CS U670 Assignment #5 [Revision 2]
Assigned: Tuesday, 8 April 2008 (revised 12 April)
Due: Tuesday, 22 April 2008

Working in a team of three students, write a program
that collaborates with similar programs written by
any number of other teams to find the enchanted frog
and carry him/her 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 of the possible output elements 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.

--------------------------------------------------

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

<choice xmlns="http://relaxng.org/ns/structure/1.0"
        datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
  <element name="outside">
    <empty/>
  </element>
  <element name="room">
    <interleave>
      <element name="purpose">
        <text/>
      </element>
      <zeroOrMore>
        <element name="characteristic">
          <text/>
        </element>
      </zeroOrMore>
      <zeroOrMore>
        <element name="character">
          <element name="species">
            <choice>
              <value>prince</value>
              <value>princess</value>
              <value>soldier</value>
              <value>minion</value>
              <value>peon</value>
              <value>dragon</value>
            </choice>
          </element>
          <element name="description">
            <text/>
          </element>
        </element>
      </zeroOrMore>
      <zeroOrMore>
        <element name="item">
          <choice>
            <element name="frog">
              <empty/>
            </element>
            <element name="paper">
              <text/>
            </element>
            <element name="treasure">
              <attribute name="style">
                <text/>
              </attribute>
              <data type="int"/>
            </element>
            <element name="shield">
              <attribute name="style">
                <text/>
              </attribute>
              <data type="int"/>
            </element>
            <element name="weapon">
              <attribute name="style">
                <text/>
              </attribute>
              <data type="int"/>
            </element>
          </choice>
        </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>

--------------------------------------------------

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

<choice xmlns="http://relaxng.org/ns/structure/1.0"
        datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
  <element name="stop">
    <empty/>
  </element>
  <element name="enter">
    <empty/>
  </element>
  <element name="exit">
    <choice>
      <value>up</value>
      <value>down</value>
      <value>north</value>
      <value>east</value>
      <value>south</value>
      <value>west</value>
    </choice>
  </element>
  <element name="grasp">
    <choice>
      <element name="frog">
        <empty/>
      </element>
      <element name="paper">
        <text/>
      </element>
      <element name="treasure">
        <attribute name="style">
          <text/>
        </attribute>
        <data type="int"/>
      </element>
      <element name="shield">
        <attribute name="style">
          <text/>
        </attribute>
        <data type="int"/>
      </element>
      <element name="weapon">
        <attribute name="style">
          <text/>
        </attribute>
        <data type="int"/>
      </element>
    </choice>
  </element>
  <element name="drop">
    <empty/>
  </element>
  <element name="write">
    <text/>
  </element>
  <element name="assault">
    <empty/>
  </element>
</choice>

--------------------------------------------------

Rules.

An <outside></outside> element indicates you have
escaped from Prince Charming's castle, but the frog
is still inside the castle.  You should respond with
either a <stop></stop> or <enter></enter> message.
A <stop></stop> message will be acknowledged by a
<gameover>...</gameover> message; <enter></enter>
will cause you to reenter the castle, but you will
not necessarily reenter the castle through the same
exit by which you left it.

A <room>...</room> element describes a room and its
contents.  Each room's purpose, characteristics, and
exits are fixed (although the characteristics and
exits may be presented in any order).  Each room may
also hold any number of characters and items, which
may vary over time.

Each character is a participant in the game.  Some
of those characters are generated and controlled by
the referee program, but some of the peons may be
controlled by another team's game-playing program.

Items are small enough to be grasped, but you can
only grasp one item at a time.

The main goal of the game is to find the frog, grasp
it, and carry it out of the castle.

Paper gives you a way to communicate with the peons
controlled by other teams.  You can read the contents
of a paper item without grasping it.  To change its
contents, however, you must first grasp the paper.
Then you can write a new message on the paper, which
overwrites its previous contents.  (It's magic paper.)
You may drop paper immediately after writing on it,
or you may carry it with you.

Treasure has numerical value, but is not as valuable
as the enchanted frog.  If you are holding treasure,
then you are more likely to be assaulted by dragons.
Dropping treasure in the presence of a dragon may
earn its friendship.

Shields have numerical value.  Higher values are more
protective against assaults.

Weapons have numerical value.  Higher values are more
deadly.  Heat-seeking missiles and thermonuclear weapons
should be employed only in well-ventilated areas.

When you launch an assault, you assault all of the
other characters in the room.  Assaults can be launched
at any time, but will be less effective if you are
holding a frog, paper, treasure, or shield than if
you are holding a weapon.  Princes, princesses, and
soldiers have been trained in the martial arts; it's
easier to murder minions and unarmed peons than
soldiers or royalty.  Dragons don't like to be poked,
and are especially annoyed by automatic weapons.

In general, the referee program will ignore inappropriate
messages.  The referee program will interpret consecutive
inappropriate messages as a sign of derangement, and will
respond with a <gameover>...</gameover> message.