Как реализовать валидацию?

<?php
 
class ValidateIMG extends Validator {
 
    protected function validate() {
        $data = $this->data;
        if (!is_null($data) && !preg_match("/^[a-z0-9-_]+\.(jpg|jpeg|png|gif)$/i", $data)) $this->setError(self::CODE_UNKNOWN);
    }
}
 
?>

<?php
 
abstract class Validator {
 
    const CODE_UNKNOWN = "UNKNOWN_ERROR";
 
    protected $data;
    private $errors = array();
 
    public function validator($data) {
        $this->data = $data;
 
    }
 
    abstract protected function validate();
    
    public function getErrors() {
        return $this->errors;
    }
 
    protected function setError($code) {
        $this->errors[] = $code;
    }
 
    public function isValid() {
        return count($this->errors) == 0;
    }
    protected function isContainQuotes($string) {
        $array = array("\"", "'", "`", "&quot;", "&apos;");
        foreach ($array as $value) {
            //Ищем вхождение ковычек в $value
            if (strpos($string, $value) !== false) return true;
        }
        return false;
    }
}
 
 
?>

public static function input($table_name, $field, $where = false, $array_where = null, $operators = false) {
        $validate = new $validator();
        $validate->validator($field);
        $unswer = $validate->isValid();
        if ($unswer != 0) return false;
        else $function = $this->add($table_name, $field, $where = false, $array_where = null, $operators = false);
        return $function;
    }

$field = array('login' => 'validatetext', 'image' => 'validateimg');

$NewArray = array($key);

$fields = ['age' => 'required|integer|min:18'];

public function required($age) {
  return !empty($age);
}