transparent_eq.h

#ifndef CACHEMERE_TRANSPARENT_EQ_H
#define CACHEMERE_TRANSPARENT_EQ_H
 
#include <absl/hash/hash.h>
 
namespace cachemere::detail {
 
template<typename Key> struct TransparentEq {
    // Declare this type as transparent - this is needed for abseil maps to support heterogeneous lookup.
    using is_transparent = void;
 
    bool operator()(const Key& a, const Key& b) const
    {
        return a == b;
    }
 
    template<typename KeyView> bool operator()(const Key& a, const KeyView& b) const
    {
        // We only require operator==(const Key&) to be defined on the KeyView.
        return b == a;
    }
 
    template<typename KeyView> bool operator()(const KeyView& a, const Key& b) const
    {
        // We only require operator==(const Key&) to be defined on the KeyView.
        return a == b;
    }
};
 
}  // namespace cachemere::detail
 
#endif  // CACHEMERE_TRANSPARENT_EQ_H