LibStdcppTuple.cpp revision 360784 
1//===-- LibStdcppTuple.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 "LibStdcpp.h"
10
11#include "lldb/Core/ValueObject.h"
12#include "lldb/DataFormatters/FormattersHelpers.h"
13#include "lldb/DataFormatters/TypeSynthetic.h"
14#include "lldb/Utility/ConstString.h"
15
16#include <memory>
17#include <vector>
18
19using namespace lldb;
20using namespace lldb_private;
21using namespace lldb_private::formatters;
22
23namespace {
24
25class LibStdcppTupleSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
26public:
27  explicit LibStdcppTupleSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp);
28
29  size_t CalculateNumChildren() override;
30
31  lldb::ValueObjectSP GetChildAtIndex(size_t idx) override;
32
33  bool Update() override;
34
35  bool MightHaveChildren() override;
36
37  size_t GetIndexOfChildWithName(ConstString name) override;
38
39private:
40  // The lifetime of a ValueObject and all its derivative ValueObjects
41  // (children, clones, etc.) is managed by a ClusterManager. These
42  // objects are only destroyed when every shared pointer to any of them
43  // is destroyed, so we must not store a shared pointer to any ValueObject
44  // derived from our backend ValueObject (since we're in the same cluster).
45  std::vector<ValueObject*> m_members;
46};
47
48} // end of anonymous namespace
49
50LibStdcppTupleSyntheticFrontEnd::LibStdcppTupleSyntheticFrontEnd(
51    lldb::ValueObjectSP valobj_sp)
52    : SyntheticChildrenFrontEnd(*valobj_sp) {
53  Update();
54}
55
56bool LibStdcppTupleSyntheticFrontEnd::Update() {
57  m_members.clear();
58
59  ValueObjectSP valobj_backend_sp = m_backend.GetSP();
60  if (!valobj_backend_sp)
61    return false;
62
63  ValueObjectSP next_child_sp = valobj_backend_sp->GetNonSyntheticValue();
64  while (next_child_sp != nullptr) {
65    ValueObjectSP current_child = next_child_sp;
66    next_child_sp = nullptr;
67
68    size_t child_count = current_child->GetNumChildren();
69    for (size_t i = 0; i < child_count; ++i) {
70      ValueObjectSP child_sp = current_child->GetChildAtIndex(i, true);
71      llvm::StringRef name_str = child_sp->GetName().GetStringRef();
72      if (name_str.startswith("std::_Tuple_impl<")) {
73        next_child_sp = child_sp;
74      } else if (name_str.startswith("std::_Head_base<")) {
75        ValueObjectSP value_sp =
76            child_sp->GetChildMemberWithName(ConstString("_M_head_impl"), true);
77        if (value_sp) {
78          StreamString name;
79          name.Printf("[%zd]", m_members.size());
80          m_members.push_back(value_sp->Clone(ConstString(name.GetString())).get());
81        }
82      }
83    }
84  }
85
86  return false;
87}
88
89bool LibStdcppTupleSyntheticFrontEnd::MightHaveChildren() { return true; }
90
91lldb::ValueObjectSP
92LibStdcppTupleSyntheticFrontEnd::GetChildAtIndex(size_t idx) {
93  if (idx < m_members.size() && m_members[idx])
94    return m_members[idx]->GetSP();
95  return lldb::ValueObjectSP();
96}
97
98size_t LibStdcppTupleSyntheticFrontEnd::CalculateNumChildren() {
99  return m_members.size();
100}
101
102size_t LibStdcppTupleSyntheticFrontEnd::GetIndexOfChildWithName(
103    ConstString name) {
104  return ExtractIndexFromString(name.GetCString());
105}
106
107SyntheticChildrenFrontEnd *
108lldb_private::formatters::LibStdcppTupleSyntheticFrontEndCreator(
109    CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
110  return (valobj_sp ? new LibStdcppTupleSyntheticFrontEnd(valobj_sp) : nullptr);
111}
112