ThunkIterator.java

/***************************************************************************
   Copyright 2014 Emily Estes

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
***************************************************************************/
package net.metanotion.functor;


import java.util.Iterator;

/** An iterator instance which produces values by repeatedly evaluating a provided thunk.
	@param <E> The type of elements produced by this iterator and provided by the thunk.
*/
public final class ThunkIterator<E> implements Iterator<E> {
	private final Thunk<E> f;

	/** Produce a new iterator whose output is the result of evaluating the provided thunk.
		@param f The thunk which produces the output of this iterator.
	*/
	public ThunkIterator(final Thunk<E> f) { this.f = f; }

	@Override public boolean hasNext() { return true; }

	@Override public E next() {
		try {
			return f.eval();
		} catch (final Exception e) {
			throw new RuntimeException(e);
		}
	}

	@Override public void remove() { throw new UnsupportedOperationException(); }
}