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      1 // Safe sequence implementation  -*- C++ -*-
      2 
      3 // Copyright (C) 2003-2024 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 debug/safe_sequence.h
     26  *  This file is a GNU debug extension to the Standard C++ Library.
     27  */
     28 
     29 #ifndef _GLIBCXX_DEBUG_SAFE_SEQUENCE_H
     30 #define _GLIBCXX_DEBUG_SAFE_SEQUENCE_H 1
     31 
     32 #include <debug/assertions.h>
     33 #include <debug/macros.h>
     34 #include <debug/functions.h>
     35 #include <debug/safe_base.h>
     36 
     37 namespace __gnu_debug
     38 {
     39   /** A simple function object that returns true if the passed-in
     40    *  value is not equal to the stored value. It saves typing over
     41    *  using both bind1st and not_equal.
     42    */
     43   template<typename _Type>
     44     class _Not_equal_to
     45     {
     46       _Type __value;
     47 
     48     public:
     49       explicit _Not_equal_to(const _Type& __v) : __value(__v) { }
     50 
     51       bool
     52       operator()(const _Type& __x) const
     53       { return __value != __x; }
     54     };
     55 
     56   /** A simple function object that returns true if the passed-in
     57    *  value is equal to the stored value. */
     58   template <typename _Type>
     59     class _Equal_to
     60     {
     61       _Type __value;
     62 
     63     public:
     64       explicit _Equal_to(const _Type& __v) : __value(__v) { }
     65 
     66       bool
     67       operator()(const _Type& __x) const
     68       { return __value == __x; }
     69     };
     70 
     71   /** A function object that returns true when the given random access
     72       iterator is at least @c n steps away from the given iterator. */
     73   template<typename _Iterator>
     74     class _After_nth_from
     75     {
     76       typedef typename std::iterator_traits<_Iterator>::difference_type
     77       difference_type;
     78 
     79       _Iterator _M_base;
     80       difference_type _M_n;
     81 
     82     public:
     83       _After_nth_from(const difference_type& __n, const _Iterator& __base)
     84       : _M_base(__base), _M_n(__n) { }
     85 
     86       bool
     87       operator()(const _Iterator& __x) const
     88       { return __x - _M_base >= _M_n; }
     89     };
     90 
     91   /**
     92    * @brief Base class for constructing a @a safe sequence type that
     93    * tracks iterators that reference it.
     94    *
     95    * The class template %_Safe_sequence simplifies the construction of
     96    * @a safe sequences that track the iterators that reference the
     97    * sequence, so that the iterators are notified of changes in the
     98    * sequence that may affect their operation, e.g., if the container
     99    * invalidates its iterators or is destructed. This class template
    100    * may only be used by deriving from it and passing the name of the
    101    * derived class as its template parameter via the curiously
    102    * recurring template pattern. The derived class must have @c
    103    * iterator and @c const_iterator types that are instantiations of
    104    * class template _Safe_iterator for this sequence. Iterators will
    105    * then be tracked automatically.
    106    */
    107   template<typename _Sequence>
    108     class _Safe_sequence : public _Safe_sequence_base
    109     {
    110     public:
    111       /** Invalidates all iterators @c x that reference this sequence,
    112 	  are not singular, and for which @c __pred(x) returns @c
    113 	  true. @c __pred will be invoked with the normal iterators nested
    114 	  in the safe ones. */
    115       template<typename _Predicate>
    116 	void
    117 	_M_invalidate_if(_Predicate __pred);
    118 
    119       /** Transfers all iterators @c x that reference @c from sequence,
    120 	  are not singular, and for which @c __pred(x) returns @c
    121 	  true. @c __pred will be invoked with the normal iterators nested
    122 	  in the safe ones. */
    123       template<typename _Predicate>
    124 	void
    125 	_M_transfer_from_if(_Safe_sequence& __from, _Predicate __pred);
    126     };
    127 
    128   /// Like _Safe_sequence but with a special _M_invalidate_all implementation
    129   /// not invalidating past-the-end iterators. Used by node based sequence.
    130   template<typename _Sequence>
    131     class _Safe_node_sequence
    132     : public _Safe_sequence<_Sequence>
    133     {
    134     protected:
    135       void
    136       _M_invalidate_all()
    137       {
    138 	typedef typename _Sequence::const_iterator _Const_iterator;
    139 	typedef typename _Const_iterator::iterator_type _Base_const_iterator;
    140 	typedef __gnu_debug::_Not_equal_to<_Base_const_iterator> _Not_equal;
    141 	const _Sequence& __seq = *static_cast<_Sequence*>(this);
    142 	this->_M_invalidate_if(_Not_equal(__seq._M_base().end()));
    143       }
    144     };
    145 
    146 } // namespace __gnu_debug
    147 
    148 #include <debug/safe_sequence.tcc>
    149 
    150 #endif
    151