--- jsr166/src/main/java/util/ArrayDeque.java 2016/11/18 03:48:28 1.115
+++ jsr166/src/main/java/util/ArrayDeque.java 2018/10/01 00:10:52 1.135
@@ -9,6 +9,7 @@ import java.io.Serializable;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.function.UnaryOperator;
+import jdk.internal.misc.SharedSecrets;
/**
* Resizable-array implementation of the {@link Deque} interface. Array
@@ -50,7 +51,7 @@ import java.util.function.UnaryOperator;
* Iterator} interfaces.
*
*
This class is a member of the
- *
+ *
* Java Collections Framework.
*
* @author Josh Bloch and Doug Lea
@@ -117,16 +118,16 @@ public class ArrayDeque extends Abstr
if (jump < needed
|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0)
newCapacity = newCapacity(needed, jump);
- elements = Arrays.copyOf(elements, newCapacity);
+ final Object[] es = elements = Arrays.copyOf(elements, newCapacity);
// Exceptionally, here tail == head needs to be disambiguated
- if (tail < head || (tail == head && elements[head] != null)) {
+ if (tail < head || (tail == head && es[head] != null)) {
// wrap around; slide first leg forward to end of array
int newSpace = newCapacity - oldCapacity;
- System.arraycopy(elements, head,
- elements, head + newSpace,
+ System.arraycopy(es, head,
+ es, head + newSpace,
oldCapacity - head);
- Arrays.fill(elements, head, head + newSpace, null);
- head += newSpace;
+ for (int i = head, to = (head += newSpace); i < to; i++)
+ es[i] = null;
}
// checkInvariants();
}
@@ -180,7 +181,7 @@ public class ArrayDeque extends Abstr
* sufficient to hold 16 elements.
*/
public ArrayDeque() {
- elements = new Object[16];
+ elements = new Object[16 + 1];
}
/**
@@ -208,11 +209,11 @@ public class ArrayDeque extends Abstr
*/
public ArrayDeque(Collection extends E> c) {
this(c.size());
- addAll(c);
+ copyElements(c);
}
/**
- * Increments i, mod modulus.
+ * Circularly increments i, mod modulus.
* Precondition and postcondition: 0 <= i < modulus.
*/
static final int inc(int i, int modulus) {
@@ -221,7 +222,7 @@ public class ArrayDeque extends Abstr
}
/**
- * Decrements i, mod modulus.
+ * Circularly decrements i, mod modulus.
* Precondition and postcondition: 0 <= i < modulus.
*/
static final int dec(int i, int modulus) {
@@ -234,8 +235,8 @@ public class ArrayDeque extends Abstr
* Precondition: 0 <= i < modulus, 0 <= distance <= modulus.
* @return index 0 <= i < modulus
*/
- static final int add(int i, int distance, int modulus) {
- if ((i += distance) - modulus >= 0) distance -= modulus;
+ static final int inc(int i, int distance, int modulus) {
+ if ((i += distance) - modulus >= 0) i -= modulus;
return i;
}
@@ -244,7 +245,7 @@ public class ArrayDeque extends Abstr
* Index i must be logically ahead of index j.
* Precondition: 0 <= i < modulus, 0 <= j < modulus.
* @return the "circular distance" from j to i; corner case i == j
- * is diambiguated to "empty", returning 0.
+ * is disambiguated to "empty", returning 0.
*/
static final int sub(int i, int j, int modulus) {
if ((i -= j) < 0) i += modulus;
@@ -313,8 +314,7 @@ public class ArrayDeque extends Abstr
/**
* Adds all of the elements in the specified collection at the end
* of this deque, as if by calling {@link #addLast} on each one,
- * in the order that they are returned by the collection's
- * iterator.
+ * in the order that they are returned by the collection's iterator.
*
* @param c the elements to be inserted into this deque
* @return {@code true} if this deque changed as a result of the call
@@ -322,14 +322,18 @@ public class ArrayDeque extends Abstr
* of its elements are null
*/
public boolean addAll(Collection extends E> c) {
- final int s = size(), needed;
- if ((needed = s + c.size() - elements.length + 1) > 0)
+ final int s, needed;
+ if ((needed = (s = size()) + c.size() + 1 - elements.length) > 0)
grow(needed);
- c.forEach(e -> addLast(e));
+ copyElements(c);
// checkInvariants();
return size() > s;
}
+ private void copyElements(Collection extends E> c) {
+ c.forEach(this::addLast);
+ }
+
/**
* Inserts the specified element at the front of this deque.
*
@@ -520,8 +524,8 @@ public class ArrayDeque extends Abstr
/**
* Retrieves and removes the head of the queue represented by this deque.
*
- * This method differs from {@link #poll poll} only in that it throws an
- * exception if this deque is empty.
+ * This method differs from {@link #poll() poll()} only in that it
+ * throws an exception if this deque is empty.
*
* This method is equivalent to {@link #removeFirst}.
*
@@ -616,10 +620,11 @@ public class ArrayDeque extends Abstr
// checkInvariants();
final Object[] es = elements;
final int capacity = es.length;
- final int h = head;
+ final int h, t;
// number of elements before to-be-deleted elt
- final int front = sub(i, h, capacity);
- final int back = size() - front - 1; // number of elements after
+ final int front = sub(i, h = head, capacity);
+ // number of elements after to-be-deleted elt
+ final int back = sub(t = tail, i, capacity) - 1;
if (front < back) {
// move front elements forwards
if (h <= i) {
@@ -635,14 +640,13 @@ public class ArrayDeque extends Abstr
return false;
} else {
// move back elements backwards
- tail = dec(tail, capacity);
+ tail = dec(t, capacity);
if (i <= tail) {
System.arraycopy(es, i + 1, es, i, back);
} else { // Wrap around
- int firstLeg = capacity - (i + 1);
- System.arraycopy(es, i + 1, es, i, firstLeg);
+ System.arraycopy(es, i + 1, es, i, capacity - (i + 1));
es[capacity - 1] = es[0];
- System.arraycopy(es, 1, es, 0, back - firstLeg - 1);
+ System.arraycopy(es, 1, es, 0, t - 1);
}
es[tail] = null;
// checkInvariants();
@@ -710,8 +714,7 @@ public class ArrayDeque extends Abstr
throw new NoSuchElementException();
final Object[] es = elements;
E e = nonNullElementAt(es, cursor);
- lastRet = cursor;
- cursor = inc(cursor, es.length);
+ cursor = inc(lastRet = cursor, es.length);
remaining--;
return e;
}
@@ -759,8 +762,7 @@ public class ArrayDeque extends Abstr
throw new NoSuchElementException();
final Object[] es = elements;
E e = nonNullElementAt(es, cursor);
- lastRet = cursor;
- cursor = dec(cursor, es.length);
+ cursor = dec(lastRet = cursor, es.length);
remaining--;
return e;
}
@@ -822,6 +824,8 @@ public class ArrayDeque extends Abstr
/** Constructs spliterator over the given range. */
DeqSpliterator(int origin, int fence) {
+ // assert 0 <= origin && origin < elements.length;
+ // assert 0 <= fence && fence < elements.length;
this.cursor = origin;
this.fence = fence;
}
@@ -841,7 +845,7 @@ public class ArrayDeque extends Abstr
final int i, n;
return ((n = sub(getFence(), i = cursor, es.length) >> 1) <= 0)
? null
- : new DeqSpliterator(i, cursor = add(i, n, es.length));
+ : new DeqSpliterator(i, cursor = inc(i, n, es.length));
}
public void forEachRemaining(Consumer super E> action) {
@@ -864,14 +868,15 @@ public class ArrayDeque extends Abstr
}
public boolean tryAdvance(Consumer super E> action) {
- if (action == null)
- throw new NullPointerException();
- final int t, i;
- if ((t = getFence()) == (i = cursor))
- return false;
+ Objects.requireNonNull(action);
final Object[] es = elements;
+ if (fence < 0) { fence = tail; cursor = head; } // late-binding
+ final int i;
+ if ((i = cursor) == fence)
+ return false;
+ E e = nonNullElementAt(es, i);
cursor = inc(i, es.length);
- action.accept(nonNullElementAt(es, i));
+ action.accept(e);
return true;
}
@@ -887,6 +892,9 @@ public class ArrayDeque extends Abstr
}
}
+ /**
+ * @throws NullPointerException {@inheritDoc}
+ */
public void forEach(Consumer super E> action) {
Objects.requireNonNull(action);
final Object[] es = elements;
@@ -1075,11 +1083,14 @@ public class ArrayDeque extends Abstr
/**
* Nulls out slots starting at array index i, upto index end.
+ * Condition i == end means "empty" - nothing to do.
*/
private static void circularClear(Object[] es, int i, int end) {
+ // assert 0 <= i && i < es.length;
+ // assert 0 <= end && end < es.length;
for (int to = (i <= end) ? end : es.length;
; i = 0, to = end) {
- Arrays.fill(es, i, to, null);
+ for (; i < to; i++) es[i] = null;
if (to == end) break;
}
}
@@ -1104,17 +1115,17 @@ public class ArrayDeque extends Abstr
private T[] toArray(Class klazz) {
final Object[] es = elements;
final T[] a;
- final int size = size(), head = this.head, end;
- final int len = Math.min(size, es.length - head);
- if ((end = head + size) >= 0) {
+ final int head = this.head, tail = this.tail, end;
+ if ((end = tail + ((head <= tail) ? 0 : es.length)) >= 0) {
+ // Uses null extension feature of copyOfRange
a = Arrays.copyOfRange(es, head, end, klazz);
} else {
// integer overflow!
- a = Arrays.copyOfRange(es, 0, size, klazz);
- System.arraycopy(es, head, a, 0, len);
+ a = Arrays.copyOfRange(es, 0, end - head, klazz);
+ System.arraycopy(es, head, a, 0, es.length - head);
}
- if (tail < head)
- System.arraycopy(es, 0, a, len, tail);
+ if (end != tail)
+ System.arraycopy(es, 0, a, es.length - head, tail);
return a;
}
@@ -1229,6 +1240,7 @@ public class ArrayDeque extends Abstr
// Read in size and allocate array
int size = s.readInt();
+ SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size + 1);
elements = new Object[size + 1];
this.tail = size;
@@ -1243,8 +1255,8 @@ public class ArrayDeque extends Abstr
// head == tail disambiguates to "empty".
try {
int capacity = elements.length;
- // assert head >= 0 && head < capacity;
- // assert tail >= 0 && tail < capacity;
+ // assert 0 <= head && head < capacity;
+ // assert 0 <= tail && tail < capacity;
// assert capacity > 0;
// assert size() < capacity;
// assert head == tail || elements[head] != null;