hash.h

#ifndef BF_HASH_POLICY_H
#define BF_HASH_POLICY_H

#include <functional>
#include <bf/h3.h>
#include <bf/object.h>

namespace bf {

typedef size_t digest;

typedef std::function<digest(object const&)> hash_function;

typedef std::function<std::vector<digest>(object const&)> hasher;

class default_hash_function
{
public:
  constexpr static size_t max_obj_size = 36;

  default_hash_function(size_t seed);

  size_t operator()(object const& o) const;

private:
  h3<size_t, max_obj_size> h3_;
};

class default_hasher
{
public:
  default_hasher(std::vector<hash_function> fns);

  std::vector<digest> operator()(object const& o) const;

private:
  std::vector<hash_function> fns_;
};

class double_hasher
{
public:
  double_hasher(size_t k, hash_function h1, hash_function h2);

  std::vector<digest> operator()(object const& o) const;

private:
  size_t k_;
  hash_function h1_;
  hash_function h2_;
};

hasher make_hasher(size_t k, size_t seed = 0, bool double_hashing = false);

} // namespace bf

#endif