impl Debug for Component

src/ecs/component.rs

@@ -95,8 +95,25 @@ impl std::hash::Hash for Component {
     }
 }
 
+impl std::fmt::Debug for Component {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        if self.is_entity() {
+            use super::entity::Entity;
+            unsafe { Entity::from_bits_unchecked(self.to_bits()).fmt(f) }
+        } else if self.is_relation() {
+            use super::relation::Relation;
+            unsafe { Relation::from_bits_unchecked(self.to_bits()).fmt(f) }
+        } else {
+            f.debug_struct("Component")
+                .field("low", &self.low)
+                .field("high", &self.high)
+                .finish()
+        }
+    }
+}
+
 impl Flags {
-    // NOTE: When changing this be sure to update documentation below.
+    // NOTE: When changing this be sure to update documentation.
     pub(crate) const MASK: u32 = 0xF0000000;
 
     /// Extracts only the flags from the specified `u32`.
@@ -162,4 +179,27 @@ mod tests {
         let back_to_relation: Relation = component.try_into().unwrap();
         assert_eq!(relation, back_to_relation);
     }
+
+    #[test]
+    fn debug() {
+        // Component, as long as it's a valid Entity or Relation, will format as such.
+        // In cases where it's neither (not a valid Component), it has a default formatting.
+
+        let entity: Component = Entity::new_checked(69, 1337).unwrap().into();
+        let relation: Component = Relation::new_checked(420, 9001).unwrap().into();
+        let invalid = unsafe { Component::from_bits_unchecked(0x20000000_00000001) };
+
+        assert_eq!(
+            "Entity { id: 69, gen: Generation(1337) }",
+            format!("{entity:?}")
+        );
+        assert_eq!(
+            "Relation { target: 9001, kind: 420 }",
+            format!("{relation:?}")
+        );
+        assert_eq!(
+            "Component { low: 1, high: 536870912 }",
+            format!("{invalid:?}")
+        );
+    }
 }