fix logic for selecting brackets to open; same outer level op ranges select incorrectly

inc/expression.hpp

@@ -292,6 +292,43 @@ public:
 	{
 		return (o == SUB || o == DIV);
 	}
+
+	int is_math_op(void) const
+	{
+		if (t != OPERATOR)
+		{
+			return 0;
+		}
+
+		switch (v.o)
+		{
+		case OPA:
+		case CPA:
+			return 0;
+		default:
+			return 1;
+		}
+	}
+
+	int is_opa(void) const
+	{
+		if (t != OPERATOR)
+		{
+			return 0;
+		}
+
+		return v.o == OPA;
+	}
+
+	int is_cpa(void) const
+	{
+		if (t != OPERATOR)
+		{
+			return 0;
+		}
+
+		return v.o == CPA;
+	}
 };
 
 struct Operation