library/cpp/protobuf/util/merge.cpp


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#include "merge.h"
#include "simple_reflection.h"

#include <google/protobuf/message.h>

#include <library/cpp/protobuf/util/proto/merge.pb.h>

namespace NProtoBuf {
    void RewriteMerge(const Message& src, Message& dst) { 
        const Descriptor* d = src.GetDescriptor(); 
        Y_ASSERT(d == dst.GetDescriptor()); 

        for (int i = 0; i < d->field_count(); ++i) { 
            if (TConstField(src, d->field(i)).Has()) 
                TMutableField(dst, d->field(i)).Clear(); 
        } 

        dst.MergeFrom(src); 
    }

    static void ClearNonMergeable(const Message& src, Message& dst) { 
        const Descriptor* d = src.GetDescriptor(); 
        if (d->options().GetExtension(DontMerge)) { 
            dst.Clear(); 
            return; 
        } 

        for (int i = 0; i < d->field_count(); ++i) { 
            const FieldDescriptor* fd = d->field(i); 
            TConstField srcField(src, fd); 
            if (srcField.Has()) { 
                TMutableField dstField(dst, fd); 
                if (fd->options().GetExtension(DontMergeField)) 
                    dstField.Clear(); 
                else if (!fd->is_repeated() && dstField.IsMessage() && dstField.Has()) 
                    ClearNonMergeable(*srcField.Get<const Message*>(), *dstField.MutableMessage()); 
            } 
        } 
    }

    void CustomMerge(const Message& src, Message& dst) { 
        ClearNonMergeable(src, dst); 
        dst.MergeFrom(src); 
    }

}