Because many of the data structures used and returned by PyGgy and
PyLly are complex, PyGgy provides hooks to visualize them using
the AT&T GraphViz program dotty. If you do not have
the GraphViz program, you will still be able to use the PyGgy package
but you may not be able to access all the debugging information.
GraphViz is available free of charge at http://www.research.att.com/sw/tools/graphviz/.
To use graphviz with PyGgy, make sure that dotty is in your path,
and invoke PyGgy or PyLly with a high debug value (for example,
specifying debug=3
as an argument to getlexer
or
getparser
) or use the function pyggy.glr.dottree
to
display trees returned from the parse
method.
See the PyGgy Home Page.