AOO410/main/sal/inc/systools/win32/comtools.hxx

/**************************************************************
 * 
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 * 
 *************************************************************/



#pragma once

#include <string>
#include <stdexcept>
#if defined _MSC_VER
#pragma warning(push,1)
#endif
#include <objbase.h>
#if defined _MSC_VER
#pragma warning(pop)
#endif

namespace sal
{
namespace systools
{
    typedef int HRESULT;
    
    /* Simple exception class for propagating COM errors */
    class ComError : public std::runtime_error
    {
    public:
        ComError(const std::string& message, HRESULT hr) :
            std::runtime_error(message),
            hr_(hr)
        {}
        
        HRESULT GetHresult() const
        {
            return hr_;
        }
        
    private:                
        HRESULT hr_;
    };
               
    /* A simple COM smart pointer template */
    template <typename T>
    class COMReference
    {
    public:
        COMReference() :            
            com_ptr_(NULL)
        {
        }
                    
        explicit COMReference(T* comptr) :
            com_ptr_(comptr)
        {   
            addRef();         
        }
        
        /* Explicitly controllable whether AddRef will be called or not */
        COMReference(T* comptr, bool bAddRef) :
            com_ptr_(comptr)
        {
            if (bAddRef)
                addRef();
        }    
          
        COMReference(const COMReference<T>& other) :
            com_ptr_(other.com_ptr_)
        {
            addRef();
        }
        
        COMReference<T>& operator=(const COMReference<T>& other)
        {
            if (other.com_ptr_)
                other.com_ptr_->AddRef();
            release();
            com_ptr_ = other.com_ptr_;
            return *this;                
        }
                        
        COMReference<T>& operator=(T* comptr)
        {
            release();                
            com_ptr_ = comptr;            
            addRef();
            return *this;
        }
        
        ~COMReference()
        {     
            release();                      
        }
        
        template<typename InterfaceType>                
        COMReference<InterfaceType> QueryInterface(REFIID iid)
        {
            COMReference<InterfaceType> ip;
            HRESULT hr = E_FAIL;            
            if (com_ptr_)
                hr = com_ptr_->QueryInterface(iid, reinterpret_cast<LPVOID*>(&ip));
            
            if (FAILED(hr))
                throw ComError("QueryInterface failed: Interface not supported!", hr);                
                
            return ip;                
        }
                        
        T* operator->() const
        {
            return com_ptr_;
        }
        
        T& operator*() const
        {
            return *com_ptr_;
        }
        
        /* Necessary for assigning com_ptr_ from functions like
           CoCreateInstance which require a 'void**' */                
        T** operator&()
        {
            release();
            com_ptr_ = NULL;
            return &com_ptr_;
        }
        
        T* get() const
        {
            return com_ptr_;
        }
    
        COMReference<T>& clear()
        {
            release();
            com_ptr_ = NULL;
            return *this;
        }
        
        bool is() const
        {
            return (com_ptr_ != NULL);
        }
        
    private:
        ULONG addRef()
        {            
            ULONG cnt = 0;
            if (com_ptr_)
                cnt = com_ptr_->AddRef();
            return cnt;                
        }
        
        ULONG release()
        {                        
            ULONG cnt = 0;
            if (com_ptr_)
                cnt = com_ptr_->Release();
            return cnt;                
        }
                            
    private:
        T* com_ptr_;                        
    };
            
} // systools
} // sal

/* Typedefs for some popular COM interfaces */
typedef sal::systools::COMReference<IDataObject> IDataObjectPtr;
typedef sal::systools::COMReference<IStream> IStreamPtr;
typedef sal::systools::COMReference<IEnumFORMATETC> IEnumFORMATETCPtr;