lldb/source/Plugins/Language/CPlusPlus/LibCxxTuple.cpp

   1 //===-- LibCxxTuple.cpp ---------------------------------------------------===//
   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
  12 using namespace lldb;
  13 using namespace lldb_private;
  14
  15 namespace {
  16
  17 class TupleFrontEnd: public SyntheticChildrenFrontEnd {
  18 public:
  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   lldb::ChildCacheState Update() override;
  29   llvm::Expected<uint32_t> CalculateNumChildren() override {
  30     return m_elements.size();
  31   }
  32   ValueObjectSP GetChildAtIndex(uint32_t idx) override;
  33
  34 private:
  35   // The lifetime of a ValueObject and all its derivative ValueObjects
  36   // (children, clones, etc.) is managed by a ClusterManager. These
  37   // objects are only destroyed when every shared pointer to any of them
  38   // is destroyed, so we must not store a shared pointer to any ValueObject
  39   // derived from our backend ValueObject (since we're in the same cluster).
  40   std::vector<ValueObject*> m_elements;
  41   ValueObject* m_base = nullptr;
  42 };
  43 }
  44
  45 lldb::ChildCacheState TupleFrontEnd::Update() {
  46   m_elements.clear();
  47   m_base = nullptr;
  48
  49   ValueObjectSP base_sp;
  50   base_sp = m_backend.GetChildMemberWithName("__base_");
  51   if (!base_sp) {
  52     // Pre r304382 name of the base element.
  53     base_sp = m_backend.GetChildMemberWithName("base_");
  54   }
  55   if (!base_sp)
  56     return lldb::ChildCacheState::eRefetch;
  57   m_base = base_sp.get();
  58   m_elements.assign(base_sp->GetCompilerType().GetNumDirectBaseClasses(),
  59                     nullptr);
  60   return lldb::ChildCacheState::eRefetch;
  61 }
  62
  63 ValueObjectSP TupleFrontEnd::GetChildAtIndex(uint32_t idx) {
  64   if (idx >= m_elements.size())
  65     return ValueObjectSP();
  66   if (!m_base)
  67     return ValueObjectSP();
  68   if (m_elements[idx])
  69     return m_elements[idx]->GetSP();
  70
  71   CompilerType holder_type =
  72       m_base->GetCompilerType().GetDirectBaseClassAtIndex(idx, nullptr);
  73   if (!holder_type)
  74     return ValueObjectSP();
  75   ValueObjectSP holder_sp = m_base->GetChildAtIndex(idx);
  76   if (!holder_sp)
  77     return ValueObjectSP();
  78
  79   ValueObjectSP elem_sp = holder_sp->GetChildAtIndex(0);
  80   if (elem_sp)
  81     m_elements[idx] =
  82         elem_sp->Clone(ConstString(llvm::formatv("[{0}]", idx).str())).get();
  83
  84   if (m_elements[idx])
  85     return m_elements[idx]->GetSP();
  86   return ValueObjectSP();
  87 }
  88
  89 SyntheticChildrenFrontEnd *
  90 formatters::LibcxxTupleFrontEndCreator(CXXSyntheticChildren *,
  91                                        lldb::ValueObjectSP valobj_sp) {
  92   if (valobj_sp)
  93     return new TupleFrontEnd(*valobj_sp);
  94   return nullptr;
  95 }