3 files changed, 59 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/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