Project 2: Moor Othello?


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Project 2:
Moor Othello?

In this project, you will convert and expand your Project 1 to an object-oriented C++ solution following the
well-known model-view-controller (MVC) software design pattern. In addition to refactoring your original
solution to an object-oriented model, you will expand the Othello game with new functionality and options,
including the ability to ?undo? moves. You will also require the players to input moves that are truly valid
and will result in at least one enemy piece ?ipped. Finally, you will manage dynamic memory requirements
through the use of unique pointers and transferring ownership of memory between several functions and
You will be given a ZIP ?le containing starting points for most of the .h ?les in this project. Those .h ?les
have hints and requirements inside of them; you must add any required functions to the .h ?les as noted in
those ?les, and then implement every function in a corresponding .cpp ?le that you will write in its entirety.
Project Organization
Your project will consist of the following ?les: OthelloMove.h/cpp, a class for encapsulating a single move
on the game board; OthelloBoard.h/cpp, a class representing the state of an Othello game board; OthelloView.h/cpp, a class that prints the current state of a board to the console; and main.cpp, the controller/driver of the game, responsible for handling user input and executing functions on the game model.
You will also need to import your BoardPosition and BoardDirection ?les from your lab assignment.
Class Overview
Your project will consist of these classes. Note that some classes have some functions that have been
implemented for you. You may not change these functions, or add any member variables/functions to the
• OthelloMove: represents a single move on an othello board.
? This class encapsulates information associated with a single move on the board. Moves are
identi?ed by their BoardPosition; they do not keep track of whose turn it is/was when the move
is/was applied. Moves can report whether they are a Pass or not, and can be converted to string
objects for output.
? OthelloMove objects can be created with two constructors. Most typically, they will be placed on
the heap and managed with unique_ptr wrappers.
? To support undo functionality, OthelloMove objects will also maintain a list of pieces that were
?ipped when the move was applied. This will be detailed below.
• OthelloBoard: collects all information needed to represent the state of the game board.
? Contains the 8×8 board game array, plus member variables for the current player, move history,
and board value. The value is now a running total: it is a member variable that is updated
every time a new piece is placed on the board or an existing piece is ?ipped; it does not and
cannot use a loop to walk through the entire board in order to recalculate the board value.
? Public functions for manipulating the game state: ApplyMove, UndoLastMove, GetPossibleMoves.
? The board can now report the list of all legal moves through GetPossibleMoves, which returns
a vector of OthelloMove objects that are legal on the current board state for the current player.
? When applying a move, the board updates its internal state, including saving the applied move
in its move history.
? The board can also undo the most recently applied move, restoring the board state to prior to
that move’s application.
• OthelloView: handles all input and output of othello-related objects.
? Has shared ownership of an OthelloBoard object in order to access the board’s matrix for printing.
? Overloads operator<?< to print a board to the console.
? Has a method ParseMove that takes a string representing an othello move, then constructs a
corresponding OthelloMove object on the heap and returns ownership of it.
• FlipSet: in order to undo an OthelloMove, the move object must ?remember? the set of board positions
that switched players as a result of the move’s application. To do this, each Move object will record
a vector of ??ips?. A FlipSet consists of two member variables: a BoardDirection and a count;
together, these represent a direction on the board in which the given number of enemy pieces were
switch to friendly. Since a FlipSet only describes a single direction of ?ips and a move can ?ip enemy
pieces in multiple directions, an OthelloMove maintains an entire vector of FlipSet objects so it can
remember the directions and numbers of all enemy pieces ?ipped by the move. To undo a move, we
start at its board position and then, for each FlipSet object, walk the given number of squares in the
given direction, restoring the enemy to those positions.
New Functionality
You will re-write your main to not only use your new object-oriented game design, but also support a host
of new game options. Instead of the previous ?show board, ask for move, verify move, apply move? loop, you
will ask the user to input a command, and then parse that command to drive the game objects. Your main
function then looks like this:
1. Initialization: initialize an OthelloBoard object in dynamic storage using a shared pointer, which
you will share with an OthelloView object you construct in automatic storage. You will also need a
local variable for the user’s command choice (a string).
2. Main loop: repeatedly do the following:
(a) Print the game board as in Project 1, using your OthelloView object. The View should print
whose turn it is.
(b) Print a list of all possible moves for the current player. Start by calling OthelloBoard::GetPossibleMoves.
Print out all of the moves in the vector using operator<?<.
(c) Ask the user to input a command. Use the getline function to read in an entire line of text as
the user’s input. Perform one of the following commands depending on the choice:
i. move (r, c) : use your View to parse just the (r, c) portion of this string into a Move
object. If the parse does not fail, then use your vector of possible moves to look for a move
that equals the user’s input. If you ?nd one, this means the entered move is valid and should
be applied, by transferring ownership of the move to the board’s ApplyMove method; if you
cannot ?nd an equivalent move, the move is invalid and you should inform the user.
ii. undo n : undo the last n moves by repeatedly calling OthelloBoard::UndoLastMove. Stop
calling UndoLastMove if you reach the start of the game. (If asked to undo 100000, you
should not end up going into ?negative? move counts.)
iii. showValue: show the current value of the board by calling OthelloBoard::GetValue.
iv. showHistory: show the history of moves applied by the players, with the most recent move
shown ?rst. One move per line, each line starting with the color of the player that applied
that move. See OthelloBoard::GetMoveHistory().
v. quit: quit the game immediately.
(d) Loop part (c) until the user enters a valid move or undoes a move, then loop back to (a).
3. Quit the game when the OthelloBoard notes that it is ?nished (OthelloBoard::IsFinished). The
board keeps track of passes and reports that it is ?nished when 2 passes in a row are recorded. Passes
are still applied to the board via ApplyMove and therefore can be undone with the undo command, but
now the player can only pass if all other options are exhausted.
Pointer Management
This project used to be a lot harder, because students had to keep track of who ?owned? each OthelloMove
object that was created on the heap (and a lot of Move objects will be created on the heap). Thanks to
C++11, this becomes much easier:
1. Anyone who calls GetPossibleMoves will receive a vector that owns a sequence of OthelloMove pointers. If that vector goes out of scope or is cleared, it will delete all of the Move objects automatically.
2. ParseMove also returns ownership of the Move that it creates. This object will be used to see if
the user’s selected move is among the valid possible moves. If the move is valid, ownership will be
transferred to the OthelloBoard; if it is not valid, it will go out of scope and be deleted.
3. Any move that is applied will be owned by the OthelloBoard’s mHistory vector. When a move is
undone and popped from that vector, it will be automatically deleted. If a board is destroyed, its
vector will be destroyed and that will destroy all the moves that it owns.
You just need to call std::move appropriately when transferring ownership of unique_ptr objects. Piece
of cake!
Where to Begin?
I recommend the following order when approaching this project:
1. (This one should be obvious.) Read this entire speci?cation and ask questions about things you don’t
2. Download the BeachBoard ZIP ?le containing starting points for the project.
3. Implement the OthelloMove class: add any functions required by the .h ?le, then write the .cpp ?le.
4. Implement pieces of the OthelloBoard class. There are several functions that must be written in a
.cpp ?le:
(a) First write the constructor, which initializes the mBoard matrix with the initial state of the board,
and sets mValue and mCurrentPlayer to appropriate initial values.
(b) Write ApplyMove, translating your code from Project 1 to work with OthelloBoard’s member
variables and a unique_ptr<OthelloMove parameter (which has an mPosition value instead of
being given a row and column separately). Note that the board now keeps track of the current
player and should update that during the function.
(c) You may have trouble meeting the ApplyMove line limit unless you switch your ?choose a direction?
code to use the CARDINAL_DIRECTIONS array from your lab assignment, and take advantage of
the ?operator+? that adds a BoardPosition and a BoardDirection.
5. Implement the OthelloView class. Write the PrintBoard function, which is a rough translation of
your PrintBoard from Project 1. Implement the operator<?< to call the PrintBoard method of the
OthelloView parameter. Write ParseMove, using an istringstream to read in the move’s board
6. You can now run the debugging code in the main I gave you. This code applies three simple moves to
a default board and prints the board after each move. Examine the code and the output to make sure
you translated ApplyMove correctly. At this point, you have e?ectively translated your entire Project
1 solution to an object-oriented model, and can work on the new behavior
7. Implement the new behavior for the othello game:
(a) Augment your code to perform the new behaviors expected of ApplyMove: updating the mValue
member variable to re?ect the changed board value, recording the FlipSets of the move, and
saving the applied move to the board’s history vector.
(b) Write GetPossibleMoves, noting the requirements in the .h ?le for how to order the moves.
(c) Write an empty function for UndoLastMove and save it for later.
8. You are now ready to start your real main. Comment out the debugging code. Implement the ?move?
command so you can play the game with your own moves. Implement showValue and showHistory
9. Now go back and work on UndoLastMove and the ?undo n ? command.
10. Easy :).
Line Limits
Yes, there are line limits.
• Constructor: 5 lines
• ApplyMove: 18 lines
• GetPossibleMoves: 18 lines
• UndoLastMove: 12 lines
• operator==(const OthelloMove &rhs): 1 line
• operator std::string(): 5 lines
• operator<?<(ostream &lhs, const OthelloView &rhs): 3 lines
• operator<?<(ostream &lhs, const OthelloMove &rhs): 1 line
int main: 80 lines
Easy to Overlook
Summary of things that are easy to overlook:
• You do not cout the OthelloBoard itself; you cout the OthelloView object. You can use cout with
OthelloMove objects.
• The board’s history vector lists moves in the order they were applied. When showHistory is run, you
have to print the moves in reverse order from how they appear in the history vector.
• When printing the history, you must indicate which player applied which move.
• Passes should be treated like any other move by main. You can only pass if pass is in the vector of
possible moves. pass will only be in the vector if there are no other possible moves.
• You cannot use any additional loops to calculate the value of a board. Every time you place a piece
or ?ip a piece, you must adjust the value by some small amount. (Think about it… what happens to
the value of the board when you place a new black piece vs. ?ip a white to a black?)
• The game is over when IsFinished() returns true.

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