JUCE/modules/juce_audio_processors/utilities/juce_AudioProcessorValueTreeState.cpp

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

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2020 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For this technical preview, this file is not subject to commercial licensing.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

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

namespace juce
{

//==============================================================================
AudioProcessorValueTreeState::Parameter::Parameter (const String& parameterID,
                                                    const String& parameterName,
                                                    const String& labelText,
                                                    NormalisableRange<float> valueRange,
                                                    float defaultParameterValue,
                                                    std::function<String(float)> valueToTextFunction,
                                                    std::function<float(const String&)> textToValueFunction,
                                                    bool isMetaParameter,
                                                    bool isAutomatableParameter,
                                                    bool isDiscrete,
                                                    AudioProcessorParameter::Category parameterCategory,
                                                    bool isBoolean)
    : AudioParameterFloat (parameterID,
                           parameterName,
                           valueRange,
                           defaultParameterValue,
                           labelText,
                           parameterCategory,
                           valueToTextFunction == nullptr ? std::function<String(float v, int)>()
                                                          : [valueToTextFunction](float v, int) { return valueToTextFunction (v); },
                           std::move (textToValueFunction)),
      unsnappedDefault (valueRange.convertTo0to1 (defaultParameterValue)),
      metaParameter (isMetaParameter),
      automatable (isAutomatableParameter),
      discrete (isDiscrete),
      boolean (isBoolean)
{
}

float AudioProcessorValueTreeState::Parameter::getDefaultValue() const  { return unsnappedDefault; }
int AudioProcessorValueTreeState::Parameter::getNumSteps() const        { return RangedAudioParameter::getNumSteps(); }

bool AudioProcessorValueTreeState::Parameter::isMetaParameter() const   { return metaParameter; }
bool AudioProcessorValueTreeState::Parameter::isAutomatable() const     { return automatable; }
bool AudioProcessorValueTreeState::Parameter::isDiscrete() const        { return discrete; }
bool AudioProcessorValueTreeState::Parameter::isBoolean() const         { return boolean; }

void AudioProcessorValueTreeState::Parameter::valueChanged (float newValue)
{
    if (lastValue == newValue)
        return;

    lastValue = newValue;

    if (onValueChanged != nullptr)
        onValueChanged();
}

//==============================================================================
class AudioProcessorValueTreeState::ParameterAdapter   : private AudioProcessorParameter::Listener
{
private:
    using Listener = AudioProcessorValueTreeState::Listener;

public:
    explicit ParameterAdapter (RangedAudioParameter& parameterIn)
        : parameter (parameterIn),
          // For legacy reasons, the unnormalised value should *not* be snapped on construction
          unnormalisedValue (getRange().convertFrom0to1 (parameter.getDefaultValue()))
    {
        parameter.addListener (this);

        if (auto* ptr = dynamic_cast<Parameter*> (&parameter))
            ptr->onValueChanged = [this] { parameterValueChanged ({}, {}); };
    }

    ~ParameterAdapter() override        { parameter.removeListener (this); }

    void addListener (Listener* l)      { listeners.add (l); }
    void removeListener (Listener* l)   { listeners.remove (l); }

    RangedAudioParameter& getParameter()                { return parameter; }
    const RangedAudioParameter& getParameter() const    { return parameter; }

    const NormalisableRange<float>& getRange() const    { return parameter.getNormalisableRange(); }

    float getDenormalisedDefaultValue() const    { return denormalise (parameter.getDefaultValue()); }

    void setDenormalisedValue (float value)
    {
        if (value == unnormalisedValue)
            return;

        setNormalisedValue (normalise (value));
    }

    float getDenormalisedValueForText (const String& text) const
    {
        return denormalise (parameter.getValueForText (text));
    }

    String getTextForDenormalisedValue (float value) const
    {
        return parameter.getText (normalise (value), 0);
    }

    float getDenormalisedValue() const                { return unnormalisedValue; }
    std::atomic<float>& getRawDenormalisedValue()     { return unnormalisedValue; }

    bool flushToTree (const Identifier& key, UndoManager* um)
    {
        auto needsUpdateTestValue = true;

        if (! needsUpdate.compare_exchange_strong (needsUpdateTestValue, false))
            return false;

        if (auto valueProperty = tree.getPropertyPointer (key))
        {
            if ((float) *valueProperty != unnormalisedValue)
            {
                ScopedValueSetter<bool> svs (ignoreParameterChangedCallbacks, true);
                tree.setProperty (key, unnormalisedValue.load(), um);
            }
        }
        else
        {
            tree.setProperty (key, unnormalisedValue.load(), nullptr);
        }

        return true;
    }

    ValueTree tree;

private:
    void parameterGestureChanged (int, bool) override {}

    void parameterValueChanged (int, float) override
    {
        const auto newValue = denormalise (parameter.getValue());

        if (unnormalisedValue == newValue && ! listenersNeedCalling)
            return;

        unnormalisedValue = newValue;
        listeners.call ([=](Listener& l) { l.parameterChanged (parameter.paramID, unnormalisedValue); });
        listenersNeedCalling = false;
        needsUpdate = true;
    }

    float denormalise (float normalised) const
    {
        return getParameter().convertFrom0to1 (normalised);
    }

    float normalise (float denormalised) const
    {
        return getParameter().convertTo0to1 (denormalised);
    }

    void setNormalisedValue (float value)
    {
        if (ignoreParameterChangedCallbacks)
            return;

        parameter.setValueNotifyingHost (value);
    }

    RangedAudioParameter& parameter;
    ListenerList<Listener> listeners;
    std::atomic<float> unnormalisedValue { 0.0f };
    std::atomic<bool> needsUpdate { true }, listenersNeedCalling { true };
    bool ignoreParameterChangedCallbacks { false };
};

//==============================================================================
AudioProcessorValueTreeState::AudioProcessorValueTreeState (AudioProcessor& processorToConnectTo,
                                                            UndoManager* undoManagerToUse,
                                                            const Identifier& valueTreeType,
                                                            ParameterLayout parameterLayout)
    : AudioProcessorValueTreeState (processorToConnectTo, undoManagerToUse)
{
    struct PushBackVisitor : ParameterLayout::Visitor
    {
        explicit PushBackVisitor (AudioProcessorValueTreeState& stateIn)
            : state (&stateIn) {}

        void visit (std::unique_ptr<RangedAudioParameter> param) const override
        {
            if (param == nullptr)
            {
                jassertfalse;
                return;
            }

            state->addParameterAdapter (*param);
            state->processor.addParameter (param.release());
        }

        void visit (std::unique_ptr<AudioProcessorParameterGroup> group) const override
        {
            if (group == nullptr)
            {
                jassertfalse;
                return;
            }

            for (const auto param : group->getParameters (true))
            {
                if (const auto rangedParam = dynamic_cast<RangedAudioParameter*> (param))
                {
                    state->addParameterAdapter (*rangedParam);
                }
                else
                {
                    // If you hit this assertion then you are attempting to add a parameter that is
                    // not derived from RangedAudioParameter to the AudioProcessorValueTreeState.
                    jassertfalse;
                }
            }

            state->processor.addParameterGroup (move (group));
        }

        AudioProcessorValueTreeState* state;
    };

    for (auto& item : parameterLayout.parameters)
        item->accept (PushBackVisitor (*this));

    state = ValueTree (valueTreeType);
}

AudioProcessorValueTreeState::AudioProcessorValueTreeState (AudioProcessor& p, UndoManager* um)
    : processor (p), undoManager (um)
{
    startTimerHz (10);
    state.addListener (this);
}

AudioProcessorValueTreeState::~AudioProcessorValueTreeState()
{
    stopTimer();
}

//==============================================================================
RangedAudioParameter* AudioProcessorValueTreeState::createAndAddParameter (const String& paramID,
                                                                           const String& paramName,
                                                                           const String& labelText,
                                                                           NormalisableRange<float> range,
                                                                           float defaultVal,
                                                                           std::function<String(float)> valueToTextFunction,
                                                                           std::function<float(const String&)> textToValueFunction,
                                                                           bool isMetaParameter,
                                                                           bool isAutomatableParameter,
                                                                           bool isDiscreteParameter,
                                                                           AudioProcessorParameter::Category category,
                                                                           bool isBooleanParameter)
{
    return createAndAddParameter (std::make_unique<Parameter> (paramID,
                                                               paramName,
                                                               labelText,
                                                               range,
                                                               defaultVal,
                                                               std::move (valueToTextFunction),
                                                               std::move (textToValueFunction),
                                                               isMetaParameter,
                                                               isAutomatableParameter,
                                                               isDiscreteParameter,
                                                               category,
                                                               isBooleanParameter));
}

RangedAudioParameter* AudioProcessorValueTreeState::createAndAddParameter (std::unique_ptr<RangedAudioParameter> param)
{
    if (param == nullptr)
        return nullptr;

    // All parameters must be created before giving this manager a ValueTree state!
    jassert (! state.isValid());

    if (getParameter (param->paramID) != nullptr)
        return nullptr;

    addParameterAdapter (*param);

    processor.addParameter (param.get());

    return param.release();
}

//==============================================================================
void AudioProcessorValueTreeState::addParameterAdapter (RangedAudioParameter& param)
{
    adapterTable.emplace (param.paramID, std::make_unique<ParameterAdapter> (param));
}

AudioProcessorValueTreeState::ParameterAdapter* AudioProcessorValueTreeState::getParameterAdapter (StringRef paramID) const
{
    auto it = adapterTable.find (paramID);
    return it == adapterTable.end() ? nullptr : it->second.get();
}

void AudioProcessorValueTreeState::addParameterListener (StringRef paramID, Listener* listener)
{
    if (auto* p = getParameterAdapter (paramID))
        p->addListener (listener);
}

void AudioProcessorValueTreeState::removeParameterListener (StringRef paramID, Listener* listener)
{
    if (auto* p = getParameterAdapter (paramID))
        p->removeListener (listener);
}

Value AudioProcessorValueTreeState::getParameterAsValue (StringRef paramID) const
{
    if (auto* adapter = getParameterAdapter (paramID))
        if (adapter->tree.isValid())
            return adapter->tree.getPropertyAsValue (valuePropertyID, undoManager);

    return {};
}

NormalisableRange<float> AudioProcessorValueTreeState::getParameterRange (StringRef paramID) const noexcept
{
    if (auto* p = getParameterAdapter (paramID))
        return p->getRange();

    return {};
}

RangedAudioParameter* AudioProcessorValueTreeState::getParameter (StringRef paramID) const noexcept
{
    if (auto adapter = getParameterAdapter (paramID))
        return &adapter->getParameter();

    return nullptr;
}

std::atomic<float>* AudioProcessorValueTreeState::getRawParameterValue (StringRef paramID) const noexcept
{
    if (auto* p = getParameterAdapter (paramID))
        return &p->getRawDenormalisedValue();

    return nullptr;
}

ValueTree AudioProcessorValueTreeState::copyState()
{
    ScopedLock lock (valueTreeChanging);
    flushParameterValuesToValueTree();
    return state.createCopy();
}

void AudioProcessorValueTreeState::replaceState (const ValueTree& newState)
{
    ScopedLock lock (valueTreeChanging);

    state = newState;

    if (undoManager != nullptr)
        undoManager->clearUndoHistory();
}

void AudioProcessorValueTreeState::setNewState (ValueTree vt)
{
    jassert (vt.getParent() == state);

    if (auto* p = getParameterAdapter (vt.getProperty (idPropertyID).toString()))
    {
        p->tree = vt;
        p->setDenormalisedValue (p->tree.getProperty (valuePropertyID, p->getDenormalisedDefaultValue()));
    }
}

void AudioProcessorValueTreeState::updateParameterConnectionsToChildTrees()
{
    ScopedLock lock (valueTreeChanging);

    for (auto& p : adapterTable)
        p.second->tree = ValueTree();

    for (const auto& child : state)
        setNewState (child);

    for (auto& p : adapterTable)
    {
        auto& adapter = *p.second;

        if (! adapter.tree.isValid())
        {
            adapter.tree = ValueTree (valueType);
            adapter.tree.setProperty (idPropertyID, adapter.getParameter().paramID, nullptr);
            state.appendChild (adapter.tree, nullptr);
        }
    }

    flushParameterValuesToValueTree();
}

void AudioProcessorValueTreeState::valueTreePropertyChanged (ValueTree& tree, const Identifier&)
{
    if (tree.hasType (valueType) && tree.getParent() == state)
        setNewState (tree);
}

void AudioProcessorValueTreeState::valueTreeChildAdded (ValueTree& parent, ValueTree& tree)
{
    if (parent == state && tree.hasType (valueType))
        setNewState (tree);
}

void AudioProcessorValueTreeState::valueTreeRedirected (ValueTree& v)
{
    if (v == state)
        updateParameterConnectionsToChildTrees();
}

bool AudioProcessorValueTreeState::flushParameterValuesToValueTree()
{
    ScopedLock lock (valueTreeChanging);

    bool anyUpdated = false;

    for (auto& p : adapterTable)
        anyUpdated |= p.second->flushToTree (valuePropertyID, undoManager);

    return anyUpdated;
}

void AudioProcessorValueTreeState::timerCallback()
{
    auto anythingUpdated = flushParameterValuesToValueTree();

    startTimer (anythingUpdated ? 1000 / 50
                                : jlimit (50, 500, getTimerInterval() + 20));
}

//==============================================================================
template <typename Attachment, typename Control>
std::unique_ptr<Attachment> makeAttachment (const AudioProcessorValueTreeState& stateToUse,
                                            const String& parameterID,
                                            Control& control)
{
    if (auto* parameter = stateToUse.getParameter (parameterID))
        return std::make_unique<Attachment> (*parameter, control, stateToUse.undoManager);

    jassertfalse;
    return nullptr;
}

AudioProcessorValueTreeState::SliderAttachment::SliderAttachment (AudioProcessorValueTreeState& stateToUse,
                                                                  const String& parameterID,
                                                                  Slider& slider)
    : attachment (makeAttachment<SliderParameterAttachment> (stateToUse, parameterID, slider))
{
}

AudioProcessorValueTreeState::ComboBoxAttachment::ComboBoxAttachment (AudioProcessorValueTreeState& stateToUse,
                                                                      const String& parameterID,
                                                                      ComboBox& combo)
    : attachment (makeAttachment<ComboBoxParameterAttachment> (stateToUse, parameterID, combo))
{
}

AudioProcessorValueTreeState::ButtonAttachment::ButtonAttachment (AudioProcessorValueTreeState& stateToUse,
                                                                  const String& parameterID,
                                                                  Button& button)
    : attachment (makeAttachment<ButtonParameterAttachment> (stateToUse, parameterID, button))
{
}

//==============================================================================
//==============================================================================
#if JUCE_UNIT_TESTS

struct ParameterAdapterTests  : public UnitTest
{
    ParameterAdapterTests()
        : UnitTest ("Parameter Adapter", UnitTestCategories::audioProcessorParameters)
    {}

    void runTest() override
    {
        beginTest ("The default value is returned correctly");
        {
            const auto test = [&] (NormalisableRange<float> range, float value)
            {
                AudioParameterFloat param ({}, {}, range, value, {});

                AudioProcessorValueTreeState::ParameterAdapter adapter (param);

                expectEquals (adapter.getDenormalisedDefaultValue(), value);
            };

            test ({ -100, 100 }, 0);
            test ({ -2.5, 12.5 }, 10);
        }

        beginTest ("Denormalised parameter values can be retrieved");
        {
            const auto test = [&](NormalisableRange<float> range, float value)
            {
                AudioParameterFloat param ({}, {}, range, {}, {});
                AudioProcessorValueTreeState::ParameterAdapter adapter (param);

                adapter.setDenormalisedValue (value);

                expectEquals (adapter.getDenormalisedValue(), value);
                expectEquals (adapter.getRawDenormalisedValue().load(), value);
            };

            test ({ -20, -10 }, -15);
            test ({ 0, 7.5 }, 2.5);
        }

        beginTest ("Floats can be converted to text");
        {
            const auto test = [&](NormalisableRange<float> range, float value, String expected)
            {
                AudioParameterFloat param ({}, {}, range, {}, {});
                AudioProcessorValueTreeState::ParameterAdapter adapter (param);

                expectEquals (adapter.getTextForDenormalisedValue (value), expected);
            };

            test ({ -100, 100 }, 0, "0.0000000");
            test ({ -2.5, 12.5 }, 10, "10.0000000");
            test ({ -20, -10 }, -15, "-15.0000000");
            test ({ 0, 7.5 }, 2.5, "2.5000000");
        }

        beginTest ("Text can be converted to floats");
        {
            const auto test = [&](NormalisableRange<float> range, String text, float expected)
            {
                AudioParameterFloat param ({}, {}, range, {}, {});
                AudioProcessorValueTreeState::ParameterAdapter adapter (param);

                expectEquals (adapter.getDenormalisedValueForText (text), expected);
            };

            test ({ -100, 100 }, "0.0", 0);
            test ({ -2.5, 12.5 }, "10.0", 10);
            test ({ -20, -10 }, "-15.0", -15);
            test ({ 0, 7.5 }, "2.5", 2.5);
        }
    }
};

static ParameterAdapterTests parameterAdapterTests;

namespace
{
template <typename ValueType>
inline bool operator== (const NormalisableRange<ValueType>& a,
                        const NormalisableRange<ValueType>& b)
{
    return std::tie (a.start, a.end, a.interval, a.skew, a.symmetricSkew)
           == std::tie (b.start, b.end, b.interval, b.skew, b.symmetricSkew);
}

template <typename ValueType>
inline bool operator!= (const NormalisableRange<ValueType>& a,
                        const NormalisableRange<ValueType>& b)
{
    return ! (a == b);
}
} // namespace

class AudioProcessorValueTreeStateTests  : public UnitTest
{
private:
    using Parameter = AudioProcessorValueTreeState::Parameter;
    using ParameterGroup = AudioProcessorParameterGroup;
    using ParameterLayout = AudioProcessorValueTreeState::ParameterLayout;

    class TestAudioProcessor : public AudioProcessor
    {
    public:
        TestAudioProcessor() = default;

        explicit TestAudioProcessor (ParameterLayout layout)
            : state (*this, nullptr, "state", std::move (layout)) {}

        const String getName() const override { return {}; }
        void prepareToPlay (double, int) override {}
        void releaseResources() override {}
        void processBlock (AudioBuffer<float>&, MidiBuffer&) override {}
        using AudioProcessor::processBlock;
        double getTailLengthSeconds() const override { return {}; }
        bool acceptsMidi() const override { return {}; }
        bool producesMidi() const override { return {}; }
        AudioProcessorEditor* createEditor() override { return {}; }
        bool hasEditor() const override { return {}; }
        int getNumPrograms() override { return 1; }
        int getCurrentProgram() override { return {}; }
        void setCurrentProgram (int) override {}
        const String getProgramName (int) override { return {}; }
        void changeProgramName (int, const String&) override {}
        void getStateInformation (MemoryBlock&) override {}
        void setStateInformation (const void*, int) override {}

        AudioProcessorValueTreeState state { *this, nullptr };
    };

    struct Listener final : public AudioProcessorValueTreeState::Listener
    {
        void parameterChanged (const String& idIn, float valueIn) override
        {
            id = idIn;
            value = valueIn;
        }

        String id;
        float value{};
    };

public:
    AudioProcessorValueTreeStateTests()
        : UnitTest ("Audio Processor Value Tree State", UnitTestCategories::audioProcessorParameters)
    {}

    void runTest() override
    {
        ScopedJuceInitialiser_GUI scopedJuceInitialiser_gui;

        beginTest ("After calling createAndAddParameter, the number of parameters increases by one");
        {
            TestAudioProcessor proc;

            proc.state.createAndAddParameter (std::make_unique<Parameter> (String(), String(), String(), NormalisableRange<float>(),
                                                                           0.0f, nullptr, nullptr));

            expectEquals (proc.getParameters().size(), 1);
        }

        beginTest ("After creating a normal named parameter, we can later retrieve that parameter");
        {
            TestAudioProcessor proc;

            const auto key = "id";
            const auto param = proc.state.createAndAddParameter (std::make_unique<Parameter> (key, String(), String(), NormalisableRange<float>(),
                                                                                              0.0f, nullptr, nullptr));

            expect (proc.state.getParameter (key) == param);
        }

        beginTest ("After construction, the value tree has the expected format");
        {
            TestAudioProcessor proc ({
                std::make_unique<AudioProcessorParameterGroup> ("", "", "",
                    std::make_unique<AudioParameterBool> ("a", "", false),
                    std::make_unique<AudioParameterFloat> ("b", "", NormalisableRange<float>{}, 0.0f)),
                std::make_unique<AudioProcessorParameterGroup> ("", "", "",
                    std::make_unique<AudioParameterInt> ("c", "", 0, 1, 0),
                    std::make_unique<AudioParameterChoice> ("d", "", StringArray { "foo", "bar" }, 0)) });

            const auto valueTree = proc.state.copyState();

            expectEquals (valueTree.getNumChildren(), 4);

            for (auto child : valueTree)
            {
                expect (child.hasType ("PARAM"));
                expect (child.hasProperty ("id"));
                expect (child.hasProperty ("value"));
            }
        }

        beginTest ("Meta parameters can be created");
        {
            TestAudioProcessor proc;

            const auto key = "id";
            const auto param = proc.state.createAndAddParameter (std::make_unique<Parameter> (key, String(), String(), NormalisableRange<float>(),
                                                                                              0.0f, nullptr, nullptr, true));

            expect (param->isMetaParameter());
        }

        beginTest ("Automatable parameters can be created");
        {
            TestAudioProcessor proc;

            const auto key = "id";
            const auto param = proc.state.createAndAddParameter (std::make_unique<Parameter> (key, String(), String(), NormalisableRange<float>(),
                                                                                              0.0f, nullptr, nullptr, false, true));

            expect (param->isAutomatable());
        }

        beginTest ("Discrete parameters can be created");
        {
            TestAudioProcessor proc;

            const auto key = "id";
            const auto param = proc.state.createAndAddParameter (std::make_unique<Parameter> (key, String(), String(), NormalisableRange<float>(),
                                                                                              0.0f, nullptr, nullptr, false, false, true));

            expect (param->isDiscrete());
        }

        beginTest ("Custom category parameters can be created");
        {
            TestAudioProcessor proc;

            const auto key = "id";
            const auto param = proc.state.createAndAddParameter (std::make_unique<Parameter> (key, String(), String(), NormalisableRange<float>(),
                                                                                              0.0f, nullptr, nullptr, false, false, false,
                                                                                              AudioProcessorParameter::Category::inputMeter));

            expect (param->category == AudioProcessorParameter::Category::inputMeter);
        }

        beginTest ("Boolean parameters can be created");
        {
            TestAudioProcessor proc;

            const auto key = "id";
            const auto param = proc.state.createAndAddParameter (std::make_unique<Parameter> (key, String(), String(), NormalisableRange<float>(),
                                                                                              0.0f, nullptr, nullptr, false, false, false,
                                                                                              AudioProcessorParameter::Category::genericParameter, true));

            expect (param->isBoolean());
        }

        beginTest ("After creating a custom named parameter, we can later retrieve that parameter");
        {
            const auto key = "id";
            auto param = std::make_unique<AudioParameterBool> (key, "", false);
            const auto paramPtr = param.get();

            TestAudioProcessor proc (std::move (param));

            expect (proc.state.getParameter (key) == paramPtr);
        }

        beginTest ("After adding a normal parameter that already exists, the AudioProcessor parameters are unchanged");
        {
            TestAudioProcessor proc;
            const auto key = "id";
            const auto param = proc.state.createAndAddParameter (std::make_unique<Parameter> (key, String(), String(), NormalisableRange<float>(),
                                                                                              0.0f, nullptr, nullptr));

            proc.state.createAndAddParameter (std::make_unique<Parameter> (key, String(), String(), NormalisableRange<float>(),
                                                                           0.0f, nullptr, nullptr));

            expectEquals (proc.getParameters().size(), 1);
            expect (proc.getParameters().getFirst() == param);
        }

        beginTest ("After setting a parameter value, that value is reflected in the state");
        {
            TestAudioProcessor proc;
            const auto key = "id";
            const auto param = proc.state.createAndAddParameter (std::make_unique<Parameter> (key, String(), String(), NormalisableRange<float>(),
                                                                                              0.0f, nullptr, nullptr));

            const auto value = 0.5f;
            param->setValueNotifyingHost (value);

            expectEquals (proc.state.getRawParameterValue (key)->load(), value);
        }

        beginTest ("After adding an APVTS::Parameter, its value is the default value");
        {
            TestAudioProcessor proc;
            const auto key = "id";
            const auto value = 5.0f;

            proc.state.createAndAddParameter (std::make_unique<Parameter> (
                key,
                String(),
                String(),
                NormalisableRange<float> (0.0f, 100.0f, 10.0f),
                value,
                nullptr,
                nullptr));

            expectEquals (proc.state.getRawParameterValue (key)->load(), value);
        }

        beginTest ("Listeners receive notifications when parameters change");
        {
            Listener listener;
            TestAudioProcessor proc;
            const auto key = "id";
            const auto param = proc.state.createAndAddParameter (std::make_unique<Parameter> (key, String(), String(), NormalisableRange<float>(),
                                                                                              0.0f, nullptr, nullptr));
            proc.state.addParameterListener (key, &listener);

            const auto value = 0.5f;
            param->setValueNotifyingHost (value);

            expectEquals (listener.id, String { key });
            expectEquals (listener.value, value);
        }

        beginTest ("Bool parameters have a range of 0-1");
        {
            const auto key = "id";

            TestAudioProcessor proc (std::make_unique<AudioParameterBool> (key, "", false));

            expect (proc.state.getParameterRange (key) == NormalisableRange<float> (0.0f, 1.0f, 1.0f));
        }

        beginTest ("Float parameters retain their specified range");
        {
            const auto key = "id";
            const auto range = NormalisableRange<float> { -100, 100, 0.7f, 0.2f, true };

            TestAudioProcessor proc (std::make_unique<AudioParameterFloat> (key, "", range, 0.0f));

            expect (proc.state.getParameterRange (key) == range);
        }

        beginTest ("Int parameters retain their specified range");
        {
            const auto key = "id";
            const auto min = -27;
            const auto max = 53;

            TestAudioProcessor proc (std::make_unique<AudioParameterInt> (key, "", min, max, 0));

            expect (proc.state.getParameterRange (key) == NormalisableRange<float> (float (min), float (max), 1.0f));
        }

        beginTest ("Choice parameters retain their specified range");
        {
            const auto key = "id";
            const auto choices = StringArray { "", "", "" };

            TestAudioProcessor proc (std::make_unique<AudioParameterChoice> (key, "", choices, 0));

            expect (proc.state.getParameterRange (key) == NormalisableRange<float> (0.0f, (float) (choices.size() - 1), 1.0f));
            expect (proc.state.getParameter (key)->getNumSteps() == choices.size());
        }

        beginTest ("When the parameter value is changed, normal parameter values are updated");
        {
            TestAudioProcessor proc;
            const auto key = "id";
            const auto initialValue = 0.2f;
            auto param = proc.state.createAndAddParameter (std::make_unique<Parameter> (key, String(), String(), NormalisableRange<float>(),
                                                                                        initialValue, nullptr, nullptr));
            proc.state.state = ValueTree { "state" };

            auto value = proc.state.getParameterAsValue (key);
            expectEquals (float (value.getValue()), initialValue);

            const auto newValue = 0.75f;
            value = newValue;

            expectEquals (param->getValue(), newValue);
            expectEquals (proc.state.getRawParameterValue (key)->load(), newValue);
        }

        beginTest ("When the parameter value is changed, custom parameter values are updated");
        {
            const auto key = "id";
            const auto choices = StringArray ("foo", "bar", "baz");
            auto param = std::make_unique<AudioParameterChoice> (key, "", choices, 0);
            const auto paramPtr = param.get();
            TestAudioProcessor proc (std::move (param));

            const auto newValue = 2.0f;
            auto value = proc.state.getParameterAsValue (key);
            value = newValue;

            expectEquals (paramPtr->getCurrentChoiceName(), choices[int (newValue)]);
            expectEquals (proc.state.getRawParameterValue (key)->load(), newValue);
        }

        beginTest ("When the parameter value is changed, listeners are notified");
        {
            Listener listener;
            TestAudioProcessor proc;
            const auto key = "id";
            proc.state.createAndAddParameter (std::make_unique<Parameter> (key, String(), String(), NormalisableRange<float>(),
                                                                           0.0f, nullptr, nullptr));
            proc.state.addParameterListener (key, &listener);
            proc.state.state = ValueTree { "state" };

            const auto newValue = 0.75f;
            proc.state.getParameterAsValue (key) = newValue;

            expectEquals (listener.value, newValue);
            expectEquals (listener.id, String { key });
        }

        beginTest ("When the parameter value is changed, listeners are notified");
        {
            const auto key = "id";
            const auto choices = StringArray { "foo", "bar", "baz" };
            Listener listener;
            TestAudioProcessor proc (std::make_unique<AudioParameterChoice> (key, "", choices, 0));
            proc.state.addParameterListener (key, &listener);

            const auto newValue = 2.0f;
            proc.state.getParameterAsValue (key) = newValue;

            expectEquals (listener.value, newValue);
            expectEquals (listener.id, String (key));
        }
    }
};

static AudioProcessorValueTreeStateTests audioProcessorValueTreeStateTests;

#endif

} // namespace juce