JUCE/modules/juce_javascript/javascript/juce_JSCursor.cpp

/*
  ==============================================================================

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*/

namespace juce
{

JSCursor::JSCursor (JSObject rootIn) : root (std::move (rootIn))
{
}

var JSCursor::get() const
{
    if (const auto resolved = getFullResolution())
        return resolved->get();

    return var::undefined();
}

void JSCursor::set (const var& value) const
{
    const auto resolved = getPartialResolution();

    if (! resolved.has_value())
    {
        jassertfalse;  // Can't resolve an Object to change along the path stored in the cursor
        return;
    }

    const auto& [object, property] = *resolved;

    if (! property.has_value())
    {
        jassertfalse;  // Can't set the value of the root Object
        return;
    }

    if (auto* prop = std::get_if<Identifier> (&(*property)))
    {
        object.setProperty (*prop, value);
        return;
    }

    if (auto* prop = std::get_if<int64> (&(*property)))
    {
        object.setProperty (*prop, value);
        return;
    }
}

JSCursor JSCursor::getChild (const Identifier& name) const
{
    auto copy = *this;
    copy.path.emplace_back (name);
    return copy;
}

JSCursor JSCursor::operator[] (const Identifier& name) const
{
    return getChild (name);
}

JSCursor JSCursor::getChild (int64 index) const
{
    auto copy = *this;
    copy.path.emplace_back (index);
    return copy;
}

JSCursor JSCursor::operator[] (int64 index) const
{
    return getChild (index);
}

JSObject JSCursor::getOrCreateObject() const
{
    const auto resolved = getPartialResolution();
    jassert (resolved.has_value());

    const auto& [object, property] = *resolved;

    if (! property.has_value())
        return object;

    auto* integerValue = std::get_if<int64> (&(*property));

    jassert   (integerValue == nullptr
            || (object.isArray() && (*integerValue) < object.getSize()));

    if (integerValue != nullptr)
        return object[*integerValue];

    auto* prop = std::get_if<Identifier> (&(*property));
    jassert(prop != nullptr);
    return object[*prop];
}

bool JSCursor::isValid() const
{
    return getPartialResolution().has_value();
}

bool JSCursor::isArray() const
{
    if (auto resolved = getFullResolution())
        return resolved->isArray();

    return false;
}

var JSCursor::invoke (Span<const var> args, Result* result) const
{
    const auto resolved = getPartialResolution();

    if (! resolved.has_value())
    {
        jassertfalse;
        return {};
    }

    const auto& [object, property] = *resolved;
    if (! property.has_value())
    {
        jassertfalse;
        return {};
    }

    return object.invokeMethod (*std::get_if<Identifier> (&(*property)), args, result);
}

std::optional<JSObject> JSCursor::resolve (JSObject object, Property property)
{
    if (auto* index = std::get_if<int64> (&property))
    {
        if (! object.isArray())
            return std::nullopt;

        if (! (*index < object.getSize()))
            return std::nullopt;

        return object[*index];
    }

    if (auto* key = std::get_if<Identifier> (&property))
    {
        if (! object.hasProperty (*key))
            return std::nullopt;

        return object[*key];
    }

    jassertfalse;
    return std::nullopt;
}

std::optional<JSCursor::PartialResolution> JSCursor::getPartialResolution() const
{
    auto object = root;

    for (int i = 0, iEnd = (int) path.size() - 1; i < iEnd; ++i)
    {
        const auto& property = path[(size_t) i];
        auto objectOpt = resolve (object, property);

        if (! objectOpt.has_value())
            return std::nullopt;

        object = *objectOpt;
    }

    return std::make_optional<PartialResolution> (std::move (object),
                                                  path.empty() ? std::nullopt
                                                               : std::make_optional (path.back()));
}

std::optional<JSObject> JSCursor::getFullResolution() const
{
    if (auto partiallyResolved = getPartialResolution())
    {
        if (! partiallyResolved->second.has_value())
            return partiallyResolved->first;

        return resolve (partiallyResolved->first, *(partiallyResolved->second));
    }

    return std::nullopt;
}

} // namespace juce