在boost r树中存储原始指针的问题

Issue storing raw pointers in boost R-tree

本文关键字：原始 指针 问题 存储 boost      更新时间：2023-10-16

当试图从r-tree中删除值时，我得到编译错误。我还将一个原始指针与盒子一起存储，这似乎导致了问题-如果我存储int, string或shared_ptr，我不会得到错误。

我没有切换到shared_ptr的选项，因为所有这些都来自遗留库。有其他的解决方法吗?

我将树定义如下:

namespace bg = boost::geometry;
namespace bgi = boost::geometry::index;
namespace bgm = boost::geometry::model;
typedef boost::geometry::model::point<float, 2, bg::cs::cartesian> point_t;
typedef boost::geometry::model::box<point_t> box_t;
typedef std::pair<box_t, Data*> value_t;
boost::geometry::index::rtree<value_t, boost::geometry::index::quadratic<16>> rtree;

失败的代码如下:

while(!rtree.empty()) {
   auto it = rtree.begin();
   auto value = *it;
   rtree.remove(value); // <-- this is where the error appears.
}

错误如下:

...../boost/geometry/index/equal_to.hpp:127:60: error: ambiguous class template instantiation for 'struct boost::geometry::index::detail::equals<NdsInstance*, void>'
         && detail::equals<T2>::apply(l.second, r.second);
                                                        ^
...../boost/geometry/index/equal_to.hpp:28:8: error: candidates are: struct boost::geometry::index::detail::equals<Geometry*, Tag>
struct equals<Geometry *, Tag>
       ^
...../boost/geometry/index/equal_to.hpp:37:8: error:                 struct boost::geometry::index::detail::equals<T, void>
struct equals<T, void> 
       ^
...../boost/geometry/index/equal_to.hpp:127:60: error: incomplete type 'boost::geometry::index::detail::equals<NdsInstance*, void>' used in nested name specifier
         && detail::equals<T2>::apply(l.second, r.second);
                                                        ^

完整的代码示例可以在Colliru上找到。我使用gcc 4.9.3和boost 1.62(与boost 1.61相同的错误)。

我有同样的问题，我找到另一种方式走动:

重新定义一个equal_to函子(rtree的第四个模板实参)

示例代码:

#include <boost/geometry.hpp>
namespace bg = boost::geometry;
namespace bgi = boost::geometry::index;
namespace bgm = boost::geometry::model;
using point = bgm::point<double, 2, bg::cs::spherical_equatorial<bg::degree>>;
using value_type = std::pair<point, int*>;
struct my_equal { 
    using result_type = bool; 
    bool operator() (value_type const& v1, value_type const& v2) const { 
        return bg::equals(v1.first, v2.first) && v1.second == v2.second;} 
}; 
using rtree = bgi::rtree<value_type, bgi::quadratic<16>, bgi::indexable<value_type>, my_equal>;
int main() {
    int a,b;
    rtree rtree;
    rtree.insert(std::make_pair(point(45,45), &a));
    rtree.insert(std::make_pair(point(45,45), &b));
    rtree.remove(std::make_pair(point(45,45), &b));
    return 0;
}

在GCC 6.2.1, boost 1.61.0(也在GCC 4.9.3和boost 1.58.0)

灵感来自这张票

最后为原始指针创建了一个包装器:

struct wrapData {
    public:
    wrapData(Data *data) { _data = data; }
    operator Data*() const { return _data; }
    private:
    Data *_data;
};
typedef std::pair<box_t, wrapData> value_t;
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