transparent_string_hash.h

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/*
 * Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration.
 */
#ifndef CXXUTILS_TRANSPARENT_STRING_HASH_H
#define CXXUTILS_TRANSPARENT_STRING_HASH_H
 
#include <cstddef>
#include <functional> // std::hash
#include <string>
#include <string_view>
 
namespace CxxUtils {

  struct TransparentStringHash{
    using is_transparent = void;

    std::size_t
    operator()(std::string_view s) const{
      return std::hash<std::string_view>{}(s);
    }

    std::size_t
    operator()(const std::string& s) const{
      return (*this)(std::string_view{s});
    }

    std::size_t
    operator()(const char* s) const{
      return (*this)(std::string_view{s});
    }
  };
 
} // namespace CxxUtils
 
#endif