| //===----------------------------------------------------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef _LIBCPP___ALGORITHM_UNWRAP_ITER_H |
| #define _LIBCPP___ALGORITHM_UNWRAP_ITER_H |
| |
| #include <__config> |
| #include <__iterator/iterator_traits.h> |
| #include <__memory/pointer_traits.h> |
| #include <__type_traits/enable_if.h> |
| #include <__type_traits/is_copy_constructible.h> |
| #include <__utility/declval.h> |
| #include <__utility/move.h> |
| |
| #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
| # pragma GCC system_header |
| #endif |
| |
| _LIBCPP_BEGIN_NAMESPACE_STD |
| |
| // TODO: Change the name of __unwrap_iter_impl to something more appropriate |
| // The job of __unwrap_iter is to remove iterator wrappers (like reverse_iterator or __wrap_iter), |
| // to reduce the number of template instantiations and to enable pointer-based optimizations e.g. in std::copy. |
| // In debug mode, we don't do this. |
| // |
| // Some algorithms (e.g. std::copy, but not std::sort) need to convert an |
| // "unwrapped" result back into the original iterator type. Doing that is the job of __rewrap_iter. |
| |
| // Default case - we can't unwrap anything |
| template <class _Iter, bool = __is_cpp17_contiguous_iterator<_Iter>::value> |
| struct __unwrap_iter_impl { |
| static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Iter __rewrap(_Iter, _Iter __iter) { return __iter; } |
| static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Iter __unwrap(_Iter __i) _NOEXCEPT { return __i; } |
| }; |
| |
| #ifndef _LIBCPP_ENABLE_DEBUG_MODE |
| |
| // It's a contiguous iterator, so we can use a raw pointer instead |
| template <class _Iter> |
| struct __unwrap_iter_impl<_Iter, true> { |
| using _ToAddressT = decltype(std::__to_address(std::declval<_Iter>())); |
| |
| static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Iter __rewrap(_Iter __orig_iter, _ToAddressT __unwrapped_iter) { |
| return __orig_iter + (__unwrapped_iter - std::__to_address(__orig_iter)); |
| } |
| |
| static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _ToAddressT __unwrap(_Iter __i) _NOEXCEPT { |
| return std::__to_address(__i); |
| } |
| }; |
| |
| #endif // !_LIBCPP_ENABLE_DEBUG_MODE |
| |
| template<class _Iter, |
| class _Impl = __unwrap_iter_impl<_Iter>, |
| __enable_if_t<is_copy_constructible<_Iter>::value, int> = 0> |
| inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 |
| decltype(_Impl::__unwrap(std::declval<_Iter>())) __unwrap_iter(_Iter __i) _NOEXCEPT { |
| return _Impl::__unwrap(__i); |
| } |
| |
| // Allow input_iterators to be passed to __unwrap_iter (but not __rewrap_iter) |
| #if _LIBCPP_STD_VER >= 20 |
| template <class _Iter, __enable_if_t<!is_copy_constructible<_Iter>::value, int> = 0> |
| inline _LIBCPP_HIDE_FROM_ABI constexpr _Iter __unwrap_iter(_Iter __i) noexcept { |
| return __i; |
| } |
| #endif |
| |
| template <class _OrigIter, class _Iter, class _Impl = __unwrap_iter_impl<_OrigIter> > |
| _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _OrigIter __rewrap_iter(_OrigIter __orig_iter, _Iter __iter) _NOEXCEPT { |
| return _Impl::__rewrap(std::move(__orig_iter), std::move(__iter)); |
| } |
| |
| _LIBCPP_END_NAMESPACE_STD |
| |
| #endif // _LIBCPP___ALGORITHM_UNWRAP_ITER_H |