From 7352c8ee9e6de8df99efe757602f8e1d37318227 Mon Sep 17 00:00:00 2001
From: Christian Brabandt <cb@256bit.org>
Date: Sat, 6 Feb 2016 17:44:59 +0100
Subject: [PATCH] Detect inconsistent mixed indentation in a file

This is an extension to the whitespace extension.
It can now detect, if there is mixed indentation used within a file,
e.g. (using space for indentation on some lines and using tabs on other
lines.

This fixes #560
---
 autoload/airline/extensions/whitespace.vim | 23 ++++++++++++++++++++--
 doc/airline.txt                            |  7 ++++++-
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/autoload/airline/extensions/whitespace.vim b/autoload/airline/extensions/whitespace.vim
index 9a898c78..0d984d0c 100644
--- a/autoload/airline/extensions/whitespace.vim
+++ b/autoload/airline/extensions/whitespace.vim
@@ -5,11 +5,12 @@
 
 let s:show_message = get(g:, 'airline#extensions#whitespace#show_message', 1)
 let s:symbol = get(g:, 'airline#extensions#whitespace#symbol', g:airline_symbols.whitespace)
-let s:default_checks = ['indent', 'trailing']
+let s:default_checks = ['indent', 'trailing', 'mixed-indent-file']
 
 let s:trailing_format = get(g:, 'airline#extensions#whitespace#trailing_format', 'trailing[%s]')
 let s:mixed_indent_format = get(g:, 'airline#extensions#whitespace#mixed_indent_format', 'mixed-indent[%s]')
 let s:long_format = get(g:, 'airline#extensions#whitespace#long_format', 'long[%s]')
+let s:mixed_indent_file_format = get(g:, 'airline#extensions#whitespace#mixed_indent_file_format', 'mix-indent-file[%s]')
 let s:indent_algo = get(g:, 'airline#extensions#whitespace#mixed_indent_algo', 0)
 
 let s:max_lines = get(g:, 'airline#extensions#whitespace#max_lines', 20000)
@@ -32,6 +33,16 @@ function! s:check_mixed_indent()
   endif
 endfunction
 
+function! s:check_mixed_indent_file()
+  let indent_tabs = search('\v(^\t+)', 'nw')
+  let indent_spc  = search('\v(^ +)', 'nw')
+  if indent_tabs > 0 && indent_spc > 0
+    return printf("%d:%d", indent_tabs, indent_spc)
+  else
+    return ''
+  endif
+endfunction
+
 function! airline#extensions#whitespace#check()
   if &readonly || !&modifiable || !s:enabled || line('$') > s:max_lines
     return ''
@@ -58,12 +69,17 @@ function! airline#extensions#whitespace#check()
       let mixed = s:check_mixed_indent()
     endif
 
+    let mixed_file = ''
+    if index(checks, 'mixed-indent-file') > -1
+      let mixed_file = s:check_mixed_indent_file()
+    endif
+
     let long = 0
     if index(checks, 'long') > -1 && &tw > 0
       let long = search('\%>'.&tw.'v.\+', 'nw')
     endif
 
-    if trailing != 0 || mixed != 0 || long != 0
+    if trailing != 0 || mixed != 0 || long != 0 || !empty(mixed_file)
       let b:airline_whitespace_check = s:symbol
       if s:show_message
         if trailing != 0
@@ -75,6 +91,9 @@ function! airline#extensions#whitespace#check()
         if long != 0
           let b:airline_whitespace_check .= (g:airline_symbols.space).printf(s:long_format, long)
         endif
+        if !empty(mixed_file)
+          let b:airline_whitespace_check .= (g:airline_symbols.space).printf(s:mixed_indent_file_format, mixed_file)
+        endif
       endif
     endif
   endif
diff --git a/doc/airline.txt b/doc/airline.txt
index 787d84a4..c36e76cc 100644
--- a/doc/airline.txt
+++ b/doc/airline.txt
@@ -467,7 +467,11 @@ eclim <https://eclim.org>
   let g:airline#extensions#whitespace#symbol = '!'
 <
 * configure which whitespace checks to enable. >
-  let g:airline#extensions#whitespace#checks = [ 'indent', 'trailing', 'long' ]
+  " indent: mixed indent within a line
+  " long:   overlong lines
+  " trailing: trailing whitespace
+  " mixed-indent-file: different indentation in different lines
+  let g:airline#extensions#whitespace#checks = [ 'indent', 'trailing', 'long', 'mixed-indent-file' ]
 <
 * configure the maximum number of lines where whitespace checking is enabled. >
   let g:airline#extensions#whitespace#max_lines = 20000
@@ -479,6 +483,7 @@ eclim <https://eclim.org>
   let g:airline#extensions#whitespace#trailing_format = 'trailing[%s]'
   let g:airline#extensions#whitespace#mixed_indent_format = 'mixed-indent[%s]'
   let g:airline#extensions#whitespace#long_format = 'long[%s]'
+  let g:airline#extensions#whitespace#mixed_indent_file_format = 'mix-indent-file[%s]'
 
 * configure custom trailing whitespace regexp rule >
   let g:airline#extensions#whitespace#trailing_regexp = '\s$'