colorize.lua

   1 -- State transitions while colorizing a single line.
   2 -- Just for comments and strings.
   3 -- Limitation: each fragment gets a uniform color so we can only change color
   4 -- at word boundaries.
   5 Next_state = {
   6   normal={
   7     {prefix='--[[', target='block_comment'},  -- only single-line for now
   8     {prefix='--', target='comment'},
   9     -- these don't mostly work well until we can change color within words
  10     -- {prefix='"', target='dstring'},
  11     -- {prefix="'", target='sstring'},
  12     {prefix='[[', target='block_string'},  -- only single line for now
  13   },
  14   dstring={
  15     {suffix='"', target='normal'},
  16   },
  17   sstring={
  18     {suffix="'", target='normal'},
  19   },
  20   block_string={
  21     {suffix=']]', target='normal'},
  22   },
  23   block_comment={
  24     {suffix=']]', target='normal'},
  25   },
  26   -- comments are a sink
  27 }
  28
  29 Comment_color = {r=0, g=0, b=1}
  30 String_color = {r=0, g=0.5, b=0.5}
  31 Divider_color = {r=0.7, g=0.7, b=0.7}
  32
  33 Colors = {
  34   normal=Text_color,
  35   comment=Comment_color,
  36   sstring=String_color,
  37   dstring=String_color,
  38   block_string=String_color,
  39   block_comment=Comment_color,
  40 }
  41
  42 Current_state = 'normal'
  43
  44 function initialize_color()
  45 --?   print('new line')
  46   Current_state = 'normal'
  47 end
  48
  49 function select_color(frag)
  50 --?   print('before', '^'..frag..'$', Current_state)
  51   switch_color_based_on_prefix(frag)
  52 --?   print('using color', Current_state, Colors[Current_state])
  53   App.color(Colors[Current_state])
  54   switch_color_based_on_suffix(frag)
  55 --?   print('state after suffix', Current_state)
  56 end
  57
  58 function switch_color_based_on_prefix(frag)
  59   if Next_state[Current_state] == nil then
  60     return
  61   end
  62   frag = rtrim(frag)
  63   for _,edge in pairs(Next_state[Current_state]) do
  64     if edge.prefix and starts_with(frag, edge.prefix) then
  65       Current_state = edge.target
  66       break
  67     end
  68   end
  69 end
  70
  71 function switch_color_based_on_suffix(frag)
  72   if Next_state[Current_state] == nil then
  73     return
  74   end
  75   frag = rtrim(frag)
  76   for _,edge in pairs(Next_state[Current_state]) do
  77     if edge.suffix and ends_with(frag, edge.suffix) then
  78       Current_state = edge.target
  79       break
  80     end
  81   end
  82 end