basic support for hiding based on win size per part (#200).

autoload/airline/parts.vim

@@ -22,6 +22,10 @@ function! airline#parts#define_raw(key, raw)
   call airline#parts#define(a:key, { 'raw': a:raw })
 endfunction
 
+function! airline#parts#define_minwidth(key, width)
+  call airline#parts#define(a:key, { 'minwidth': a:width })
+endfunction
+
 function! airline#parts#define_empty(keys)
   for key in a:keys
     call airline#parts#define_raw(key, '')

autoload/airline/section.vim

@@ -19,12 +19,14 @@ function! s:get_val(key, append)
     return a:key
   endif
 
+  let minwidth = get(part, 'minwidth', 0)
+
   if a:append > 0
-    let val .= '%{airline#util#append('.func.')}'
+    let val .= printf('%%{airline#util#append(%s,%s)}', func, minwidth)
   elseif a:append < 0
-    let val .= '%{airline#util#prepend('.func.')}'
+    let val .= printf('%%{airline#util#prepend(%s,%s)}', func, minwidth)
   else
-    let val .= '%{'.func.'}'
+    let val .= printf('%%{airline#util#wrap(%s,%s)}', func, minwidth)
   endif
   return val
 endfunction

autoload/airline/util.vim

@@ -1,11 +1,24 @@
 " MIT License. Copyright (c) 2013 Bailey Ling.
 " vim: et ts=2 sts=2 sw=2
 
-function! airline#util#append(text)
+function! airline#util#wrap(text, minwidth)
+  if a:minwidth > 0 && winwidth(0) < a:minwidth
+    return ''
+  endif
+  return a:text
+endfunction
+
+function! airline#util#append(text, minwidth)
+  if a:minwidth > 0 && winwidth(0) < a:minwidth
+    return ''
+  endif
   return empty(a:text) ? '' : '  '.g:airline_left_alt_sep.' '.a:text
 endfunction
 
-function! airline#util#prepend(text)
+function! airline#util#prepend(text, minwidth)
+  if a:minwidth > 0 && winwidth(0) < a:minwidth
+    return ''
+  endif
   return empty(a:text) ? '' : a:text.' '.g:airline_right_alt_sep.' '
 endfunction