CS U670 Assignment #5.
Assigned: Tuesday, 19 February 2008
Due: Friday, 29 February 2008

Working in a team of three students, write a program
that finds its way out of Prince Charming's castle.

Your program should read messages from standard input
and write messages to standard output; depending on
your i/o library or programming language, you may need
to flush an output buffer after each message.  Your
program should begin by reading exactly one message
from standard input; if that message has the form of
a <room>...</room> element, then your program should
write exactly one <exit>...</exit> element to standard
output and repeat; if the input message is anything
other than a <room>...</room> element, then your program
should exit normally.

The syntax of input and output messages is described by
the Relax NG specifications shown below.  Since we are
working with messages, not documents, we will restrict
all messages to Ascii characters and to the elements
shown in the Relax NG specifications.  XML comments
and other XML folderol will not be permitted in messages.

Your program must run on any CCIS Solaris machine without
requiring the installation of software or libraries that
are not already installed on those machines.  If your
program uses libraries that are not already available on
CCIS Solaris machines, then those libraries must be part
of the code you submit for this assignment.  You must,
of course, have permission to include those libraries as
part of your submission, which may make it impossible
for you to use some libraries in your program.

Your program must be accompanied by a README file that
identifies all of the files you are submitting for this
assignment and tells the instructor how to build and to
run your program.  You should assume the instructor has
some familiarity with programming but knows absolutely
nothing about the specific programming language(s) and
other software used by your program.

You will submit this assignment using a Unix shell script
provided by the instructor.  This shell script and the
instructions for using it will be similar to the shell
script and instructions given for the previous assignment,
but may incorporate some improvements.

Late assignments may be discounted, and very late assignments
are likely to be discarded.

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<!-- Relax NG specification of input messages -->

<choice xmlns="http://relaxng.org/ns/structure/1.0">
  <element name="room">
    <interleave>
      <element name="purpose">
        <text/>
      </element>
      <zeroOrMore>
        <element name="characteristic">
          <text/>
        </element>
      </zeroOrMore>
      <element name="exits">
        <oneOrMore>
          <element name= "exit">
            <choice>
              <value>up</value>
              <value>down</value>
              <value>north</value>
              <value>east</value>
              <value>south</value>
              <value>west</value>
            </choice>
          </element>
        </oneOrMore>
      </element>
    </interleave>
  </element>
  <element name="gameover">
    <element name="outcome">
      <text/>
    </element>
  </element>
</choice>

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<!-- Relax NG specification of output messages -->

<element name="exit" xmlns="http://relaxng.org/ns/structure/1.0">
  <choice>
    <value>up</value>
    <value>down</value>
    <value>north</value>
    <value>east</value>
    <value>south</value>
    <value>west</value>
  </choice>
</element>

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