stream_char_common< wchar_t >
{
typedef char type;
};
#endif
}
namespace detail // deduce_source_char_impl<T>
{
// If type T is `deduce_character_type_later` type, then tries to deduce
// character type using boost::has_left_shift<T> metafunction.
// Otherwise supplied type T is a character type, that must be normalized
// using normalize_single_byte_char<Char>.
// Executed at Stage 2 (See deduce_source_char<T> and deduce_target_char<T>)
template < class Char >
struct deduce_source_char_impl
{
typedef BOOST_DEDUCED_TYPENAME boost::detail::normalize_single_byte_char< Char >::type type;
};
template < class T >
struct deduce_source_char_impl< deduce_character_type_later< T > >
{
typedef boost::has_left_shift< std::basic_ostream< char >, T > result_t;
#if defined(BOOST_LCAST_NO_WCHAR_T)
BOOST_STATIC_ASSERT_MSG((result_t::value),
"Source type is not std::ostream`able and std::wostream`s are not supported by your STL implementation");
typedef char type;
#else
typedef BOOST_DEDUCED_TYPENAME boost::conditional<
result_t::value, char, wchar_t
>::type type;
BOOST_STATIC_ASSERT_MSG((result_t::value || boost::has_left_shift< std::basic_ostream< type >, T >::value),
"Source type is neither std::ostream`able nor std::wostream`able");
#endif
};
}
namespace detail // deduce_target_char_impl<T>
{
// If type T is `deduce_character_type_later` type, then tries to deduce
// character type using boost::has_right_shift<T> metafunction.
// Otherwise supplied type T is a character type, that must be normalized
// using normalize_single_byte_char<Char>.
// Executed at Stage 2 (See deduce_source_char<T> and deduce_target_char<T>)
template < class Char >
struct deduce_target_char_impl
{
typedef BOOST_DEDUCED_TYPENAME normalize_single_byte_char< Char >::type type;
};
template < class T >
struct deduce_target_char_impl< deduce_character_type_later<T> >
{
typedef boost::has_right_shift<std::basic_istream<char>, T > result_t;
#if defined(BOOST_LCAST_NO_WCHAR_T)
BOOST_STATIC_ASSERT_MSG((result_t::value),
"Target type is not std::istream`able and std::wistream`s are not supported by your STL implementation");
typedef char type;
#else
typedef BOOST_DEDUCED_TYPENAME boost::conditional<
result_t::value, char, wchar_t
>::type type;
BOOST_STATIC_ASSERT_MSG((result_t::value || boost::has_right_shift<std::basic_istream<wchar_t>, T >::value),
"Target type is neither std::istream`able nor std::wistream`able");
#endif
};
}
namespace detail // deduce_target_char<T> and deduce_source_char<T>
{
// We deduce stream character types in two stages.
//
// Stage 1 is common for Target and Source. At Stage 1 we get
// non normalized character type (may contain unsigned/signed char)
// or deduce_character_type_later<T> where T is the original type.
// Stage 1 is executed by stream_char_common<T>
//
// At Stage 2 we normalize character types or try to deduce character
// type using metafunctions.
// Stage 2 is executed by deduce_target_char_impl<T> and
// deduce_source_char_impl<T>
//
// deduce_target_char<T> and deduce_source_char<T> functions combine
// both stages
template < class T >
struct deduce_target_char
{
typedef BOOST_DEDUCED_TYPENAME stream_char_common< T >::type stage1_type;
typedef BOOST_DEDUCED_TYPENAME deduce_target_char_impl< stage1_type >::type stage2_type;
typedef stage2_type type;
};
template < class T >
struct deduce_source_char
{
typedef BOOST_DEDUCED_TYPENAME stream_char_common< T >::type stage1_type;
typedef BOOST_DEDUCED_TYPENAME deduce_source_char_impl< stage1_type >::type stage2_type;
typedef stage2_type type;
};
}
namespace detail // extract_char_traits template
{
// We are attempting to get char_traits<> from T
// template parameter. Otherwise we'll be using std::char_traits<Char>
template < class Char, class T >
struct extract_char_traits
: boost::false_type
{
typedef std::char_traits< Char > trait_t;
};
template < class Char, class Traits, class Alloc >
struct extract_char_traits< Char, std::basic_string< Char, Traits, Alloc > >
: boost::true_type
{
typedef Traits trait_t;
};
template < class Char, class Traits, class Alloc>
struct extract_char_traits< Char, boost::container::basic_string< Char, Traits, Alloc > >
: boost::true_type
{
typedef Traits trait_t;
};
}
namespace detail // array_to_pointer_decay<T>
{
template<class T>
struct array_to_pointer_decay
{
typedef T type;
};
template<class T, std::size_t N>
struct array_to_pointer_decay<T[N]>
{
typedef const T * type;
};
}
namespace detail // lcast_src_length
{
// Return max. length of string representation of Source;
template< class Source, // Source type of lexical_cast.
class Enable = void // helper type
>
struct lcast_src_length
{
BOOST_STATIC_CONSTANT(std::size_t, value = 1);
};
// Helper for integral types.
// Notes on length calculation:
// Max length for 32bit int with grouping "\1" and thousands_sep ',':
// "-2,1,4,7,4,8,3,6,4,7"
// ^ - is_signed
// ^ - 1 digit not counted by digits10
// ^^^^^^^^^^^^^^^^^^ - digits10 * 2
//
// Constant is_specialized is used instead of constant 1
// to prevent buffer overflow in a rare case when
// <boost/limits.hpp> doesn't add missing specialization for
// numeric_limits<T> for some integral type T.
// When is_specialized is false, the whole expression is 0.
template <class Source>
struct lcast_src_length<
Source, BOOST_DEDUCED_TYPENAME boost::enable_if<boost::is_integral<Source> >::type
>
{
#ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS
BOOST_STATIC_CONSTANT(std::size_t, value =
std::numeric_limits<Source>::is_signed +
std::numeric_limits<Source>::is_specialized + /* == 1 */
std::numeric_limits<Source>::digits10 * 2
);
#else
BOOST_STATIC_CONSTANT(std::size_t, value = 156);
BOOST_STATIC_ASSERT(sizeof(Source) * CHAR_BIT <= 256);
#endif
};
// Helper for floating point types.
// -1.23456789e-123456
// ^ sign
// ^ leading digit
// ^ decimal point
// ^^^^^^^^ lcast_precision<Source>::value
// ^ "e"
// ^ exponent sign
// ^^^^^^ exponent (assumed 6 or less digits)
// sign + leading digit + decimal point + "e" + exponent sign == 5
template<class Source>
struct lcast_src_length<
Source, BOOST_DEDUCED_TYPENAME boost::enable_if<boost::is_float<Source> >::type
>
{
#ifndef BOOST_LCAST_NO_COMPILE_TIME_PRECISION
BOOST_STATIC_ASSERT(
std::numeric_limits<Source>::max_exponent10 <= 999999L &&
std::numeric_limits<Source>::min_exponent10 >= -999999L
);
BOOST_STATIC_CONSTANT(std::size_t, value =
5 + lcast_precision<Source>::value + 6
);
#else // #ifndef BOOST_LCAST_NO_COMPILE_TIME_PRECISION
BOOST_STATIC_CONSTANT(std::size_t, value = 156);
#endif // #ifndef BOOST_LCAST_NO_COMPILE_TIME_PRECISION
};
}
namespace detail // lexical_cast_stream_traits<Source, Target>
{
template <class Source, class Target>
struct lexical_cast_stream_traits {
typedef BOOST_DEDUCED_TYPENAME boost::detail::array_to_pointer_decay<Source>::type src;
typedef BOOST_DEDUCED_TYPENAME boost::remove_cv<src>::type no_cv_src;
typedef boost::detail::deduce_source_char<no_cv_src> deduce_src_char_metafunc;
typedef BOOST_DEDUCED_TYPENAME deduce_src_char_metafunc::type src_char_t;
typedef BOOST_DEDUCED_TYPENAME boost::detail::deduce_target_char<Target>::type target_char_t;
typedef BOOST_DEDUCED_TYPENAME boost::detail::widest_char<
target_char_t, src_char_t
>::type char_type;
#if !defined(BOOST_NO_CXX11_CHAR16_T) && defined(BOOST_NO_CXX11_UNICODE_LITERALS)
BOOST_STATIC_ASSERT_MSG(( !boost::is_same<char16_t, src_char_t>::value
&& !boost::is_same<char16_t, target_char_t>::value),
"Your compiler does not have full support for char16_t" );
#endif
#if !defined(BOOST_NO_CXX11_CHAR32_T) && defined(BOOST_NO_CXX11_UNICODE_LITERALS)
BOOST_STATIC_ASSERT_MSG(( !boost::is_same<char32_t, src_char_t>::value
&& !boost::is_same<char32_t, target_char_t>::value),
"Your compiler does not have full support for char32_t" );
#endif
typedef BOOST_DEDUCED_TYPENAME boost::conditional<
boost::detail::extract_char_traits<char_type, Target>::value,
BOOST_DEDUCED_TYPENAME boost::detail::extract_char_traits<char_type, Target>,
BOOST_DEDUCED_TYPENAME boost::detail::extract_char_traits<char_type, no_cv_src>
>::type::trait_t traits;
typedef boost::integral_constant<
bool,
boost::is_same<char, src_char_t>::value && // source is not a wide character based type
(sizeof(char) != sizeof(target_char_t)) && // target type is based on wide character
(!(boost::detail::is_character<no_cv_src>::value))
> is_string_widening_required_t;
typedef boost::integral_constant<
bool,
!(boost::is_integral<no_cv_src>::value ||
boost::detail::is_character<
BOOST_DEDUCED_TYPENAME deduce_src_char_metafunc::stage1_type // if we did not get character type at stage1
>::value // then we have no optimization for that type
)
> is_source_input_not_optimized_t;
// If we have an optimized conversion for
// Source, we do not need to construct stringbuf.
BOOST_STATIC_CONSTANT(bool, requires_stringbuf =
(is_string_widening_required_t::value || is_source_input_not_optimized_t::value)
);
typedef boost::detail::lcast_src_length<no_cv_src> len_t;
};
}
namespace detail
{
template<typename Target, typename Source>
struct lexical_converter_impl
{
typedef lexical_cast_stream_traits<Source, Target> stream_trait;
typedef detail::lexical_istream_limited_src<
BOOST_DEDUCED_TYPENAME stream_trait::char_type,
BOOST_DEDUCED_TYPENAME stream_trait::traits,
stream_trait::requires_stringbuf,
stream_trait::len_t::value + 1
> i_interpreter_type;
typedef detail::lexical_ostream_limited_src<
BOOST_DEDUCED_TYPENAME stream_trait::char_type,
BOOST_DEDUCED_TYPENAME stream_trait::traits
> o_interpreter_type;
static inline bool try_convert(const Source& arg, Target& result) {
i_interpreter_type i_interpreter;
// Disabling ADL, by directly specifying operators.
if (!(i_interpreter.operator <<(arg)))
return false;
o_interpreter_type out(i_interpreter.cbegin(), i_interpreter.cend());
// Disabling ADL, by directly specifying operators.
if(!(out.operator >>(result)))
return false;
return true;
}
};
}
} // namespace boost
#undef BOOST_LCAST_NO_WCHAR_T
#endif // BOOST_LEXICAL_CAST_DETAIL_CONVERTER_LEXICAL_HPP