如何使我的容器与 boost::range 兼容？

Question

我正在滚动一个自定义的、类似标准的容器，我想让它与 boost::range 库兼容。

到目前为止它适用于所有STL算法并且它还满足以下条件：

BOOST_CONCEPT_ASSERT((boost::InputIterator<my_container::const_iterator>));
BOOST_CONCEPT_ASSERT((boost::Container<my_container>));

但是当我尝试在这种情况下使用它时：

auto r = c | boost::adaptors::indexed();

它似乎缺少一些模板化的元数据。错误类似于

error: no type named 'type' in boost::range::iterator<my_container, void>
>> typename range_iterator<SinglePassRange>::type

是否有类似的概念 assert 我可以用来帮助我完成我的类型缺少的实现？或者甚至是一篇解释如何使容器 boost::range 兼容的文章？我假设我不需要在我的实现中实际包含增强类型，因为 STL 显然不需要。

非常感谢任何帮助！ :-)

编辑：最小（大概）示例

#include <catch2/catch.hpp>

#include <boost/concept_check.hpp>
#include <boost/concept/assert.hpp>
#include <boost/range/adaptor/indexed.hpp>

#include <algorithm>

SCENARIO("container")
{
    class my_container
    {
    public:
        class const_iterator
        {
        public:
            using value_type = const int;
            using pointer = const int*;
            using reference = const int&;
            using difference_type = std::ptrdiff_t;
            using iterator_category = std::input_iterator_tag;
            const_iterator() = default;
            bool operator==(const_iterator other) const noexcept { return d == other.d; }
            bool operator!=(const_iterator other) const noexcept { return !(*this == other); }
            reference operator*() const { return *d; }
            pointer operator->() const { return d; }
            const_iterator& operator++() { ++d; return *this; }
            const_iterator operator++(int) { return d++; }
        private:
            friend my_container;
            const_iterator(const int* p) : d(p) {}
            const int* d{nullptr};
        };
        using value_type = int;
        using const_reference = const int&;
        using const_pointer = const int*;
        using size_type = std::size_t;
        using difference_type = std::ptrdiff_t;
        my_container() : data({0, 1, 2, 3, 4}) {}
        const_iterator begin() const { return const_iterator(data.data()); }
        const_iterator end() const { return const_iterator(data.data() + 5); }
        size_type size() const { return 5; }
        size_type max_size() const { return 5; }
        bool empty() const { return false; }
    private:
        std::array<int, 5> data;
    };

    BOOST_CONCEPT_ASSERT((boost::InputIterator<my_container::const_iterator>));
    BOOST_CONCEPT_ASSERT((boost::Container<my_container>));

    GIVEN("a container") {
        my_container container;
        WHEN("use std::algorithms") {
            auto itr = std::find(container.begin(), container.end(), 3);
            THEN("element is found") {
                CHECK(itr != container.end());
            }
        }
        WHEN("use boost range") {
            // wont compile
            auto r = container | boost::adaptors::indexed();
        }
    }
}

Answer 1

您需要 iterator 以及 const_iterator。尝试：

    using iterator = const_iterator;

如何使我的容器与 boost::range 兼容？

How can I make my container compatible with boost::range?

c++

boost

boost-range