From 583121bbc9ed8b1142c14a938bca4a652c4dcfa9 Mon Sep 17 00:00:00 2001
From: Christian Brabandt <cb@256bit.org>
Date: Mon, 20 Feb 2017 20:24:43 +0100
Subject: [PATCH 1/3] before trying to return hi attributes, check the group
 exists

This prevents trying to access twice the highlighting groups
and should slightly speed up airline.
---
 autoload/airline/highlighter.vim | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/autoload/airline/highlighter.vim b/autoload/airline/highlighter.vim
index 5cbf590..a38d93a 100644
--- a/autoload/airline/highlighter.vim
+++ b/autoload/airline/highlighter.vim
@@ -22,12 +22,17 @@ function! s:get_syn(group, what)
   if !exists("g:airline_gui_mode")
     let g:airline_gui_mode = airline#init#gui_mode()
   endif
-  let color = synIDattr(synIDtrans(hlID(a:group)), a:what, g:airline_gui_mode)
-  if empty(color) || color == -1
-    let color = synIDattr(synIDtrans(hlID('Normal')), a:what, g:airline_gui_mode)
+  let color = ''
+  if hlexists(a:group)
+    let color = synIDattr(synIDtrans(hlID(a:group)), a:what, g:airline_gui_mode)
   endif
   if empty(color) || color == -1
-    let color = 'NONE'
+    " should always exists
+    let color = synIDattr(synIDtrans(hlID('Normal')), a:what, g:airline_gui_mode)
+    " however, just in case
+    if empty(color) || color == -1
+      let color = 'NONE'
+    endif
   endif
   return color
 endfunction

From 69b132a6f4349732ad8c147f736822d54d09f071 Mon Sep 17 00:00:00 2001
From: Christian Brabandt <cb@256bit.org>
Date: Mon, 20 Feb 2017 21:02:36 +0100
Subject: [PATCH 2/3] Make sure, the highlighting group will be defined

If a color value of ['', '', 'NONE', 'NONE', ''] is given as value to
the highlighting group, the resulting group definition would look like
this:

hi Normal ctermfg=NONE ctermbg=NONE

which would result in the highlighting group being cleared (or even no
set at all), therefore check that at least one other value exists and if
not fall back to the highlighting definition of the Normal group.
---
 autoload/airline/highlighter.vim | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/autoload/airline/highlighter.vim b/autoload/airline/highlighter.vim
index a38d93a..6af3207 100644
--- a/autoload/airline/highlighter.vim
+++ b/autoload/airline/highlighter.vim
@@ -72,6 +72,7 @@ function! airline#highlighter#exec(group, colors)
   if len(colors) == 4
     call add(colors, '')
   endif
+  let colors = s:CheckDefined(colors)
   if old_hi != colors
     let cmd = printf('hi %s %s %s %s %s %s %s %s',
         \ a:group, s:Get(colors, 0, 'guifg=', ''), s:Get(colors, 1, 'guibg=', ''),
@@ -82,6 +83,24 @@ function! airline#highlighter#exec(group, colors)
   endif
 endfunction
 
+function! s:CheckDefined(colors)
+  " Checks, whether the definition of the colors is valid and is not empty or NONE
+  " e.g. if the colors would expand to this:
+  " hi airline_c ctermfg=NONE ctermbg=NONE
+  " that means to clear that highlighting group, therefore, add a special term=NONE
+  " argument
+  for val in a:colors
+    if !empty(val) && val !=# 'NONE'
+      return a:colors
+    endif
+  endfor
+  " this adds the bold attribute to the term argument of the :hi command,
+  " but at least this makes sure, the group will be defined
+  let fg = synIDattr(synIDtrans(hlID('Normal')), 'fg', 'cterm')
+  let bg = synIDattr(synIDtrans(hlID('Normal')), 'bg', 'cterm')
+  return a:colors[0:1] + [fg, bg] + [a:colors[4]]
+endfunction
+
 function! s:Get(dict, key, prefix, default)
   if get(a:dict, a:key, a:default) isnot# a:default
     return a:prefix. get(a:dict, a:key)

From f1574c4e0aeb56bcbefe2e38892c6e97e3fd612c Mon Sep 17 00:00:00 2001
From: Christian Brabandt <cb@256bit.org>
Date: Mon, 20 Feb 2017 21:08:38 +0100
Subject: [PATCH 3/3] define highlighting group, if it not exists

previously, it could have been skipped, if the old highlighting
attribute was the same as the current one. However, if the group does
not exist, it should still be defined

closes #1404
---
 autoload/airline/highlighter.vim | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/autoload/airline/highlighter.vim b/autoload/airline/highlighter.vim
index 6af3207..e4e83e8 100644
--- a/autoload/airline/highlighter.vim
+++ b/autoload/airline/highlighter.vim
@@ -73,7 +73,7 @@ function! airline#highlighter#exec(group, colors)
     call add(colors, '')
   endif
   let colors = s:CheckDefined(colors)
-  if old_hi != colors
+  if old_hi != colors || !hlexists(a:group)
     let cmd = printf('hi %s %s %s %s %s %s %s %s',
         \ a:group, s:Get(colors, 0, 'guifg=', ''), s:Get(colors, 1, 'guibg=', ''),
         \ s:Get(colors, 2, 'ctermfg=', ''), s:Get(colors, 3, 'ctermbg=', ''),