diff --git a/src/protocol/ast.rs b/src/protocol/ast.rs
index 1a8b15815835a0aa5b320791193ad9cfa98942d1..ca6efe6af2637d61f1d1d50fa3cd87285916d4d0 100644
--- a/src/protocol/ast.rs
+++ b/src/protocol/ast.rs
@@ -340,6 +340,15 @@ pub struct Identifier {
     pub value: StringRef<'static>,
 }
 
+impl Identifier {
+    pub(crate) fn new_empty(span: InputSpan) -> Identifier {
+        return Identifier{
+            span,
+            value: StringRef::new_empty(),
+        };
+    }
+}
+
 impl PartialEq for Identifier {
     fn eq(&self, other: &Self) -> bool {
         return self.value == other.value
@@ -1432,7 +1441,7 @@ pub enum ExpressionParent {
     Return(ReturnStatementId),
     New(NewStatementId),
     ExpressionStmt(ExpressionStatementId),
-    Expression(ExpressionId, u32) // index within expression (e.g LHS or RHS of expression)
+    Expression(ExpressionId, u32) // index within expression (e.g LHS or RHS of expression, or index in array literal, etc.)
 }
 
 impl ExpressionParent {
@@ -1530,6 +1539,23 @@ impl Expression {
         }
     }
 
+    pub fn parent_mut(&mut self) -> &mut ExpressionParent {
+        match self {
+            Expression::Assignment(expr) => &mut expr.parent,
+            Expression::Binding(expr) => &mut expr.parent,
+            Expression::Conditional(expr) => &mut expr.parent,
+            Expression::Binary(expr) => &mut expr.parent,
+            Expression::Unary(expr) => &mut expr.parent,
+            Expression::Indexing(expr) => &mut expr.parent,
+            Expression::Slicing(expr) => &mut expr.parent,
+            Expression::Select(expr) => &mut expr.parent,
+            Expression::Literal(expr) => &mut expr.parent,
+            Expression::Cast(expr) => &mut expr.parent,
+            Expression::Call(expr) => &mut expr.parent,
+            Expression::Variable(expr) => &mut expr.parent,
+        }
+    }
+
     pub fn parent_expr_id(&self) -> Option<ExpressionId> {
         if let ExpressionParent::Expression(id, _) = self.parent() {
             Some(*id)
@@ -1875,5 +1901,5 @@ pub struct VariableExpression {
     pub declaration: Option<VariableId>,
     pub used_as_binding_target: bool,
     pub parent: ExpressionParent,
-    pub unique_id_in_definition: i32,
+    pub unique_id_in_definition: i32, // used to index into type table after all types are determined
 }
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