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//===-- LibCxxOptional.cpp ------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "LibCxx.h"
#include "lldb/DataFormatters/FormattersHelpers.h"
using namespace lldb;
using namespace lldb_private;
namespace {
class OptionalFrontEnd : public SyntheticChildrenFrontEnd {
public:
OptionalFrontEnd(ValueObject &valobj) : SyntheticChildrenFrontEnd(valobj) {
Update();
}
size_t GetIndexOfChildWithName(ConstString name) override {
return formatters::ExtractIndexFromString(name.GetCString());
}
bool MightHaveChildren() override { return true; }
bool Update() override;
size_t CalculateNumChildren() override { return m_has_value ? 1U : 0U; }
ValueObjectSP GetChildAtIndex(size_t idx) override;
private:
/// True iff the option contains a value.
bool m_has_value = false;
};
} // namespace
bool OptionalFrontEnd::Update() {
ValueObjectSP engaged_sp(
m_backend.GetChildMemberWithName(ConstString("__engaged_"), true));
if (!engaged_sp)
return false;
// __engaged_ is a bool flag and is true if the optional contains a value.
// Converting it to unsigned gives us a size of 1 if it contains a value
// and 0 if not.
m_has_value = engaged_sp->GetValueAsUnsigned(0) == 1;
return false;
}
ValueObjectSP OptionalFrontEnd::GetChildAtIndex(size_t idx) {
if (!m_has_value)
return ValueObjectSP();
// __val_ contains the underlying value of an optional if it has one.
// Currently because it is part of an anonymous union GetChildMemberWithName()
// does not peer through and find it unless we are at the parent itself.
// We can obtain the parent through __engaged_.
ValueObjectSP val_sp(
m_backend.GetChildMemberWithName(ConstString("__engaged_"), true)
->GetParent()
->GetChildAtIndex(0, true)
->GetChildMemberWithName(ConstString("__val_"), true));
if (!val_sp)
return ValueObjectSP();
CompilerType holder_type = val_sp->GetCompilerType();
if (!holder_type)
return ValueObjectSP();
return val_sp->Clone(ConstString("Value"));
}
SyntheticChildrenFrontEnd *
formatters::LibcxxOptionalFrontEndCreator(CXXSyntheticChildren *,
lldb::ValueObjectSP valobj_sp) {
if (valobj_sp)
return new OptionalFrontEnd(*valobj_sp);
return nullptr;
}
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