com.metamx.common.guava.FunctionalIterator Maven / Gradle / Ivy

/*
 * 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;

import com.google.common.base.Function;
import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.collect.Iterators;
import com.metamx.common.guava.nary.BinaryFn;
import com.metamx.common.guava.nary.BinaryTransformIterator;
import com.metamx.common.guava.nary.TrinaryFn;
import com.metamx.common.guava.nary.TrinaryTransformIterator;

import java.util.Iterator;

/**
 */
public class FunctionalIterator implements Iterator
{
  private final Iterator delegate;

  public static  FunctionalIterator create(Iterator delegate)
  {
    return new FunctionalIterator<>(delegate);
  }

  public static  FunctionalIterator fromConcatenation(Iterator... toConcat)
  {
    return new FunctionalIterator<>(Iterators.concat(toConcat));
  }

  public static  FunctionalIterator fromConcatenation(Iterator> toConcat)
  {
    return new FunctionalIterator<>(Iterators.concat(toConcat));
  }

  public FunctionalIterator(
      Iterator delegate
  )
  {
    this.delegate = delegate;
  }

  public boolean hasNext()
  {
    return delegate.hasNext();
  }

  public T next()
  {
    return delegate.next();
  }

  public void remove()
  {
    delegate.remove();
  }

  public  FunctionalIterator transform(Function fn)
  {
    return new FunctionalIterator<>(Iterators.transform(delegate, fn));
  }

  public  FunctionalIterator transformCat(Function> fn)
  {
    return new FunctionalIterator<>(Iterators.concat(Iterators.transform(delegate, fn)));
  }

  public  FunctionalIterator keep(Function fn)
  {
    return new FunctionalIterator<>(Iterators.filter(Iterators.transform(delegate, fn), Predicates.notNull()));
  }

  public FunctionalIterator filter(Predicate pred)
  {
    return new FunctionalIterator<>(Iterators.filter(delegate, pred));
  }

  public FunctionalIterator drop(int numToDrop)
  {
    return new FunctionalIterator<>(new DroppingIterator<>(delegate, numToDrop));
  }

  public FunctionalIterator limit(int limit)
  {
    return new FunctionalIterator<>(Iterators.limit(delegate, limit));
  }

  public FunctionalIterator concat(Iterator... toConcat)
  {
    if (toConcat.length == 1) {
      return new FunctionalIterator<>(Iterators.concat(delegate, toConcat[0]));
    }
    return new FunctionalIterator<>(Iterators.concat(delegate, Iterators.concat(toConcat)));
  }

  public FunctionalIterator concat(Iterator> toConcat)
  {
    return new FunctionalIterator<>(Iterators.concat(delegate, Iterators.concat(toConcat)));
  }

  public  FunctionalIterator binaryTransform(
      final Iterator otherIterator, final BinaryFn binaryFn
  )
  {
    return new FunctionalIterator<>(BinaryTransformIterator.create(delegate, otherIterator, binaryFn));
  }

  public  FunctionalIterator trinaryTransform(
      final Iterator iterator1,
      final Iterator iterator2,
      final TrinaryFn trinaryFn
  )
  {
    return new FunctionalIterator<>(TrinaryTransformIterator.create(delegate, iterator1, iterator2, trinaryFn));
  }
}