92 lines
3.2 KiB
C++
92 lines
3.2 KiB
C++
#ifndef INTEGER_RANGE_HPP
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#define INTEGER_RANGE_HPP
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#include <boost/assert.hpp>
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#include <boost/iterator/iterator_facade.hpp>
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#include <type_traits>
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#include <cstdint>
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namespace osrm::util
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{
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// Ported from Boost.Range 1.56 due to required fix
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// https://github.com/boostorg/range/commit/9e6bdc13ba94af4e150afae547557a2fbbfe3bf0
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// Can be removed after dropping support of Boost < 1.56
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template <typename Integer>
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class integer_iterator : public boost::iterator_facade<integer_iterator<Integer>,
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Integer,
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boost::random_access_traversal_tag,
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Integer>
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{
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using base_t = boost::iterator_facade<integer_iterator<Integer>,
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Integer,
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boost::random_access_traversal_tag,
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Integer>;
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public:
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using value_type = typename base_t::value_type;
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using difference_type = typename base_t::difference_type;
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using reference = typename base_t::reference;
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using iterator_category = std::random_access_iterator_tag;
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integer_iterator() : m_value() {}
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explicit integer_iterator(value_type x) : m_value(x) {}
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private:
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void increment() { ++m_value; }
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void decrement() { --m_value; }
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void advance(difference_type offset) { m_value += offset; }
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bool equal(const integer_iterator &other) const { return m_value == other.m_value; }
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reference dereference() const { return m_value; }
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difference_type distance_to(const integer_iterator &other) const
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{
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return std::is_signed<value_type>::value ? (other.m_value - m_value)
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: (other.m_value >= m_value)
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? static_cast<difference_type>(other.m_value - m_value)
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: -static_cast<difference_type>(m_value - other.m_value);
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}
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friend class ::boost::iterator_core_access;
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value_type m_value;
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};
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// Warning: do not try to replace this with Boost's irange, as it is broken on Boost 1.55:
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// auto r = boost::irange<unsigned int>(0, 15);
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// std::cout << r.size() << std::endl;
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// results in -4294967281. Latest Boost versions fix this, but we still support older ones.
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template <typename Integer> class range
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{
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public:
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using const_iterator = integer_iterator<Integer>;
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using iterator = integer_iterator<Integer>;
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range(Integer begin, Integer end) : iter(begin), last(end) {}
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iterator begin() const noexcept { return iter; }
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iterator end() const noexcept { return last; }
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Integer front() const noexcept { return *iter; }
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Integer back() const noexcept { return *last - 1; }
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std::size_t size() const noexcept { return static_cast<std::size_t>(last - iter); }
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private:
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iterator iter;
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iterator last;
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};
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// convenience function to construct an integer range with type deduction
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template <typename Integer>
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range<Integer>
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irange(const Integer first,
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const Integer last,
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typename std::enable_if<std::is_integral<Integer>::value>::type * = nullptr) noexcept
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{
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return range<Integer>(first, last);
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}
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} // namespace osrm::util
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#endif // INTEGER_RANGE_HPP
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