__cxx03/__algorithm/fill_n.h

0001 //===----------------------------------------------------------------------===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008
0009 #ifndef _LIBCPP___CXX03___ALGORITHM_FILL_N_H
0010 #define _LIBCPP___CXX03___ALGORITHM_FILL_N_H
0011
0012 #include <__cxx03/__algorithm/min.h>
0013 #include <__cxx03/__config>
0014 #include <__cxx03/__fwd/bit_reference.h>
0015 #include <__cxx03/__iterator/iterator_traits.h>
0016 #include <__cxx03/__memory/pointer_traits.h>
0017 #include <__cxx03/__utility/convert_to_integral.h>
0018
0019 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0020 #  pragma GCC system_header
0021 #endif
0022
0023 _LIBCPP_PUSH_MACROS
0024 #include <__cxx03/__undef_macros>
0025
0026 _LIBCPP_BEGIN_NAMESPACE_STD
0027
0028 // fill_n isn't specialized for std::memset, because the compiler already optimizes the loop to a call to std::memset.
0029
0030 template <class _OutputIterator, class _Size, class _Tp>
0031 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator
0032 __fill_n(_OutputIterator __first, _Size __n, const _Tp& __value);
0033
0034 template <bool _FillVal, class _Cp>
0035 _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
0036 __fill_n_bool(__bit_iterator<_Cp, false> __first, typename _Cp::size_type __n) {
0037   using _It            = __bit_iterator<_Cp, false>;
0038   using __storage_type = typename _It::__storage_type;
0039
0040   const int __bits_per_word = _It::__bits_per_word;
0041   // do first partial word
0042   if (__first.__ctz_ != 0) {
0043     __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
0044     __storage_type __dn    = std::min(__clz_f, __n);
0045     __storage_type __m     = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
0046     if (_FillVal)
0047       *__first.__seg_ |= __m;
0048     else
0049       *__first.__seg_ &= ~__m;
0050     __n -= __dn;
0051     ++__first.__seg_;
0052   }
0053   // do middle whole words
0054   __storage_type __nw = __n / __bits_per_word;
0055   std::__fill_n(std::__to_address(__first.__seg_), __nw, _FillVal ? static_cast<__storage_type>(-1) : 0);
0056   __n -= __nw * __bits_per_word;
0057   // do last partial word
0058   if (__n > 0) {
0059     __first.__seg_ += __nw;
0060     __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
0061     if (_FillVal)
0062       *__first.__seg_ |= __m;
0063     else
0064       *__first.__seg_ &= ~__m;
0065   }
0066 }
0067
0068 template <class _Cp, class _Size>
0069 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __bit_iterator<_Cp, false>
0070 __fill_n(__bit_iterator<_Cp, false> __first, _Size __n, const bool& __value) {
0071   if (__n > 0) {
0072     if (__value)
0073       std::__fill_n_bool<true>(__first, __n);
0074     else
0075       std::__fill_n_bool<false>(__first, __n);
0076   }
0077   return __first + __n;
0078 }
0079
0080 template <class _OutputIterator, class _Size, class _Tp>
0081 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator
0082 __fill_n(_OutputIterator __first, _Size __n, const _Tp& __value) {
0083   for (; __n > 0; ++__first, (void)--__n)
0084     *__first = __value;
0085   return __first;
0086 }
0087
0088 template <class _OutputIterator, class _Size, class _Tp>
0089 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator
0090 fill_n(_OutputIterator __first, _Size __n, const _Tp& __value) {
0091   return std::__fill_n(__first, std::__convert_to_integral(__n), __value);
0092 }
0093
0094 _LIBCPP_END_NAMESPACE_STD
0095
0096 _LIBCPP_POP_MACROS
0097
0098 #endif // _LIBCPP___CXX03___ALGORITHM_FILL_N_H