From 9946e52fdfa5b2f553bf2789018b307889677411 Mon Sep 17 00:00:00 2001
From: Martin von Zweigbergk <martinvonz@google.com>
Date: Thu, 21 Sep 2023 11:39:41 -0700
Subject: [PATCH] tree: leverage `Merge::try_map()` when reading file contents
 to merge

---
 lib/src/tree.rs | 26 ++++++--------------------
 1 file changed, 6 insertions(+), 20 deletions(-)

diff --git a/lib/src/tree.rs b/lib/src/tree.rs
index 73ced72a0..a977bd8ba 100644
--- a/lib/src/tree.rs
+++ b/lib/src/tree.rs
@@ -433,9 +433,7 @@ pub fn try_resolve_file_conflict(
             executable,
         }));
     }
-    let mut removed_contents = vec![];
-    let mut added_contents = vec![];
-    for &file_id in file_id_conflict.removes() {
+    let contents = file_id_conflict.try_map(|&file_id| -> Result<Vec<u8>, TreeMergeError> {
         let mut content = vec![];
         store
             .read_file(filename, file_id)?
@@ -444,23 +442,11 @@ pub fn try_resolve_file_conflict(
                 source: err,
                 file_id: file_id.clone(),
             })?;
-        removed_contents.push(content);
-    }
-    for &file_id in file_id_conflict.adds() {
-        let mut content = vec![];
-        store
-            .read_file(filename, file_id)?
-            .read_to_end(&mut content)
-            .map_err(|err| TreeMergeError::ReadError {
-                source: err,
-                file_id: file_id.clone(),
-            })?;
-        added_contents.push(content);
-    }
-    let merge_result = files::merge(
-        &removed_contents.iter().map(Vec::as_slice).collect_vec(),
-        &added_contents.iter().map(Vec::as_slice).collect_vec(),
-    );
+        Ok(content)
+    })?;
+    let removed_contents = contents.removes().iter().map(Vec::as_slice).collect_vec();
+    let added_contents = contents.adds().iter().map(Vec::as_slice).collect_vec();
+    let merge_result = files::merge(&removed_contents, &added_contents);
     match merge_result {
         MergeResult::Resolved(merged_content) => {
             let id = store.write_file(filename, &mut merged_content.0.as_slice())?;