RscReadEnumerator.hxx

 
//
//  Copyright Phoenix Contact GmbH & Co. KG
//
#pragma once
#include "Arp/Base/Core/Arp.hpp"
#include "Arp/Base/Rsc/Commons/Rsc.hpp"
#include "Arp/Base/Rsc/Commons/RscArrayReader.hpp"
#include "Arp/Base/Rsc/Commons/IRscReadEnumerator.hxx"
#include "Arp/Base/Rsc/Commons/Services/RscReader.hpp"
 
namespace Arp::Base::Rsc::Commons::Services
{
 
template<class T>
class RscReadEnumerator : public IRscReadEnumerator<T>
{
public: // construction
    RscReadEnumerator(RscReader& rscReader, bool isArrayEnumerator);
 
    // canonical construction/assignment/destruction
    RscReadEnumerator(const RscReadEnumerator& arg);
    RscReadEnumerator(RscReadEnumerator&& arg)noexcept;
    RscReadEnumerator& operator=(const RscReadEnumerator& arg);
    RscReadEnumerator& operator=(RscReadEnumerator&& arg)noexcept;
    ~RscReadEnumerator(void)override;
 
public: // operations of IRscReadEnumerator
    size_t  BeginRead(void)override;
    bool    ReadNext(T& current)override;
    bool    ReadNext(RscArrayReader& current)override;
    void    EndRead(void)override;
 
private: // fields
    RscReader&  rscReader;
    size_t      arrayLength = UndefinedArrayLength;
    bool        isArrayEnumerator;
    bool        hasEnded = false;
    RscType     rscType = RscTypeDeduction().Get<T>();
    size_t      fieldCount = StructInfo<T>().FieldCount;
    bool        isConcreteType = RscTypeInfo::IsConcreteType(this->rscType);
 
public: // static fields
    static constexpr size_t UndefinedArrayLength = std::numeric_limits<size_t>::max();
};
 
// inline methods of class RscEnumerator
 
template<class T>
inline RscReadEnumerator<T>::RscReadEnumerator(const RscReadEnumerator& arg) = default;
 
template<class T>
inline RscReadEnumerator<T>::RscReadEnumerator(RscReadEnumerator&& arg)noexcept = default;
 
template<class T>
inline RscReadEnumerator<T>& RscReadEnumerator<T>::operator=(const RscReadEnumerator& arg) = default;
 
template<class T>
inline RscReadEnumerator<T>& RscReadEnumerator<T>::operator=(RscReadEnumerator&& arg)noexcept = default;
 
template<class T>
inline RscReadEnumerator<T>::~RscReadEnumerator() = default;
 
template<class T>
inline RscReadEnumerator<T>::RscReadEnumerator(RscReader& rscReader, bool isArrayEnumerator)
    : rscReader(rscReader)
    , isArrayEnumerator(isArrayEnumerator)
{
}
 
template<class T>
inline size_t RscReadEnumerator<T>::BeginRead()
{
    if(this->isArrayEnumerator)
    {
        this->rscReader.ReadTag(RscType::Array);
        if(this->rscType == RscType::Struct)
        {
            this->rscReader.ReadBeginStruct(this->fieldCount);
        }
        else
        {
            this->rscReader.ReadTag(this->rscType);
        }
        this->arrayLength = this->rscReader.ReadArrayLength();
    }
    else // use standard enumerator
    {
        this->rscReader.ReadTag(RscType::Enumerator);
    }
    return this->arrayLength;
}
 
template<class T>
inline bool RscReadEnumerator<T>::ReadNext(T& current)
{
    if(this->isArrayEnumerator)
    {
        if(this->arrayLength == 0)
        {
            return false;    // end of array reached
        }
        // else
        --this->arrayLength;
        this->rscReader.Read(current, this->isConcreteType); // omit tag if element type is not object
    }
    else // use standard enumerator
    {
        if(this->hasEnded)
        {
            return false;
        }
        this->rscReader.ReadEnumeratorTag(this->rscType, this->hasEnded);
        if(this->hasEnded)
        {
            return false; // end of sequence
        }
        if(this->rscType == RscType::Struct)
        {
            size_t readFieldCount = this->rscReader.ReadFieldCount();
            if(readFieldCount != this->fieldCount)
            {
                throw RscException(
                    RscError::ProtocolViolation,
                    "Read invalid struct field count: expected '{}', received '{}'",
                    this->fieldCount, readFieldCount);
            }
        }
        this->rscReader.Read(current, true);
    }
    return true;
}
 
template<class T>
inline bool RscReadEnumerator<T>::ReadNext(RscArrayReader& current)
{
    if (this->arrayLength == 0)
    {
        return false;    // end of array reached
    }
    // else
    this->rscReader.ReadTag(RscType::Array);
    RscType elementType = this->rscReader.ReadTag();
    size_t arraySize = this->rscReader.ReadArrayLength();
    current = RscArrayReader(arraySize, elementType, this->rscReader);
    return true;
}
 
template<class T>
inline void RscReadEnumerator<T>::EndRead()
{
    if(this->isArrayEnumerator)
    {
        if(this->arrayLength != 0)
        {
            throw InvalidOperationException("End of array enumerator was not reached yet");
        }
        // else
        this->hasEnded = true;
    }
    // else standard enumeration was read
}
 
} // end of namespace Arp::Base::Rsc::Commons::Services