Customisable FizzBuzz implementation in PHP.

example.php

<?php

$fizzbuzz = new \FizzBuzz\Application;
$fizzbuzz->addDefinition(new \FizzBuzz\Definition('Fizz', 3));
$fizzbuzz->addDefinition(new \FizzBuzz\Definition('Buzz', 5));

$fizzbuzz->run(1, 100);

fizzbuzz.php

<?php

namespace FizzBuzz;

class Definition
{
    private $name;
    private $divisor;

    public function __construct(string $name, int $divisor)
    {
        $this->name = $name;
        $this->divisor = $divisor;
    }

    public function getName(): string
    {
        return $this->name;
    }

    public function getDivisor(): int
    {
        return $this->divisor;
    }
}

class Application {
    const SEPARATOR = ', ';

    private $definitions = [];

    public function addDefinition(Definition $definition)
    {
        $conflicts = array_filter($this->definitions, function (Definition $existing) use ($definition) {
            return $existing->getName() === $definition->getName()
                || $existing->getDivisor() === $definition->getDivisor();
        });
        if (count($conflicts) > 0) {
            throw new \RuntimeException('Definition conflict!');
        }
        $this->definitions[] = $definition;
    }

    public function run(int $from = 0, int $to = 100)
    {
        for ($i = $from; $i <= $to; $i++) {
            $mask = $this->calculateBitmaskForInteger($i);
            echo $mask === 0
                ? $i
                : $this->calculateWords($mask);
            echo PHP_EOL;
        }
    }

    private function calculateBitmaskForInteger(int $number): int
    {
        $bitmask = 0;
        foreach (array_values($this->definitions) as $shift => $definition) {
            if ($number % $definition->getDivisor() === 0) {
                $bitmask = $bitmask | (1 << $shift);
            }
        }
        return $bitmask;
    }

    private function calculateWords(int $mask): string
    {
        $words = [];
        foreach ($this->definitions as $shift => $definition) {
            if ($mask & (1 << $shift)) {
                $words[] = $definition->getName();
            }
        }
        return implode(static::SEPARATOR, $words);
    }
}