llvm-project/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp

//===-- LibCxxVector.cpp ----------------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// C Includes
// C++ Includes
// Other libraries and framework includes
// Project includes
#include "LibCxx.h"

#include "lldb/Core/ConstString.h"
#include "lldb/Core/ValueObject.h"
#include "lldb/DataFormatters/FormattersHelpers.h"

using namespace lldb;
using namespace lldb_private;
using namespace lldb_private::formatters;

namespace lldb_private {
namespace formatters {
class LibcxxStdVectorSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
public:
  LibcxxStdVectorSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp);

  ~LibcxxStdVectorSyntheticFrontEnd() override;

  size_t CalculateNumChildren() override;

  lldb::ValueObjectSP GetChildAtIndex(size_t idx) override;

  bool Update() override;

  bool MightHaveChildren() override;

  size_t GetIndexOfChildWithName(const ConstString &name) override;

private:
  ValueObject *m_start;
  ValueObject *m_finish;
  CompilerType m_element_type;
  uint32_t m_element_size;
};
} // namespace formatters
} // namespace lldb_private

lldb_private::formatters::LibcxxStdVectorSyntheticFrontEnd::
    LibcxxStdVectorSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
    : SyntheticChildrenFrontEnd(*valobj_sp), m_start(nullptr),
      m_finish(nullptr), m_element_type(), m_element_size(0) {
  if (valobj_sp)
    Update();
}

lldb_private::formatters::LibcxxStdVectorSyntheticFrontEnd::
    ~LibcxxStdVectorSyntheticFrontEnd() {
  // these need to stay around because they are child objects who will follow
  // their parent's life cycle
  // delete m_start;
  // delete m_finish;
}

size_t lldb_private::formatters::LibcxxStdVectorSyntheticFrontEnd::
    CalculateNumChildren() {
  if (!m_start || !m_finish)
    return 0;
  uint64_t start_val = m_start->GetValueAsUnsigned(0);
  uint64_t finish_val = m_finish->GetValueAsUnsigned(0);

  if (start_val == 0 || finish_val == 0)
    return 0;

  if (start_val >= finish_val)
    return 0;

  size_t num_children = (finish_val - start_val);
  if (num_children % m_element_size)
    return 0;
  return num_children / m_element_size;
}

lldb::ValueObjectSP
lldb_private::formatters::LibcxxStdVectorSyntheticFrontEnd::GetChildAtIndex(
    size_t idx) {
  if (!m_start || !m_finish)
    return lldb::ValueObjectSP();

  uint64_t offset = idx * m_element_size;
  offset = offset + m_start->GetValueAsUnsigned(0);
  StreamString name;
  name.Printf("[%" PRIu64 "]", (uint64_t)idx);
  return CreateValueObjectFromAddress(name.GetString(), offset,
                                      m_backend.GetExecutionContextRef(),
                                      m_element_type);
}

bool lldb_private::formatters::LibcxxStdVectorSyntheticFrontEnd::Update() {
  m_start = m_finish = nullptr;
  ValueObjectSP data_type_finder_sp(
      m_backend.GetChildMemberWithName(ConstString("__end_cap_"), true));
  if (!data_type_finder_sp)
    return false;
  data_type_finder_sp = data_type_finder_sp->GetChildMemberWithName(
      ConstString("__first_"), true);
  if (!data_type_finder_sp)
    return false;
  m_element_type = data_type_finder_sp->GetCompilerType().GetPointeeType();
  m_element_size = m_element_type.GetByteSize(nullptr);

  if (m_element_size > 0) {
    // store raw pointers or end up with a circular dependency
    m_start =
        m_backend.GetChildMemberWithName(ConstString("__begin_"), true).get();
    m_finish =
        m_backend.GetChildMemberWithName(ConstString("__end_"), true).get();
  }
  return false;
}

bool lldb_private::formatters::LibcxxStdVectorSyntheticFrontEnd::
    MightHaveChildren() {
  return true;
}

size_t lldb_private::formatters::LibcxxStdVectorSyntheticFrontEnd::
    GetIndexOfChildWithName(const ConstString &name) {
  if (!m_start || !m_finish)
    return UINT32_MAX;
  return ExtractIndexFromString(name.GetCString());
}

lldb_private::SyntheticChildrenFrontEnd *
lldb_private::formatters::LibcxxStdVectorSyntheticFrontEndCreator(
    CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
  return (valobj_sp ? new LibcxxStdVectorSyntheticFrontEnd(valobj_sp)
                    : nullptr);
}