feat(engine-ecs): add pair macro

1 files changed, 73 insertions, 0 deletions

diff --git a/engine-ecs/src/pair.rs b/engine-ecs/src/pair.rs
index eff0332..cede364 100644
--- a/engine-ecs/src/pair.rs
+++ b/engine-ecs/src/pair.rs
@@ -680,6 +680,79 @@ impl ComponentOrWildcard for Wildcard
 
 impl sealed::Sealed for Wildcard {}
 
+#[macro_export]
+macro_rules! pair {
+    ($relation: ty, $target: ty) => {
+        $crate::pair!(@build, $relation, $target)
+    };
+
+    ($relation: ty, { $target: expr }) => {
+        $crate::pair!(@build, $relation, { $target })
+    };
+
+    ({ $relation: expr }, $target: ty) => {
+        $crate::pair!(@build, { $relation }, $target)
+    };
+
+    ({ $relation: expr }, { $target: expr }) => {
+        $crate::pair!(@build, { $relation }, { $target })
+    };
+
+    ($relation: ty, ={ $target: expr }) => {
+        {
+            fn get_type_uid<T: $crate::pair::ComponentOrWildcard>()
+                -> $crate::uid::Uid
+            {
+                T::uid()
+            }
+
+            $crate::pair::Pair::builder()
+                .relation_id(get_type_uid::<$relation>())
+                .target_as_data({ $target })
+                .build()
+        }
+    };
+
+    (={ $relation: expr }, $target: ty) => {
+        {
+            fn get_type_uid<T: $crate::pair::ComponentOrWildcard>()
+                -> $crate::uid::Uid
+            {
+                T::uid()
+            }
+
+            $crate::pair::Pair::builder()
+                .relation_as_data($relation)
+                .target_id(get_type_uid::<$target>())
+                .build()
+        }
+    };
+
+    (@build, $relation: tt, $target: tt) => {
+        {
+            #[allow(dead_code)]
+            fn get_type_uid<T: $crate::pair::ComponentOrWildcard>()
+                -> $crate::uid::Uid
+            {
+                T::uid()
+            }
+
+            $crate::pair::Pair::builder()
+                .relation_id($crate::pair!(@get_uid, $relation))
+                .target_id($crate::pair!(@get_uid, $target))
+                .build()
+        }
+    };
+
+    (@get_uid, $src: ty) => {
+        get_type_uid::<$src>()
+    };
+
+    (@get_uid, { $src: expr }) => {
+        $src
+    };
+}
+
 mod sealed
 {
     pub trait Sealed {}