simple-array-iterator.php

<?php
/**
 * @author James Mannion <[email protected]>
 * @link https://www.jamse.net
 */
/**
 * Interface CarInterface
 */
interface CarInterface
{
    public function getYearOfManufacture() : int;
    public function getBrakeHorsePower() : int;
}
/**
 * Class Car
 */
class Car implements CarInterface
{
    private $yearOfManufacture;
    private $brakeHorsePower;
    
    public function __construct(int $yearOfManufacture, int $brakeHorsePower)
    {
        $this->yearOfManufacture = $yearOfManufacture;
        $this->brakeHorsePower = $brakeHorsePower;
    }
    /**
     * Year the car was manufactured
     *
     * @return int
     */
    public function getYearOfManufacture() : int
    {
        return $this->yearOfManufacture;
    }
    /**
     * Max brake horsepower
     *
     * @return int
     */
    public function getBrakeHorsePower() : int
    {
        return $this->brakeHorsePower;
    }
}
/**
 * (Abstract) collection of cars.
 * Class CarCollection
 */
abstract class CarCollection implements IteratorAggregate
{
    /** @var Car[]  */
    protected $cars = [];
    public function __construct($cars)
    {
        $this->cars = $cars;
    }
    /**
     * @return ArrayIterator
     */
    public function getIterator()
    {
        return new ArrayIterator($this->cars);
    }
    /**
     * Add a car to the collection
     *
     * @param Car $carToAdd
     */
    public function addCar(Car $carToAdd)
    {
        $this->cars[] = $carToAdd;
    }
    /**
     * Get a filtered SportsCarCollection of cars newer than a given year
     *
     * @param int $yearOfManufacture
     * @return CarCollection
     */
    public function newerThan(int $yearOfManufacture) : CarCollection
    {
        $cars = [];
        foreach ($this->cars as $car) {
            if($car->getYearOfManufacture() >= $yearOfManufacture) {
                $cars[] = $car;
            }
        }
        return new static($cars);
    }
}
/**
 * A collection of sports cars
 *
 * Class SportsCarCollection
 */
class SportsCarCollection extends CarCollection
{
    public function morePowerfulThan(int $brakeHorsePower) : SportsCarCollection
    {
        $cars = [];
        foreach ($this->cars as $car) {
            if($car->getBrakeHorsePower() >= $brakeHorsePower) {
                $cars[] = $car;
            }
        }
        return new static($cars);
    }
}
/** Create a collection of sports cars made in different years with different BHP */
$sportsCars = new SportsCarCollection(
    [
        new Car(1995, 300),
        new Car(1998, 450),
        new Car(2004, 500),
        new Car(1992, 400),
        new Car(1985, 190)
    ]
);
/**
 * Get and iterate over a list of sports cars built in or after 1995. Note that this behaviour is in the parent class.
 */
echo 'Modern sports cars:' . PHP_EOL;
$modernSportsCars = $sportsCars->newerThan(1995);
foreach ($modernSportsCars as $modernSportsCar) {
    var_dump($modernSportsCar);
}
/**
 * Get and iterate over a list of sports cars with 400BHP or more. Note that this behaviour is in the child class.
 */
echo 'Really powerful sports cars:' . PHP_EOL;
$lethalSportsCars = $sportsCars->morePowerfulThan(400);
foreach ($lethalSportsCars as $lethalSportsCar) {
    var_dump($lethalSportsCar);
}

A simple implementation of an ArrayIterator for a blog post.