numbered_list.py

import sublime_plugin
import re

class NumberListCommand(sublime_plugin.TextCommand):
	def run(self, edit):
		view = self.view
		sel = view.sel()[0]
		text = view.substr(view.full_line(sel))
		num = re.search('\d', text).start()
		dot = text.find(".")
		if num == 0:
			view.erase(edit, sel)
			view.insert(edit, sel.begin(), "\n%d. " % (int(text[:dot]) + 1,))
		else:
			view.erase(edit, sel)
			view.insert(edit, sel.begin(), "\n%s%d. " % (text[:num], int(text[num:dot]) + 1))

	def is_enabled(self):
		return bool(self.view.score_selector(self.view.sel()[0].a, "text.html.markdown"))