Keep only base/extractor.[cc|h].

base/dual_interface_switch.h

-// Copyright 2009 Google Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-// ========================================================================
-
-// This class allows for implementing two dual interfaces, ReadOnly being a
-// read-only dual interface, and ReadWrite being a read-write dual interface.
-// Based on the value returned from is_read_only(), the ReadOnly or the
-// ReadWrite dual interface is exposed at runtime.
-//
-// An ATL class needs to
-// (a) derive from DualInterfaceSwitch
-//
-// (b) implement the is_read_only() method. For instance:
-//   bool is_read_only() { return is_read_only_; }
-//
-// (c) add entries similar to below for the dual interfaces as well as IDispatch
-//     to the COM map:
-//  BEGIN_COM_MAP(AppData)
-//    COM_INTERFACE_ENTRY2(IUnknown, IAppData)
-//    COM_INTERFACE_ENTRY_FUNC(__uuidof(IAppDataReadOnly), 0, DualInterfaceQI)
-//    COM_INTERFACE_ENTRY_FUNC(__uuidof(IAppData), 0, DualInterfaceQI)
-//    COM_INTERFACE_ENTRY_FUNC(__uuidof(IDispatch), 0, DualInterfaceQI)
-//  END_COM_MAP()
-
-#ifndef OMAHA_BASE_DUAL_INTERFACE_SWITCH_H_
-#define OMAHA_BASE_DUAL_INTERFACE_SWITCH_H_
-
-#include <windows.h>
-#include <atlbase.h>
-#include "base/basictypes.h"
-#include "omaha/base/debug.h"
-
-namespace omaha {
-
-template <class T, class ReadOnly, REFIID iid_read_only,
-          class ReadWrite, REFIID iid_read_write>
-class ATL_NO_VTABLE DualInterfaceSwitch : public ReadOnly,
-                                          public ReadWrite {
- protected:
-  // DualInterfaceQI gives out either the ReadOnly or ReadWrite interface
-  // pointer, based on the value of is_read_only() that class T implements.
-  // The signature of this function has to be
-  //   HRESULT WINAPI func(void* pv, REFIID riid, LPVOID* ppv, DWORD dw);
-  // for it to work with COM_INTERFACE_ENTRY_FUNC.
-  static HRESULT WINAPI DualInterfaceQI(void* p,
-                                        REFIID riid,
-                                        LPVOID* v,
-                                        DWORD) {
-    // Ensure that ReadOnly and ReadWrite are derived from IDispatch.
-    ASSERT1(static_cast<IDispatch*>(reinterpret_cast<ReadOnly*>(1)));
-    ASSERT1(static_cast<IDispatch*>(reinterpret_cast<ReadWrite*>(1)));
-
-    if (riid != iid_read_only &&
-        riid != iid_read_write &&
-        riid != __uuidof(IDispatch)) {
-      // Returning S_FALSE allows COM map processing to continue. Another entry
-      // in the COM map might match the interface requested.
-      return S_FALSE;
-    }
-
-    T* t = reinterpret_cast<T*>(p);
-    if (t->is_read_only() && riid == iid_read_write) {
-      return S_FALSE;
-    }
-
-    t->AddRef();
-    if (t->is_read_only() || riid == iid_read_only) {
-      *v = static_cast<ReadOnly*>(t);
-      return S_OK;
-    }
-
-    *v = static_cast<ReadWrite*>(t);
-    return S_OK;
-  }
-};
-
-}  // namespace omaha
-
-#endif  // OMAHA_BASE_DUAL_INTERFACE_SWITCH_H_