From 548cfe53130537dfee33d143e8a563879e30e1a2 Mon Sep 17 00:00:00 2001
From: HampusM <hampus@hampusmat.com>
Date: Wed, 8 Jul 2026 00:42:44 +0200
Subject: feat(engine): add try_get_field_mut fn to enum variant reflection

---
 engine-macros/src/reflection/enum_impl.rs | 80 ++++++++++++++++++++++++++++++-
 1 file changed, 79 insertions(+), 1 deletion(-)

(limited to 'engine-macros/src')

diff --git a/engine-macros/src/reflection/enum_impl.rs b/engine-macros/src/reflection/enum_impl.rs
index 4e27c2b..b637d9f 100644
--- a/engine-macros/src/reflection/enum_impl.rs
+++ b/engine-macros/src/reflection/enum_impl.rs
@@ -273,6 +273,61 @@ fn generate_variants<'a>(
                 }
             };
 
+        let variant_ident = &variant.ident;
+
+        let variant_pattern = match &variant.fields {
+            syn::Fields::Unit => quote! { Self::#variant_ident },
+            syn::Fields::Named(syn::FieldsNamed { named: named_fields, .. }) => {
+                let field_idents = named_fields.iter().map(|field| {
+                    let Some(field_ident) = &field.ident else {
+                        unreachable!();
+                    };
+
+                    field_ident
+                });
+
+                quote! { Self::#variant_ident { #(#field_idents),* } }
+            }
+            syn::Fields::Unnamed(syn::FieldsUnnamed {
+                unnamed: unnamed_fields, ..
+            }) => {
+                let field_idents = unnamed_fields
+                    .iter()
+                    .enumerate()
+                    .map(|(field_index, _)| format_ident!("field_{field_index}"));
+
+                quote! { Self::#variant_ident(#(#field_idents),*) }
+            }
+        };
+
+        let field_index_match_arms = match &variant.fields {
+            syn::Fields::Unit => quote! {},
+            syn::Fields::Named(syn::FieldsNamed { named: named_fields, .. }) => {
+                let match_arms =
+                    named_fields.iter().enumerate().map(|(field_index, field)| {
+                        let Some(field_ident) = &field.ident else {
+                            unreachable!();
+                        };
+
+                        quote! { #field_index => { #field_ident } }
+                    });
+
+                quote! { #(#match_arms)* }
+            }
+            syn::Fields::Unnamed(syn::FieldsUnnamed {
+                unnamed: unnamed_fields, ..
+            }) => {
+                let match_arms =
+                    unnamed_fields.iter().enumerate().map(|(field_index, _)| {
+                        let field_ident = format_ident!("field_{field_index}");
+
+                        quote! { #field_index => { #field_ident } }
+                    });
+
+                quote! { #(#match_arms)* }
+            }
+        };
+
         quote! {
             #engine_crate_path::reflection::EnumVariant {
                 name: #variant_name,
@@ -296,7 +351,30 @@ fn generate_variants<'a>(
                     *dst = created;
 
                     Ok(())
-                }
+                },
+                try_get_field_mut: |target, field_index| { {
+                    #![allow(unreachable_code)]
+
+                    use std::any::Any;
+                    use #engine_crate_path::reflection::EnumVariantGetFieldError;
+
+                    let target = target
+                        .downcast_mut::<Self>()
+                        .ok_or(EnumVariantGetFieldError::WrongTargetType)?;
+
+                    let #variant_pattern = target else {
+                        return Err(EnumVariantGetFieldError::WrongTargetVariant);
+                    };
+
+                    let field: &mut dyn Any = match field_index {
+                        #field_index_match_arms
+                        _ => {
+                            return Err(EnumVariantGetFieldError::FieldIndexOutOfBounds);
+                        }
+                    };
+
+                    Ok(field)
+                } },
             }
         }
     })
-- 
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