com.barrybecker4.game.twoplayer.go.board.elements.position.GoBoardPosition Maven / Gradle / Ivy

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/** Copyright by Barry G. Becker, 2000-2011. Licensed under MIT License: http://www.opensource.org/licenses/MIT  */
package com.barrybecker4.game.twoplayer.go.board.elements.position;

import com.barrybecker4.common.format.FormatUtil;
import com.barrybecker4.game.common.board.BoardPosition;
import com.barrybecker4.game.twoplayer.go.board.GoBoard;
import com.barrybecker4.game.twoplayer.go.board.elements.IGoMember;
import com.barrybecker4.game.twoplayer.go.board.elements.eye.IGoEye;
import com.barrybecker4.game.twoplayer.go.board.elements.group.IGoGroup;
import com.barrybecker4.game.twoplayer.go.board.elements.string.IGoString;

/**
 * The GoBoardPosition describes the physical marker at a location on the board.
 * It can be empty or occupied. If occupied, then it is  either black or white and has a string owner.
 * A GoBoardPosition may have an eye owner if it is part of a group's eye.
 *
 * @author Barry Becker
 */
public final class GoBoardPosition extends BoardPosition
                                   implements IGoMember {

    /** the string (connected set of stones) to which this stone belongs. */
    private IGoString string_;

    /**
     * if non-null then this position belongs to an eye string.
     * The group owner of the eye is different than the owner of the string.
     */
    private IGoEye eye_;

    /**
     * when true the stone has been visited already during a search.
     * This is a temporary state that is used for some traversal operations.
     */
    private boolean visited_;

    /** the amount this position contributes to the overall score.  */
    private double scoreContribution_ = 0.0;


    /**
     * create a new go stone.
     * @param row location.
     * @param col location.
     * @param string the string that this stone belongs to.
     * @param stone the stone at this position if there is one (use null if no stone).
     */
    public GoBoardPosition( int row, int col, IGoString string, GoStone stone) {
        super( row, col, stone );
        string_ = string;
        eye_ = null;
        visited_ = false;
    }

    /**
     * Create a deep copy of this position.
     */
    public GoBoardPosition(GoBoardPosition pos) {
        this( pos.location_.getRow(), pos.location_.getCol(), pos.string_,
              (pos.piece_ == null) ? null : (GoStone)pos.piece_.copy());
        pos.setEye(getEye());
        setVisited(pos.isVisited());
    }

    /**
     * @return copy of this position.
     */
    @Override
    public GoBoardPosition copy() {
        return new GoBoardPosition(this);
    }

    /**
     * @param string  the string owner we are assign to this stone.
     */
    public void setString( IGoString string ) {
        string_ = string;
    }

    /**
     * @return  the string owner for this stone.
     * There may be none if its blank and part of an eye, in that case null is returned.
     */
    public IGoString getString() {
        return string_;
    }

    /**
     * @return the group owner.
     * There is only one group owner that has the same ownership (color) as this stone.
     * The stone may also belong to to an eye in an opponent group, however.
     */
    public IGoGroup getGroup() {
        if (string_ != null)
            return string_.getGroup();
        if (eye_ != null) {
            return eye_.getGroup();
        }
        return null;
    }

    /**
     * @param eye the eye owner this space is to be assigned to
     */
    public void setEye(IGoEye eye ) {
        eye_ = eye;
    }

    /**
     * @return  the eye that this space belongs to. May be null if no eye owner.
     */
    public IGoEye getEye() {
        return eye_;
    }

    /**
     *
     * @return  true if the string this stone belongs to is in atari
     */
    public boolean isInAtari(GoBoard b) {
       return (getString() != null && getString().getNumLiberties(b) == 1);
    }


    public void setVisited( boolean visited ) {
        visited_ = visited;
    }

    public boolean isVisited() {
        return visited_;
    }

    /**
     * @return  true if this position is part of an eye.
     */
    public boolean isInEye() {
        return eye_!=null;
    }

    /**
     * we must recalculate the number of liberties every time because it changes often.
     * @return the number of liberties the specified position has.
     */
    public int getNumLiberties( GoBoard board ) {
        int numLiberties = 0;
        int row = getRow();
        int col = getCol();
        if ( row > 1 && board.getPosition( row - 1, col ).isUnoccupied() )
            numLiberties++;
        if ( row < board.getNumRows() && board.getPosition( row + 1, col ).isUnoccupied() )
            numLiberties++;
        if ( col > 1 && board.getPosition( row, col - 1 ).isUnoccupied() )
            numLiberties++;
        if ( col < board.getNumCols() && board.getPosition( row, col + 1 ).isUnoccupied() )
            numLiberties++;

        return numLiberties;
    }

     /**
      * make it show an empty board position.
      */
    public void clear(GoBoard board) {
        IGoString string = getString();

        if (string != null)  {
            string.remove(this, board);
        } else {
            assert isUnoccupied();
        }
        clear();
    }

    /**
     * make it show an empty board position.
     */
    @Override
    public void clear() {
        super.clear();
        setString(null);
        setEye(null);
        scoreContribution_ = 0;
        setVisited(false);
    }

    /**
     * @return a string representation of the go board position
     */
    @Override
    public String getDescription() {
        return super.getDescription()+ " score:"+ FormatUtil.formatNumber(scoreContribution_);
    }

    /**
     * @return a string representation of the go board position
     */
    @Override
    public String toString() {
        return super.toString()+ " s:"+ FormatUtil.formatNumber(scoreContribution_) + " hc:"+hashCode();
    }

    public double getScoreContribution() {
        return scoreContribution_;
    }

    public void setScoreContribution(double scoreContribution) {
        this.scoreContribution_ = scoreContribution;
    }
}