feat(engine): add try_get_field_mut fn to enum variant reflection

1 files changed, 37 insertions, 1 deletions

diff --git a/engine-reflection/src/lib.rs b/engine-reflection/src/lib.rs
index a31fef0..79a7417 100644
--- a/engine-reflection/src/lib.rs
+++ b/engine-reflection/src/lib.rs
@@ -168,12 +168,17 @@ pub struct EnumVariant
         dst: &mut dyn Any,
         fields: &mut dyn Iterator<Item = Box<dyn Any>>,
     ) -> Result<(), EnumVariantWriteNewToError>,
+
+    pub try_get_field_mut: fn(
+        target: &mut dyn Any,
+        field_index: usize,
+    ) -> Result<&mut dyn Any, EnumVariantGetFieldError>,
 }
 
 #[derive(Debug, thiserror::Error)]
 pub enum EnumVariantWriteNewToError
 {
-    #[error("Destination must be the same type as the variant's enum")]
+    #[error("Destination must have the same type as the variant's enum")]
     WrongDstType,
 
     #[error("Too few fields are specified")]
@@ -186,6 +191,19 @@ pub enum EnumVariantWriteNewToError
     WrongFieldType,
 }
 
+#[derive(Debug, thiserror::Error)]
+pub enum EnumVariantGetFieldError
+{
+    #[error("Target is not the same type as the variant's enum")]
+    WrongTargetType,
+
+    #[error("Target is not the correct variant")]
+    WrongTargetVariant,
+
+    #[error("Field index is out of bounds")]
+    FieldIndexOutOfBounds,
+}
+
 #[derive(Debug, Clone)]
 pub enum EnumVariantFields
 {
@@ -468,6 +486,21 @@ unsafe impl<T: Reflection> Reflection for Option<T>
 
                     Ok(())
                 },
+                try_get_field_mut: |target, field_index| {
+                    if field_index != 0 {
+                        return Err(EnumVariantGetFieldError::FieldIndexOutOfBounds);
+                    }
+
+                    let target = target
+                        .downcast_mut::<Self>()
+                        .ok_or(EnumVariantGetFieldError::WrongTargetType)?;
+
+                    let Some(value_field) = target else {
+                        return Err(EnumVariantGetFieldError::WrongTargetVariant);
+                    };
+
+                    Ok(value_field)
+                },
             },
             EnumVariant {
                 name: "None",
@@ -485,6 +518,9 @@ unsafe impl<T: Reflection> Reflection for Option<T>
 
                     Ok(())
                 },
+                try_get_field_mut: |_, _| {
+                    Err(EnumVariantGetFieldError::FieldIndexOutOfBounds)
+                },
             },
         ],
         is_unit_only: false,