xref: /llvm-project-15.0.7/lldb/source/DataFormatters/ValueObjectPrinter.cpp (revision 520a422b)

//===-- ValueObjectPrinter.cpp -------------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "lldb/DataFormatters/ValueObjectPrinter.h"

// C Includes
// C++ Includes
// Other libraries and framework includes
// Project includes
#include "lldb/Core/Stream.h"
#include "lldb/Core/ValueObject.h"
#include "lldb/DataFormatters/DataVisualization.h"
#include "lldb/Interpreter/CommandInterpreter.h"
#include "lldb/Target/Language.h"
#include "lldb/Target/Target.h"

using namespace lldb;
using namespace lldb_private;

ValueObjectPrinter::ValueObjectPrinter (ValueObject* valobj,
                                        Stream* s)
{
    if (valobj)
    {
        DumpValueObjectOptions options(*valobj);
        Init (valobj,s,options,m_options.m_max_ptr_depth,0, nullptr);
    }
    else
    {
        DumpValueObjectOptions options;
        Init (valobj,s,options,m_options.m_max_ptr_depth,0, nullptr);
    }
}

ValueObjectPrinter::ValueObjectPrinter (ValueObject* valobj,
                                        Stream* s,
                                        const DumpValueObjectOptions& options)
{
    Init(valobj,s,options,m_options.m_max_ptr_depth,0, nullptr);
}

ValueObjectPrinter::ValueObjectPrinter (ValueObject* valobj,
                                        Stream* s,
                                        const DumpValueObjectOptions& options,
                                        const DumpValueObjectOptions::PointerDepth& ptr_depth,
                                        uint32_t curr_depth,
                                        InstancePointersSetSP printed_instance_pointers)
{
    Init(valobj,s,options,ptr_depth,curr_depth, printed_instance_pointers);
}

void
ValueObjectPrinter::Init (ValueObject* valobj,
                          Stream* s,
                          const DumpValueObjectOptions& options,
                          const DumpValueObjectOptions::PointerDepth& ptr_depth,
                          uint32_t curr_depth,
                          InstancePointersSetSP printed_instance_pointers)
{
    m_orig_valobj = valobj;
    m_valobj = nullptr;
    m_stream = s;
    m_options = options;
    m_ptr_depth = ptr_depth;
    m_curr_depth = curr_depth;
    assert (m_orig_valobj && "cannot print a NULL ValueObject");
    assert (m_stream && "cannot print to a NULL Stream");
    m_should_print = eLazyBoolCalculate;
    m_is_nil = eLazyBoolCalculate;
    m_is_uninit = eLazyBoolCalculate;
    m_is_ptr = eLazyBoolCalculate;
    m_is_ref = eLazyBoolCalculate;
    m_is_aggregate = eLazyBoolCalculate;
    m_is_instance_ptr = eLazyBoolCalculate;
    m_summary_formatter = {nullptr,false};
    m_value.assign("");
    m_summary.assign("");
    m_error.assign("");
    m_val_summary_ok = false;
    m_printed_instance_pointers = printed_instance_pointers ? printed_instance_pointers : InstancePointersSetSP(new InstancePointersSet());
}

bool
ValueObjectPrinter::PrintValueObject ()
{
    if (!GetMostSpecializedValue () || m_valobj == nullptr)
        return false;

    if (ShouldPrintValueObject())
    {
        PrintValidationMarkerIfNeeded();

        PrintLocationIfNeeded();
        m_stream->Indent();

        PrintDecl();
    }

    bool value_printed = false;
    bool summary_printed = false;

    m_val_summary_ok = PrintValueAndSummaryIfNeeded (value_printed,summary_printed);

    if (m_val_summary_ok)
        PrintChildrenIfNeeded (value_printed, summary_printed);
    else
        m_stream->EOL();

    PrintValidationErrorIfNeeded();

    return true;
}

bool
ValueObjectPrinter::GetMostSpecializedValue ()
{
    if (m_valobj)
        return true;
    bool update_success = m_orig_valobj->UpdateValueIfNeeded (true);
    if (!update_success)
    {
        m_valobj = m_orig_valobj;
    }
    else
    {
        if (m_orig_valobj->IsDynamic())
        {
            if (m_options.m_use_dynamic == eNoDynamicValues)
            {
                ValueObject *static_value = m_orig_valobj->GetStaticValue().get();
                if (static_value)
                    m_valobj = static_value;
                else
                    m_valobj = m_orig_valobj;
            }
            else
                m_valobj = m_orig_valobj;
        }
        else
        {
            if (m_options.m_use_dynamic != eNoDynamicValues)
            {
                ValueObject *dynamic_value = m_orig_valobj->GetDynamicValue(m_options.m_use_dynamic).get();
                if (dynamic_value)
                    m_valobj = dynamic_value;
                else
                    m_valobj = m_orig_valobj;
            }
            else
                m_valobj = m_orig_valobj;
        }

        if (m_valobj->IsSynthetic())
        {
            if (m_options.m_use_synthetic == false)
            {
                ValueObject *non_synthetic = m_valobj->GetNonSyntheticValue().get();
                if (non_synthetic)
                    m_valobj = non_synthetic;
            }
        }
        else
        {
            if (m_options.m_use_synthetic == true)
            {
                ValueObject *synthetic = m_valobj->GetSyntheticValue().get();
                if (synthetic)
                    m_valobj = synthetic;
            }
        }
    }
    m_compiler_type = m_valobj->GetCompilerType();
    m_type_flags = m_compiler_type.GetTypeInfo ();
    return true;
}

const char*
ValueObjectPrinter::GetDescriptionForDisplay ()
{
    const char* str = m_valobj->GetObjectDescription();
    if (!str)
        str = m_valobj->GetSummaryAsCString();
    if (!str)
        str = m_valobj->GetValueAsCString();
    return str;
}

const char*
ValueObjectPrinter::GetRootNameForDisplay (const char* if_fail)
{
    const char *root_valobj_name = m_options.m_root_valobj_name.empty() ?
        m_valobj->GetName().AsCString() :
        m_options.m_root_valobj_name.c_str();
    return root_valobj_name ? root_valobj_name : if_fail;
}

bool
ValueObjectPrinter::ShouldPrintValueObject ()
{
    if (m_should_print == eLazyBoolCalculate)
        m_should_print = (m_options.m_flat_output == false || m_type_flags.Test (eTypeHasValue)) ? eLazyBoolYes : eLazyBoolNo;
    return m_should_print == eLazyBoolYes;
}

bool
ValueObjectPrinter::IsNil ()
{
    if (m_is_nil == eLazyBoolCalculate)
        m_is_nil = m_valobj->IsNilReference() ? eLazyBoolYes : eLazyBoolNo;
    return m_is_nil == eLazyBoolYes;
}

bool
ValueObjectPrinter::IsUninitialized ()
{
    if (m_is_uninit == eLazyBoolCalculate)
        m_is_uninit = m_valobj->IsUninitializedReference() ? eLazyBoolYes : eLazyBoolNo;
    return m_is_uninit == eLazyBoolYes;
}

bool
ValueObjectPrinter::IsPtr ()
{
    if (m_is_ptr == eLazyBoolCalculate)
        m_is_ptr = m_type_flags.Test (eTypeIsPointer) ? eLazyBoolYes : eLazyBoolNo;
    return m_is_ptr == eLazyBoolYes;
}

bool
ValueObjectPrinter::IsRef ()
{
    if (m_is_ref == eLazyBoolCalculate)
        m_is_ref = m_type_flags.Test (eTypeIsReference) ? eLazyBoolYes : eLazyBoolNo;
    return m_is_ref == eLazyBoolYes;
}

bool
ValueObjectPrinter::IsAggregate ()
{
    if (m_is_aggregate == eLazyBoolCalculate)
        m_is_aggregate = m_type_flags.Test (eTypeHasChildren) ? eLazyBoolYes : eLazyBoolNo;
    return m_is_aggregate == eLazyBoolYes;
}

bool
ValueObjectPrinter::IsInstancePointer ()
{
    // you need to do this check on the value's clang type
    if (m_is_instance_ptr == eLazyBoolCalculate)
        m_is_instance_ptr = (m_valobj->GetValue().GetCompilerType().GetTypeInfo() & eTypeInstanceIsPointer) != 0 ? eLazyBoolYes : eLazyBoolNo;
    if ((eLazyBoolYes == m_is_instance_ptr) && m_valobj->IsBaseClass())
        m_is_instance_ptr = eLazyBoolNo;
    return m_is_instance_ptr == eLazyBoolYes;
}

bool
ValueObjectPrinter::PrintLocationIfNeeded ()
{
    if (m_options.m_show_location)
    {
        m_stream->Printf("%s: ", m_valobj->GetLocationAsCString());
        return true;
    }
    return false;
}

void
ValueObjectPrinter::PrintDecl ()
{
    bool show_type = true;
    // if we are at the root-level and been asked to hide the root's type, then hide it
    if (m_curr_depth == 0 && m_options.m_hide_root_type)
        show_type = false;
    else
        // otherwise decide according to the usual rules (asked to show types - always at the root level)
        show_type = m_options.m_show_types || (m_curr_depth == 0 && !m_options.m_flat_output);

    StreamString typeName;

    // always show the type at the root level if it is invalid
    if (show_type)
    {
        // Some ValueObjects don't have types (like registers sets). Only print
        // the type if there is one to print
        ConstString type_name;
        if (m_compiler_type.IsValid())
        {
            if (m_options.m_use_type_display_name)
                type_name = m_valobj->GetDisplayTypeName();
            else
                type_name = m_valobj->GetQualifiedTypeName();
        }
        else
        {
            // only show an invalid type name if the user explicitly triggered show_type
            if (m_options.m_show_types)
                type_name = ConstString("<invalid type>");
            else
                type_name.Clear();
        }

        if (type_name)
        {
            std::string type_name_str(type_name.GetCString());
            if (m_options.m_hide_pointer_value)
            {
                for(auto iter = type_name_str.find(" *");
                    iter != std::string::npos;
                    iter = type_name_str.find(" *"))
                {
                    type_name_str.erase(iter, 2);
                }
            }
            typeName.Printf("%s", type_name_str.c_str());
        }
    }

    StreamString varName;

    if (m_options.m_flat_output)
    {
        // If we are showing types, also qualify the C++ base classes
        const bool qualify_cxx_base_classes = show_type;
        if (!m_options.m_hide_name)
        {
            m_valobj->GetExpressionPath(varName, qualify_cxx_base_classes);
        }
    }
    else if (!m_options.m_hide_name)
    {
        const char *name_cstr = GetRootNameForDisplay("");
        varName.Printf ("%s", name_cstr);
    }

    bool decl_printed = false;
    if (!m_options.m_decl_printing_helper)
    {
        // if the user didn't give us a custom helper, pick one based upon the language, either the one that this printer is bound to, or the preferred one for the ValueObject
        lldb::LanguageType lang_type = (m_options.m_varformat_language == lldb::eLanguageTypeUnknown) ? m_valobj->GetPreferredDisplayLanguage() : m_options.m_varformat_language;
        if (Language *lang_plugin = Language::FindPlugin(lang_type))
        {
            m_options.m_decl_printing_helper = lang_plugin->GetDeclPrintingHelper();
        }
    }

    if (m_options.m_decl_printing_helper)
    {
        ConstString type_name_cstr(typeName.GetData());
        ConstString var_name_cstr(varName.GetData());

        StreamString dest_stream;
        if (m_options.m_decl_printing_helper (type_name_cstr,
                                              var_name_cstr,
                                              m_options,
                                              dest_stream))
        {
            decl_printed = true;
            m_stream->Printf("%s", dest_stream.GetData());
        }
    }

    // if the helper failed, or there is none, do a default thing
    if (!decl_printed)
    {
        if (typeName.GetSize())
            m_stream->Printf("(%s) ", typeName.GetData());
        if (varName.GetSize())
            m_stream->Printf("%s =", varName.GetData());
        else if (!m_options.m_hide_name)
            m_stream->Printf(" =");
    }
}

bool
ValueObjectPrinter::CheckScopeIfNeeded ()
{
    if (m_options.m_scope_already_checked)
        return true;
    return m_valobj->IsInScope();
}

TypeSummaryImpl*
ValueObjectPrinter::GetSummaryFormatter (bool null_if_omitted)
{
    if (m_summary_formatter.second == false)
    {
        TypeSummaryImpl* entry = m_options.m_summary_sp ? m_options.m_summary_sp.get() : m_valobj->GetSummaryFormat().get();

        if (m_options.m_omit_summary_depth > 0)
            entry = NULL;
        m_summary_formatter.first = entry;
        m_summary_formatter.second = true;
    }
    if (m_options.m_omit_summary_depth > 0 && null_if_omitted)
        return nullptr;
    return m_summary_formatter.first;
}

static bool
IsPointerValue (const CompilerType &type)
{
    Flags type_flags(type.GetTypeInfo());
    if (type_flags.AnySet(eTypeInstanceIsPointer | eTypeIsPointer))
        return type_flags.AllClear(eTypeIsBuiltIn);
    return false;
}

void
ValueObjectPrinter::GetValueSummaryError (std::string& value,
                                          std::string& summary,
                                          std::string& error)
{
    lldb::Format format = m_options.m_format;
    // if I am printing synthetized elements, apply the format to those elements only
    if (m_options.m_element_count > 0)
        m_valobj->GetValueAsCString(lldb::eFormatDefault, value);
    else if (format != eFormatDefault && format != m_valobj->GetFormat())
        m_valobj->GetValueAsCString(format, value);
    else
    {
        const char* val_cstr = m_valobj->GetValueAsCString();
        if (val_cstr)
            value.assign(val_cstr);
    }
    const char* err_cstr = m_valobj->GetError().AsCString();
    if (err_cstr)
        error.assign(err_cstr);

    if (ShouldPrintValueObject())
    {
        if (IsNil())
            summary.assign("nil");
        else if (IsUninitialized())
            summary.assign("<uninitialized>");
        else if (m_options.m_omit_summary_depth == 0)
        {
            TypeSummaryImpl* entry = GetSummaryFormatter();
            if (entry)
                m_valobj->GetSummaryAsCString(entry, summary, m_options.m_varformat_language);
            else
            {
                const char* sum_cstr = m_valobj->GetSummaryAsCString(m_options.m_varformat_language);
                if (sum_cstr)
                    summary.assign(sum_cstr);
            }
        }
    }
}

bool
ValueObjectPrinter::PrintValueAndSummaryIfNeeded (bool& value_printed,
                                                  bool& summary_printed)
{
    bool error_printed = false;
    if (ShouldPrintValueObject())
    {
        if (!CheckScopeIfNeeded())
            m_error.assign("out of scope");
        if (m_error.empty())
        {
            GetValueSummaryError(m_value, m_summary, m_error);
        }
        if (m_error.size())
        {
            // we need to support scenarios in which it is actually fine for a value to have no type
            // but - on the other hand - if we get an error *AND* have no type, we try to get out
            // gracefully, since most often that combination means "could not resolve a type"
            // and the default failure mode is quite ugly
            if (!m_compiler_type.IsValid())
            {
                m_stream->Printf(" <could not resolve type>");
                return false;
            }

            error_printed = true;
            m_stream->Printf (" <%s>\n", m_error.c_str());
        }
        else
        {
            // Make sure we have a value and make sure the summary didn't
            // specify that the value should not be printed - and do not print
            // the value if this thing is nil
            // (but show the value if the user passes a format explicitly)
            TypeSummaryImpl* entry = GetSummaryFormatter();
            if (!IsNil() && !IsUninitialized() && !m_value.empty() && (entry == NULL || (entry->DoesPrintValue(m_valobj) || m_options.m_format != eFormatDefault) || m_summary.empty()) && !m_options.m_hide_value)
            {
                if (m_options.m_hide_pointer_value && IsPointerValue(m_valobj->GetCompilerType())) {}
                else
                {
                    m_stream->Printf(" %s", m_value.c_str());
                    value_printed = true;
                }
            }

            if (m_summary.size())
            {
                m_stream->Printf(" %s", m_summary.c_str());
                summary_printed = true;
            }
        }
    }
    return !error_printed;
}

bool
ValueObjectPrinter::PrintObjectDescriptionIfNeeded (bool value_printed,
                                                    bool summary_printed)
{
    if (ShouldPrintValueObject())
    {
        // let's avoid the overly verbose no description error for a nil thing
        if (m_options.m_use_objc && !IsNil() && !IsUninitialized() && (m_options.m_element_count == 0))
        {
            if (!m_options.m_hide_value || !m_options.m_hide_name)
                m_stream->Printf(" ");
            const char *object_desc = nullptr;
            if (value_printed || summary_printed)
                object_desc = m_valobj->GetObjectDescription();
            else
                object_desc = GetDescriptionForDisplay();
            if (object_desc && *object_desc)
            {
                m_stream->Printf("%s\n", object_desc);
                return true;
            }
            else if (value_printed == false && summary_printed == false)
                return true;
            else
                return false;
        }
    }
    return true;
}

bool
DumpValueObjectOptions::PointerDepth::CanAllowExpansion (bool is_root,
                                                         TypeSummaryImpl* entry,
                                                         ValueObject *valobj,
                                                         const std::string& summary)
{
    switch (m_mode)
    {
        case Mode::Always:
            return (m_count > 0);
        case Mode::Never:
            return false;
        case Mode::Default:
            if (is_root)
                m_count = std::min<decltype(m_count)>(m_count,1);
            return m_count > 0;
        case Mode::Formatters:
            if (!entry || entry->DoesPrintChildren(valobj) || summary.empty())
                return m_count > 0;
            return false;
    }
    return false;
}

bool
DumpValueObjectOptions::PointerDepth::CanAllowExpansion () const
{
    switch (m_mode)
    {
        case Mode::Always:
        case Mode::Default:
        case Mode::Formatters:
            return (m_count > 0);
        case Mode::Never:
            return false;
    }
    return false;
}

bool
ValueObjectPrinter::ShouldPrintChildren (bool is_failed_description,
                                         DumpValueObjectOptions::PointerDepth& curr_ptr_depth)
{
    const bool is_ref = IsRef ();
    const bool is_ptr = IsPtr ();
    const bool is_uninit = IsUninitialized();

    if (is_uninit)
        return false;

    // if the user has specified an element count, always print children
    // as it is explicit user demand being honored
    if (m_options.m_element_count > 0)
        return true;

    TypeSummaryImpl* entry = GetSummaryFormatter();

    if (m_options.m_use_objc)
        return false;

    if (is_failed_description || m_curr_depth < m_options.m_max_depth)
    {
        // We will show children for all concrete types. We won't show
        // pointer contents unless a pointer depth has been specified.
        // We won't reference contents unless the reference is the
        // root object (depth of zero).

        // Use a new temporary pointer depth in case we override the
        // current pointer depth below...

        if (is_ptr || is_ref)
        {
            // We have a pointer or reference whose value is an address.
            // Make sure that address is not NULL
            AddressType ptr_address_type;
            if (m_valobj->GetPointerValue (&ptr_address_type) == 0)
                return false;

            const bool is_root_level = m_curr_depth == 0;

            if (is_ref &&
                is_root_level)
            {
                // If this is the root object (depth is zero) that we are showing
                // and it is a reference, and no pointer depth has been supplied
                // print out what it references. Don't do this at deeper depths
                // otherwise we can end up with infinite recursion...
                return true;
            }

            return curr_ptr_depth.CanAllowExpansion(false, entry, m_valobj, m_summary);
        }

        return (!entry || entry->DoesPrintChildren(m_valobj) || m_summary.empty());
    }
    return false;
}

bool
ValueObjectPrinter::ShouldExpandEmptyAggregates ()
{
    TypeSummaryImpl* entry = GetSummaryFormatter();

    if (!entry)
        return true;

    return entry->DoesPrintEmptyAggregates();
}

ValueObject*
ValueObjectPrinter::GetValueObjectForChildrenGeneration ()
{
    return m_valobj;
}

void
ValueObjectPrinter::PrintChildrenPreamble ()
{
    if (m_options.m_flat_output)
    {
        if (ShouldPrintValueObject())
            m_stream->EOL();
    }
    else
    {
        if (ShouldPrintValueObject())
            m_stream->PutCString(IsRef () ? ": {\n" : " {\n");
        m_stream->IndentMore();
    }
}

void
ValueObjectPrinter::PrintChild (ValueObjectSP child_sp,
                                const DumpValueObjectOptions::PointerDepth& curr_ptr_depth)
{
    const uint32_t consumed_depth = (m_options.m_element_count == 0) ? 1 : 0;
    const bool does_consume_ptr_depth = ((IsPtr() && m_options.m_element_count == 0) || IsRef());

    DumpValueObjectOptions child_options(m_options);
    child_options.SetFormat(m_options.m_format).SetSummary().SetRootValueObjectName();
    child_options.SetScopeChecked(true).SetHideName(m_options.m_hide_name).SetHideValue(m_options.m_hide_value)
    .SetOmitSummaryDepth(child_options.m_omit_summary_depth > 1 ? child_options.m_omit_summary_depth - consumed_depth : 0)
    .SetElementCount(0);

    if (child_sp.get())
    {
        ValueObjectPrinter child_printer(child_sp.get(),
                                         m_stream,
                                         child_options,
                                         does_consume_ptr_depth ? --curr_ptr_depth : curr_ptr_depth,
                                         m_curr_depth + consumed_depth,
                                         m_printed_instance_pointers);
        child_printer.PrintValueObject();
    }
}

uint32_t
ValueObjectPrinter::GetMaxNumChildrenToPrint (bool& print_dotdotdot)
{
    ValueObject* synth_m_valobj = GetValueObjectForChildrenGeneration();

    if (m_options.m_element_count > 0)
        return m_options.m_element_count;

    size_t num_children = synth_m_valobj->GetNumChildren();
    print_dotdotdot = false;
    if (num_children)
    {
        const size_t max_num_children = m_valobj->GetTargetSP()->GetMaximumNumberOfChildrenToDisplay();

        if (num_children > max_num_children && !m_options.m_ignore_cap)
        {
            print_dotdotdot = true;
            return max_num_children;
        }
    }
    return num_children;
}

void
ValueObjectPrinter::PrintChildrenPostamble (bool print_dotdotdot)
{
    if (!m_options.m_flat_output)
    {
        if (print_dotdotdot)
        {
            m_valobj->GetTargetSP()->GetDebugger().GetCommandInterpreter().ChildrenTruncated();
            m_stream->Indent("...\n");
        }
        m_stream->IndentLess();
        m_stream->Indent("}\n");
    }
}

bool
ValueObjectPrinter::ShouldPrintEmptyBrackets (bool value_printed,
                                              bool summary_printed)
{
    ValueObject* synth_m_valobj = GetValueObjectForChildrenGeneration();

    if (!IsAggregate())
        return false;

    if (m_options.m_reveal_empty_aggregates == false)
    {
        if (value_printed || summary_printed)
            return false;
    }

    if (synth_m_valobj->MightHaveChildren())
        return true;

    if (m_val_summary_ok)
        return false;

    return true;
}

ValueObjectSP
ValueObjectPrinter::GenerateChild (ValueObject* synth_valobj, size_t idx)
{
    if (m_options.m_element_count > 0)
    {
        // if generating pointer-as-array children, use GetSyntheticArrayMember
        return synth_valobj->GetSyntheticArrayMember(idx, true);
    }
    else
    {
        // otherwise, do the usual thing
        return synth_valobj->GetChildAtIndex(idx, true);
    }
}

void
ValueObjectPrinter::PrintChildren (bool value_printed,
                                   bool summary_printed,
                                   const DumpValueObjectOptions::PointerDepth& curr_ptr_depth)
{
    ValueObject* synth_m_valobj = GetValueObjectForChildrenGeneration();

    bool print_dotdotdot = false;
    size_t num_children = GetMaxNumChildrenToPrint(print_dotdotdot);
    if (num_children)
    {
        bool any_children_printed = false;

        for (size_t idx=0; idx<num_children; ++idx)
        {
            if (ValueObjectSP child_sp = GenerateChild(synth_m_valobj, idx))
            {
                if (!any_children_printed)
                {
                    PrintChildrenPreamble ();
                    any_children_printed = true;
                }
                PrintChild (child_sp, curr_ptr_depth);
            }
        }

        if (any_children_printed)
            PrintChildrenPostamble (print_dotdotdot);
        else
        {
            if (ShouldPrintEmptyBrackets(value_printed, summary_printed))
            {
                if (ShouldPrintValueObject())
                    m_stream->PutCString(" {}\n");
                else
                    m_stream->EOL();
            }
            else
                m_stream->EOL();
        }
    }
    else if (ShouldPrintEmptyBrackets(value_printed, summary_printed))
    {
        // Aggregate, no children...
        if (ShouldPrintValueObject())
        {
            // if it has a synthetic value, then don't print {}, the synthetic children are probably only being used to vend a value
            if (m_valobj->DoesProvideSyntheticValue() || !ShouldExpandEmptyAggregates())
                m_stream->PutCString( "\n");
            else
                m_stream->PutCString(" {}\n");
        }
    }
    else
    {
        if (ShouldPrintValueObject())
            m_stream->EOL();
    }
}

bool
ValueObjectPrinter::PrintChildrenOneLiner (bool hide_names)
{
    if (!GetMostSpecializedValue () || m_valobj == nullptr)
        return false;

    ValueObject* synth_m_valobj = GetValueObjectForChildrenGeneration();

    bool print_dotdotdot = false;
    size_t num_children = GetMaxNumChildrenToPrint(print_dotdotdot);

    if (num_children)
    {
        m_stream->PutChar('(');

        for (uint32_t idx=0; idx<num_children; ++idx)
        {
            lldb::ValueObjectSP child_sp(synth_m_valobj->GetChildAtIndex(idx, true));
            if (child_sp)
                child_sp = child_sp->GetQualifiedRepresentationIfAvailable(m_options.m_use_dynamic, m_options.m_use_synthetic);
            if (child_sp)
            {
                if (idx)
                    m_stream->PutCString(", ");
                if (!hide_names)
                {
                    const char* name = child_sp.get()->GetName().AsCString();
                    if (name && *name)
                    {
                        m_stream->PutCString(name);
                        m_stream->PutCString(" = ");
                    }
                }
                child_sp->DumpPrintableRepresentation(*m_stream,
                                                      ValueObject::eValueObjectRepresentationStyleSummary,
                                                      m_options.m_format,
                                                      ValueObject::ePrintableRepresentationSpecialCasesDisable);
            }
        }

        if (print_dotdotdot)
            m_stream->PutCString(", ...)");
        else
            m_stream->PutChar(')');
    }
    return true;
}

void
ValueObjectPrinter::PrintChildrenIfNeeded (bool value_printed,
                                           bool summary_printed)
{
    // this flag controls whether we tried to display a description for this object and failed
    // if that happens, we want to display the children, if any
    bool is_failed_description = !PrintObjectDescriptionIfNeeded(value_printed, summary_printed);

    auto curr_ptr_depth = m_ptr_depth;
    bool print_children = ShouldPrintChildren (is_failed_description,curr_ptr_depth);
    bool print_oneline = (curr_ptr_depth.CanAllowExpansion() ||
                          m_options.m_show_types ||
                          !m_options.m_allow_oneliner_mode ||
                          m_options.m_flat_output ||
                          (m_options.m_element_count > 0) ||
                          m_options.m_show_location) ? false : DataVisualization::ShouldPrintAsOneLiner(*m_valobj);
    bool is_instance_ptr = IsInstancePointer();
    uint64_t instance_ptr_value = LLDB_INVALID_ADDRESS;

    if (print_children && is_instance_ptr)
    {
        instance_ptr_value = m_valobj->GetValueAsUnsigned(0);
        if (m_printed_instance_pointers->count(instance_ptr_value))
        {
            // we already printed this instance-is-pointer thing, so don't expand it
            m_stream->PutCString(" {...}\n");

            // we're done here - get out fast
            return;
        }
        else
            m_printed_instance_pointers->emplace(instance_ptr_value); // remember this guy for future reference
    }

    if (print_children)
    {
        if (print_oneline)
        {
            m_stream->PutChar(' ');
            PrintChildrenOneLiner (false);
            m_stream->EOL();
        }
        else
            PrintChildren (value_printed, summary_printed, curr_ptr_depth);
    }
    else if (m_curr_depth >= m_options.m_max_depth && IsAggregate() && ShouldPrintValueObject())
    {
        m_stream->PutCString("{...}\n");
    }
    else
        m_stream->EOL();
}

bool
ValueObjectPrinter::ShouldPrintValidation ()
{
    return m_options.m_run_validator;
}

bool
ValueObjectPrinter::PrintValidationMarkerIfNeeded ()
{
    if (!ShouldPrintValidation())
        return false;

    m_validation = m_valobj->GetValidationStatus();

    if (TypeValidatorResult::Failure == m_validation.first)
    {
        m_stream->Printf("! ");
        return true;
    }

    return false;
}

bool
ValueObjectPrinter::PrintValidationErrorIfNeeded ()
{
    if (!ShouldPrintValidation())
        return false;

    if (TypeValidatorResult::Success == m_validation.first)
        return false;

    if (m_validation.second.empty())
        m_validation.second.assign("unknown error");

    m_stream->Printf(" ! validation error: %s", m_validation.second.c_str());
    m_stream->EOL();

    return true;
}