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/*
 * Generated - testing becomes easier
 *
 * Copyright (C) 2020 [email protected]
 *
 * 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 org.genthz.util;

import java.util.Objects;
import java.util.Spliterator;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.stream.StreamSupport;

/**
 * Util class.
 *
 * @author mathter
 * @version 1.0.0
 * @since 1.0.0
 */
public final class StreamUtil {

    private StreamUtil() {
    }

    /**
     * Create {@linkplain java.util.stream.Stream} for startElement and generating function next.
     *
     * @param startElement start element of the stream.
     * @param next         generation function.
     * @param           type of the objects.
     * @return stream of objects.
     */
    public static final  java.util.stream.Stream of(T startElement, Function next) {
        return StreamSupport.stream(new NextSpliterator(startElement, next), false);
    }

    private static final class NextSpliterator implements Spliterator {
        private final Function next;
        private T element;

        public NextSpliterator(T element, Function next) {
            this.element = Objects.requireNonNull(element);
            this.next = Objects.requireNonNull(next);
        }

        @Override
        public boolean tryAdvance(Consumer action) {
            if (this.element != null) {
                Objects.requireNonNull(action).accept(this.element);
                this.element = this.next.apply(this.element);

                return true;
            }

            return false;
        }

        @Override
        public Spliterator trySplit() {
            return null;
        }

        @Override
        public long estimateSize() {
            return Long.MAX_VALUE;
        }

        @Override
        public int characteristics() {
            return NONNULL & IMMUTABLE & SIZED & CONCURRENT;
        }
    }
}