functions.h

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// Debugging support implementation -*- C++ -*-

// Copyright (C) 2003-2014 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/functions.h
 *  This file is a GNU debug extension to the Standard C++ Library.
 */

#ifndef _GLIBCXX_DEBUG_FUNCTIONS_H
#define _GLIBCXX_DEBUG_FUNCTIONS_H 1

#include <bits/c++config.h>
#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/move.h>                    // for __addressof and addressof
#if __cplusplus >= 201103L
# include <bits/stl_function.h>       // for less and greater_equal
# include <type_traits>           // for is_lvalue_reference and __and_
#endif
#include <debug/formatter.h>

namespace __gnu_debug
{
  template<typename _Iterator, typename _Sequence>
    class _Safe_iterator;

  template<typename _Iterator, typename _Sequence>
    class _Safe_local_iterator;

  template<typename _Sequence>
    struct _Insert_range_from_self_is_safe
    { enum { __value = 0 }; };

  // 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>
    inline bool
    __check_singular(const _Iterator& __x)
    { return __check_singular_aux(&__x); }

  /** Non-NULL pointers are nonsingular. */
  template<typename _Tp>
    inline bool
    __check_singular(const _Tp* __ptr)
    { return __ptr == 0; }

  /** Assume that some arbitrary iterator is dereferenceable, because we
      can't prove that it isn't. */
  template<typename _Iterator>
    inline bool
    __check_dereferenceable(const _Iterator&)
    { return true; }

  /** Non-NULL pointers are dereferenceable. */
  template<typename _Tp>
    inline bool
    __check_dereferenceable(const _Tp* __ptr)
    { return __ptr; }

  /** Safe iterators know if they are dereferenceable. */
  template<typename _Iterator, typename _Sequence>
    inline bool
    __check_dereferenceable(const _Safe_iterator<_Iterator, _Sequence>& __x)
    { return __x._M_dereferenceable(); }

  /** Safe local iterators know if they are dereferenceable. */
  template<typename _Iterator, typename _Sequence>
    inline bool
    __check_dereferenceable(const _Safe_local_iterator<_Iterator,
                               _Sequence>& __x)
    { return __x._M_dereferenceable(); }

  /** If the distance between two random access iterators is
   *  nonnegative, assume the range is valid.
  */
  template<typename _RandomAccessIterator>
    inline bool
    __valid_range_aux2(const _RandomAccessIterator& __first,
               const _RandomAccessIterator& __last,
               std::random_access_iterator_tag)
    { return __last - __first >= 0; }

  /** Can't test for a valid range with input iterators, because
   *  iteration may be destructive. So we just assume that the range
   *  is valid.
  */
  template<typename _InputIterator>
    inline bool
    __valid_range_aux2(const _InputIterator&, const _InputIterator&,
               std::input_iterator_tag)
    { return true; }

  /** 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>
    inline bool
    __valid_range_aux(const _Integral&, const _Integral&, std::__true_type)
    { return true; }

  /** We have iterators, so figure out what kind of iterators that are
   *  to see if we can check the range ahead of time.
  */
  template<typename _InputIterator>
    inline bool
    __valid_range_aux(const _InputIterator& __first,
              const _InputIterator& __last, std::__false_type)
    { return __valid_range_aux2(__first, __last,
                std::__iterator_category(__first)); }

  /** 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>
    inline bool
    __valid_range(const _InputIterator& __first, const _InputIterator& __last)
    {
      typedef typename std::__is_integer<_InputIterator>::__type _Integral;
      return __valid_range_aux(__first, __last, _Integral());
    }

  /** Safe iterators know how to check if they form a valid range. */
  template<typename _Iterator, typename _Sequence>
    inline bool
    __valid_range(const _Safe_iterator<_Iterator, _Sequence>& __first,
          const _Safe_iterator<_Iterator, _Sequence>& __last)
    { return __first._M_valid_range(__last); }

  /** Safe local iterators know how to check if they form a valid range. */
  template<typename _Iterator, typename _Sequence>
    inline bool
    __valid_range(const _Safe_local_iterator<_Iterator, _Sequence>& __first,
          const _Safe_local_iterator<_Iterator, _Sequence>& __last)
    { return __first._M_valid_range(__last); }

  /* Checks that [first, last) is a valid range, and then returns
   * __first. This routine is useful when we can't use a separate
   * assertion statement because, e.g., we are in a constructor.
  */
  template<typename _InputIterator>
    inline _InputIterator
    __check_valid_range(const _InputIterator& __first,
            const _InputIterator& __last
            __attribute__((__unused__)))
    {
      __glibcxx_check_valid_range(__first, __last);
      return __first;
    }

#if __cplusplus >= 201103L
  // Default implementation.
  template<typename _Iterator, typename _Sequence>
    inline bool
    __foreign_iterator_aux4(const _Safe_iterator<_Iterator, _Sequence>& __it,
                typename _Sequence::const_pointer __begin,
                typename _Sequence::const_pointer __other)
    {
      typedef typename _Sequence::const_pointer _PointerType;
      constexpr std::less<_PointerType> __l{};

      return (__l(__other, __begin)
          || __l(std::addressof(*(__it._M_get_sequence()->_M_base().end()
                      - 1)), __other));
    }

  // Fallback when address type cannot be implicitely casted to sequence
  // const_pointer.
  template<typename _Iterator, typename _Sequence,
       typename _InputIterator>
    inline bool
    __foreign_iterator_aux4(const _Safe_iterator<_Iterator, _Sequence>&,
                _InputIterator, ...)
    { return true; }

  template<typename _Iterator, typename _Sequence, typename _InputIterator>
    inline bool
    __foreign_iterator_aux3(const _Safe_iterator<_Iterator, _Sequence>& __it,
                _InputIterator __other,
                std::true_type)
    {
      // Only containers with all elements in contiguous memory can have their
      // elements passed through pointers.
      // Arithmetics is here just to make sure we are not dereferencing
      // past-the-end iterator.
      if (__it._M_get_sequence()->_M_base().begin()
      != __it._M_get_sequence()->_M_base().end())
    if (std::addressof(*(__it._M_get_sequence()->_M_base().end() - 1))
        - std::addressof(*(__it._M_get_sequence()->_M_base().begin()))
        == __it._M_get_sequence()->size() - 1)
      return (__foreign_iterator_aux4
          (__it,
           std::addressof(*(__it._M_get_sequence()->_M_base().begin())),
           std::addressof(*__other)));
      return true;
    }
               
  /* Fallback overload for which we can't say, assume it is valid. */
  template<typename _Iterator, typename _Sequence, typename _InputIterator>
    inline bool
    __foreign_iterator_aux3(const _Safe_iterator<_Iterator, _Sequence>& __it,
                _InputIterator __other,
                std::false_type)
    { return true; }
#endif

  /** Checks that iterators do not belong to the same sequence. */
  template<typename _Iterator, typename _Sequence, typename _OtherIterator>
    inline bool
    __foreign_iterator_aux2(const _Safe_iterator<_Iterator, _Sequence>& __it,
        const _Safe_iterator<_OtherIterator, _Sequence>& __other,
        std::input_iterator_tag)
    { return __it._M_get_sequence() != __other._M_get_sequence(); }
               
#if __cplusplus >= 201103L
  /* This overload detects when passing pointers to the contained elements
     rather than using iterators.
   */
  template<typename _Iterator, typename _Sequence, typename _InputIterator>
    inline bool
    __foreign_iterator_aux2(const _Safe_iterator<_Iterator, _Sequence>& __it,
                _InputIterator __other,
                std::random_access_iterator_tag)
    {
      typedef typename _Sequence::const_iterator _ItType;
      typedef typename std::iterator_traits<_ItType>::reference _Ref;
      return __foreign_iterator_aux3(__it, __other,
                     std::is_lvalue_reference<_Ref>());
    }
#endif
               
  /* Fallback overload for which we can't say, assume it is valid. */
  template<typename _Iterator, typename _Sequence, typename _InputIterator>
    inline bool
    __foreign_iterator_aux2(const _Safe_iterator<_Iterator, _Sequence>&,
               _InputIterator,
               std::input_iterator_tag)
    { return true; }
               
  template<typename _Iterator, typename _Sequence,
       typename _Integral>
    inline bool
    __foreign_iterator_aux(const _Safe_iterator<_Iterator, _Sequence>& __it,
               _Integral __other,
               std::__true_type)
    { return true; }

  template<typename _Iterator, typename _Sequence,
       typename _InputIterator>
    inline bool
    __foreign_iterator_aux(const _Safe_iterator<_Iterator, _Sequence>& __it,
               _InputIterator __other,
               std::__false_type)
    {
      return (_Insert_range_from_self_is_safe<_Sequence>::__value
          || __foreign_iterator_aux2(__it, __other,
                     std::__iterator_category(__it)));
    }

  template<typename _Iterator, typename _Sequence,
       typename _InputIterator>
    inline bool
    __foreign_iterator(const _Safe_iterator<_Iterator, _Sequence>& __it,
               _InputIterator __other)
    {
      typedef typename std::__is_integer<_InputIterator>::__type _Integral;
      return __foreign_iterator_aux(__it, __other, _Integral());
    }

  /** Checks that __s is non-NULL or __n == 0, and then returns __s. */
  template<typename _CharT, typename _Integer>
    inline const _CharT*
    __check_string(const _CharT* __s,
           const _Integer& __n __attribute__((__unused__)))
    {
#ifdef _GLIBCXX_DEBUG_PEDANTIC
      __glibcxx_assert(__s != 0 || __n == 0);
#endif
      return __s;
    }

  /** Checks that __s is non-NULL and then returns __s. */
  template<typename _CharT>
    inline const _CharT*
    __check_string(const _CharT* __s)
    {
#ifdef _GLIBCXX_DEBUG_PEDANTIC
      __glibcxx_assert(__s != 0);
#endif
      return __s;
    }

  // Can't check if an input iterator sequence is sorted, because we
  // can't step through the sequence.
  template<typename _InputIterator>
    inline bool
    __check_sorted_aux(const _InputIterator&, const _InputIterator&,
                       std::input_iterator_tag)
    { return true; }

  // Can verify if a forward iterator sequence is in fact sorted using
  // std::__is_sorted
  template<typename _ForwardIterator>
    inline bool
    __check_sorted_aux(_ForwardIterator __first, _ForwardIterator __last,
                       std::forward_iterator_tag)
    {
      if (__first == __last)
        return true;

      _ForwardIterator __next = __first;
      for (++__next; __next != __last; __first = __next, ++__next)
        if (*__next < *__first)
          return false;

      return true;
    }

  // Can't check if an input iterator sequence is sorted, because we can't step
  // through the sequence.
  template<typename _InputIterator, typename _Predicate>
    inline bool
    __check_sorted_aux(const _InputIterator&, const _InputIterator&,
                       _Predicate, std::input_iterator_tag)
    { return true; }

  // Can verify if a forward iterator sequence is in fact sorted using
  // std::__is_sorted
  template<typename _ForwardIterator, typename _Predicate>
    inline bool
    __check_sorted_aux(_ForwardIterator __first, _ForwardIterator __last,
                       _Predicate __pred, std::forward_iterator_tag)
    {
      if (__first == __last)
        return true;

      _ForwardIterator __next = __first;
      for (++__next; __next != __last; __first = __next, ++__next)
        if (__pred(*__next, *__first))
          return false;

      return true;
    }

  // Determine if a sequence is sorted.
  template<typename _InputIterator>
    inline bool
    __check_sorted(const _InputIterator& __first, const _InputIterator& __last)
    {
      // Verify that the < operator for elements in the sequence is a
      // StrictWeakOrdering by checking that it is irreflexive.
      __glibcxx_assert(__first == __last || !(*__first < *__first));

      return __check_sorted_aux(__first, __last,
                std::__iterator_category(__first));
    }

  template<typename _InputIterator, typename _Predicate>
    inline bool
    __check_sorted(const _InputIterator& __first, const _InputIterator& __last,
                   _Predicate __pred)
    {
      // Verify that the predicate is StrictWeakOrdering by checking that it
      // is irreflexive.
      __glibcxx_assert(__first == __last || !__pred(*__first, *__first));

      return __check_sorted_aux(__first, __last, __pred,
                std::__iterator_category(__first));
    }

  template<typename _InputIterator>
    inline bool
    __check_sorted_set_aux(const _InputIterator& __first,
               const _InputIterator& __last,
               std::__true_type)
    { return __check_sorted(__first, __last); }

  template<typename _InputIterator>
    inline bool
    __check_sorted_set_aux(const _InputIterator&,
               const _InputIterator&,
               std::__false_type)
    { return true; }

  template<typename _InputIterator, typename _Predicate>
    inline bool
    __check_sorted_set_aux(const _InputIterator& __first,
               const _InputIterator& __last,
               _Predicate __pred, std::__true_type)
    { return __check_sorted(__first, __last, __pred); }

  template<typename _InputIterator, typename _Predicate>
    inline bool
    __check_sorted_set_aux(const _InputIterator&,
               const _InputIterator&, _Predicate,
               std::__false_type)
    { return true; }

  // ... special variant used in std::merge, std::includes, std::set_*.
  template<typename _InputIterator1, typename _InputIterator2>
    inline bool
    __check_sorted_set(const _InputIterator1& __first,
               const _InputIterator1& __last,
               const _InputIterator2&)
    {
      typedef typename std::iterator_traits<_InputIterator1>::value_type
    _ValueType1;
      typedef typename std::iterator_traits<_InputIterator2>::value_type
    _ValueType2;

      typedef typename std::__are_same<_ValueType1, _ValueType2>::__type
    _SameType;
      return __check_sorted_set_aux(__first, __last, _SameType());
    }

  template<typename _InputIterator1, typename _InputIterator2,
       typename _Predicate>
    inline bool
    __check_sorted_set(const _InputIterator1& __first,
               const _InputIterator1& __last,
               const _InputIterator2&, _Predicate __pred)
    {
      typedef typename std::iterator_traits<_InputIterator1>::value_type
    _ValueType1;
      typedef typename std::iterator_traits<_InputIterator2>::value_type
    _ValueType2;

      typedef typename std::__are_same<_ValueType1, _ValueType2>::__type
    _SameType;
      return __check_sorted_set_aux(__first, __last, __pred, _SameType());
   }

  // _GLIBCXX_RESOLVE_LIB_DEFECTS
  // 270. Binary search requirements overly strict
  // Determine if a sequence is partitioned w.r.t. this element.
  template<typename _ForwardIterator, typename _Tp>
    inline bool
    __check_partitioned_lower(_ForwardIterator __first,
                  _ForwardIterator __last, const _Tp& __value)
    {
      while (__first != __last && *__first < __value)
    ++__first;
      if (__first != __last)
    {
      ++__first;
      while (__first != __last && !(*__first < __value))
        ++__first;
    }
      return __first == __last;
    }

  template<typename _ForwardIterator, typename _Tp>
    inline bool
    __check_partitioned_upper(_ForwardIterator __first,
                  _ForwardIterator __last, const _Tp& __value)
    {
      while (__first != __last && !(__value < *__first))
    ++__first;
      if (__first != __last)
    {
      ++__first;
      while (__first != __last && __value < *__first)
        ++__first;
    }
      return __first == __last;
    }

  // Determine if a sequence is partitioned w.r.t. this element.
  template<typename _ForwardIterator, typename _Tp, typename _Pred>
    inline bool
    __check_partitioned_lower(_ForwardIterator __first,
                  _ForwardIterator __last, const _Tp& __value,
                  _Pred __pred)
    {
      while (__first != __last && bool(__pred(*__first, __value)))
    ++__first;
      if (__first != __last)
    {
      ++__first;
      while (__first != __last && !bool(__pred(*__first, __value)))
        ++__first;
    }
      return __first == __last;
    }

  template<typename _ForwardIterator, typename _Tp, typename _Pred>
    inline bool
    __check_partitioned_upper(_ForwardIterator __first,
                  _ForwardIterator __last, const _Tp& __value,
                  _Pred __pred)
    {
      while (__first != __last && !bool(__pred(__value, *__first)))
    ++__first;
      if (__first != __last)
    {
      ++__first;
      while (__first != __last && bool(__pred(__value, *__first)))
        ++__first;
    }
      return __first == __last;
    }

  // Helper struct to detect random access safe iterators.
  template<typename _Iterator>
    struct __is_safe_random_iterator
    {
      enum { __value = 0 };
      typedef std::__false_type __type;
    };

  template<typename _Iterator, typename _Sequence>
    struct __is_safe_random_iterator<_Safe_iterator<_Iterator, _Sequence> >
    : std::__are_same<std::random_access_iterator_tag,
                      typename std::iterator_traits<_Iterator>::
              iterator_category>
    { };

  template<typename _Iterator>
    struct _Siter_base
    : std::_Iter_base<_Iterator, __is_safe_random_iterator<_Iterator>::__value>
    { };

  /** 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>
    inline typename _Siter_base<_Iterator>::iterator_type
    __base(_Iterator __it)
    { return _Siter_base<_Iterator>::_S_base(__it); }
} // namespace __gnu_debug

#endif