[libcxx] r217902 - Create a 'comma_iterator' class that overloads operator, and asserts when it's called. Add tests to mismatch to make sure it can't be blindsided by such an evil iterator. More tests for other algorithms forthcoming. Thanks to STL for pointing this out at CppCon and Yakov Galka for opening LWG issue #2133
David Blaikie
dblaikie at gmail.com
Tue Sep 16 14:13:04 PDT 2014
On Tue, Sep 16, 2014 at 1:38 PM, Marshall Clow <mclow.lists at gmail.com>
wrote:
> Author: marshall
> Date: Tue Sep 16 15:38:11 2014
> New Revision: 217902
>
> URL: http://llvm.org/viewvc/llvm-project?rev=217902&view=rev
> Log:
> Create a 'comma_iterator' class that overloads operator, and asserts when
> it's called. Add tests to mismatch to make sure it can't be blindsided by
> such an evil iterator. More tests for other algorithms forthcoming. Thanks
> to STL for pointing this out at CppCon and Yakov Galka for opening LWG
> issue #2133
>
Could it use "= delete" to make this test fail at compile-time?
>
> Modified:
>
> libcxx/trunk/test/algorithms/alg.nonmodifying/mismatch/mismatch.pass.cpp
>
> libcxx/trunk/test/algorithms/alg.nonmodifying/mismatch/mismatch_pred.pass.cpp
> libcxx/trunk/test/support/test_iterators.h
>
> Modified:
> libcxx/trunk/test/algorithms/alg.nonmodifying/mismatch/mismatch.pass.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/algorithms/alg.nonmodifying/mismatch/mismatch.pass.cpp?rev=217902&r1=217901&r2=217902&view=diff
>
> ==============================================================================
> ---
> libcxx/trunk/test/algorithms/alg.nonmodifying/mismatch/mismatch.pass.cpp
> (original)
> +++
> libcxx/trunk/test/algorithms/alg.nonmodifying/mismatch/mismatch.pass.cpp
> Tue Sep 16 15:38:11 2014
> @@ -36,6 +36,14 @@ int main()
> input_iterator<const int*>(ia+3),
> input_iterator<const int*>(ib+3))));
>
> + assert(std::mismatch(comma_iterator<const int*>(ia),
> + comma_iterator<const int*>(ia + sa),
> + comma_iterator<const int*>(ib)) ==
> + (std::pair<comma_iterator<const int*>,
> + comma_iterator<const int*> >(
> + comma_iterator<const int*>(ia+3),
> + comma_iterator<const int*>(ib+3))));
> +
> #ifdef HAS_FOUR_ITERATOR_VERSION
> assert(std::mismatch(input_iterator<const int*>(ia),
> input_iterator<const int*>(ia + sa),
>
> Modified:
> libcxx/trunk/test/algorithms/alg.nonmodifying/mismatch/mismatch_pred.pass.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/algorithms/alg.nonmodifying/mismatch/mismatch_pred.pass.cpp?rev=217902&r1=217901&r2=217902&view=diff
>
> ==============================================================================
> ---
> libcxx/trunk/test/algorithms/alg.nonmodifying/mismatch/mismatch_pred.pass.cpp
> (original)
> +++
> libcxx/trunk/test/algorithms/alg.nonmodifying/mismatch/mismatch_pred.pass.cpp
> Tue Sep 16 15:38:11 2014
> @@ -39,6 +39,14 @@ int main()
> input_iterator<const int*> >(
> input_iterator<const int*>(ia+3),
> input_iterator<const int*>(ib+3))));
> + assert(std::mismatch(comma_iterator<const int*>(ia),
> + comma_iterator<const int*>(ia + sa),
> + comma_iterator<const int*>(ib),
> + std::equal_to<int>()) ==
> + (std::pair<comma_iterator<const int*>,
> + comma_iterator<const int*> >(
> + comma_iterator<const int*>(ia+3),
> + comma_iterator<const int*>(ib+3))));
> #ifdef HAS_FOUR_ITERATOR_VERSION
> assert(std::mismatch(input_iterator<const int*>(ia),
> input_iterator<const int*>(ia + sa),
>
> Modified: libcxx/trunk/test/support/test_iterators.h
> URL:
> http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/support/test_iterators.h?rev=217902&r1=217901&r2=217902&view=diff
>
> ==============================================================================
> --- libcxx/trunk/test/support/test_iterators.h (original)
> +++ libcxx/trunk/test/support/test_iterators.h Tue Sep 16 15:38:11 2014
> @@ -284,6 +284,108 @@ operator-(const random_access_iterator<T
> return x.base() - y.base();
> }
>
> +template <class It>
> +class comma_iterator
> +{
> + It it_;
> +
> + template <class U> friend class comma_iterator;
> +public:
> + typedef std::random_access_iterator_tag
> iterator_category;
> + typedef typename std::iterator_traits<It>::value_type value_type;
> + typedef typename std::iterator_traits<It>::difference_type
> difference_type;
> + typedef It pointer;
> + typedef typename std::iterator_traits<It>::reference reference;
> +
> + It base() const {return it_;}
> +
> + comma_iterator() : it_() {}
> + explicit comma_iterator(It it) : it_(it) {}
> + template <class U>
> + comma_iterator(const comma_iterator<U>& u) :it_(u.it_) {}
> +
> + reference operator*() const {return *it_;}
> + pointer operator->() const {return it_;}
> +
> + comma_iterator& operator++() {++it_; return *this;}
> + comma_iterator operator++(int)
> + {comma_iterator tmp(*this); ++(*this); return tmp;}
> +
> + comma_iterator& operator--() {--it_; return *this;}
> + comma_iterator operator--(int)
> + {comma_iterator tmp(*this); --(*this); return tmp;}
> +
> + comma_iterator& operator+=(difference_type n) {it_ += n; return
> *this;}
> + comma_iterator operator+(difference_type n) const
> + {comma_iterator tmp(*this); tmp += n; return tmp;}
> + friend comma_iterator operator+(difference_type n, comma_iterator x)
> + {x += n; return x;}
> + comma_iterator& operator-=(difference_type n) {return *this += -n;}
> + comma_iterator operator-(difference_type n) const
> + {comma_iterator tmp(*this); tmp -= n; return tmp;}
> +
> + reference operator[](difference_type n) const {return it_[n];}
> + template <typename T>
> + void operator,(const T &) { assert(false); }
> +};
> +
> +template <class T, class U>
> +inline
> +bool
> +operator==(const comma_iterator<T>& x, const comma_iterator<U>& y)
> +{
> + return x.base() == y.base();
> +}
> +
> +template <class T, class U>
> +inline
> +bool
> +operator!=(const comma_iterator<T>& x, const comma_iterator<U>& y)
> +{
> + return !(x == y);
> +}
> +
> +template <class T, class U>
> +inline
> +bool
> +operator<(const comma_iterator<T>& x, const comma_iterator<U>& y)
> +{
> + return x.base() < y.base();
> +}
> +
> +template <class T, class U>
> +inline
> +bool
> +operator<=(const comma_iterator<T>& x, const comma_iterator<U>& y)
> +{
> + return !(y < x);
> +}
> +
> +template <class T, class U>
> +inline
> +bool
> +operator>(const comma_iterator<T>& x, const comma_iterator<U>& y)
> +{
> + return y < x;
> +}
> +
> +template <class T, class U>
> +inline
> +bool
> +operator>=(const comma_iterator<T>& x, const comma_iterator<U>& y)
> +{
> + return !(x < y);
> +}
> +
> +template <class T, class U>
> +inline
> +typename std::iterator_traits<T>::difference_type
> +operator-(const comma_iterator<T>& x, const comma_iterator<U>& y)
> +{
> + return x.base() - y.base();
> +}
> +
> +
> template <class Iter>
> inline Iter base(output_iterator<Iter> i) { return i.base(); }
>
> @@ -299,6 +401,9 @@ inline Iter base(bidirectional_iterator<
> template <class Iter>
> inline Iter base(random_access_iterator<Iter> i) { return i.base(); }
>
> +template <class Iter>
> +inline Iter base(comma_iterator<Iter> i) { return i.base(); }
> +
> template <class Iter> // everything else
> inline Iter base(Iter i) { return i; }
>
>
>
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