Improve compliance/sanity of XDG implementation

2 files changed, 89 insertions, 56 deletions

diff --git a/vim/autoload/xdg.vim b/vim/autoload/xdg.vim
index 675cf460..62d515c1 100644
--- a/vim/autoload/xdg.vim
+++ b/vim/autoload/xdg.vim
@@ -7,6 +7,8 @@ let s:defaults = {
       \ 'XDG_DATA_DIRS': '/usr/local/share/:/usr/share/',
       \}
 
+let s:subdir = 'vim'
+
 function! s:Get(name) abort
   let name = a:name
   let env = environ()
@@ -23,31 +25,38 @@ function! s:Absolute(path) abort
   return a:path =~# '^[/~]'
 endfunction
 
-function! xdg#CacheDir(name) abort
-  let name = a:name
-  let home = s:Get('XDG_CACHE_HOME')
+function! s:Home(name) abort
+  let home = s:Get(a:name)
   if !s:Absolute(home)
     return ''
   endif
-  return join([home, name], '/')
+  return join([home, s:subdir], '/')
 endfunction
 
-function! xdg#ConfigDirs(name) abort
-  let name = a:name
-  let home = s:Get('XDG_CONFIG_HOME')
-  let dirs = split(s:Get('XDG_CONFIG_DIRS'), ':')
-  return map(
-        \ filter(insert(dirs, home), 's:Absolute(v:val)')
-        \,'join([v:val, name], "/")'
-        \)
+function! xdg#CacheHome() abort
+  return s:Home('XDG_CACHE_HOME')
 endfunction
 
-function! xdg#DataDirs(name) abort
-  let name = a:name
-  let home = s:Get('XDG_DATA_HOME')
-  let dirs = split(s:Get('XDG_DATA_DIRS'), ':')
+function! xdg#ConfigHome() abort
+  return s:Home('XDG_CONFIG_HOME')
+endfunction
+
+function! xdg#DataHome() abort
+  return s:Home('XDG_DATA_HOME')
+endfunction
+
+function! s:Dirs(name) abort
+  let dirs = split(s:Get(a:name), ':')
   return map(
-        \ filter(insert(dirs, home), 's:Absolute(v:val)')
-        \,'join([v:val, name], "/")'
+        \ filter(dirs, 's:Absolute(v:val)')
+        \,'join([v:val, s:subdir], "/")'
         \)
 endfunction
+
+function! xdg#ConfigDirs() abort
+  return s:Dirs('XDG_CONFIG_DIRS')
+endfunction
+
+function! xdg#DataDirs() abort
+  return s:Dirs('XDG_DATA_DIRS')
+endfunction
diff --git a/vim/vimrc b/vim/vimrc
index 8afb52d0..b4347b4f 100644
--- a/vim/vimrc
+++ b/vim/vimrc
@@ -103,21 +103,39 @@ endif
 " We'll use the XDG directories as machine-local configuration and storage.
 " <https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html#variables>
 "
+"" Cache
+let s:cache_home = xdg#CacheHome()
+if strlen(s:cache_home) == 0
+  unlet s:cache_home
+endif
 "" Config
-for s:configdir in reverse(xdg#ConfigDirs('vim'))
-  execute 'set runtimepath^='
-        \.option#Escape(option#item#Escape(s:configdir))
-endfor
-"" Cache; put this first so that e.g. spellfiles get created in it
-let s:cachedir = xdg#CacheDir('vim')
-if strlen(s:cachedir)
-  execute 'set runtimepath^='
-        \.option#Escape(option#item#Escape(s:cachedir))
-else
-  unlet s:cachedir
+let s:config_home = xdg#ConfigHome()
+if strlen(s:config_home) == 0
+  unlet s:config_home
 endif
+let s:config_dirs = xdg#ConfigDirs()
 "" Data
-let s:datadir = xdg#DataDirs('vim')[0]
+let s:data_home = xdg#DataHome()
+if strlen(s:data_home) == 0
+  unlet s:data_home
+endif
+let s:data_dirs = xdg#DataDirs()
+
+" Add all the configuration directories to 'runtimepath', and then put the
+" cache home at the very front, so that e.g. 'spellfile' gets created in there
+" rather than in the configuration directories.
+"
+let s:runtime_dirs = s:config_dirs
+if exists('s:config_home')
+  call insert(s:runtime_dirs, s:config_home)
+endif
+if exists('s:cache_home')
+  call insert(s:runtime_dirs, s:config_home)
+endif
+for s:runtime_dir in reverse(s:runtime_dirs)
+  execute 'set runtimepath^='
+        \.option#Escape(option#item#Escape(s:runtime_dir))
+endfor
 
 " 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
@@ -148,9 +166,9 @@ command! -bang -bar -complete=dir -nargs=1 CreatePath
 "
 " <https://github.com/vim/vim/releases/tag/v8.1.0716>
 "
-if exists('s:cachedir')
-  execute 'set viminfo+='.option#Escape('n'.s:cachedir.'/viminfo')
-  call path#Create(s:cachedir)
+if exists('s:cache_home')
+  execute 'set viminfo+='.option#Escape('n'.s:cache_home.'/viminfo')
+  call path#Create(s:cache_home)
 endif
 
 " Speaking of recorded data in viminfo files, the default Vim limit of a mere
@@ -196,11 +214,11 @@ set history=10000
 " 'backupfullname', 'swapfilefullname' would have been clearer.
 "
 set backup
-if exists('s:cachedir')
+if exists('s:cache_home')
   execute 'set backupdir^='.option#Escape(option#item#Escape(
-        \ s:cachedir.'/backup'.(has#('patch-8.1.251') ? '//' : ''),
+        \ s:cache_home.'/backup'.(has#('patch-8.1.251') ? '//' : ''),
         \))
-  call path#Create(s:cachedir.'/backup')
+  call path#Create(s:cache_home.'/backup')
 endif
 
 " Files in certain directories on Unix-compatible filesystems should not be
@@ -237,11 +255,11 @@ endif
 " option has supported that hint for much longer than 'backupdir' has.  We
 " apply path#Create() to attempt to create the path, if needed.
 "
-if exists('s:cachedir')
-  let s:swap = s:cachedir.'/swap'
+if exists('s:cache_home')
+  let s:directory = s:cache_home.'/swap'
   execute 'set directory^='
-        \.option#Escape(option#item#Escape(s:swap.'//'))
-  call path#Create(s:swap)
+        \.option#Escape(option#item#Escape(s:directory.'//'))
+  call path#Create(s:directory)
 endif
 
 " Keep tracked undo history for files permanently, in a dedicated cache
@@ -259,8 +277,8 @@ endif
 "
 if has#('persistent_undo')
   set undofile
-  if exists('s:cachedir')
-    let s:undodir = s:cachedir.'/undo'
+  if exists('s:cache_home')
+    let s:undodir = s:cache_home.'/undo'
     execute 'set undodir^='
           \.option#Escape(option#item#Escape(s:undodir.'//'))
     call path#Create(s:undodir)
@@ -272,8 +290,8 @@ endif
 " directories of this type.  This isn't a comma-separated list like the others
 " ('backupdir', 'directory', 'spell', 'undodir')
 "
-if has#('mksession') && exists('s:cachedir')
-  let s:viewdir = s:cachedir.'/view'
+if has#('mksession') && exists('s:cache_home')
+  let s:viewdir = s:cache_home.'/view'
   execute 'set viewdir='
         \.option#Escape(option#item#Escape(s:viewdir))
   call path#Create(s:viewdir)
@@ -381,21 +399,27 @@ set spellcapcheck=[.?!]\\%(\ \ \\\|[\\n\\r\\t]\\)
 " first two metadata lines from thesaurus.txt, as Vim appeared to interpret
 " them as part of the body data.
 "
-" Extra checks for appending the 'dictionary' and 'thesaurus' paths in MYVIM
-" need to be made, because the P_NDNAME property is assigned to them, which
-" enforces a character blacklist in the option value.  We check for the
-" expected Vim error code here, and if the MYVIM path offends, we just skip
-" the setting entirely, rather than throwing cryptic errors at the user.  None
-" of the blacklisted characters are particularly wise characters to have in
-" paths, anyway, legal though they may be on Unix filesystems.  We can’t work
-" around this one with 'isfname'; the blacklist is hard-coded.
+" Extra checks for appending the 'dictionary' and 'thesaurus' paths need to be
+" made, because the P_NDNAME property is assigned to them, which enforces
+" a character blacklist in the option value.  We check for the expected Vim
+" error code here, and if the path offends, we just skip the setting entirely,
+" rather than throwing cryptic errors at the user.  None of the blacklisted
+" characters are particularly wise characters to have in paths, anyway, legal
+" though they may be on Unix filesystems.  We can’t work around this one with
+" 'isfname'; the blacklist is hard-coded.
 "
 set dictionary^=/usr/share/dict/words
 try
-  execute 'set dictionary^='
-        \.option#Escape(option#item#Escape(s:datadir.'/dictionary.txt'))
-  execute 'set thesaurus^='
-        \.option#Escape(option#item#Escape(s:datadir.'/thesaurus.txt'))
+  let s:ref_dirs = s:data_dirs
+  if exists('s:data_home')
+    call insert(s:ref_dirs, s:data_home)
+  endif
+  for s:ref_dir in reverse(s:ref_dirs)
+    execute 'set dictionary^='
+          \.option#Escape(option#item#Escape(s:ref_dir.'/dictionary.txt'))
+    execute 'set thesaurus^='
+          \.option#Escape(option#item#Escape(s:ref_dir.'/thesaurus.txt'))
+  endfor
 catch /^Vim\%((\a\+)\)\=:E474:/
 endtry