NullSequence.java

package jetbrains.mps.internal.collections.runtime.impl;

/*Generated by MPS */

import jetbrains.mps.internal.collections.runtime.Sequence;
import jetbrains.mps.internal.collections.runtime.ISequence;
import java.util.Iterator;
import java.util.NoSuchElementException;

public class NullSequence<T> extends Sequence<T> implements Iterable<T> {
  private static final NullSequence<Object> INSTANCE = new NullSequence<Object>();
  protected NullSequence() {
  }
  @Override
  public T first() {
    return null;
  }
  @Override
  public T last() {
    return null;
  }
  @Override
  public ISequence<T> cut(int length) {
    return this;
  }
  @Override
  public ISequence<T> skip(int length) {
    return this;
  }
  @Override
  public ISequence<T> tail(int length) {
    return this;
  }
  @Override
  public ISequence<T> take(int length) {
    return this;
  }
  @Override
  public ISequence<T> page(int skip, int skipplustake) {
    return this;
  }
  @Override
  public Iterator<T> iterator() {
    return new NullSequence.EmptyIterator<T>();
  }
  @SuppressWarnings(value = "unchecked")
  public static <U> NullSequence<U> instance() {
    return (NullSequence<U>) INSTANCE;
  }
  protected static class EmptyIterator<U> implements Iterator<U> {
    protected EmptyIterator() {
    }
    @Override
    public boolean hasNext() {
      return false;
    }
    @Override
    public U next() {
      throw new NoSuchElementException();
    }
    @Override
    public void remove() {
      throw new UnsupportedOperationException();
    }
  }
}