streamline version checking and active keys

In ripping out the source editor I also removed the ability to recover
from an unsupported version on a best-effort basis. Now the error
message matches that scenario.

app.lua

@@ -1,19 +1,13 @@
 App = {}
 App.screen = {}
 
-function App.love_version()
-  local major_version, minor_version = love.getVersion()
-  local version = major_version..'.'..minor_version
-  return version, major_version
-end
-
 function App.color(color)
   love.graphics.setColor(color.r, color.g, color.b, color.a)
 end
 
 nativefs = require 'nativefs'
 
-local Keys_down = {}
+Keys_down = {}
 for name in pairs(love.handlers) do
   -- love.keyboard.isDown doesn't work on Android, so emulate it using
   -- keypressed and keyreleased events
@@ -83,4 +77,3 @@ App.remove = nativefs.remove
 App.source_dir = love.filesystem.getSource()..'/'  -- '/' should work even on Windows
 App.current_dir = nativefs.getWorkingDirectory()..'/'
 App.save_dir = love.filesystem.getSaveDirectory()..'/'
-App.key_down = function(key) return Keys_down[key] end

array.lua

@@ -0,0 +1,28 @@
+array = {}
+
+function array.find(arr, elem)
+  if type(elem) == 'function' then
+    for i,x in ipairs(arr) do
+      if elem(x) then
+        return i
+      end
+    end
+  else
+    for i,x in ipairs(arr) do
+      if x == elem then
+        return i
+      end
+    end
+  end
+  return nil
+end
+
+function array.any(arr, f)
+  for i,x in ipairs(arr) do
+    local result = f(x)
+    if result then
+      return result
+    end
+  end
+  return false
+end

keychord.lua

@@ -8,53 +8,53 @@ function love.keypressed(key, scancode, isrepeat)
     return
   end
   -- include the modifier(s) when the non-modifer is pressed
-  love.keychord_pressed(App.combine_modifiers(key), key)
+  love.keychord_pressed(combine_modifiers(key), key)
 end
 
-function App.combine_modifiers(key)
+function combine_modifiers(key)
   if love.keyboard.isModifierActive then  -- waiting for LÖVE v12
     if key:match('^kp') then
-      key = App.translate_numlock(key)
+      key = translate_numlock(key)
     end
   end
   local result = ''
-  if App.ctrl_down() then
+  if ctrl_down() then
     result = result..'C-'
   end
-  if App.alt_down() then
+  if alt_down() then
     result = result..'M-'
   end
-  if App.shift_down() then
+  if shift_down() then
     result = result..'S-'  -- don't try to use this with letters/digits
   end
-  if App.cmd_down() then
+  if cmd_down() then
     result = result..'s-'
   end
   result = result..key
   return result
 end
 
-function App.any_modifier_down()
-  return App.ctrl_down() or App.alt_down() or App.shift_down() or App.cmd_down()
+function any_modifier_down()
+  return ctrl_down() or alt_down() or shift_down() or cmd_down()
 end
 
-function App.ctrl_down()
-  return App.key_down('lctrl') or App.key_down('rctrl')
+function ctrl_down()
+  return Keys_down.lctrl or Keys_down.rctrl
 end
 
-function App.alt_down()
-  return App.key_down('lalt') or App.key_down('ralt')
+function alt_down()
+  return Keys_down.lalt or Keys_down.ralt
 end
 
-function App.shift_down()
-  return App.key_down('lshift') or App.key_down('rshift')
+function shift_down()
+  return Keys_down.lshift or Keys_down.rshift
 end
 
-function App.cmd_down()
-  return App.key_down('lgui') or App.key_down('rgui')
+function cmd_down()
+  return Keys_down.lgui or Keys_down.rgui
 end
 
-function App.is_cursor_movement(key)
+function is_cursor_movement(key)
   return array.find({'left', 'right', 'up', 'down', 'home', 'end', 'pageup', 'pagedown'}, key)
 end
 
@@ -81,7 +81,7 @@ Numlock_on = {
   kpenter='enter',
   kpdel='delete',
 }
-function App.translate_numlock(key)
+function translate_numlock(key)
   if love.keyboard.isModifierActive('numlock') then
     return Numlock_on[key] or key
   else
@@ -89,32 +89,3 @@ function App.translate_numlock(key)
   end
   return key
 end
-
-array = {}
-
-function array.find(arr, elem)
-  if type(elem) == 'function' then
-    for i,x in ipairs(arr) do
-      if elem(x) then
-        return i
-      end
-    end
-  else
-    for i,x in ipairs(arr) do
-      if x == elem then
-        return i
-      end
-    end
-  end
-  return nil
-end
-
-function array.any(arr, f)
-  for i,x in ipairs(arr) do
-    local result = f(x)
-    if result then
-      return result
-    end
-  end
-  return false
-end

main.lua

@@ -5,12 +5,13 @@
 utf8 = require 'utf8'
 
 json = require('json')
-
-require('app')
+require('array')
 
 require('keychord')
 require('button')
 
+require('app')
+
 require('icons')
 require('drawing')
 require('geom')
@@ -25,7 +26,7 @@ require('select')
 require('undo')
 
 function love.load(arg)
-  Version, Major_version = App.love_version()
+  check_love_version()
 
   if love.filesystem.getInfo('config') then
     Settings = json.decode(love.filesystem.read('config'))
@@ -39,13 +40,21 @@ function love.load(arg)
   love.graphics.setBackgroundColor(1,1,1)
 
   run.initialize(arg)
+end
 
-  check_love_version()
+function check_love_version()
+  local supported_versions = {'11.5', '11.4', '12.0'}  -- put the recommended version first
+
+  local major_version, minor_version = love.getVersion()
+  local version = major_version..'.'..minor_version
+
+  if array.find(supported_versions, version) == nil then
+    error(
+      ("This app hasn't been tested with LÖVE version %s. Please add %s to `supported_versions` in main.lua to try it out, and switch to version %s if you run into issues."):format(version, version, supported_versions[1]))
+  end
 end
 
 function initialize_globals()
-  Supported_versions = {'11.5', '11.4', '12.0'}  -- put the recommended version first
-
   run.initialize_globals()
 
   -- for hysteresis in a few places
@@ -54,14 +63,6 @@ function initialize_globals()
   Last_resize_time = 0
 end
 
-function check_love_version()
-  if array.find(Supported_versions, Version) == nil then
-    error(
-      ("This app hasn't been tested with LÖVE version %s; please switch to version %s if you run into issues. Press any key to continue."):format(Version, Supported_versions[1]))
-    -- continue initializing everything; hopefully we won't have errors during initialization
-  end
-end
-
 function love.resize(w,h)
   if run.resize then run.resize(w,h) end
   Last_resize_time = Current_time

text.lua

@@ -122,8 +122,8 @@ end
 
 function Text.text_input(State, t)
   if love.mouse.isDown(1) then return end
-  if App.any_modifier_down() then
-    if App.key_down(t) then
+  if any_modifier_down() then
+    if Keys_down[t] then
       -- The modifiers didn't change the key. Handle it in keychord_pressed.
       return
     else