Support "-" (dash) in name of code block lang

Hi @gettalong,

are you going to accept a PR which makes it possible to use a dash in the code block language?

~~~ mermaid-graph
~~~

Maybe it's just this line which needs to be changed to

FENCED_CODEBLOCK_MATCH = /^((~){3,})\s*?(\w+-)?\s*?\n(.*?)^\1\2*\s*?\n/m

[gettalong]

Yes, I would accept it. I still have to have a look at the code to determine if this would have a side effect but I don't think so.

The change should be backwards-compatible because valid fenced code blocks are not affected.

[maxmeyer]

I opened a new PR using my private account.

[gettalong]

@maxmeyer Just one question before we go further: Wouldn't it be easier to just use an underscore instead of a dash in your custom language? Or is there another reason?

[maxmeyer]

Wouldn't it be easier to just use an underscore instead of a dash in your custom language?

To make it short: It's a reason for style and maybe compatibility with concurrent frameworks.

I would like to integrate mermaid into middleman-presentation via "code blocks":

~~~
graph TD;
A-->B;
A-->C;
B-->D;
C-->D;
~~~

I'm using a custom kramdown code block converter already so I'm able to generate the HTML stuff in a way I need.

Using code blocks raise a problem "for me": What if a user wants to highlight the mermaid code instead of rendering a graph? It looks like the guys over here decided to use something like this to make it possible:

~~~ mermaid-graph
graph TD;
A-->B;
A-->C;
B-->D;
C-->D;
~~~

Personally I like the mermaid-graph-thing because I use the dash as delimiter and the underscore where text belongs together but whitespace cannot be used: "20140101-this_is_a_text"

[maxmeyer]

BTW:
There seem to be some programming languages in the wild whose name include a dash. middleman-presentation depends on highlight.js for syntax highlighting. If the developers add one of those languages it could not be used with middleman-presentation. And as I'm very happy with kramdown, I don't want to switch the markdown-parser.

[gettalong]

Okay, thanks for explaining your reasons.

[gettalong]

Thanks for everything, your changes from #246 are now in master.