LibCxxTuple.cpp revision 360784 
1//===-- LibCxxTuple.cpp -----------------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "LibCxx.h"
10#include "lldb/DataFormatters/FormattersHelpers.h"
11
12using namespace lldb;
13using namespace lldb_private;
14
15namespace {
16
17class TupleFrontEnd: public SyntheticChildrenFrontEnd {
18public:
19  TupleFrontEnd(ValueObject &valobj) : SyntheticChildrenFrontEnd(valobj) {
20    Update();
21  }
22
23  size_t GetIndexOfChildWithName(ConstString name) override {
24    return formatters::ExtractIndexFromString(name.GetCString());
25  }
26
27  bool MightHaveChildren() override { return true; }
28  bool Update() override;
29  size_t CalculateNumChildren() override { return m_elements.size(); }
30  ValueObjectSP GetChildAtIndex(size_t idx) override;
31
32private:
33  // The lifetime of a ValueObject and all its derivative ValueObjects
34  // (children, clones, etc.) is managed by a ClusterManager. These
35  // objects are only destroyed when every shared pointer to any of them
36  // is destroyed, so we must not store a shared pointer to any ValueObject
37  // derived from our backend ValueObject (since we're in the same cluster).
38  std::vector<ValueObject*> m_elements;
39  ValueObject* m_base = nullptr;
40};
41}
42
43bool TupleFrontEnd::Update() {
44  m_elements.clear();
45  m_base = nullptr;
46
47  ValueObjectSP base_sp;
48  base_sp = m_backend.GetChildMemberWithName(ConstString("__base_"), true);
49  if (!base_sp) {
50    // Pre r304382 name of the base element.
51    base_sp = m_backend.GetChildMemberWithName(ConstString("base_"), true);
52  }
53  if (!base_sp)
54    return false;
55  m_base = base_sp.get();
56  m_elements.assign(base_sp->GetCompilerType().GetNumDirectBaseClasses(),
57                    nullptr);
58  return false;
59}
60
61ValueObjectSP TupleFrontEnd::GetChildAtIndex(size_t idx) {
62  if (idx >= m_elements.size())
63    return ValueObjectSP();
64  if (!m_base)
65    return ValueObjectSP();
66  if (m_elements[idx])
67    return m_elements[idx]->GetSP();
68
69  CompilerType holder_type =
70      m_base->GetCompilerType().GetDirectBaseClassAtIndex(idx, nullptr);
71  if (!holder_type)
72    return ValueObjectSP();
73  ValueObjectSP holder_sp = m_base->GetChildAtIndex(idx, true);
74  if (!holder_sp)
75    return ValueObjectSP();
76
77  ValueObjectSP elem_sp = holder_sp->GetChildAtIndex(0, true);
78  if (elem_sp)
79    m_elements[idx] =
80        elem_sp->Clone(ConstString(llvm::formatv("[{0}]", idx).str())).get();
81
82  if (m_elements[idx])
83    return m_elements[idx]->GetSP();
84  return ValueObjectSP();
85}
86
87SyntheticChildrenFrontEnd *
88formatters::LibcxxTupleFrontEndCreator(CXXSyntheticChildren *,
89                                       lldb::ValueObjectSP valobj_sp) {
90  if (valobj_sp)
91    return new TupleFrontEnd(*valobj_sp);
92  return nullptr;
93}
94