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 but became something more lightweight and consistent. It differs from CommonMark 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 by Enno Boland (gottox). The main differences to the original smu are:

Support for code fences
Improved CommonMark 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 with at least three characters:

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:

<yourname@s01.de>

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>

Images

Images use a syntax similar to the one for links:

![optional alt text](http://example.com/image.png)

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

Tables

Tables can be generated with the following syntax:

| Heading1 | Heading2 |
| -------- | -------- |
| Cell 1   | Cell2    |

Aligning the columns make the input nicer to read, but is not necessary to get correct table output. You could just write

| Heading1 | Heading2 |
| --- | --- |
| Cell 1 | Cell2 |

To align the content of table cells, use |:--| for left, |--:| for right and |:--:| for centered alignment in the row which separates the header from the table body.

| Heading1 | Heading2 | Heading3 |
| :------- | :------: | -------: |
| Left     | Center   | Right    |

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.
```
Text wrapped in $ or $$ is not processed so it can be used with MathJax

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.