From 9c960875fe5433f26bfe67ee789a1e67aee147ee Mon Sep 17 00:00:00 2001
From: Bailey Ling <bling@live.ca>
Date: Tue, 6 Aug 2013 03:07:01 +0000
Subject: [PATCH] extract fugitive/lawrencium

---
 autoload/airline/extensions.vim        | 11 ++++-------
 autoload/airline/extensions/branch.vim | 16 ++++++++++++++++
 plugin/airline.vim                     |  2 +-
 3 files changed, 21 insertions(+), 8 deletions(-)
 create mode 100644 autoload/airline/extensions/branch.vim

diff --git a/autoload/airline/extensions.vim b/autoload/airline/extensions.vim
index d2534cb..891007d 100644
--- a/autoload/airline/extensions.vim
+++ b/autoload/airline/extensions.vim
@@ -19,13 +19,6 @@ function! airline#extensions#apply_left_override(section1, section2)
 endfunction
 
 function! airline#extensions#update_external_values()
-  let g:airline_externals_branch = g:airline_enable_branch
-        \ ? (exists('*fugitive#head') && strlen(fugitive#head()) > 0
-          \ ? g:airline_branch_prefix.fugitive#head()
-          \ : exists('*lawrencium#statusline') && strlen(lawrencium#statusline()) > 0
-            \ ? g:airline_branch_prefix.lawrencium#statusline()
-            \ : '')
-        \ : ''
   let g:airline_externals_tagbar = g:airline_enable_tagbar && exists(':Tagbar')
         \ ? '%(%{tagbar#currenttag("%s","")} '.g:airline_right_alt_sep.' %)' : ''
 endfunction
@@ -121,6 +114,10 @@ function! airline#extensions#load()
     call airline#extensions#commandt#init(s:ext)
   endif
 
+  if g:airline_enable_branch && (get(g:, 'loaded_fugitive', 0) || get(g:, 'loaded_lawrencium', 0))
+    call airline#extensions#branch#init(s:ext)
+  endif
+
   if g:airline_enable_syntastic && get(g:, 'loaded_syntastic_plugin')
     call airline#extensions#syntastic#init(s:ext)
   endif
diff --git a/autoload/airline/extensions/branch.vim b/autoload/airline/extensions/branch.vim
new file mode 100644
index 0000000..08a0687
--- /dev/null
+++ b/autoload/airline/extensions/branch.vim
@@ -0,0 +1,16 @@
+" MIT license. Copyright (c) 2013 Bailey Ling.
+" vim: ts=2 sts=2 sw=2 fdm=indent
+
+function! airline#extensions#branch#apply()
+  let w:airline_section_b =
+        \ exists('*fugitive#head') && strlen(fugitive#head()) > 0
+          \ ? g:airline_branch_prefix.fugitive#head()
+          \ : exists('*lawrencium#statusline') && strlen(lawrencium#statusline()) > 0
+            \ ? g:airline_branch_prefix.lawrencium#statusline()
+            \ : ''
+endfunction
+
+function! airline#extensions#branch#init(ext)
+  call a:ext.add_statusline_funcref(function('airline#extensions#branch#apply'))
+endfunction
+
diff --git a/plugin/airline.vim b/plugin/airline.vim
index 537b2b1..745f214 100644
--- a/plugin/airline.vim
+++ b/plugin/airline.vim
@@ -56,7 +56,7 @@ function! s:on_window_changed()
     call airline#extensions#load()
     call airline#load_theme(g:airline_theme)
     call s:check_defined('g:airline_section_a', '%{g:airline_current_mode_text}')
-    call s:check_defined('g:airline_section_b', '%{g:airline_externals_branch}')
+    call s:check_defined('g:airline_section_b', '')
     call s:check_defined('g:airline_section_c', '%f%m')
     call s:check_defined('g:airline_section_gutter', '')
     call s:check_defined('g:airline_section_x', g:airline_externals_tagbar."%{strlen(&filetype)>0?&filetype:''}")