/*
    * Copyright (C) 2012 The Guava Authors
    *
    * 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.google.common.collect;
  
  import static com.google.common.base.Preconditions.checkNotNull;
  
  import com.google.common.annotations.GwtCompatible;
  
  import java.util.Iterator;
  
  /**
   * An iterator that transforms a backing iterator; for internal use. This avoids
   * the object overhead of constructing a {@link Function} for internal methods.
   *
   * @author Louis Wasserman
   */
  @GwtCompatible
  abstract class TransformedIterator<F, T> implements Iterator<T> {
    final Iterator<? extends F> backingIterator;
  
    TransformedIterator(Iterator<? extends F> backingIterator) {
      this.backingIterator = checkNotNull(backingIterator);
    }
  
    abstract T transform(F from);
  
    @Override
    public final boolean hasNext() {
      return backingIterator.hasNext();
    }
  
    @Override
    public final T next() {
      return transform(backingIterator.next());
    }
  
    @Override
    public final void remove() {
      backingIterator.remove();
    }
  }