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Fixed bug in random_shuffle to avoid swapping with self 

llvm-svn: 117098
This commit is contained in:
Howard Hinnant 2010-10-22 15:26:39 +00:00
parent 412c362d9e
commit 007b26be68
1 changed files with 14 additions and 3 deletions
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17
libcxx/include/algorithm
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@ -2686,7 +2686,11 @@ random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last)
_D __uid; _D __uid;
__rs_default __g = __rs_get(); __rs_default __g = __rs_get();
for (--__last, --__d; __first < __last; ++__first, --__d) for (--__last, --__d; __first < __last; ++__first, --__d)
swap(*__first, *(__first + __uid(__g, _P(0, __d)))); {
difference_type __i = __uid(__g, _P(0, __d));
if (__i != difference_type(0))
swap(*__first, *(__first + __i));
}
} }
} }
@ -2704,7 +2708,10 @@ random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
if (__d > 1) if (__d > 1)
{ {
for (--__last; __first < __last; ++__first, --__d) for (--__last; __first < __last; ++__first, --__d)
swap(*__first, *(__first + __rand(__d))); {
difference_type __i = __rand(__d);
swap(*__first, *(__first + __i));
}
} }
} }
@ -2720,7 +2727,11 @@ template<class _RandomAccessIterator, class _UniformRandomNumberGenerator>
{ {
_D __uid; _D __uid;
for (--__last, --__d; __first < __last; ++__first, --__d) for (--__last, --__d; __first < __last; ++__first, --__d)
swap(*__first, *(__first + __uid(__g, _P(0, __d)))); {
difference_type __i = __uid(__g, _P(0, __d));
if (__i != difference_type(0))
swap(*__first, *(__first + __i));
}
} }
} }