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47 lines
1.4 KiB
C++
47 lines
1.4 KiB
C++
#pragma once
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#include <type_traits>
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#include <utility>
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#include <iterator>
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#include <boost/iterator/counting_iterator.hpp>
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/** Numeric range iterator, used to represent a half-closed interval [begin, end).
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* In conjunction with std::reverse_iterator allows for forward and backward iteration
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* over corresponding interval.
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*/
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namespace ext
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{
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template <typename T>
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using range_iterator = boost::counting_iterator<T>;
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/** Range-based for loop adapter for (reverse_)range_iterator.
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* By and large should be in conjunction with ext::range and ext::reverse_range.
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*/
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template <typename T>
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struct range_wrapper
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{
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using value_type = typename std::remove_reference<T>::type;
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using iterator = range_iterator<value_type>;
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value_type begin_;
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value_type end_;
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iterator begin() const { return iterator(begin_); }
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iterator end() const { return iterator(end_); }
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};
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/** Constructs range_wrapper for forward-iteration over [begin, end) in range-based for loop.
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* Usage example:
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* for (const auto i : ext::range(0, 4)) print(i);
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* Output:
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* 0 1 2 3
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*/
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template <typename T1, typename T2>
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inline range_wrapper<typename std::common_type<T1, T2>::type> range(T1 begin, T2 end)
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{
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using common_type = typename std::common_type<T1, T2>::type;
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return { static_cast<common_type>(begin), static_cast<common_type>(end) };
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}
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}
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