Program Listing for File CuckooHashing.h

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/*--------------------------------------------------------------------------*/
/*-------------------------- File CuckooHashing.h --------------------------*/
/*--------------------------------------------------------------------------*/
/*--------------------------------------------------------------------------*/
/*----------------------------- DEFINITIONS --------------------------------*/
/*--------------------------------------------------------------------------*/

#ifndef __ADS_CuckooHashing
 #define __ADS_CuckooHashing
                      /* self-identification: #endif constant */

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/*------------------------------ INCLUDES ----------------------------------*/
/*--------------------------------------------------------------------------*/

#include "ADS/Contract.h"
#include "ADS/Iterators.h"
#include "ADS/dictionary/RandomHashing.h"

#include <bit>
#include <cstddef>
#include <cstdint>
#include <functional>
#include <optional>
#include <utility>
#include <vector>

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/*--------------------------- NAMESPACE ------------------------------------*/
/*--------------------------------------------------------------------------*/

namespace ADS {

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/*------------------------- CLASS CuckooHashTable --------------------------*/
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template< class K , class V , class H = std::hash< K > >
class CuckooHashTable {

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 public:

 using Key = K;
 using Value = V;

 explicit CuckooHashTable( std::size_t m = 16 , double maxLoad = 0.4 ,
                           std::size_t s = 0 , std::uint64_t seed = 1 ,
                           H h = H() );

 [[nodiscard]] std::optional< V > lookup( const K & k ) const;

 void insert( const K & k , const V & v );

 void remove( const K & k );

 [[nodiscard]] bool contains( const K & k ) const;

 [[nodiscard]] std::size_t size( void ) const;

 [[nodiscard]] std::size_t capacity( void ) const;

 [[nodiscard]] std::size_t rehashes( void ) const;

 [[nodiscard]] std::size_t evictions( void ) const;

 [[nodiscard]] std::size_t stashed( void ) const;

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 private:

 struct Cell {
  bool full = false;
  K key{};
  V value{};
  };

 public:

/*------------------------- THE STANDARD INTERFACE -------------------------*/

 // a constant view of the pairs ( key , value ), in the order of the
 // places and then of the stash, bidirectional; an insertion or a removal
 // invalidates it

 struct Places {
  static std::size_t size( const auto & o ) { return( o.f_T.size() ); }
  static bool occupied( const auto & o , std::size_t i ) {
   return( o.f_T[ i ].full );
   }
  static auto read( const auto & o , std::size_t i ) {
   return( std::pair< const K & , const V & >( o.f_T[ i ].key ,
                                              o.f_T[ i ].value ) );
   }
  };

 using value_type = std::pair< const K & , const V & >;
 using size_type = std::size_t;
 using difference_type = std::ptrdiff_t;
 using reference = std::pair< const K & , const V & >;
 using const_reference = std::pair< const K & , const V & >;
 using const_iterator = SlotIterator< CuckooHashTable , Places >;
 using iterator = const_iterator;

 [[nodiscard]] const_iterator begin( void ) const {
  return( const_iterator( this , 0 ) );
  }
 [[nodiscard]] const_iterator end( void ) const {
  return( const_iterator( this , f_T.size() ) );
  }
 [[nodiscard]] const_iterator cbegin( void ) const { return( begin() ); }
 [[nodiscard]] const_iterator cend( void ) const { return( end() ); }

 private:

 [[nodiscard]] std::size_t place( const K & k , int i ) const;

 [[nodiscard]] std::optional< std::size_t > find( const K & k ) const;

 bool walk( Cell & c );

 bool settle( Cell & c );

 void rebuild( std::size_t m , std::optional< Cell > extra );

 void draw( void );

 [[nodiscard]] bool placed( const K & k ) const;

 std::vector< Cell > f_T;
 std::size_t f_m;
 std::size_t f_m0;
 std::size_t f_s;
 double f_maxLoad;
 std::size_t f_n = 0;
 std::size_t f_rehashes = 0;
 std::size_t f_evictions = 0;
 SplitMix64 f_seeds;
 TabulationHash f_g1 , f_g2;
 H f_h;

 };  // end( class CuckooHashTable )

/*--------------------------------------------------------------------------*/

}  // end( namespace ADS )

/*--------------------------------------------------------------------------*/
/*-------------------------- IMPLEMENTATION --------------------------------*/
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#include "ADS/dictionary/impl/CuckooHashing.tpp"

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#endif  /* CuckooHashing.h included */

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/*------------------------ End File CuckooHashing.h ------------------------*/
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