MarkdownParser.php

<?php
/*
 * Markdown Parser
 * Version 0.1.0
 * By Sam Thompson <http://openflame-project.org/>
 *
 * This code has hereby been released into the public domain
 * There's absolutely no warranty.
 *
 * This class works as a parser for Markdown, placing the data in an array to
 * be output to be futher manipulated as needed.
 */

class MarkdownParser
{
	/*
	 * @var raw
	 */
	public $raw = '';

	/*
	 * @var parsed array
	 */
	public $parsedText = array();

	/*
	 * @var linklist
	 */
	public $linkList = array();

	/*
	 * Constructor
	 */
	public function __construct($raw)
	{
		$this->raw = (string) $raw;
	}

	// Location flags
	const IN_PARAGRAPH	= 1;
	const IN_LIST		= 2;
	const IN_PREFORMAT	= 4;
	const IN_BLOCKQUOTE	= 8;

	// Types
	const TYPE_H1		= 'h1';
	const TYPE_H2		= 'h2';
	const TYPE_H3		= 'h3';
	const TYPE_H4		= 'h4';
	const TYPE_H5		= 'h5';
	const TYPE_H6		= 'h6';
	const TYPE_UL		= 'ul';
	const TYPE_OL		= 'ol';
	const TYPE_P		= 'p';
	const TYPE_BQ		= 'blockquote';
	const TYPE_PRE		= 'pre';
	const TYPE_CODE		= 'code';

	/*
	 * Parse
	 * @return void
	 */
	public function parse()
	{
		// Get rid of some annoyances then create an array
		$raw = str_replace(array("\r", "\t"), array("", "    "), $this->raw);
		$lines = explode("\n", $raw);

		$buffer = '';
		$flag = 0;
		$items = array();

		foreach($lines as $k => $line)
		{
			$prevLine = ($k - 1 < 0) ? null : $lines[$k - 1];

			// Code/preformated is always first
			if ($flag == self::IN_PREFORMAT || substr($line, 0, 3) == '```')
			{
				if (substr($line, 0, 3) == '```' && $flag != self::IN_PREFORMAT)
				{
					// Open the pre
					$flag = self::IN_PREFORMAT;
					$lang = substr(trim($line), 3);
					$buffer = ($lang == false) ? self::TYPE_PRE : self::TYPE_CODE;
				}
				else if(substr($line, 0, 3) == '```')
				{
					// Close the pre
					$this->parsedText[] = array('type' => $buffer, 'lang' => $lang, 'text' => implode("\n", $items));
					$flag = 0;
				}
				else
				{
					// append to pre
					$items[] = $line;
				}

				continue;
			}

			// Two line header
			if ($k > 0 && strlen($line) == strlen($prevLine) && $this->isHeader($line))
			{
				$type = ($line[0] == '=') ? $this->getHeading(1) : $this->getHeading(2);
				$this->parsedText[] = array('type' => $type, 'text' => $lines[$k-1]);
				continue;
			}

			// Is it an in-line header?
			if ($line[0] == '#')
			{
				for ($i = 0; $i < 6 && $line[$i] == '#'; $i++);
				$type = ($i > 6 || $i < 1) ? 1 : $i;

				$line = trim(str_replace(str_repeat('#', $i), '', $line));
				$this->parsedText[] = array('type' => $this->getHeading($type), 'text' => $line);
				continue;
			}

			// Lists (nasty regexp)
			if (preg_match("#^[\s]*[\(]*([0-9]+|\*|\-)[\)\.]*[\s]*([a-z0-9\[\]\(\)\,\.]{1}[a-z0-9\[\]\(\)\,\.\s]*)$#i", $line, $matches))
			{
				$flag = self::IN_LIST;
				$buffer = (is_numeric($matches[1])) ? self::TYPE_OL : self::TYPE_UL;
				$items[] = $matches[2];
			}

			// Blockquote
			if ($line[0] == '>')
			{
				$flag = self::IN_BLOCKQUOTE;
				$buffer .= trim(substr($line, 1)) . ' ';
				continue;
			}

			// Linklists
			if (preg_match("#^\[([0-9]+)\]: (.*)$#", $line, $matches) == 1)
			{
				$this->linkList[(int) $matches[1]] = trim($matches[2]);
				continue;
			}

			// Normal paragraph
			if (preg_match("#[a-z0-9_\-\.\,\s]+#i", $line) != 0 && ($prevLine === '' || $flag == self::IN_PARAGRAPH))
			{
				$flag = self::IN_PARAGRAPH;
				$buffer .= trim($line) . ' ';
				continue;
			}

			// This is a catch all, MUST BE LAST
			if (trim($line) === '')
			{
				switch ($flag)
				{
					case self::IN_PARAGRAPH:
						$this->parsedText[] = array('type' => self::TYPE_P, 'text' => $buffer);
					break;

					case self::IN_BLOCKQUOTE:
						$this->parsedText[] = array('type' => self::TYPE_BQ, 'text' => $buffer);
					break;

					case self::IN_LIST:
						$this->parsedText[] = array('type' => $buffer, 'items' => $items);
					break;
				}

				$flag = 0;
				$buffer = $lang = '';
				$items = array();
			}
		}
	}

	/*
	 * Checks to see if we had a header line this round
	 */
	private function isHeader($ln)
	{
		if($ln == str_repeat('=', strlen($ln)))
		{
			return true;
		}
		else if($ln == str_repeat('-', strlen($ln)))
		{
			return true;
		}

		return false;
	}

	public function getHeading($level)
	{
		switch($level)
		{
			case 1: return self::TYPE_H1; break;
			case 2: return self::TYPE_H2; break;
			case 3: return self::TYPE_H3; break;
			case 4: return self::TYPE_H4; break;
			case 5: return self::TYPE_H5; break;
			case 6: return self::TYPE_H6; break;
		}
	}
}

test.md

Heading 1

This is a test of stuff and other junk.

Block Quote for such a thing that would be a nice quote More of the blockquote

Google Is a website, and this is an inline style

Heading 2

• This is a list
• With items
• Item again
• yay items

Hello!

Below is a basic code example.

<?php
echo "Hello World!";
?>

You can see more crap in the OpenFlame Documentation

test.php

<?php

include 'MarkdownParser.php';

$text = new MarkdownParser(file_get_contents('test.md'));

echo "<pre>";

echo $text->raw;
echo "\n=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=\n";
$text->parse();

var_dump($text->parsedText);
echo "\n=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=\n";
var_dump($text->linkList);

echo "</pre>";

Just a note, this does not touch inline elements yet, working on the proper way to do that.