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 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 least recently 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 instantaneously 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 packaged as a zipped DrJava project file laundry.zip. This file will unzip into a self-contained file tree with root directory laundry. This directory contains the source tree for the laundry framework with root directory edu, a DrJava project profile laundry.drjava and two text files sampleIn} and {{sampleOut used by the sample laundry test class edu.rice.comp211 laundry.tests LaundryTest. Given the text input in sampleIn}, your program should generate the text in {{sampleOut. The provided framework compiles but LaundryTest will fail because most of the members in two key classes DoCommandVisitor and Student have been stubbed out.

After unzipping the laundry.zip file, you can open the DrJava laundry project by starting DrJava, setting the Language Level to Full Java, pulling down the Project menu and selecting the Open command. In the file chooser that pops up, select the project profile file laundry.drjava embedded in the file in the unzipped file tree for laundry.zip. You can save the project state at any point during a DrJava session using the Save command in the Project menu. You can also save individual files within the project using the Save button on command file or the File menu.

The Project Test commands runs all of the JUnit test files in the project.

Your assignment is to fill in the stubbed out members of the DoCommandVisitor and Student (members with degenerate bodies (either return; or return null;). In the process you may choose 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 OO coding style used in the framework.

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 white shirt. 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) in class Main. The main method interface is the only vehicle for executing Java programs directly from 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 command, 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 (<adjective> <article>) of clothing. In response, the simulation outputs

received adjective article

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 <adjective> <article>

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

Acker is wearing adjective article

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

adjective article 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 <adjective> <article>, donned <adjective> <article>

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 <adjective> <article>, ..., <adjective> <article>

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 <adjective> <article>, ..., <adjective> <article>

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 <adjective> <shirt>, <adjective> pants, <adjective> socks

Supporting Code and Programming Details

Our supporting framework is provided in the zip file laundry.zip. The test input in the file sampleIn (with corresponding output) sampleOut is far from comprehensive.

All of our supporting code is included in the unzipped project. Each file resides in a package that is identified by a package statement at the beginning of the file. Most support classes are public so that they can be accessed anywhere. Classes without
a visibility modifier have "default" visibility, which means that they can only be accessed from classes within the same package.

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 methods that return values of type EnumI and ReadIteratorI, the remaining two interfaces.

The IOProcess interface 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 IOProces 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 (

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). 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 Main class should accept a command line argument, a file-name string, (passed in the String[] arguments array to main) indicating that the command stream
should be read from the specified file.
The default should be the GUI IOProcess which also supports console input. 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.