refactor shortening code

autoload/airline/util.vim

@@ -4,6 +4,14 @@
 call airline#init#bootstrap()
 let s:spc = g:airline_symbols.space
 
+function! airline#util#shorten(text, winwidth, minwidth)
+  if winwidth(0) < a:winwidth && len(split(a:text, '\zs')) > a:minwidth
+    return matchstr(a:text, '^.\{'.a:minwidth.'}').'…'
+  else
+    return a:text
+  endif
+endfunction
+
 function! airline#util#wrap(text, minwidth)
   if a:minwidth > 0 && winwidth(0) < a:minwidth
     return ''