From 95b34614054c48145c98a686d9053a2723c6c113 Mon Sep 17 00:00:00 2001
From: Eric Coissac <eric@coissac.eu>
Date: Sat, 6 Jun 2026 04:41:53 +0200
Subject: [PATCH] refactor: centralize graph traversal logic in walk

Refactor `leavable` and `reachable` to eliminate duplicated graph traversal logic by mutually delegating via `WalkState`. `leavable` now returns `self.walk(graph).is_some()`, while `reachable` delegates to the inverted `direct` state's `leavable` check. This centralizes kmer extension and visited-state validation in `walk`, simplifying control flow and reducing code duplication.
---
 src/obidebruinj/src/debruijn.rs | 52 ++-------------------------------
 1 file changed, 3 insertions(+), 49 deletions(-)

diff --git a/src/obidebruinj/src/debruijn.rs b/src/obidebruinj/src/debruijn.rs
index 6c6ec20..6342427 100644
--- a/src/obidebruinj/src/debruijn.rs
+++ b/src/obidebruinj/src/debruijn.rs
@@ -189,58 +189,12 @@ impl WalkState {
     }
 
     pub fn leavable(&self, graph: &GraphDeBruijn) -> bool {
-        WalkState {
-            kmer: self.kmer,
-            node: self.node,
-            direct: !self.direct,
-        }
-        .reachable(graph)
+        self.walk(graph).is_some()
     }
 
     pub fn reachable(&self, graph: &GraphDeBruijn) -> bool {
-        if self.direct {
-            if self.node.can_extend_left() {
-                let next = self.kmer.into_kmer().push_left(self.node.left_nuc());
-                let cnext = next.canonical();
-                let dnext = next.raw() == cnext.raw();
-                let next_node = Node(
-                    graph
-                        .nodes
-                        .get(&cnext)
-                        .unwrap()
-                        .load(std::sync::atomic::Ordering::Relaxed),
-                );
-                !next_node.is_visited()
-                    && if dnext {
-                        next_node.can_extend_right()
-                    } else {
-                        next_node.can_extend_left()
-                    }
-            } else {
-                false
-            }
-        } else {
-            if self.node.can_extend_right() {
-                let next = self.kmer.into_kmer().push_right(self.node.right_nuc());
-                let cnext = next.canonical();
-                let dnext = next.raw() == cnext.raw();
-                let next_node = Node(
-                    graph
-                        .nodes
-                        .get(&cnext)
-                        .unwrap()
-                        .load(std::sync::atomic::Ordering::Relaxed),
-                );
-                !next_node.is_visited()
-                    && if dnext {
-                        next_node.can_extend_left()
-                    } else {
-                        next_node.can_extend_right()
-                    }
-            } else {
-                false
-            }
-        }
+        WalkState { kmer: self.kmer, node: self.node, direct: !self.direct }
+            .leavable(graph)
     }
 
     pub fn walk(&self, graph: &GraphDeBruijn) -> Option<WalkState> {