karlb / smu

smu - a Simple Markup Language
==============================

_smu_ is a very simple and minimal markup language. It is designed for use in
wiki-like environments. smu makes it very easy to write your documents on the
fly and convert them into HTML.

smu is capable of parsing very large documents. It scales just great as long
as you avoid a huge amount of indents.

Syntax
======

smu was started as a rewrite of
[markdown](http://daringfireball.net/projects/markdown/) but became something
more lightweight and consistent. It differs from [CommonMark](https://commonmark.org/) in the following ways:

* No support for _reference style links_
* Stricter indentation rules for lists
* Lists don't end paragraphs by themselves (blank line needed)
* Horizontal rules (`<hr>`) must use `- - -` as syntax
* Code fences have stricter syntax

Patches that increase the CommonMark compatibility are welcome as long as they don't increase the code complexity significantly.

This project is a fork of the [original smu](https://github.com/gottox/smu) by
[Enno Boland (gottox)](https://eboland.de). The main differences to the
original smu are:

* Support for code fences
* Improved [CommonMark](https://commonmark.org/) compatibility. E.g.
  * Code blocks need four spaces indentation instead of three
  * Skip empty lines at end of code blocks
  * Ignore single spaces around code spans
  * Keep HTML comments in output
  * Improved spec compliance for lists
  * Nesting code block in blockquotes works
  * "Empty" lines in lists behave identically, no matter how much whitespace they contain
  * No backslash escapes in code blocks
  * Use first number as start number for ordered lists
* Added a simple test suite to check for compliance and avoid regressions

Inline patterns
---------------

There are several patterns you can use to highlight your text:

* Emphasis
  * Surround your text with `*` or `_` to get *emphasised* text:
    	This *is* cool.
    	This _is_ cool, too.
  * Surround your text with `**` or `__` to get **strong** text:
    	This **is** cool.
    	This __is__ cool, too.
  * Surround your text with `***` or `___` to get ***strong and emphasised*** text:
    	This ***is*** cool.
    	This ___is___ cool, too.
  * But this example won't work as expected:
    	***Hello** you*
    This is a wontfix bug because it would make the source too complex.
    Use this instead:
    	***Hello*** *you*

* inline Code

  You can produce inline code by surrounding it with backticks.

  	Use `rm -rf /` if you're a N00b.
  	Use ``rm -rf /`` if you're a N00b.
  	Use ```rm -rf /``` if you're a N00b.

  Double and triple backticks can be used if the code itself contains backticks.


Titles
------

Creating titles in smu is very easy. There are two different syntax styles. The
first is underlining:

	Heading
	=======
	
	Topic
	-----

This is very intuitive and self explaining. The resulting sourcecode looks like
this:

	<h1>Heading</h1>
	<h2>Topic</h2>

Use the following prefixes if you don't like underlining:

	# h1
	## h2
	### h3
	#### h4
	##### h5
	###### h6

Links
-----

The simplest way to define a link is with simple `<>`.

	<http://s01.de>

You can do the same for E-Mail addresses:

	<[email protected]>

If you want to define a label for the url, you have to use a different syntax

	[smu - simple mark up](http://s01.de/~gottox/index.cgi/proj_smu)

The resulting HTML-Code

	<a href="http://s01.de/~gottox/index.cgi/proj_smu">smu - simple mark up</a></p>

Lists
-----

Defining lists is very straightforward:

	* Item 1
	* Item 2
	* Item 3

Result:

	<ul>
	<li>Item 1</li>
	<li>Item 2</li>
	<li>Item 3</li>
	</ul>

Defining ordered lists is also very easy:

	1. Item 1
	2. Item 2
	3. Item 3

Only the first number in a list is meaningful. All following list items are
continously counted. If you want a list starting at 2, you could write:

	2. Item 1
	2. Item 2
	2. Item 3

and get the following HTML which will render with the numbers 2, 3, 4:

	<ol start="2">
	<li>Item 1</li>
	<li>Item 2</li>
	<li>Item 3</li>
	</ol>

Code & Blockquote
-----------------

Use the `> ` as a line prefix for defining blockquotes. Blockquotes are
interpreted as well. This makes it possible to embed links, headings and even
other quotes into a quote:

	> Hello
	> This is a quote with a [link](http://s01.de/~gottox)

Result:
	<blockquote><p>
	Hello
	This is a quote with a <a href="http://s01.de/~gottox">link</a></p>
	</blockquote>


You can define a code block with a leading Tab or with __4__ leading spaces

		this.is(code)
	
	    this.is(code, too)

Result:
	<pre><code>this.is(code)</code></pre>
	<pre><code>this.is(code, too)
	</code></pre>

Please note that you can't use HTML or smu syntax in a code block.

Another way to write code blocks is to use code fences:

	```json
	{"some": "code"}
	```

This has two advantages:
* The optional language identifier will be turned into a `language-` class name
* You can keep the original indentation which helps when doing copy & paste

Other interesting stuff
-----------------------

* to insert a horizontal rule simple add `- - -` into an empty line:

  	Hello
  	- - -
  	Hello2

  Result:
  	<p>
  	Hello
  	<hr />
  	
  	Hello2</p>

* Any ASCII punctuation character may escaped by precedeing them with a
  backslash to avoid them being interpreted:

  	!"#$%&'()*+,-./:;<=>?@[]^_`{|}~\

* To force a linebreak simple add two spaces to the end of the line:

  	No linebreak
  	here.
  	But here is  
  	one.

embed HTML
----------

You can include arbitrary HTML code in your documents. The HTML will be
passed through to the resulting document without modification. This is a good
way to work around features that are missing in smu. If you don't want this
behaviour, use the `-n` flag when executing smu to stricly escape the HTML
tags.