feat(ecs): add support for system local components

1 files changed, 34 insertions, 0 deletions

diff --git a/ecs/src/component.rs b/ecs/src/component.rs
index 4829050..8119e93 100644
--- a/ecs/src/component.rs
+++ b/ecs/src/component.rs
@@ -1,5 +1,6 @@
 use std::any::{Any, TypeId};
 use std::fmt::Debug;
+use std::ops::{Deref, DerefMut};
 
 use seq_macro::seq;
 
@@ -112,3 +113,36 @@ macro_rules! inner {
 seq!(C in 0..=64 {
     inner!(C);
 });
+
+/// Holds a component which is local to a single system.
+#[derive(Debug)]
+pub struct Local<'world, Value>
+{
+    value: &'world mut Value,
+}
+
+impl<'world, Value> Local<'world, Value>
+{
+    pub(crate) fn new(value: &'world mut Value) -> Self
+    {
+        Self { value }
+    }
+}
+
+impl<'world, Value> Deref for Local<'world, Value>
+{
+    type Target = Value;
+
+    fn deref(&self) -> &Self::Target
+    {
+        self.value
+    }
+}
+
+impl<'world, Value> DerefMut for Local<'world, Value>
+{
+    fn deref_mut(&mut self) -> &mut Self::Target
+    {
+        &mut self.value
+    }
+}