Code cleanup and refactor.

src/ast/namespace_none.rs

@@ -0,0 +1,22 @@
+//! Namespace reference type.
+#![cfg(feature = "no_module")]
+
+#[cfg(feature = "no_std")]
+use std::prelude::v1::*;
+
+/// _(internals)_ A chain of [module][crate::Module] names to namespace-qualify a variable or function call.
+/// Exported under the `internals` feature only.
+///
+/// Not available under `no_module`.
+#[derive(Debug, Clone, Eq, PartialEq, Default, Hash)]
+pub struct Namespace;
+
+impl Namespace {
+    /// Constant for no namespace.
+    pub const NONE: Self = Self;
+
+    #[inline(always)]
+    pub const fn is_empty(&self) -> bool {
+        true
+    }
+}