Fix PR52822 (stable_partition move-assigns object to itself) by scanning for...
Fix PR52822 (stable_partition move-assigns object to itself) by scanning for the first value that doesn't match the predicate before starting to rearrange values. 2012-04-03 Jeffrey Yasskin <jyasskin@google.com> PR libstdc++/52822 * include/bits/stl_algo.h (__find_if_not): Expose in C++98 mode. (__find_if_not_n): Like __find_if_not, but works on and updates a counted range instead of a bounded range. (stable_partition): Guarantee !__pred(*__first) in call to __stable_partition_adaptive() or __inplace_stable_partition(). (__stable_partition_adaptive): Use new precondition to avoid moving/copying objects onto themselves. Guarantee new precondition to recursive calls. (__inplace_stable_partition): Use new precondition to simplify base case, remove __last parameter. Guarantee new precondition to recursive calls. * testsuite/25_algorithms/stable_partition/moveable.cc (test02): Test a sequence that starts with a value matching the predicate. * testsuite/25_algorithms/stable_partition/pr52822.cc: Test vectors, which have a destructive self-move-assignment. From-SVN: r186391
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Jeffrey Yasskin
Jeffrey Yasskin
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@ -1,3 +1,22 @@
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2012-04-12 Jeffrey Yasskin <jyasskin@google.com>
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PR libstdc++/52822
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* include/bits/stl_algo.h (__find_if_not): Expose in C++98 mode.
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(__find_if_not_n): Like __find_if_not, but works on and updates a
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counted range instead of a bounded range.
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(stable_partition): Guarantee !__pred(*__first) in call to
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__stable_partition_adaptive() or __inplace_stable_partition().
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(__stable_partition_adaptive): Use new precondition to avoid
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moving/copying objects onto themselves. Guarantee new
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precondition to recursive calls.
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(__inplace_stable_partition): Use new precondition to simplify
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base case, remove __last parameter. Guarantee new precondition to
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recursive calls.
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* testsuite/25_algorithms/stable_partition/moveable.cc (test02):
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Test a sequence that starts with a value matching the predicate.
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* testsuite/25_algorithms/stable_partition/pr52822.cc: Test
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vectors, which have a destructive self-move-assignment.
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2012-04-12 Andreas Schwab <schwab@linux-m68k.org>
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* testsuite/Makefile.am (check_DEJAGNUnormal0): Run
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@ -244,7 +244,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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}
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}
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#ifdef __GXX_EXPERIMENTAL_CXX0X__
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/// This is an overload used by find_if_not() for the Input Iterator case.
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template<typename _InputIterator, typename _Predicate>
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inline _InputIterator
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@ -303,7 +302,29 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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return __last;
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}
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}
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#endif
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/// Provided for stable_partition to use.
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template<typename _InputIterator, typename _Predicate>
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inline _InputIterator
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__find_if_not(_InputIterator __first, _InputIterator __last,
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_Predicate __pred)
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{
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return std::__find_if_not(__first, __last, __pred,
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std::__iterator_category(__first));
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}
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/// Like find_if_not(), but uses and updates a count of the
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/// remaining range length instead of comparing against an end
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/// iterator.
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template<typename _InputIterator, typename _Predicate, typename _Distance>
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_InputIterator
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__find_if_not_n(_InputIterator __first, _Distance& __len, _Predicate __pred)
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{
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for (; __len; --__len, ++__first)
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if (!bool(__pred(*__first)))
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break;
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return __first;
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}
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// set_difference
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// set_intersection
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@ -789,8 +810,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
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typename iterator_traits<_InputIterator>::value_type>)
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__glibcxx_requires_valid_range(__first, __last);
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return std::__find_if_not(__first, __last, __pred,
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std::__iterator_category(__first));
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return std::__find_if_not(__first, __last, __pred);
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}
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/**
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@ -1784,30 +1804,39 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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// partition
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/// This is a helper function...
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/// Requires __len != 0 and !__pred(*__first),
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/// same as __stable_partition_adaptive.
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template<typename _ForwardIterator, typename _Predicate, typename _Distance>
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_ForwardIterator
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__inplace_stable_partition(_ForwardIterator __first,
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_ForwardIterator __last,
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_Predicate __pred, _Distance __len)
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{
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if (__len == 1)
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return __pred(*__first) ? __last : __first;
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return __first;
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_ForwardIterator __middle = __first;
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std::advance(__middle, __len / 2);
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_ForwardIterator __begin = std::__inplace_stable_partition(__first,
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__middle,
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__pred,
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__len / 2);
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_ForwardIterator __end = std::__inplace_stable_partition(__middle, __last,
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__pred,
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__len
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- __len / 2);
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std::rotate(__begin, __middle, __end);
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std::advance(__begin, std::distance(__middle, __end));
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return __begin;
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_ForwardIterator __left_split =
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std::__inplace_stable_partition(__first, __pred, __len / 2);
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// Advance past true-predicate values to satisfy this
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// function's preconditions.
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_Distance __right_len = __len - __len / 2;
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_ForwardIterator __right_split =
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std::__find_if_not_n(__middle, __right_len, __pred);
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if (__right_len)
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__right_split = std::__inplace_stable_partition(__middle,
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__pred,
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__right_len);
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std::rotate(__left_split, __middle, __right_split);
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std::advance(__left_split, std::distance(__middle, __right_split));
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return __left_split;
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}
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/// This is a helper function...
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/// Requires __first != __last and !__pred(*__first)
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/// and __len == distance(__first, __last).
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///
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/// !__pred(*__first) allows us to guarantee that we don't
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/// move-assign an element onto itself.
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template<typename _ForwardIterator, typename _Pointer, typename _Predicate,
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typename _Distance>
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_ForwardIterator
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@ -1821,6 +1850,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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{
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_ForwardIterator __result1 = __first;
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_Pointer __result2 = __buffer;
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// The precondition guarantees that !__pred(*__first), so
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// move that element to the buffer before starting the loop.
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// This ensures that we only call __pred once per element.
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*__result2 = _GLIBCXX_MOVE(*__first);
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++__result2;
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++__first;
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for (; __first != __last; ++__first)
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if (__pred(*__first))
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{
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@ -1839,17 +1874,23 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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{
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_ForwardIterator __middle = __first;
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std::advance(__middle, __len / 2);
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_ForwardIterator __begin =
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_ForwardIterator __left_split =
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std::__stable_partition_adaptive(__first, __middle, __pred,
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__len / 2, __buffer,
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__buffer_size);
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_ForwardIterator __end =
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std::__stable_partition_adaptive(__middle, __last, __pred,
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__len - __len / 2,
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__buffer, __buffer_size);
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std::rotate(__begin, __middle, __end);
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std::advance(__begin, std::distance(__middle, __end));
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return __begin;
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// Advance past true-predicate values to satisfy this
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// function's preconditions.
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_Distance __right_len = __len - __len / 2;
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_ForwardIterator __right_split =
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std::__find_if_not_n(__middle, __right_len, __pred);
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if (__right_len)
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__right_split =
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std::__stable_partition_adaptive(__right_split, __last, __pred,
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__right_len,
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__buffer, __buffer_size);
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std::rotate(__left_split, __middle, __right_split);
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std::advance(__left_split, std::distance(__middle, __right_split));
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return __left_split;
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}
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}
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@ -1882,6 +1923,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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typename iterator_traits<_ForwardIterator>::value_type>)
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__glibcxx_requires_valid_range(__first, __last);
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__first = std::__find_if_not(__first, __last, __pred);
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if (__first == __last)
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return __first;
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else
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@ -1901,7 +1944,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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_DistanceType(__buf.size()));
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else
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return
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std::__inplace_stable_partition(__first, __last, __pred,
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std::__inplace_stable_partition(__first, __pred,
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_DistanceType(__buf.requested_size()));
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}
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}
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@ -35,6 +35,11 @@ const int A[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17};
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const int B[] = {2, 4, 6, 8, 10, 12, 14, 16, 1, 3, 5, 7, 9, 11, 13, 15, 17};
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const int N = sizeof(A) / sizeof(int);
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// Check that starting with a true predicate works too. (PR52822)
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const int A2[] = {2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17};
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const int B2[] = {2, 4, 6, 8, 10, 12, 14, 16, 3, 5, 7, 9, 11, 13, 15, 17};
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const int N2 = sizeof(A2) / sizeof(int);
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struct Pred
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{
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bool
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@ -42,7 +47,7 @@ struct Pred
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{ return (x.val % 2) == 0; }
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};
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// 25.2.12 stable_partition()
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// 25.2.12 stable_partition(), starting with a false predicate.
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void
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test01()
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{
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@ -56,9 +61,24 @@ test01()
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VERIFY( std::equal(s1, s1 + N, B) );
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}
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// 25.2.12 stable_partition(), starting with a true predicate.
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void
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test02()
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{
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bool test __attribute__((unused)) = true;
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rvalstruct s1[N2];
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std::copy(A2, A2 + N2, s1);
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Container con(s1, s1 + N2);
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std::stable_partition(con.begin(), con.end(), Pred());
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VERIFY( std::equal(s1, s1 + N2, B2) );
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}
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int
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main()
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{
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test01();
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test02();
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return 0;
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}
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@ -0,0 +1,43 @@
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// { dg-options "-std=gnu++0x" }
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// Copyright (C) 2012 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without Pred the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING3. If not see
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// <http://www.gnu.org/licenses/>.
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// 25.2.12 [lib.alg.partitions] Partitions.
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#include <algorithm>
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#include <vector>
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#include <testsuite_hooks.h>
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bool true_vector_pred(const std::vector<int>&) { return true; }
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void
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test01()
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{
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std::vector<std::vector<int> > v(1);
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v[0].push_back(7);
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VERIFY( v[0].size() == 1 );
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std::stable_partition(v.begin(), v.end(), &true_vector_pred);
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VERIFY( v[0].size() == 1 );
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}
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int
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main()
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{
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test01();
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return 0;
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}
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