Codegen: add const overload of forEachLabel

Author: redsun82

misc/codegen/templates/cpp_classes_h.mustache

@@ -42,34 +42,12 @@ struct {{name}}{{#has_bases}} : {{#bases}}{{^first}}, {{/first}}{{ref.name}}{{/b
  {{/final}}
   template <typename F>
   void forEachLabel(F f) {
-    {{#final}}
-    f("id", -1, id);
-    {{/final}}
-    {{#bases}}
-    {{ref.name}}::forEachLabel(f);
-    {{/bases}}
-    {{#fields}}
-    {{#is_label}}
-    {{#is_repeated}}
-    for (auto i = 0u; i < {{field_name}}.size(); ++i) {
-      {{#is_optional}}
-      if ({{field_name}}[i]) f("{{field_name}}", i, *{{field_name}}[i]);
-      {{/is_optional}}
-      {{^is_optional}}
-      f("{{field_name}}", i, {{field_name}}[i]);
-      {{/is_optional}}
-    }
-    {{/is_repeated}}
-    {{^is_repeated}}
-    {{#is_optional}}
-    if ({{field_name}}) f("{{field_name}}", -1, *{{field_name}});
-    {{/is_optional}}
-    {{^is_optional}}
-    f("{{field_name}}", -1, {{field_name}});
-    {{/is_optional}}
-    {{/is_repeated}}
-    {{/is_label}}
-    {{/fields}}
+    {{>cpp_for_each_label_body}}
+  }
+
+  template <typename F>
+  void forEachLabel(F f) const {
+    {{>cpp_for_each_label_body}}
   }
 
  protected:

misc/codegen/templates/cpp_for_each_label_body.mustache

@@ -0,0 +1,28 @@
+{{#final}}
+f("id", -1, id);
+{{/final}}
+{{#bases}}
+{{ref.name}}::forEachLabel(f);
+{{/bases}}
+{{#fields}}
+{{#is_label}}
+{{#is_repeated}}
+for (auto i = 0u; i < {{field_name}}.size(); ++i) {
+  {{#is_optional}}
+  if ({{field_name}}[i]) f("{{field_name}}", i, *{{field_name}}[i]);
+  {{/is_optional}}
+  {{^is_optional}}
+  f("{{field_name}}", i, {{field_name}}[i]);
+  {{/is_optional}}
+}
+{{/is_repeated}}
+{{^is_repeated}}
+{{#is_optional}}
+if ({{field_name}}) f("{{field_name}}", -1, *{{field_name}});
+{{/is_optional}}
+{{^is_optional}}
+f("{{field_name}}", -1, {{field_name}});
+{{/is_optional}}
+{{/is_repeated}}
+{{/is_label}}
+{{/fields}}

misc/codegen/templates/trap_traps_h.mustache

@@ -23,11 +23,12 @@ struct {{name}}Trap {
 
   template <typename F>
   void forEachLabel(F f) {
-    {{#fields}}
-    {{#is_label}}
-    f("{{field_name}}", -1, {{field_name}});
-    {{/is_label}}
-    {{/fields}}
+    {{>cpp_for_each_label_body}}
+  }
+
+  template <typename F>
+  void forEachLabel(F f) const {
+    {{>cpp_for_each_label_body}}
   }
 };