    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.io.function;
    019
    020import java.io.IOException;
    021import java.io.UncheckedIOException;
    022import java.util.Iterator;
    023import java.util.NoSuchElementException;
    024import java.util.Objects;
    025import java.util.function.Consumer;
    026
    027/**
    028 * Like {@link Iterator} but throws {@link IOException}.
    029 *
    030 * @param <E> the type of elements returned by this iterator.
    031 * @since 2.12.0
    032 */
    033public interface IOIterator<E> {
    034
    035    /**
    036     * Adapts the given Iterable as an IOIterator.
    037     *
    038     * @param <E> the type of the stream elements.
    039     * @param iterable The iterable to adapt
    040     * @return A new IOIterator
    041     * @since 2.17.0
    042     */
    043    static <E> IOIterator<E> adapt(final Iterable<E> iterable) {
    044        return IOIteratorAdapter.adapt(iterable.iterator());
    045    }
    046
    047    /**
    048     * Adapts the given Iterator as an IOIterator.
    049     *
    050     * @param <E> the type of the stream elements.
    051     * @param iterator The iterator to adapt
    052     * @return A new IOIterator
    053     */
    054    static <E> IOIterator<E> adapt(final Iterator<E> iterator) {
    055        return IOIteratorAdapter.adapt(iterator);
    056    }
    057
    058    /**
    059     * Creates an {@link Iterator} for this instance that throws {@link UncheckedIOException} instead of
    060     * {@link IOException}.
    061     *
    062     * @return an {@link UncheckedIOException} {@link Iterator}.
    063     */
    064    default Iterator<E> asIterator() {
    065        return new UncheckedIOIterator<>(this);
    066    }
    067
    068    /**
    069     * Like {@link Iterator#forEachRemaining(Consumer)}.
    070     *
    071     * @param action See delegate.
    072     * @throws IOException if an I/O error occurs.
    073     */
    074    default void forEachRemaining(final IOConsumer<? super E> action) throws IOException {
    075        Objects.requireNonNull(action);
    076        while (hasNext()) {
    077            action.accept(next());
    078        }
    079    }
    080
    081    /**
    082     * Like {@link Iterator#hasNext()}.
    083     *
    084     * @return See delegate.
    085     * @throws IOException if an I/O error occurs.
    086     */
    087    boolean hasNext() throws IOException;
    088
    089    /**
    090     * Like {@link Iterator#next()}.
    091     *
    092     * @return See delegate.
    093     * @throws IOException if an I/O error occurs.
    094     * @throws NoSuchElementException if the iteration has no more elements
    095     */
    096    E next() throws IOException;
    097
    098    /**
    099     * Like {@link Iterator#remove()}.
    100     *
    101     * @throws IOException if an I/O error occurs.
    102     */
    103    @SuppressWarnings("unused")
    104    default void remove() throws IOException {
    105        unwrap().remove();
    106    }
    107
    108    /**
    109     * Unwraps this instance and returns the underlying {@link Iterator}.
    110     * <p>
    111     * Implementations may not have anything to unwrap and that behavior is undefined for now.
    112     * </p>
    113     * @return the underlying Iterator.
    114     */
    115    Iterator<E> unwrap();
    116
    117}