Sublime Text 2 FelixCalculatorCommand { "keys": ["alt+c"], "command": "felix_calculator" }

felixcalc.py

import sublime, sublime_plugin
from math import *

class FelixCalculatorCommand(sublime_plugin.TextCommand):

  def run(self, edit):
    window = self.view.window()
    window.show_input_panel('Enter operation and operand (e.g. +i, +20, sqrt(x), -, =):', '',
                            self.on_done, None, None)

  def on_done(self, input_text):
    edit = self.view.begin_edit('Felix Calculation')
    try:
      i = -1
      for sel in self.view.sel():
        i += 1
        selection_text = self.view.substr(sel)
        result = None
        if len(input_text) == 1:  # replace selection by line of input_text
          result = input_text * len(selection_text)
        elif 'x' in input_text:  # x is replaced by selection, then evaluated
          expr = input_text.replace('x', selection_text)
        else:  # evaluate '(<selection>) <input>' (e.g. sel='2', inp='*3' yields '(2) *3' => '6')
          expr = ('(%s) ' % selection_text) + input_text
        if result is None:
          try:
            result = eval(expr)
          except:
            continue
        self.view.replace(edit, sel, str(result))
    finally:
      self.view.end_edit(edit)