Homework 10: SimLaundry 2010

Due 1 April 2009 at 11:00 A.M. (Wednesday before class)

Preface

This assignment has a long description but the coding involved is straightforward. Most of the code for the full application has been written by the course staff. In the solution written by the course staff, the code remaining for you to write consists of approximately 175 lines (including some terse comments and whitespace lines).

Overview

Rice student J. H. Acker has decided to drop out of school and become a
high-tech billionaire by marketing a virtual reality
game based on Acker's own personal hygiene. The game is called
SimLaundry 2010, and it models the laundry habits of a typical college
student. In this assignment, you will help Acker create this game, in
return for a cut of the profits and a good Comp 211 grade.

We will assume there are only three types of clothing: shirts, pants, and
socks. (We will all enjoy this assignment a lot more if we don't have to
think about Acker's underwear.) Acker neatly stacks clean shirts, pants, and
socks in {\em separate} piles on a shelf in his closet.

When changing clothing, Acker throws dirty clothing onto a pile in the
corner of the closet, then selects the top clean item of a particular type
from the closet shelf; the resulting outfits rarely coordinate, but Acker
is no slave to fashion. If there are no clean clothes of a particular
variety, Acker resorts to using dirty laundry and removes the leastrecently worn article of that type from dirty laundry pile, smells it, and always decides it can be
worn again after all. (Acker never has to go naked, because there is at
least one item of the desired type in the laundry, namely the one Acker just
removed.)

When doing laundry, Acker removes fifteen (or fewer, if the pile isn't that
large) items
from the top of the dirty clothes pile. In the simulation,
a load of clothes is laundered and dried instanteously and placed on a
table for clean clothes reserved for Acker in the laundry room.
Acker changes clothes so infrequently that the washing and drying time is
negligible, so our simulation is a good approximation.
The garments in each load of clean clothes
are piled in exactly the same order they
appeared in the dirty pile. Acker fills the washer and
dryer so full that the clothing doesn't get jumbled up.

Eventually Acker retrieves the oldest clean laundry load, folds
it, and places it on the closet shelf. In the process, he reverses the
order of the clothing within the load; whatever was on the bottom
of the pile on the laundry table is now on top of the appropriate
pile (shirts, pants, or socks) of clean clothes on the shelf.
Hence, if a blue shirt was on
top of a white one in the dirty clothes pile and they are washed in
the same load, then the white shirt will be on
top of the blue one on the closet shelf.

Acker periodically receives gifts of clothing from relatives,
which are placed on top of the appropriate pile on the closet shelf. He never buys
any clothes.

Acker never discards clothing, no matter how threadbare, but does, on rare
occasions, lose some. Not even Acker loses clothes being worn,
but they can be lost from anywhere else, including the closet shelf, the
dirty laundry pile, and
the laundry room.

For the purposes of this assignment, a pair of socks is an indivisible
article of clothing; we make the unrealistic assumptions that single socks
are never lost and that Acker does not wear mismatched socks. Also, you
needn't be any more concerned than Acker is about separating white and dark
laundry or other such niceties.

What You Must Do

The course staff is providing a framework for writing this program that includes
many classes and interfaces. The framework is available either as a a single file HW10.java (https:wikiriceedudisplayCSWIKI211hw10HW10java) (with a skeleton definition for the class Student=) or as an archive (.zip file) laundry.zip of many files, one for each class and interface in =HW10.java .

Your job is to fill in the members of the Student class which is provided in skeleton form. In the process you may have to define some new classes to support your Student class implementation. The Student class models the laundry habits of Acker. In our test simulations, we will typically only create a single
instance of Student representing Acker, but your code should support multiple students
(e.g., Acker and his brothers) at a time. Since these students do not interact with each other, supporting this form
of multiplicity is a trivial consequence of writing your code is OO style.

The Student class includes:

the name of the student,

the closet shelf with its piles of clean clothes,

the dirty laundry pile, and

the laundry room with its piles of laundered garmets sitting on tables.

and methods to
manipulate those data representations to perform the specified simulation.

When the simulation begins, Acker is
wearing white pants, white socks, and a
whiteshirt. The closet shelf, dirty laundry pile, and laundry facilities are all
initially empty. Your program should start execution using the special method
public static void main(String[] args)
which is the only vehicle for executing Java programs directly on the command line.
(DrJava has a main method for this reason.)

Form of Event Commands

Your program executes a loop that repeatedly reads input from an input ``process'' that returns
Command objects. The input process (provided by our supporting
framework) reads a series of event
description commands, one to a line, either from the console or from a file. The input process converts
a stream of characters to Command
objects which are passed to your program.
In addition to performing
the specified common, your program should output a brief description of for each command that it performs
in the exact format described below. In the following list
of commands, the output line specifies what your program should print.

receive adjective article

means Acker received a gift of the specified article of clothing.
In response, the simulation outputs

received <em>adjective</em> <em>article</em>

and updates the state of the StudentEnvironment .
For example,

receive argyle socks

generates

received argyle socks

and adds the argyle socks to the top of the socks pile on the shelf.

lose adjective article

means Acker misplaced the specified article of clothing.
If the item exists and Acker is not wearing it, the simulation outputs

lost <em>adjective</em> <em>article</em>

and updates the state of the StudentEnvironment accordingly.
If Acker is wearing it, the simulation outputs

Acker is wearing <em>adjective</em> <em>article</em>

and leaves the StudentEnvironment unchanged.
If the item does not exist, the simulation outputs

<em>adjective</em> <em>article</em> does not exist

and leaves the StudentEnvironment unchanged.

change article

means Acker doffed the specified article of clothing, discarding it in the dirty laundry pile, and donned a replacement article using the protocol described above.
In response, the
simulation
outputs

doffed <em>adjective</em> <em>article</em>, donned <em>adjective</em> <em>article</em>

describing the article doffed and the article donned.

launder

means Acker washed and dried a load of laundry.
If the dirty clothes pile is not empty, the simulation outputs

washed <em>adjective</em> <em>article</em>, ..., <em>adjective</em> <em>article</em>

listing the clothes in the order they were removed from the dirty clothes pile.
If the dirty clothes pile is empty, the simulation outputs

nothing to wash

fold

means Acker retrieved a load of laundry, folded it, and put it on the
closet shelf. If a load of laundry is available, the simulation
outputs

folded <em>adjective</em> <em>article</em>, ..., <em>adjective</em> <em>article</em>

for the oldest unfolded load.
List the clothes in the order they are placed on the shelf. Hence the
top garment on the shelf should be the last one listed.
If no load of laundry has been washed and dried, then the simulation
outputs

nothing to fold

If the oldest load is empty (because all items in it
were lost), the simulation outputs

folded empty load

outfit

asks "what is Acker wearing?" The simulation outputs

wearing <em>adjective</em> shirt, <em>adjective</em> pants, <em>adjective</em> socks

Supporting Code and Programming Details

Our supporting framework is provided in two different forms:

• As a zip file laundry.zip including a source file for each class; and
• As a set of four files HW10.java (https:wikiriceedudisplayCSWIKI211hw10HW10java)tinyin (https:wikiriceedudisplayCSWIKI211hw10tinyin) tinyout (https:wikiriceedudisplayCSWIKI211hw10tinyout)LaundryTest.java (https:wikiriceedudisplayCSWIKI211hw10LaundryTestjava) where HW10.java is a single file containing all of our support code, tinyin and tinyout are sample input and output files ( tinyout is the correct output for tinyin=), and =LaundryTest.java" is a small JUnit test file for the laundry application that invokes the application on =tinyin and tests whether the output matches tinyout . This test suite is far from comprehensive.

All of our supporting code resides in the default package and none of the classes are public so all of the code can be placed in a single file. We are providing multi-file version of the source so that you can (optionally) gain experience with code bases where every public class resides in a separate file. All subsequent assignment will use the package system where most classes are public and reside in separate files.

Our supporting framework includes
an input processor that reads event commands from
the input stream and returns high level data representations for
these commands. The input processor can also print
debugging output describing the state of your simulation before
each command is performed. To communicate with your code,
the input processor uses four interfaces:

IOProcess which describes the visible methods supported
by the input processor;

StudentEnvironment which describes methods for inspecting the
state of Acker's environment;

EnumI which describes methods for inspecting (but not
mutating!) lists within Acker's environment; and

ReadIteratorI which includes methods for moving a cursor
through lists implementing the EnumI interface.

The interfaces are already defined in the framework provided by the course staff.

The input processor class !TerminalIO
implements the IOProcess interface. You are welcome to
inspect the code of TerminalIO but it relies heavily
on the Java I/O library, particularly the class StreamTokenizer .
To understand this code, you will need to read Chapter 11 of JLS (or similar reference).
The framework also includes implementations of
EnumI and ReadIteratorI as part of a BiList (mutable circular doubly linked list) class implementation.

Your Student class must implement the StudentEnvironment interface, which includes
the simulate method supporting
the laundry simulation. Within
this class you must implement that return values of type
EnumI and ReadIteratorI, the remaining two
interfaces.

The IOProcessinterface that provides your program with a command input stream introduces two
class definitions defining unions (composites without recursion): Garment,
specifying the representation of garments that appear in the input stream,
and Command,
specifying the representation of event description commands. Both
classes include the hooks required to support the visitor pattern.
The data definition for Garment is important because we will subsequently
provide you with an graphical
IOProcess that animates the state of your implementation before each
command. This IOProcess will expect the garments that appear as
elements in lists (as revealed by the EnumI and
ReadIteratorI interfaces) to be
instances of the Garment class. Hence,
you must use the
representation of garments that our class Garment provides.

The file Student.java contains comments
describing all of the members that you need to write. In fact,
you only need to define the member methods of the inner class DoCommandVisitor .
Early next week, we will upload
a GraphicalIO class implementing IOProcess
that supports a graphics window with buttons that generate
input commands, a screen that animates the simulation, and
a text output buffer that shows conventional terminal output. this
input processor supports exactly the same IOProcess interface as
the TerminalIO process provided herein.

The IOProcess interface includes a method
PrintStream open(StudentEnvironment a, boolean debug)
which initializes an IOProcess object
for a laundry simulation of
the specified environment and returns the PrintStream
object to be used for terminal output. (Up to now you have implicitly
used the PrintStream object System.out .)
The PrintStream method println(String s) prints the string s followed
by a newline character to
the PrintStream .
The boolean debug argument
indicates whether or not debugging output should be produced.
The IOProcess interface also includes a method nextCommand which reads
the next command from the input channel supported by
the IOProcess object.

Each call on nextCommand returns the next
command in the stream provided by the IOProcess object, until it reaches an end-of-file (Control-d from the
keyboard). End-of-file is reported as a null reference
of type Command .

The nextCommand method in TerminalIO
processes character strings
consisting of words separated by ``space'' characters such as ' '
and '\n' . A word is any sequence of
printable characters other than space, '\n' (newline), and
'\r' . (return).
An adjective must be a single word. An
article
must be one the words shirt , pants , or
socks .
The same adjective, say argyle may be applied to
garments of different types, but there are no duplicate items
of clothing.

Your program must pass a boolean debug {{ flag to the =IOProcess}}
it is using ( TerminalIO for now ). The value of the flag
sould be is true iff the command line argument -d or -debug is passed
to main .

When we upload the graphics version of the IOProcess ,
your main method in the Student class should accept a command
line argument -graphics (passed in the String[] arguments array to =main=)
indicating that the graphics version of
the IOProcess should be used instead of the terminal version.
The default should be the terminal IOProcess . If you are interested
in implementation details of these interfaces and classes, please read
relevant source files.

Efficiency

For this assignment, you should be concerned
about relevant asymptotic efficiency. Choose the simplest representation
that yields good performance on inputs of plausible size.

Changing an article of clothing should take constant time (i.e., no
searching should be done) provided there's an appropriate garment on the shelf.
If the shelf contains no clothing of that type, then in the common case
we expect to find one of those near the bottom of the pile, no matter how
big the pile is: make that case fast. Infrequent operations need not be
particularly fast, because they have little impact on the running time of the
entire system. (Suppose one operation accounts for 5% of the runtime, and
we can make it run 10 times as fast. How does that compare to making an
operation that accounts for 25% of the runtime twice as fast?)

Example

With Acker initially wearing white shirt, socks, and pants, given the input:

receive blue socks
receive green pants
receive red shirt
change socks
receive yellow shirt
change shirt
outfit
change socks
launder
change pants
fold
change socks

your program should produce:

received blue socks
received green pants
received red shirt
doffed white socks, donned blue socks
received yellow shirt
doffed white shirt, donned yellow shirt
wearing yellow shirt, white pants, blue socks
doffed blue socks, donned white socks
washed blue socks, white shirt
doffed white pants, donned green pants
folded blue socks, white shirt
doffed white socks, donned blue socks

The sample input and output files tinyin and tinyout
are a good starting point for testing your program but they are far
from exhaustive.
You are responsible for testing your own program. Since your class
containing main is called Student , the terminal command

java Student < infile > outfile

will take input from file infile and direct output to
file outfile . If you omit > outfile , output
will appear in the standard output stream.

You can run the main method from within DrJava by typing

java Student infile

DrJava does not recognize command line input or output redirection, so
there is no way to redirect output to a file, but it is printed to the console tab. The infile command
argument is supported by the skeleton code we have provided in the Student class.

Addendum

The graphical interface code was written on the assumption that your program resides in a package named laundry and that numerous fields of classes in your program are public. It also relies on deprecated library classes and has no supporting test code. It is a major project to rewrite it to work with the current problem specification. The course staff may succeed in getting a version working later in the term, but not before Wednesday. You can ignore all references to "graphics" in the assignment.