4 files changed, 110 insertions, 0 deletions
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 4d186bd761..b35049343d 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -6757,6 +6757,57 @@ 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/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/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