Custom language handlers

The Gollum API allows defining custom behavior for rendering codeblocks for specific languages. The rendering of Mermaid diagrams is implemented in this way and may serve as an example:

Gollum::Filter::Code.language_handlers[/mermaid/] = Proc.new { |lang, code| "<div class=\"mermaid\">\n#{code}\n</div>" }

This snippet ensures that code blocks that define their language as mermaid...

```mermaid

...will be rendered as the div returned by the Proc.

The language definition (the string after the triple backticks) must match the regular expression in Gollum::Filter::Code.language_handlers[regex] for the Proc to be called.

The Proc is passed two arguments: the String language of the codeblock, and its contents.

You can add a custom language handler to your config.rb, so there's no need to alter Gollum's source code.