Add grab method for EntityMut and EntityWorldMut that consume self.

The grab methods returns access with the world lifetime instead of
&'_ self lifetime.

Methods implemented:
- EntityMut::grab
- EntityMut::grab_ref
- EntityMut::grab_mut
- EntityMut::grab_by_id
- EntityMut::grab_mut_by_id
- EntityWorldMut::grab
- EntityWorldMut::grab_ref
- EntityWorldMut::grab_mut
- EntityWorldMut::grab_by_id
- EntityWorldMut::grab_mut_by_id

crates/bevy_ecs/src/world/entity_ref.rs

@@ -348,6 +348,16 @@ impl<'w> EntityMut<'w> {
         self.as_readonly().get()
     }
 
+    /// Consumes `self` and gets access to the component of type `T` with the
+    /// world `'w` lifetime for the current entity.
+    ///
+    /// Returns `None` if the entity does not have a component of type `T`.
+    #[inline]
+    pub fn grab<T: Component>(self) -> Option<&'w T> {
+        // SAFETY: consuming `self` implies exclusive access
+        unsafe { self.0.get() }
+    }
+
     /// Gets access to the component of type `T` for the current entity,
     /// including change detection information as a [`Ref`].
     ///
@@ -357,6 +367,17 @@ impl<'w> EntityMut<'w> {
         self.as_readonly().get_ref()
     }
 
+    /// Consumes `self` and gets access to the component of type `T` with world
+    /// `'w` lifetime for the current entity, including change detection information
+    /// as a [`Ref<'w>`].
+    ///
+    /// Returns `None` if the entity does not have a component of type `T`.
+    #[inline]
+    pub fn grab_ref<T: Component>(self) -> Option<Ref<'w, T>> {
+        // SAFETY: consuming `self` implies exclusive access
+        unsafe { self.0.get_ref() }
+    }
+
     /// Gets mutable access to the component of type `T` for the current entity.
     /// Returns `None` if the entity does not have a component of type `T`.
     #[inline]
@@ -365,6 +386,15 @@ impl<'w> EntityMut<'w> {
         unsafe { self.0.get_mut() }
     }
 
+    /// Consumes self and gets mutable access to the component of type `T`
+    /// with the world `'w` lifetime for the current entity.
+    /// Returns `None` if the entity does not have a component of type `T`.
+    #[inline]
+    pub fn grab_mut<T: Component>(self) -> Option<Mut<'w, T>> {
+        // SAFETY: consuming `self` implies exclusive access
+        unsafe { self.0.get_mut() }
+    }
+
     /// Retrieves the change ticks for the given component. This can be useful for implementing change
     /// detection in custom runtimes.
     #[inline]
@@ -396,6 +426,19 @@ impl<'w> EntityMut<'w> {
         self.as_readonly().get_by_id(component_id)
     }
 
+    /// Consumes `self` and gets the component of the given [`ComponentId`] with
+    /// world `'w` lifetime from the entity.
+    ///
+    /// **You should prefer to use the typed API [`EntityWorldMut::grab`] where possible and only
+    /// use this in cases where the actual component types are not known at
+    /// compile time.**
+    #[inline]
+    pub fn grab_by_id(self, component_id: ComponentId) -> Option<Ptr<'w>> {
+        // SAFETY:
+        // consuming `self` ensures that no references exist to this entity's components.
+        unsafe { self.0.get_by_id(component_id) }
+    }
+
     /// Gets a [`MutUntyped`] of the component of the given [`ComponentId`] from the entity.
     ///
     /// **You should prefer to use the typed API [`EntityMut::get_mut`] where possible and only
@@ -411,6 +454,19 @@ impl<'w> EntityMut<'w> {
         // - `as_unsafe_world_cell` gives mutable permission for all components on this entity
         unsafe { self.0.get_mut_by_id(component_id) }
     }
+
+    /// Consumes `self` and gets a [`MutUntyped<'w>`] of the component of the given [`ComponentId`]
+    /// with world lifetime from the entity.
+    ///
+    /// **You should prefer to use the typed API [`EntityMut::grab_mut`] where possible and only
+    /// use this in cases where the actual component types are not known at
+    /// compile time.**
+    #[inline]
+    pub fn grab_mut_by_id(self, component_id: ComponentId) -> Option<MutUntyped<'w>> {
+        // SAFETY:
+        // consuming `self` ensures that no references exist to this entity's components.
+        unsafe { self.0.get_mut_by_id(component_id) }
+    }
 }
 
 impl<'w> From<EntityWorldMut<'w>> for EntityMut<'w> {
@@ -583,6 +639,15 @@ impl<'w> EntityWorldMut<'w> {
         EntityRef::from(self).get()
     }
 
+    /// Consumes `self` and gets access to the component of type `T` with
+    /// the world `'w` lifetime for the current entity.
+    /// Returns `None` if the entity does not have a component of type `T`.
+    #[inline]
+    pub fn grab<T: Component>(self) -> Option<&'w T> {
+        // SAFETY: consuming `self` implies exclusive access
+        unsafe { self.into_unsafe_entity_cell().get() }
+    }
+
     /// Gets access to the component of type `T` for the current entity,
     /// including change detection information as a [`Ref`].
     ///
@@ -592,6 +657,16 @@ impl<'w> EntityWorldMut<'w> {
         EntityRef::from(self).get_ref()
     }
 
+    /// Consumes `self` and gets access to the component of type `T`
+    /// with the world `'w` lifetime for the current entity,
+    /// including change detection information as a [`Ref`].
+    ///
+    /// Returns `None` if the entity does not have a component of type `T`.
+    #[inline]
+    pub fn grab_ref<T: Component>(self) -> Option<Ref<'w, T>> {
+        EntityRef::from(self).get_ref()
+    }
+
     /// Gets mutable access to the component of type `T` for the current entity.
     /// Returns `None` if the entity does not have a component of type `T`.
     #[inline]
@@ -600,6 +675,15 @@ impl<'w> EntityWorldMut<'w> {
         unsafe { self.as_unsafe_entity_cell().get_mut() }
     }
 
+    /// Consumes `self` and gets mutable access to the component of type `T`
+    /// with the world `'w` lifetime for the current entity.
+    /// Returns `None` if the entity does not have a component of type `T`.
+    #[inline]
+    pub fn grab_mut<T: Component>(self) -> Option<Mut<'w, T>> {
+        // SAFETY: consuming `self` implies exclusive access
+        unsafe { self.into_unsafe_entity_cell().get_mut() }
+    }
+
     /// Retrieves the change ticks for the given component. This can be useful for implementing change
     /// detection in custom runtimes.
     #[inline]
@@ -631,6 +715,18 @@ impl<'w> EntityWorldMut<'w> {
         EntityRef::from(self).get_by_id(component_id)
     }
 
+    /// Consumes `self` and gets the component of the given [`ComponentId`] with
+    /// with world `'w` lifetime from the entity.
+    ///
+    /// **You should prefer to use the typed API [`EntityWorldMut::grab`] where possible and only
+    /// use this in cases where the actual component types are not known at
+    /// compile time.**
+    #[inline]
+    pub fn grab_by_id(self, component_id: ComponentId) -> Option<Ptr<'w>> {
+        // SAFETY: consuming `self` implies exclusive access
+        unsafe { self.into_unsafe_entity_cell().get_by_id(component_id) }
+    }
+
     /// Gets a [`MutUntyped`] of the component of the given [`ComponentId`] from the entity.
     ///
     /// **You should prefer to use the typed API [`EntityWorldMut::get_mut`] where possible and only
@@ -647,6 +743,19 @@ impl<'w> EntityWorldMut<'w> {
         unsafe { self.as_unsafe_entity_cell().get_mut_by_id(component_id) }
     }
 
+    /// Consumes `self` and gets a [`MutUntyped<'w>`] of the component with the world `'w` lifetime
+    /// of the given [`ComponentId`] from the entity.
+    ///
+    /// **You should prefer to use the typed API [`EntityWorldMut::grab_mut`] where possible and only
+    /// use this in cases where the actual component types are not known at
+    /// compile time.**
+    #[inline]
+    pub fn grab_mut_by_id(self, component_id: ComponentId) -> Option<MutUntyped<'w>> {
+        // SAFETY:
+        // consuming `self` ensures that no references exist to this entity's components.
+        unsafe { self.into_unsafe_entity_cell().get_mut_by_id(component_id) }
+    }
+
     /// Adds a [`Bundle`] of components to the entity.
     ///
     /// This will overwrite any previous value(s) of the same component type.