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 *    any, must include the following acknowledgement:
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package org.apache.commons.collections.functors;

import java.util.Collection;
import java.util.Iterator;

import org.apache.commons.collections.Closure;
import org.apache.commons.collections.Predicate;
import org.apache.commons.collections.Transformer;

/**
 * Internal utilities for functors.
 * 
 * @since Commons Collections 3.0
 * @version $Revision: 1.1 $ $Date: 2004/01/16 18:51:59 $
 *
 * @author Stephen Colebourne
 */
class FunctorUtils {
    
    /**
     * Restricted constructor.
     */
    private FunctorUtils() {
    }
    
    /**
     * Clone the predicates to ensure that the internal reference can't be messed with.
     * 
     * @param predicates  the predicates to copy
     * @return the cloned predicates
     */
    static Predicate[] copy(Predicate[] predicates) {
        if (predicates == null) {
            return null;
        }
        return (Predicate[]) predicates.clone();
    }
    
    /**
     * Validate the predicates to ensure that all is well.
     * 
     * @param predicates  the predicates to validate
     */
    static void validate(Predicate[] predicates) {
        if (predicates == null) {
            throw new IllegalArgumentException("The predicate array must not be null");
        }
        for (int i = 0; i < predicates.length; i++) {
            if (predicates[i] == null) {
                throw new IllegalArgumentException("The predicate array must not contain a null predicate, index " + i + " was null");
            }
        }
    }
    
    /**
     * Validate the predicates to ensure that all is well.
     * 
     * @param predicates  the predicates to validate
     */
    static void validateMin2(Predicate[] predicates) {
        if (predicates == null) {
            throw new IllegalArgumentException("The predicate array must not be null");
        }
        if (predicates.length < 2) {
            throw new IllegalArgumentException(
                "At least 2 predicates must be specified in the predicate array, size was " + predicates.length);
        }
        for (int i = 0; i < predicates.length; i++) {
            if (predicates[i] == null) {
                throw new IllegalArgumentException("The predicate array must not contain a null predicate, index " + i + " was null");
            }
        }
    }

    /**
     * Validate the predicates to ensure that all is well.
     * 
     * @param predicates  the predicates to validate
     * @return predicate array
     */
    static Predicate[] validate(Collection predicates) {
        if (predicates == null) {
            throw new IllegalArgumentException("The predicate collection must not be null");
        }
        if (predicates.size() < 2) {
            throw new IllegalArgumentException(
                "At least 2 predicates must be specified in the predicate collection, size was " + predicates.size());
        }
        // convert to array like this to guarantee iterator() ordering
        Predicate[] preds = new Predicate[predicates.size()];
        int i = 0;
        for (Iterator it = predicates.iterator(); it.hasNext();) {
            preds[i] = (Predicate) it.next();
            if (preds[i] == null) {
                throw new IllegalArgumentException("The predicate collection must not contain a null predicate, index " + i + " was null");
            }
            i++;
        }
        return preds;
    }
    
    /**
     * Clone the closures to ensure that the internal reference can't be messed with.
     * 
     * @param closures  the closures to copy
     * @return the cloned closures
     */
    static Closure[] copy(Closure[] closures) {
        if (closures == null) {
            return null;
        }
        return (Closure[]) closures.clone();
    }
    
    /**
     * Validate the closures to ensure that all is well.
     * 
     * @param closures  the closures to validate
     */
    static void validate(Closure[] closures) {
        if (closures == null) {
            throw new IllegalArgumentException("The closure array must not be null");
        }
        for (int i = 0; i < closures.length; i++) {
            if (closures[i] == null) {
                throw new IllegalArgumentException("The closure array must not contain a null closure, index " + i + " was null");
            }
        }
    }

    /**
     * Copy method
     * 
     * @param transformers  the transformers to copy
     */
    static Transformer[] copy(Transformer[] transformers) {
        if (transformers == null) {
            return null;
        }
        return (Transformer[]) transformers.clone();
    }
    
    /**
     * Validate method
     * 
     * @param transformers  the transformers to validate
     */
    static void validate(Transformer[] transformers) {
        if (transformers == null) {
            throw new IllegalArgumentException("The transformer array must not be null");
        }
        for (int i = 0; i < transformers.length; i++) {
            if (transformers[i] == null) {
                throw new IllegalArgumentException(
                    "The transformer array must not contain a null transformer, index " + i + " was null");
            }
        }
    }

}
