diff --git a/ast-generator/src/type_gen/struct_type.rs b/ast-generator/src/type_gen/struct_type.rs
index c705a94..8292bdf 100644
--- a/ast-generator/src/type_gen/struct_type.rs
+++ b/ast-generator/src/type_gen/struct_type.rs
@@ -1,4 +1,6 @@
-use crate::spec::struct_spec::{MemberChild, MemberChildBuild, StructChild, StructSpec, VecChild, VecChildBuild};
+use crate::spec::struct_spec::{
+    MemberChild, MemberChildBuild, StructChild, StructSpec, VecChild, VecChildBuild,
+};
 use proc_macro2::{Ident, TokenStream};
 use quote::{format_ident, quote};
 
@@ -11,16 +13,16 @@ fn make_vec_child_accessors(vec_child: &VecChild) -> TokenStream {
                     self.#child_ident.iter().map(String::as_str)
                 }
             }
-        },
+        }
         VecChildBuild::Node(vec_child_node_build) => {
             let child_type_ident = format_ident!("{}", vec_child_node_build.kind());
             let child_ident_mut = format_ident!("{}_mut", vec_child.name());
-            
+
             quote! {
                 pub fn #child_ident(&self) -> impl Iterator<Item = &#child_type_ident> {
                     self.#child_ident.iter().map(Box::as_ref)
                 }
-                
+
                 pub fn #child_ident_mut(&mut self) -> impl Iterator<Item = &mut child_type_ident> {
                     self.#child_ident.iter().map(Box::as_mut)
                 }
@@ -35,7 +37,7 @@ fn make_member_child_accessors(member_child: &MemberChild) -> TokenStream {
         MemberChildBuild::Node(node_member_build) => {
             let return_type_ident = format_ident!("{}", node_member_build.kind());
             let child_ident_mut = format_ident!("{}_mut", member_child.name());
-            
+
             if member_child.optional() {
                 quote! {
                     pub fn #child_ident(&self) -> Option<&#return_type_ident> {
@@ -45,7 +47,7 @@ fn make_member_child_accessors(member_child: &MemberChild) -> TokenStream {
                             None
                         }
                     }
-                    
+
                     pub fn #child_ident_mut(&mut self) -> Option<&mut #return_type_ident> {
                         if let Some(#child_ident) = &mut self.#child_ident {
                             Some(#child_ident.as_mut())
@@ -59,7 +61,7 @@ fn make_member_child_accessors(member_child: &MemberChild) -> TokenStream {
                     pub fn #child_ident(&self) -> &#return_type_ident {
                         self.#child_ident.as_ref()
                     }
-                    
+
                     pub fn #child_ident_mut(&mut self) -> &mut #return_type_ident {
                         self.#child_ident.as_mut()
                     }
@@ -79,24 +81,16 @@ fn make_member_child_accessors(member_child: &MemberChild) -> TokenStream {
 fn make_accessors(child: &StructChild) -> Option<TokenStream> {
     match child {
         StructChild::SkipChild(_) => None,
-        StructChild::VecChild(vec_child) => {
-            Some(make_vec_child_accessors(vec_child))
-        }
-        StructChild::MemberChild(member_child) => {
-            Some(make_member_child_accessors(member_child))
-        }
+        StructChild::VecChild(vec_child) => Some(make_vec_child_accessors(vec_child)),
+        StructChild::MemberChild(member_child) => Some(make_member_child_accessors(member_child)),
     }
 }
 
 fn make_member_ident(child: &StructChild) -> Option<Ident> {
     match child {
         StructChild::SkipChild(_) => None,
-        StructChild::VecChild(vec_child) => {
-            Some(format_ident!("{}", vec_child.name()))
-        },
-        StructChild::MemberChild(member_child) => {
-            Some(format_ident!("{}", member_child.name()))
-        }
+        StructChild::VecChild(vec_child) => Some(format_ident!("{}", vec_child.name())),
+        StructChild::MemberChild(member_child) => Some(format_ident!("{}", member_child.name())),
     }
 }
 
@@ -107,9 +101,9 @@ fn make_vec_child_annotated_member(vec_child: &VecChild) -> TokenStream {
         VecChildBuild::Node(vec_child_node_build) => {
             let type_ident = format_ident!("{}", vec_child_node_build.kind());
             quote! { Box<#type_ident> }
-        },
+        }
     };
-    
+
     quote! {
         #child_ident: Vec<#type_stream>
     }
@@ -120,7 +114,7 @@ fn make_member_child_type_ident(member_child: &MemberChild) -> TokenStream {
         MemberChildBuild::Node(node_member_build) => {
             let type_ident = format_ident!("{}", node_member_build.kind());
             quote! { #type_ident }
-        },
+        }
         MemberChildBuild::Boolean(_) => {
             quote! { bool }
         }
@@ -131,11 +125,11 @@ fn make_member_child_annotated_member(member_child: &MemberChild) -> TokenStream
     let child_name_ident = format_ident!("{}", member_child.name());
     let type_ident = make_member_child_type_ident(member_child);
     let type_stream = if member_child.optional() {
-        quote! { Option<#type_ident> }
+        quote! { Option<Box<#type_ident>> }
     } else {
-        type_ident
+        quote! { Box<#type_ident> }
     };
-    
+
     quote! {
         #child_name_ident: #type_stream
     }
@@ -145,36 +139,35 @@ fn make_annotated_member(child: &StructChild) -> Option<TokenStream> {
     match child {
         StructChild::SkipChild(_) => None,
         StructChild::VecChild(vec_child) => Some(make_vec_child_annotated_member(vec_child)),
-        StructChild::MemberChild(member_child) => Some(make_member_child_annotated_member(member_child)),
+        StructChild::MemberChild(member_child) => {
+            Some(make_member_child_annotated_member(member_child))
+        }
     }
 }
 
 pub fn make_struct_type(build_spec: &StructSpec) -> TokenStream {
     let type_ident = format_ident!("{}", build_spec.build());
-    let annotated_members =  build_spec.children()
-        .map(|child| {
-            make_annotated_member(child)
-        })
+    let annotated_members = build_spec
+        .children()
+        .map(|child| make_annotated_member(child))
         .filter(Option::is_some)
         .map(Option::unwrap)
         .collect::<Vec<_>>();
-    
-    let member_names = build_spec.children()
-        .map(|child| {
-            make_member_ident(child)
-        })
+
+    let member_names = build_spec
+        .children()
+        .map(|child| make_member_ident(child))
         .filter(Option::is_some)
         .map(Option::unwrap)
         .collect::<Vec<_>>();
-    
-    let accessors = build_spec.children()
-        .map(|child| {
-            make_accessors(child)
-        })
+
+    let accessors = build_spec
+        .children()
+        .map(|child| make_accessors(child))
         .filter(Option::is_some)
         .map(Option::unwrap)
         .collect::<Vec<_>>();
-    
+
     quote! {
         pub struct #type_ident {
             #(#annotated_members),*