feat(ecs): add support for pairs with target component as data

3 files changed, 160 insertions, 55 deletions

diff --git a/ecs/src/lib.rs b/ecs/src/lib.rs
index 979b517..fa31460 100644
--- a/ecs/src/lib.rs
+++ b/ecs/src/lib.rs
@@ -25,7 +25,7 @@ use crate::event::component::{
 };
 use crate::extension::{Collector as ExtensionCollector, Extension};
 use crate::lock::Lock;
-use crate::pair::{ChildOf, DependsOn, Pair};
+use crate::pair::{ChildOf, DependsOn, Pair, Wildcard};
 use crate::phase::{Phase, START as START_PHASE};
 use crate::query::flexible::Query as FlexibleQuery;
 use crate::query::term::Without;
@@ -39,7 +39,7 @@ use crate::query::{
 use crate::sole::Sole;
 use crate::stats::Stats;
 use crate::system::{System, SystemComponent};
-use crate::uid::{Kind as UidKind, Uid, Wildcard};
+use crate::uid::{Kind as UidKind, Uid};
 
 pub mod actions;
 pub mod component;
diff --git a/ecs/src/pair.rs b/ecs/src/pair.rs
index 4ff4995..77b6da7 100644
--- a/ecs/src/pair.rs
+++ b/ecs/src/pair.rs
@@ -1,6 +1,12 @@
+use std::any::type_name;
 use std::convert::Infallible;
 
-use crate::component::{IntoParts as IntoComponentParts, Parts as ComponentParts};
+use crate::component::{
+    Handle as ComponentHandle,
+    HandleMut as ComponentHandleMut,
+    IntoParts as IntoComponentParts,
+    Parts as ComponentParts,
+};
 use crate::entity::{
     Handle as EntityHandle,
     MatchingComponentIter as EntityMatchingComponentIter,
@@ -10,22 +16,22 @@ use crate::query::{
     TermsBuilder as QueryTermsBuilder,
     TermsBuilderInterface,
 };
-use crate::uid::{PairParams as UidPairParams, Uid, Wildcard, With as WithUid};
+use crate::uid::{PairParams as UidPairParams, Uid, With as WithUid};
 use crate::{Component, World};
 
 #[derive(Debug)]
-pub struct Pair<RelationElem: Element, TargetElem: Element>
+pub struct Pair<Relation, Target>
 {
-    relation: RelationElem,
-    target: TargetElem,
+    relation: Relation,
+    target: Target,
 }
 
 impl Pair<Uid, Uid>
 {
     #[must_use]
-    pub fn new<Relation: WithUid>(target: Uid) -> Self
+    pub fn new<Relation: Component>(target: Uid) -> Self
     {
-        Self { relation: Relation::uid(), target }
+        Self { relation: Relation::id(), target }
     }
 
     #[must_use]
@@ -38,6 +44,20 @@ impl Pair<Uid, Uid>
     }
 }
 
+impl<Target> Pair<Uid, Target>
+where
+    Target: Component,
+{
+    /// Returns a new pair that contains the target component as data.
+    pub fn new_with_comp_target<Relation: Component>(target_component: Target) -> Self
+    {
+        Self {
+            relation: Relation::uid(),
+            target: target_component,
+        }
+    }
+}
+
 impl IntoComponentParts for Pair<Uid, Uid>
 {
     fn into_parts(self) -> ComponentParts
@@ -46,12 +66,94 @@ impl IntoComponentParts for Pair<Uid, Uid>
     }
 }
 
-impl<Relation, Target> QueryTermWithField for Pair<Relation, Target>
+impl<Target> IntoComponentParts for Pair<Uid, Target>
+where
+    Target: Component,
+{
+    fn into_parts(self) -> ComponentParts
+    {
+        let id = Uid::new_pair(&UidPairParams {
+            relation: self.relation,
+            target: Target::id(),
+        });
+
+        ComponentParts::builder()
+            .name("Pair")
+            .build(id, self.target)
+    }
+}
+
+impl<Relation, Target> QueryTermWithField for Pair<Relation, &Target>
+where
+    Relation: Component,
+    Target: Component,
+{
+    type Field<'a> = ComponentHandle<'a, Target>;
+
+    fn apply_to_terms_builder<const MAX_TERM_CNT: usize>(
+        terms_builder: &mut QueryTermsBuilder<MAX_TERM_CNT>,
+    )
+    {
+        terms_builder.with_required([Self::uid()]);
+    }
+
+    fn get_field<'world>(
+        entity_handle: &EntityHandle<'world>,
+        _world: &'world World,
+    ) -> Self::Field<'world>
+    {
+        let target_component = entity_handle
+            .get_matching_components(Self::uid())
+            .next()
+            .expect("Not possible");
+
+        Self::Field::from_entity_component_ref(target_component).unwrap_or_else(|err| {
+            panic!(
+                "Creating handle to target component {} failed: {err}",
+                type_name::<Target>()
+            );
+        })
+    }
+}
+
+impl<Relation, Target> QueryTermWithField for Pair<Relation, &mut Target>
+where
+    Relation: Component,
+    Target: Component,
+{
+    type Field<'a> = ComponentHandleMut<'a, Target>;
+
+    fn apply_to_terms_builder<const MAX_TERM_CNT: usize>(
+        terms_builder: &mut QueryTermsBuilder<MAX_TERM_CNT>,
+    )
+    {
+        terms_builder.with_required([Self::uid()]);
+    }
+
+    fn get_field<'world>(
+        entity_handle: &EntityHandle<'world>,
+        _world: &'world World,
+    ) -> Self::Field<'world>
+    {
+        let target_component = entity_handle
+            .get_matching_components(Self::uid())
+            .next()
+            .expect("Not possible");
+
+        Self::Field::from_entity_component_ref(target_component).unwrap_or_else(|err| {
+            panic!(
+                "Creating handle to target component {} failed: {err}",
+                type_name::<Target>()
+            );
+        })
+    }
+}
+
+impl<Relation> QueryTermWithField for Pair<Relation, Wildcard>
 where
-    Relation: WithUid,
-    Target: WithUid,
+    Relation: Component,
 {
-    type Field<'a> = Handle<'a>;
+    type Field<'a> = EntityTargetHandle<'a>;
 
     fn apply_to_terms_builder<const MAX_TERM_CNT: usize>(
         terms_builder: &mut QueryTermsBuilder<MAX_TERM_CNT>,
@@ -70,17 +172,17 @@ where
             .next()
             .expect("Not possible");
 
-        Handle {
+        EntityTargetHandle {
             world,
             pair_uid: first_matching_comp.id(),
         }
     }
 }
 
-impl<Relation, Target> WithUid for Pair<Relation, Target>
+impl<Relation, Target> WithUid for Pair<Relation, &Target>
 where
-    Relation: WithUid,
-    Target: WithUid,
+    Relation: Component,
+    Target: Component,
 {
     fn uid() -> Uid
     {
@@ -91,9 +193,36 @@ where
     }
 }
 
+impl<Relation, Target> WithUid for Pair<Relation, &mut Target>
+where
+    Relation: Component,
+    Target: Component,
+{
+    fn uid() -> Uid
+    {
+        Uid::new_pair(&UidPairParams {
+            relation: Relation::uid(),
+            target: Target::uid(),
+        })
+    }
+}
+
+impl<Relation> WithUid for Pair<Relation, Wildcard>
+where
+    Relation: Component,
+{
+    fn uid() -> Uid
+    {
+        Uid::new_pair(&UidPairParams {
+            relation: Relation::uid(),
+            target: Wildcard::uid(),
+        })
+    }
+}
+
 impl<Relation> QueryTermWithField for &'static [Pair<Relation, Wildcard>]
 where
-    Relation: WithUid,
+    Relation: Component,
 {
     type Field<'a> = HandleIter<'a>;
 
@@ -117,13 +246,13 @@ where
     }
 }
 
-pub struct Handle<'world>
+pub struct EntityTargetHandle<'world>
 {
     world: &'world World,
     pair_uid: Uid,
 }
 
-impl Handle<'_>
+impl EntityTargetHandle<'_>
 {
     #[must_use]
     pub fn get_target_entity(&self) -> Option<EntityHandle<'_>>
@@ -152,38 +281,19 @@ pub struct HandleIter<'a>
 
 impl<'a> Iterator for HandleIter<'a>
 {
-    type Item = Handle<'a>;
+    type Item = EntityTargetHandle<'a>;
 
     fn next(&mut self) -> Option<Self::Item>
     {
         let matching_comp = self.inner.next()?;
 
-        Some(Handle {
+        Some(EntityTargetHandle {
             world: self.world,
             pair_uid: matching_comp.id(),
         })
     }
 }
 
-pub trait Element: sealed::Sealed
-{
-    type Value;
-}
-
-impl Element for Uid
-{
-    type Value = Uid;
-}
-
-impl sealed::Sealed for Uid {}
-
-impl<WithUidT: WithUid> Element for WithUidT
-{
-    type Value = Infallible;
-}
-
-impl<WithUidT: WithUid> sealed::Sealed for WithUidT {}
-
 /// Relation denoting a dependency to another entity
 #[derive(Debug, Default, Clone, Copy, Component)]
 pub struct DependsOn;
@@ -192,7 +302,13 @@ pub struct DependsOn;
 #[derive(Debug, Default, Clone, Copy, Component)]
 pub struct ChildOf;
 
-mod sealed
+#[derive(Debug)]
+pub struct Wildcard(Infallible);
+
+impl Wildcard
 {
-    pub trait Sealed {}
+    pub fn uid() -> Uid
+    {
+        Uid::wildcard()
+    }
 }
diff --git a/ecs/src/uid.rs b/ecs/src/uid.rs
index feed62c..a361882 100644
--- a/ecs/src/uid.rs
+++ b/ecs/src/uid.rs
@@ -218,7 +218,7 @@ pub struct PairParams
     pub target: Uid,
 }
 
-pub trait With: 'static
+pub trait With
 {
     fn uid() -> Uid;
 }
@@ -230,14 +230,3 @@ impl<ComponentT: Component> With for ComponentT
         Self::id()
     }
 }
-
-#[derive(Debug)]
-pub enum Wildcard {}
-
-impl With for Wildcard
-{
-    fn uid() -> Uid
-    {
-        Uid::wildcard()
-    }
-}