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Collections library of the Staccatissimo project, focused on providing new abstractions that mix object oriented and functional programming style for dealing with iterable objects.

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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 static net.sf.staccatocommons.lang.tuple.Tuples.*;
import net.sf.staccatocommons.collections.stream.AbstractStream;
import net.sf.staccatocommons.collections.stream.Stream;
import net.sf.staccatocommons.defs.Thunk;
import net.sf.staccatocommons.defs.tuple.Tuple2;
import net.sf.staccatocommons.iterators.PrependThriterator;
import net.sf.staccatocommons.iterators.thriter.Thriterator;
import net.sf.staccatocommons.lang.thunk.Thunks;

/**
 * 
 * A {@link PrependStream} is a {@link Stream} that retrieves first a single
 * element - the head - and the elements from another {@link Iterable} - the
 * tail.
 * 
 * @author flbulgarelli
 * 
 * @param 
 */
public class PrependStream extends AbstractStream {

  private final A head;
  private final Stream source;

  /**
   * Creates a new {@link PrependStream}
   */
  public PrependStream(A head, Stream source) {
    this.source = source;
    this.head = head;
  }

  protected final Stream getSource() {
    return source;
  }

  public final int size() {
    return getSource().size() + 1;
  }

  public final boolean isEmpty() {
    return false;
  }

  public Thriterator iterator() {
    return new PrependThriterator(head(), tailIterator());
  }

  @Override
  public final Tuple2> decons() {
    return _(head(), tail());
  }

  @Override
  public Tuple2, Stream> delayedDecons() {
    return _(Thunks.constant(head), tail());
  }

  @Override
  public A head() {
    return head;
  }

  @Override
  public final Stream tail() {
    return getSource();
  }

  @Override
  public final A get(int n) {
    if (n == 0)
      return head();
    return getSource().get(n - 1);
  }

  protected final Thriterator tailIterator() {
    return getSource().iterator();
  }
}