46 lines
1.2 KiB
C++
46 lines
1.2 KiB
C++
#pragma once
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#include <boost/iterator/iterator_adaptor.hpp>
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template <typename Iterator>
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class striding_iterator : public boost::iterator_adaptor<striding_iterator<Iterator>, Iterator> {
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typedef boost::iterator_adaptor<striding_iterator<Iterator>, Iterator> super_t;
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friend class boost::iterator_core_access;
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public:
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striding_iterator()
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: super_t()
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, stride(1)
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{}
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striding_iterator(Iterator it, int stride)
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: super_t(it)
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, stride(stride)
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{}
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template<class OtherIterator>
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striding_iterator(striding_iterator<OtherIterator> const& r, typename boost::enable_if_convertible<OtherIterator, Iterator>::type* = 0)
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: super_t(r.base())
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{}
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int stride;
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private:
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void advance(typename super_t::difference_type n){
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this->base_reference() += stride * n;
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}
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template <class OtherIterator>
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typename super_t::difference_type distance_to(striding_iterator<OtherIterator> const & that) const {
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int s = that.base() - this->base();
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if(s >= 0) return (s + stride - 1) / stride;
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return (s - stride + 1) / stride;
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}
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void increment() { advance(1); }
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void decrement() { advance(-1); }
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};
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template <typename Iterator>
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striding_iterator<Iterator> strided(Iterator it, int stride = 1){
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return striding_iterator<Iterator>(it, stride);
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}
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