3.10. Visitor¶

1<?php
2
3// Define the Shape interface
4interface Shape
5{
6    public function accept(ShapeVisitorInterface $visitor);
7}

 1<?php
 2
 3// Define the Circle class
 4class Circle implements Shape
 5{
 6    private $radius;
 7
 8    public function __construct($radius)
 9    {
10        $this->radius = $radius;
11    }
12
13    public function accept(ShapeVisitorInterface $visitor)
14    {
15        $visitor->visitCircle($this);
16    }
17
18    public function getRadius()
19    {
20        return $this->radius;
21    }
22}
23
24// Define the Square class
25class Square implements Shape
26{
27    private $length;
28
29    public function __construct($length)
30    {
31        $this->length = $length;
32    }
33
34    public function accept(ShapeVisitorInterface $visitor)
35    {
36        $visitor->visitSquare($this);
37    }
38
39    public function getLength()
40    {
41        return $this->length;
42    }
43}
44
45// Define the Rectangle class
46class Rectangle implements Shape
47{
48    private $width;
49    private $height;
50
51    public function __construct($width, $height)
52    {
53        $this->width = $width;
54        $this->height = $height;
55    }
56
57    public function accept(ShapeVisitorInterface $visitor)
58    {
59        $visitor->visitRectangle($this);
60    }
61
62    public function getWidth()
63    {
64        return $this->width;
65    }
66
67    public function getHeight()
68    {
69        return $this->height;
70    }
71}

 1<?php
 2
 3// Define the ShapeVisitor interface
 4interface ShapeVisitorInterface
 5{
 6    public function visitCircle(Circle $circle);
 7
 8    public function visitSquare(Square $square);
 9
10    public function visitRectangle(Rectangle $rectangle);
11}

 1<?php
 2
 3// Define the ShapeVisitor class
 4class ShapeVisitor implements ShapeVisitorInterface
 5{
 6    private $area;
 7    private $perimeter;
 8
 9    public function visitCircle(Circle $circle)
10    {
11        $this->area = pi() * $circle->getRadius() * $circle->getRadius();
12        $this->perimeter = 2 * pi() * $circle->getRadius();
13    }
14
15    public function visitSquare(Square $square)
16    {
17        $this->area = $square->getLength() * $square->getLength();
18        $this->perimeter = 4 * $square->getLength();
19    }
20
21    public function visitRectangle(Rectangle $rectangle)
22    {
23        $this->area = $rectangle->getWidth() * $rectangle->getHeight();
24        $this->perimeter = 2 * ($rectangle->getWidth() + $rectangle->getHeight());
25    }
26
27    public function getArea()
28    {
29        return $this->area;
30    }
31
32    public function getPerimeter()
33    {
34        return $this->perimeter;
35    }
36}

 1<?php
 2
 3// Example usage
 4$shapes = [
 5    new Circle(5),
 6    new Square(4),
 7    new Rectangle(3, 6),
 8];
 9
10// Create a new instance of the ShapeVisitor class
11$visitor = new ShapeVisitor();
12
13// Loop through each shape and call its accept() method, passing in the visitor object
14foreach ($shapes as $shape) {
15    $shape->accept($visitor);
16
17    echo get_class($shape) . " area is: " . $visitor->getArea() . ", perimeter is: " . $visitor->getPerimeter() . "\n";
18}