Parser: Boolean operations

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionBooleanNode.cs

@@ -13,5 +13,30 @@
         {
             return _value;
         }
+
+        public static bool ConvertToBoolean(object value)
+        {
+            if (value is bool)
+            {
+                return (bool)value;
+            }
+            if (value is decimal)
+            {
+                return (decimal)value == 0;
+            }
+            if (value is string)
+            {
+                string str = (string)value;
+                if (string.IsNullOrEmpty(str) || str == "0" || str.ToLower() == "false")
+                {
+                    return false;
+                }
+                else
+                {
+                    return true;
+                }
+            }
+            return false;
+        }
     }
 }