From 21c8293db6270bd3656775a0ca7dfa9d9c297159 Mon Sep 17 00:00:00 2001
From: bsbds <69835502+bsbds@users.noreply.github.com>
Date: Thu, 21 Mar 2024 09:02:01 +0800
Subject: [PATCH] refactor: use breadth-first search in find all overlap in
 interval tree

Signed-off-by: bsbds <69835502+bsbds@users.noreply.github.com>
---
 crates/utils/src/interval_map/mod.rs | 37 +++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/crates/utils/src/interval_map/mod.rs b/crates/utils/src/interval_map/mod.rs
index 030eaea13..16ba372d2 100644
--- a/crates/utils/src/interval_map/mod.rs
+++ b/crates/utils/src/interval_map/mod.rs
@@ -1,3 +1,5 @@
+use std::collections::VecDeque;
+
 use petgraph::graph::{DefaultIx, IndexType, NodeIndex};
 
 #[cfg(test)]
@@ -79,7 +81,7 @@ where
         if self.node_ref(self.root, Node::is_sentinel) {
             Vec::new()
         } else {
-            self.find_all_overlap_inner(self.root, interval)
+            self.find_all_overlap_inner_unordered(self.root, interval)
         }
     }
 
@@ -289,6 +291,7 @@ where
     }
 
     /// Finds all intervals in the map that overlaps with the given interval.
+    #[cfg(interval_tree_find_overlap_ordered)]
     fn find_all_overlap_inner(
         &self,
         x: NodeIndex<Ix>,
@@ -311,6 +314,38 @@ where
         list
     }
 
+    /// Finds all intervals in the map that overlaps with the given interval.
+    ///
+    /// The result is unordered because of breadth-first search to save stack size
+    fn find_all_overlap_inner_unordered(
+        &self,
+        x: NodeIndex<Ix>,
+        interval: &Interval<T>,
+    ) -> Vec<(&Interval<T>, &V)> {
+        let mut list = Vec::new();
+        let mut queue = VecDeque::new();
+        queue.push_back(x);
+        while let Some(p) = queue.pop_front() {
+            if self.node_ref(p, Node::interval).overlap(interval) {
+                list.push(self.node_ref(p, |np| (np.interval(), np.value())));
+            }
+            let p_left = self.node_ref(p, Node::left);
+            let p_right = self.node_ref(p, Node::right);
+            if self.max(p_left) >= Some(&interval.low) {
+                queue.push_back(p_left);
+            }
+            if self
+                .max(self.node_ref(p, Node::right))
+                .map(|rmax| IntervalRef::new(&self.node_ref(p, Node::interval).low, rmax))
+                .is_some_and(|i| i.overlap(interval))
+            {
+                queue.push_back(p_right);
+            }
+        }
+
+        list
+    }
+
     /// Search for an interval that overlaps with the given interval.
     fn search(&self, interval: &Interval<T>) -> NodeIndex<Ix> {
         let mut x = self.root;