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     {prefix='"', target='dstring'},
  10     {prefix="'", target='sstring'},
  11     {prefix='[[', target='block_string'},  -- only single line for now
  12   },
  13   dstring={
  14     {suffix='"', target='normal'},
  15   },
  16   sstring={
  17     {suffix="'", target='normal'},
  18   },
  19   block_string={
  20     {suffix=']]', target='normal'},
  21   },
  22   block_comment={
  23     {suffix=']]', target='normal'},
  24   },
  25   -- comments are a sink
  26 }
  27
  28 Comment_color = {r=0, g=0, b=1}
  29 String_color = {r=0, g=0.5, b=0.5}
  30 Divider_color = {r=0.7, g=0.7, b=0.7}
  31
  32 Colors = {
  33   normal=Text_color,
  34   comment=Comment_color,
  35   sstring=String_color,
  36   dstring=String_color,
  37   block_string=String_color,
  38   block_comment=Comment_color,
  39 }
  40
  41 Current_state = 'normal'
  42
  43 function initialize_color()
  44 --?   print('new line')
  45   Current_state = 'normal'
  46 end
  47
  48 function select_color(frag)
  49 --?   print('before', '^'..frag..'$', Current_state)
  50   switch_color_based_on_prefix(frag)
  51 --?   print('using color', Current_state, Colors[Current_state])
  52   App.color(Colors[Current_state])
  53   switch_color_based_on_suffix(frag)
  54 --?   print('state after suffix', Current_state)
  55 end
  56
  57 function switch_color_based_on_prefix(frag)
  58   if Next_state[Current_state] == nil then
  59     return
  60   end
  61   frag = rtrim(frag)
  62   for _,edge in pairs(Next_state[Current_state]) do
  63     if edge.prefix and find(frag, edge.prefix, nil, --[[plain]] true) == 1 then
  64       Current_state = edge.target
  65       break
  66     end
  67   end
  68 end
  69
  70 function switch_color_based_on_suffix(frag)
  71   if Next_state[Current_state] == nil then
  72     return
  73   end
  74   frag = rtrim(frag)
  75   for _,edge in pairs(Next_state[Current_state]) do
  76     if edge.suffix and rfind(frag, edge.suffix, nil, --[[plain]] true) == #frag - #edge.suffix + 1 then
  77       Current_state = edge.target
  78       break
  79     end
  80   end
  81 end
  82
  83 function trim(s)
  84   return s:gsub('^%s+', ''):gsub('%s+$', '')
  85 end
  86
  87 function ltrim(s)
  88   return s:gsub('^%s+', '')
  89 end
  90
  91 function rtrim(s)
  92   return s:gsub('%s+$', '')
  93 end