ObjectStreamIn.h

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// Jolt Physics Library (https://github.com/jrouwe/JoltPhysics)
// SPDX-FileCopyrightText: 2021 Jorrit Rouwe
// SPDX-License-Identifier: MIT
 
#pragma once
 
#include <Jolt/ObjectStream/ObjectStream.h>
#include <Jolt/Core/Reference.h>
#include <Jolt/Core/RTTI.h>
#include <Jolt/Core/UnorderedMap.h>
 
JPH_SUPPRESS_WARNINGS_STD_BEGIN
#include <fstream>
JPH_SUPPRESS_WARNINGS_STD_END
 
JPH_NAMESPACE_BEGIN
 
class ObjectStreamIn : public IObjectStreamIn
{
private:
    struct ClassDescription;
 
public:
    template <class T> 
    static bool sReadObject(istream &inStream, T *&outObject)
    {
        // Create the input stream
        bool result = false;
        ObjectStreamIn *stream = ObjectStreamIn::Open(inStream);
        if (stream) 
        {
            // Read the object
            outObject = (T *)stream->Read(JPH_RTTI(T));
            result = (outObject != nullptr);
            delete stream;
        }
        return result;
    }
 
    template <class T> 
    static bool sReadObject(istream &inStream, Ref<T> &outObject)
    {
        T *object = nullptr;
        bool result = sReadObject(inStream, object);
        outObject = object;
        return result;
    }
 
    template <class T>
    static bool sReadObject(const char *inFileName, T *&outObject)
    {
        std::ifstream stream;
        stream.open(inFileName, std::ifstream::in | std::ifstream::binary);
        if (!stream.is_open()) 
            return false;
        return sReadObject(stream, outObject);
    }
 
    template <class T>
    static bool sReadObject(const char *inFileName, Ref<T> &outObject)
    {
        T *object = nullptr;
        bool result = sReadObject(inFileName, object);
        outObject = object;
        return result;
    }
 
    // EVERYTHING BELOW THIS SHOULD NOT DIRECTLY BE CALLED
 
    void *                      Read(const RTTI *inRTTI);
    void *                      ReadObject(const RTTI *& outRTTI);
    bool                        ReadRTTI();
    virtual bool                ReadClassData(const char *inClassName, void *inInstance) override;
    bool                        ReadClassData(const ClassDescription &inClassDesc, void *inInstance);
    virtual bool                ReadPointerData(const RTTI *inRTTI, void **inPointer, int inRefCountOffset = -1) override;
    bool                        SkipAttributeData(int inArrayDepth, EOSDataType inDataType, const char *inClassName);
 
protected:
    explicit                    ObjectStreamIn(istream &inStream);
 
    static bool                 GetInfo(istream &inStream, EStreamType &outType, int &outVersion, int &outRevision);
 
    static ObjectStreamIn *     Open(istream &inStream);
 
    istream &                   mStream;
 
private:
    struct AttributeDescription
    {
        int                     mArrayDepth = 0;
        EOSDataType             mSourceType = EOSDataType::Invalid;
        EOSDataType             mDestinationType = EOSDataType::Invalid;
        String                  mClassName;
        int                     mIndex = -1;
    };
 
    struct ClassDescription
    {
                                ClassDescription() = default;
        explicit                ClassDescription(const RTTI *inRTTI)                    : mRTTI(inRTTI) { }
 
        const RTTI *            mRTTI = nullptr;
        Array<AttributeDescription> mAttributes;
    };
    
    struct ObjectInfo
    {
                                ObjectInfo() = default;
                                ObjectInfo(void *inInstance, const RTTI *inRTTI)        : mInstance(inInstance), mRTTI(inRTTI) { }
 
        void *                  mInstance = nullptr;
        const RTTI *            mRTTI = nullptr;
    };
 
    struct Link
    {
        void **                 mPointer;
        int                     mRefCountOffset;
        Identifier              mIdentifier;
        const RTTI *            mRTTI;
    };
    
    using IdentifierMap = UnorderedMap<Identifier, ObjectInfo>;
    using ClassDescriptionMap = UnorderedMap<String, ClassDescription>;
 
    ClassDescriptionMap         mClassDescriptionMap;
    IdentifierMap               mIdentifierMap;                                         
    Array<Link>                 mUnresolvedLinks;                                       
};
 
JPH_NAMESPACE_END