From a735f352f789a440508cf9dd1c554b4d1db6cbb7 Mon Sep 17 00:00:00 2001
From: HampusM <hampus@hampusmat.com>
Date: Tue, 4 Feb 2025 19:04:51 +0100
Subject: fix(ecs): make ComponentRef & ComponentRefMut deref not able to panic

---
 ecs/src/system.rs | 76 ++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 50 insertions(+), 26 deletions(-)

(limited to 'ecs/src/system.rs')

diff --git a/ecs/src/system.rs b/ecs/src/system.rs
index 48c2723..b410d8f 100644
--- a/ecs/src/system.rs
+++ b/ecs/src/system.rs
@@ -13,7 +13,14 @@ use crate::component::{
     FromOptional as FromOptionalComponent,
     FromOptionalMut as FromOptionalMutComponent,
 };
-use crate::lock::{Error as LockError, Lock, ReadGuard, WriteGuard};
+use crate::lock::{
+    Error as LockError,
+    Lock,
+    MappedReadGuard,
+    MappedWriteGuard,
+    ReadGuard,
+    WriteGuard,
+};
 use crate::tuple::{ReduceElement as TupleReduceElement, Tuple};
 use crate::World;
 
@@ -190,7 +197,7 @@ impl<Accumulator> TupleReduceElement<Accumulator, ParamWithInputFilter> for ()
 #[derive(Debug)]
 pub struct ComponentRefMut<'a, ComponentT: Component>
 {
-    inner: WriteGuard<'a, Box<dyn Component>>,
+    inner: MappedWriteGuard<'a, ComponentT>,
     _ph: PhantomData<ComponentT>,
 }
 
@@ -198,7 +205,19 @@ impl<'a, ComponentT: Component> ComponentRefMut<'a, ComponentT>
 {
     pub(crate) fn new(inner: WriteGuard<'a, Box<dyn Component>>) -> Self
     {
-        Self { inner, _ph: PhantomData }
+        Self {
+            inner: inner.map(|component| {
+                let component_type_name = component.type_name();
+
+                component.downcast_mut::<ComponentT>().unwrap_or_else(|| {
+                    panic!(
+                        "Cannot downcast component {component_type_name} to type {}",
+                        type_name::<ComponentT>()
+                    );
+                })
+            }),
+            _ph: PhantomData,
+        }
     }
 }
 
@@ -210,15 +229,12 @@ impl<'component, ComponentT: Component> FromOptionalMutComponent<'component>
         _world: &'component World,
     ) -> Self
     {
-        Self {
-            inner: inner.unwrap_or_else(|| {
-                panic!(
-                    "Component {} was not found in entity",
-                    type_name::<ComponentT>()
-                );
-            }),
-            _ph: PhantomData,
-        }
+        Self::new(inner.unwrap_or_else(|| {
+            panic!(
+                "Component {} was not found in entity",
+                type_name::<ComponentT>()
+            );
+        }))
     }
 }
 
@@ -275,7 +291,7 @@ impl<'a, ComponentT: Component> Deref for ComponentRefMut<'a, ComponentT>
 
     fn deref(&self) -> &Self::Target
     {
-        self.inner.downcast_ref().unwrap()
+        &self.inner
     }
 }
 
@@ -283,14 +299,14 @@ impl<'a, ComponentT: Component> DerefMut for ComponentRefMut<'a, ComponentT>
 {
     fn deref_mut(&mut self) -> &mut Self::Target
     {
-        self.inner.downcast_mut().unwrap()
+        &mut self.inner
     }
 }
 
 #[derive(Debug)]
 pub struct ComponentRef<'a, ComponentT: Component>
 {
-    inner: ReadGuard<'a, Box<dyn Component>>,
+    inner: MappedReadGuard<'a, ComponentT>,
     _ph: PhantomData<ComponentT>,
 }
 
@@ -298,7 +314,18 @@ impl<'a, ComponentT: Component> ComponentRef<'a, ComponentT>
 {
     pub(crate) fn new(inner: ReadGuard<'a, Box<dyn Component>>) -> Self
     {
-        Self { inner, _ph: PhantomData }
+        Self {
+            inner: inner.map(|component| {
+                component.downcast_ref::<ComponentT>().unwrap_or_else(|| {
+                    panic!(
+                        "Cannot downcast component {} to type {}",
+                        component.type_name(),
+                        type_name::<ComponentT>()
+                    );
+                })
+            }),
+            _ph: PhantomData,
+        }
     }
 }
 
@@ -310,15 +337,12 @@ impl<'component, ComponentT: Component> FromOptionalComponent<'component>
         _world: &'component World,
     ) -> Self
     {
-        Self {
-            inner: inner.unwrap_or_else(|| {
-                panic!(
-                    "Component {} was not found in entity",
-                    type_name::<ComponentT>()
-                );
-            }),
-            _ph: PhantomData,
-        }
+        Self::new(inner.unwrap_or_else(|| {
+            panic!(
+                "Component {} was not found in entity",
+                type_name::<ComponentT>()
+            );
+        }))
     }
 }
 
@@ -375,7 +399,7 @@ impl<'a, ComponentT: Component> Deref for ComponentRef<'a, ComponentT>
 
     fn deref(&self) -> &Self::Target
     {
-        self.inner.downcast_ref().unwrap()
+        &self.inner
     }
 }
 
-- 
cgit v1.2.3-18-g5258