75 lines
1.6 KiB
C++
75 lines
1.6 KiB
C++
#pragma once
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#include "utils/option.hpp"
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namespace iter
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{
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// Class which wraps iterator with next() into C++ iterator.
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// T - type of return value
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// I - iterator type
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template <class T, class I>
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class RangeIterator
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{
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public:
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RangeIterator() : iter(Option<I>()), value(Option<T>()){};
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RangeIterator(I &&iter)
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: value(iter.next()), iter(Option<I>(std::move(iter)))
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{
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}
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T &operator*()
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{
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assert(value.is_present());
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return value.get();
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}
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T *operator->()
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{
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assert(value.is_present());
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return &value.get();
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}
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operator T &()
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{
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assert(value.is_present());
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return value.get();
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}
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RangeIterator &operator++()
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{
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assert(iter.is_present());
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value = iter.get().next();
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return (*this);
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}
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RangeIterator &operator++(int) { return operator++(); }
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friend bool operator==(const RangeIterator &a, const RangeIterator &b)
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{
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return a.value.is_present() == b.value.is_present();
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}
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friend bool operator!=(const RangeIterator &a, const RangeIterator &b)
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{
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return !(a == b);
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}
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private:
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Option<I> iter;
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Option<T> value;
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};
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template <class I>
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auto make_range_iterator(I &&iter)
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{
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// Because this function isn't receving or in any way using type T from
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// RangeIterator, compiler can't deduce it. That is the reason why
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// there is decltype in construction of RangeIterator.
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// declytype(iter.next().take()) is T.
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return RangeIterator<decltype(iter.next().take()), I>(std::move(iter));
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}
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}
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