/*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you 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 org.apache.giraph.types.ops.collections.array;

 import java.util.NoSuchElementException;

 import org.apache.giraph.function.Consumer;

 import org.apache.giraph.function.Predicate;

 import org.apache.giraph.types.ops.collections.ResettableIterator;

 /**

  * Private utilities class

  *

  * (needed since Java 7 has no default methods on interfaces,

  * and we need to extend appropriate fastutil classes)

  */

 class WArrayListPrivateUtils {

   /** Hide constructor */

   private WArrayListPrivateUtils() { }

   /**

    * Fast iterator over collection objects, which doesn't allocate new

    * element for each returned element, and can be iterated multiple times

    * using reset().

    *

    * Object returned by next() is only valid until next() is called again,

    * because it is reused.

    *

    * @param list Collection to iterate over

    * @param iterationValue reusable iteration value

    * @return RessettableIterator

    * @param <T> Element type

    */

   static <T> ResettableIterator<T> fastIterator(

       final WArrayList<T> list, final T iterationValue) {

     return new ResettableIterator<T>() {

       private int pos;

       @Override

       public boolean hasNext() {

         return pos < list.size();

       }

       @Override

       public T next() {

         if (!hasNext()) {

           throw new NoSuchElementException();

         }

         list.getIntoW(pos, iterationValue);

         pos++;

         return iterationValue;

       }

       @Override

       public void reset() {

         pos = 0;

       }

       @Override

       public void remove() {

         throw new UnsupportedOperationException();

       }

     };

   }

   /**

    * Traverse all elements of the collection, calling given function on each

    * element. Passed values are valid only during the call to the passed

    * function, so data needs to be consumed during the function.

    *

    * @param list Collection to iterate over

    * @param f Function to call on each element.

    * @param iterationValue reusable iteration value

    * @param <T> Element type

    */

   static <T> void fastForEach(

       WArrayList<T> list, Consumer<T> f, T iterationValue) {

     for (int i = 0; i < list.size(); ++i) {

       list.getIntoW(i, iterationValue);

       f.apply(iterationValue);

     }

   }

   /**

    * Traverse all elements of the collection, calling given function on each

    * element, or until predicate returns false.

    * Passed values are valid only during the call to the passed

    * function, so data needs to be consumed during the function.

    *

    * @param list Collection to iterate over

    * @param f Function to call on each element.

    * @param iterationValue reusable iteration value

    * @return true if the predicate returned true for all elements,

    *    false if it returned false for some element.

    * @param <T> Element type

    */

   static <T> boolean fastForEachWhile(

       WArrayList<T> list, Predicate<T> f, T iterationValue) {

     for (int i = 0; i < list.size(); ++i) {

       list.getIntoW(i, iterationValue);

       if (!f.apply(iterationValue)) {

         return false;

       }

     }

     return true;

   }

 }