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cat -n /usr/include/c++/15/bits/forward_list.tcc

     1	// <forward_list.tcc> -*- C++ -*-
     2	
     3	// Copyright (C) 2008-2025 Free Software Foundation, Inc.
     4	//
     5	// This file is part of the GNU ISO C++ Library.  This library is free
     6	// software; you can redistribute it and/or modify it under the
     7	// terms of the GNU General Public License as published by the
     8	// Free Software Foundation; either version 3, or (at your option)
     9	// any later version.
    10	
    11	// This library is distributed in the hope that it will be useful,
    12	// but WITHOUT ANY WARRANTY; without even the implied warranty of
    13	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    14	// GNU General Public License for more details.
    15	
    16	// Under Section 7 of GPL version 3, you are granted additional
    17	// permissions described in the GCC Runtime Library Exception, version
    18	// 3.1, as published by the Free Software Foundation.
    19	
    20	// You should have received a copy of the GNU General Public License and
    21	// a copy of the GCC Runtime Library Exception along with this program;
    22	// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
    23	// <http://www.gnu.org/licenses/>.
    24	
    25	/** @file bits/forward_list.tcc
    26	 *  This is an internal header file, included by other library headers.
    27	 *  Do not attempt to use it directly. @headername{forward_list}
    28	 */
    29	
    30	#ifndef _FORWARD_LIST_TCC
    31	#define _FORWARD_LIST_TCC 1
    32	
    33	namespace std _GLIBCXX_VISIBILITY(default)
    34	{
    35	_GLIBCXX_BEGIN_NAMESPACE_VERSION
    36	_GLIBCXX_BEGIN_NAMESPACE_CONTAINER
    37	
    38	  template<typename _Tp, typename _Alloc>
    39	    _Fwd_list_base<_Tp, _Alloc>::
    40	    _Fwd_list_base(_Fwd_list_base&& __lst, _Node_alloc_type&& __a)
    41	    : _M_impl(std::move(__a))
    42	    {
    43	      if (__lst._M_get_Node_allocator() == _M_get_Node_allocator())
    44		this->_M_impl._M_head = std::move(__lst._M_impl._M_head);
    45	    }
    46	
    47	  template<typename _Tp, typename _Alloc>
    48	    template<typename... _Args>
    49	      auto
    50	      _Fwd_list_base<_Tp, _Alloc>::
    51	      _M_insert_after(const_iterator __pos, _Args&&... __args)
    52	      -> _Base_ptr
    53	      {
    54		auto __to = __pos._M_const_cast()._M_node;
    55		_Node_ptr __thing = _M_create_node(std::forward<_Args>(__args)...);
    56		__thing->_M_next = __to->_M_next;
    57		__to->_M_next = __thing->_M_base_ptr();
    58		return __to->_M_next;
    59	      }
    60	
    61	  template<typename _Tp, typename _Alloc>
    62	    auto
    63	    _Fwd_list_base<_Tp, _Alloc>::
    64	    _M_erase_after(_Base_ptr __pos)
    65	    -> _Base_ptr
    66	    {
    67	      auto& __curr = static_cast<_Node&>(*__pos->_M_next);
    68	      __pos->_M_next = __curr._M_next;
    69	      _M_destroy_node(__curr._M_node_ptr());
    70	      return __pos->_M_next;
    71	    }
    72	
    73	  template<typename _Tp, typename _Alloc>
    74	    auto
    75	    _Fwd_list_base<_Tp, _Alloc>::
    76	    _M_erase_after(_Base_ptr __pos, _Base_ptr __last)
    77	    -> _Base_ptr
    78	    {
    79	      _Base_ptr __curr = __pos->_M_next;
    80	      while (__curr != __last)
    81		{
    82		  auto& __node = static_cast<_Node&>(*__curr);
    83		  __curr = __curr->_M_next;
    84		  _M_destroy_node(__node._M_node_ptr());
    85		}
    86	      __pos->_M_next = __last;
    87	      return __last;
    88	    }
    89	
    90	  // Called by the range constructor to implement [23.3.4.2]/9
    91	  template<typename _Tp, typename _Alloc>
    92	    template<typename _InputIterator>
    93	      void
    94	      forward_list<_Tp, _Alloc>::
    95	      _M_range_initialize(_InputIterator __first, _InputIterator __last)
    96	      {
    97		auto __to = this->_M_impl._M_head._M_base_ptr();
    98		for (; __first != __last; ++__first)
    99		  {
   100		    __to->_M_next = this->_M_create_node(*__first)->_M_base_ptr();
   101		    __to = __to->_M_next;
   102		  }
   103	      }
   104	
   105	  // Called by forward_list(n,v,a).
   106	  template<typename _Tp, typename _Alloc>
   107	    void
   108	    forward_list<_Tp, _Alloc>::
   109	    _M_fill_initialize(size_type __n, const value_type& __value)
   110	    {
   111	      auto __to = this->_M_impl._M_head._M_base_ptr();
   112	      for (; __n; --__n)
   113		{
   114		  __to->_M_next = this->_M_create_node(__value)->_M_base_ptr();
   115		  __to = __to->_M_next;
   116		}
   117	    }
   118	
   119	  template<typename _Tp, typename _Alloc>
   120	    void
   121	    forward_list<_Tp, _Alloc>::
   122	    _M_default_initialize(size_type __n)
   123	    {
   124	      auto __to = this->_M_impl._M_head._M_base_ptr();
   125	      for (; __n; --__n)
   126		{
   127		  __to->_M_next = this->_M_create_node()->_M_base_ptr();
   128		  __to = __to->_M_next;
   129		}
   130	    }
   131	
   132	  template<typename _Tp, typename _Alloc>
   133	    forward_list<_Tp, _Alloc>&
   134	    forward_list<_Tp, _Alloc>::
   135	    operator=(const forward_list& __list)
   136	    {
   137	      if (std::__addressof(__list) != this)
   138		{
   139		  if (_Node_alloc_traits::_S_propagate_on_copy_assign())
   140		    {
   141		      auto& __this_alloc = this->_M_get_Node_allocator();
   142		      auto& __that_alloc = __list._M_get_Node_allocator();
   143		      if (!_Node_alloc_traits::_S_always_equal()
   144			  && __this_alloc != __that_alloc)
   145			{
   146			  // replacement allocator cannot free existing storage
   147			  clear();
   148			}
   149		      std::__alloc_on_copy(__this_alloc, __that_alloc);
   150		    }
   151		  assign(__list.cbegin(), __list.cend());
   152		}
   153	      return *this;
   154	    }
   155	
   156	  template<typename _Tp, typename _Alloc>
   157	    void
   158	    forward_list<_Tp, _Alloc>::
   159	    _M_default_insert_after(const_iterator __pos, size_type __n)
   160	    {
   161	      const_iterator __saved_pos = __pos;
   162	      __try
   163		{
   164		  for (; __n; --__n)
   165		    __pos = emplace_after(__pos);
   166		}
   167	      __catch(...)
   168		{
   169		  erase_after(__saved_pos, ++__pos);
   170		  __throw_exception_again;
   171		}
   172	    }
   173	
   174	  template<typename _Tp, typename _Alloc>
   175	    void
   176	    forward_list<_Tp, _Alloc>::
   177	    resize(size_type __sz)
   178	    {
   179	      iterator __k = before_begin();
   180	
   181	      size_type __len = 0;
   182	      while (__k._M_next() != end() && __len < __sz)
   183		{
   184		  ++__k;
   185		  ++__len;
   186		}
   187	      if (__len == __sz)
   188		erase_after(__k, end());
   189	      else
   190		_M_default_insert_after(__k, __sz - __len);
   191	    }
   192	
   193	  template<typename _Tp, typename _Alloc>
   194	    void
   195	    forward_list<_Tp, _Alloc>::
   196	    resize(size_type __sz, const value_type& __val)
   197	    {
   198	      iterator __k = before_begin();
   199	
   200	      size_type __len = 0;
   201	      while (__k._M_next() != end() && __len < __sz)
   202		{
   203		  ++__k;
   204		  ++__len;
   205		}
   206	      if (__len == __sz)
   207		erase_after(__k, end());
   208	      else
   209		insert_after(__k, __sz - __len, __val);
   210	    }
   211	
   212	  template<typename _Tp, typename _Alloc>
   213	    typename forward_list<_Tp, _Alloc>::iterator
   214	    forward_list<_Tp, _Alloc>::
   215	    _M_splice_after(const_iterator __pos,
   216			    const_iterator __before, const_iterator __last)
   217	    {
   218	      auto __tmp = __pos._M_const_cast()._M_node;
   219	      auto __b = __before._M_const_cast()._M_node;
   220	      auto __end = __b;
   221	
   222	      while (__end && __end->_M_next != __last._M_node)
   223		__end = __end->_M_next;
   224	
   225	      if (__b != __end)
   226		return iterator(__tmp->_M_transfer_after(__b, __end));
   227	      else
   228		return iterator(__tmp);
   229	    }
   230	
   231	  template<typename _Tp, typename _Alloc>
   232	    void
   233	    forward_list<_Tp, _Alloc>::
   234	    splice_after(const_iterator __pos, forward_list&&,
   235			 const_iterator __i) noexcept
   236	    {
   237	      const_iterator __j = __i;
   238	      ++__j;
   239	
   240	      if (__pos == __i || __pos == __j)
   241		return;
   242	
   243	      auto __tmp = __pos._M_const_cast()._M_node;
   244	      __tmp->_M_transfer_after(__i._M_const_cast()._M_node,
   245				       __j._M_const_cast()._M_node);
   246	    }
   247	
   248	  template<typename _Tp, typename _Alloc>
   249	    typename forward_list<_Tp, _Alloc>::iterator
   250	    forward_list<_Tp, _Alloc>::
   251	    insert_after(const_iterator __pos, size_type __n, const _Tp& __val)
   252	    {
   253	      if (__n)
   254		{
   255		  forward_list __tmp(__n, __val, get_allocator());
   256		  return _M_splice_after(__pos, __tmp.before_begin(), __tmp.end());
   257		}
   258	      else
   259		return __pos._M_const_cast();
   260	    }
   261	
   262	  template<typename _Tp, typename _Alloc>
   263	    template<typename _InputIterator, typename>
   264	      typename forward_list<_Tp, _Alloc>::iterator
   265	      forward_list<_Tp, _Alloc>::
   266	      insert_after(const_iterator __pos,
   267			   _InputIterator __first, _InputIterator __last)
   268	      {
   269		forward_list __tmp(__first, __last, get_allocator());
   270		if (!__tmp.empty())
   271		  return _M_splice_after(__pos, __tmp.before_begin(), __tmp.end());
   272		else
   273		  return __pos._M_const_cast();
   274	      }
   275	
   276	#if __cplusplus > 201703L
   277	# define _GLIBCXX20_ONLY(__expr) __expr
   278	#else
   279	# define _GLIBCXX20_ONLY(__expr)
   280	#endif
   281	
   282	  template<typename _Tp, typename _Alloc>
   283	    auto
   284	    forward_list<_Tp, _Alloc>::
   285	    remove(const _Tp& __val) -> __remove_return_type
   286	    {
   287	      size_type __removed __attribute__((__unused__)) = 0;
   288	      forward_list __to_destroy(get_allocator());
   289	
   290	      auto __prev_it = cbefore_begin();
   291	      while (auto __tmp = __prev_it._M_node->_M_next)
   292		if (*static_cast<_Node&>(*__tmp)._M_valptr() == __val)
   293		  {
   294		    __to_destroy.splice_after(__to_destroy.cbefore_begin(),
   295					      *this, __prev_it);
   296		    _GLIBCXX20_ONLY( __removed++ );
   297		  }
   298		else
   299		  ++__prev_it;
   300	
   301	      return _GLIBCXX20_ONLY( __removed );
   302	    }
   303	
   304	  template<typename _Tp, typename _Alloc>
   305	    template<typename _Pred>
   306	      auto
   307	      forward_list<_Tp, _Alloc>::
   308	      remove_if(_Pred __pred) -> __remove_return_type
   309	      {
   310		size_type __removed __attribute__((__unused__)) = 0;
   311		forward_list __to_destroy(get_allocator());
   312	
   313		auto __prev_it = cbefore_begin();
   314		while (auto __tmp = __prev_it._M_node->_M_next)
   315		  if (__pred(*static_cast<_Node&>(*__tmp)._M_valptr()))
   316		    {
   317		      __to_destroy.splice_after(__to_destroy.cbefore_begin(),
   318						*this, __prev_it);
   319		      _GLIBCXX20_ONLY( __removed++ );
   320		    }
   321		  else
   322		    ++__prev_it;
   323	
   324		return _GLIBCXX20_ONLY( __removed );
   325	      }
   326	
   327	  template<typename _Tp, typename _Alloc>
   328	    template<typename _BinPred>
   329	      auto
   330	      forward_list<_Tp, _Alloc>::
   331	      unique(_BinPred __binary_pred) -> __remove_return_type
   332	      {
   333		iterator __first = begin();
   334		iterator __last = end();
   335		if (__first == __last)
   336		  return _GLIBCXX20_ONLY(0);
   337	
   338		forward_list __to_destroy(get_allocator());
   339		size_type __removed __attribute__((__unused__)) = 0;
   340		iterator __next = __first;
   341		while (++__next != __last)
   342		{
   343		  if (__binary_pred(*__first, *__next))
   344		    {
   345		      __to_destroy.splice_after(__to_destroy.cbefore_begin(),
   346						*this, __first);
   347		      _GLIBCXX20_ONLY( __removed++ );
   348		    }
   349		  else
   350		    __first = __next;
   351		  __next = __first;
   352		}
   353	
   354		return _GLIBCXX20_ONLY( __removed );
   355	      }
   356	
   357	#undef _GLIBCXX20_ONLY
   358	
   359	  template<typename _Tp, typename _Alloc>
   360	    template<typename _Comp>
   361	      void
   362	      forward_list<_Tp, _Alloc>::
   363	      merge(forward_list&& __list, _Comp __comp)
   364	      {
   365		// _GLIBCXX_RESOLVE_LIB_DEFECTS
   366		// 3088. forward_list::merge behavior unclear when passed *this
   367		if (std::__addressof(__list) == this)
   368		  return;
   369	
   370		using _Base_ptr = typename _Node::_Base_ptr;
   371	
   372		_Base_ptr __node = this->_M_impl._M_head._M_base_ptr();
   373		_Base_ptr __other = __list._M_impl._M_head._M_base_ptr();
   374		while (__node->_M_next && __other->_M_next)
   375		  {
   376		    auto& __l = static_cast<_Node&>(*__other->_M_next);
   377		    auto& __r = static_cast<_Node&>(*__node->_M_next);
   378		    if (__comp(*__l._M_valptr(), *__r._M_valptr()))
   379		      __node->_M_transfer_after(__other, __other->_M_next);
   380		    __node = __node->_M_next;
   381		  }
   382	
   383		if (__list._M_impl._M_head._M_next)
   384		  *__node = std::move(__list._M_impl._M_head);
   385	      }
   386	
   387	  template<typename _Tp, typename _Alloc>
   388	    bool
   389	    operator==(const forward_list<_Tp, _Alloc>& __lx,
   390		       const forward_list<_Tp, _Alloc>& __ly)
   391	    {
   392	      //  We don't have size() so we need to walk through both lists
   393	      //  making sure both iterators are valid.
   394	      auto __ix = __lx.cbegin();
   395	      auto __iy = __ly.cbegin();
   396	      while (__ix != __lx.cend() && __iy != __ly.cend())
   397		{
   398		  if (!(*__ix == *__iy))
   399		    return false;
   400		  ++__ix;
   401		  ++__iy;
   402		}
   403	      if (__ix == __lx.cend() && __iy == __ly.cend())
   404		return true;
   405	      else
   406		return false;
   407	    }
   408	
   409	  template<typename _Tp, class _Alloc>
   410	    template<typename _Comp>
   411	      void
   412	      forward_list<_Tp, _Alloc>::
   413	      sort(_Comp __comp)
   414	      {
   415		if (empty())
   416		  return;
   417	
   418		using _Base_ptr = typename _Node::_Base_ptr;
   419	
   420		// If `next' is nullptr, return immediately.
   421		_Base_ptr __list = this->_M_impl._M_head._M_next;
   422	
   423		unsigned long __insize = 1;
   424	
   425		while (1)
   426		  {
   427		    _Base_ptr __p = __list;
   428		    __list = nullptr;
   429		    _Base_ptr __tail = nullptr;
   430	
   431		    // Count number of merges we do in this pass.
   432		    unsigned long __nmerges = 0;
   433	
   434		    while (__p)
   435		      {
   436			++__nmerges;
   437			// There exists a merge to be done.
   438			// Step `insize' places along from p.
   439			_Base_ptr __q = __p;
   440			unsigned long __psize = 0;
   441			for (unsigned long __i = 0; __i < __insize; ++__i)
   442			  {
   443			    ++__psize;
   444			    __q = __q->_M_next;
   445			    if (!__q)
   446			      break;
   447			  }
   448	
   449			// If q hasn't fallen off end, we have two lists to merge.
   450			unsigned long __qsize = __insize;
   451	
   452			// Now we have two lists; merge them.
   453			while (__psize > 0 || (__qsize > 0 && __q))
   454			  {
   455			    // Decide whether next node of merge comes from p or q.
   456			    _Base_ptr __e;
   457			    if (__psize == 0)
   458			      {
   459				// p is empty; e must come from q.
   460				__e = __q;
   461				__q = __q->_M_next;
   462				--__qsize;
   463			      }
   464			    else if (__qsize == 0 || !__q)
   465			      {
   466				// q is empty; e must come from p.
   467				__e = __p;
   468				__p = __p->_M_next;
   469				--__psize;
   470			      }
   471			    else if (!__comp(*static_cast<_Node&>(*__q)._M_valptr(),
   472					     *static_cast<_Node&>(*__p)._M_valptr()))
   473			      {
   474				// First node of q is not lower; e must come from p.
   475				__e = __p;
   476				__p = __p->_M_next;
   477				--__psize;
   478			      }
   479			    else
   480			      {
   481				// First node of q is lower; e must come from q.
   482				__e = __q;
   483				__q = __q->_M_next;
   484				--__qsize;
   485			      }
   486	
   487			    // Add the next node to the merged list.
   488			    if (__tail)
   489			      __tail->_M_next = __e;
   490			    else
   491			      __list = __e;
   492			    __tail = __e;
   493			  }
   494	
   495			// Now p has stepped `insize' places along, and q has too.
   496			__p = __q;
   497		      }
   498		    __tail->_M_next = nullptr;
   499	
   500		    // If we have done only one merge, we're finished.
   501		    // Allow for nmerges == 0, the empty list case.
   502		    if (__nmerges <= 1)
   503		      {
   504			this->_M_impl._M_head._M_next = __list;
   505			return;
   506		      }
   507	
   508		    // Otherwise repeat, merging lists twice the size.
   509		    __insize *= 2;
   510		  }
   511	      }
   512	
   513	_GLIBCXX_END_NAMESPACE_CONTAINER
   514	_GLIBCXX_END_NAMESPACE_VERSION
   515	} // namespace std
   516	
   517	#endif /* _FORWARD_LIST_TCC */