helper_functions.h
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// Debugging support implementation -*- C++ -*-
// Copyright (C) 2003-2021 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 debug/helper_functions.h
* This file is a GNU debug extension to the Standard C++ Library.
*/
#ifndef _GLIBCXX_DEBUG_HELPER_FUNCTIONS_H
#define _GLIBCXX_DEBUG_HELPER_FUNCTIONS_H 1
#include <bits/move.h> // for __addressof
#include <bits/stl_iterator_base_types.h> // for iterator_traits,
// categories and _Iter_base
#include <bits/cpp_type_traits.h> // for __is_integer
#include <bits/stl_pair.h> // for pair
namespace __gnu_debug
{
template<typename _Iterator, typename _Sequence, typename _Category>
class _Safe_iterator;
#if __cplusplus >= 201103L
template<typename _Iterator, typename _Sequence>
class _Safe_local_iterator;
#endif
/** The precision to which we can calculate the distance between
* two iterators.
*/
enum _Distance_precision
{
__dp_none, // Not even an iterator type
__dp_equality, //< Can compare iterator equality, only
__dp_sign, //< Can determine equality and ordering
__dp_sign_max_size, //< __dp_sign and gives max range size
__dp_exact //< Can determine distance precisely
};
template<typename _Iterator,
typename = typename std::__is_integer<_Iterator>::__type>
struct _Distance_traits
{
private:
typedef
typename std::iterator_traits<_Iterator>::difference_type _ItDiffType;
template<typename _DiffType,
typename = typename std::__is_void<_DiffType>::__type>
struct _DiffTraits
{ typedef _DiffType __type; };
template<typename _DiffType>
struct _DiffTraits<_DiffType, std::__true_type>
{ typedef std::ptrdiff_t __type; };
typedef typename _DiffTraits<_ItDiffType>::__type _DiffType;
public:
typedef std::pair<_DiffType, _Distance_precision> __type;
};
template<typename _Integral>
struct _Distance_traits<_Integral, std::__true_type>
{ typedef std::pair<std::ptrdiff_t, _Distance_precision> __type; };
/** Determine the distance between two iterators with some known
* precision.
*/
template<typename _Iterator>
_GLIBCXX_CONSTEXPR
inline typename _Distance_traits<_Iterator>::__type
__get_distance(_Iterator __lhs, _Iterator __rhs,
std::random_access_iterator_tag)
{ return std::make_pair(__rhs - __lhs, __dp_exact); }
template<typename _Iterator>
_GLIBCXX14_CONSTEXPR
inline typename _Distance_traits<_Iterator>::__type
__get_distance(_Iterator __lhs, _Iterator __rhs,
std::input_iterator_tag)
{
if (__lhs == __rhs)
return std::make_pair(0, __dp_exact);
return std::make_pair(1, __dp_equality);
}
template<typename _Iterator>
_GLIBCXX_CONSTEXPR
inline typename _Distance_traits<_Iterator>::__type
__get_distance(_Iterator __lhs, _Iterator __rhs)
{ return __get_distance(__lhs, __rhs, std::__iterator_category(__lhs)); }
// An arbitrary iterator pointer is not singular.
inline bool
__check_singular_aux(const void*) { return false; }
// We may have an iterator that derives from _Safe_iterator_base but isn't
// a _Safe_iterator.
template<typename _Iterator>
_GLIBCXX_CONSTEXPR
inline bool
__check_singular(_Iterator const& __x)
{
return
#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
__builtin_is_constant_evaluated() ? false :
#endif
__check_singular_aux(std::__addressof(__x));
}
/** Non-NULL pointers are nonsingular. */
template<typename _Tp>
_GLIBCXX_CONSTEXPR
inline bool
__check_singular(_Tp* const& __ptr)
{
return
#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
__builtin_is_constant_evaluated() ? false :
#endif
__ptr == 0;
}
/** We say that integral types for a valid range, and defer to other
* routines to realize what to do with integral types instead of
* iterators.
*/
template<typename _Integral>
_GLIBCXX_CONSTEXPR
inline bool
__valid_range_aux(_Integral, _Integral, std::__true_type)
{ return true; }
template<typename _Integral>
_GLIBCXX20_CONSTEXPR
inline bool
__valid_range_aux(_Integral, _Integral,
typename _Distance_traits<_Integral>::__type& __dist,
std::__true_type)
{
__dist = std::make_pair(0, __dp_none);
return true;
}
template<typename _InputIterator>
_GLIBCXX_CONSTEXPR
inline bool
__valid_range_aux(_InputIterator __first, _InputIterator __last,
std::input_iterator_tag)
{
return __first == __last
|| (!__check_singular(__first) && !__check_singular(__last));
}
template<typename _InputIterator>
_GLIBCXX_CONSTEXPR
inline bool
__valid_range_aux(_InputIterator __first, _InputIterator __last,
std::random_access_iterator_tag)
{
return
__valid_range_aux(__first, __last, std::input_iterator_tag())
&& __first <= __last;
}
/** We have iterators, so figure out what kind of iterators they are
* to see if we can check the range ahead of time.
*/
template<typename _InputIterator>
_GLIBCXX_CONSTEXPR
inline bool
__valid_range_aux(_InputIterator __first, _InputIterator __last,
std::__false_type)
{
return __valid_range_aux(__first, __last,
std::__iterator_category(__first));
}
template<typename _InputIterator>
_GLIBCXX20_CONSTEXPR
inline bool
__valid_range_aux(_InputIterator __first, _InputIterator __last,
typename _Distance_traits<_InputIterator>::__type& __dist,
std::__false_type)
{
if (!__valid_range_aux(__first, __last, std::input_iterator_tag()))
return false;
__dist = __get_distance(__first, __last);
switch (__dist.second)
{
case __dp_none:
break;
case __dp_equality:
if (__dist.first == 0)
return true;
break;
case __dp_sign:
case __dp_sign_max_size:
case __dp_exact:
return __dist.first >= 0;
}
// Can't tell so assume it is fine.
return true;
}
/** Don't know what these iterators are, or if they are even
* iterators (we may get an integral type for InputIterator), so
* see if they are integral and pass them on to the next phase
* otherwise.
*/
template<typename _InputIterator>
_GLIBCXX20_CONSTEXPR
inline bool
__valid_range(_InputIterator __first, _InputIterator __last,
typename _Distance_traits<_InputIterator>::__type& __dist)
{
typedef typename std::__is_integer<_InputIterator>::__type _Integral;
return __valid_range_aux(__first, __last, __dist, _Integral());
}
template<typename _Iterator, typename _Sequence, typename _Category>
bool
__valid_range(const _Safe_iterator<_Iterator, _Sequence, _Category>&,
const _Safe_iterator<_Iterator, _Sequence, _Category>&,
typename _Distance_traits<_Iterator>::__type&);
#if __cplusplus >= 201103L
template<typename _Iterator,typename _Sequence>
bool
__valid_range(const _Safe_local_iterator<_Iterator, _Sequence>&,
const _Safe_local_iterator<_Iterator, _Sequence>&,
typename _Distance_traits<_Iterator>::__type&);
#endif
template<typename _InputIterator>
_GLIBCXX14_CONSTEXPR
inline bool
__valid_range(_InputIterator __first, _InputIterator __last)
{
typedef typename std::__is_integer<_InputIterator>::__type _Integral;
return __valid_range_aux(__first, __last, _Integral());
}
template<typename _Iterator, typename _Sequence, typename _Category>
bool
__valid_range(const _Safe_iterator<_Iterator, _Sequence, _Category>&,
const _Safe_iterator<_Iterator, _Sequence, _Category>&);
#if __cplusplus >= 201103L
template<typename _Iterator, typename _Sequence>
bool
__valid_range(const _Safe_local_iterator<_Iterator, _Sequence>&,
const _Safe_local_iterator<_Iterator, _Sequence>&);
#endif
// Fallback method, always ok.
template<typename _InputIterator, typename _Size>
_GLIBCXX_CONSTEXPR
inline bool
__can_advance(_InputIterator, _Size)
{ return true; }
template<typename _Iterator, typename _Sequence, typename _Category,
typename _Size>
bool
__can_advance(const _Safe_iterator<_Iterator, _Sequence, _Category>&,
_Size);
template<typename _InputIterator, typename _Diff>
_GLIBCXX_CONSTEXPR
inline bool
__can_advance(_InputIterator, const std::pair<_Diff, _Distance_precision>&, int)
{ return true; }
template<typename _Iterator, typename _Sequence, typename _Category,
typename _Diff>
bool
__can_advance(const _Safe_iterator<_Iterator, _Sequence, _Category>&,
const std::pair<_Diff, _Distance_precision>&, int);
/** Helper function to extract base iterator of random access safe iterator
* in order to reduce performance impact of debug mode. Limited to random
* access iterator because it is the only category for which it is possible
* to check for correct iterators order in the __valid_range function
* thanks to the < operator.
*/
template<typename _Iterator>
_GLIBCXX_CONSTEXPR
inline _Iterator
__base(_Iterator __it)
{ return __it; }
#if __cplusplus < 201103L
template<typename _Iterator>
struct _Unsafe_type
{ typedef _Iterator _Type; };
#endif
/* Remove debug mode safe iterator layer, if any. */
template<typename _Iterator>
inline _Iterator
__unsafe(_Iterator __it)
{ return __it; }
}
#endif
cpp_type_traits.h
move.h
stl_iterator_base_types.h
stl_pair.h
std::__addressof
constexpr _Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition: move.h:49
std::__iterator_category
constexpr iterator_traits< _Iter >::iterator_category __iterator_category(const _Iter &)
Definition: stl_iterator_base_types.h:238
std
ISO C++ entities toplevel namespace is std.
__gnu_debug
GNU debug classes for public use.
__gnu_debug::__get_distance
constexpr _Distance_traits< _Iterator >::__type __get_distance(_Iterator __lhs, _Iterator __rhs, std::random_access_iterator_tag)
Definition: helper_functions.h:94
__gnu_debug::_Distance_precision
_Distance_precision
Definition: helper_functions.h:53
__gnu_debug::__valid_range_aux
constexpr bool __valid_range_aux(_Integral, _Integral, std::__true_type)
Definition: helper_functions.h:154
__gnu_debug::__valid_range
constexpr bool __valid_range(_InputIterator __first, _InputIterator __last, typename _Distance_traits< _InputIterator >::__type &__dist)
Definition: helper_functions.h:239
__gnu_debug::__base
constexpr _Iterator __base(_Iterator __it)
Definition: helper_functions.h:315
std::iterator_traits
Traits class for iterators.
Definition: stl_iterator_base_types.h:178
std::input_iterator_tag
Marking input iterators.
Definition: stl_iterator_base_types.h:93
std::random_access_iterator_tag
Random-access iterators support a superset of bidirectional iterator operations.
Definition: stl_iterator_base_types.h:107
std::pair
Struct holding two objects of arbitrary type.
Definition: stl_pair.h:213