Optional.h

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/*
 * Copyright Onix Solutions Limited [OnixS]. All rights reserved.
 *
 * This software owned by Onix Solutions Limited [OnixS] and is protected by
 * copyright law and international copyright treaties.
 *
 * Access to and use of the software is governed by the terms of the applicable
 * ONIXS Software Services Agreement (the Agreement) and Customer end user
 * license agreements granting a non-assignable, non-transferable and
 * non-exclusive license to use the software for it's own data processing
 * purposes under the terms defined in the Agreement.
 *
 * Except as otherwise granted within the terms of the Agreement, copying or
 * reproduction of any part of this source code or associated reference material
 * to any other location for further reproduction or redistribution, and any
 * amendments to this copyright notice, are expressly prohibited.
 *
 * Any reproduction or redistribution for sale or hiring of the Software not in
 * accordance with the terms of the Agreement is a violation of copyright law.
 */
 
#pragma once
 
#include <OnixS/Senaf/MarketData/Export.h>
 
#include <new>
 
namespace OnixS { namespace Senaf { namespace MarketData {
 
template <typename T>
class Optional
{
public:
    Optional()
      : init_(false)
    {
    }

    Optional(const T& val)
      : init_(true)
    {
        construct(val);
    }

    Optional(const Optional<T>& opt)
      : init_(opt.init_)
    {
        if (init_)
        {
            construct(opt.get());
        }
    }

    Optional& operator=(const Optional<T>& opt)
    {
        destruct();
 
        if ((init_ = opt.init_))
        {
            construct(opt.get());
        }
 
        return *this;
    }

    Optional& operator=(const T& val)
    {
        destruct();
 
        init_ = true;
 
        construct(val);
 
        return *this;
    }

    ~Optional()
    {
        destruct();
    }

    operator bool() const
    {
        return init_;
    }

    T& operator*()
    {
        return get(); // undefined if not initialized
    }

    const T& operator*() const
    {
        return get(); // undefined if not initialized
    }

    T& value()
    {
        return **this;
    }

    const T& value() const
    {
        return **this;
    }

    void reset()
    {
        destruct();
 
        init_ = false;
    }
 
protected:
    void* storage()
    {
        return data_;
    }
 
    const void* storage() const
    {
        return data_;
    }
 
    T& get()
    {
        return *static_cast<T*>(storage());
    }
 
    const T& get() const
    {
        return *static_cast<const T*>(storage());
    }
 
    void destruct()
    {
        if (init_)
        {
            get().~T();
        }
        init_ = false;
    }
 
    void construct(const T& data)
    {
        new(storage()) T(data);
    }
 
    char data_[sizeof(T)];
    bool init_;
};
 
}}} // namespace OnixS::Senaf::MarketData