56 lines
1.6 KiB
C++
56 lines
1.6 KiB
C++
// Copyright (C) 2019 T. Zachary Laine
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//[ random_access_iterator
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#include <boost/stl_interfaces/iterator_interface.hpp>
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#include <algorithm>
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#include <array>
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#include <cassert>
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// This is a minimal random access iterator. It uses default template
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// parameters for most stl_interfaces template parameters.
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struct simple_random_access_iterator
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: boost::stl_interfaces::iterator_interface<
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simple_random_access_iterator,
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std::random_access_iterator_tag,
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int>
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{
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// This default constructor does not initialize it_, since that's how int *
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// works as well. This allows optimum performance in code paths where
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// initializing a single pointer may be measurable. It is also a
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// reasonable choice to initialize with nullptr.
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simple_random_access_iterator() noexcept {}
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simple_random_access_iterator(int * it) noexcept : it_(it) {}
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int & operator*() const noexcept { return *it_; }
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simple_random_access_iterator & operator+=(std::ptrdiff_t i) noexcept
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{
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it_ += i;
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return *this;
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}
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auto operator-(simple_random_access_iterator other) const noexcept
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{
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return it_ - other.it_;
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}
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private:
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int * it_;
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};
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int main()
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{
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std::array<int, 10> ints = {{0, 2, 1, 3, 4, 5, 7, 6, 8, 9}};
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simple_random_access_iterator first(ints.data());
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simple_random_access_iterator last(ints.data() + ints.size());
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std::sort(first, last);
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assert(ints == (std::array<int, 10>{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}}));
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}
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//]
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