1 files changed, 71 insertions, 2 deletions

diff --git a/ecs/src/lib.rs b/ecs/src/lib.rs
index df46a5a..84009e0 100644
--- a/ecs/src/lib.rs
+++ b/ecs/src/lib.rs
@@ -1,6 +1,6 @@
 #![deny(clippy::all, clippy::pedantic)]
 
-use std::any::TypeId;
+use std::any::{Any, TypeId};
 use std::collections::{HashMap, HashSet};
 use std::fmt::Debug;
 use std::hash::Hash;
@@ -8,7 +8,12 @@ use std::marker::PhantomData;
 use std::slice::IterMut as SliceIterMut;
 
 use crate::component::{Component, Sequence as ComponentSequence};
-use crate::system::{System, TypeErased as TypeErasedSystem};
+use crate::system::{
+    NoInitParamFlag as NoInitSystemParamFlag,
+    Param as SystemParam,
+    System,
+    TypeErased as TypeErasedSystem,
+};
 
 pub mod component;
 pub mod system;
@@ -142,6 +147,70 @@ where
     }
 }
 
+unsafe impl<'world, Comps> SystemParam<'world> for Query<'world, Comps>
+where
+    Comps: ComponentSequence,
+{
+    type Flags = NoInitSystemParamFlag;
+    type Input = ();
+
+    fn initialize<SystemImpl>(_system: &mut impl System<SystemImpl>, _input: Self::Input)
+    {
+    }
+
+    fn new<SystemImpl>(
+        _system: &'world mut impl System<SystemImpl>,
+        component_storage: &'world mut ComponentStorage,
+    ) -> Self
+    {
+        Self::new(component_storage)
+    }
+
+    fn is_compatible<Other: SystemParam<'world>>() -> bool
+    {
+        let other_comparable = Other::get_comparable();
+
+        let Some(other_query_component_ids) =
+            other_comparable.downcast_ref::<QueryComponentIds>()
+        else {
+            return true;
+        };
+
+        !other_query_component_ids.contains_component_in::<Comps>()
+    }
+
+    fn get_comparable() -> Box<dyn Any>
+    {
+        Box::new(QueryComponentIds {
+            component_type_ids: Comps::type_ids(),
+        })
+    }
+}
+
+#[derive(Debug)]
+struct QueryComponentIds
+{
+    component_type_ids: Vec<TypeId>,
+}
+
+impl QueryComponentIds
+{
+    fn contains_component_in<OtherComps>(&self) -> bool
+    where
+        OtherComps: ComponentSequence,
+    {
+        let other_component_type_ids = OtherComps::type_ids()
+            .into_iter()
+            .collect::<HashSet<TypeId>>();
+
+        // TODO: Make this a bit smarter. Queries with a same component can be compatible
+        // if one of the queries have a component the other one does not have
+        self.component_type_ids
+            .iter()
+            .any(|component_type_id| other_component_type_ids.contains(component_type_id))
+    }
+}
+
 pub struct QueryComponentIter<'world, Comps>
 {
     entity_iter: SliceIterMut<'world, Entity>,