Tokenizer

tokenizer.php

<?php

class Tokenizer {

	protected $tokenFormat = '[! %s !]'

	protected $rules = array();

	protected $raw;

	public function execute($input)
	{
		$this->raw = $input;

		foreach($this->rules as $token => $rule)
		{
			if($this->isClosable($token))
			{
				$search  = array($rule['open'], $rule['close']);
				$replace = array(
					sprintf($this->tokenFormat, 'OPEN_'.$token),
					sprintf($this->tokenFormat, 'CLOSE_'.$token),
				);
				$input   = preg_replace($search, $replace, $input);
			}
		}
	}

	protected function isClosable($token)
	{
		return isset($this->rules[$token]['close'];
	}

	protected function isNestable($key)
	{
		return isset($this->rules[$token]['nested']) and $this->rules[$key]['nested'];
	}
}

class Markdown {

	protected $rules = array(

		'EM' => array('open' => '\s_\S|\s\*\S'), 'close' => '\S_\s|\S\*\s'),
		'STRONG' => array('open' => '\s__\S|\s\*\*\S'), 'close' => '\S__\s|\S\*\*\s'),
		'EM_STRONG' =>array('open' => '\s___\S|\s\*\*\*\S'), 'close' => '\S___\s|\S\*\*\*\s'),
	);
}