--- jsr166/src/main/java/util/PriorityQueue.java	2011/12/12 20:53:11	1.77
+++ jsr166/src/main/java/util/PriorityQueue.java	2016/11/30 18:12:52	1.114
@@ -1,12 +1,12 @@
 /*
- * Copyright (c) 2003, 2006, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.  Sun designates this
+ * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
- * by Sun in the LICENSE file that accompanied this code.
+ * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
@@ -25,6 +25,8 @@
 
 package java.util;
 
+import java.util.function.Consumer;
+
 /**
  * An unbounded priority {@linkplain Queue queue} based on a priority heap.
  * The elements of the priority queue are ordered according to their
@@ -52,18 +54,19 @@ package java.util;
  * <p>This class and its iterator implement all of the
  * <em>optional</em> methods of the {@link Collection} and {@link
  * Iterator} interfaces.  The Iterator provided in method {@link
- * #iterator()} is <em>not</em> guaranteed to traverse the elements of
+ * #iterator()} and the Spliterator provided in method {@link #spliterator()}
+ * are <em>not</em> guaranteed to traverse the elements of
  * the priority queue in any particular order. If you need ordered
  * traversal, consider using {@code Arrays.sort(pq.toArray())}.
  *
- * <p> <strong>Note that this implementation is not synchronized.</strong>
+ * <p><strong>Note that this implementation is not synchronized.</strong>
  * Multiple threads should not access a {@code PriorityQueue}
  * instance concurrently if any of the threads modifies the queue.
  * Instead, use the thread-safe {@link
  * java.util.concurrent.PriorityBlockingQueue} class.
  *
  * <p>Implementation note: this implementation provides
- * O(log(n)) time for the enqueing and dequeing methods
+ * O(log(n)) time for the enqueuing and dequeuing methods
  * ({@code offer}, {@code poll}, {@code remove()} and {@code add});
  * linear time for the {@code remove(Object)} and {@code contains(Object)}
  * methods; and constant time for the retrieval methods
@@ -75,9 +78,8 @@ package java.util;
  *
  * @since 1.5
  * @author Josh Bloch, Doug Lea
- * @param <E> the type of elements held in this collection
+ * @param <E> the type of elements held in this queue
  */
-@SuppressWarnings("unchecked")
 public class PriorityQueue<E> extends AbstractQueue<E>
     implements java.io.Serializable {
 
@@ -93,12 +95,12 @@ public class PriorityQueue<E> extends Ab
      * heap and each descendant d of n, n <= d.  The element with the
      * lowest value is in queue[0], assuming the queue is nonempty.
      */
-    private transient Object[] queue;
+    transient Object[] queue; // non-private to simplify nested class access
 
     /**
      * The number of elements in the priority queue.
      */
-    private int size = 0;
+    int size;
 
     /**
      * The comparator, or null if priority queue uses elements'
@@ -110,7 +112,7 @@ public class PriorityQueue<E> extends Ab
      * The number of times this priority queue has been
      * <i>structurally modified</i>.  See AbstractList for gory details.
      */
-    private transient int modCount = 0;
+    transient int modCount;     // non-private to simplify nested class access
 
     /**
      * Creates a {@code PriorityQueue} with the default initial
@@ -135,6 +137,19 @@ public class PriorityQueue<E> extends Ab
     }
 
     /**
+     * Creates a {@code PriorityQueue} with the default initial capacity and
+     * whose elements are ordered according to the specified comparator.
+     *
+     * @param  comparator the comparator that will be used to order this
+     *         priority queue.  If {@code null}, the {@linkplain Comparable
+     *         natural ordering} of the elements will be used.
+     * @since 1.8
+     */
+    public PriorityQueue(Comparator<? super E> comparator) {
+        this(DEFAULT_INITIAL_CAPACITY, comparator);
+    }
+
+    /**
      * Creates a {@code PriorityQueue} with the specified initial capacity
      * that orders its elements according to the specified comparator.
      *
@@ -244,8 +259,8 @@ public class PriorityQueue<E> extends Ab
             a = Arrays.copyOf(a, a.length, Object[].class);
         int len = a.length;
         if (len == 1 || this.comparator != null)
-            for (int i = 0; i < len; i++)
-                if (a[i] == null)
+            for (Object e : a)
+                if (e == null)
                     throw new NullPointerException();
         this.queue = a;
         this.size = a.length;
@@ -323,14 +338,12 @@ public class PriorityQueue<E> extends Ab
         int i = size;
         if (i >= queue.length)
             grow(i + 1);
+        siftUp(i, e);
         size = i + 1;
-        if (i == 0)
-            queue[0] = e;
-        else
-            siftUp(i, e);
         return true;
     }
 
+    @SuppressWarnings("unchecked")
     public E peek() {
         return (size == 0) ? null : (E) queue[0];
     }
@@ -391,7 +404,7 @@ public class PriorityQueue<E> extends Ab
      * @return {@code true} if this queue contains the specified element
      */
     public boolean contains(Object o) {
-        return indexOf(o) != -1;
+        return indexOf(o) >= 0;
     }
 
     /**
@@ -429,14 +442,14 @@ public class PriorityQueue<E> extends Ab
      * precise control over the runtime type of the output array, and may,
      * under certain circumstances, be used to save allocation costs.
      *
-     * <p>Suppose <tt>x</tt> is a queue known to contain only strings.
+     * <p>Suppose {@code x} is a queue known to contain only strings.
      * The following code can be used to dump the queue into a newly
-     * allocated array of <tt>String</tt>:
+     * allocated array of {@code String}:
      *
-     *  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
+     * <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
      *
-     * Note that <tt>toArray(new Object[0])</tt> is identical in function to
-     * <tt>toArray()</tt>.
+     * Note that {@code toArray(new Object[0])} is identical in function to
+     * {@code toArray()}.
      *
      * @param a the array into which the elements of the queue are to
      *          be stored, if it is big enough; otherwise, a new array of the
@@ -447,7 +460,9 @@ public class PriorityQueue<E> extends Ab
      *         this queue
      * @throws NullPointerException if the specified array is null
      */
+    @SuppressWarnings("unchecked")
     public <T> T[] toArray(T[] a) {
+        final int size = this.size;
         if (a.length < size)
             // Make a new array of a's runtime type, but my contents:
             return (T[]) Arrays.copyOf(queue, size, a.getClass());
@@ -472,7 +487,7 @@ public class PriorityQueue<E> extends Ab
          * Index (into queue array) of element to be returned by
          * subsequent call to next.
          */
-        private int cursor = 0;
+        private int cursor;
 
         /**
          * Index of element returned by most recent call to next,
@@ -492,13 +507,13 @@ public class PriorityQueue<E> extends Ab
          * We expect that most iterations, even those involving removals,
          * will not need to store elements in this field.
          */
-        private ArrayDeque<E> forgetMeNot = null;
+        private ArrayDeque<E> forgetMeNot;
 
         /**
          * Element returned by the most recent call to next iff that
          * element was drawn from the forgetMeNot list.
          */
-        private E lastRetElt = null;
+        private E lastRetElt;
 
         /**
          * The modCount value that the iterator believes that the backing
@@ -512,6 +527,7 @@ public class PriorityQueue<E> extends Ab
                 (forgetMeNot != null && !forgetMeNot.isEmpty());
         }
 
+        @SuppressWarnings("unchecked")
         public E next() {
             if (expectedModCount != modCount)
                 throw new ConcurrentModificationException();
@@ -536,7 +552,7 @@ public class PriorityQueue<E> extends Ab
                     cursor--;
                 else {
                     if (forgetMeNot == null)
-                        forgetMeNot = new ArrayDeque<E>();
+                        forgetMeNot = new ArrayDeque<>();
                     forgetMeNot.add(moved);
                 }
             } else if (lastRetElt != null) {
@@ -564,6 +580,7 @@ public class PriorityQueue<E> extends Ab
         size = 0;
     }
 
+    @SuppressWarnings("unchecked")
     public E poll() {
         if (size == 0)
             return null;
@@ -589,7 +606,8 @@ public class PriorityQueue<E> extends Ab
      * position before i. This fact is used by iterator.remove so as to
      * avoid missing traversing elements.
      */
-    private E removeAt(int i) {
+    @SuppressWarnings("unchecked")
+    E removeAt(int i) {
         // assert i >= 0 && i < size;
         modCount++;
         int s = --size;
@@ -627,6 +645,7 @@ public class PriorityQueue<E> extends Ab
             siftUpComparable(k, x);
     }
 
+    @SuppressWarnings("unchecked")
     private void siftUpComparable(int k, E x) {
         Comparable<? super E> key = (Comparable<? super E>) x;
         while (k > 0) {
@@ -640,6 +659,7 @@ public class PriorityQueue<E> extends Ab
         queue[k] = key;
     }
 
+    @SuppressWarnings("unchecked")
     private void siftUpUsingComparator(int k, E x) {
         while (k > 0) {
             int parent = (k - 1) >>> 1;
@@ -667,6 +687,7 @@ public class PriorityQueue<E> extends Ab
             siftDownComparable(k, x);
     }
 
+    @SuppressWarnings("unchecked")
     private void siftDownComparable(int k, E x) {
         Comparable<? super E> key = (Comparable<? super E>)x;
         int half = size >>> 1;        // loop while a non-leaf
@@ -685,6 +706,7 @@ public class PriorityQueue<E> extends Ab
         queue[k] = key;
     }
 
+    @SuppressWarnings("unchecked")
     private void siftDownUsingComparator(int k, E x) {
         int half = size >>> 1;
         while (k < half) {
@@ -705,10 +727,18 @@ public class PriorityQueue<E> extends Ab
     /**
      * Establishes the heap invariant (described above) in the entire tree,
      * assuming nothing about the order of the elements prior to the call.
+     * This classic algorithm due to Floyd (1964) is known to be O(size).
      */
+    @SuppressWarnings("unchecked")
     private void heapify() {
-        for (int i = (size >>> 1) - 1; i >= 0; i--)
-            siftDown(i, (E) queue[i]);
+        final Object[] es = queue;
+        final int half = (size >>> 1) - 1;
+        if (comparator == null)
+            for (int i = half; i >= 0; i--)
+                siftDownComparable(i, (E) es[i]);
+        else
+            for (int i = half; i >= 0; i--)
+                siftDownUsingComparator(i, (E) es[i]);
     }
 
     /**
@@ -727,6 +757,8 @@ public class PriorityQueue<E> extends Ab
     /**
      * Saves this queue to a stream (that is, serializes it).
      *
+     * @param s the stream
+     * @throws java.io.IOException if an I/O error occurs
      * @serialData The length of the array backing the instance is
      *             emitted (int), followed by all of its elements
      *             (each an {@code Object}) in the proper order.
@@ -745,7 +777,13 @@ public class PriorityQueue<E> extends Ab
     }
 
     /**
-     * Reconstitutes this queue from a stream (that is, deserializes it).
+     * Reconstitutes the {@code PriorityQueue} instance from a stream
+     * (that is, deserializes it).
+     *
+     * @param s the stream
+     * @throws ClassNotFoundException if the class of a serialized object
+     *         could not be found
+     * @throws java.io.IOException if an I/O error occurs
      */
     private void readObject(java.io.ObjectInputStream s)
         throws java.io.IOException, ClassNotFoundException {
@@ -765,4 +803,109 @@ public class PriorityQueue<E> extends Ab
         // spec has never explained what that might be.
         heapify();
     }
+
+    /**
+     * Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
+     * and <em>fail-fast</em> {@link Spliterator} over the elements in this
+     * queue. The spliterator does not traverse elements in any particular order
+     * (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
+     *
+     * <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
+     * {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
+     * Overriding implementations should document the reporting of additional
+     * characteristic values.
+     *
+     * @return a {@code Spliterator} over the elements in this queue
+     * @since 1.8
+     */
+    public final Spliterator<E> spliterator() {
+        return new PriorityQueueSpliterator(0, -1, 0);
+    }
+
+    final class PriorityQueueSpliterator implements Spliterator<E> {
+        /*
+         * This is very similar to ArrayList Spliterator, except for
+         * extra null checks.
+         */
+        private int index;            // current index, modified on advance/split
+        private int fence;            // -1 until first use
+        private int expectedModCount; // initialized when fence set
+
+        /** Creates new spliterator covering the given range. */
+        PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
+            this.index = origin;
+            this.fence = fence;
+            this.expectedModCount = expectedModCount;
+        }
+
+        private int getFence() { // initialize fence to size on first use
+            int hi;
+            if ((hi = fence) < 0) {
+                expectedModCount = modCount;
+                hi = fence = size;
+            }
+            return hi;
+        }
+
+        public PriorityQueueSpliterator trySplit() {
+            int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
+            return (lo >= mid) ? null :
+                new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
+        }
+
+        @SuppressWarnings("unchecked")
+        public void forEachRemaining(Consumer<? super E> action) {
+            int i, hi, mc; // hoist accesses and checks from loop
+            final Object[] a;
+            if (action == null)
+                throw new NullPointerException();
+            if ((a = queue) != null) {
+                if ((hi = fence) < 0) {
+                    mc = modCount;
+                    hi = size;
+                }
+                else
+                    mc = expectedModCount;
+                if ((i = index) >= 0 && (index = hi) <= a.length) {
+                    for (E e;; ++i) {
+                        if (i < hi) {
+                            if ((e = (E) a[i]) == null) // must be CME
+                                break;
+                            action.accept(e);
+                        }
+                        else if (modCount != mc)
+                            break;
+                        else
+                            return;
+                    }
+                }
+            }
+            throw new ConcurrentModificationException();
+        }
+
+        public boolean tryAdvance(Consumer<? super E> action) {
+            if (action == null)
+                throw new NullPointerException();
+            int hi = getFence(), lo = index;
+            if (lo >= 0 && lo < hi) {
+                index = lo + 1;
+                @SuppressWarnings("unchecked") E e = (E)queue[lo];
+                if (e == null)
+                    throw new ConcurrentModificationException();
+                action.accept(e);
+                if (modCount != expectedModCount)
+                    throw new ConcurrentModificationException();
+                return true;
+            }
+            return false;
+        }
+
+        public long estimateSize() {
+            return getFence() - index;
+        }
+
+        public int characteristics() {
+            return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
+        }
+    }
 }