From e5ebc301176352ad476fdfeb122d8403b640bb73 Mon Sep 17 00:00:00 2001
From: Samuel Tardieu <sam@rfc1149.net>
Date: Tue, 17 Sep 2024 19:09:13 +0200
Subject: [PATCH] repo: introduce `MutableRepo::reparent_descendants()`

---
 lib/src/repo.rs | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/lib/src/repo.rs b/lib/src/repo.rs
index 6be4b4fc9c..bd8a33c76b 100644
--- a/lib/src/repo.rs
+++ b/lib/src/repo.rs
@@ -1334,6 +1334,27 @@ impl MutableRepo {
         Ok(num_rebased)
     }
 
+    /// Reparent descendants of the rewritten commits.
+    ///
+    /// The descendants of the commits registered in `self.parent_mappings` will
+    /// be recursively reparented onto the new version of their parents.
+    /// The content of those descendants will remain untouched.
+    /// Returns the number of reparented descendants.
+    pub fn reparent_descendants(&mut self, settings: &UserSettings) -> BackendResult<usize> {
+        let roots = self.parent_mapping.keys().cloned().collect_vec();
+        let mut num_reparented = 0;
+        self.transform_descendants(settings, roots, |rewriter| {
+            if rewriter.parents_changed() {
+                let builder = rewriter.reparent(settings)?;
+                builder.write()?;
+                num_reparented += 1;
+            }
+            Ok(())
+        })?;
+        self.parent_mapping.clear();
+        Ok(num_reparented)
+    }
+
     pub fn rebase_descendants_return_map(
         &mut self,
         settings: &UserSettings,