Add vim-xkblayout extension to display keyboard layout

autoload/airline/extensions.vim

@@ -284,6 +284,11 @@ function! airline#extensions#load()
     call add(loaded_ext, 'capslock')
   endif
 
+  if (get(g:, 'airline#extensions#xkblayout#enabled', 1) && exists('g:XkbSwitchLib'))
+    call airline#extensions#xkblayout#init(s:ext)
+    call add(loaded_ext, 'xkblayout')
+  endif
+
   if (get(g:, 'airline#extensions#windowswap#enabled', 1) && get(g:, 'loaded_windowswap', 0))
     call airline#extensions#windowswap#init(s:ext)
     call add(loaded_ext, 'windowswap')

autoload/airline/extensions/xkblayout.vim

@@ -0,0 +1,25 @@
+" MIT License. Copyright (c) 2017 YoungHoon Rhiu.
+" vim: et ts=2 sts=2 sw=2
+
+scriptencoding utf-8
+
+if !exists('g:XkbSwitchLib')
+  finish
+endif
+
+function! airline#extensions#xkblayout#status()
+  let keyboard_layout = libcall(g:XkbSwitchLib, 'Xkb_Switch_getXkbLayout', '')
+  let keyboard_layout = split(keyboard_layout, '\.')[-1]
+  let short_codes = {'2SetKorean': 'KR', 'Chinese': 'CN', 'Japanese': 'JP'}
+
+  if has_key(short_codes, keyboard_layout)
+    let keyboard_layout = short_codes[keyboard_layout]
+  endif
+
+  return keyboard_layout
+endfunction
+
+function! airline#extensions#xkblayout#init(ext)
+  call airline#parts#define_function('xkblayout', 'airline#extensions#xkblayout#status')
+endfunction
+

autoload/airline/init.vim

@@ -104,6 +104,7 @@ function! airline#init#bootstrap()
         \ 'eclim', 'whitespace','windowswap', 'ycm_error_count', 'ycm_warning_count',
         \ 'neomake_error_count', 'neomake_warning_count', 'ale_error_count', 'ale_warning_count'])
   call airline#parts#define_text('capslock', '')
+  call airline#parts#define_text('xkblayout', '')
 
   unlet g:airline#init#bootstrapping
 endfunction
@@ -117,7 +118,7 @@ endfunction
 function! airline#init#sections()
   let spc = g:airline_symbols.space
   if !exists('g:airline_section_a')
-    let g:airline_section_a = airline#section#create_left(['mode', 'crypt', 'paste', 'spell', 'capslock', 'iminsert'])
+    let g:airline_section_a = airline#section#create_left(['mode', 'crypt', 'paste', 'spell', 'capslock', 'xkblayout', 'iminsert'])
   endif
   if !exists('g:airline_section_b')
     let g:airline_section_b = airline#section#create(['hunks', 'branch'])

doc/airline.txt

@@ -754,6 +754,18 @@ vim-capslock <https://github.com/tpope/vim-capslock>
 * enable/disable vim-capslock integration >
   let g:airline#extensions#capslock#enabled = 1
 
+-------------------------------------                     *airline-xkblayout*
+vim-xkblayout
+
+* enable/disable vim-xkblayout extension >
+  let g:airline#extensions#xkblayout#enabled = 1
+
+* define path to the backend switcher library
+  Linux (Install https://github.com/ierton/xkb-switch):
+   let g:XkbSwitchLib = '/usr/local/lib/libxkbswitch.so'
+  macOS (Install https://github.com/vovkasm/input-source-switcher):
+   let g:XkbSwitchLib = '/usr/local/lib/libInputSourceSwitcher.dylib'
+
 -------------------------------------                   *airline-windowswap*
 vim-windowswap <https://github.com/wesQ3/vim-windowswap>