cliqueHash.cpp

#include "cliqueHash.h"


size_t cliqueHash::hash_function(const clique key)
{
    const size_t keySize = key.size();


    // std::cerr << "clique size for hash_function is " << key.size() << "\n";
    size_t hash_key;
    size_t newInd[keySize];
    for (size_t i = 0; i < keySize; i++)
        newInd[i] = key.at(keySize-1-i) & b;


    //     for (size_t i = 1; i < keySize; i++) new_ind[i] = A*key.at(i);
    hash_key = newInd[0] << hash_bits - offSet; // move to the left
    size_t move;
    for (size_t i = 1; i < keySize; i++)
    {
        move = hash_bits - (i+1)*offSet;
        newInd[i] = newInd[i] << move;
        hash_key = hash_key | newInd[i] ;      // take
    }


    hash_key = hash_key | ( key.at(keySize-2) & c );

    // now take only the last hash_bits bits

    //     hash_key = hash_key & a;
    //     std::cerr << "hash key is: " << hash_key << "\n";

    /*
    hash_key = key.at(0)+1;
    for (size_t i = 1; i < key.size(); i++) hash_key *= key.at(i);
    hash_key = hash_key%size;
    //     hash_key = (key.at(0)+1)*key.at(1)*key.at(2)*key.at(3)%size;
    // hash_key = ( key.at(0) * key.at(3) + key.at(1) * key.at(2) )%size;
    */
    if (hash_key >= size || hash_key < 0 )
    {
        std::cerr << "hash function did not work!\n";
        // std::cerr << "nodes were: " << key.at(0) << " " << key.at(1) << " " << key.at(2) << " " << key.at(3) << "\n";
        std::cerr << "hash key was: " << hash_key << "\n";
        std::cerr << "hash key size was: " << keySize << "\n";	
    }


    return hash_key;
}


cliqueHash::cliqueHash(const size_t hashSize, const size_t t, const size_t keySize)
{
  hashTable.resize(hashSize); // reserve memory
    keyCount = 0;
    size = hashSize;
    hash_bits = t;
    offSet = hash_bits/keySize; // this is how much we can move bits for each index
    a = 1;
    a = a << hash_bits;
    a = a - 1;    // beginning is zeros, only hash_bits lasts bits are one
    b = 1;
    b = b << offSet;
    b = b-1;
    c = 1;
    c = c << ( hash_bits - keySize*offSet );
    c = c - 1;
}


cliqueHash::cliqueHash()
{
    cliqueHash(0, 1, 1);
}


bool cliqueHash::contains(const clique & key)
{
    // std::cerr << "entering contains-function\n";
    size_t hash_key = hash_function(key);
    //     std::cerr << "hash-key is:" << hash_key << "\n";

    bool key_found = false;
    for (cliqueIndexSet::iterator i = hashTable.at(hash_key).begin(); !key_found && i != hashTable.at(hash_key).end(); i++)
    {
        if ( (*i).first == key ) key_found = true;
    }
    //    std::cerr << "leaving contains-function\n";
    return key_found;
}


int cliqueHash::getValue(const clique & key)
{
    size_t hash_key = hash_function(key);

    int value = -1;
    bool key_found = false;
    for (cliqueIndexSet::iterator i = hashTable.at(hash_key).begin(); !key_found && i != hashTable.at(hash_key).end(); i++)
    {
        if ( (*i).first == key )
        {
            value = (*i).second;
            key_found = true;
        }
    }
    return value;
}


void cliqueHash::put(const clique & key, const size_t value)
{
    size_t hash_key = hash_function(key);

    if ( contains(key) )
    {
        bool key_found = false;
        for (cliqueIndexSet::iterator i = hashTable.at(hash_key).begin(); !key_found && i != hashTable.at(hash_key).end(); i++)
        {
            if ( (*i).first == key )
            {
                (*i).second = value;
                key_found = true;
            }
        }
    }
    else
    {
        std::pair<clique,size_t> cliqueValPair(key,value);
        hashTable.at(hash_key).push_back( cliqueValPair );
        keyCount++;
    }
}


std::pair<clique,size_t> cliqueHash::begin()
{
    curr_hash_key = 0;
    while ( curr_hash_key < size && hashTable.at(curr_hash_key).size() == 0  )
    {
        curr_hash_key++;
    }
    if ( curr_hash_key < size )         // now we have found the first slot that is not empty
    {
        iter = hashTable.at(curr_hash_key).begin();
        return *iter;
    }
    else
    {
        clique tmpClique;
        currPair = std::make_pair( tmpClique, 0);
        return currPair;
    }
}

std::pair<clique,size_t> cliqueHash::next()
{
    iter++;
    if ( iter == hashTable.at(curr_hash_key).end() )    // move to the next non-empty slot
    {
        do
        {
            curr_hash_key++;
        }
        while ( curr_hash_key < size && hashTable.at(curr_hash_key).size() == 0  );
        if ( curr_hash_key < size )         // now we have found the first slot that is not empty
        {
            iter = hashTable.at(curr_hash_key).begin();
            return *iter;
        }
        else
        {
            clique tmpClique;
            currPair = std::make_pair(tmpClique, 0);
            return currPair;
        }
    }
    else
    {
        return *iter;
    }
}


bool cliqueHash::finished()
{

    if ( curr_hash_key == size ) return true;
    else if ( getKeyCount() == 0 ) return true;
    else return false;

}