org.pesullivan.game.mill.engine
Class MillBoard

java.lang.Object
  org.pesullivan.game.mill.engine.MillBoard

All Implemented Interfaces:

Board

public final class MillBoard
extends java.lang.Object
implements Board

A Nine Men's Morris implementation of Board.

Field Summary

static int	AXIS_A Identifies axis A of a coordinate system that locates spots on the board.
static int	AXIS_B Identifies axis B of a coordinate system that locates spots on the board.
static int	MAX_SPOT_COORDINATE Bounds of a square cartesian coordinate system that locates spots on the board.
static int	N_MAX_MEN_OUT Maximum number of men that can be taken from one side.
static int	N_MEN_PER_SIDE Number of men per side.
static int	N_ROWS Number of Mill board row lines.
static int	N_SPOTS Number of Mill board row intersecions.
static int	N_SPOTS_PER_ROW Number of spots in a mill row.
static int	NO_SIDE Value signifying the absence of a player side.
static int	NO_SPOT Value signifying the absence of a playing spot.
static int	ROW_SPOT_0 Identifies the first of 3 spots in a row.
static int	ROW_SPOT_1 Identifies the middle of 3 spots in a row.
static int	ROW_SPOT_2 Identifies the last of 3 spots in a row.

Method Summary

Board	copy() Return a copy (ignoring move iterator state).
int	getActiveSide() Get an index identifying the active side (whose turn it is).
int	getAlteredLevelOfPlay(int level) Return the number of turns the Game engine should look ahead.
int	getEmptyNeighborCount(int spot)
Move	getFirstMove() Reset the board's move iterator and return the first move.
int	getGoodEnoughScore(int plannedScore, int levelOfPlay) Return a score which is good enough that a player need look no farther to see how much better it gets.
Move	getLastMoveExecuted() Return the last move that was executed.
int	getMenLeft() Return the number of men left to be placed by the active side.
int	getMenLeft(int side) Return the number of men left to be placed by the given side.
int	getMenOut(int side) Return the number of men taken from the given side.
static MillMove	getMove(java.lang.String positionText) Return the move described by positionText.
Board	getNewBoard() Return a new board ready for a new game.
Move	getNextMove() Return the next move based on the board's move iterator.
static java.lang.String	getPositionText(int spot) Return text notation for the given move spot.
int	getProgress() Return a measure of progress towards the game conclusion.
int	getRepetitionPenalty(int nRepeats) Get a score penalty for repeating a position so many times.
int	getScore() Express the position's merits as a scalar relative score.
static int	getSpot(int coordinateA, int coordinateB) Return the intersection spot index at coordinate a,b.
static int	getSpot(java.lang.String positionText) Get the spot indicated by the given textPosition.
static int	getSpotCoordinate(int spot, int axis) Return an a or b cartesian coordinate for the given board spot.
static int	getSpotCoordinate(int row, int spot, int axis) Return an a or b cartesian coordinate for the given row spot.
int	getSpotSide(int spot) Get the side of the piece currently occupying the given spot.
int	getSpotSide(java.lang.String positionText) Get the side of the piece currently occupying the given spot.
Move	getUndefinedMove() Return a new move which has not yet been defined.
void	go(Move mv) Execute the given move.
boolean	isFlying() Return true if the current move is a flying move.
boolean	isGameOver() Return true if the active side has no move.
boolean	isPlacing() Return true if the current move is a placing move.
boolean	isSame(Board board) Compare board states (ignoring move iterator state).
boolean	isSliding() Return true if the current move is a sliding move.
boolean	isTaking() Return true if the current move is a taking move.
boolean	isTakingAny() Return true if the player can take even from a mill.
boolean	isTranslating() Return true if the current move is a sliding or flying move.
boolean	isValidMove(MillMove move) Return true if the given move is valid given the board state.
boolean	isWon() Return true if either side has won.
boolean	isWon(int score) Return true if the given score means that either side won.
void	setFrom(Board board) Set the board state to that of board, (ignoring move iterator state).
void	setFromJSON(org.json.simple.JSONObject jsonBoard) Set this board based on the parameter.
org.json.simple.JSONObject	toJSONObject()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NO_SPOT

public static final int NO_SPOT

Value signifying the absence of a playing spot. A playing spot is one of 24 positions on the board onto which pieces are placed.

See Also:

Constant Field Values

NO_SIDE

public static final int NO_SIDE

Value signifying the absence of a player side. There are two players so player sides can be either 0 or 1.

See Also:

Constant Field Values

MAX_SPOT_COORDINATE

public static final int MAX_SPOT_COORDINATE

Bounds of a square cartesian coordinate system that locates spots on the board. The 24 playing spots occupy a subset of the 6X6 matrix.

See Also:

Constant Field Values

AXIS_A

public static final int AXIS_A

Identifies axis A of a coordinate system that locates spots on the board.

See Also:

Constant Field Values

AXIS_B

public static final int AXIS_B

Identifies axis B of a coordinate system that locates spots on the board.

See Also:

Constant Field Values

ROW_SPOT_0

public static final int ROW_SPOT_0

Identifies the first of 3 spots in a row.

See Also:

Constant Field Values

ROW_SPOT_1

public static final int ROW_SPOT_1

Identifies the middle of 3 spots in a row.

See Also:

Constant Field Values

ROW_SPOT_2

public static final int ROW_SPOT_2

Identifies the last of 3 spots in a row.

See Also:

Constant Field Values

N_ROWS

public static final int N_ROWS

Number of Mill board row lines.

See Also:

Constant Field Values

N_SPOTS

public static final int N_SPOTS

Number of Mill board row intersecions.

See Also:

Constant Field Values

N_SPOTS_PER_ROW

public static final int N_SPOTS_PER_ROW

Number of spots in a mill row.

See Also:

Constant Field Values

N_MEN_PER_SIDE

public static final int N_MEN_PER_SIDE

Number of men per side. This number is in the name Nine Men's Morris.

See Also:

Constant Field Values

N_MAX_MEN_OUT

public static final int N_MAX_MEN_OUT

Maximum number of men that can be taken from one side. When this many men are taken the game is over.

See Also:

Constant Field Values

Method Detail

setFromJSON

public void setFromJSON(org.json.simple.JSONObject jsonBoard)

Description copied from interface: Board

Set this board based on the parameter.

Specified by:

setFromJSON in interface Board

toJSONObject

public org.json.simple.JSONObject toJSONObject()

Specified by:

toJSONObject in interface Board

Returns:

this board as a JSONObject.

getNewBoard

public Board getNewBoard()

Description copied from interface: Board

Return a new board ready for a new game.

Specified by:

getNewBoard in interface Board

getUndefinedMove

public Move getUndefinedMove()

Description copied from interface: Board

Return a new move which has not yet been defined.

Specified by:

getUndefinedMove in interface Board

copy

public Board copy()

Description copied from interface: Board

Return a copy (ignoring move iterator state).

Specified by:

copy in interface Board

setFrom

public void setFrom(Board board)

Description copied from interface: Board

Set the board state to that of board, (ignoring move iterator state).

Specified by:

setFrom in interface Board

Parameters:

board - the original board to copy.

isSame

public boolean isSame(Board board)

Description copied from interface: Board

Compare board states (ignoring move iterator state).

Specified by:

isSame in interface Board

Returns:

true if the board states are identical.

getActiveSide

public int getActiveSide()

Description copied from interface: Board

Get an index identifying the active side (whose turn it is).

Specified by:

getActiveSide in interface Board

Returns:

index 0 or 1.

getScore

public int getScore()

Description copied from interface: Board

Express the position's merits as a scalar relative score. A score of zero indicates that both sides have equal merit, while a score greater than zero indicates that the active side is winning. The score is calculated with respect to the current board state without looking ahead. You can improve Board's play by finding optimal weights (as with genetic algorithms) for getScore's criteria. Humans surpass computers in performance of this method.

Specified by:

getScore in interface Board

Returns:

the score from the perspective of the active side.

getGoodEnoughScore

public int getGoodEnoughScore(int plannedScore,
                              int levelOfPlay)

Description copied from interface: Board

Return a score which is good enough that a player need look no farther to see how much better it gets. The Game engine optimizes by pruning move search tree branches using this score. The returned score should be just above what is probable based on plannedScore for optimal performance. Towards the end game the returned score should be far higher than what is probable. levelOfPlay is optionally used to set expectations for what is good enough.

Specified by:

getGoodEnoughScore in interface Board

Parameters:

plannedScore - expectations based on a previous search.

levelOfPlay - level of play requested by the Game engine.

Returns:

the score from the perspective of the side with plannedScore.

getRepetitionPenalty

public int getRepetitionPenalty(int nRepeats)

Description copied from interface: Board

Get a score penalty for repeating a position so many times. The Game engine uses this penalty to encourage the choice of a different position than one that has already occurred nRepeats times. This encourages variety of play and draw avoidance at the expense of good judgment.

Specified by:

getRepetitionPenalty in interface Board

Parameters:

nRepeats - the number of times this position has already occurred during this game.

Returns:

a positive score penalty.

getFirstMove

public Move getFirstMove()

Description copied from interface: Board

Reset the board's move iterator and return the first move. The board's move iterator iterates all moves that are possible from the current position. Each move represents the smallest discrete decision a player can make, and each turn is comprised of 1 or more moves. Even a skipped turn is described by a non-null Move. For better performance return the most promising moves first.

Specified by:

getFirstMove in interface Board

Returns:

a readonly move or null if the game is over.

getNextMove

public Move getNextMove()

Description copied from interface: Board

Return the next move based on the board's move iterator.

Specified by:

getNextMove in interface Board

Returns:

a readonly move or null if the board's move iterator is done.

getLastMoveExecuted

public Move getLastMoveExecuted()

Description copied from interface: Board

Return the last move that was executed.

Specified by:

getLastMoveExecuted in interface Board

Returns:

a readonly move or null if it is a new game.

go

public void go(Move mv)

Description copied from interface: Board

Execute the given move. If the active side can't go again after the move is executed, the side is changed.

Specified by:

go in interface Board

See Also:

Board.getFirstMove(), Board.getNextMove()

getAlteredLevelOfPlay

public int getAlteredLevelOfPlay(int level)

Description copied from interface: Board

Return the number of turns the Game engine should look ahead. Each turn has one move and possibly several "go again" moves, so the number of moves looked ahead may exceed the level of play. Even though the game engine may request a certain level of play, getAlteredLevelOfPlay() may arbitrarily override it at various stages of the game for performance reasons.

Specified by:

getAlteredLevelOfPlay in interface Board

Parameters:

level - the level of play requested.

Returns:

an integer greater than 0.

isWon

public boolean isWon(int score)

Description copied from interface: Board

Return true if the given score means that either side won.

Specified by:

isWon in interface Board

getProgress

public int getProgress()

Description copied from interface: Board

Return a measure of progress towards the game conclusion. The Game engine uses this measure to encourage choice of a move which concludes the game sooner. Note that getGoodEnoughScore may subvert this method by pruning (and thus ignoring) moves which conclude the game sooner.

Specified by:

getProgress in interface Board

Returns:

a number that increases as the game progresses.

getEmptyNeighborCount

public int getEmptyNeighborCount(int spot)

Returns:

number of empty neighbours adjacent to the given spot.

getPositionText

public static java.lang.String getPositionText(int spot)

Return text notation for the given move spot.

See Also:

getMove(String positionText)

getMove

public static MillMove getMove(java.lang.String positionText)

Return the move described by positionText.

Parameters:

positionText - text notation describing a move. Position text is of the form {square}{point}[{square}{point}] where: {square} is X, Y or Z starting with the outermost square and {point} is 1,2...8 starting at the upper left and going clockwise.

Returns:

the move if found otherwise null.

isGameOver

public boolean isGameOver()

Return true if the active side has no move. This routine leaves the move iterator in an undefined state.

isWon

public boolean isWon()

Return true if either side has won.

getMenLeft

public int getMenLeft()

Return the number of men left to be placed by the active side.

getMenLeft

public int getMenLeft(int side)

Return the number of men left to be placed by the given side.

getSpotSide

public int getSpotSide(int spot)

Get the side of the piece currently occupying the given spot.

Parameters:

spot - 0 based index of the given board spot.

Returns:

side index (0 or 1) or NO_SIDE if the spot is unoccupied.

See Also:

N_SPOTS

getSpotSide

public int getSpotSide(java.lang.String positionText)

Get the side of the piece currently occupying the given spot.

Parameters:

positionText - text notation describing a spot.

Returns:

side index (0 or 1) or NO_SIDE if the spot is unoccupied.

See Also:

getMove(String positionText)

getSpot

public static int getSpot(java.lang.String positionText)

Get the spot indicated by the given textPosition.

Parameters:

positionText - text notation describing a spot.

Returns:

spot index or NO_SPOT if positionText is invalid.

See Also:

getMove(String positionText)

getSpotCoordinate

public static int getSpotCoordinate(int spot,
                                    int axis)

Return an a or b cartesian coordinate for the given board spot. Spots are formed by the intersection of two board rows and they occupy a grid bounded by (0,0) and (6,6). There are three spots per row. UI clients may use spot coordinates to assign locations to various board spots on screen. A,B coordinate mapping to the screen is left up to the UI client.

Parameters:

spot - 0 based index identifying a spot on the board.

axis - AXIS_A or AXIS_B.

Returns:

a scalar coordinate.

See Also:

N_SPOTS, AXIS_A, AXIS_B

getSpotCoordinate

public static int getSpotCoordinate(int row,
                                    int spot,
                                    int axis)

Return an a or b cartesian coordinate for the given row spot.

Parameters:

row - 0 based index identifying a row of 3 spots.

spot - one of ROW_SPOT_0, ROW_SPOT_1, ROW_SPOT_2.

axis - AXIS_A or AXIS_B.

Returns:

a scalar coordinate.

See Also:

getSpotCoordinate(int spot, int axis), N_ROWS, ROW_SPOT_0, ROW_SPOT_1, ROW_SPOT_2, AXIS_A, AXIS_B

getSpot

public static int getSpot(int coordinateA,
                          int coordinateB)

Return the intersection spot index at coordinate a,b.

Parameters:

coordinateA - coordinate on the board A axis.

coordinateB - coordinate on the board B axis.

Returns:

spot index or NO_SPOT if there is no spot at a,b.

isValidMove

public boolean isValidMove(MillMove move)

Return true if the given move is valid given the board state. This routine leaves the move iterator in an undefined state.

isTaking

public boolean isTaking()

Return true if the current move is a taking move.

isTakingAny

public boolean isTakingAny()

Return true if the player can take even from a mill.

isTranslating

public boolean isTranslating()

Return true if the current move is a sliding or flying move.

isPlacing

public boolean isPlacing()

Return true if the current move is a placing move.

isSliding

public boolean isSliding()

Return true if the current move is a sliding move.

isFlying

public boolean isFlying()

Return true if the current move is a flying move.

getMenOut

public int getMenOut(int side)

Return the number of men taken from the given side.