Union.h

Go to the documentation of this file.

/****
 * ConfigDB/Union.h
 *
 * Copyright 2024 mikee47 <mike@sillyhouse.net>
 *
 * This file is part of the ConfigDB Library
 *
 * This library is free software: you can redistribute it and/or modify it under the terms of the
 * GNU General Public License as published by the Free Software Foundation, version 3 or later.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this library.
 * If not, see <https://www.gnu.org/licenses/>.
 *
 ****/
 
#pragma once
 
#include "Object.h"
 
namespace ConfigDB
{
class Union : public Object
{
public:
    using Tag = uint8_t;
 
    using Object::Object;
 
    Tag getTag() const
    {
        return getPropertyData(0)->uint8;
    }
 
    void setTag(Tag tag)
    {
        if(!writeCheck()) {
            return;
        }
        assert(tag < typeinfo().objectCount);
        disposeArrays();
        memset(getDataPtr(), 0, typeinfo().structSize);
        getPropertyData(0)->uint8 = tag;
        getObject(0).resetToDefaults();
    }
 
    void clear()
    {
        if(!writeCheck()) {
            return;
        }
        disposeArrays();
        memset(getDataPtr(), 0, typeinfo().structSize);
        getPropertyData(0)->uint8 = 0;
        getObject(0).clear();
    }
 
    unsigned getObjectCount() const
    {
        return 1;
    }
 
    Object getObject([[maybe_unused]] unsigned index)
    {
        assert(index == 0);
        return Object(*this, getTag());
    }
 
    unsigned getPropertyCount() const
    {
        return 0;
    }
 
    PropertyConst getProperty(unsigned) const
    {
        return {};
    }
 
    Property getProperty(unsigned)
    {
        return {};
    }
 
    template <typename Item> const Item as(Tag tag) const
    {
        assert(getTag() == tag);
        if(getTag() != tag) {
            return {};
        }
        return Item(*parent, typeinfo().getObject(tag), dataRef + propinfo().offset);
    }
 
    template <typename Item> Item as(Tag tag)
    {
        assert(getTag() == tag);
        if(getTag() != tag) {
            return {};
        }
        return Item(*parent, typeinfo().getObject(tag), dataRef + propinfo().offset);
    }
 
    template <typename Item> Item to(Tag tag)
    {
        setTag(tag);
        return Item(*parent, typeinfo().getObject(tag), dataRef + propinfo().offset);
    }
};
 
template <class ClassType> class UnionTemplate : public Union
{
public:
    using Union::Union;
};
 
template <class UpdaterType, class ClassType> class UnionUpdaterTemplate : public ClassType
{
public:
    using ClassType::ClassType;
 
    explicit operator bool() const
    {
        return Object::operator bool() && this->isWriteable();
    }
};
 
} // namespace ConfigDB