CollectionIterator.java

package org.gjt.sp.jedit.bsh.collection;

import java.util.Iterator;
import java.util.Collection;
//import java.util.Map;

/**
 *	This is the implementation of:
 *	BshIterator - a dynamically loaded extension that supports the collections
 *	API supported by JDK1.2 and greater.
 *
 *	@author Daniel Leuck
 *	@author Pat Niemeyer
 */
public class CollectionIterator implements org.gjt.sp.jedit.bsh.BshIterator
{
    private Iterator iterator;

    /**
     * Construct a basic CollectionIterator
     *
     * @param iterateOverMe The object over which we are iterating
     *
     * @throws java.lang.IllegalArgumentException If the argument is not a
     * supported (i.e. iterable) type.
     *
     * @throws java.lang.NullPointerException If the argument is null
     */
    public CollectionIterator(Object iterateOverMe) {
        iterator = createIterator(iterateOverMe);
    }

    /**
     * Create an iterator over the given object
     *
     * @param iterateOverMe Object of type Iterator, Collection, or types
     * supported by CollectionManager.BasicBshIterator
     *
     * @return an Iterator
     *
     * @throws java.lang.IllegalArgumentException If the argument is not a
     * supported (i.e. iterable) type.
     *
     * @throws java.lang.NullPointerException If the argument is null
     */
    protected Iterator createIterator(Object iterateOverMe)
    {
        if (iterateOverMe==null)
            throw new NullPointerException("Object arguments passed to " +
                "the CollectionIterator constructor cannot be null.");

        if (iterateOverMe instanceof Iterator)
            return (Iterator)iterateOverMe;

        if (iterateOverMe instanceof Collection)
            return ((Collection)iterateOverMe).iterator();

        /*
        Should we be able to iterate over maps?
        if (iterateOverMe instanceof Map)
            return ((Map)iterateOverMe).entrySet().iterator();
        */

        throw new IllegalArgumentException(
            "Cannot enumerate object of type "+iterateOverMe.getClass());
    }

    /**
     * Fetch the next object in the iteration
     *
     * @return The next object
     */
    public Object next() {
        return iterator.next();
    }

    /**
     * Returns true if and only if there are more objects available
     * via the <code>next()</code> method
     *
     * @return The next object
     */
    public boolean hasNext() {
        return iterator.hasNext();
    }
}