オブジェクト指向っぽくFizzBuzzを解いてみる。

FizzBuzz.php

<?php

class FizzBuzz
{
    private $n;

    private $fizzSpec;
    private $buzzSpec;
    private $noFizzBuzzSpec;

    public function __construct($n)
    {
        $this->n = (int)$n;
        $this->fizzSpec       = new FizzSpecification();
        $this->buzzSpec       = new BuzzSpecification();
        $this->noFizzBuzzSpec = new NoFizzBuzzSpecification();
    }

    public function getN()
    {
        return $this->n;
    }

    public function toString()
    {
        if ($this->noFizzBuzzSpec->isSatisfiedBy($this)) return (string)$this->n;

        $isFizz = $this->fizzSpec->isSatisfiedBy($this);
        $fizz = Fizz::getInstance($isFizz);
        $isBuzz = $this->buzzSpec->isSatisfiedBy($this);
        $buzz = Buzz::getInstance($isBuzz);

        return $fizz->toString() . $buzz->toString();
    }
}

interface SpecificationInterface
{
    function isSatisfiedBy(FizzBuzz $fizzbuzz);
}

class FizzSpecification implements SpecificationInterface
{
    function isSatisfiedBy(FizzBuzz $fizzbuzz)
    {
        return $fizzbuzz->getN() % 3 === 0;
    }
}

class BuzzSpecification implements SpecificationInterface
{
    function isSatisfiedBy(FizzBuzz $fizzbuzz)
    {
        return $fizzbuzz->getN() % 5 === 0;
    }
}

class NoFizzBuzzSpecification implements SpecificationInterface
{
    function isSatisfiedBy(FizzBuzz $fizzbuzz)
    {
        $fizzSpec = new FizzSpecification();
        $buzzSpec = new BuzzSpecification();
        return !$fizzSpec->isSatisfiedBy($fizzbuzz) && !$buzzSpec->isSatisfiedBy($fizzbuzz);
    }
}

interface FizzBuzzInterface
{
    public function toString();
}

class Fizz implements FizzBuzzInterface
{
    public static function getInstance($isFizz)
    {
        return $isFizz ? new Fizz() : new NullFizz();
    }

    public function toString()
    {
        return "Fizz";
    }
}

class NullFizz extends Fizz
{
    public function toString()
    {
        return "";
    }
}

class Buzz implements FizzBuzzInterface
{
    public static function getInstance($isBuzz)
    {
        return $isBuzz ? new Buzz() : new NullBuzz();
    }

    public function toString()
    {
        return "Buzz";
    }
}

class NullBuzz extends Buzz
{
    public function toString()
    {
        return "";
    }
}

$fizzbuzz = array();
for ($i = 1; $i <= 20; $i++) {
    $fizzbuzz[$i] = new FizzBuzz($i);
    echo sprintf("FizzBuzz(%d) = %s\n", $i, $fizzbuzz[$i]->toString());
}