1 files changed, 93 insertions, 0 deletions
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxxTuple.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxxTuple.cpp
new file mode 100644
index 0000000000000..45294e25f0f5d
--- /dev/null
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxxTuple.cpp
@@ -0,0 +1,93 @@
+//===-- LibCxxTuple.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 TupleFrontEnd: public SyntheticChildrenFrontEnd {
+public:
+  TupleFrontEnd(ValueObject &valobj) : SyntheticChildrenFrontEnd(valobj) {
+    Update();
+  }
+
+  size_t GetIndexOfChildWithName(ConstString name) override {
+    return formatters::ExtractIndexFromString(name.GetCString());
+  }
+
+  bool MightHaveChildren() override { return true; }
+  bool Update() override;
+  size_t CalculateNumChildren() override { return m_elements.size(); }
+  ValueObjectSP GetChildAtIndex(size_t idx) override;
+
+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).
+  std::vector<ValueObject*> m_elements;
+  ValueObject* m_base = nullptr;
+};
+}
+
+bool TupleFrontEnd::Update() {
+  m_elements.clear();
+  m_base = nullptr;
+
+  ValueObjectSP base_sp;
+  base_sp = m_backend.GetChildMemberWithName(ConstString("__base_"), true);
+  if (!base_sp) {
+    // Pre r304382 name of the base element.
+    base_sp = m_backend.GetChildMemberWithName(ConstString("base_"), true);
+  }
+  if (!base_sp)
+    return false;
+  m_base = base_sp.get();
+  m_elements.assign(base_sp->GetCompilerType().GetNumDirectBaseClasses(),
+                    nullptr);
+  return false;
+}
+
+ValueObjectSP TupleFrontEnd::GetChildAtIndex(size_t idx) {
+  if (idx >= m_elements.size())
+    return ValueObjectSP();
+  if (!m_base)
+    return ValueObjectSP();
+  if (m_elements[idx])
+    return m_elements[idx]->GetSP();
+
+  CompilerType holder_type =
+      m_base->GetCompilerType().GetDirectBaseClassAtIndex(idx, nullptr);
+  if (!holder_type)
+    return ValueObjectSP();
+  ValueObjectSP holder_sp = m_base->GetChildAtIndex(idx, true);
+  if (!holder_sp)
+    return ValueObjectSP();
+
+  ValueObjectSP elem_sp = holder_sp->GetChildAtIndex(0, true);
+  if (elem_sp)
+    m_elements[idx] =
+        elem_sp->Clone(ConstString(llvm::formatv("[{0}]", idx).str())).get();
+
+  if (m_elements[idx])
+    return m_elements[idx]->GetSP();
+  return ValueObjectSP();
+}
+
+SyntheticChildrenFrontEnd *
+formatters::LibcxxTupleFrontEndCreator(CXXSyntheticChildren *,
+                                       lldb::ValueObjectSP valobj_sp) {
+  if (valobj_sp)
+    return new TupleFrontEnd(*valobj_sp);
+  return nullptr;
+}