ObjectBase.hpp

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/****
 * ObjectBase.hpp - POD base class type for defining data structures
 *
 * Copyright 2019 mikee47 <mike@sillyhouse.net>
 *
 * This file is part of the FlashString 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/>.
 *
 * @author: Nov 2019 - Mikee47 <mike@sillyhouse.net>
 *
 ****/
 
#pragma once
 
#include "config.hpp"
 
namespace FSTR
{
class ObjectBase
{
public:
    FSTR_NOINLINE constexpr const size_t length() const
    {
        if(isNull()) {
            return 0;
        }
        if(isCopy()) {
            return reinterpret_cast<const ObjectBase*>(flashLength_ & ~copyBit)->length();
        }
        return flashLength_;
    }
 
    FSTR_INLINE constexpr const size_t size() const
    {
        return ALIGNUP4(length());
    }
 
    bool operator==(const ObjectBase& other) const;
 
    template <class ObjectType> FSTR_INLINE constexpr const ObjectType& as() const
    {
        return *static_cast<const ObjectType*>(this);
    }
 
    const uint8_t* data() const;
 
    size_t read(size_t offset, void* buffer, size_t count) const;
 
    size_t readFlash(size_t offset, void* buffer, size_t count) const;
 
    FSTR_INLINE constexpr const bool isCopy() const
    {
        return (flashLength_ & copyBit) != 0;
    }
 
    FSTR_INLINE constexpr const bool isNull() const
    {
        return flashLength_ == lengthInvalid;
    }
 
    /* Member data must be public for initialisation to work but DO NOT ACCESS DIRECTLY !! */
 
    const uint32_t flashLength_;
    // const uint8_t data[]
 
protected:
    static const ObjectBase empty_;
    static constexpr uint32_t copyBit = 0x80000000U;       
    static constexpr uint32_t lengthInvalid = copyBit | 0; 
};
 
} // namespace FSTR