GitHub markdown

[HarpyWar]

Hello, thanks for great implementation.

Is it possible to add full support of github markdown?
For example, tag ``` is ignored.

[jjok]

You should extend the Markdown class with a GithubMarkdown class, with the additional functionality, if you can.

[HarpyWar]

Could you please show me a sample code how to add a new tag, so I could start.

[michelf]

Code blocks are notoriously difficult to add because the HTML block parser needs to know how to avoid them. If you want to have an idea you can check how fenced code blocks (delimited by ~~~) are implemented in PHP Markdown Extra.

I don't intend to add Github-flavored fenced code blocks to PHP Markdown Extra, but having a third parser class for Github-flavored markdown could work.

[bmcminn]

I'm in favor of the GFM class extension, however I also find it's trivial to do this as-is with a simple regex modification.

On line #2770

<?php
  // change this
  ~{3,} # Marker: three tilde or more.

  // to this
  [~`]{3,} # Marker: three (tilde|acute|etc) or more.

It's overly simplistic, but I tested this yesterday and it works pretty well. The one caveat being if you use any combination of these characters of length 3+ (eg: ~``~~) it triggers, but I personally don't think that's a deal breaker.

My one suggestion may be to provide a code fence string config option for the MarkdownExtended object so that you can define what characters delineate a code fence.

[michelf]

@bmcminn It appears to work pretty well, but it'll break if you put HTML code inside. The HTML block parser needs to be aware of the syntax for it to work correctly, and because that's a somewhat perilous task (because it parses things very differently) it'd need a battery of tests. And the general way block-level elements are parsed needs to be revised rethought to avoid a couple of existing loopholes in that department.

Also, your proposed change would allow ridiculous things like ~~` as a marker.

[bmcminn]

I know it's not very structured in this approach, however I don't believe it's all that big an issue since I don't foresee anyone using ` as a their typical code fence.

Also, my use of this modification hasn't broken in regards to parsing HTML code inside a code fenced block. That was the first thing I tested and it rendered just fine. Although my markup snippet was fairly simple. So far since changing this one line I haven't noticed any breaking changes, however I do understand there is need for a more robust solution.

I still think allowing a user defined Class/Parser level config for the code fence string or even a REGEXP to be checked would be a considerable approach.

[michelf]

Merged pull #132. The feature is in HEAD now.