Line data    Source code

       1              : //===----------------------------------------------------------------------===//
       2              : //
       3              : // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
       4              : // See https://llvm.org/LICENSE.txt for license information.
       5              : // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
       6              : //
       7              : //===----------------------------------------------------------------------===//
       8              : 
       9              : #ifndef _LIBCPP___ALGORITHM_UNWRAP_ITER_H
      10              : #define _LIBCPP___ALGORITHM_UNWRAP_ITER_H
      11              : 
      12              : #include <__config>
      13              : #include <__iterator/iterator_traits.h>
      14              : #include <__memory/pointer_traits.h>
      15              : #include <__type_traits/enable_if.h>
      16              : #include <__type_traits/is_copy_constructible.h>
      17              : #include <__utility/declval.h>
      18              : #include <__utility/move.h>
      19              : 
      20              : #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
      21              : #  pragma GCC system_header
      22              : #endif
      23              : 
      24              : _LIBCPP_BEGIN_NAMESPACE_STD
      25              : 
      26              : // TODO: Change the name of __unwrap_iter_impl to something more appropriate
      27              : // The job of __unwrap_iter is to remove iterator wrappers (like reverse_iterator or __wrap_iter),
      28              : // to reduce the number of template instantiations and to enable pointer-based optimizations e.g. in std::copy.
      29              : // In debug mode, we don't do this.
      30              : //
      31              : // Some algorithms (e.g. std::copy, but not std::sort) need to convert an
      32              : // "unwrapped" result back into the original iterator type. Doing that is the job of __rewrap_iter.
      33              : 
      34              : // Default case - we can't unwrap anything
      35              : template <class _Iter, bool = __is_cpp17_contiguous_iterator<_Iter>::value>
      36              : struct __unwrap_iter_impl {
      37           54 :   static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Iter __rewrap(_Iter, _Iter __iter) { return __iter; }
      38           81 :   static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Iter __unwrap(_Iter __i) _NOEXCEPT { return __i; }
      39              : };
      40              : 
      41              : #ifndef _LIBCPP_ENABLE_DEBUG_MODE
      42              : 
      43              : // It's a contiguous iterator, so we can use a raw pointer instead
      44              : template <class _Iter>
      45              : struct __unwrap_iter_impl<_Iter, true> {
      46              :   using _ToAddressT = decltype(std::__to_address(std::declval<_Iter>()));
      47              : 
      48         4870 :   static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Iter __rewrap(_Iter __orig_iter, _ToAddressT __unwrapped_iter) {
      49         4870 :     return __orig_iter + (__unwrapped_iter - std::__to_address(__orig_iter));
      50              :   }
      51              : 
      52         7305 :   static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _ToAddressT __unwrap(_Iter __i) _NOEXCEPT {
      53         7305 :     return std::__to_address(__i);
      54              :   }
      55              : };
      56              : 
      57              : #endif // !_LIBCPP_ENABLE_DEBUG_MODE
      58              : 
      59              : template<class _Iter,
      60              :          class _Impl = __unwrap_iter_impl<_Iter>,
      61              :          __enable_if_t<is_copy_constructible<_Iter>::value, int> = 0>
      62              : inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
      63         7386 : decltype(_Impl::__unwrap(std::declval<_Iter>())) __unwrap_iter(_Iter __i) _NOEXCEPT {
      64         7386 :   return _Impl::__unwrap(__i);
      65              : }
      66              : 
      67              : template <class _OrigIter, class _Iter, class _Impl = __unwrap_iter_impl<_OrigIter> >
      68         4924 : _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _OrigIter __rewrap_iter(_OrigIter __orig_iter, _Iter __iter) _NOEXCEPT {
      69         4924 :   return _Impl::__rewrap(std::move(__orig_iter), std::move(__iter));
      70            0 : }
      71              : 
      72              : _LIBCPP_END_NAMESPACE_STD
      73              : 
      74              : #endif // _LIBCPP___ALGORITHM_UNWRAP_ITER_H