smart_ptr_keys.h

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// SPDX-License-Identifier: GPL-2.0-or-later
#ifndef INKSCAPE_UTIL_SMART_PTR_KEYS_H
#define INKSCAPE_UTIL_SMART_PTR_KEYS_H
 
#include <functional> // for std::hash
 
template <typename T>
struct TransparentPtrHash
{
    using is_transparent = void;
 
    template <typename U>
    size_t operator()(U const &u) const
    {
        return std::hash<T const *>{}(&*u);
    }
};
 
template <typename T>
struct TransparentPtrLess
{
    using is_transparent = void;
 
    template <typename U, typename V>
    bool operator()(U const &u, V const &v) const
    {
        using Tp = T const *;
        return Tp{&*u} < Tp{&*v};
    }
};
 
template <typename T>
struct TransparentPtrEqual
{
    using is_transparent = void;
 
    template <typename U, typename V>
    bool operator()(U const &u, V const &v) const
    {
        using Tp = T const *;
        return Tp{&*u} == Tp{&*v};
    }
};
 
#endif // INKSCAPE_UTIL_SMART_PTR_KEYS_H