This example shows how to handle XML vocabularies with polymorphic document
root elements in the Embedded C++/Hybrid mapping. For general coverage of
XML Schema polymorphism handling see the polymorphism example.

The example consists of the following files:

supermen.xsd
  XML Schema which describes supermen instance documents.

person.xml
superman.xml
batman.xml
  Sample XML instance documents.

supermen.hxx
supermen.cxx

supermen-pskel.hxx
supermen-pskel.cxx
supermen-pimpl.hxx
supermen-pimpl.cxx

supermen-pskel.hxx
supermen-pskel.cxx
supermen-pimpl.hxx
supermen-pimpl.cxx
  Object model (the first pair of files), parser skeletons (the
  second pair), parser implementations (the third pair), serializer
  skeletons (the fourth pair), and serializer implementations (the
  fifth pair). These files are generated by the XSD/e compiler from
  supermen.xsd. The --generate-parser, --generate-serializer, and 
  --generate-aggregate options were used to request the generation
  of the parsing and serialization code. The --generate-polymorphic
  option was used to request the generation of the polymorphism-aware
  code. Since our vocabulary uses substitution groups, the XSD/e
  compiler is able to automatically determine which type hierarchy is
  polymorphic (otherwise we would have had to use the --polymorphic-type
  option). The --generate-typeinfo option was used to request the 
  generation of custom type information for polymorphic object model
  types. Finally, the --root-element option was used to specify the
  document root element.

driver.cxx
  Driver for the example. It first calls the parser that constructs
  the object model from the input XML file. It then prints the content
  of the object model to STDERR at which point it determines the actual
  (dynamic) types of polymorphic objects. Finally, the driver calls the
  serializer to serialize the object model back to XML.

To run the example on the sample XML instance documents simply execute:

$ ./driver person.xml
$ ./driver superman.xml
$ ./driver batman.xml

The example reads from STDIN if input file is not specified:

$ ./driver <person.xml
$ ./driver <superman.xml
$ ./driver <batman.xml
