forked from boostorg/iterator
Removed workarounds for older compilers from counting_iterator.hpp.
This commit is contained in:
Andrey Semashev
@ -5,209 +5,171 @@
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#ifndef COUNTING_ITERATOR_DWA200348_HPP
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#define COUNTING_ITERATOR_DWA200348_HPP
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#include <limits>
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#include <type_traits>
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#include <boost/config.hpp>
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#include <boost/detail/workaround.hpp>
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#ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS
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#include <limits>
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#endif
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#include <boost/core/use_default.hpp>
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#include <boost/detail/numeric_traits.hpp>
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#include <boost/iterator/iterator_adaptor.hpp>
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#include <boost/iterator/iterator_categories.hpp>
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#include <boost/iterator/detail/type_traits/type_identity.hpp>
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namespace boost {
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namespace iterators {
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template <
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class Incrementable
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, class CategoryOrTraversal
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, class Difference
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template<
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class Incrementable,
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class CategoryOrTraversal,
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class Difference
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>
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class counting_iterator;
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namespace detail
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namespace detail {
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// Try to detect numeric types at compile time in ways compatible
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// with the limitations of the compiler and library.
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template <class T>
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struct is_numeric :
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public std::integral_constant<bool, std::numeric_limits<T>::is_specialized>
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{};
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template <>
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struct is_numeric<long long> :
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public std::true_type
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{};
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template <>
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struct is_numeric<unsigned long long> :
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public std::true_type
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{};
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#if defined(BOOST_HAS_INT128)
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template <>
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struct is_numeric<boost::int128_type> :
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public std::true_type
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{};
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template <>
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struct is_numeric<boost::uint128_type> :
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public std::true_type
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{};
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#endif
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// Some compilers fail to have a numeric_limits specialization
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template <>
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struct is_numeric<wchar_t> :
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public std::true_type
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{};
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template <class T>
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struct numeric_difference
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{
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// Try to detect numeric types at compile time in ways compatible
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// with the limitations of the compiler and library.
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template <class T>
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struct is_numeric_impl
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{
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#ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS
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BOOST_STATIC_CONSTANT(bool, value = std::numeric_limits<T>::is_specialized);
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#else
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#if !BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x551))
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BOOST_STATIC_CONSTANT(
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bool, value = (
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std::is_convertible<int,T>::value
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&& std::is_convertible<T,int>::value
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));
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#else
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BOOST_STATIC_CONSTANT(bool, value = std::is_arithmetic<T>::value);
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#endif
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#endif
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};
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template <class T>
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struct is_numeric
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: std::integral_constant<bool, ::boost::iterators::detail::is_numeric_impl<T>::value>
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{};
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template <>
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struct is_numeric<long long>
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: std::true_type {};
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template <>
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struct is_numeric<unsigned long long>
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: std::true_type {};
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using type = typename boost::detail::numeric_traits<T>::difference_type;
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};
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#if defined(BOOST_HAS_INT128)
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template <>
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struct is_numeric<boost::int128_type>
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: std::true_type {};
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// std::numeric_limits, which is used by numeric_traits, is not specialized for __int128 in some standard libraries
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template <>
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struct numeric_difference<boost::int128_type>
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{
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using type = boost::int128_type;
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};
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template <>
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struct is_numeric<boost::uint128_type>
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: std::true_type {};
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template <>
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struct numeric_difference<boost::uint128_type>
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{
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using type = boost::int128_type;
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};
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#endif
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// Some compilers fail to have a numeric_limits specialization
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template <>
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struct is_numeric<wchar_t>
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: std::true_type {};
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template <class Incrementable, class CategoryOrTraversal, class Difference>
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struct counting_iterator_base
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{
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using traversal = typename detail::ia_dflt_help<
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CategoryOrTraversal,
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typename std::conditional<
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is_numeric<Incrementable>::value,
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iterators::detail::type_identity<random_access_traversal_tag>,
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iterator_traversal<Incrementable>
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>::type
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>::type;
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template <class T>
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struct numeric_difference
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{
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typedef typename boost::detail::numeric_traits<T>::difference_type type;
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};
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using difference = typename detail::ia_dflt_help<
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Difference,
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typename std::conditional<
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is_numeric<Incrementable>::value,
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numeric_difference<Incrementable>,
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iterator_difference<Incrementable>
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>::type
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>::type;
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#if defined(BOOST_HAS_INT128)
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// std::numeric_limits, which is used by numeric_traits, is not specialized for __int128 in some standard libraries
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template <>
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struct numeric_difference<boost::int128_type>
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{
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typedef boost::int128_type type;
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};
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template <>
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struct numeric_difference<boost::uint128_type>
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{
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typedef boost::int128_type type;
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};
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#endif
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template <class Incrementable, class CategoryOrTraversal, class Difference>
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struct counting_iterator_base
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{
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typedef typename detail::ia_dflt_help<
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CategoryOrTraversal
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, typename std::conditional<
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is_numeric<Incrementable>::value
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, iterators::detail::type_identity<random_access_traversal_tag>
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, iterator_traversal<Incrementable>
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>::type
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>::type traversal;
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typedef typename detail::ia_dflt_help<
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Difference
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, typename std::conditional<
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is_numeric<Incrementable>::value
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, numeric_difference<Incrementable>
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, iterator_difference<Incrementable>
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>::type
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>::type difference;
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typedef iterator_adaptor<
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counting_iterator<Incrementable, CategoryOrTraversal, Difference> // self
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, Incrementable // Base
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, Incrementable // Value
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using type = iterator_adaptor<
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counting_iterator<Incrementable, CategoryOrTraversal, Difference>, // self
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Incrementable, // Base
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#ifndef BOOST_ITERATOR_REF_CONSTNESS_KILLS_WRITABILITY
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const // MSVC won't strip this. Instead we enable Thomas'
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// criterion (see boost/iterator/detail/facade_iterator_category.hpp)
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const // MSVC won't strip this. Instead we enable Thomas'
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// criterion (see boost/iterator/detail/facade_iterator_category.hpp)
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#endif
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, traversal
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, Incrementable const& // reference
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, difference
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> type;
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};
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Incrementable, // Value
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traversal,
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Incrementable const&, // reference
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difference
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>;
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};
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// Template class distance_policy_select -- choose a policy for computing the
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// distance between counting_iterators at compile-time based on whether or not
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// the iterator wraps an integer or an iterator, using "poor man's partial
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// specialization".
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template <bool is_integer> struct distance_policy_select;
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// A policy for wrapped iterators
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template <class Difference, class Incrementable1, class Incrementable2>
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struct iterator_distance
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{
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static Difference distance(Incrementable1 x, Incrementable2 y)
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{
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return y - x;
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}
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};
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// A policy for wrapped numbers
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template <class Difference, class Incrementable1, class Incrementable2>
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struct number_distance
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{
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static Difference distance(Incrementable1 x, Incrementable2 y)
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{
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return boost::detail::numeric_distance(x, y);
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}
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};
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}
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template <
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class Incrementable
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, class CategoryOrTraversal = use_default
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, class Difference = use_default
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>
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class counting_iterator
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: public detail::counting_iterator_base<
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Incrementable, CategoryOrTraversal, Difference
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>::type
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// A distance calculation policy for wrapped iterators
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template <class Difference, class Incrementable1, class Incrementable2>
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struct iterator_distance
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{
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typedef typename detail::counting_iterator_base<
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static Difference distance(Incrementable1 x, Incrementable2 y)
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{
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return y - x;
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}
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};
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// A distance calculation policy for wrapped numbers
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template <class Difference, class Incrementable1, class Incrementable2>
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struct number_distance
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{
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static Difference distance(Incrementable1 x, Incrementable2 y)
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{
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return boost::detail::numeric_distance(x, y);
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}
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};
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} // namespace detail
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template<
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class Incrementable,
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class CategoryOrTraversal = use_default,
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class Difference = use_default
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>
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class counting_iterator :
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public detail::counting_iterator_base<Incrementable, CategoryOrTraversal, Difference>::type
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{
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using super_t = typename detail::counting_iterator_base<
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Incrementable, CategoryOrTraversal, Difference
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>::type super_t;
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>::type;
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friend class iterator_core_access;
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public:
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typedef typename super_t::difference_type difference_type;
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public:
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using reference = typename super_t::reference;
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using difference_type = typename super_t::difference_type;
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BOOST_DEFAULTED_FUNCTION(counting_iterator(), {})
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counting_iterator() = default;
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BOOST_DEFAULTED_FUNCTION(counting_iterator(counting_iterator const& rhs), : super_t(rhs.base()) {})
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counting_iterator(counting_iterator const&) = default;
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counting_iterator& operator=(counting_iterator const&) = default;
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counting_iterator(Incrementable x)
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: super_t(x)
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counting_iterator(Incrementable x) :
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super_t(x)
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{
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}
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#if 0
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template<class OtherIncrementable>
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counting_iterator(
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counting_iterator<OtherIncrementable, CategoryOrTraversal, Difference> const& t
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, typename enable_if_convertible<OtherIncrementable, Incrementable>::type* = 0
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)
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: super_t(t.base())
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{}
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#endif
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BOOST_DEFAULTED_FUNCTION(counting_iterator& operator=(counting_iterator const& rhs), { *static_cast< super_t* >(this) = static_cast< super_t const& >(rhs); return *this; })
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private:
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typename super_t::reference dereference() const
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private:
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reference dereference() const
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{
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return this->base_reference();
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}
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@ -216,23 +178,21 @@ class counting_iterator
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difference_type
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distance_to(counting_iterator<OtherIncrementable, CategoryOrTraversal, Difference> const& y) const
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{
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typedef typename std::conditional<
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detail::is_numeric<Incrementable>::value
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, detail::number_distance<difference_type, Incrementable, OtherIncrementable>
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, detail::iterator_distance<difference_type, Incrementable, OtherIncrementable>
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>::type d;
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using distance_traits = typename std::conditional<
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detail::is_numeric<Incrementable>::value,
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detail::number_distance<difference_type, Incrementable, OtherIncrementable>,
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detail::iterator_distance<difference_type, Incrementable, OtherIncrementable>
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>::type;
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return d::distance(this->base(), y.base());
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return distance_traits::distance(this->base(), y.base());
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}
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};
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// Manufacture a counting iterator for an arbitrary incrementable type
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template <class Incrementable>
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inline counting_iterator<Incrementable>
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make_counting_iterator(Incrementable x)
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inline counting_iterator<Incrementable> make_counting_iterator(Incrementable x)
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{
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typedef counting_iterator<Incrementable> result_t;
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return result_t(x);
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return counting_iterator<Incrementable>(x);
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}
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} // namespace iterators
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