From 95f8f3d45fe077042df4fd4afa73d4e419bc9974 Mon Sep 17 00:00:00 2001
From: Runxi Yu
Date: Fri, 6 Mar 2026 10:59:53 +0800
Subject: reachability: Split walk files

---
 reachability/walk_expand_commits.go | 70 +++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 reachability/walk_expand_commits.go

(limited to 'reachability/walk_expand_commits.go')

diff --git a/reachability/walk_expand_commits.go b/reachability/walk_expand_commits.go
new file mode 100644
index 00000000..11c5c692
--- /dev/null
+++ b/reachability/walk_expand_commits.go
@@ -0,0 +1,70 @@
+package reachability
+
+import (
+	"fmt"
+
+	"codeberg.org/lindenii/furgit/object"
+	"codeberg.org/lindenii/furgit/objecttype"
+)
+
+func (walk *Walk) expandCommits(item walkItem) ([]walkItem, error) {
+	if walk.reachability.graph != nil { //nolint:nestif
+		next, graphUsed, err := walk.expandCommitsFromGraph(item.id)
+		if err != nil {
+			return nil, err
+		}
+
+		if graphUsed && walk.strict {
+			err = walk.validateCommitObject(item.id)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		if graphUsed {
+			return next, nil
+		}
+	}
+
+	ty, err := walk.readHeaderType(item.id)
+	if err != nil {
+		return nil, err
+	}
+
+	switch ty {
+	case objecttype.TypeCommit:
+		content, err := walk.readBytesContent(item.id)
+		if err != nil {
+			return nil, err
+		}
+
+		commit, err := object.ParseCommit(content, item.id.Algorithm())
+		if err != nil {
+			return nil, err
+		}
+
+		next := make([]walkItem, 0, len(commit.Parents))
+		for _, parent := range commit.Parents {
+			next = append(next, walkItem{id: parent, want: objecttype.TypeInvalid})
+		}
+
+		return next, nil
+	case objecttype.TypeTag:
+		content, err := walk.readBytesContent(item.id)
+		if err != nil {
+			return nil, err
+		}
+
+		tag, err := object.ParseTag(content, item.id.Algorithm())
+		if err != nil {
+			return nil, err
+		}
+
+		return []walkItem{{id: tag.Target, want: objecttype.TypeInvalid}}, nil
+	case objecttype.TypeTree, objecttype.TypeBlob, objecttype.TypeInvalid,
+		objecttype.TypeFuture, objecttype.TypeOfsDelta, objecttype.TypeRefDelta:
+		return nil, &ErrObjectType{OID: item.id, Got: ty, Want: objecttype.TypeCommit}
+	}
+
+	return nil, fmt.Errorf("reachability: unreachable object type %d", ty)
+}
-- 
cgit v1.3.1-10-gc9f91