add: update config colorscheme

lua/plugins/themes/_globalvar.lua

@@ -0,0 +1,27 @@
+_G.switch = function(param, case_table)
+  local case = case_table[param]
+  if case then
+    return case()
+  end
+  local def = case_table["default"]
+  return def and def() or nil
+end
+
+_G.substring = function(text, key)
+  local index, _ = string.find(text, key)
+  if index then
+    return true
+  else
+    return false
+  end
+end
+
+_G.extract = function(text)
+  local result = {}
+  for substring in string.gmatch(text, "[^_]+") do
+    table.insert(result, substring)
+  end
+  return result
+end
+
+return {}