8 files changed, 193 insertions, 4 deletions
diff --git a/runtime/autoload/usermark.vim b/runtime/autoload/usermark.vim
new file mode 100644
index 0000000000..b1b4113d1a
--- /dev/null
+++ b/runtime/autoload/usermark.vim
@@ -0,0 +1,7 @@
+" This is used for the default userreg function.
+
+lua vim.usermark = require('vim.usermark')
+
+function! usermark#func(action, mark) abort
+  return v:lua.vim.usermark.fn(a:action, a:mark)
+endfunction
diff --git a/runtime/autoload/userreg.vim b/runtime/autoload/userreg.vim
new file mode 100644
index 0000000000..fd026a12e6
--- /dev/null
+++ b/runtime/autoload/userreg.vim
@@ -0,0 +1,7 @@
+" This is used for the default userreg function.
+
+lua vim.userreg = require('vim.userreg')
+
+function! userreg#func(action, register, content) abort
+  return v:lua.vim.userreg.fn(a:action, a:register, a:content)
+endfunction
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index b1af90a604..2bd976fa43 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -1371,7 +1371,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 'colorcolumn' 'cc'	string	(default "")
 			local to window
 	'colorcolumn' is a comma-separated list of screen columns that are
-	highlighted with ColorColumn |hl-ColorColumn|.  Useful to align
+	highlighted with ColorColumn |hl-ColorColumn| and drawn using the
+	"colorcol" option from 'fillchars'.  Useful to align
 	text.  Will make screen redrawing slower.
 	The screen column can be an absolute number, or a number preceded with
 	'+' or '-', which is added to or subtracted from 'textwidth'. >
@@ -2501,6 +2502,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 	  diff		'-'		deleted lines of the 'diff' option
 	  msgsep	' '		message separator 'display'
 	  eob		'~'		empty lines at the end of a buffer
+	  colorcol	' '		character to display in the colorcolumn
 	  lastline	'@'		'display' contains lastline/truncate
 
 	Any one that is omitted will fall back to the default.  For "stl" and
@@ -2539,6 +2541,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 	  fold		Folded			|hl-Folded|
 	  diff		DiffDelete		|hl-DiffDelete|
 	  eob		EndOfBuffer		|hl-EndOfBuffer|
+	  colorcol:c	ColorColumn		|hl-ColorColumn|
 	  lastline	NonText			|hl-NonText|
 
 		*'fixendofline'* *'fixeol'* *'nofixendofline'* *'nofixeol'*
@@ -6828,6 +6831,57 @@ A jump table for the options with a short description can be found at |Q_op|.
 	written to disk (see |crash-recovery|).  Also used for the
 	|CursorHold| autocommand event.
 
+						*'userregfunc'* *'urf'*
+'userregfunc' 'urf'	string	(default "")
+			global
+	The option specifies a function to be used to handle any registers
+	that Neovim does not natively handle. This option unlocks all
+	characters to be used as registers by the user.
+
+	The 'userregfunc' function is called each time a user register is read
+	from or written to.
+
+	The 'userregfunc' function must take the following parameters:
+
+		{action} The action being done on this register (either 'yank'
+			or 'put'
+
+		{register} The string holding the name of the register. This
+			is always a single character, though multi-byte
+			characters are allowed.
+
+		{content} If the action is 'yank' this is the content being
+			yanked into the register. The content is a dictionary
+			with the following items:
+
+			{lines} The lines being yanked, as a list.
+
+			{type} The type of yank, either "line", "char", or
+			"block"
+
+			{width} The width in case of "block" mode.
+
+			{additional_data} Additional data. (can be returned in
+			put mode).
+
+	In case the action is 'put', the 'userregfunc' function should return
+	the content to place in that location. The content can either be a
+	string, in which case "char" mode is inferred, or it can return a
+	dictionary of the same template that populates 'content'.
+
+	A very simple example of a 'userregfunc' function that behaves exactly
+	like traditional registers would look like: >
+		
+		let s:contents = {}
+		function! MyUserregFunction(action, register, content) abort
+		   if a:action == "put"
+		     return get(s:contents, a:register, "")
+		  else
+		     let s:contents[a:register] = a:content
+		  endif
+		endfunction
+		set userregfunc=MyUserregFunction
+<
 					*'varsofttabstop'* *'vsts'*
 'varsofttabstop' 'vsts'	string	(default "")
 			local to buffer
diff --git a/runtime/lua/vim/lsp/semantic_tokens.lua b/runtime/lua/vim/lsp/semantic_tokens.lua
index b1bc48dac6..a9d3d0cbd6 100644
--- a/runtime/lua/vim/lsp/semantic_tokens.lua
+++ b/runtime/lua/vim/lsp/semantic_tokens.lua
@@ -330,7 +330,7 @@ function STHighlighter:process_response(response, client, version)
     end
     vim.list_extend(tokens, old_tokens, idx)
   else
-    tokens = response.data
+    tokens = response.data or {}
   end
 
   -- Update the state with the new results
@@ -378,7 +378,7 @@ function STHighlighter:on_win(topline, botline)
       --
       -- Instead, we have to use normal extmarks that can attach to locations
       -- in the buffer and are persisted between redraws.
-      local highlights = current_result.highlights
+      local highlights = current_result.highlights or {}
       local idx = binary_search(highlights, topline)
 
       for i = idx, #highlights do
@@ -612,7 +612,7 @@ function M.get_at_pos(bufnr, row, col)
 
   local tokens = {}
   for client_id, client in pairs(highlighter.client_state) do
-    local highlights = client.current_result.highlights
+    local highlights = client.current_result.highlights or {}
     if highlights then
       local idx = binary_search(highlights, row)
       for i = idx, #highlights do
diff --git a/runtime/lua/vim/usermark.lua b/runtime/lua/vim/usermark.lua
new file mode 100644
index 0000000000..0d1ec0ae0f
--- /dev/null
+++ b/runtime/lua/vim/usermark.lua
@@ -0,0 +1,68 @@
+-- Defualt implementation of the usermarkfunc. This default implementation is
+-- extensible and allows other plugins to register handlers for different
+-- registers.
+--
+-- The default handler behaves just as a normal register would.
+
+local vim = assert(vim)
+local usermark = {}
+
+-- Returns a "default handler" which behaves like normal global marks. When a
+-- call to set() is made, it stores the current line and col of the cursor and
+-- the filename of the current file.
+function usermark._default_handler()
+  local d = {}
+
+  -- Called when a mark is recalled using the "'" command. Just returns what was
+  -- stored before or nothing if it was never set before.
+  function d.get(self, mark)
+    return self.content or {}
+  end
+
+  -- Called when a mark is set using the "m" command. Stores the current cursor
+  -- position to be recalled at a later time.
+  function d.set(self, mark)
+    local r,c = unpack(vim.api.nvim_win_get_cursor(0))
+    local file = vim.fn.expand("%:p")
+
+    self.content = {
+      line = r;
+      col = c;
+    }
+
+    if file ~= '' then
+      self.content.file = file
+    end
+  end
+
+  return d
+end
+
+-- The store for register default handler
+usermark._marktable = {}
+
+-- Function for the 'usermarkfunc'. Will defer to the handler associated with
+-- the provided mark.
+--
+-- If not handler is registered to a given mark, the default handler is used,
+-- which is a re-implementation of standard mark behavior.
+function usermark.fn(action, mark)
+  if not usermark._marktable[mark] then
+    usermark._marktable[mark] = usermark._default_handler()
+  end
+
+  if action == "get" then
+    return usermark._marktable[mark]:get(mark)
+  else 
+    usermark._marktable[mark]:set(mark)
+    return nil
+  end
+end
+
+-- Registers a handler with a mark. Gets and sets will then defer to this
+-- handler when determining the mark's behavior.
+function usermark.register_handler(mark, handler) 
+  usermark._marktable[mark] = handler
+end
+
+return usermark
diff --git a/runtime/lua/vim/userreg.lua b/runtime/lua/vim/userreg.lua
new file mode 100644
index 0000000000..5abcff0407
--- /dev/null
+++ b/runtime/lua/vim/userreg.lua
@@ -0,0 +1,51 @@
+-- Defualt implementation of the userregfunc. This default implementation is
+-- extensible and allows other plugins to register handlers for different
+-- registers.
+--
+-- The default handler behaves just as a normal register would.
+
+local userreg = {}
+
+-- Returns a "default handler" which behaves exactly like the builtin registers
+-- in Vim. Simply stores whatever was yanked and returns the last thing that was
+-- yanked.
+function userreg._default_handler()
+  local d = {}
+
+  function d.do_yank(self, content)
+    self.content = content
+  end
+
+  function d.do_put(self)
+    return self.content or {}
+  end
+
+  return d
+end
+
+-- The store for registers default handler
+userreg._regtable = {}
+
+-- Function for the userreg. This function will defer to the handler registered
+-- to the given register. If no handler is registered to the given register, the
+-- default handler is used.
+function userreg.fn(action, register, content)
+  if not userreg._regtable[register] then
+    userreg._regtable[register] = userreg._default_handler()
+  end
+
+  if action == "yank" then
+    userreg._regtable[register]:do_yank(content)
+    return nil
+  else 
+    return userreg._regtable[register]:do_put()
+  end
+end
+
+-- Registers a handler with a register. Future yanks and puts will defer to the
+-- handler when determining the content to put/yank.
+function userreg.register_handler(register, handler) 
+  userreg._regtable[register] = handler
+end
+
+return userreg
diff --git a/runtime/plugin/usermark.vim b/runtime/plugin/usermark.vim
new file mode 100644
index 0000000000..917e7510f1
--- /dev/null
+++ b/runtime/plugin/usermark.vim
@@ -0,0 +1 @@
+set usermarkfunc=usermark#func
diff --git a/runtime/plugin/userreg.vim b/runtime/plugin/userreg.vim
new file mode 100644
index 0000000000..099e7c65cb
--- /dev/null
+++ b/runtime/plugin/userreg.vim
@@ -0,0 +1 @@
+set userregfunc=userreg#func