juce_CachedValue.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
{
 
//==============================================================================
template <typename Type>
class CachedValue   : private ValueTree::Listener
{
public:
    //==============================================================================
    CachedValue();

    CachedValue (ValueTree& tree, const Identifier& propertyID,
                 UndoManager* undoManager);

    CachedValue (ValueTree& tree, const Identifier& propertyID,
                 UndoManager* undoManager, const Type& defaultToUse);
 
    //==============================================================================
    operator Type() const noexcept                   { return cachedValue; }

    Type get() const noexcept                        { return cachedValue; }

    const Type& operator*() const noexcept           { return cachedValue; }

    const Type* operator->() const noexcept          { return &cachedValue; }

    template <typename OtherType>
    bool operator== (const OtherType& other) const
    {
        return cachedValue == other;
    }

    template <typename OtherType>
    bool operator!= (const OtherType& other) const   { return ! operator== (other); }
 
    //==============================================================================
    Value getPropertyAsValue();

    bool isUsingDefault() const;

    Type getDefault() const                          { return defaultValue; }
 
    //==============================================================================
    CachedValue& operator= (const Type& newValue);

    void setValue (const Type& newValue, UndoManager* undoManagerToUse);

    void resetToDefault();

    void resetToDefault (UndoManager* undoManagerToUse);

    void setDefault (const Type& value)                { defaultValue = value; }
 
    //==============================================================================
    void referTo (ValueTree& tree, const Identifier& property, UndoManager* um);

    void referTo (ValueTree& tree, const Identifier& property, UndoManager* um, const Type& defaultVal);

    void forceUpdateOfCachedValue();
 
    //==============================================================================
    ValueTree& getValueTree() noexcept                      { return targetTree; }

    const Identifier& getPropertyID() const noexcept        { return targetProperty; }

    UndoManager* getUndoManager() noexcept                  { return undoManager; }
 
private:
    //==============================================================================
    ValueTree targetTree;
    Identifier targetProperty;
    UndoManager* undoManager = nullptr;
    Type defaultValue;
    Type cachedValue;
 
    //==============================================================================
    void referToWithDefault (ValueTree&, const Identifier&, UndoManager*, const Type&);
    Type getTypedValue() const;
 
    void valueTreePropertyChanged (ValueTree& changedTree, const Identifier& changedProperty) override;
 
    //==============================================================================
    JUCE_DECLARE_WEAK_REFERENCEABLE (CachedValue)
    JUCE_DECLARE_NON_COPYABLE (CachedValue)
};
 
 
//==============================================================================
template <typename Type>
inline CachedValue<Type>::CachedValue() = default;
 
template <typename Type>
inline CachedValue<Type>::CachedValue (ValueTree& v, const Identifier& i, UndoManager* um)
    : targetTree (v), targetProperty (i), undoManager (um),
      defaultValue(), cachedValue (getTypedValue())
{
    targetTree.addListener (this);
}
 
template <typename Type>
inline CachedValue<Type>::CachedValue (ValueTree& v, const Identifier& i, UndoManager* um, const Type& defaultToUse)
    : targetTree (v), targetProperty (i), undoManager (um),
      defaultValue (defaultToUse), cachedValue (getTypedValue())
{
    targetTree.addListener (this);
}
 
template <typename Type>
inline Value CachedValue<Type>::getPropertyAsValue()
{
    return targetTree.getPropertyAsValue (targetProperty, undoManager);
}
 
template <typename Type>
inline bool CachedValue<Type>::isUsingDefault() const
{
    return ! targetTree.hasProperty (targetProperty);
}
 
template <typename Type>
inline CachedValue<Type>& CachedValue<Type>::operator= (const Type& newValue)
{
    setValue (newValue, undoManager);
    return *this;
}
 
template <typename Type>
inline void CachedValue<Type>::setValue (const Type& newValue, UndoManager* undoManagerToUse)
{
    if (! exactlyEqual (cachedValue, newValue) || isUsingDefault())
    {
        cachedValue = newValue;
        targetTree.setProperty (targetProperty, VariantConverter<Type>::toVar (newValue), undoManagerToUse);
    }
}
 
template <typename Type>
inline void CachedValue<Type>::resetToDefault()
{
    resetToDefault (undoManager);
}
 
template <typename Type>
inline void CachedValue<Type>::resetToDefault (UndoManager* undoManagerToUse)
{
    targetTree.removeProperty (targetProperty, undoManagerToUse);
    forceUpdateOfCachedValue();
}
 
template <typename Type>
inline void CachedValue<Type>::referTo (ValueTree& v, const Identifier& i, UndoManager* um)
{
    referToWithDefault (v, i, um, Type());
}
 
template <typename Type>
inline void CachedValue<Type>::referTo (ValueTree& v, const Identifier& i, UndoManager* um, const Type& defaultVal)
{
    referToWithDefault (v, i, um, defaultVal);
}
 
template <typename Type>
inline void CachedValue<Type>::forceUpdateOfCachedValue()
{
    cachedValue = getTypedValue();
}
 
template <typename Type>
inline void CachedValue<Type>::referToWithDefault (ValueTree& v, const Identifier& i, UndoManager* um, const Type& defaultVal)
{
    targetTree.removeListener (this);
    targetTree = v;
    targetProperty = i;
    undoManager = um;
    defaultValue = defaultVal;
    cachedValue = getTypedValue();
    targetTree.addListener (this);
}
 
template <typename Type>
inline Type CachedValue<Type>::getTypedValue() const
{
    if (const var* property = targetTree.getPropertyPointer (targetProperty))
        return VariantConverter<Type>::fromVar (*property);
 
    return defaultValue;
}
 
template <typename Type>
inline void CachedValue<Type>::valueTreePropertyChanged (ValueTree& changedTree, const Identifier& changedProperty)
{
    if (changedProperty == targetProperty && targetTree == changedTree)
        forceUpdateOfCachedValue();
}
 
} // namespace juce