From 51f45f6af445f736ebc2143ed923bd59899e93da Mon Sep 17 00:00:00 2001
From: Tom Ryder <tom@sanctum.geek.nz>
Date: Sat, 25 Apr 2020 17:41:53 +1200
Subject: Roll out the beginnings of XDG support for Vim

The idea here isn't to remove ~/.vim, but to be able to use ~/.cache and
~/.config on a per-machine basis.
---
 Makefile  |  9 +--------
 vim/vimrc | 42 +++++++++++++++++++++++++++++-------------
 2 files changed, 30 insertions(+), 21 deletions(-)

diff --git a/Makefile b/Makefile
index 514a4444..8e537c84 100644
--- a/Makefile
+++ b/Makefile
@@ -588,18 +588,11 @@ install-vim-bundle: install-vim-config
 		'cp -p -- "$$1" $(VIMDIR)/"$${1#*/}"' _ {} \;
 	$(VIM) -e -u NONE -c 'helptags $(VIMDIR)/doc' -c quit
 
-install-vim-cache:
-	mkdir -p -- \
-		$(VIMDIR)/backup \
-		$(VIMDIR)/swap \
-		$(VIMDIR)/undo \
-		$(VIMDIR)/view
-
 install-vim-compiler:
 	mkdir -p -- $(VIMDIR)/compiler
 	cp -p -- vim/compiler/*.vim $(VIMDIR)/compiler
 
-install-vim-config: install-vim-autoload install-vim-cache
+install-vim-config: install-vim-autoload
 	cp -p -- vim/vimrc.stub $(HOME)/.vimrc
 	cp -p -- vim/vimrc $(VIMRC)
 
diff --git a/vim/vimrc b/vim/vimrc
index aed91793..17d1656e 100644
--- a/vim/vimrc
+++ b/vim/vimrc
@@ -104,6 +104,20 @@ elseif &runtimepath !=# ''
   let $MYVIM = option#Split(&runtimepath)[0]
 endif
 
+" TODO: Handle XDG_*_DIRS correctly
+let s:cache = exists('$XDG_CACHE_HOME')
+      \ ? $XDG_CACHE_HOME.'/vim'
+      \ : '~/.cache/vim'
+let s:config = exists('$XDG_CONFIG_HOME')
+      \ ? $XDG_CONFIG_HOME.'/vim'
+      \ : '~/.config/vim'
+let s:data = exists('$XDG_DATA_HOME')
+      \ ? $XDG_DATA_HOME.'/vim'
+      \ : '~/.local/share/vim'
+
+execute 'set runtimepath^='.option#Escape(option#item#Escape(s:config))
+execute 'set runtimepath^='.option#Escape(option#item#Escape(s:cache))
+
 " We need a command to reliably establish a full path, whether or not the
 " directories already exist.  We create a wrapper for the autoloaded function
 " path#Create() with similar calling conventions to mkdir(), but with the ‘p’
@@ -133,8 +147,8 @@ command! -bang -bar -complete=dir -nargs=1 CreatePath
 "
 " <https://github.com/vim/vim/releases/tag/v8.1.0716>
 "
-execute 'set viminfo+='.option#Escape('n'.$MYVIM.'/viminfo')
-call path#Create($MYVIM)
+execute 'set viminfo+='.option#Escape('n'.s:cache.'/viminfo')
+call path#Create(s:cache)
 
 " Speaking of recorded data in viminfo files, the default Vim limit of a mere
 " 50 entries for command and search history is pretty stingy.  Because I don’t
@@ -180,9 +194,9 @@ set history=10000
 "
 set backup
 execute 'set backupdir^='.option#Escape(option#item#Escape(
-      \ $MYVIM.'/backup'.(has#('patch-8.1.251') ? '//' : ''),
+      \ s:cache.'/backup'.(has#('patch-8.1.251') ? '//' : ''),
       \))
-call path#Create($MYVIM.'/backup')
+call path#Create(s:cache.'/backup')
 
 " Files in certain directories on Unix-compatible filesystems should not be
 " backed up, for security reasons.  This is particularly important if editing
@@ -218,9 +232,10 @@ endif
 " option has supported that hint for much longer than 'backupdir' has.  We
 " apply path#Create() to attempt to create the path, if needed.
 "
+let s:swap = s:cache.'/swap'
 execute 'set directory^='
-      \.option#Escape(option#item#Escape($MYVIM.'/swap//'))
-call path#Create($MYVIM.'/swap')
+      \.option#Escape(option#item#Escape(s:swap.'//'))
+call path#Create(s:swap)
 
 " Keep tracked undo history for files permanently, in a dedicated cache
 " directory, so that the u/:undo and CTRL-R/:redo commands will work between
@@ -237,9 +252,10 @@ call path#Create($MYVIM.'/swap')
 "
 if has#('persistent_undo')
   set undofile
+  let s:undodir = s:cache.'/undo'
   execute 'set undodir^='
-        \.option#Escape(option#item#Escape($MYVIM.'/undo//'))
-  call path#Create($MYVIM.'/undo')
+        \.option#Escape(option#item#Escape(s:undodir.'//'))
+  call path#Create(s:undodir)
 endif
 
 " Set up a directory for files generated by :mkview.  To date, I think I have
@@ -248,9 +264,10 @@ endif
 " ('backupdir', 'directory', 'spell', 'undodir')
 "
 if has#('mksession')
+  let s:viewdir = s:cache.'/view'
   execute 'set viewdir='
-        \.option#Escape(option#item#Escape($MYVIM.'/view'))
-  call path#Create($MYVIM.'/view')
+        \.option#Escape(option#item#Escape(s:viewdir))
+  call path#Create(s:viewdir)
 endif
 
 " Now that we have a bit more confidence in our runtime environment, set up
@@ -365,12 +382,11 @@ set spellcapcheck=[.?!]\\%(\ \ \\\|[\\n\\r\\t]\\)
 " around this one with 'isfname'; the blacklist is hard-coded.
 "
 set dictionary^=/usr/share/dict/words
-let s:ref = $MYVIM.'/ref'
 try
   execute 'set dictionary^='
-        \.option#Escape(option#item#Escape(s:ref.'/dictionary.txt'))
+        \.option#Escape(option#item#Escape(s:data.'/dictionary.txt'))
   execute 'set thesaurus^='
-        \.option#Escape(option#item#Escape(s:ref.'/thesaurus.txt'))
+        \.option#Escape(option#item#Escape(s:data.'/thesaurus.txt'))
 catch /^Vim\%((\a\+)\)\=:E474:/
 endtry
 
-- 
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