libstdc++-v3/include/experimental/functional

// <experimental/functional> -*- C++ -*-

// Copyright (C) 2014-2025 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file experimental/functional
 *  This is a TS C++ Library header.
 *  @ingroup libfund-ts
 */

#ifndef _GLIBCXX_EXPERIMENTAL_FUNCTIONAL
#define _GLIBCXX_EXPERIMENTAL_FUNCTIONAL 1

#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif

#include <bits/requires_hosted.h> // experimental is currently omitted

#if __cplusplus >= 201402L

#include <functional>
#include <tuple>
#include <iterator>
#include <unordered_map>
#include <vector>
#include <array>
#include <bits/stl_algobase.h> // std::max, std::search
#include <experimental/bits/lfts_config.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

namespace experimental
{
inline namespace fundamentals_v1
{
  // See C++14 20.9.9, Function object binders

  /// Variable template for std::is_bind_expression
  template<typename _Tp>
    constexpr bool is_bind_expression_v = std::is_bind_expression<_Tp>::value;

  /// Variable template for std::is_placeholder
  template<typename _Tp>
    constexpr int is_placeholder_v = std::is_placeholder<_Tp>::value;

#define __cpp_lib_experimental_boyer_moore_searching 201411

  // Searchers

  template<typename _ForwardIterator1, typename _BinaryPredicate = equal_to<>>
    class default_searcher
    {
    public:
      default_searcher(_ForwardIterator1 __pat_first,
		       _ForwardIterator1 __pat_last,
		       _BinaryPredicate __pred = _BinaryPredicate())
      : _M_m(__pat_first, __pat_last, std::move(__pred))
      { }

      template<typename _ForwardIterator2>
	_ForwardIterator2
	operator()(_ForwardIterator2 __first, _ForwardIterator2 __last) const
	{
	  return std::search(__first, __last,
			     std::get<0>(_M_m), std::get<1>(_M_m),
			     std::get<2>(_M_m));
	}

    private:
      std::tuple<_ForwardIterator1, _ForwardIterator1, _BinaryPredicate> _M_m;
    };

  template<typename _Key, typename _Tp, typename _Hash, typename _Pred>
    struct __boyer_moore_map_base
    {
      template<typename _RAIter>
	__boyer_moore_map_base(_RAIter __pat, size_t __patlen,
			       _Hash&& __hf, _Pred&& __pred)
	: _M_bad_char{ __patlen, std::move(__hf), std::move(__pred) }
	{
	  if (__patlen > 0)
	    for (__diff_type __i = 0; __i < __patlen - 1; ++__i)
	      _M_bad_char[__pat[__i]] = __patlen - 1 - __i;
	}

      using __diff_type = _Tp;

      __diff_type
      _M_lookup(_Key __key, __diff_type __not_found) const
      {
	auto __iter = _M_bad_char.find(__key);
	if (__iter == _M_bad_char.end())
	  return __not_found;
	return __iter->second;
      }

      _Pred
      _M_pred() const { return _M_bad_char.key_eq(); }

      _GLIBCXX_STD_C::unordered_map<_Key, _Tp, _Hash, _Pred> _M_bad_char;
    };

  template<typename _Tp, size_t _Len, typename _Pred>
    struct __boyer_moore_array_base
    {
      template<typename _RAIter, typename _Unused>
	__boyer_moore_array_base(_RAIter __pat, size_t __patlen,
				 _Unused&&, _Pred&& __pred)
	: _M_bad_char{ std::array<_Tp, _Len>{}, std::move(__pred) }
	{
	  std::get<0>(_M_bad_char).fill(__patlen);
	  if (__patlen > 0)
	    for (__diff_type __i = 0; __i < __patlen - 1; ++__i)
	      {
		auto __ch = __pat[__i];
		using _UCh = std::make_unsigned_t<decltype(__ch)>;
		auto __uch = static_cast<_UCh>(__ch);
		std::get<0>(_M_bad_char)[__uch] = __patlen - 1 - __i;
	      }
	}

      using __diff_type = _Tp;

      template<typename _Key>
	__diff_type
	_M_lookup(_Key __key, __diff_type __not_found) const
	{
	  auto __ukey = static_cast<std::make_unsigned_t<_Key>>(__key);
	  if (__ukey >= _Len)
	    return __not_found;
	  return std::get<0>(_M_bad_char)[__ukey];
	}

      const _Pred&
      _M_pred() const { return std::get<1>(_M_bad_char); }

      std::tuple<std::array<_Tp, _Len>, _Pred> _M_bad_char;
    };

  // Use __boyer_moore_array_base when pattern consists of narrow characters
  // (or std::byte) and uses std::equal_to as the predicate.
  template<typename _RAIter, typename _Hash, typename _Pred,
           typename _Val = typename iterator_traits<_RAIter>::value_type,
	   typename _Diff = typename iterator_traits<_RAIter>::difference_type>
    using __boyer_moore_base_t
      = std::__conditional_t<std::__is_byte_like<_Val, _Pred>::value,
			     __boyer_moore_array_base<_Diff, 256, _Pred>,
			     __boyer_moore_map_base<_Val, _Diff, _Hash, _Pred>>;

  template<typename _RAIter, typename _Hash
	     = std::hash<typename std::iterator_traits<_RAIter>::value_type>,
	   typename _BinaryPredicate = std::equal_to<>>
    class boyer_moore_searcher
    : __boyer_moore_base_t<_RAIter, _Hash, _BinaryPredicate>
    {
      using _Base = __boyer_moore_base_t<_RAIter, _Hash, _BinaryPredicate>;
      using typename _Base::__diff_type;

    public:
      boyer_moore_searcher(_RAIter __pat_first, _RAIter __pat_last,
			   _Hash __hf = _Hash(),
			   _BinaryPredicate __pred = _BinaryPredicate());

      template<typename _RandomAccessIterator2>
	_RandomAccessIterator2
	operator()(_RandomAccessIterator2 __first,
		   _RandomAccessIterator2 __last) const;

    private:
      bool
      _M_is_prefix(_RAIter __word, __diff_type __len,
		   __diff_type __pos)
      {
	const auto& __pred = this->_M_pred();
	__diff_type __suffixlen = __len - __pos;
	for (__diff_type __i = 0; __i < __suffixlen; ++__i)
	  if (!__pred(__word[__i], __word[__pos + __i]))
	    return false;
	return true;
      }

      __diff_type
      _M_suffix_length(_RAIter __word, __diff_type __len,
		       __diff_type __pos)
      {
	const auto& __pred = this->_M_pred();
	__diff_type __i = 0;
	while (__pred(__word[__pos - __i], __word[__len - 1 - __i])
	       && __i < __pos)
	  {
	    ++__i;
	  }
	return __i;
      }

      template<typename _Tp>
	__diff_type
	_M_bad_char_shift(_Tp __c) const
	{ return this->_M_lookup(__c, _M_pat_end - _M_pat); }

      _RAIter _M_pat;
      _RAIter _M_pat_end;
      _GLIBCXX_STD_C::vector<__diff_type> _M_good_suffix;
    };

  template<typename _RAIter, typename _Hash
	     = std::hash<typename std::iterator_traits<_RAIter>::value_type>,
	   typename _BinaryPredicate = std::equal_to<>>
    class boyer_moore_horspool_searcher
    : __boyer_moore_base_t<_RAIter, _Hash, _BinaryPredicate>
    {
      using _Base = __boyer_moore_base_t<_RAIter, _Hash, _BinaryPredicate>;
      using typename _Base::__diff_type;

    public:
      boyer_moore_horspool_searcher(_RAIter __pat,
				    _RAIter __pat_end,
				    _Hash __hf = _Hash(),
				    _BinaryPredicate __pred
				    = _BinaryPredicate())
      : _Base(__pat, __pat_end - __pat, std::move(__hf), std::move(__pred)),
	_M_pat(__pat), _M_pat_end(__pat_end)
      { }

      template<typename _RandomAccessIterator2>
	_RandomAccessIterator2
	operator()(_RandomAccessIterator2 __first,
		   _RandomAccessIterator2 __last) const
	{
	  const auto& __pred = this->_M_pred();
	  auto __patlen = _M_pat_end - _M_pat;
	  if (__patlen == 0)
	    return __first;
	  auto __len = __last - __first;
	  while (__len >= __patlen)
	    {
	      for (auto __scan = __patlen - 1;
		   __pred(__first[__scan], _M_pat[__scan]); --__scan)
		if (__scan == 0)
		  return __first;
	      auto __shift = _M_bad_char_shift(__first[__patlen - 1]);
	      __len -= __shift;
	      __first += __shift;
	    }
	  return __last;
	}

    private:
      template<typename _Tp>
	__diff_type
	_M_bad_char_shift(_Tp __c) const
	{ return this->_M_lookup(__c, _M_pat_end - _M_pat); }

      _RAIter _M_pat;
      _RAIter _M_pat_end;
    };

  /// Generator function for default_searcher
  template<typename _ForwardIterator,
	   typename _BinaryPredicate = std::equal_to<>>
    inline default_searcher<_ForwardIterator, _BinaryPredicate>
    make_default_searcher(_ForwardIterator __pat_first,
			  _ForwardIterator __pat_last,
			  _BinaryPredicate __pred = _BinaryPredicate())
    { return { __pat_first, __pat_last, __pred }; }

  /// Generator function for boyer_moore_searcher
  template<typename _RAIter, typename _Hash
	     = std::hash<typename std::iterator_traits<_RAIter>::value_type>,
	   typename _BinaryPredicate = equal_to<>>
    inline boyer_moore_searcher<_RAIter, _Hash, _BinaryPredicate>
    make_boyer_moore_searcher(_RAIter __pat_first, _RAIter __pat_last,
			      _Hash __hf = _Hash(),
			      _BinaryPredicate __pred = _BinaryPredicate())
    { return { __pat_first, __pat_last, std::move(__hf), std::move(__pred) }; }

  /// Generator function for boyer_moore_horspool_searcher
  template<typename _RAIter, typename _Hash
	     = std::hash<typename std::iterator_traits<_RAIter>::value_type>,
	   typename _BinaryPredicate = equal_to<>>
    inline boyer_moore_horspool_searcher<_RAIter, _Hash, _BinaryPredicate>
    make_boyer_moore_horspool_searcher(_RAIter __pat_first, _RAIter __pat_last,
				       _Hash __hf = _Hash(),
				       _BinaryPredicate __pred
				       = _BinaryPredicate())
    { return { __pat_first, __pat_last, std::move(__hf), std::move(__pred) }; }

  template<typename _RAIter, typename _Hash, typename _BinaryPredicate>
    boyer_moore_searcher<_RAIter, _Hash, _BinaryPredicate>::
    boyer_moore_searcher(_RAIter __pat, _RAIter __pat_end,
			 _Hash __hf, _BinaryPredicate __pred)
    : _Base(__pat, __pat_end - __pat, std::move(__hf), std::move(__pred)),
      _M_pat(__pat), _M_pat_end(__pat_end), _M_good_suffix(__pat_end - __pat)
    {
      auto __patlen = __pat_end - __pat;
      if (__patlen == 0)
	return;
      __diff_type __last_prefix = __patlen - 1;
      for (__diff_type __p = __patlen - 1; __p >= 0; --__p)
	{
	  if (_M_is_prefix(__pat, __patlen, __p + 1))
	    __last_prefix = __p + 1;
	  _M_good_suffix[__p] = __last_prefix + (__patlen - 1 - __p);
	}
      for (__diff_type __p = 0; __p < __patlen - 1; ++__p)
	{
	  auto __slen = _M_suffix_length(__pat, __patlen, __p);
	  auto __pos = __patlen - 1 - __slen;
	  if (!__pred(__pat[__p - __slen], __pat[__pos]))
	    _M_good_suffix[__pos] = __patlen - 1 - __p + __slen;
	}
    }

  template<typename _RAIter, typename _Hash, typename _BinaryPredicate>
  template<typename _RandomAccessIterator2>
    _RandomAccessIterator2
    boyer_moore_searcher<_RAIter, _Hash, _BinaryPredicate>::
    operator()(_RandomAccessIterator2 __first,
	       _RandomAccessIterator2 __last) const
    {
      auto __patlen = _M_pat_end - _M_pat;
      if (__patlen == 0)
	return __first;
      const auto& __pred = this->_M_pred();
      __diff_type __i = __patlen - 1;
      auto __stringlen = __last - __first;
      while (__i < __stringlen)
	{
	  __diff_type __j = __patlen - 1;
	  while (__j >= 0 && __pred(__first[__i], _M_pat[__j]))
	    {
	      --__i;
	      --__j;
	    }
	  if (__j < 0)
	    return __first + __i + 1;
	  __i += std::max(_M_bad_char_shift(__first[__i]),
			  _M_good_suffix[__j]);
	}
      return __last;
    }
} // namespace fundamentals_v1

inline namespace fundamentals_v2
{
#define __cpp_lib_experimental_not_fn 201406

  /// [func.not_fn] Function template not_fn
  template<typename _Fn>
    inline auto
    not_fn(_Fn&& __fn)
    noexcept(std::is_nothrow_constructible<std::decay_t<_Fn>, _Fn&&>::value)
    {
      return std::_Not_fn<std::decay_t<_Fn>>{std::forward<_Fn>(__fn), 0};
    }
} // namespace fundamentals_v2
} // namespace experimental

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif // C++14

#endif // _GLIBCXX_EXPERIMENTAL_FUNCTIONAL