CS U370 Assignment #6
Section:  Clinger
Assigned:  Friday, 14 November 2008
Corrected:  Tuesday, 18 November 2008 (see ! in column 79)
Due:  Friday, 21 November 2008

The purposes of this assignment are:

 * To illustrate the Visitor pattern.
 * To illustrate function objects.
 * To show how winner-take-all contests tend to magnify small
   advantages.

This assignment is to be done by individual students, not by
pairs or teams of students.  Collaboration between students is
forbidden on this assignment.  You are responsible for keeping
your code hidden from all other students.

You will complete an implementation in Java of the ForEach
class specified below.  Turn in your work on this assignment
before 10 pm on the due date by sending electronic mail to:
will@ccs.neu.edu

with subject
    CSU370 assignment 6

and a body that consists of nothing but your ForEach.java                     !
file.  That file should begin with a block comment that lists
    1.  Your name, as you want the instructor to write it.
    2.  Your email address.
    3.  Any remarks that you wish to make to the instructor.

Part of your grade will depend on the quality, correctness, and
efficiency of your code, part will depend on the readability of
your code (comments and indentation), and part will depend on
how well you follow the procedure above for submitting your work.
Late assignments may be discounted, and very late assignments may
be discarded.

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

Your assignment is to write the code for a single file,
ForEach.java, that implements the ForEach class specified
below.

You are given two files in /course/csu370wc/Assignments/A6:

    VotingDistrictVisitor.java
    Test6.java

The VotingDistrictVisitor.java file defines the
VotingDistrictVisitor interface, so that file is
essential for this assignment.  The Test6.java file
contains a simple test program; you will need to
supplement that test program with further tests.

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

Specification of the ForEach class.

The ForEach class shall be implemented in Java, and will be
tested using Sun's Java 2 Runtime Environment, Standard
Edition, version 1.6.0.  The code for this class will be in
the default package, and shall define a public class named
ForEach.

The ForEach class is a client of both the VotingDistrict ADT
(as specified in assignment #1) and the SetOfVotingDistrict
ADT (as specified in assignment #5).  It should therefore
work with all possible implementations of those ADTs.  It
should also work with all function objects that implement
the VotingDistrictVisitor interface.

The ForEach class shall provide the following public static
method:

Signature:

    forEach : VotingDistrictVisitor x SetOfVotingDistrict ->

Informal specification:

If s.isEmptySet(), then ForEach.forEach(v, s) does nothing.

Otherwise let d = s.choose() and s2 = s.without(d).
ForEach.forEach(v, s) first calls v's visit method on d,
and then behaves as though it had called itself recursively
on v and s2.  That is, ForEach.forEach(v, s) behaves like
this:

    v.visit(d);
    ForEach.forEach(v, s2);

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