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

   1 //===-- LibCxxQueue.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 QueueFrontEnd : public SyntheticChildrenFrontEnd {
  18 public:
  19   QueueFrontEnd(ValueObject &valobj) : SyntheticChildrenFrontEnd(valobj) {
  20     Update();
  21   }
  22
  23   size_t GetIndexOfChildWithName(ConstString name) override {
  24     return m_container_sp ? m_container_sp->GetIndexOfChildWithName(name)
  25                           : UINT32_MAX;
  26   }
  27
  28   bool MightHaveChildren() override { return true; }
  29   lldb::ChildCacheState Update() override;
  30
  31   llvm::Expected<uint32_t> CalculateNumChildren() override {
  32     return m_container_sp ? m_container_sp->GetNumChildren() : 0;
  33   }
  34
  35   ValueObjectSP GetChildAtIndex(uint32_t idx) override {
  36     return m_container_sp ? m_container_sp->GetChildAtIndex(idx)
  37                           : nullptr;
  38   }
  39
  40 private:
  41   // The lifetime of a ValueObject and all its derivative ValueObjects
  42   // (children, clones, etc.) is managed by a ClusterManager. These
  43   // objects are only destroyed when every shared pointer to any of them
  44   // is destroyed, so we must not store a shared pointer to any ValueObject
  45   // derived from our backend ValueObject (since we're in the same cluster).
  46   ValueObject* m_container_sp = nullptr;
  47 };
  48 } // namespace
  49
  50 lldb::ChildCacheState QueueFrontEnd::Update() {
  51   m_container_sp = nullptr;
  52   ValueObjectSP c_sp = m_backend.GetChildMemberWithName("c");
  53   if (!c_sp)
  54     return lldb::ChildCacheState::eRefetch;
  55   m_container_sp = c_sp->GetSyntheticValue().get();
  56   return lldb::ChildCacheState::eRefetch;
  57 }
  58
  59 SyntheticChildrenFrontEnd *
  60 formatters::LibcxxQueueFrontEndCreator(CXXSyntheticChildren *,
  61                                        lldb::ValueObjectSP valobj_sp) {
  62   if (valobj_sp)
  63     return new QueueFrontEnd(*valobj_sp);
  64   return nullptr;
  65 }