Add binary format support for DynamicScene (de)serializers

crates/bevy_scene/Cargo.toml

@@ -26,3 +26,7 @@ ron = "0.8.0"
 uuid = { version = "1.1", features = ["v4", "serde"] }
 anyhow = "1.0.4"
 thiserror = "1.0"
+
+[dev-dependencies]
+postcard = { version = "1.0", features = ["alloc"] }
+bincode = "1.3"

crates/bevy_scene/src/serde.rs

@@ -169,6 +169,22 @@ impl<'a, 'de> Visitor<'de> for SceneEntityVisitor<'a> {
         formatter.write_str("entities")
     }
 
+    fn visit_seq<A>(self, mut seq: A) -> std::result::Result<Self::Value, A::Error>
+    where
+        A: SeqAccess<'de>,
+    {
+        let entity = seq
+            .next_element::<u32>()?
+            .ok_or_else(|| Error::missing_field(ENTITY_FIELD_ENTITY))?;
+        let components = seq
+            .next_element_seed(ComponentVecDeserializer {
+                registry: self.registry,
+            })?
+            .ok_or_else(|| Error::missing_field(ENTITY_FIELD_COMPONENTS))?;
+
+        Ok(DynamicEntity { entity, components })
+    }
+
     fn visit_map<A>(self, mut map: A) -> Result<Self::Value, A::Error>
     where
         A: MapAccess<'de>,
@@ -251,3 +267,234 @@ impl<'a, 'de> Visitor<'de> for ComponentSeqVisitor<'a> {
         Ok(dynamic_properties)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use bevy_app::{App, AppTypeRegistry};
+    use bevy_ecs::prelude::*;
+    use bevy_reflect::{FromReflect, ReflectSerialize};
+    use bincode::Options;
+
+    #[derive(Component, Reflect, Default)]
+    #[reflect(Component)]
+    struct MyComponent {
+        foo: [usize; 3],
+        bar: (f32, f32),
+        baz: MyEnum,
+    }
+
+    #[derive(Reflect, FromReflect, Default)]
+    enum MyEnum {
+        #[default]
+        Unit,
+        Tuple(String),
+        Struct {
+            value: u32,
+        },
+    }
+
+    fn create_app() -> App {
+        let mut app = App::new();
+
+        app.register_type::<MyComponent>();
+        app.register_type::<MyEnum>();
+        app.register_type::<String>();
+        app.register_type_data::<String, ReflectSerialize>();
+        app.register_type::<[usize; 3]>();
+        app.register_type::<(f32, f32)>();
+
+        app.world.spawn(MyComponent {
+            foo: [1, 2, 3],
+            bar: (1.3, 3.7),
+            baz: MyEnum::Tuple("Hello World!".to_string()),
+        });
+
+        app
+    }
+
+    #[test]
+    fn should_roundtrip_postcard() {
+        let app = create_app();
+        let world = app.world;
+        let registry = world.resource::<AppTypeRegistry>();
+
+        let scene = DynamicScene::from_world(&world, registry);
+
+        let scene_serializer = SceneSerializer::new(&scene, &registry.0);
+        let serialized_scene = postcard::to_allocvec(&scene_serializer).unwrap();
+
+        assert_eq!(
+            vec![
+                1, 0, 1, 1, 37, 98, 101, 118, 121, 95, 115, 99, 101, 110, 101, 58, 58, 115, 101,
+                114, 100, 101, 58, 58, 116, 101, 115, 116, 115, 58, 58, 77, 121, 67, 111, 109, 112,
+                111, 110, 101, 110, 116, 1, 2, 3, 102, 102, 166, 63, 205, 204, 108, 64, 1, 12, 72,
+                101, 108, 108, 111, 32, 87, 111, 114, 108, 100, 33
+            ],
+            serialized_scene
+        );
+
+        let scene_deserializer = SceneDeserializer {
+            type_registry: &registry.0.read(),
+        };
+        let deserialized_scene = scene_deserializer
+            .deserialize(&mut postcard::Deserializer::from_bytes(&serialized_scene))
+            .unwrap();
+
+        assert_eq!(1, deserialized_scene.entities.len());
+        assert_scene_eq(&scene, &deserialized_scene);
+    }
+
+    #[test]
+    fn should_roundtrip_bincode() {
+        let app = create_app();
+        let world = app.world;
+        let registry = world.resource::<AppTypeRegistry>();
+
+        let scene = DynamicScene::from_world(&world, registry);
+
+        let scene_serializer = SceneSerializer::new(&scene, &registry.0);
+        let serialized_scene = bincode::serialize(&scene_serializer).unwrap();
+
+        assert_eq!(
+            vec![
+                1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0,
+                37, 0, 0, 0, 0, 0, 0, 0, 98, 101, 118, 121, 95, 115, 99, 101, 110, 101, 58, 58,
+                115, 101, 114, 100, 101, 58, 58, 116, 101, 115, 116, 115, 58, 58, 77, 121, 67, 111,
+                109, 112, 111, 110, 101, 110, 116, 1, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0,
+                3, 0, 0, 0, 0, 0, 0, 0, 102, 102, 166, 63, 205, 204, 108, 64, 1, 0, 0, 0, 12, 0, 0,
+                0, 0, 0, 0, 0, 72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100, 33
+            ],
+            serialized_scene
+        );
+
+        let scene_deserializer = SceneDeserializer {
+            type_registry: &registry.0.read(),
+        };
+
+        let deserialized_scene = bincode::DefaultOptions::new()
+            .with_fixint_encoding()
+            .deserialize_seed(scene_deserializer, &serialized_scene)
+            .unwrap();
+
+        assert_eq!(1, deserialized_scene.entities.len());
+        assert_scene_eq(&scene, &deserialized_scene);
+    }
+
+    /// A crude equality checker for [`DynamicScene`], used solely for testing purposes.
+    fn assert_scene_eq(expected: &DynamicScene, received: &DynamicScene) {
+        assert_eq!(
+            expected.entities.len(),
+            received.entities.len(),
+            "entity count did not match",
+        );
+
+        for expected in &expected.entities {
+            let received = received
+                .entities
+                .iter()
+                .find(|dynamic_entity| dynamic_entity.entity == expected.entity)
+                .unwrap_or_else(|| panic!("missing entity (expected: `{}`)", expected.entity));
+
+            assert_eq!(expected.entity, received.entity, "entities did not match",);
+
+            for expected in &expected.components {
+                let received = received
+                    .components
+                    .iter()
+                    .find(|component| component.type_name() == expected.type_name())
+                    .unwrap_or_else(|| {
+                        panic!("missing component (expected: `{}`)", expected.type_name())
+                    });
+
+                assert!(
+                    expected
+                        .reflect_partial_eq(received.as_ref())
+                        .unwrap_or_default(),
+                    "components did not match: (expected: `{:?}`, received: `{:?}`)",
+                    expected,
+                    received
+                );
+            }
+        }
+    }
+
+    /// These tests just verify that that the [`assert_scene_eq`] function is working properly for our tests.
+    mod assert_scene_eq_tests {
+        use super::*;
+
+        #[test]
+        #[should_panic(expected = "entity count did not match")]
+        fn should_panic_when_entity_count_not_eq() {
+            let mut app = create_app();
+            let world = &mut app.world;
+            let registry = world.resource::<AppTypeRegistry>();
+            let scene_a = DynamicScene::from_world(world, registry);
+
+            world.spawn(MyComponent {
+                foo: [1, 2, 3],
+                bar: (1.3, 3.7),
+                baz: MyEnum::Unit,
+            });
+
+            let registry = world.resource::<AppTypeRegistry>();
+            let scene_b = DynamicScene::from_world(world, registry);
+
+            assert_scene_eq(&scene_a, &scene_b);
+        }
+
+        #[test]
+        #[should_panic(expected = "components did not match")]
+        fn should_panic_when_components_not_eq() {
+            let mut app = create_app();
+            let world = &mut app.world;
+
+            let entity = world
+                .spawn(MyComponent {
+                    foo: [1, 2, 3],
+                    bar: (1.3, 3.7),
+                    baz: MyEnum::Unit,
+                })
+                .id();
+
+            let registry = world.resource::<AppTypeRegistry>();
+            let scene_a = DynamicScene::from_world(world, registry);
+
+            world.entity_mut(entity).insert(MyComponent {
+                foo: [3, 2, 1],
+                bar: (1.3, 3.7),
+                baz: MyEnum::Unit,
+            });
+
+            let registry = world.resource::<AppTypeRegistry>();
+            let scene_b = DynamicScene::from_world(world, registry);
+
+            assert_scene_eq(&scene_a, &scene_b);
+        }
+
+        #[test]
+        #[should_panic(expected = "missing component")]
+        fn should_panic_when_missing_component() {
+            let mut app = create_app();
+            let world = &mut app.world;
+
+            let entity = world
+                .spawn(MyComponent {
+                    foo: [1, 2, 3],
+                    bar: (1.3, 3.7),
+                    baz: MyEnum::Unit,
+                })
+                .id();
+
+            let registry = world.resource::<AppTypeRegistry>();
+            let scene_a = DynamicScene::from_world(world, registry);
+
+            world.entity_mut(entity).remove::<MyComponent>();
+
+            let registry = world.resource::<AppTypeRegistry>();
+            let scene_b = DynamicScene::from_world(world, registry);
+
+            assert_scene_eq(&scene_a, &scene_b);
+        }
+    }
+}