add gitgutter integration.

autoload/airline/extensions.vim

@@ -128,6 +128,10 @@ function! airline#extensions#load()
     call airline#extensions#undotree#init(s:ext)
   endif
 
+  if g:airline_enable_hunks && exists('*GitGutterGetHunks')
+    call airline#extensions#hunks#init(s:ext)
+  endif
+
   if g:airline_enable_tagbar && exists(':TagbarToggle')
     call airline#extensions#tagbar#init(s:ext)
   endif

autoload/airline/extensions/hunks.vim

@@ -0,0 +1,31 @@
+" MIT License. Copyright (c) 2013 Bailey Ling.
+" vim: et ts=2 sts=2 sw=2
+
+function! airline#extensions#hunks#get_hunks()
+  try
+    " throws an error when first entering a buffer, so we gotta swallow it
+    silent! let hunks = GitGutterGetHunks()
+    let added = 0
+    let removed = 0
+    let changed = 0
+    for hunk in hunks
+      let diff = hunk[3] - hunk[1]
+      if diff > 0
+        let added += diff
+      elseif diff < 0
+        let removed -= diff
+      else
+        let changed += 1
+      endif
+    endfor
+    return printf('+%s ~%s -%s', added, changed, removed)
+  catch
+    return ''
+  endtry
+  return ''
+endfunction
+
+function! airline#extensions#hunks#init(ext)
+  let g:airline_section_b .= '%{airline#extensions#hunks#get_hunks()} '
+endfunction
+