net.sf.staccatocommons.collections.stream.internal.algorithms.DropWhileStream Maven / Gradle / Ivy

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/**
 *  Copyright (c) 2010-2012, The StaccatoCommons Team
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation; version 3 of the License.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 */


package net.sf.staccatocommons.collections.stream.internal.algorithms;

import net.sf.staccatocommons.collections.stream.AbstractStream;
import net.sf.staccatocommons.collections.stream.Stream;
import net.sf.staccatocommons.defs.Evaluable;
import net.sf.staccatocommons.iterators.PrependThriterator;
import net.sf.staccatocommons.iterators.thriter.Thriterator;
import net.sf.staccatocommons.iterators.thriter.Thriterators;
import net.sf.staccatocommons.restrictions.check.NonNull;

/**
 * @author flbulgarelli
 * 
 */
public class DropWhileStream extends AbstractStream {
  private final Evaluable predicate;
  private Stream source;
  private Thriterator iter;
  
  /**
   * Creates a new {@link TakeWhileStream}
   */
  public DropWhileStream(@NonNull Stream stream, @NonNull Evaluable predicate) {
    this.source = stream;
    this.predicate = predicate;
  }

  public Thriterator iterator() {
    if (iter == null) {
      iter = source.iterator();
      A next = null;
      while (iter.hasNext() && predicate.eval(next = iter.next())) {
        next = null;
      }
      if (next == null)
        iter = Thriterators.from(iter);
      else
        iter = new PrependThriterator(next, iter);
    }
    return iter;

  }
}