CloseableIterable.java

/*
 * Copyright 2019 SPF4J.
 *
 * 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.spf4j.base;

import edu.umd.cs.findbugs.annotations.CleanupObligation;
import edu.umd.cs.findbugs.annotations.DischargesObligation;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import java.io.Closeable;
import java.util.Iterator;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;

/**
 * need to extend java.io.Closeable so that jaxrs does not interfere.
 * @author Zoltan Farkas
 */
@CleanupObligation
public interface CloseableIterable<T> extends Closeable, Iterable<T> {

  @DischargesObligation
  void close();

  static <T> CloseableIterable<T> from(final CloseableIterator<T> iterator) {
    return new CloseableIterable<T>() {
      @Override
      public void close() {
        iterator.close();
      }

      @Override
      public Iterator<T> iterator() {
        return iterator;
      }

    };
  }

  static <T> CloseableIterable<T> from(final Iterable<T> it) {
    return from(it, () -> { });
  }


  static <T> CloseableIterable<T> from(final Iterable<T> it, final AutoCloseable close) {
    return new CloseableIterable<T>() {
      @Override
      @SuppressFBWarnings("EXS_EXCEPTION_SOFTENING_NO_CHECKED")
      public void close() {
        try {
          close.close();
        } catch (RuntimeException | Error e) {
          throw e;
        } catch (Exception ex) {
          throw new RuntimeException(ex);
        }
      }

      @Override
      public Iterator<T> iterator() {
        return it.iterator();
      }
    };
  }

  default Stream<T> toStream() {
    return toStream(false);
  }

  default Stream<T> toStream(final boolean parallel) {
    return StreamSupport.stream(spliterator(), parallel).onClose(() -> this.close());
  }

}