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/*
 * Copyright 2011,2012 Metamarkets Group Inc.
 *
 * 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 com.metamx.common.guava.nary;

import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 */
public class BinaryTransformIterator implements Iterator
{
  public static  BinaryTransformIterator create(
      Iterator lhs,
      Iterator rhs,
      BinaryFn fn
  )
  {
    return new BinaryTransformIterator(lhs, rhs, fn);
  }

  private final Iterator lhsIter;
  private final Iterator rhsIter;
  private final BinaryFn binaryFn;

  public BinaryTransformIterator(Iterator lhsIter, Iterator rhsIter, BinaryFn binaryFn)
  {
    this.lhsIter = lhsIter;
    this.rhsIter = rhsIter;
    this.binaryFn = binaryFn;
  }

  @Override
  public boolean hasNext()
  {
    return lhsIter.hasNext() || rhsIter.hasNext();
  }

  @Override
  public RetType next()
  {
    if (!hasNext()) {
      throw new NoSuchElementException();
    }

    return binaryFn.apply(
        lhsIter.hasNext() ? lhsIter.next() : null,
        rhsIter.hasNext() ? rhsIter.next() : null
    );
  }

  @Override
  public void remove()
  {
    throw new UnsupportedOperationException();
  }
}