--- jsr166/src/main/java/util/ArrayDeque.java 2016/11/20 07:24:11 1.118 +++ jsr166/src/main/java/util/ArrayDeque.java 2017/05/31 19:01:08 1.129 @@ -50,7 +50,7 @@ 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 +117,16 @@ 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(); } @@ -235,7 +235,7 @@ public class ArrayDeque extends Abstr * @return index 0 <= i < modulus */ static final int add(int i, int distance, int modulus) { - if ((i += distance) - modulus >= 0) distance -= modulus; + if ((i += distance) - modulus >= 0) i -= modulus; return i; } @@ -313,8 +313,7 @@ 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 @@ -520,8 +519,8 @@ 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}. * @@ -710,8 +709,7 @@ 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 +757,7 @@ 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 +819,8 @@ 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; } @@ -864,14 +863,15 @@ public class ArrayDeque extends Abstr } public boolean tryAdvance(Consumer 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 +887,9 @@ public class ArrayDeque extends Abstr } } + /** + * @throws NullPointerException {@inheritDoc} + */ public void forEach(Consumer action) { Objects.requireNonNull(action); final Object[] es = elements; @@ -1075,11 +1078,14 @@ 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 +1110,17 @@ 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; } @@ -1243,8 +1249,8 @@ 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;