Added experimental request variable access class.

public/forum/forum.php

@@ -1,7 +1,10 @@
 <?php
+use Misuzu\Request\RequestVar;
+
 require_once '../../misuzu.php';
 
-$forumId = max((int)($_GET['f'] ?? 0), 0);
+$forumId = RequestVar::get()->select('f')->value('int');
+$forumId = max($forumId, 0);
 
 if ($forumId === 0) {
     header('Location: /forum/');

src/Request/RequestVar.php

@@ -0,0 +1,87 @@
+<?php
+ namespace Misuzu\Request;
+
+class RequestVar
+{
+    private $value;
+    private $valueCasted = null;
+    private $type;
+
+    protected function __construct($value, ?string $type = null)
+    {
+        $this->value = $value;
+        $this->type = $type ?? gettype($value);
+    }
+
+    public static function get(): RequestVar
+    {
+        return new static($_GET ?? []);
+    }
+
+    public static function post(): RequestVar
+    {
+        return new static($_POST ?? []);
+    }
+
+    public function __get(string $name)
+    {
+        return $this->select($name);
+    }
+
+    public function __isset(string $name): bool
+    {
+        switch ($this->type) {
+            case 'array':
+                return isset($this->value[$name]);
+
+            case 'object':
+                return isset($this->value->{$name});
+
+            default:
+                return null;
+        }
+    }
+
+    public function select(string $name): RequestVar
+    {
+        switch ($this->type) {
+            case 'array':
+                return new static($this->value[$name]);
+
+            case 'object':
+                return new static($this->value->{$name});
+
+            default:
+                return null;
+        }
+    }
+
+    public function value(string $type = 'string')
+    {
+        if (!is_null($this->valueCasted)) {
+            $this->valueCasted;
+        }
+
+        if ($this->type === 'NULL' || (($type === 'object' || $type === 'array') && $this->type !== $type)) {
+            return null;
+        }
+
+        if ($type !== 'string' && $this->type === 'string') {
+            switch ($type) {
+                case 'boolean':
+                case 'bool':
+                    return (bool)$this->value;
+                case 'integer':
+                case 'int':
+                    return (int)$this->value;
+                case 'double':
+                case 'float':
+                    return (float)$this->value;
+            }
+        } elseif ($type !== $this->type) {
+            return null;
+        }
+
+        return $this->valueCasted = $this->value;
+    }
+}