HRESULT STDMETHODCALLTYPE CCppCustomVisualizerService::UseDefaultEvaluationBehavior()

in CppCustomVisualizer/dll/_EntryPoint.cpp [137:241]
84 lines of code
6 McCabe index (conditional complexity)

HRESULT STDMETHODCALLTYPE CCppCustomVisualizerService::UseDefaultEvaluationBehavior(
    _In_ Evaluation::DkmVisualizedExpression* pVisualizedExpression,
    _Out_ bool* pUseDefaultEvaluationBehavior,
    _Deref_out_opt_ Evaluation::DkmEvaluationResult** ppDefaultEvaluationResult
    )
{
    HRESULT hr;

    // This method is called by the expression evaluator when a visualized expression's children are
    // being expanded, or the value is being set. We just want to delegate this back to the C++ EE.
    // So we need to set `*pUseDefaultEvaluationBehavior` to true and return the evaluation result which would
    // be created if this custom visualizer didn't exist.
    //
    // NOTE: If this custom visualizer supported underlying strings (no DkmEvaluationResultFlags::RawString),
    // this method would also be called when that is requested.

    DkmRootVisualizedExpression* pRootVisualizedExpression = DkmRootVisualizedExpression::TryCast(pVisualizedExpression);
    if (pRootVisualizedExpression == nullptr)
    {
        // This sample doesn't provide child evaluation results, so only root expressions are expected
        return E_NOTIMPL;
    }

    DkmInspectionContext* pParentInspectionContext = pVisualizedExpression->InspectionContext();

    CAutoDkmClosePtr<DkmLanguageExpression> pLanguageExpression;
    hr = DkmLanguageExpression::Create(
        pParentInspectionContext->Language(),
        DkmEvaluationFlags::TreatAsExpression,
        pRootVisualizedExpression->FullName(),
        DkmDataItem::Null(),
        &pLanguageExpression
        );
    if (FAILED(hr))
    {
        return hr;
    }

    // Create a new inspection context with 'DkmEvaluationFlags::ShowValueRaw' set. This is important because
    // the result of the expression is a FILETIME, and we don't want our visualizer to be invoked again. This
    // step would be unnecessary if we were evaluating a different expression that resulted in a type which
    // we didn't visualize.
    CComPtr<DkmInspectionContext> pInspectionContext;
    if (DkmComponentManager::IsApiVersionSupported(DkmApiVersion::VS16RTMPreview))
    {
        // If we are running in VS 16 or newer, use this overload...
        hr = DkmInspectionContext::Create(
            pParentInspectionContext->InspectionSession(),
            pParentInspectionContext->RuntimeInstance(),
            pParentInspectionContext->Thread(),
            pParentInspectionContext->Timeout(),
            DkmEvaluationFlags::TreatAsExpression |
            DkmEvaluationFlags::ShowValueRaw,
            pParentInspectionContext->FuncEvalFlags(),
            pParentInspectionContext->Radix(),
            pParentInspectionContext->Language(),
            pParentInspectionContext->ReturnValue(),
            (Evaluation::DkmCompiledVisualizationData*)nullptr,
            Evaluation::DkmCompiledVisualizationDataPriority::None,
            pParentInspectionContext->ReturnValues(),
            pParentInspectionContext->SymbolsConnection(),
            &pInspectionContext
            );
    }
    else
    {
        // Otherwise fall back to the Visual Studio 14 version
        hr = DkmInspectionContext::Create(
            pParentInspectionContext->InspectionSession(),
            pParentInspectionContext->RuntimeInstance(),
            pParentInspectionContext->Thread(),
            pParentInspectionContext->Timeout(),
            DkmEvaluationFlags::TreatAsExpression |
            DkmEvaluationFlags::ShowValueRaw,
            pParentInspectionContext->FuncEvalFlags(),
            pParentInspectionContext->Radix(),
            pParentInspectionContext->Language(),
            pParentInspectionContext->ReturnValue(),
            (Evaluation::DkmCompiledVisualizationData*)nullptr,
            Evaluation::DkmCompiledVisualizationDataPriority::None,
            pParentInspectionContext->ReturnValues(),
            &pInspectionContext
            );
    }
    if (FAILED(hr))
    {
        return hr;
    }

    CComPtr<DkmEvaluationResult> pEEEvaluationResult;
    hr = pVisualizedExpression->EvaluateExpressionCallback(
        pInspectionContext,
        pLanguageExpression,
        pVisualizedExpression->StackFrame(),
        &pEEEvaluationResult
        );
    if (FAILED(hr))
    {
        return hr;
    }

    *ppDefaultEvaluationResult = pEEEvaluationResult.Detach();
    *pUseDefaultEvaluationBehavior = true;
    return S_OK;
}