XF 2.0 Getting current context

i have extended \XF\Str\Formatter and \XF\BbCode\Renderer\Html. I am still not sure if i know what i am doing :)

I am overriding replaceSmiliesInText in Formatter and renderTagQuote in Html.

What i want is to get the Post that are beeing rendered/processed while in those functions. Anybody know if thats possible?
Trying to clarify a bit: I am trying to handle custom smilies but i need to know the post i am "working" on to be able to restrict and allow smilies depending on the poster.
Now i just get the text as input - is there a way to find the "current" post beeing parsed?