Merge pull request #5 from opentofu/4_fix_list_and_null_encoding

Fix null/list encoding + example

Author: cam72cam

lib.lua

@@ -5,3 +5,14 @@ end
 function echo(value)
     return value
 end
+
+-- If input array contains single value, return that value, otherwise return the original array.
+function normalize(arr)
+  if type(arr) == "table" and next(arr) == nil then
+    return {}
+  end
+  if type(arr) == "table" and #arr == 0 then
+    return arr[0]
+  end
+  return arr
+end

main.go

@@ -392,12 +392,12 @@ func CtyToLua(arg cty.Value, l *lua.State) error {
 
 func LuaToCty(l *lua.State) (cty.Value, error) {
 	if l.IsNone(-1) {
-		return cty.NilVal, fmt.Errorf("none value should not be returned")
+		return cty.NullVal(cty.DynamicPseudoType), fmt.Errorf("none value should not be returned")
 	}
 
 	switch t := l.TypeOf(-1); t {
 	case lua.TypeNil:
-		return cty.NilVal, nil
+		return cty.NullVal(cty.DynamicPseudoType), nil
 	case lua.TypeBoolean:
 		return cty.BoolVal(l.ToBoolean(-1)), nil
 	case lua.TypeNumber:
@@ -421,7 +421,7 @@ func LuaToCty(l *lua.State) (cty.Value, error) {
 			// Decode key (also modifies)
 			key, ok := l.ToString(-1)
 			if !ok {
-				return cty.NilVal, fmt.Errorf("bad table index")
+				return cty.NullVal(cty.DynamicPseudoType), fmt.Errorf("bad table index")
 			}
 
 			l.Pop(1)
@@ -453,8 +453,8 @@ func LuaToCty(l *lua.State) (cty.Value, error) {
 				return cty.ObjectVal(mv), nil
 			}
 		}
-		return cty.ListVal(av), nil
+		return cty.TupleVal(av), nil
 	default:
-		return cty.NilVal, fmt.Errorf("unhanded return type %s!", t)
+		return cty.NullVal(cty.DynamicPseudoType), fmt.Errorf("unhanded return type %s!", t)
 	}
 }

main.tf

@@ -18,3 +18,15 @@ provider "tester" {
 output "test" {
 	value = provider::tester::echo(tomap({"foo": {"bar": 190}}))
 }
+
+output "norm_0" {
+  value = provider::tester::normalize([])
+}
+
+output "norm_1" {
+  value = provider::tester::normalize([1])
+}
+
+output "norm_2" {
+  value = provider::tester::normalize([1, {"foo": "bar"}])
+}