What application code language are you using that doesn't already have one or more source doc-generators? Can you just tweak or post process the output from them?

shell? Something like this (definitely buggy; you’ll have to remove the ‘$’ from the line before you evaluate it. I also didn’t check how to match that dollar sign at the start of a line. I think you can solve both problems by using a semicolon, not a dollar sign as indicator for ‘evaluate this line’. You also _may_ want to allow multi-line commands and there maybe more bugs):

  while read line ; do
    case "$line" in
      \$*) `$line`
      *)  echo $line
      ;;
    esac
  done