function it_denies_existence_of_items_not_in_set(BitField $bitField, MultiHash $multiHash)
{
$multiHash->hash('my string')->willReturn([1, 4]);
$bitField->has(1)->willReturn(false);
$bitField->has(4)->willReturn(true);
$this->contains('my string')->shouldReturn(false);
}
/**
* @param $expectedValues
* @param float $falsePositiveProbability
* @return BloomFilter
*/
public static function generate($expectedValues, $falsePositiveProbability = 0.1)
{
$sizeOfBitField = (int) ceil($expectedValues * log($falsePositiveProbability) / log(1 / pow(2, log(2))));
$hashFunctions = (int) ($sizeOfBitField / $expectedValues * log(2));
$multiHash = new MultiHash(new DJBX33X(), new FNVHash());
$multiHash->setUpperBound($sizeOfBitField);
$multiHash->setHashCount($hashFunctions);
return new BloomFilter(new BitField($sizeOfBitField), $multiHash);
}
