138 lines
2.7 KiB
C++
138 lines
2.7 KiB
C++
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///////////////////////////////////////////////////////////////////////////////
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//
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// Copyright (c) 1998, Microsoft Corp. All rights reserved.
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//
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// FILE
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//
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// dsenum.cpp
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//
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// SYNOPSIS
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//
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// This file defines the class DBEnumerator.
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//
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// MODIFICATION HISTORY
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//
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// 02/20/1998 Original version.
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// 04/15/1998 Initialize refCount to zero in constructor.
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//
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///////////////////////////////////////////////////////////////////////////////
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#include <ias.h>
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#include <iasutil.h>
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#include <dsenum.h>
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DBEnumerator::DBEnumerator(DBObject* container, IRowset* members)
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: refCount(0),
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parent(container),
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items(members),
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readAccess(createReadAccessor(members))
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{ }
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STDMETHODIMP_(ULONG) DBEnumerator::AddRef()
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{
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return InterlockedIncrement(&refCount);
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}
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STDMETHODIMP_(ULONG) DBEnumerator::Release()
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{
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LONG l = InterlockedDecrement(&refCount);
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if (l == 0) { delete this; }
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return l;
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}
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STDMETHODIMP DBEnumerator::QueryInterface(const IID& iid, void** ppv)
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{
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if (iid == __uuidof(IUnknown))
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{
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*ppv = static_cast<IUnknown*>(this);
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}
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else if (iid == __uuidof(IEnumVARIANT))
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{
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*ppv = static_cast<IEnumVARIANT*>(this);
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}
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else
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{
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return E_NOINTERFACE;
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}
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InterlockedIncrement(&refCount);
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return S_OK;
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}
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STDMETHODIMP DBEnumerator::Next(ULONG celt,
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VARIANT* rgVar,
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ULONG* pCeltFetched)
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{
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if (rgVar == NULL) { return E_INVALIDARG; }
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//////////
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// Initialize the out parameters.
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//////////
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if (pCeltFetched != NULL) { *pCeltFetched = celt; }
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for (ULONG i=0; i<celt; ++i) { VariantInit(rgVar + i); }
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try
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{
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//////////
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// Move through the items at most 'celt' times.
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//////////
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while (celt && items.moveNext())
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{
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// Get the row data.
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items.getData(readAccess, this);
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// Never return the root from an enumerator.
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if (identity == 1) { continue; }
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// Create an object.
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V_DISPATCH(rgVar) = parent->spawn(identity, name);
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V_VT(rgVar) = VT_DISPATCH;
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// Update the state.
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--celt;
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++rgVar;
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}
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}
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catch (...)
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{ }
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// Subtract off any elements that weren't fetched.
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if (pCeltFetched) { *pCeltFetched -= celt; }
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return celt ? S_FALSE : S_OK;
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}
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STDMETHODIMP DBEnumerator::Skip(ULONG celt)
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{
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try
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{
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while (celt && items.moveNext()) { --celt; }
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}
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CATCH_AND_RETURN()
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return celt ? S_FALSE : S_OK;
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}
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STDMETHODIMP DBEnumerator::Reset()
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{
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try
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{
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items.reset();
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}
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CATCH_AND_RETURN()
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return S_OK;
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}
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STDMETHODIMP DBEnumerator::Clone(IEnumVARIANT** ppEnum)
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{
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return E_NOTIMPL;
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}
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