implement almost full customization support. resolves #3

autoload/airline/themes/default.vim

@@ -11,7 +11,7 @@ let g:airline#themes#default#normal = {
       \ 'inactive':       [ '#4e4e4e' , '#1c1c1c' , 239     , 234     , ''     ] ,
       \ }
 let g:airline#themes#default#normal_modified = copy(g:airline#themes#default#normal)
-let g:airline#themes#default#normal_modified.info_separator = [ '#444444' , '#5f005f' , s:N2[3] , 53 , '' ]
+let g:airline#themes#default#normal_modified.info_separator = [ '#444444' , '#5f005f' , 238 , 53 , '' ]
 let g:airline#themes#default#normal_modified.statusline     = [ '#ffffff' , '#5f005f' , 255 , 53 , '' ]
 
 let s:I1 = [ '#00005f' , '#00dfff' , 17  , 45  ]

doc/airline.txt

@@ -65,6 +65,11 @@ values):
   let g:airline_powerline_fonts=0
 <
 
+* define the set of text to display for each mode.
+>
+  let g:airline_mode_map = {} " see source for current list
+<
+
 * define the set of filename match queries which excludes a window from having
   its statusline modified
 >
@@ -98,11 +103,23 @@ well as the powerline font glyths
   let g:airline_left_sep = ''
   let g:airline_right_sep = ''
   let g:airline_right_sep = ''
-  let g:airline_fugitive_prefix = '   '
+  let g:airline_fugitive_prefix = ' '
   let g:airline_readonly_symbol = ''
   let g:airline_linecolumn_prefix = ' '
 <
 
+for more intricate customizations, you can replace the predefined sections
+with the usual *statusline* syntax.
+
+>
+  let g:airline_section_a (the mode indicator)
+  let g:airline_section_b (the fugitive branch indicator)
+  let g:airline_section_c (bufferline or filename)
+  let g:airline_section_x (filetype)
+  let g:airline_section_y (fileencoding, fileformat)
+  let g:airline_section_z (percentage, line number, column number)
+<
+
 ==============================================================================
 CONTRIBUTIONS                                        *airline-contributions*
 

plugin/airline.vim

@@ -1,4 +1,4 @@
-" vim: ts=2 sts=2 sw=2
+" vim: ts=2 sts=2 sw=2 fdm=indent
 if &cp || v:version < 702 || (exists('g:loaded_airline') && g:loaded_airline)
   finish
 endif
@@ -16,7 +16,7 @@ call s:check_defined('g:airline_right_sep', exists('g:airline_powerline_fonts')?
 call s:check_defined('g:airline_enable_bufferline', 1)
 call s:check_defined('g:airline_enable_fugitive', 1)
 call s:check_defined('g:airline_enable_syntastic', 1)
-call s:check_defined('g:airline_fugitive_prefix', exists('g:airline_powerline_fonts')?'   ':' ')
+call s:check_defined('g:airline_fugitive_prefix', exists('g:airline_powerline_fonts')?' ':'')
 call s:check_defined('g:airline_readonly_symbol', exists('g:airline_powerline_fonts')?'':'RO')
 call s:check_defined('g:airline_linecolumn_prefix', exists('g:airline_powerline_fonts')?' ':':')
 call s:check_defined('g:airline_theme', 'default')
@@ -27,15 +27,15 @@ call s:check_defined('g:airline_exclude_filetypes', ['qf','netrw','diff','undotr
 let s:is_win32term = (has('win32') || has('win64')) && !has('gui_running')
 let s:load_the_theme = g:airline#themes#{g:airline_theme}#normal
 
-let s:airline_mode_map = {
+call s:check_defined('g:airline_mode_map', {
-      \ 'n'  : '  NORMAL ',
+      \ 'n'  : 'NORMAL',
-      \ 'i'  : '  INSERT ',
+      \ 'i'  : 'INSERT',
-      \ 'R'  : '  RPLACE ',
+      \ 'R'  : 'RPLACE',
-      \ 'v'  : '  VISUAL ',
+      \ 'v'  : 'VISUAL',
-      \ 'V'  : '  V-LINE ',
+      \ 'V'  : 'V-LINE',
-      \ 'c'  : '  CMD    ',
+      \ 'c'  : 'CMD   ',
-      \ '' : '  V-BLCK ',
+      \ '' : 'V-BLCK',
-      \ }
+      \ })
 let s:airline_highlight_map = {
       \ 'mode'           : 'User2',
       \ 'mode_separator' : 'User3',
@@ -82,10 +82,19 @@ function! s:is_excluded_window()
 endfunction
 
 function! s:update_externals()
-  let g:airline_externals_bufferline = g:airline_enable_bufferline && exists('g:bufferline_loaded') ? bufferline#generate_string() : "%f%m"
+  let g:airline_externals_bufferline = g:airline_enable_bufferline && exists('g:bufferline_loaded') ? '%{bufferline#generate_string()}' : "%f%m"
-  let g:airline_externals_fugitive = g:airline_enable_fugitive && exists('g:loaded_fugitive') ? g:airline_fugitive_prefix.fugitive#head() : ''
   let g:airline_externals_syntastic = g:airline_enable_syntastic && exists('g:loaded_syntastic_plugin') ? '%{SyntasticStatuslineFlag()}' : ''
+  let g:airline_externals_fugitive = g:airline_enable_fugitive && exists('g:loaded_fugitive') && strlen(fugitive#head()) > 0
+        \ ? g:airline_fugitive_prefix.fugitive#head() : ''
 endfunction
+call s:update_externals()
+
+call s:check_defined('g:airline_section_a', '%{g:airline_current_mode_text}')
+call s:check_defined('g:airline_section_b', '%{g:airline_externals_fugitive}')
+call s:check_defined('g:airline_section_c', g:airline_externals_bufferline)
+call s:check_defined('g:airline_section_x', "%{strlen(&filetype)>0?&filetype:''}")
+call s:check_defined('g:airline_section_y', "%{strlen(&fenc)>0?&fenc:''}%{strlen(&ff)>0?'['.&ff.']':''}")
+call s:check_defined('g:airline_section_z', '%3p%% '.g:airline_linecolumn_prefix.'%3l:%3c')
 
 function! s:update_statusline(active)
   if s:is_excluded_window()
@@ -100,30 +109,34 @@ function! s:update_statusline(active)
   let l:status_color = a:active ? "%6*" : "%9*"
   let l:file_flag_color = a:active ? "%8*" : "%9*"
 
-  let sl = a:active ? l:mode_color."%{AirlineModePrefix()}".l:mode_sep_color : l:mode_color." NORMAL %9*"
+  let sl = l:mode_color
-  let sl.="%{g:airline_left_sep}".l:info_color
+  let sl.= a:active
-  let sl.=g:airline_externals_fugitive
+        \ ? '%{AirlineUpdateHighlight()} '.g:airline_section_a.' '.l:mode_sep_color
-  let sl.=' '.l:info_sep_color."%{g:airline_left_sep}"
+        \ : '        %9*'
+  let sl.='%{g:airline_left_sep}'.l:info_color
+  let sl.=' '.g:airline_section_b.' '
+  let sl.=l:info_sep_color.g:airline_left_sep
   if a:active
-    let sl.=l:status_color.' '.g:airline_externals_bufferline.' '
+    let sl.=l:status_color.' '.g:airline_section_c.' '
   else
     let sl.=" ".bufname(winbufnr(winnr()))
   endif
   let sl.="%#warningmsg#"
   let sl.=g:airline_externals_syntastic
-  let sl.=l:status_color."%<%=".l:file_flag_color."%{&ro? g:airline_readonly_symbol :''}"
+  let sl.=l:status_color."%<%=".l:file_flag_color."%{&ro ? g:airline_readonly_symbol : ''}"
   let sl.="%q%{&previewwindow?'[preview]':''}"
-  let sl.=l:status_color."\ %{strlen(&filetype)>0?&filetype:''}\ "
+  let sl.=l:status_color
-  let sl.=l:info_sep_color."%{g:airline_right_sep}".l:info_color."\ "
+  let sl.=' '.g:airline_section_x.' '
-  let sl.="%{strlen(&fileencoding)>0?&fileencoding:''}"
+  let sl.=l:info_sep_color.g:airline_right_sep.l:info_color
-  let sl.="%{strlen(&fileformat)>0?'['.&fileformat.']':''}"
+  let sl.=' '.g:airline_section_y.' '
-  let sl.="\ ".l:mode_sep_color."%{g:airline_right_sep}"
+  let sl.=l:mode_sep_color.g:airline_right_sep.l:mode_color
-  let sl.=l:mode_color."\ %3p%%\ ".g:airline_linecolumn_prefix."%3l:%3c\ "
+  let sl.=' '.g:airline_section_z.' '
   call setwinvar(winnr(), '&statusline', sl)
 endfunction
 
 let s:lastmode = ''
-function! AirlineModePrefix()
+let g:airline_current_mode_text = ''
+function! AirlineUpdateHighlight()
   let l:m = mode()
   let l:mode = 'normal'
   if l:m ==# "i" || l:m ==# "R"
@@ -141,10 +154,8 @@ function! AirlineModePrefix()
     let s:lastmode = l:mode
   endif
 
-  if has_key(s:airline_mode_map, l:m)
+  let g:airline_current_mode_text = get(g:airline_mode_map, l:m, l:m)
-    return s:airline_mode_map[l:m]
+  return ''
-  endif
-  return l:mode
 endfunction
 
 augroup airline