From 73318f39273df3080297eb402f77e66badf0c9f2 Mon Sep 17 00:00:00 2001
From: Martin Junghanns <m.junghanns@mailbox.org>
Date: Fri, 17 Nov 2023 12:53:43 +0100
Subject: [PATCH] Derive node count from node values if present

---
 crates/builder/src/graph/csr.rs | 55 ++++++++++++++++++++++++++++++---
 1 file changed, 50 insertions(+), 5 deletions(-)

diff --git a/crates/builder/src/graph/csr.rs b/crates/builder/src/graph/csr.rs
index 5b37270..346cb25 100644
--- a/crates/builder/src/graph/csr.rs
+++ b/crates/builder/src/graph/csr.rs
@@ -543,13 +543,14 @@ where
 {
     fn from((node_values, edge_list, csr_option): (NodeValues<NV>, E, CsrLayout)) -> Self {
         info!("Creating directed graph");
-        let node_count = edge_list.max_node_id() + NI::new(1);
+        let node_count = NI::new(node_values.0.len());
+        let node_count_from_edge_list = edge_list.max_node_id() + NI::new(1);
 
         assert!(
-            node_values.0.len() >= node_count.index(),
+            node_count >= node_count_from_edge_list,
             "number of node values ({}) does not match node count of edge list ({})",
-            node_values.0.len(),
-            node_count.index()
+            node_count.index(),
+            node_count_from_edge_list.index()
         );
 
         let start = Instant::now();
@@ -743,7 +744,15 @@ where
 {
     fn from((node_values, edge_list, csr_option): (NodeValues<NV>, E, CsrLayout)) -> Self {
         info!("Creating undirected graph");
-        let node_count = edge_list.max_node_id() + NI::new(1);
+        let node_count = NI::new(node_values.0.len());
+        let node_count_from_edge_list = edge_list.max_node_id() + NI::new(1);
+
+        assert!(
+            node_count >= node_count_from_edge_list,
+            "number of node values ({}) does not match node count of edge list ({})",
+            node_count.index(),
+            node_count_from_edge_list.index()
+        );
 
         let start = Instant::now();
         let csr = Csr::from((&edge_list, node_count, Direction::Undirected, csr_option));
@@ -1193,4 +1202,40 @@ mod tests {
             assert_eq!(ug.neighbors(0).as_slice(), &[1, 3, 7, 21, 42]);
         });
     }
+
+    #[test]
+    fn directed_from_node_values_exceeding_edge_list_max_id() {
+        let g0: DirectedCsrGraph<u32, u32> = GraphBuilder::new()
+            .edges(vec![(0, 1), (1, 2)])
+            .node_values(vec![0, 1, 2, 3])
+            .build();
+
+        assert_eq!(g0.node_count(), 4);
+        for node in 0..4 {
+            assert_eq!(g0.node_value(node), &node);
+        }
+
+        assert_eq!(g0.out_degree(0), 1);
+        assert_eq!(g0.out_degree(1), 1);
+        assert_eq!(g0.out_degree(2), 0);
+        assert_eq!(g0.out_degree(3), 0);
+    }
+
+    #[test]
+    fn undirected_from_node_values_exceeding_edge_list_max_id() {
+        let g0: UndirectedCsrGraph<u32, u32> = GraphBuilder::new()
+            .edges(vec![(0, 1), (1, 2)])
+            .node_values(vec![0, 1, 2, 3])
+            .build();
+
+        assert_eq!(g0.node_count(), 4);
+        for node in 0..4 {
+            assert_eq!(g0.node_value(node), &node);
+        }
+
+        assert_eq!(g0.degree(0), 1);
+        assert_eq!(g0.degree(1), 2);
+        assert_eq!(g0.degree(2), 1);
+        assert_eq!(g0.degree(3), 0);
+    }
 }