.. _program_listing_file_src_rdf4cpp_util_Anonymizer.cpp:

Program Listing for File Anonymizer.cpp
=======================================

|exhale_lsh| :ref:`Return to documentation for file <file_src_rdf4cpp_util_Anonymizer.cpp>` (``src/rdf4cpp/util/Anonymizer.cpp``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   #include <rdf4cpp/util/Anonymizer.hpp>
   #include <rdf4cpp/IRIFactory.hpp>
   
   #include <ranges>
   #include <format>
   
   #include <openssl/err.h>
   #include <openssl/rand.h>
   
   namespace rdf4cpp::util {
   
   inline constexpr std::array chars{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k',
                                     'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
                                     'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G',
                                     'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R',
                                     'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'};
   
   struct GlobalCryptoRng {
       using result_type = uint64_t;
   
       constexpr GlobalCryptoRng() noexcept = default;
   
       [[nodiscard]] result_type operator()() const {
           std::array<unsigned char, sizeof(result_type)> buf;
   
           int const ret = RAND_bytes(buf.data(), buf.size());
           if (ret != 1) [[unlikely]] {
               std::array<char, 120> err_buf;
               unsigned long const code = ERR_get_error();
               ERR_error_string_n(code, err_buf.data(), err_buf.size());
   
               throw std::runtime_error{std::format("Unable to generate random bytes for anonymizer: {}", std::string_view{err_buf.data()})};
           }
   
           return std::bit_cast<result_type>(buf);
       }
   
       static constexpr result_type min() noexcept {
           return std::numeric_limits<result_type>::min();
       }
   
       static constexpr result_type max() noexcept {
           return std::numeric_limits<result_type>::max();
       }
   };
   inline constexpr GlobalCryptoRng global_crypto_rng;
   
   
   Anonymizer::Anonymizer(storage::DynNodeStoragePtr node_storage)
       : dist_{0, chars.size() - 1},
         node_storage_{node_storage} {
   }
   
   void Anonymizer::gen_random_id(std::span<char> out) {
       std::ranges::generate(out, [this] {
           return chars[dist_(global_crypto_rng)];
       });
   }
   
   storage::DynNodeStoragePtr Anonymizer::node_storage() const noexcept {
       return node_storage_;
   }
   
   IRI Anonymizer::anonymize(Node const &non_anon) {
       using namespace storage::identifier;
   
       if (non_anon.null() || non_anon.as_iri().is_default_graph()) {
           return non_anon.as_iri();
       }
   
       if (auto it = lookup_.find(non_anon.backend_handle()); it != lookup_.end()) {
           return IRI{NodeBackendHandle{it->second, node_storage_}};
       }
   
       std::array<char, IRIFactory::default_base.size() + 16> buf;
       std::ranges::copy(IRIFactory::default_base, buf.begin());
       gen_random_id(std::span{buf}.subspan(IRIFactory::default_base.size()));
   
       auto anon = IRI::make(std::string_view{buf.data(), buf.size()}, node_storage_);
       lookup_.emplace(non_anon.backend_handle(), anon.backend_handle().id());
   
       return anon;
   }
   
   Statement Anonymizer::anonymize(Statement const &non_anon) {
       return Statement{
           anonymize(non_anon.subject()),
           anonymize(non_anon.predicate()),
           anonymize(non_anon.object())
       };
   }
   
   Quad Anonymizer::anonymize(Quad const &non_anon) {
       return Quad{
           anonymize(non_anon.graph()),
           anonymize(non_anon.subject()),
           anonymize(non_anon.predicate()),
           anonymize(non_anon.object())
       };
   }
   
   } // namespace rdf4cpp::util