Experiment with DOM as markup widget generation

widgettest.php

<?php

abstract class Widget
{
	const
		TYPE		= '';
	
	protected
		/**
		 * @var DOMDocument 
		 */
		$dom		= NULL,
		
		/**
		 * @var DOMElement
		 */
		$node		= NULL,
		
		/**
		 * @var array 
		 */
		$classes	= array (),
		
		/**
		 * @var string 
		 */
		$elemName	= '';
	/**
	 * Get the element node
	 * 
	 * @return DOMElement 
	 */
	
	public function getNode ()
	{
		if ($this -> node === NULL)
		{
			$this -> node = new DOMElement (static::TYPE);
			$this -> dom -> appendChild ($this -> node);
		}
		return $this -> node;
	}
	
	/**
	 * Check if the element node has been initialized
	 * 
	 * @return bool 
	 */
	protected function nodeInitialized ()
	{
		return $this -> node !== NULL;
	}
	
	/**
	 * Set an ID for the element
	 * 
	 * @param string $id
	 * @return \FormWidget
	 * @throws InvalidArgumentException 
	 */
	public function setId ($id)
	{
		if (is_string ($id))
		{
			$this -> elemId	= $id;
			!empty ($id)?
				$this -> getNode () -> setAttribute ('id', $id):
				$this -> getNode () -> removeAttribute ('id');
		}
		else
		{
			throw new InvalidArgumentException ();
		}
		return $this;
	}
	/**
	 * Add a class to the element
	 * 
	 * @param type $class
	 * @return \FormWidget
	 * @throws InvalidArgumentException 
	 */
	public function addClass ($class)
	{
		if (is_string ($class))
		{
			if (!in_array ($class, $this -> classes))
			{
				$this -> classes []	= $class;
				$this -> getNode () -> setAttribute ('class', implode (' ', $this -> classes));
			}
		}
		else
		{
			throw new InvalidArgumentException ();
		}
		return $this;
	}
	
	/**
	 * Constructor
	 * 
	 * @param DOMDocument $dom 
	 */
	public function __construct (DOMDocument $dom)
	{
		$this -> dom	= $dom;
	}
	
	/**
	 * Cast to string
	 * 
	 * @return string 
	 */
	public function __toString ()
	{
		return $this -> dom -> saveHTML ($this -> getNode ());
	}
}

/**
 * Form widget class 
 */
abstract class FormWidget extends Widget
{
	protected
		
		/**
		 * @var string 
		 */
		$elemId		= '';
	
	/**
	 * Set the name for the element
	 * 
	 * @param string $name
	 * @return \FormWidget
	 * @throws InvalidArgumentException 
	 */
	public function setName ($name)
	{
		if (is_string ($name))
		{
			$this -> elemName	= $name;
			!empty ($name)?
				$this -> getNode () -> setAttribute ('name', $name):
				$this -> getNode () -> removeAttribute ('name');
		}
		else
		{
			throw new InvalidArgumentException ();
		}
		return $this;
	}
}

/**
 * Form inputs (input tag)
 */
class InputWidget extends FormWidget
{
	const
		TYPE	= 'input';
	
	protected
		$value	= '';
	
	/**
	 * Set the value for the widget
	 * 
	 * @param type $value
	 * @return \InputWidget
	 * @throws InvalidArgumentException 
	 */
	public function setValue ($value)
	{
		if (is_string ($value))
		{
			$this -> value	= $value;
			!empty ($value)?
				$this -> getNode () -> setAttribute ('value', $value):
				$this -> getNode () -> removeAttribute ('value');
		}
		else
		{
			throw new InvalidArgumentException ();
		}
		return $this;
	}
}

/**
 * Text widget (input type=text) 
 */
class TextWidget extends InputWidget
{
	/**
	 * Get the input element
	 * 
	 * @return type 
	 */
	public function getNode ()
	{
		$initialized	= $this -> nodeInitialized ();
		$node			= parent::getNode ();
		
		if (!$initialized)
		{
			$node -> setAttribute ('type', 'text');
		}
		
		return $node;
	}
}

/**
 * Select widget 
 */
class SelectWidget extends FormWidget
{
	const
		TYPE	= 'select';
}

/**
 * Textarea widget 
 */
class TextAreaWidget extends FormWidget
{
	const
		TYPE	= 'textarea';
}

/**
 * Button widget 
 */
class ButtonWidget extends FormWidget
{
	const
		TYPE	= 'button';
}

$dom	= new DOMDocument ();
$test	= new TextWidget ($dom);
$test	-> setId ('thisId')
		-> setName ('thisName')
		-> addClass ('foo')
		-> addClass ('bar')
		-> addClass ('baz');

$test2	= new TextWidget ($dom);
$test2	-> setId ('thatId')
		-> setName ('thisName')
		-> addClass ('fred')
		-> addClass ('wilma')
		-> addClass ('pebbles');

?>
<!--
To change this template, choose Tools | Templates
and open the template in the editor.
-->
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title></title>
    </head>
    <body>
		<?php 
		echo $test . PHP_EOL 
			. $test . PHP_EOL
			. $test . PHP_EOL
			. $test2 . PHP_EOL
			. $test2 . PHP_EOL
			. $test2 . PHP_EOL; 
		?>
    </body>
</html>