avoid conditional on critical path w/o self-modification

When displaying the source code of an existing function, the :function
command will respect settings such as 'listchars' which makes the
recompilation code fragile. (I could research all the settings that
affect the output in such a way it can no longer be :execute’d and add
code to save, reset and restore them, but even if the list of settings
is comprehensive now, more such settings may get added to Vim in the
future. Therefore it is preferrable to circumstep the issue entirely.)

after/syntax/css.vim

@@ -10,8 +10,8 @@ for i in range(0, 255)
   let s:hex[ printf( '%02x', i ) ] = i
 endfor
 
-let s:black = '000000'
-let s:white = 'ffffff'
+let s:black = '#000000'
+let s:white = '#ffffff'
 
 function! s:FGForBG(color)
   " pick suitable text color given a background color
@@ -22,6 +22,9 @@ function! s:FGForBG(color)
   return r*30 + g*59 + b*11 > 12000 ? s:black : s:white
 endfunction
 
+let s:color_prefix  = 'gui'
+let s:fg_color_calc = 'let color = "#" . a:color'
+
 function! s:MatchColorValue(color, pattern)
   if ! len(a:color) | return | endif
   let group = 'cssColor' . tolower(a:color)
@@ -33,7 +36,8 @@ function! s:MatchColorValue(color, pattern)
   if stridx( currentmatch, 'match /'.pattern.'/' ) >= 0 | return '' | endif
   exe 'syn match' group '/'.pattern.'/ contained'
   exe 'syn cluster cssColors add='.group
-  exe 'hi' group 'ctermbg='.s:XTermColorForRGB(a:color) 'ctermfg='.s:FGForBG(a:color)
+  exe s:fg_color_calc
+  exe 'hi' group s:color_prefix.'bg='.color s:color_prefix.'fg='.s:FGForBG(a:color)
   return ''
 endfunction
 
@@ -94,6 +98,12 @@ if has("gui_running") || &t_Co==256
 
   if ! has('gui_running')
 
+    let s:black = 0
+    let s:white = 15
+
+    let s:color_prefix  = 'cterm'
+    let s:fg_color_calc = 'let color = s:XTermColorForRGB(a:color)'
+
     " preset 16 vt100 colors
     let s:xtermcolor = [
       \ [ 0x00, 0x00, 0x00,  0 ],
@@ -140,9 +150,6 @@ if has("gui_running") || &t_Co==256
       \ [ 0xE4, 0xE4, 0xE4, 254 ],
       \ [ 0xEE, 0xEE, 0xEE, 255 ]]
 
-    let s:black = 0
-    let s:white = 15
-
     " the 6 values used in the xterm color cube
     "                    0    95   135   175   215   255
     let s:cubergb = [ 0x00, 0x5F, 0x87, 0xAF, 0xD7, 0xFF ]
@@ -187,18 +194,6 @@ if has("gui_running") || &t_Co==256
       endfor
       return best_match
     endfunction
-
-  else
-    " recompile main functions after patching console code for GUI
-    " this avoids having any conditionals on a critical execution path
-    redir => source
-    silent! function s:MatchColorValue
-    redir END
-    let source = substitute( source, '\n[0-9]\+', "\n", 'g' )
-    let source = substitute( source, ' \zsfunction\ze ', 'function!', 'g' )
-    let source = substitute( source, 'cterm\([bf]g\)=', 'gui\1=#', 'g' )
-    let source = substitute( source, 's:XTermColorForRGB(', '(', 'g' )
-    exe source
   endif
 
   hi cssColor000000 guibg=#000000 guifg=#FFFFFF ctermbg=16  ctermfg=231 | syn cluster cssColors add=cssColor000000