From 61d05839a42b56c0759264b493f98d5a516affc4 Mon Sep 17 00:00:00 2001
From: Tom Ryder <tom@sanctum.geek.nz>
Date: Tue, 7 Nov 2017 13:38:10 +1300
Subject: Add user_ftplugin.vim and user_indent.vim plugins

This reverts commit 09b83b6 and replaces it with a working version.

Because of the order in which the autocmd hooks run, the attempted
method of adding unloading instructions for my custom ftplugin and
indent rules to the b:undo_ftplugin and b:undo_indent doesn't actually
work.

This is because the custom rules for both groups from ~/.vim are sourced
*first*, before their core versions, so the changes the custom rules
made to b:undo_ftplugin and b:undo_indent are simply clobbered by the
core version when it loads itself.

Therefore we need to arrange for two things:

1.  A custom variable needs to be checked and executed when the filetype
    changes to revert the changes for the custom ftplugin or indent
    rules.
2.  That execution needs to take place *first* when the filetype
    changes.

I wrote two simple plugins with very similar code that are designed to
run as a user's custom ftplugin.vim and indent.vim implementations,
running before their brethren in the Vim core, and setting up an autocmd
hook to :execute b:undo_user_ftplugin and b:undo_user_indent plugin
respectively.

This seemed to work well, so I've implemented it. It involves adding a
shim to ~/.vim/indent.vim and ~/.vim/ftplugin.vim to "preload" the
plugin when the `filetype indent plugin on` call is made. I've added
that to the relevant Makefile targets.
---
 vim/indent/csv.vim |  9 ++-------
 vim/indent/tsv.vim |  9 ++-------
 vim/indent/vim.vim | 10 +++++-----
 3 files changed, 9 insertions(+), 19 deletions(-)

(limited to 'vim/indent')

diff --git a/vim/indent/csv.vim b/vim/indent/csv.vim
index 24ef53ce..682bc3a8 100644
--- a/vim/indent/csv.vim
+++ b/vim/indent/csv.vim
@@ -1,10 +1,5 @@
 " Manual indenting and literal tabs for CSVs
 setlocal noautoindent
 setlocal noexpandtab
-
-" Undo
-if !exists('b:undo_indent')
-  let b:undo_indent = ''
-endif
-let b:undo_indent = b:undo_indent
-      \ . '|setlocal autoindent< expandtab<'
+let b:undo_user_indent
+      \ = 'setlocal autoindent< expandtab<'
diff --git a/vim/indent/tsv.vim b/vim/indent/tsv.vim
index 161fbbe3..951b3e60 100644
--- a/vim/indent/tsv.vim
+++ b/vim/indent/tsv.vim
@@ -1,10 +1,5 @@
 " Manual indenting and literal tabs for TSVs
 setlocal noautoindent
 setlocal noexpandtab
-
-" Undo
-if !exists('b:undo_indent')
-  let b:undo_indent = ''
-endif
-let b:undo_indent = b:undo_indent
-      \ . '|setlocal autoindent< expandtab<'
+let b:undo_user_indent
+      \ = 'setlocal autoindent< expandtab<'
diff --git a/vim/indent/vim.vim b/vim/indent/vim.vim
index f9a8f211..047a353d 100644
--- a/vim/indent/vim.vim
+++ b/vim/indent/vim.vim
@@ -3,9 +3,9 @@ setlocal shiftwidth=2
 setlocal softtabstop=2
 setlocal tabstop=2
 
-" Undo
-if !exists('b:undo_indent')
-  let b:undo_indent = ''
+" Ancient Vim can't use the '<' suffix syntax for resetting local integer
+" options
+if v:version > 700
+  let b:undo_user_indent
+        \ = 'setlocal shiftwidth< softtabstop< tabstop<'
 endif
-let b:undo_indent = b:undo_indent
-      \ . '|setlocal shiftwidth< softtabstop< tabstop<'
-- 
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