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='comment'},
   8     {prefix='"', target='dstring'},
   9     {prefix="'", target='sstring'},
  10   },
  11   dstring={
  12     {suffix='"', target='normal'},
  13   },
  14   sstring={
  15     {suffix="'", target='normal'},
  16   },
  17   -- comments are a sink
  18 }
  19
  20 Comments_color = {r=0, g=0, b=1}
  21 String_color = {r=0, g=0.5, b=0.5}
  22 Divider_color = {r=0.7, g=0.7, b=0.7}
  23
  24 Colors = {
  25   normal=Text_color,
  26   comment=Comments_color,
  27   sstring=String_color,
  28   dstring=String_color
  29 }
  30
  31 Current_state = 'normal'
  32
  33 function initialize_color()
  34 --?   print('new line')
  35   Current_state = 'normal'
  36 end
  37
  38 function select_color(frag)
  39 --?   print('before', '^'..frag..'$', Current_state)
  40   switch_color_based_on_prefix(frag)
  41 --?   print('using color', Current_state, Colors[Current_state])
  42   App.color(Colors[Current_state])
  43   switch_color_based_on_suffix(frag)
  44 --?   print('state after suffix', Current_state)
  45 end
  46
  47 function switch_color_based_on_prefix(frag)
  48   if Next_state[Current_state] == nil then
  49     return
  50   end
  51   frag = rtrim(frag)
  52   for _,edge in pairs(Next_state[Current_state]) do
  53     if edge.prefix and find(frag, edge.prefix, nil, --[[plain]] true) == 1 then
  54       Current_state = edge.target
  55       break
  56     end
  57   end
  58 end
  59
  60 function switch_color_based_on_suffix(frag)
  61   if Next_state[Current_state] == nil then
  62     return
  63   end
  64   frag = rtrim(frag)
  65   for _,edge in pairs(Next_state[Current_state]) do
  66     if edge.suffix and rfind(frag, edge.suffix, nil, --[[plain]] true) == #frag then
  67       Current_state = edge.target
  68       break
  69     end
  70   end
  71 end
  72
  73 function trim(s)
  74   return s:gsub('^%s+', ''):gsub('%s+$', '')
  75 end
  76
  77 function ltrim(s)
  78   return s:gsub('^%s+', '')
  79 end
  80
  81 function rtrim(s)
  82   return s:gsub('%s+$', '')
  83 end