CoreTransactionItem.h

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#ifndef MGA_CORETRANSACTIONITEM_H
#define MGA_CORETRANSACTIONITEM_H

// --------------------------- CCoreTransactionItem

// IMPORTANT: Each transaction item cares only about itself and those
// of its parts which are not transaction items themselves.
// Never make any modification to other transaction items during
// abort, discard, commit or commit finish.

// call CCoreProject::RegisterTransactionItem to get into the
// latest nested transaction, be dirty when registering

class ATL_NO_VTABLE CCoreTransactionItem
{
public:
        // dirty if modified in the latest transaction
        virtual bool IsDirty() const NOTHROW = 0;

        // we clear the flag at the beggining of a nested transaction
        // we set it at abort, or committing a nested tr and gaining focus
        virtual void ChangeDirty(bool dirty) NOTHROW = 0;

        // must be dirty, discard the latest transaction value, clear dirty
        virtual void AbortNestedTransaction() NOTHROW = 0;

        // must be dirty, discard the previous transaction value, keep dirty
        // called only for nested transactions when we merge the latest two values
        virtual void DiscardPreviousValue() NOTHROW = 0;
};

// --------------------------- CCoreFinalTrItem

// call CCoreProject::RegisterFinalTrItem to register, call it only once
// CoreObjects register to group database access of their CoreAttributes

class ATL_NO_VTABLE CCoreFinalTrItem : public ISupportErrorInfo // all subclasses will inherit ISupportErrorInfoImpl, so inherit here to save a vtable entry
{
public:
        // called for final abort, clear dirty
        virtual void AbortFinalTransaction() NOTHROW = 0;

        // should do the work, may be called several times,
        virtual void CommitFinalTransaction() = 0;

        // clean up, clear dirty
        virtual void CommitFinalTransactionFinish(bool undo) NOTHROW = 0;
};

template<const IID* piid>
class ATL_NO_VTABLE CCoreFinalTrItemImpl : public CCoreFinalTrItem // all subclasses will inherit ISupportErrorInfoImpl, so inherit here to save a vtable entry
{
        // ISupportErrorInfoImpl
public:
        STDMETHOD(InterfaceSupportsErrorInfo)(_In_ REFIID riid)
        {
                return (InlineIsEqualGUID(riid,*piid)) ? S_OK : S_FALSE;
        }

};

// --------------------------- CCoreUndoItem

// call CCoreProject::RegisterUndoItem to register,
// call it only from CommitFinalTransactionFinish

class ATL_NO_VTABLE CCoreUndoItem : public CCoreTransactionItem
        // KMS: inherit from CCoreTransactionItem so one less vtable pointer is required in subclasses
        // (the only subclass is CCoreDataAttribute which also implements CCoreTransactionItem)
{
public:
        // do the work here, called only once for each level
        // this is not a regular transaction, do not register new
        // transaction items and final transaction items
        virtual void UndoTransaction() = 0;
        virtual void UndoTransactionFinish() NOTHROW = 0;

        virtual void RedoTransaction() = 0;
        virtual void RedoTransactionFinish() NOTHROW = 0;

        // not a regular transaction, only locking attributes can register
        virtual void DiscardLastItem() = 0;
        virtual void DiscardLastItemFinish() NOTHROW = 0;
        virtual void DiscardLastItemCancel() NOTHROW = 0;
};

#endif//MGA_CORETRANSACTIONITEM_H