juce_Value.h

/*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2022 - Raw Material Software Limited
 
   JUCE is an open source library subject to commercial or open-source
   licensing.
 
   By using JUCE, you agree to the terms of both the JUCE 7 End-User License
   Agreement and JUCE Privacy Policy.
 
   End User License Agreement: www.juce.com/juce-7-licence
   Privacy Policy: www.juce.com/juce-privacy-policy
 
   Or: You may also use this code under the terms of the GPL v3 (see
   www.gnu.org/licenses).
 
   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
{
 
//==============================================================================
class JUCE_API  Value  final
{
public:
    //==============================================================================
    Value();

    Value (const Value& other);

    explicit Value (const var& initialValue);

    Value (Value&&) noexcept;

    ~Value();
 
    //==============================================================================
    var getValue() const;

    operator var() const;

    String toString() const;

    void setValue (const var& newValue);

    Value& operator= (const var& newValue);

    Value& operator= (Value&&) noexcept;

    void referTo (const Value& valueToReferTo);

    bool refersToSameSourceAs (const Value& other) const;

    bool operator== (const Value& other) const;

    bool operator!= (const Value& other) const;
 
    //==============================================================================
    class JUCE_API  Listener
    {
    public:
        Listener() = default;
        virtual ~Listener() = default;

        virtual void valueChanged (Value& value) = 0;
    };

    void addListener (Listener* listener);

    void removeListener (Listener* listener);
 
 
    //==============================================================================
    class JUCE_API  ValueSource   : public ReferenceCountedObject,
                                    private AsyncUpdater
    {
    public:
        ValueSource();
        ~ValueSource() override;

        virtual var getValue() const = 0;

        virtual void setValue (const var& newValue) = 0;

        void sendChangeMessage (bool dispatchSynchronously);
 
    protected:
        //==============================================================================
        friend class Value;
        SortedSet<Value*> valuesWithListeners;
 
    private:
        void handleAsyncUpdate() override;
 
        JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ValueSource)
    };
 
 
    //==============================================================================
    explicit Value (ValueSource* valueSource);

    ValueSource& getValueSource() noexcept          { return *value; }
 
 
private:
    //==============================================================================
    friend class ValueSource;
    ReferenceCountedObjectPtr<ValueSource> value;
    ListenerList<Listener> listeners;
 
    void callListeners();
    void removeFromListenerList();
 
    // This is disallowed to avoid confusion about whether it should
    // do a by-value or by-reference copy.
    Value& operator= (const Value&) = delete;
 
    // This declaration prevents accidental construction from an integer of 0,
    // which is possible in some compilers via an implicit cast to a pointer.
    explicit Value (void*) = delete;
};

OutputStream& JUCE_CALLTYPE operator<< (OutputStream&, const Value&);
 
 
} // namespace juce