Added stackable function `optional()`. ref https://github.com/sailorproject/valua/issues/10

1 files changed, 12 insertions, 2 deletions

diff --git a/valua.lua b/valua.lua
index 6e1c6e4..11d4741 100644
--- a/valua.lua
+++ b/valua.lua
@@ -41,8 +41,12 @@ function valua:new(obj)
 		--saves a function named _<index> with its args in a funcs table, to be used later when validating
 		return function(...)
 			local args = pack(...)
-			local f = function(value) return valua['_'..k](value, unpack(args, 1, args.n)) end
-			tinsert(t.funcs,f)
+      if k == 'optional' then
+        obj.allow_nil = true
+      else
+        local f = function(value) return valua['_'..k](value, unpack(args, 1, args.n)) end
+        tinsert(t.funcs,f)
+      end
 			return t
 		end
 	end
@@ -51,6 +55,11 @@ function valua:new(obj)
 	self.__call = function(t,value)
 		local res = true
 		local fres, err
+
+    if value == nil and t.allow_nil then
+      return res, err
+    end
+
 		-- iterates through all chained validations funcs that were packed, passing the value to be validated
 		for _,f in ipairs(t.funcs) do
 			fres,err = f(value)
@@ -64,6 +73,7 @@ function valua:new(obj)
 		return res,err
 	end
 	obj.funcs = {}
+  obj.allow_nil = false
 	return obj
 end
 --