bloom-filter.H

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/*
                          Aleph_w
 
  Data structures & Algorithms
  version 2.0.0b
  https://github.com/lrleon/Aleph-w
 
  This file is part of Aleph-w library
 
  Copyright (c) 2002-2026 Leandro Rabindranath Leon
 
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
 
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
 
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
*/
 
 
# ifndef BLOOM_FILTER_H
# define BLOOM_FILTER_H
 
# include <cstddef>
# include <memory>
# include <tuple>
# include <vector>
# include <limits>
# include <ctime>
# include <gsl/gsl_rng.h>
# include <cmath>
# include <ahFunctional.H>
# include <bitArray.H>
# include <hash-fct.H>
# include <tpl_dynSetHash.H>
# include <ah-errors.H>
 
namespace Aleph
{
  template <typename T>
  class Bloom_Filter
  {
  public:
    using Hash_Fct = size_t (*)(const T &, unsigned long seed);
 
  private:
    BitArray bits;
 
    Hash_Fct hash_fct = nullptr;
    size_t num_hash = 0;
    std::vector<unsigned long> seeds;
    size_t num_ins = 0;
 
    bool have_same_hashes(const Bloom_Filter & f) const noexcept
    {
      return get_m() == f.get_m() and get_k() == f.get_k() and
             hash_fct == f.hash_fct and seeds == f.seeds;
    }
 
    Bloom_Filter(std::tuple<size_t, size_t> mk,
                 Hash_Fct hash_fn, unsigned long seed)
      : Bloom_Filter(std::get<0>(mk), std::get<1>(mk), hash_fn, seed)
    {
    }
 
  public:
    [[nodiscard]] static std::tuple<size_t, size_t> estimate(const size_t n, const double p)
    {
      ah_invalid_argument_if(n == 0) << "n must be > 0";
      ah_invalid_argument_if(p <= 0 or p >= 1) << "p must be in (0, 1)";
      const double log2 = std::log(2);
      const auto m = static_cast<size_t>(std::ceil(-(n * std::log(p)) / (log2 * log2)));
      const auto k = static_cast<size_t>(std::ceil((1.0 * m / n) * log2));
      return std::make_tuple(m, k);
    }
 
    [[nodiscard]] size_t get_m() const noexcept { return bits.size(); }
 
    [[nodiscard]] size_t get_k() const noexcept { return num_hash; }
 
    [[nodiscard]] size_t get_n() const noexcept { return num_ins; }
 
    [[nodiscard]] size_t get_x() const noexcept
    {
      size_t x = 0;
      for (size_t i = 0; i < bits.size(); ++i)
        if (bits(i) == 1)
          ++x;
      return x;
    }
 
    [[nodiscard]] size_t size() const noexcept { return get_n(); }
 
    [[nodiscard]] size_t capacity() const noexcept { return get_m(); }
 
    Bloom_Filter(const size_t dim, size_t num_hashes,
                 Hash_Fct hash_fn = dft_seed_hash_ptr_fct<T>,
                 const unsigned long seed = static_cast<unsigned long>(std::time(nullptr)))
      : bits(0), hash_fct(hash_fn), num_hash(num_hashes),
        seeds(num_hashes)
    {
      ah_invalid_argument_if(dim == 0) << "Bloom filter dimension must be > 0";
      ah_invalid_argument_if(num_hash == 0) << "Bloom filter number of hashes must be > 0";
      ah_invalid_argument_if(hash_fct == nullptr) << "Bloom filter hash function is null";
 
      bits.reserve(dim);
      const std::unique_ptr<gsl_rng, void(*)(gsl_rng *)>
          r(gsl_rng_alloc(gsl_rng_mt19937), gsl_rng_free);
      ah_bad_alloc_if(r.get() == nullptr);
      gsl_rng_set(r.get(), seed % gsl_rng_max(r.get()));
 
      for (auto & s: seeds)
        s = gsl_rng_get(r.get());
    }
 
    Bloom_Filter(const size_t n, const double p,
                 unsigned long seed = static_cast<unsigned long>(std::time(nullptr)),
                 Hash_Fct hash_fn = dft_seed_hash_ptr_fct<T>)
      : Bloom_Filter(estimate(n, p), hash_fn, seed)
    {
    }
 
    void swap(Bloom_Filter & f) noexcept
    {
      bits.swap(f.bits);
      std::swap(hash_fct, f.hash_fct);
      std::swap(num_hash, f.num_hash);
      seeds.swap(f.seeds);
      std::swap(num_ins, f.num_ins);
    }
 
    Bloom_Filter(const Bloom_Filter & f)
      : bits(f.bits), hash_fct(f.hash_fct), num_hash(f.num_hash),
        seeds(f.seeds), num_ins(f.num_ins)
    {
      // empty
    }
 
    Bloom_Filter(Bloom_Filter && f) noexcept
    {
      swap(f);
    }
 
    auto &operator =(const Bloom_Filter & f)
    {
      Bloom_Filter tmp(f);
      swap(tmp);
      return *this;
    }
 
    auto &operator =(Bloom_Filter && f) noexcept
    {
      swap(f);
      return *this;
    }
 
    ~Bloom_Filter() = default;
 
    auto &insert(const T & item)
    {
      const size_t m = bits.size();
      for (const auto & seed: seeds)
        bits.fast_write((*hash_fct)(item, seed) % m, 1);
 
      ++num_ins;
 
      return *this;
    }
 
    auto &append(const T & item) { return insert(item); }
 
    [[nodiscard]] bool contains(const T & item) const
    {
      const size_t m = bits.size();
      for (const auto & seed: seeds)
        if (not bits.fast_read((*hash_fct)(item, seed) % m))
          return false;
 
      return true;
    }
 
    [[nodiscard]] DynList<size_t> hash_seeds() const
    {
      DynList<size_t> ret;
      for (const auto & seed: seeds)
        ret.append(seed);
      return ret;
    }
 
    [[nodiscard]] DynList<size_t> hashes(const T & item) const
    {
      DynList<size_t> ret;
      const size_t m = bits.size();
      for (const auto & seed: seeds)
        ret.append((*hash_fct)(item, seed) % m);
      return ret;
    }
 
    [[nodiscard]] DynList<size_t> common_hashes(const T & i1, const T & i2) const
    {
      return intercept(hashes(i1), hashes(i2));
    }
 
    [[nodiscard]] DynList<size_t> set_bits() const
    {
      DynList<size_t> ret;
      for (size_t i = 0; i < bits.size(); ++i)
        if (bits(i) == 1)
          ret.append(i);
 
      return ret;
    }
 
    [[nodiscard]] size_t expected_size(const size_t x) const noexcept
    {
      const auto m = static_cast<double>(capacity());
      const auto k = static_cast<double>(get_k());
      if (m == 0 or k == 0)
        return 0;
 
      const double p0 = 1.0 - (static_cast<double>(x) / m);
      if (p0 <= 0)
        return std::numeric_limits<size_t>::max();
 
      const double n = std::ceil(-(m * std::log(p0)) / k);
      if (not std::isfinite(n) or n < 0)
        return std::numeric_limits<size_t>::max();
 
      return static_cast<size_t>(n);
    }
 
    [[nodiscard]] size_t expected_size() const noexcept
    {
      return expected_size(get_x());
    }
 
    auto &operator |=(const Bloom_Filter & f)
    {
      ah_domain_error_if(not have_same_hashes(f))
        << "Bloom filter have different hashes";
 
      bits |= f.bits;
 
      const auto x = get_x();
 
      num_ins = expected_size(x);
 
      return *this;
    }
 
    auto &operator &=(const Bloom_Filter & f)
    {
      ah_domain_error_if(not have_same_hashes(f))
        << "Bloom filter have different hashes";
 
      bits &= f.bits;
 
      num_ins = expected_size();
 
      return *this;
    }
 
    friend Bloom_Filter
    operator |(const Bloom_Filter & f1, const Bloom_Filter & f2)
    {
      Bloom_Filter ret = f1;
      ret |= f2;
      return ret;
    }
 
    friend Bloom_Filter
    operator &(const Bloom_Filter & f1, const Bloom_Filter & f2)
    {
      Bloom_Filter ret = f1;
      ret &= f2;
      return ret;
    }
  };
} // end namespace Aleph
 
# endif // BLOOM_FILTER_H