Tuple.java

package crossnum;

import java.util.ArrayList;
import java.util.List;

/**
 * Represents a list of variable values that must sum to some required value.
 *
 * @author dub_nerd
 *
 */
public class Tuple {

    /**
     * List of variables.
     */
    private List<Variable> variables = new ArrayList<Variable>();

    /**
     * The required sum.
     */
    private int requiredSum;

    /**
     * Lock variables so that they are "owned" by this tuple. Anything not
     * already locked becomes locked.
     *
     * @return the number of locks obtained.
     */
    int lock() {
        int locks = 0;
        for (Variable v : variables()) {
            if (!v.isLocked()) {
                v.lock(this);
                locks++;
            }
        }
        return locks;
    }


    /**
     * Unlock variables "owned" by this tuple.
     *
     * @return the number of locks released.
     */
    int unlock() {
        int locks = 0;
        for (Variable v : variables()) {
            if (v.getLock() == this) {
                v.lock(null);
                locks++;
            }
        }
        return locks;
    }


    /**
     * Return the number of variables in tuple which are not yet locked
     * @return number unlocked
     */
    int getNumUnlocked() {
        return (int)variables.stream().filter(v -> !v.isLocked()).count();
    }


    /**
     * Get the value to which all the remaining unlocked unknowns must sum.
     * @return remainder sum
     */
    int getRemainderSum() {

        // Get the total of all our unknowns that are already locked
        int lockedTotal = variables().stream().filter(v -> v.isLocked())
                .mapToInt(v -> v.getValue()).sum();

        // Subtract from total required sum to get remainder sum
        int remainderSum = getRequiredSum() - lockedTotal;
        return remainderSum;
    }

    // Other accessor methods

    public List<Variable> variables() {
        return variables;
    }


    public int getRequiredSum() {
        return requiredSum;
    }


    public void setRequiredSum(int requiredSum) {
        this.requiredSum = requiredSum;
    }

}