libstdc++
safe_iterator.tcc
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00001 // Debugging iterator implementation (out of line) -*- C++ -*-
00002 
00003 // Copyright (C) 2003-2015 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /** @file debug/safe_iterator.tcc
00026  *  This file is a GNU debug extension to the Standard C++ Library.
00027  */
00028 
00029 #ifndef _GLIBCXX_DEBUG_SAFE_ITERATOR_TCC
00030 #define _GLIBCXX_DEBUG_SAFE_ITERATOR_TCC 1
00031 
00032 namespace __gnu_debug
00033 {
00034   template<typename _Iterator, typename _Sequence>
00035     bool
00036     _Safe_iterator<_Iterator, _Sequence>::
00037     _M_can_advance(const difference_type& __n) const
00038     {
00039       if (this->_M_singular())
00040         return false;
00041       if (__n == 0)
00042         return true;
00043       if (__n < 0)
00044         {
00045           std::pair<difference_type, _Distance_precision> __dist =
00046             __get_distance(_M_get_sequence()->_M_base().begin(), base());
00047           bool __ok =  ((__dist.second == __dp_exact && __dist.first >= -__n)
00048                         || (__dist.second != __dp_exact && __dist.first > 0));
00049           return __ok;
00050         }
00051       else
00052         {
00053           std::pair<difference_type, _Distance_precision> __dist =
00054             __get_distance(base(), _M_get_sequence()->_M_base().end());
00055           bool __ok = ((__dist.second == __dp_exact && __dist.first >= __n)
00056                        || (__dist.second != __dp_exact && __dist.first > 0));
00057           return __ok;
00058         }
00059     }
00060 
00061   template<typename _Iterator, typename _Sequence>
00062     bool
00063     _Safe_iterator<_Iterator, _Sequence>::
00064     _M_valid_range(const _Safe_iterator& __rhs) const
00065     {
00066       if (!_M_can_compare(__rhs))
00067         return false;
00068 
00069       /* Determine if we can order the iterators without the help of
00070          the container */
00071       std::pair<difference_type, _Distance_precision> __dist =
00072         __get_distance(base(), __rhs.base());
00073       switch (__dist.second) {
00074       case __dp_equality:
00075         if (__dist.first == 0)
00076           return true;
00077         break;
00078 
00079       case __dp_sign:
00080       case __dp_exact:
00081         return __dist.first >= 0;
00082       }
00083 
00084       /* We can only test for equality, but check if one of the
00085          iterators is at an extreme. */
00086       /* Optim for classic [begin, it) or [it, end) ranges, limit checks
00087        * when code is valid.  Note, for the special case of forward_list,
00088        * before_begin replaces the role of begin.  */ 
00089       if (_M_is_beginnest() || __rhs._M_is_end())
00090         return true;
00091       if (_M_is_end() || __rhs._M_is_beginnest())
00092         return false;
00093 
00094       // Assume that this is a valid range; we can't check anything else
00095       return true;
00096     }
00097 } // namespace __gnu_debug
00098 
00099 #endif
00100