1 files changed, 107 insertions, 0 deletions
diff --git a/source/Plugins/Language/CPlusPlus/LibCxxBitset.cpp b/source/Plugins/Language/CPlusPlus/LibCxxBitset.cpp
new file mode 100644
index 000000000000..0cdb0b26cf3b
--- /dev/null
+++ b/source/Plugins/Language/CPlusPlus/LibCxxBitset.cpp
@@ -0,0 +1,107 @@
+//===-- LibCxxBitset.cpp ----------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "LibCxx.h"
+#include "lldb/DataFormatters/FormattersHelpers.h"
+#include "lldb/Symbol/ClangASTContext.h"
+#include "lldb/Target/Target.h"
+
+using namespace lldb;
+using namespace lldb_private;
+
+namespace {
+
+class BitsetFrontEnd : public SyntheticChildrenFrontEnd {
+public:
+  BitsetFrontEnd(ValueObject &valobj);
+
+  size_t GetIndexOfChildWithName(const 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:
+  std::vector<ValueObjectSP> m_elements;
+  ValueObjectSP m_first;
+  CompilerType m_bool_type;
+  ByteOrder m_byte_order = eByteOrderInvalid;
+  uint8_t m_byte_size = 0;
+};
+} // namespace
+
+BitsetFrontEnd::BitsetFrontEnd(ValueObject &valobj)
+    : SyntheticChildrenFrontEnd(valobj) {
+  m_bool_type = valobj.GetCompilerType().GetBasicTypeFromAST(eBasicTypeBool);
+  if (auto target_sp = m_backend.GetTargetSP()) {
+    m_byte_order = target_sp->GetArchitecture().GetByteOrder();
+    m_byte_size = target_sp->GetArchitecture().GetAddressByteSize();
+    Update();
+  }
+}
+
+bool BitsetFrontEnd::Update() {
+  m_elements.clear();
+  m_first.reset();
+
+  TargetSP target_sp = m_backend.GetTargetSP();
+  if (!target_sp)
+    return false;
+  size_t capping_size = target_sp->GetMaximumNumberOfChildrenToDisplay();
+
+  size_t size = 0;
+  if (auto arg = m_backend.GetCompilerType().GetIntegralTemplateArgument(0))
+    size = arg->value.getLimitedValue(capping_size);
+
+  m_elements.assign(size, ValueObjectSP());
+
+  m_first = m_backend.GetChildMemberWithName(ConstString("__first_"), true);
+  return false;
+}
+
+ValueObjectSP BitsetFrontEnd::GetChildAtIndex(size_t idx) {
+  if (idx >= m_elements.size() || !m_first)
+    return ValueObjectSP();
+
+  if (m_elements[idx])
+    return m_elements[idx];
+
+  ExecutionContext ctx = m_backend.GetExecutionContextRef().Lock(false);
+  CompilerType type;
+  ValueObjectSP chunk;
+  // For small bitsets __first_ is not an array, but a plain size_t.
+  if (m_first->GetCompilerType().IsArrayType(&type, nullptr, nullptr))
+    chunk = m_first->GetChildAtIndex(
+        idx / type.GetBitSize(ctx.GetBestExecutionContextScope()), true);
+  else {
+    type = m_first->GetCompilerType();
+    chunk = m_first;
+  }
+  if (!type || !chunk)
+    return ValueObjectSP();
+
+  size_t chunk_idx = idx % type.GetBitSize(ctx.GetBestExecutionContextScope());
+  uint8_t value = !!(chunk->GetValueAsUnsigned(0) & (uint64_t(1) << chunk_idx));
+  DataExtractor data(&value, sizeof(value), m_byte_order, m_byte_size);
+
+  m_elements[idx] = CreateValueObjectFromData(llvm::formatv("[{0}]", idx).str(),
+                                              data, ctx, m_bool_type);
+
+  return m_elements[idx];
+}
+
+SyntheticChildrenFrontEnd *formatters::LibcxxBitsetSyntheticFrontEndCreator(
+    CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
+  if (valobj_sp)
+    return new BitsetFrontEnd(*valobj_sp);
+  return nullptr;
+}