*** index.php ***
<?php 

include 'template.php';

$template = new Template();
$template->assign('username', 'Vuong');
$template->assign('age', '20');
$template->assign('favorite', 'KFC Chicken');
$template->render('myTemplate');

 ?>

*** template.php ***
<?php 

class Template
{
	private $vars = array();

	public function assign($key, $value){
		$this->vars[$key] = $value;
	}

	public function render($template_name){
		$path = $template_name . '.html';

		if(file_exists($path)){
			$contents = file_get_contents($path);
			
			foreach ($this->vars as $key => $value) {
				$contents = preg_replace('/\['. $key .'\]/', $value, $contents);
			}

			$contents = preg_replace('/\<\!\-\- if (.*) \-\-\>/', '<?php if ($1) : ?>', $contents);
			$contents = preg_replace('/\<\!\-\- else \-\-\>/', '<?php else : ?>', $contents);
			$contents = preg_replace('/\<\!\-\- endif \-\-\>/', '<?php endif; ?>', $contents);

			eval(' ?>'. $contents . '<?php ');
		} else{
			exit("Cannot find template $path");
		}
	}
}

 ?>

*** myTemplate.html ***
Hello, [username] is [age] years old and is favourite food is [favorite]!<br/><br/>

<!-- if 1 == 1 -->
	true
<!-- else -->
	false
<!-- endif -->