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

//===-- LibCxxInitializerList.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 LibcxxInitializerListSyntheticFrontEnd : public SyntheticChildrenFrontEnd
        {
        public:
            LibcxxInitializerListSyntheticFrontEnd (lldb::ValueObjectSP valobj_sp);

            ~LibcxxInitializerListSyntheticFrontEnd() 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;
            CompilerType m_element_type;
            uint32_t m_element_size;
            size_t m_num_elements;
            std::map<size_t,lldb::ValueObjectSP> m_children;
        };
    } // namespace formatters
} // namespace lldb_private

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

lldb_private::formatters::LibcxxInitializerListSyntheticFrontEnd::~LibcxxInitializerListSyntheticFrontEnd()
{
    // this needs to stay around because it's a child object who will follow its parent's life cycle
    // delete m_start;
}

size_t
lldb_private::formatters::LibcxxInitializerListSyntheticFrontEnd::CalculateNumChildren ()
{
    static ConstString g___size_("__size_");
    m_num_elements = 0;
    ValueObjectSP size_sp(m_backend.GetChildMemberWithName(g___size_, true));
    if (size_sp)
        m_num_elements = size_sp->GetValueAsUnsigned(0);
    return m_num_elements;
}

lldb::ValueObjectSP
lldb_private::formatters::LibcxxInitializerListSyntheticFrontEnd::GetChildAtIndex (size_t idx)
{
    if (!m_start)
        return lldb::ValueObjectSP();
    
    auto cached = m_children.find(idx);
    if (cached != m_children.end())
        return cached->second;
    
    uint64_t offset = idx * m_element_size;
    offset = offset + m_start->GetValueAsUnsigned(0);
    StreamString name;
    name.Printf("[%" PRIu64 "]", (uint64_t)idx);
    ValueObjectSP child_sp = CreateValueObjectFromAddress(name.GetData(), offset, m_backend.GetExecutionContextRef(), m_element_type);
    m_children[idx] = child_sp;
    return child_sp;
}

bool
lldb_private::formatters::LibcxxInitializerListSyntheticFrontEnd::Update()
{
    static ConstString g___begin_("__begin_");

    m_start = nullptr;
    m_num_elements = 0;
    m_children.clear();
    lldb::TemplateArgumentKind kind;
    m_element_type = m_backend.GetCompilerType().GetTemplateArgument(0, kind);
    if (kind != lldb::eTemplateArgumentKindType || !m_element_type.IsValid())
        return false;
    
    m_element_size = m_element_type.GetByteSize(nullptr);
    
    if (m_element_size > 0)
        m_start = m_backend.GetChildMemberWithName(g___begin_,true).get(); // store raw pointers or end up with a circular dependency

    return false;
}

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

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

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