From a96681d45928fa540107854444e5d755d5f80abc Mon Sep 17 00:00:00 2001
From: Christian Brabandt <cb@256bit.org>
Date: Fri, 11 Aug 2017 11:26:35 +0200
Subject: [PATCH] highlighter: Cache syntax highlighting attributes

Should in theory improve performance by quiet a lot.
---
 autoload/airline/highlighter.vim | 28 +++++++++++++++++++++-------
 plugin/airline.vim               |  1 +
 2 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/autoload/airline/highlighter.vim b/autoload/airline/highlighter.vim
index 4fa3d464..f58ca2af 100644
--- a/autoload/airline/highlighter.vim
+++ b/autoload/airline/highlighter.vim
@@ -10,6 +10,7 @@ let s:is_win32term = (has('win32') || has('win64')) &&
 
 let s:separators = {}
 let s:accents = {}
+let s:hl_groups = {}
 
 function! s:gui2cui(rgb, fallback)
   if a:rgb == ''
@@ -47,14 +48,24 @@ function! s:get_array(fg, bg, opts)
         \ : [ '', '', a:fg, a:bg, opts ]
 endfunction
 
+function! airline#highlighter#reset_hlcache()
+  let s:hl_groups = {}
+endfunction
+
 function! airline#highlighter#get_highlight(group, ...)
-  let fg = s:get_syn(a:group, 'fg')
-  let bg = s:get_syn(a:group, 'bg')
-  let reverse = g:airline_gui_mode ==# 'gui'
-        \ ? synIDattr(synIDtrans(hlID(a:group)), 'reverse', 'gui')
-        \ : synIDattr(synIDtrans(hlID(a:group)), 'reverse', 'cterm')
-        \|| synIDattr(synIDtrans(hlID(a:group)), 'reverse', 'term')
-  return reverse ? s:get_array(bg, fg, a:000) : s:get_array(fg, bg, a:000)
+  if has_key(s:hl_groups, a:group)
+    return s:hl_groups[a:group]
+  else
+    let fg = s:get_syn(a:group, 'fg')
+    let bg = s:get_syn(a:group, 'bg')
+    let reverse = g:airline_gui_mode ==# 'gui'
+          \ ? synIDattr(synIDtrans(hlID(a:group)), 'reverse', 'gui')
+          \ : synIDattr(synIDtrans(hlID(a:group)), 'reverse', 'cterm')
+          \|| synIDattr(synIDtrans(hlID(a:group)), 'reverse', 'term')
+    let res = reverse ? s:get_array(bg, fg, a:000) : s:get_array(fg, bg, a:000)
+  endif
+  let s:hl_groups[a:group] = res
+  return res
 endfunction
 
 function! airline#highlighter#get_highlight2(fg, bg, ...)
@@ -98,6 +109,9 @@ function! airline#highlighter#exec(group, colors)
         \ s:Get(colors, 4, 'gui='), s:Get(colors, 4, 'cterm='),
         \ s:Get(colors, 4, 'term='))
     exe cmd
+    if has_key(s:hl_groups, a:group)
+      let s:hl_groups[a:group] = colors
+    endif
   endif
 endfunction
 
diff --git a/plugin/airline.vim b/plugin/airline.vim
index 84f2048d..51927ded 100644
--- a/plugin/airline.vim
+++ b/plugin/airline.vim
@@ -57,6 +57,7 @@ endfunction
 function! s:on_colorscheme_changed()
   call s:init()
   unlet! g:airline#highlighter#normal_fg_hi
+  call airline#highlighter#reset_hlcache()
   let g:airline_gui_mode = airline#init#gui_mode()
   if !s:theme_in_vimrc
     call airline#switch_matching_theme()