2.2. Мост (Bridge)

2.2.1. Назначение

Отделить абстракцию от её реализации так, что они могут изменяться независимо друг от друга.

2.2.2. Диаграмма UML

Alt Bridge UML Diagram

2.2.3. Код

Вы можете найти этот код на GitHub

Formatter.php

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<?php declare(strict_types=1);

namespace DesignPatterns\Structural\Bridge;

interface Formatter
{
    public function format(string $text): string;
}

PlainTextFormatter.php

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<?php declare(strict_types=1);

namespace DesignPatterns\Structural\Bridge;

class PlainTextFormatter implements Formatter
{
    public function format(string $text): string
    {
        return $text;
    }
}

HtmlFormatter.php

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<?php declare(strict_types=1);

namespace DesignPatterns\Structural\Bridge;

class HtmlFormatter implements Formatter
{
    public function format(string $text): string
    {
        return sprintf('<p>%s</p>', $text);
    }
}

Service.php

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<?php declare(strict_types=1);

namespace DesignPatterns\Structural\Bridge;

abstract class Service
{
    /**
     * @var Formatter
     */
    protected $implementation;

    /**
     * @param Formatter $printer
     */
    public function __construct(Formatter $printer)
    {
        $this->implementation = $printer;
    }

    /**
     * @param Formatter $printer
     */
    public function setImplementation(Formatter $printer)
    {
        $this->implementation = $printer;
    }

    abstract public function get(): string;
}

HelloWorldService.php

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<?php declare(strict_types=1);

namespace DesignPatterns\Structural\Bridge;

class HelloWorldService extends Service
{
    public function get(): string
    {
        return $this->implementation->format('Hello World');
    }
}

PingService.php

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<?php declare(strict_types=1);

namespace DesignPatterns\Structural\Bridge;

class PingService extends Service
{
    public function get(): string
    {
        return $this->implementation->format('pong');
    }
}

2.2.4. Тест

Tests/BridgeTest.php

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<?php declare(strict_types=1);

namespace DesignPatterns\Structural\Bridge\Tests;

use DesignPatterns\Structural\Bridge\HelloWorldService;
use DesignPatterns\Structural\Bridge\HtmlFormatter;
use DesignPatterns\Structural\Bridge\PlainTextFormatter;
use PHPUnit\Framework\TestCase;

class BridgeTest extends TestCase
{
    public function testCanPrintUsingThePlainTextFormatter()
    {
        $service = new HelloWorldService(new PlainTextFormatter());

        $this->assertSame('Hello World', $service->get());
    }

    public function testCanPrintUsingTheHtmlFormatter()
    {
        $service = new HelloWorldService(new HtmlFormatter());

        $this->assertSame('<p>Hello World</p>', $service->get());
    }
}