Rust: expand derive macros

misc/codegen/templates/rust_classes.mustache

@@ -66,6 +66,20 @@ impl {{name}} {
     pub fn emit_{{singular_field_name}}(id: trap::Label<Self>{{^is_predicate}}{{#is_repeated}}{{^is_unordered}}, i: usize{{/is_unordered}}{{/is_repeated}}, value: {{base_type}}{{/is_predicate}}, out: &mut trap::Writer) {
         out.add_tuple("{{table_name}}", vec![id.into(){{^is_predicate}}{{#is_repeated}}{{^is_unordered}}, i.into(){{/is_unordered}}{{/is_repeated}}, value.into(){{/is_predicate}}]);
     }
+
+    {{#is_repeated}}
+    pub fn emit_{{field_name}}(id: trap::Label<Self>, values: impl IntoIterator<Item={{base_type}}>, out: &mut trap::Writer) {
+        values
+            .into_iter()
+            {{^is_unordered}}
+            .enumerate()
+            .for_each(|(i, value)| Self::emit_{{singular_field_name}}(id, i, value, out));
+            {{/is_unordered}}
+            {{#is_unordered}}
+            .for_each(|value| Self::emit_{{singular_field_name}}(id, value, out));
+            {{/is_unordered}}
+    }
+    {{/is_repeated}}
 {{/detached_fields}}
 }
 {{/has_detached_fields}}

rust/ast-generator/src/main.rs

@@ -385,8 +385,8 @@ struct ExtractorInfo {
 }
 
 fn enum_to_extractor_info(node: &AstEnumSrc) -> Option<ExtractorEnumInfo> {
-    if node.name == "VariantDef" {
-        // currently defined but unused
+    if matches!(node.name.as_str(), "VariantDef" | "Adt") {
+        // these are not used as types of fields, so we don't need to generate extractors for them
         return None;
     }
     Some(ExtractorEnumInfo {
@@ -485,8 +485,6 @@ fn main() -> anyhow::Result<()> {
         .expect("Failed to parse grammar");
     let mut grammar = codegen::grammar::lower(&grammar);
 
-    grammar.enums.retain(|x| x.name != "Adt");
-
     let mut super_types: BTreeMap<String, BTreeSet<String>> = BTreeMap::new();
     for node in &grammar.enums {
         for variant in &node.variants {