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package org.apache.commons.collections.functors;

import java.io.Serializable;
import java.util.Collection;

import org.apache.commons.collections.Predicate;

/**
 * Predicate implementation that returns true if only one of the predicates return true.
 * 
 * @since Commons Collections 3.0
 * @version $Revision: 2094 $ $Date: 2004-01-17 03:55:12 +0900 (Sat, 17 Jan 2004) $
 *
 * @author Stephen Colebourne
 */
public final class OnePredicate implements Predicate, Serializable {

    /** Serial version UID */
    static final long serialVersionUID = -8125389089924745785L;
    
    /** The array of predicates to call */
    private final Predicate[] iPredicates;
    
    /**
     * Factory to create the predicate.
     * 
     * @param predicates  the predicates to check, cloned, not null
     * @return the <code>any</code> predicate
     * @throws IllegalArgumentException if the predicates array is null
     * @throws IllegalArgumentException if the predicates array has less than 2 elements
     * @throws IllegalArgumentException if any predicate in the array is null
     */
    public static Predicate getInstance(Predicate[] predicates) {
        FunctorUtils.validateMin2(predicates);
        predicates = FunctorUtils.copy(predicates);
        return new OnePredicate(predicates);
    }

    /**
     * Factory to create the predicate.
     * 
     * @param predicates  the predicates to check, cloned, not null
     * @return the <code>one</code> predicate
     * @throws IllegalArgumentException if the predicates array is null
     * @throws IllegalArgumentException if any predicate in the array is null
     * @throws IllegalArgumentException if the predicates array has less than 2 elements
     */
    public static Predicate getInstance(Collection predicates) {
        Predicate[] preds = FunctorUtils.validate(predicates);
        return new OnePredicate(preds);
    }

    /**
     * Constructor that performs no validation.
     * Use <code>getInstance</code> if you want that.
     * 
     * @param predicates  the predicates to check, not cloned, not null
     */
    public OnePredicate(Predicate[] predicates) {
        super();
        iPredicates = predicates;
    }

    /**
     * Return the predicate result.
     */
    public boolean evaluate(Object object) {
        boolean match = false;
        for (int i = 0; i < iPredicates.length; i++) {
            if (iPredicates[i].evaluate(object)) {
                if (match) {
                    return false;
                }
                match = true;
            }
        }
        return match;
    }
    
}
