1 files changed, 65 insertions, 0 deletions
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxxQueue.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxxQueue.cpp
new file mode 100644
index 000000000000..2f06d684f953
--- /dev/null
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxxQueue.cpp
@@ -0,0 +1,65 @@
+//===-- LibCxxQueue.cpp -----------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "LibCxx.h"
+#include "lldb/DataFormatters/FormattersHelpers.h"
+
+using namespace lldb;
+using namespace lldb_private;
+
+namespace {
+
+class QueueFrontEnd : public SyntheticChildrenFrontEnd {
+public:
+  QueueFrontEnd(ValueObject &valobj) : SyntheticChildrenFrontEnd(valobj) {
+    Update();
+  }
+
+  size_t GetIndexOfChildWithName(ConstString name) override {
+    return m_container_sp ? m_container_sp->GetIndexOfChildWithName(name)
+                          : UINT32_MAX;
+  }
+
+  bool MightHaveChildren() override { return true; }
+  bool Update() override;
+
+  size_t CalculateNumChildren() override {
+    return m_container_sp ? m_container_sp->GetNumChildren() : 0;
+  }
+
+  ValueObjectSP GetChildAtIndex(size_t idx) override {
+    return m_container_sp ? m_container_sp->GetChildAtIndex(idx, true)
+                          : nullptr;
+  }
+
+private:
+  // The lifetime of a ValueObject and all its derivative ValueObjects
+  // (children, clones, etc.) is managed by a ClusterManager. These
+  // objects are only destroyed when every shared pointer to any of them
+  // is destroyed, so we must not store a shared pointer to any ValueObject
+  // derived from our backend ValueObject (since we're in the same cluster).
+  ValueObject* m_container_sp = nullptr;
+};
+} // namespace
+
+bool QueueFrontEnd::Update() {
+  m_container_sp = nullptr;
+  ValueObjectSP c_sp = m_backend.GetChildMemberWithName(ConstString("c"), true);
+  if (!c_sp)
+    return false;
+  m_container_sp = c_sp->GetSyntheticValue().get();
+  return false;
+}
+
+SyntheticChildrenFrontEnd *
+formatters::LibcxxQueueFrontEndCreator(CXXSyntheticChildren *,
+                                       lldb::ValueObjectSP valobj_sp) {
+  if (valobj_sp)
+    return new QueueFrontEnd(*valobj_sp);
+  return nullptr;
+}