    """Utility class for keeping track of the context.

    A utility class that holds information about the file we are parsing
    and the environment we are doing it in.

    (c) Copyright by Jay Love, 2000 (mailto:jsliv@jslove.org)

    Permission to use, copy, modify, and distribute this software and its
    documentation for any purpose and without fee or royalty is hereby granted,
    provided that the above copyright notice appear in all copies and that
    both that copyright notice and this permission notice appear in
    supporting documentation or portions thereof, including modifications,
    that you make.

    This software is based in part on work done by the Jakarta group.

    """

    import os

    class PSPContext(object):
        """PSPContext is an abstract base class for Context classes.

        Holds all the common stuff that various parts of the compilation
        will need access to. The items in this class will be used by both
        the compiler and the class generator.

        """

        def getClassPath(self):
            raise NotImplementedError

        def getReader(self):
            raise NotImplementedError

        def getWriter(self):
            raise NotImplementedError

        def getOutputDirectory(self):
            """Provide directory to dump PSP source file to."""
            raise NotImplementedError

        def getServletClassName(self):
            """Return the class name of the servlet being generated."""
            raise NotImplementedError

        def getFullClassName(self):
            """Return the class name including package prefixes.

            Won't use this for now.

            """
            raise NotImplementedError

        def getPythonFileName(self):
            """Return the filename that we are generating to."""
            raise NotImplementedError

        def getPythonFileEncoding(self):
            """Return the encoding of the file that we are generating."""
            raise NotImplementedError

        def setPSPReader(self, reader):
            """Set the PSPReader for this context."""
            raise NotImplementedError

        def setServletWriter(self, writer):
            """Set the PSPWriter instance for this context."""
            raise NotImplementedError

        def setPythonFileName(self, name):
            """Set the name of the .py file to generate."""
            raise NotImplementedError

        def setPythonFileEncoding(self, encoding):
            """Set the encoding of the .py file to generate."""
            raise NotImplementedError

    class PSPCLContext(PSPContext):
        """A context for command line compilation.

        Currently used for both command line and PSPServletEngine compilation.
        This class provides all the information necessary during the parsing
        and page generation steps of the PSP compilation process.

        """

        def __init__(self, pspfile):
            PSPContext.__init__(self)
            self._baseUri, self._pspfile = os.path.split(pspfile)
            self._fullpath = pspfile
            self._pyFileEncoding = None

        def getClassPath(self):
            raise NotImplementedError

        def getReader(self):
            """Return the PSPReader object assigned to this context."""
            return self._pspReader

        def getServletWriter(self):
            """Return the ServletWriter object assigned to this context."""
            return self._servletWriter

        def getOutputDirectory(self):
            """Provide directory to dump PSP source file to.

            I am probably doing this in reverse order at the moment.
            I should start with this and get the Python filename from it.

            """
            return os.path.split(self._pyFileName)[0]

        def getServletClassName(self):
            """Return the class name of the servlet being generated."""
            return self._className

        def getFullClassName(self):
            """Return the class name including package prefixes.

            Won't use this for now.

            """
            raise NotImplementedError

        def getPythonFileName(self):
            """Return the filename that we are generating to."""
            return self._pyFileName

        def getPythonFileEncoding(self):
            """Return the encoding of the file that we are generating."""
            return self._pyFileEncoding

        def getPspFileName(self):
            """Return the name of the PSP file from which we are generating."""
            return self._pspfile

        def getFullPspFileName(self):
            """Return the name of the PSP file including its file path."""
            return self._fullpath

        def setPSPReader(self, reader):
            """Set the PSPReader for this context."""
            self._pspReader = reader

        def setServletWriter(self, writer):
            """Set the ServletWriter instance for this context."""
            self._servletWriter = writer

        def setPythonFileName(self, name):
            """Set the name of the .py file to generate."""
            self._pyFileName = name

        def setPythonFileEncoding(self, encoding):
            """Set the encoding of the .py file to generate."""
            self._pyFileEncoding = encoding

        def setClassName(self, name):
            """Set the class name to create."""
            self._className = name

        def resolveRelativeURI(self, uri):
            """This is used mainly for including files.

            It simply returns the location relative to the base context
            directory, ie Examples/. If the filename has a leading /,
            it is assumed to be an absolute path.

            """
            if os.path.isabs(uri):
                return uri
            else:
                return os.path.join(self._baseUri, uri)

        def getBaseUri(self):
            """Return the base URI for the servlet."""
            return self._baseUri