1 files changed, 56 insertions, 0 deletions
diff --git a/engine-ecs/examples/with_sole.rs b/engine-ecs/examples/with_sole.rs
new file mode 100644
index 0000000..69670d1
--- /dev/null
+++ b/engine-ecs/examples/with_sole.rs
@@ -0,0 +1,56 @@
+use engine_ecs::pair::ChildOf;
+use engine_ecs::phase::{Phase, UPDATE as UPDATE_PHASE};
+use engine_ecs::sole::Single;
+use engine_ecs::{declare_entity, pair, Component, Query, Sole, World};
+
+#[derive(Component)]
+struct Ammo
+{
+    ammo_left: u32,
+}
+
+#[derive(Sole, Default)]
+struct AmmoCounter
+{
+    counter: u32,
+}
+
+fn count_ammo(query: Query<(&Ammo,)>, mut ammo_counter: Single<AmmoCounter>)
+{
+    for (ammo,) in &query {
+        println!("Found {} ammo", ammo.ammo_left);
+
+        ammo_counter.get_mut().unwrap().counter += ammo.ammo_left;
+    }
+}
+
+fn print_total_ammo_count(ammo_counter: Single<AmmoCounter>)
+{
+    let ammo_count = ammo_counter.get().unwrap().counter;
+
+    println!("Total ammo count: {}", ammo_count);
+
+    assert_eq!(ammo_count, 19);
+}
+
+declare_entity! {
+    PRINT_AMMO_COUNT_PHASE: (Phase, pair!(ChildOf, { *UPDATE_PHASE }));
+}
+
+fn main()
+{
+    let mut world = World::new();
+
+    world.spawn_declared_entity(&PRINT_AMMO_COUNT_PHASE);
+
+    world.register_system(*UPDATE_PHASE, count_ammo);
+    world.register_system(*PRINT_AMMO_COUNT_PHASE, print_total_ammo_count);
+
+    world.spawn((Ammo { ammo_left: 4 },));
+    world.spawn((Ammo { ammo_left: 7 },));
+    world.spawn((Ammo { ammo_left: 8 },));
+
+    world.add_sole(AmmoCounter::default()).unwrap();
+
+    world.step();
+}