Move program ast into separate file

src/ast/program.rs

@@ -0,0 +1,17 @@
+use crate::span::{HasSpan, Span};
+
+use super::{Space, TableLitElem};
+
+#[derive(Debug, Clone)]
+pub struct Program {
+    pub elems: Vec<(Space, TableLitElem, Space)>,
+    /// `Some` if there is a trailing comma, `None` otherwise.
+    pub trailing_comma: Option<Space>,
+    pub span: Span,
+}
+
+impl HasSpan for Program {
+    fn span(&self) -> Span {
+        self.span
+    }
+}