This example shows how to use the optional wildcard mapping provided
by C++/Tree to parse, access, modify, and serialize the XML data
matched by XML Schema wildcards (any and anyAttribute). For an
alternative approach that employes type customization see the
custom/wildcard example.

The example consists of the following files:

email.xsd
  XML Schema which describes a simple email format with the
  extensible envelope type.

email.xml
  Sample email message.

email.hxx
email.ixx
email.cxx
  C++ types that represent the given vocabulary, a set of parsing
  functions that convert XML instance documents to a tree-like in-memory
  object model, and a set of serialization functions that convert the
  object model back to XML.

  These files are generated by the XSD compiler from email.xsd using the
  following command line:

  xsd cxx-tree --generate-wildcard --generate-serialization \
      --root-element message email.xsd

  Note that the --generate-wildcard option is used to request the
  wildcard mapping.

driver.cxx
  Driver for the example. It first calls one of the parsing functions
  that constructs the object model from the input file. It then prints
  the content of the object model to STDERR. Next the driver creates a
  reply email which is then serialized to XML.

To compile and link the example manually from the command line we can use
the following commands (replace 'c++' with your C++ compiler name):

c++ -DXSD_CXX11 -c email.cxx
c++ -DXSD_CXX11 -c driver.cxx
c++ -o driver driver.o email.o -lxerces-c

Note that we need to define the XSD_CXX11 preprocessor macro since the
source code includes libxsd headers directly.

To run the example on the sample XML instance document execute:

./driver email.xml