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/*
 * Copyright 2016 Daniel Skogquist Åborg
 *
 * 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.d2ab.collection;

import org.d2ab.iterator.ChainingIterator;
import org.d2ab.iterator.MappingIterator;

import java.util.Iterator;
import java.util.function.Function;

public class ChainingIterable implements Iterable {
	private final Iterable> iterables;

	public ChainingIterable(Iterable> iterables) {
		this.iterables = iterables;
	}

	public static  Iterable empty() {
		return new ChainingIterable<>(Iterables.empty());
	}

	@SafeVarargs
	public static  Iterable concat(Iterable... iterables) {
		return new ChainingIterable<>(Iterables.of(iterables));
	}

	public static  Iterable concatAny(Iterable containers) {
		return flatten(containers, Iterables::from);
	}

	public static  Iterable flatten(Iterable iterable,
	                                         Function> mapper) {
		return new ChainingIterable<>(() -> new MappingIterator<>(iterable.iterator(), mapper));
	}

	@Override
	public Iterator iterator() {
		return new ChainingIterator<>(iterables);
	}
}