Use SmartString in parsing.

src/ast/script_fn.rs

@@ -1,12 +1,21 @@
 //! Module defining script-defined functions.
 #![cfg(not(feature = "no_function"))]
 
-use super::{FnAccess, StmtBlock};
+use super::StmtBlock;
 use crate::{Identifier, StaticVec};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
 use std::{fmt, hash::Hash};
 
+/// A type representing the access mode of a function.
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash)]
+pub enum FnAccess {
+    /// Private function.
+    Private,
+    /// Public function.
+    Public,
+}
+
 /// _(internals)_ Encapsulated AST environment.
 /// Exported under the `internals` feature only.
 ///