Add World::iter_resources() and World::iter_resources_mut() methods

crates/bevy_ecs/src/world/mod.rs

@@ -2184,6 +2184,53 @@ impl World {
                 .get_mut_by_id(component_id)
         }
     }
+
+    /// Iterates over all resources in the world
+    pub fn iter_resources(&self) -> impl Iterator<Item = (&ComponentInfo, Ptr<'_>)> {
+        self.storages.resources.iter().map(|(component_id, data)| {
+            let component_info = self.components.get_info(component_id).unwrap_or_else(|| {
+                panic!("ComponentInfo should exist for all resources in the world, but it does not for {:?}", component_id);
+            });
+            let ptr = data.get_data().unwrap_or_else(|| {
+                panic!(
+                    "When iterating all resources, resource of type {} was supposed to exist, but did not.",
+                    component_info.name()
+                )
+            });
+            (component_info, ptr)
+        })
+    }
+
+    /// Mutably iterates over all resources in the world
+    pub fn iter_resources_mut(&mut self) -> impl Iterator<Item = (&ComponentInfo, MutUntyped<'_>)> {
+        self.storages.resources.iter().map(|(component_id, data)| {
+            let component_info = self.components.get_info(component_id).unwrap_or_else(|| {
+                panic!("ComponentInfo should exist for all resources in the world, but it does not for {:?}", component_id);
+            });
+
+            let (ptr, ticks) = data.get_with_ticks().unwrap_or_else(|| {
+                panic!(
+                    "When iterating all resources, resource of type {} was supposed to exist, but did not.",
+                    component_info.name()
+                )
+            });
+
+            // SAFETY:
+            // - ???
+            let ticks = unsafe {
+                TicksMut::from_tick_cells(ticks, self.last_change_tick(), self.read_change_tick())
+            };
+
+            let mut_untyped = MutUntyped {
+                // SAFETY:
+                // - ???
+                value: unsafe { ptr.assert_unique() },
+                ticks,
+            };
+
+            (component_info, mut_untyped)
+        })
+    }
 }
 
 // Schedule-related methods
@@ -2495,6 +2542,9 @@ mod tests {
     #[derive(Resource)]
     struct TestResource(u32);
 
+    #[derive(Resource)]
+    struct TestResource2(String);
+
     #[test]
     fn get_resource_by_id() {
         let mut world = World::new();
@@ -2796,4 +2846,57 @@ mod tests {
         let mut world = World::new();
         world.spawn(());
     }
+
+    #[test]
+    fn iterate_resources() {
+        let mut world = World::new();
+
+        world.insert_resource(TestResource(42));
+        world.insert_resource(TestResource2("Hello, world!".to_string()));
+
+        let mut iter = world.iter_resources();
+
+        let (info, ptr) = iter.next().unwrap();
+        assert_eq!(info.name(), std::any::type_name::<TestResource>());
+        assert_eq!(unsafe { ptr.deref::<TestResource>().0 }, 42);
+
+        let (info, ptr) = iter.next().unwrap();
+        assert_eq!(info.name(), std::any::type_name::<TestResource2>());
+        assert_eq!(
+            unsafe { &ptr.deref::<TestResource2>().0 },
+            &"Hello, world!".to_string()
+        );
+
+        assert!(iter.next().is_none());
+    }
+
+    #[test]
+    fn iterate_resources_mut() {
+        let mut world = World::new();
+
+        world.insert_resource(TestResource(42));
+        world.insert_resource(TestResource2("Hello, world!".to_string()));
+
+        let mut iter = world.iter_resources_mut();
+
+        let (info, mut mut_untyped) = iter.next().unwrap();
+        assert_eq!(info.name(), std::any::type_name::<TestResource>());
+        unsafe { mut_untyped.as_mut().deref_mut::<TestResource>().0 = 43 };
+
+        let (info, mut mut_untyped) = iter.next().unwrap();
+        assert_eq!(info.name(), std::any::type_name::<TestResource2>());
+        unsafe {
+            mut_untyped.as_mut().deref_mut::<TestResource2>().0 = "Hello, world?".to_string()
+        };
+
+        assert!(iter.next().is_none());
+
+        std::mem::drop(iter);
+
+        assert_eq!(world.resource::<TestResource>().0, 43);
+        assert_eq!(
+            world.resource::<TestResource2>().0,
+            "Hello, world?".to_string()
+        );
+    }
 }