1 files changed, 47 insertions, 0 deletions
diff --git a/chain/src/archive.txt b/chain/src/archive.txt
index 030ccba..7bd6f31 100644
--- a/chain/src/archive.txt
+++ b/chain/src/archive.txt
@@ -493,3 +493,50 @@
 //         PaVi::Empty => Ok(self.root().ok_or(Error::IndexOutOfBounds(0, 0))?),
 //     }
 // }
+
+// /// Find the last child of the given node whose start and end
+// /// positions contain the given position.  If no such child is
+// /// found, return `Ok(None)`.
+// ///
+// /// The returned tuple is of the form (child, index), where
+// /// `child` is the index of the child node in question, and
+// /// `index` means that the child is the `index`-th child of the
+// /// node.
+// #[allow(dead_code)]
+// pub(crate) fn position_search(
+//     &self,
+//     node: usize,
+//     pos: usize,
+// ) -> Result<Option<(usize, usize)>, Error> {
+//     fn range_contains(label: GrammarLabel, pos: usize) -> bool {
+//         let start = label.start();
+// 
+//         if let Some(end) = label.end() {
+//             (start..end).contains(&pos)
+//         } else {
+//             (start..).contains(&pos)
+//         }
+//     }
+// 
+//     let node_label = self
+//         .vertex_label(node)?
+//         .ok_or(Error::NodeNoLabel(node))?
+//         .label();
+// 
+//     if !range_contains(node_label, pos) {
+//         return Ok(None);
+//     }
+// 
+//     for (index, child) in self.children_of(node)?.enumerate().rev() {
+//         let child_label = self
+//             .vertex_label(child)?
+//             .ok_or(Error::NodeNoLabel(child))?
+//             .label();
+// 
+//         if range_contains(child_label, pos) {
+//             return Ok(Some((child, index)));
+//         }
+//     }
+// 
+//     Ok(None)
+// }