convert branch/hunks/bufferline to function names.

autoload/airline/extensions/branch.vim

@@ -31,6 +31,6 @@ function! airline#extensions#branch#get_head()
 endfunction
 
 function! airline#extensions#branch#init(ext)
-  let g:airline_parts.branch = '%{airline#extensions#branch#get_head()}'
+  let g:airline_parts.branch = 'airline#extensions#branch#get_head'
 endfunction
 

autoload/airline/extensions/hunks.vim

@@ -54,6 +54,6 @@ function! airline#extensions#hunks#get_hunks()
 endfunction
 
 function! airline#extensions#hunks#init(ext)
-  let g:airline_parts.hunks = '%{airline#extensions#hunks#get_hunks()}'
+  let g:airline_parts.hunks = 'airline#extensions#hunks#get_hunks'
 endfunction
 

autoload/airline/util.vim

@@ -2,12 +2,15 @@
 " vim: et ts=2 sts=2 sw=2
 
 function! s:get_val(part)
-  let val = g:airline_parts[a:part]
-  if match(val, '%') > -1
-    return val
-  else
-    return '%{function("'.val.'")()}'
+  if has_key(g:airline_parts, a:part)
+    let val = g:airline_parts[a:part]
+    if match(val, '%\| ') > -1
+      return val
+    else
+      return '%{'.val.'()}'
+    endif
   endif
+  return a:part
 endfunction
 
 function! airline#util#define_section(key, parts)

plugin/airline.vim

@@ -81,8 +81,8 @@ function! s:init()
 
     call airline#extensions#load()
     call airline#util#define_section('a', ['mode', 'paste', 'iminsert'])
-    call s:check_defined('g:airline_section_b', (g:airline_parts.hunks).(g:airline_parts.branch))
-    call s:check_defined('g:airline_section_c', '%<'.(g:airline_parts.file))
+    call airline#util#define_section('b', ['hunks', 'branch'])
+    call airline#util#define_section('c', ['%<', 'file'])
     call s:check_defined('g:airline_section_gutter', ' '.(g:airline_parts.readonly).'%=')
     call s:check_defined('g:airline_section_x', (g:airline_parts.tagbar).'%{&filetype}')
     call s:check_defined('g:airline_section_y', g:airline_parts.ffenc)