Adapter

Adapter

To translate one interface for a class into a compatible interface. An adapter allows classes to work together that normally could not because of incompatible interfaces by providing its interface to clients while using the original interface.

UML

Code

Book.php

<?php

namespace Kuriv\PHPDesignPatterns\Structural\Adapter;

interface Book
{
    /**
     * Open a book.
     *
     * @param  void
     * @return void
     */
    public function open();

    /**
     * Turn to the next page.
     *
     * @param  void
     * @return void
     */
    public function turnPage();

    /**
     * Get the current page.
     *
     * @param  void
     * @return int
     */
    public function getPage(): int;
}

TextBook.php

<?php

namespace Kuriv\PHPDesignPatterns\Structural\Adapter;

class TextBook implements Book
{
    /**
     * Current page.
     *
     * @var int
     */
    private int $page;

    /**
     * Open a book.
     *
     * @param  void
     * @return void
     */
    public function open()
    {
        $this->page = 1;
    }

    /**
     * Turn to the next page.
     *
     * @param  void
     * @return void
     */
    public function turnPage()
    {
        $this->page++;
    }

    /**
     * Get the current page.
     *
     * @param  void
     * @return int
     */
    public function getPage(): int
    {
        return $this->page;
    }
}

EBook.php

<?php

namespace Kuriv\PHPDesignPatterns\Structural\Adapter;

interface EBook
{
    /**
     * Unlock the screen.
     *
     * @param  void
     * @return void
     */
    public function unlock();

    /**
     * Press the next page.
     *
     * @param  void
     * @return void
     */
    public function pressNext();

    /**
     * Get the current page and total number of pages, like [10, 100].
     *
     * @param  void
     * @return array
     */
    public function getPage(): array;
}

Kindle.php

<?php

namespace Kuriv\PHPDesignPatterns\Structural\Adapter;

class Kindle implements EBook
{
    /**
     * Current page.
     *
     * @var int
     */
    private int $page;

    /**
     * Total pages.
     *
     * @var int
     */
    private int $totalPages;

    /**
     * Unlock the screen.
     *
     * @param  void
     * @return void
     */
    public function unlock()
    {
        $this->page = 1;
        $this->totalPages = 100;
    }

    /**
     * Press the next page.
     *
     * @param  void
     * @return void
     */
    public function pressNext()
    {
        $this->page++;
    }

    /**
     * Get the current page and total number of pages, like [10, 100].
     *
     * @param  void
     * @return array
     */
    public function getPage(): array
    {
        return [$this->page, $this->totalPages];
    }
}

EBookAdapter.php

<?php

namespace Kuriv\PHPDesignPatterns\Structural\Adapter;

class EBookAdapter implements Book
{
    /**
     * Instance that needs to be adapted.
     *
     * @var EBook
     */
    private EBook $instance;

    /**
     * Save the instance that needs to be adapted.
     *
     * @param  EBook $instance
     * @return void
     */
    public function __construct(EBook $instance)
    {
        $this->instance = $instance;
    }

    /**
     * Open a book.
     *
     * @param  void
     * @return void
     */
    public function open()
    {
        $this->instance->unlock();
    }

    /**
     * Turn to the next page.
     *
     * @param  void
     * @return void
     */
    public function turnPage()
    {
        $this->instance->pressNext();
    }

    /**
     * Get the current page.
     *
     * @param  void
     * @return int
     */
    public function getPage(): int
    {
        return $this->instance->getPage()[0];
    }
}

Test

AdapterTest.php

<?php

namespace Kuriv\PHPDesignPatterns\Structural\Adapter;

use PHPUnit\Framework\TestCase;

class AdapterTest extends TestCase
{
    public function testCanTurnPageOnTextBook()
    {
        $textbook = new TextBook();
        $textbook->open();
        $textbook->turnPage();
        $this->assertSame(2, $textbook->getPage());
    }

    public function testCanTurnPageOnKindleLikeInANormalTextBook()
    {
        $kindle = new EBookAdapter(new Kindle());
        $kindle->open();
        $kindle->turnPage();
        $this->assertSame(2, $kindle->getPage());
    }
}