HppcExample_002_IteratingOverDeques.java

package com.carrotsearch.hppc.examples;

import static com.carrotsearch.hppc.examples.Helpers.*;

import java.util.Iterator;

import org.junit.Before;
import org.junit.Test;

import com.carrotsearch.hppc.IntArrayDeque;
import com.carrotsearch.hppc.cursors.IntCursor;
import com.carrotsearch.hppc.procedures.IntProcedure;

/**
 * Examples of how to iterate over HPPC deques.
 */
public class HppcExample_002_IteratingOverDeques {
  
  public IntArrayDeque deque;
  
  @Before
  public void setup() {
    deque = new IntArrayDeque();
    deque.addLast(1, 1, 2, 3, 5);
  }

  /**
   * All deques implement {@link Iterable} interface that returns a "cursor"
   * object that moves over the container's elements. The cursor object remains
   * identical for the entire iteration (very little memory overhead).
   * 
   * The cursor's index points at the underlying buffer's position of a 
   * given element. 
   */
  @Test
  public void cursorFirstToLast() {
    for (IntCursor c : deque) {
      printfln("deque[%d] = %d", c.index, c.value);
    }
  }

  /**
   * Reverse order iterator (cursor).
   */
  @Test
  public void cursorLastToFirst() {
    for (Iterator<IntCursor> i = deque.descendingIterator(); i.hasNext();) {
      IntCursor c = i.next();
      printfln("deque[%d] = %d", c.index, c.value);
    }
  }

  /**
   * A for-each type loop with an anonymous class.
   */
  @Test
  public void forEachLoop() throws Exception {
    deque.forEach(new IntProcedure() {
      public void apply(int value) {
        printfln("deque[?] = %d", value);
      }
    });
  }

  /**
   * A for-each type loop with an anonymous class.
   */
  @Test
  public void forEachLoopReversed() throws Exception {
    deque.descendingForEach(new IntProcedure() {
      public void apply(int value) {
        printfln("deque[?] = %d", value);
      }
    });
  }
}