/** Copyright by Barry G. Becker, 2000-2011. Licensed under MIT License: http://www.opensource.org/licenses/MIT */
package com.barrybecker4.game.twoplayer.go.board.move;
import com.barrybecker4.common.geometry.ByteLocation;
import com.barrybecker4.common.geometry.Location;
import com.barrybecker4.game.twoplayer.common.TwoPlayerMove;
import com.barrybecker4.game.twoplayer.go.board.GoBoard;
import com.barrybecker4.game.twoplayer.go.board.analysis.neighbor.NeighborAnalyzer;
import com.barrybecker4.game.twoplayer.go.board.analysis.neighbor.NeighborType;
import com.barrybecker4.game.twoplayer.go.board.elements.position.GoBoardPosition;
import com.barrybecker4.game.twoplayer.go.board.elements.position.GoBoardPositionSet;
import com.barrybecker4.game.twoplayer.go.board.elements.position.GoStone;
import com.barrybecker4.game.twoplayer.go.board.elements.string.GoStringSet;
import com.barrybecker4.game.twoplayer.go.board.elements.string.IGoString;
import java.util.Iterator;
/**
* Describes a change in state from one board
* position to the next in a Go game.
*
* @author Barry Becker
*/
public class GoMove extends TwoPlayerMove {
/**
* A linked list of the pieces that were captured with this move.
* null if there were no captures.
*/
private GoCaptureList captureList_ = null;
/**
* Constructor.
*/
public GoMove( Location destination, int val, GoStone stone ) {
super(destination, val, stone );
}
/** Copy constructor */
protected GoMove(GoMove move) {
super(move);
if ( move.captureList_ != null ) {
captureList_ = move.captureList_.copy();
}
}
/**
* make a deep copy of the move object
*/
@Override
public GoMove copy() {
return new GoMove(this);
}
/**
* factory method for creating a passing move
* @return new passing move
*/
public static GoMove createPassMove(int val, boolean player1) {
GoMove m = new GoMove(new ByteLocation(1, 1), val, null );
m.isPass_ = true;
m.setPlayer1(player1);
return m;
}
/**
* factory method for creating a resignation move
* @return new resignation move
*/
public static GoMove createResignationMove(boolean player1) {
GoMove m = new GoMove( new ByteLocation(1, 1), 0, null );
m.isResignation_ = true;
m.setPlayer1(player1);
return m;
}
/**
* Check if the current move is suicidal.
* Suicidal moves (ones that kill your own pieces) are illegal.
* Usually a move is suicidal if you play on your last liberty.
* However, if you kill an enemy string by playing on your last liberty,
* then it is legal.
* @return true if this move is suicidal.
*/
public boolean isSuicidal( GoBoard board ) {
GoBoardPosition stone = (GoBoardPosition) board.getPosition( getToRow(), getToCol() );
NeighborAnalyzer na = new NeighborAnalyzer(board);
GoBoardPositionSet nobiNbrs = na.getNobiNeighbors(stone, false, NeighborType.ANY);
GoBoardPositionSet occupiedNbrs = new GoBoardPositionSet();
for (GoBoardPosition pos : nobiNbrs) {
if (pos.isOccupied()) {
occupiedNbrs.add(pos);
}
}
return !hasLiberties(occupiedNbrs, nobiNbrs) && partOfDeadString(occupiedNbrs, board);
}
/**
* Can't be suicidal if we have a liberty.
* @return true if one or more liberties still available.
*/
private boolean hasLiberties(GoBoardPositionSet occupiedNbrs, GoBoardPositionSet nobiNbrs) {
return (nobiNbrs.size() > occupiedNbrs.size());
}
/**
* If the newly placed stone captures an opponent string, then we return false.
* @param occupiedNbrs The 4 occupied Nbrs neighbors to check
* @return true if the newly placed stone is part of a string that is now captured as a result of playing.
*/
private boolean partOfDeadString(GoBoardPositionSet occupiedNbrs, GoBoard board ) {
for (GoBoardPosition nbr : occupiedNbrs) {
if (nbr.getPiece().isOwnedByPlayer1() == this.isPlayer1()) {
// friendly string
if (nbr.getString().getNumLiberties(board) > 1) {
// can't be suicidal if a neighboring friendly string has > 1 liberty
return false;
}
}
else {
if (nbr.getString().getNumLiberties(board) == 1) {
// can't be suicidal if by playing we capture an opponent string.
return false;
}
}
}
return true;
}
/**
* It's a ko if its a single stone string, it captured exactly one stone, and it has one liberty.
* @param board the go board
* @return true if this move is part of a ko fight sequence.
*/
public boolean isKo(GoBoard board) {
if (getNumCaptures() == 1) {
//GoBoardPosition capture = (GoBoardPosition) getCaptures().getFirst();
GoBoardPosition pos = (GoBoardPosition) board.getPosition(getToLocation());
NeighborAnalyzer nbrAnal = new NeighborAnalyzer(board);
GoBoardPositionSet enemyNbrs = nbrAnal.getNobiNeighbors(pos, isPlayer1(), NeighborType.ENEMY);
int numEnemyNbrs = enemyNbrs.size();
if (numEnemyNbrs == 3
|| board.isOnEdge(pos) && numEnemyNbrs == 2
|| board.isInCorner(pos) && numEnemyNbrs == 1) {
return true;
}
}
return false;
}
/**
* returns true if the specified move caused one or more opponent groups to be in atari
*
* @return a number > 0 if the move m caused an atari. The number gives the number of stones in atari.
*/
public int numStonesAtaried(GoBoard board) {
if ( isPassingMove() )
return 0; // a pass cannot cause an atari
GoBoardPosition pos = (GoBoardPosition)board.getPosition( getToRow(), getToCol() );
NeighborAnalyzer na = new NeighborAnalyzer(board);
GoBoardPositionSet enemyNbrs = na.getNobiNeighbors( pos, NeighborType.ENEMY );
Iterator it = enemyNbrs.iterator();
int numInAtari = 0;
GoStringSet stringSet = new GoStringSet();
while ( it.hasNext() ) {
GoBoardPosition s = (GoBoardPosition) it.next();
IGoString atariedString = s.getString();
if (!stringSet.contains(atariedString) && atariedString.getNumLiberties(board) == 1 ) {
numInAtari += atariedString.size();
}
stringSet.add(atariedString); // once its in the set we won't check it again.
}
return numInAtari;
}
/**
* I would like to avoid this setter.
* @param captures captures to set. We make a defensive copy of them.
*/
public void setCaptures(GoCaptureList captures) {
captureList_ = captures.copy();
}
public GoCaptureList getCaptures() {
return captureList_;
}
public int getNumCaptures() {
if (captureList_!= null) {
return captureList_.size();
} else {
return 0;
}
}
/**
*
* @return stringified form.
*/
@Override
public String toString() {
String s = super.toString();
if ( captureList_ != null ) {
s += "num captured=" + captureList_.size();
}
return s;
}
}