feat(ecs): add support for multiple system queries & local components

1 files changed, 52 insertions, 2 deletions

diff --git a/ecs/src/component.rs b/ecs/src/component.rs
index bead3b5..59b737e 100644
--- a/ecs/src/component.rs
+++ b/ecs/src/component.rs
@@ -4,6 +4,9 @@ use std::ops::{Deref, DerefMut};
 
 use seq_macro::seq;
 
+use crate::system::{Input as SystemInput, Param as SystemParam, System};
+use crate::ComponentStorage;
+
 pub trait Component: Any
 {
     #[doc(hidden)]
@@ -114,20 +117,65 @@ seq!(C in 0..=64 {
 
 /// Holds a component which is local to a single system.
 #[derive(Debug)]
-pub struct Local<'world, Value>
+pub struct Local<'world, Value: SystemInput>
 {
     value: &'world mut Value,
 }
 
 impl<'world, Value> Local<'world, Value>
+where
+    Value: SystemInput,
 {
-    pub(crate) fn new(value: &'world mut Value) -> Self
+    fn new(value: &'world mut Value) -> Self
     {
         Self { value }
     }
 }
 
+unsafe impl<'world, Value: 'static> SystemParam<'world> for Local<'world, Value>
+where
+    Value: SystemInput,
+{
+    type Flags = ();
+    type Input = Value;
+
+    fn initialize<SystemImpl>(system: &mut impl System<SystemImpl>, input: Self::Input)
+    {
+        system.set_local_component(input);
+    }
+
+    fn new<SystemImpl>(
+        system: &'world mut impl System<SystemImpl>,
+        _component_storage: &'world mut ComponentStorage,
+    ) -> Self
+    {
+        let local_component = system
+            .get_local_component_mut::<Value>()
+            .expect("Local component is uninitialized");
+
+        Self::new(local_component)
+    }
+
+    fn is_compatible<Other: SystemParam<'world>>() -> bool
+    {
+        let other_comparable = Other::get_comparable();
+
+        let Some(other_type_id) = other_comparable.downcast_ref::<TypeId>() else {
+            return true;
+        };
+
+        TypeId::of::<Value>() != *other_type_id
+    }
+
+    fn get_comparable() -> Box<dyn Any>
+    {
+        Box::new(TypeId::of::<Value>())
+    }
+}
+
 impl<'world, Value> Deref for Local<'world, Value>
+where
+    Value: SystemInput,
 {
     type Target = Value;
 
@@ -138,6 +186,8 @@ impl<'world, Value> Deref for Local<'world, Value>
 }
 
 impl<'world, Value> DerefMut for Local<'world, Value>
+where
+    Value: SystemInput,
 {
     fn deref_mut(&mut self) -> &mut Self::Target
     {