// -*- C++ -*-
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//===-- parallel_backend_utils.h ------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _PSTL_PARALLEL_BACKEND_UTILS_H
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#define _PSTL_PARALLEL_BACKEND_UTILS_H
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#include <iterator>
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#include <utility>
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#include "utils.h"
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namespace __pstl
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{
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namespace __par_backend
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{
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//! Destroy sequence [xs,xe)
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struct __serial_destroy
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{
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template <typename _RandomAccessIterator>
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void
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operator()(_RandomAccessIterator __zs, _RandomAccessIterator __ze)
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{
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typedef typename std::iterator_traits<_RandomAccessIterator>::value_type _ValueType;
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while (__zs != __ze)
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{
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--__ze;
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(*__ze).~_ValueType();
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}
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}
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};
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//! Merge sequences [__xs,__xe) and [__ys,__ye) to output sequence [__zs,(__xe-__xs)+(__ye-__ys)), using std::move
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template <class _MoveValues, class _MoveSequences>
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struct __serial_move_merge
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{
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const std::size_t _M_nmerge;
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_MoveValues _M_move_values;
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_MoveSequences _M_move_sequences;
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explicit __serial_move_merge(std::size_t __nmerge, _MoveValues __move_values, _MoveSequences __move_sequences)
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: _M_nmerge(__nmerge), _M_move_values(__move_values), _M_move_sequences(__move_sequences)
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{
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}
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template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _RandomAccessIterator3, class _Compare>
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void
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operator()(_RandomAccessIterator1 __xs, _RandomAccessIterator1 __xe, _RandomAccessIterator2 __ys,
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_RandomAccessIterator2 __ye, _RandomAccessIterator3 __zs, _Compare __comp)
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{
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auto __n = _M_nmerge;
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_PSTL_ASSERT(__n > 0);
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if (__xs != __xe)
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{
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if (__ys != __ye)
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{
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for (;;)
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{
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if (__comp(*__ys, *__xs))
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{
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_M_move_values(__ys, __zs);
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++__zs, --__n;
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if (++__ys == __ye)
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{
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break;
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}
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else if (__n == 0)
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{
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__zs = _M_move_sequences(__ys, __ye, __zs);
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break;
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}
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else
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{
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}
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}
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else
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{
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_M_move_values(__xs, __zs);
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++__zs, --__n;
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if (++__xs == __xe)
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{
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_M_move_sequences(__ys, __ye, __zs);
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return;
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}
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else if (__n == 0)
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{
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__zs = _M_move_sequences(__xs, __xe, __zs);
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_M_move_sequences(__ys, __ye, __zs);
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return;
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}
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else
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{
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}
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}
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}
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}
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__ys = __xs;
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__ye = __xe;
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}
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_M_move_sequences(__ys, __ye, __zs);
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}
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};
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template <typename _RandomAccessIterator1, typename _OutputIterator>
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void
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__init_buf(_RandomAccessIterator1 __xs, _RandomAccessIterator1 __xe, _OutputIterator __zs, bool __bMove)
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{
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const _OutputIterator __ze = __zs + (__xe - __xs);
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typedef typename std::iterator_traits<_OutputIterator>::value_type _ValueType;
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if (__bMove)
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{
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// Initialize the temporary buffer and move keys to it.
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for (; __zs != __ze; ++__xs, ++__zs)
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new (&*__zs) _ValueType(std::move(*__xs));
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}
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else
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{
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// Initialize the temporary buffer
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for (; __zs != __ze; ++__zs)
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new (&*__zs) _ValueType;
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}
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}
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// TODO is this actually used anywhere?
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template <typename _Buf>
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class __stack
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{
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typedef typename std::iterator_traits<decltype(_Buf(0).get())>::value_type _ValueType;
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typedef typename std::iterator_traits<_ValueType*>::difference_type _DifferenceType;
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_Buf _M_buf;
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_ValueType* _M_ptr;
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_DifferenceType _M_maxsize;
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__stack(const __stack&) = delete;
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void
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operator=(const __stack&) = delete;
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public:
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__stack(_DifferenceType __max_size) : _M_buf(__max_size), _M_maxsize(__max_size) { _M_ptr = _M_buf.get(); }
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~__stack()
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{
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_PSTL_ASSERT(size() <= _M_maxsize);
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while (!empty())
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pop();
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}
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const _Buf&
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buffer() const
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{
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return _M_buf;
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}
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size_t
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size() const
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{
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_PSTL_ASSERT(_M_ptr - _M_buf.get() <= _M_maxsize);
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_PSTL_ASSERT(_M_ptr - _M_buf.get() >= 0);
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return _M_ptr - _M_buf.get();
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}
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bool
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empty() const
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{
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_PSTL_ASSERT(_M_ptr >= _M_buf.get());
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return _M_ptr == _M_buf.get();
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}
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void
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push(const _ValueType& __v)
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{
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_PSTL_ASSERT(size() < _M_maxsize);
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new (_M_ptr) _ValueType(__v);
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++_M_ptr;
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}
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const _ValueType&
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top() const
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{
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return *(_M_ptr - 1);
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}
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void
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pop()
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{
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_PSTL_ASSERT(_M_ptr > _M_buf.get());
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--_M_ptr;
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(*_M_ptr).~_ValueType();
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}
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};
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} // namespace __par_backend
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} // namespace __pstl
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#endif /* _PSTL_PARALLEL_BACKEND_UTILS_H */
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