Allow stacking ! operators.

tests/internal_fn.rs

@@ -62,9 +62,9 @@ fn test_internal_fn_overloading() -> Result<(), Box<EvalAltResult>> {
         *engine
             .compile(
                 r"
-                fn abc(x) { x + 42 }
-                fn abc(x) { x - 42 }
-            "
+                    fn abc(x) { x + 42 }
+                    fn abc(x) { x - 42 }
+                "
             )
             .expect_err("should error")
             .0,

tests/not.rs

@@ -12,8 +12,7 @@ fn test_not() -> Result<(), Box<EvalAltResult>> {
     #[cfg(not(feature = "no_function"))]
     assert_eq!(engine.eval::<bool>("fn not(x) { !x } not(false)")?, true);
 
-    // TODO - do we allow stacking unary operators directly? e.g '!!!!!!!true'
-    assert_eq!(engine.eval::<bool>("!(!(!(!(true))))")?, true);
+    assert_eq!(engine.eval::<bool>("!!!!true")?, true);
 
     Ok(())
 }