PHP7 Visitor

Author: domnikl

Behavioral/README.md

@@ -2,29 +2,25 @@
 
 namespace DesignPatterns\Behavioral\Visitor;
 
-/**
- * An example of a Visitor: Group.
- */
-class Group extends Role
+class Group implements Role
 {
     /**
      * @var string
      */
-    protected $name;
+    private $name;
 
-    /**
-     * @param string $name
-     */
-    public function __construct($name)
+    public function __construct(string $name)
     {
-        $this->name = (string) $name;
+        $this->name = $name;
     }
 
-    /**
-     * @return string
-     */
-    public function getName()
+    public function getName(): string
+    {
+        return sprintf('Group: %s', $this->name);
+    }
+
+    public function accept(RoleVisitorInterface $visitor)
     {
-        return 'Group: '.$this->name;
+        $visitor->visitGroup($this);
     }
 }

Behavioral/Visitor/Group.php

@@ -31,9 +31,9 @@ RoleVisitorInterface.php
    :language: php
    :linenos:
 
-RolePrintVisitor.php
+RoleVisitor.php
 
-.. literalinclude:: RolePrintVisitor.php
+.. literalinclude:: RoleVisitor.php
    :language: php
    :linenos:
 

Behavioral/Visitor/README.rst

@@ -2,32 +2,7 @@
 
 namespace DesignPatterns\Behavioral\Visitor;
 
-/**
- * class Role.
- */
-abstract class Role
+interface Role
 {
-    /**
-     * This method handles a double dispatch based on the short name of the Visitor.
-     *
-     * Feel free to override it if your object must call another visiting behavior
-     *
-     * @param \DesignPatterns\Behavioral\Visitor\RoleVisitorInterface $visitor
-     *
-     * @throws \InvalidArgumentException
-     */
-    public function accept(RoleVisitorInterface $visitor)
-    {
-        // this trick to simulate double-dispatch based on type-hinting
-        $klass = get_called_class();
-        preg_match('#([^\\\\]+)$#', $klass, $extract);
-        $visitingMethod = 'visit'.$extract[1];
-
-        // this ensures strong typing with visitor interface, not some visitor objects
-        if (!method_exists(__NAMESPACE__.'\RoleVisitorInterface', $visitingMethod)) {
-            throw new \InvalidArgumentException("The visitor you provide cannot visit a $klass instance");
-        }
-
-        call_user_func(array($visitor, $visitingMethod), $this);
-    }
+    public function accept(RoleVisitorInterface $visitor);
 }

Behavioral/Visitor/Role.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace DesignPatterns\Behavioral\Visitor;
+
+class RoleVisitor implements RoleVisitorInterface
+{
+    /**
+     * @var Role[]
+     */
+    private $visited = [];
+
+    public function visitGroup(Group $role)
+    {
+        $this->visited[] = $role;
+    }
+
+    public function visitUser(User $role)
+    {
+        $this->visited[] = $role;
+    }
+
+    /**
+     * @return Role[]
+     */
+    public function getVisited(): array
+    {
+        return $this->visited;
+    }
+}

Behavioral/Visitor/RolePrintVisitor.php

@@ -3,29 +3,12 @@
 namespace DesignPatterns\Behavioral\Visitor;
 
 /**
- * Visitor Pattern.
- *
- * The contract for the visitor.
- *
- * Note 1 : in C++ or Java, with method polymorphism based on type-hint, there are many
- * methods visit() with different type for the 'role' parameter.
- *
- * Note 2 : the visitor must not choose itself which method to
- * invoke, it is the Visitee that make this decision.
+ * Note: the visitor must not choose itself which method to
+ * invoke, it is the Visitee that make this decision
  */
 interface RoleVisitorInterface
 {
-    /**
-     * Visit a User object.
-     *
-     * @param \DesignPatterns\Behavioral\Visitor\User $role
-     */
     public function visitUser(User $role);
 
-    /**
-     * Visit a Group object.
-     *
-     * @param \DesignPatterns\Behavioral\Visitor\Group $role
-     */
     public function visitGroup(Group $role);
 }

Behavioral/Visitor/RoleVisitor.php

@@ -4,42 +4,34 @@
 
 use DesignPatterns\Behavioral\Visitor;
 
-/**
- * VisitorTest tests the visitor pattern.
- */
 class VisitorTest extends \PHPUnit_Framework_TestCase
 {
-    protected $visitor;
+    /**
+     * @var Visitor\RoleVisitor
+     */
+    private $visitor;
 
     protected function setUp()
     {
-        $this->visitor = new Visitor\RolePrintVisitor();
+        $this->visitor = new Visitor\RoleVisitor();
     }
 
-    public function getRole()
+    public function provideRoles()
     {
-        return array(
-            array(new Visitor\User('Dominik'), 'Role: User Dominik'),
-            array(new Visitor\Group('Administrators'), 'Role: Group: Administrators'),
-        );
+        return [
+            [new Visitor\User('Dominik')],
+            [new Visitor\Group('Administrators')],
+        ];
     }
 
     /**
-     * @dataProvider getRole
+     * @dataProvider provideRoles
+     *
+     * @param Visitor\Role $role
      */
-    public function testVisitSomeRole(Visitor\Role $role, $expect)
+    public function testVisitSomeRole(Visitor\Role $role)
     {
-        $this->expectOutputString($expect);
         $role->accept($this->visitor);
-    }
-
-    /**
-     * @expectedException \InvalidArgumentException
-     * @expectedExceptionMessage Mock
-     */
-    public function testUnknownObject()
-    {
-        $mock = $this->getMockForAbstractClass('DesignPatterns\Behavioral\Visitor\Role');
-        $mock->accept($this->visitor);
+        $this->assertSame($role, $this->visitor->getVisited()[0]);
     }
 }

Behavioral/Visitor/RoleVisitorInterface.php

@@ -2,31 +2,25 @@
 
 namespace DesignPatterns\Behavioral\Visitor;
 
-/**
- * Visitor Pattern.
- *
- * One example for a visitee. Each visitee has to extends Role
- */
-class User extends Role
+class User implements Role
 {
     /**
      * @var string
      */
-    protected $name;
+    private $name;
 
-    /**
-     * @param string $name
-     */
-    public function __construct($name)
+    public function __construct(string $name)
     {
-        $this->name = (string) $name;
+        $this->name = $name;
     }
 
-    /**
-     * @return string
-     */
-    public function getName()
+    public function getName(): string
+    {
+        return sprintf('User %s', $this->name);
+    }
+
+    public function accept(RoleVisitorInterface $visitor)
     {
-        return 'User '.$this->name;
+        $visitor->visitUser($this);
     }
 }