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PHP로 작성된 데코레이터
데코레이터는 구조 패턴이며 새로운 행동들을 특수 래퍼 객체들 내에 넣어서 이러한 행동들을 객체들에 동적으로 추가할 수 있도록 합니다.
데코레이터를 사용하여 객체들을 제한 없이 래핑할 수 있습니다. 왜냐하면 대상 객체들과 데코레이터들은 같은 인터페이스를 따르기 때문입니다. 결과 객체는 모든 래퍼의 스태킹된 행동을 가질 것입니다.
복잡도:
인기도:
사용 예시들: 데코레이터는 PHP 코드, 특히 스트림과 관련된 코드에서 꽤 표준적입니다.
식별: 데코레이터는 같은 클래스의 객체 또는 인터페이스를 현재 클래스로 수락하는 생성 메서드들 또는 생성자들로 인식할 수 있습니다.
개념적인 예시
이 예시는 데코레이터 패턴의 구조를 보여주고 다음 질문에 중점을 둡니다:
- 패턴은 어떤 클래스들로 구성되어 있나요?
- 이 클래스들은 어떤 역할을 하나요?
- 패턴의 요소들은 어떻게 서로 연관되어 있나요?
이 패턴의 구조를 배우면 실제 PHP 사용 사례를 기반으로 하는 다음 예시를 더욱 쉽게 이해할 수 있을 것입니다.
index.php: 개념적인 예시
<?php
namespace RefactoringGuru\Decorator\Conceptual;
/**
* The base Component interface defines operations that can be altered by
* decorators.
*/
interface Component
{
public function operation(): string;
}
/**
* Concrete Components provide default implementations of the operations. There
* might be several variations of these classes.
*/
class ConcreteComponent implements Component
{
public function operation(): string
{
return "ConcreteComponent";
}
}
/**
* The base Decorator class follows the same interface as the other components.
* The primary purpose of this class is to define the wrapping interface for all
* concrete decorators. The default implementation of the wrapping code might
* include a field for storing a wrapped component and the means to initialize
* it.
*/
class Decorator implements Component
{
/**
* @var Component
*/
protected $component;
public function __construct(Component $component)
{
$this->component = $component;
}
/**
* The Decorator delegates all work to the wrapped component.
*/
public function operation(): string
{
return $this->component->operation();
}
}
/**
* Concrete Decorators call the wrapped object and alter its result in some way.
*/
class ConcreteDecoratorA extends Decorator
{
/**
* Decorators may call parent implementation of the operation, instead of
* calling the wrapped object directly. This approach simplifies extension
* of decorator classes.
*/
public function operation(): string
{
return "ConcreteDecoratorA(" . parent::operation() . ")";
}
}
/**
* Decorators can execute their behavior either before or after the call to a
* wrapped object.
*/
class ConcreteDecoratorB extends Decorator
{
public function operation(): string
{
return "ConcreteDecoratorB(" . parent::operation() . ")";
}
}
/**
* The client code works with all objects using the Component interface. This
* way it can stay independent of the concrete classes of components it works
* with.
*/
function clientCode(Component $component)
{
// ...
echo "RESULT: " . $component->operation();
// ...
}
/**
* This way the client code can support both simple components...
*/
$simple = new ConcreteComponent();
echo "Client: I've got a simple component:\n";
clientCode($simple);
echo "\n\n";
/**
* ...as well as decorated ones.
*
* Note how decorators can wrap not only simple components but the other
* decorators as well.
*/
$decorator1 = new ConcreteDecoratorA($simple);
$decorator2 = new ConcreteDecoratorB($decorator1);
echo "Client: Now I've got a decorated component:\n";
clientCode($decorator2);
Output.txt: 실행 결과
Client: I've got a simple component:
RESULT: ConcreteComponent
Client: Now I've got a decorated component:
RESULT: ConcreteDecoratorB(ConcreteDecoratorA(ConcreteComponent))
실제 사례 예시
이 예시에서의 데코레이터 패턴은 웹 페이지에 콘텐츠를 렌더링하기 전에 해당 콘텐츠를 정리하기 위해 복잡한 텍스트 필터링 규칙을 생성하는 데 도움을 부여합니다. 댓글, 포럼 게시물 또는 비공개 메시지와 같은 다양한 유형의 콘텐츠에는 서로 다른 필터 집합들이 필요합니다.
예를 들어 댓글에서 모든 HTML을 제거하고 싶지만, 포럼 게시물에는 일부 기본 HTML 태그를 유지하고 싶을 수 있습니다. 또한 HTML 필터링이 발생하기 전에 처리되어야 하는 Markdown 형식의 게시를 허용할 수 있습니다. 이러한 모든 필터링 규칙은 별도의 데코레이터 클래스들로 표현될 수 있으며, 콘텐츠의 특성에 따라 다르게 스택될 수 있습니다.
index.php: 실제 사례 예시
<?php
namespace RefactoringGuru\Decorator\RealWorld;
/**
* The Component interface declares a filtering method that must be implemented
* by all concrete components and decorators.
*/
interface InputFormat
{
public function formatText(string $text): string;
}
/**
* The Concrete Component is a core element of decoration. It contains the
* original text, as is, without any filtering or formatting.
*/
class TextInput implements InputFormat
{
public function formatText(string $text): string
{
return $text;
}
}
/**
* The base Decorator class doesn't contain any real filtering or formatting
* logic. Its main purpose is to implement the basic decoration infrastructure:
* a field for storing a wrapped component or another decorator and the basic
* formatting method that delegates the work to the wrapped object. The real
* formatting job is done by subclasses.
*/
class TextFormat implements InputFormat
{
/**
* @var InputFormat
*/
protected $inputFormat;
public function __construct(InputFormat $inputFormat)
{
$this->inputFormat = $inputFormat;
}
/**
* Decorator delegates all work to a wrapped component.
*/
public function formatText(string $text): string
{
return $this->inputFormat->formatText($text);
}
}
/**
* This Concrete Decorator strips out all HTML tags from the given text.
*/
class PlainTextFilter extends TextFormat
{
public function formatText(string $text): string
{
$text = parent::formatText($text);
return strip_tags($text);
}
}
/**
* This Concrete Decorator strips only dangerous HTML tags and attributes that
* may lead to an XSS vulnerability.
*/
class DangerousHTMLTagsFilter extends TextFormat
{
private $dangerousTagPatterns = [
"|<script.*?>([\s\S]*)?</script>|i", // ...
];
private $dangerousAttributes = [
"onclick", "onkeypress", // ...
];
public function formatText(string $text): string
{
$text = parent::formatText($text);
foreach ($this->dangerousTagPatterns as $pattern) {
$text = preg_replace($pattern, '', $text);
}
foreach ($this->dangerousAttributes as $attribute) {
$text = preg_replace_callback('|<(.*?)>|', function ($matches) use ($attribute) {
$result = preg_replace("|$attribute=|i", '', $matches[1]);
return "<" . $result . ">";
}, $text);
}
return $text;
}
}
/**
* This Concrete Decorator provides a rudimentary Markdown → HTML conversion.
*/
class MarkdownFormat extends TextFormat
{
public function formatText(string $text): string
{
$text = parent::formatText($text);
// Format block elements.
$chunks = preg_split('|\n\n|', $text);
foreach ($chunks as &$chunk) {
// Format headers.
if (preg_match('|^#+|', $chunk)) {
$chunk = preg_replace_callback('|^(#+)(.*?)$|', function ($matches) {
$h = strlen($matches[1]);
return "<h$h>" . trim($matches[2]) . "</h$h>";
}, $chunk);
} // Format paragraphs.
else {
$chunk = "<p>$chunk</p>";
}
}
$text = implode("\n\n", $chunks);
// Format inline elements.
$text = preg_replace("|__(.*?)__|", '<strong>$1</strong>', $text);
$text = preg_replace("|\*\*(.*?)\*\*|", '<strong>$1</strong>', $text);
$text = preg_replace("|_(.*?)_|", '<em>$1</em>', $text);
$text = preg_replace("|\*(.*?)\*|", '<em>$1</em>', $text);
return $text;
}
}
/**
* The client code might be a part of a real website, which renders user-
* generated content. Since it works with formatters through the Component
* interface, it doesn't care whether it gets a simple component object or a
* decorated one.
*/
function displayCommentAsAWebsite(InputFormat $format, string $text)
{
// ..
echo $format->formatText($text);
// ..
}
/**
* Input formatters are very handy when dealing with user-generated content.
* Displaying such content "as is" could be very dangerous, especially when
* anonymous users can generate it (e.g. comments). Your website is not only
* risking getting tons of spammy links but may also be exposed to XSS attacks.
*/
$dangerousComment = <<<HERE
Hello! Nice blog post!
Please visit my <a href='http://www.iwillhackyou.com'>homepage</a>.
<script src="http://www.iwillhackyou.com/script.js">
performXSSAttack();
</script>
HERE;
/**
* Naive comment rendering (unsafe).
*/
$naiveInput = new TextInput();
echo "Website renders comments without filtering (unsafe):\n";
displayCommentAsAWebsite($naiveInput, $dangerousComment);
echo "\n\n\n";
/**
* Filtered comment rendering (safe).
*/
$filteredInput = new PlainTextFilter($naiveInput);
echo "Website renders comments after stripping all tags (safe):\n";
displayCommentAsAWebsite($filteredInput, $dangerousComment);
echo "\n\n\n";
/**
* Decorator allows stacking multiple input formats to get fine-grained control
* over the rendered content.
*/
$dangerousForumPost = <<<HERE
# Welcome
This is my first post on this **gorgeous** forum.
<script src="http://www.iwillhackyou.com/script.js">
performXSSAttack();
</script>
HERE;
/**
* Naive post rendering (unsafe, no formatting).
*/
$naiveInput = new TextInput();
echo "Website renders a forum post without filtering and formatting (unsafe, ugly):\n";
displayCommentAsAWebsite($naiveInput, $dangerousForumPost);
echo "\n\n\n";
/**
* Markdown formatter + filtering dangerous tags (safe, pretty).
*/
$text = new TextInput();
$markdown = new MarkdownFormat($text);
$filteredInput = new DangerousHTMLTagsFilter($markdown);
echo "Website renders a forum post after translating markdown markup" .
" and filtering some dangerous HTML tags and attributes (safe, pretty):\n";
displayCommentAsAWebsite($filteredInput, $dangerousForumPost);
echo "\n\n\n";
Output.txt: 실행 결과
Website renders comments without filtering (unsafe):
Hello! Nice blog post!
Please visit my <a href='http://www.iwillhackyou.com'>homepage</a>.
<script src="http://www.iwillhackyou.com/script.js">
performXSSAttack();
</script>
Website renders comments after stripping all tags (safe):
Hello! Nice blog post!
Please visit my homepage.
performXSSAttack();
Website renders a forum post without filtering and formatting (unsafe, ugly):
# Welcome
This is my first post on this **gorgeous** forum.
<script src="http://www.iwillhackyou.com/script.js">
performXSSAttack();
</script>
Website renders a forum post after translating markdown markupand filtering some dangerous HTML tags and attributes (safe, pretty):
<h1>Welcome</h1>
<p>This is my first post on this <strong>gorgeous</strong> forum.</p>
<p></p>
