3 files changed, 29 insertions, 0 deletions
diff --git a/chain/src/atom/default.rs b/chain/src/atom/default.rs
index df61b6f..c6289f1 100644
--- a/chain/src/atom/default.rs
+++ b/chain/src/atom/default.rs
@@ -213,6 +213,11 @@ impl LabelGraph<LabelType<TNT>> for DefaultAtom {
     where
         Self: 'b;
 
+    type TupleIter<'b> = <DefaultNFA<LabelType<TNT>> as LabelGraph<LabelType<TNT>>>::TupleIter<'b>
+    where
+        Self: 'b,
+        DOption<TNT>: 'b;
+
     type LabelIter<'b> = <DefaultNFA<LabelType<TNT>> as LabelGraph<LabelType<TNT>>>::LabelIter<'b>
     where
         Self: 'b,
@@ -247,6 +252,11 @@ impl LabelGraph<LabelType<TNT>> for DefaultAtom {
     }
 
     #[inline]
+    fn tuples_of(&self, node_id: usize) -> Result<Self::TupleIter<'_>, GraphError> {
+        self.nfa.tuples_of(node_id)
+    }
+
+    #[inline]
     fn labels_of(&self, node_id: usize) -> Result<Self::LabelIter<'_>, GraphError> {
         self.nfa.labels_of(node_id)
     }
diff --git a/chain/src/default.rs b/chain/src/default.rs
index 85e3c8f..042f84e 100644
--- a/chain/src/default.rs
+++ b/chain/src/default.rs
@@ -324,6 +324,11 @@ impl LabelGraph<Edge> for DefaultChain {
     where
         Self: 'a;
 
+    type TupleIter<'a> = <DLGraph<Edge> as LabelGraph<Edge>>::TupleIter<'a>
+    where
+        Self: 'a,
+        Edge: 'a;
+
     type LabelIter<'a> = <DLGraph<Edge> as LabelGraph<Edge>>::LabelIter<'a>
     where
         Self: 'a,
@@ -349,6 +354,11 @@ impl LabelGraph<Edge> for DefaultChain {
     }
 
     #[inline]
+    fn tuples_of(&self, node_id: usize) -> Result<Self::TupleIter<'_>, GError> {
+        self.graph.tuples_of(node_id)
+    }
+
+    #[inline]
     fn labels_of(&self, node_id: usize) -> Result<Self::LabelIter<'_>, GError> {
         self.graph.labels_of(node_id)
     }
diff --git a/chain/src/item/default/mod.rs b/chain/src/item/default/mod.rs
index 01e463e..f532805 100644
--- a/chain/src/item/default/mod.rs
+++ b/chain/src/item/default/mod.rs
@@ -127,6 +127,11 @@ impl<T: GraphLabel> LabelGraph<T> for DefaultForest<T> {
     where
         Self: 'a;
 
+    type TupleIter<'a> = std::iter::Empty<(T, usize)>
+    where
+        Self: 'a,
+        T: 'a;
+
     type LabelIter<'a> = std::iter::Empty<(&'a T, <Self as LabelGraph<T>>::Iter<'a>)>
     where
         Self: 'a,
@@ -163,6 +168,10 @@ impl<T: GraphLabel> LabelGraph<T> for DefaultForest<T> {
         unimplemented!("edges have no labels")
     }
 
+    fn tuples_of(&self, _node_id: usize) -> Result<Self::TupleIter<'_>, GError> {
+        unimplemented!("edges have no labels")
+    }
+
     fn labels_of(&self, _node_id: usize) -> Result<Self::LabelIter<'_>, GError> {
         unimplemented!("edges have no labels")
     }