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/* Serialization of boost::bloom::filter.
*
* Copyright 2025 Joaquin M Lopez Munoz.
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*
* See https://www.boost.org/libs/bloom for library home page.
*/
#include <boost/bloom/filter.hpp>
#include <boost/bloom/multiblock.hpp>
#include <boost/core/detail/splitmix64.hpp>
#include <boost/uuid/uuid.hpp>
#include <cstdint>
#include <cstring>
#include <fstream>
#include <iostream>
/* emits a deterministic pseudorandom sequence of UUIDs */
struct uuid_generator
{
boost::uuids::uuid operator()()
{
std::uint8_t data[16];
std::uint64_t x = rng();
std::memcpy(&data[0], &x, sizeof(x));
x = rng();
std::memcpy(&data[8], &x, sizeof(x));
return {data};
}
boost::detail::splitmix64 rng;
};
using filter = boost::bloom::filter<
boost::uuids::uuid, 1, boost::bloom::multiblock<std::uint64_t, 8> >;
static constexpr std::size_t num_elements = 10000;
/* creates a filter with num_elements UUIDs */
filter create_filter()
{
uuid_generator gen;
filter f(num_elements, 0.005);
for(std::size_t i = 0; i < num_elements; ++i) f.insert(gen());
return f;
}
void save_filter(const filter& f, const char* filename)
{
std::ofstream out(filename, std::ios::binary | std::ios::trunc);
std::size_t c=f.capacity();
out.write(reinterpret_cast<const char*>(&c), sizeof(c)); /* save capacity (bits) */
auto s = f.array();
out.write(reinterpret_cast<const char*>(s.data()), s.size()); /* save array */
}
filter load_filter(const char* filename)
{
std::ifstream in(filename, std::ios::binary);
std::size_t c;
in.read(reinterpret_cast<char*>(&c), sizeof(c));
filter f(c);
auto s = f.array();
in.read(reinterpret_cast<char*>(s.data()), s.size()); /* load array */
return f;
}
int main()
{
static constexpr const char* filename = "filter.bin";
auto f1 = create_filter();
save_filter(f1, filename);
auto f2 = load_filter(filename);
if (f1 == f2) std::cout << "serialization correct\n";
else std::cout << "something went wrong\n";
}
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