How to load XML document from `std::istream`?

I'd like to load TinyXml documents from std::istream, but it doesn't contain such method:

/** Load a file using the current document value.
    Returns true if successful. Will delete any existing
    document data before loading.
*/
bool LoadFile( TiXmlEncoding encoding = TIXML_DEFAULT_ENCODING );
/// Save a file using the current document value. Returns true if successful.
bool SaveFile() const;
/// Load a file using the given filename. Returns true if successful.
bool LoadFile( const char * filename, TiXmlEncoding encoding = TIXML_DEFAULT_ENCODING );
/// Save a file using the given filename. Returns true if successful.
bool SaveFile( const char * filename ) const;
/** Load a file using the given FILE*. Returns true if successful. Note that this method
    doesn't stream - the entire object pointed at by the FILE*
    will be interpreted as an XML file. TinyXML doesn't stream in XML from the current
    file location. Streaming may be added in the future.
*/
bool LoadFile( FILE*, TiXmlEncoding encoding = TIXML_DEFAULT_ENCODING );

I see that it contains function that uses FILE, is it possible to convert std::istream to FILE?

Solution

I've found clear solution here:

C++ style input:

based on std::istream

operator>>

Reads XML from a stream, making it useful for network transmission. The tricky part is knowing when the XML document is complete, since there will almost certainly be other data in the stream. TinyXML will assume the XML data is complete after it reads the root element. Put another way, documents that are ill-constructed with more than one root element will not read correctly. Also note that operator>> is somewhat slower than Parse, due to both implementation of the STL and limitations of TinyXML.

Example:

std::istream *in = ResourceManager::getInstance().getResource(resourceName);
if(in) {
   TiXmlDocument doc;
   // load document from resource stream
   *in >> doc;
}