8016308: Updates to j.u.stream.Node/Nodes

Reviewed-by: mduigou
Contributed-by: NBrian Goetz &lt;brian.goetz@oracle.com&gt;, Paul Sandoz <paul.sandoz@oracle.com>

src/share/classes/java/util/stream/Node.java

@@ -104,6 +104,32 @@ interface Node<T> {
         throw new IndexOutOfBoundsException();
     }
 
+    /**
+     * Return a node describing a subsequence of the elements of this node,
+     * starting at the given inclusive start offset and ending at the given
+     * exclusive end offset.
+     *
+     * @param from The (inclusive) starting offset of elements to include, must
+     *             be in range 0..count().
+     * @param to The (exclusive) end offset of elements to include, must be
+     *           in range 0..count().
+     * @param generator A function to be used to create a new array, if needed,
+     *                  for reference nodes.
+     * @return the truncated node
+     */
+    default Node<T> truncate(long from, long to, IntFunction<T[]> generator) {
+        if (from == 0 && to == count())
+            return this;
+        Spliterator<T> spliterator = spliterator();
+        long size = to - from;
+        Node.Builder<T> nodeBuilder = Nodes.builder(size, generator);
+        nodeBuilder.begin(size);
+        for (int i = 0; i < from && spliterator.tryAdvance(e -> { }); i++) { }
+        for (int i = 0; (i < size) && spliterator.tryAdvance(nodeBuilder); i++) { }
+        nodeBuilder.end();
+        return nodeBuilder.build();
+    }
+
     /**
      * Provides an array view of the contents of this node.
      *
@@ -192,19 +218,90 @@ interface Node<T> {
         }
     }
 
-    /**
-     * Specialized {@code Node} for int elements
-     */
-    interface OfInt extends Node<Integer> {
+    public interface OfPrimitive<T, T_CONS, T_ARR,
+                                 T_SPLITR extends Spliterator.OfPrimitive<T, T_CONS, T_SPLITR>,
+                                 T_NODE extends OfPrimitive<T, T_CONS, T_ARR, T_SPLITR, T_NODE>>
+            extends Node<T> {
 
         /**
          * {@inheritDoc}
          *
-         * @return a {@link Spliterator.OfInt} describing the elements of this
-         *         node
+         * @return a {@link Spliterator.OfPrimitive} describing the elements of
+         *         this node
          */
         @Override
-        Spliterator.OfInt spliterator();
+        T_SPLITR spliterator();
+
+        /**
+         * Traverses the elements of this node, and invoke the provided
+         * {@code action} with each element.
+         *
+         * @param action a consumer that is to be invoked with each
+         *        element in this {@code Node.OfPrimitive}
+         */
+        void forEach(T_CONS action);
+
+        @Override
+        default T_NODE getChild(int i) {
+            throw new IndexOutOfBoundsException();
+        }
+
+        T_NODE truncate(long from, long to, IntFunction<T[]> generator);
+
+        /**
+         * {@inheritDoc}
+         *
+         * @implSpec the default implementation invokes the generator to create
+         * an instance of a boxed primitive array with a length of
+         * {@link #count()} and then invokes {@link #copyInto(T[], int)} with
+         * that array at an offset of 0.
+         */
+        @Override
+        default T[] asArray(IntFunction<T[]> generator) {
+            T[] boxed = generator.apply((int) count());
+            copyInto(boxed, 0);
+            return boxed;
+        }
+
+        /**
+         * Views this node as a primitive array.
+         *
+         * <p>Depending on the underlying implementation this may return a
+         * reference to an internal array rather than a copy.  It is the callers
+         * responsibility to decide if either this node or the array is utilized
+         * as the primary reference for the data.</p>
+         *
+         * @return an array containing the contents of this {@code Node}
+         */
+        T_ARR asPrimitiveArray();
+
+        /**
+         * Creates a new primitive array.
+         *
+         * @param count the length of the primitive array.
+         * @return the new primitive array.
+         */
+        T_ARR newArray(int count);
+
+        /**
+         * Copies the content of this {@code Node} into a primitive array,
+         * starting at a given offset into the array.  It is the caller's
+         * responsibility to ensure there is sufficient room in the array.
+         *
+         * @param array the array into which to copy the contents of this
+         *              {@code Node}
+         * @param offset the starting offset within the array
+         * @throws IndexOutOfBoundsException if copying would cause access of
+         *         data outside array bounds
+         * @throws NullPointerException if {@code array} is {@code null}
+         */
+        void copyInto(T_ARR array, int offset);
+    }
+
+    /**
+     * Specialized {@code Node} for int elements
+     */
+    interface OfInt extends OfPrimitive<Integer, IntConsumer, int[], Spliterator.OfInt, OfInt> {
 
         /**
          * {@inheritDoc}
@@ -226,38 +323,13 @@ interface Node<T> {
             }
         }
 
-        /**
-         * Traverses the elements of this node, and invoke the provided
-         * {@code IntConsumer} with each element.
-         *
-         * @param consumer a {@code IntConsumer} that is to be invoked with each
-         *        element in this {@code Node}
-         */
-        void forEach(IntConsumer consumer);
-
-        /**
-         * {@inheritDoc}
-         *
-         * @implSpec the default implementation invokes the generator to create
-         * an instance of an Integer[] array with a length of {@link #count()}
-         * and then invokes {@link #copyInto(Integer[], int)} with that
-         * Integer[] array at an offset of 0.  This is not efficient and it is
-         * recommended to invoke {@link #asPrimitiveArray()}.
-         */
-        @Override
-        default Integer[] asArray(IntFunction<Integer[]> generator) {
-            Integer[] boxed = generator.apply((int) count());
-            copyInto(boxed, 0);
-            return boxed;
-        }
-
         /**
          * {@inheritDoc}
          *
          * @implSpec the default implementation invokes {@link #asPrimitiveArray()} to
          * obtain an int[] array then and copies the elements from that int[]
          * array into the boxed Integer[] array.  This is not efficient and it
-         * is recommended to invoke {@link #copyInto(int[], int)}.
+         * is recommended to invoke {@link #copyInto(Object, int)}.
          */
         @Override
         default void copyInto(Integer[] boxed, int offset) {
@@ -271,35 +343,23 @@ interface Node<T> {
         }
 
         @Override
-        default Node.OfInt getChild(int i) {
-            throw new IndexOutOfBoundsException();
+        default Node.OfInt truncate(long from, long to, IntFunction<Integer[]> generator) {
+            if (from == 0 && to == count())
+                return this;
+            long size = to - from;
+            Spliterator.OfInt spliterator = spliterator();
+            Node.Builder.OfInt nodeBuilder = Nodes.intBuilder(size);
+            nodeBuilder.begin(size);
+            for (int i = 0; i < from && spliterator.tryAdvance((IntConsumer) e -> { }); i++) { }
+            for (int i = 0; (i < size) && spliterator.tryAdvance((IntConsumer) nodeBuilder); i++) { }
+            nodeBuilder.end();
+            return nodeBuilder.build();
         }
 
-        /**
-         * Views this node as an int[] array.
-         *
-         * <p>Depending on the underlying implementation this may return a
-         * reference to an internal array rather than a copy.  It is the callers
-         * responsibility to decide if either this node or the array is utilized
-         * as the primary reference for the data.</p>
-         *
-         * @return an array containing the contents of this {@code Node}
-         */
-        int[] asPrimitiveArray();
-
-        /**
-         * Copies the content of this {@code Node} into an int[] array, starting
-         * at a given offset into the array.  It is the caller's responsibility
-         * to ensure there is sufficient room in the array.
-         *
-         * @param array the array into which to copy the contents of this
-         *              {@code Node}
-         * @param offset the starting offset within the array
-         * @throws IndexOutOfBoundsException if copying would cause access of
-         *         data outside array bounds
-         * @throws NullPointerException if {@code array} is {@code null}
-         */
-        void copyInto(int[] array, int offset);
+        @Override
+        default int[] newArray(int count) {
+            return new int[count];
+        }
 
         /**
          * {@inheritDoc}
@@ -309,22 +369,12 @@ interface Node<T> {
         default StreamShape getShape() {
             return StreamShape.INT_VALUE;
         }
-
     }
 
     /**
      * Specialized {@code Node} for long elements
      */
-    interface OfLong extends Node<Long> {
-
-        /**
-         * {@inheritDoc}
-         *
-         * @return a {@link Spliterator.OfLong} describing the elements of this
-         *         node
-         */
-        @Override
-        Spliterator.OfLong spliterator();
+    interface OfLong extends OfPrimitive<Long, LongConsumer, long[], Spliterator.OfLong, OfLong> {
 
         /**
          * {@inheritDoc}
@@ -346,38 +396,13 @@ interface Node<T> {
             }
         }
 
-        /**
-         * Traverses the elements of this node, and invoke the provided
-         * {@code LongConsumer} with each element.
-         *
-         * @param consumer a {@code LongConsumer} that is to be invoked with
-         *        each element in this {@code Node}
-         */
-        void forEach(LongConsumer consumer);
-
-        /**
-         * {@inheritDoc}
-         *
-         * @implSpec the default implementation invokes the generator to create
-         * an instance of a Long[] array with a length of {@link #count()} and
-         * then invokes {@link #copyInto(Long[], int)} with that Long[] array at
-         * an offset of 0.  This is not efficient and it is recommended to
-         * invoke {@link #asPrimitiveArray()}.
-         */
-        @Override
-        default Long[] asArray(IntFunction<Long[]> generator) {
-            Long[] boxed = generator.apply((int) count());
-            copyInto(boxed, 0);
-            return boxed;
-        }
-
         /**
          * {@inheritDoc}
          *
          * @implSpec the default implementation invokes {@link #asPrimitiveArray()}
          * to obtain a long[] array then and copies the elements from that
          * long[] array into the boxed Long[] array.  This is not efficient and
-         * it is recommended to invoke {@link #copyInto(long[], int)}.
+         * it is recommended to invoke {@link #copyInto(Object, int)}.
          */
         @Override
         default void copyInto(Long[] boxed, int offset) {
@@ -391,35 +416,23 @@ interface Node<T> {
         }
 
         @Override
-        default Node.OfLong getChild(int i) {
-            throw new IndexOutOfBoundsException();
+        default Node.OfLong truncate(long from, long to, IntFunction<Long[]> generator) {
+            if (from == 0 && to == count())
+                return this;
+            long size = to - from;
+            Spliterator.OfLong spliterator = spliterator();
+            Node.Builder.OfLong nodeBuilder = Nodes.longBuilder(size);
+            nodeBuilder.begin(size);
+            for (int i = 0; i < from && spliterator.tryAdvance((LongConsumer) e -> { }); i++) { }
+            for (int i = 0; (i < size) && spliterator.tryAdvance((LongConsumer) nodeBuilder); i++) { }
+            nodeBuilder.end();
+            return nodeBuilder.build();
         }
 
-        /**
-         * Views this node as a long[] array.
-         *
-         * <p/>Depending on the underlying implementation this may return a
-         * reference to an internal array rather than a copy. It is the callers
-         * responsibility to decide if either this node or the array is utilized
-         * as the primary reference for the data.
-         *
-         * @return an array containing the contents of this {@code Node}
-         */
-        long[] asPrimitiveArray();
-
-        /**
-         * Copies the content of this {@code Node} into a long[] array, starting
-         * at a given offset into the array.  It is the caller's responsibility
-         * to ensure there is sufficient room in the array.
-         *
-         * @param array the array into which to copy the contents of this
-         *        {@code Node}
-         * @param offset the starting offset within the array
-         * @throws IndexOutOfBoundsException if copying would cause access of
-         *         data outside array bounds
-         * @throws NullPointerException if {@code array} is {@code null}
-         */
-        void copyInto(long[] array, int offset);
+        @Override
+        default long[] newArray(int count) {
+            return new long[count];
+        }
 
         /**
          * {@inheritDoc}
@@ -429,23 +442,12 @@ interface Node<T> {
         default StreamShape getShape() {
             return StreamShape.LONG_VALUE;
         }
-
-
     }
 
     /**
      * Specialized {@code Node} for double elements
      */
-    interface OfDouble extends Node<Double> {
-
-        /**
-         * {@inheritDoc}
-         *
-         * @return A {@link Spliterator.OfDouble} describing the elements of
-         *         this node
-         */
-        @Override
-        Spliterator.OfDouble spliterator();
+    interface OfDouble extends OfPrimitive<Double, DoubleConsumer, double[], Spliterator.OfDouble, OfDouble> {
 
         /**
          * {@inheritDoc}
@@ -467,40 +469,15 @@ interface Node<T> {
             }
         }
 
-        /**
-         * Traverses the elements of this node, and invoke the provided
-         * {@code DoubleConsumer} with each element.
-         *
-         * @param consumer A {@code DoubleConsumer} that is to be invoked with
-         *        each element in this {@code Node}
-         */
-        void forEach(DoubleConsumer consumer);
-
         //
 
-        /**
-         * {@inheritDoc}
-         *
-         * @implSpec the default implementation invokes the generator to create
-         * an instance of a Double[] array with a length of {@link #count()} and
-         * then invokes {@link #copyInto(Double[], int)} with that Double[]
-         * array at an offset of 0.  This is not efficient and it is recommended
-         * to invoke {@link #asPrimitiveArray()}.
-         */
-        @Override
-        default Double[] asArray(IntFunction<Double[]> generator) {
-            Double[] boxed = generator.apply((int) count());
-            copyInto(boxed, 0);
-            return boxed;
-        }
-
         /**
          * {@inheritDoc}
          *
          * @implSpec the default implementation invokes {@link #asPrimitiveArray()}
          * to obtain a double[] array then and copies the elements from that
          * double[] array into the boxed Double[] array.  This is not efficient
-         * and it is recommended to invoke {@link #copyInto(double[], int)}.
+         * and it is recommended to invoke {@link #copyInto(Object, int)}.
          */
         @Override
         default void copyInto(Double[] boxed, int offset) {
@@ -514,35 +491,23 @@ interface Node<T> {
         }
 
         @Override
-        default Node.OfDouble getChild(int i) {
-            throw new IndexOutOfBoundsException();
+        default Node.OfDouble truncate(long from, long to, IntFunction<Double[]> generator) {
+            if (from == 0 && to == count())
+                return this;
+            long size = to - from;
+            Spliterator.OfDouble spliterator = spliterator();
+            Node.Builder.OfDouble nodeBuilder = Nodes.doubleBuilder(size);
+            nodeBuilder.begin(size);
+            for (int i = 0; i < from && spliterator.tryAdvance((DoubleConsumer) e -> { }); i++) { }
+            for (int i = 0; (i < size) && spliterator.tryAdvance((DoubleConsumer) nodeBuilder); i++) { }
+            nodeBuilder.end();
+            return nodeBuilder.build();
         }
 
-        /**
-         * Views this node as a double[] array.
-         *
-         * <p/>Depending on the underlying implementation this may return a
-         * reference to an internal array rather than a copy.  It is the callers
-         * responsibility to decide if either this node or the array is utilized
-         * as the primary reference for the data.
-         *
-         * @return an array containing the contents of this {@code Node}
-         */
-        double[] asPrimitiveArray();
-
-        /**
-         * Copies the content of this {@code Node} into a double[] array, starting
-         * at a given offset into the array.  It is the caller's responsibility
-         * to ensure there is sufficient room in the array.
-         *
-         * @param array the array into which to copy the contents of this
-         *        {@code Node}
-         * @param offset the starting offset within the array
-         * @throws IndexOutOfBoundsException if copying would cause access of
-         *         data outside array bounds
-         * @throws NullPointerException if {@code array} is {@code null}
-         */
-        void copyInto(double[] array, int offset);
+        @Override
+        default double[] newArray(int count) {
+            return new double[count];
+        }
 
         /**
          * {@inheritDoc}

src/share/classes/java/util/stream/SliceOps.java

@@ -28,7 +28,10 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Spliterator;
 import java.util.concurrent.CountedCompleter;
+import java.util.function.DoubleConsumer;
+import java.util.function.IntConsumer;
 import java.util.function.IntFunction;
+import java.util.function.LongConsumer;
 
 /**
  * Factory for instances of a short-circuiting stateful intermediate operations
@@ -352,7 +355,7 @@ final class SliceOps {
                     else
                         // This will create a tree of depth 1 and will not be a sub-tree
                         // for leaf nodes within the require range
-                        result = Nodes.conc(op.getOutputShape(), nodes);
+                        result = conc(op.getOutputShape(), nodes);
                     setLocalResult(result);
                 }
             }
@@ -418,94 +421,116 @@ final class SliceOps {
             if (skipLeft == 0 && skipRight == 0)
                 return input;
             else {
-                return Nodes.truncateNode(input, skipLeft, thisNodeSize - skipRight, generator);
+                return truncateNode(input, skipLeft, thisNodeSize - skipRight, generator);
+            }
+        }
+        /**
+         * Truncate a {@link Node}, returning a node describing a subsequence of
+         * the contents of the input node.
+         *
+         * @param <T> the type of elements of the input node and truncated node
+         * @param input the input node
+         * @param from the starting offset to include in the truncated node (inclusive)
+         * @param to the ending offset ot include in the truncated node (exclusive)
+         * @param generator the array factory (only used for reference nodes)
+         * @return the truncated node
+         */
+        @SuppressWarnings("unchecked")
+        private static <T> Node<T> truncateNode(Node<T> input, long from, long to, IntFunction<T[]> generator) {
+            StreamShape shape = input.getShape();
+            long size = truncatedSize(input.count(), from, to);
+            if (size == 0)
+                return Nodes.emptyNode(shape);
+            else if (from == 0 && to >= input.count())
+                return input;
+
+            switch (shape) {
+                case REFERENCE: {
+                    Spliterator<T> spliterator = input.spliterator();
+                    Node.Builder<T> nodeBuilder = Nodes.builder(size, generator);
+                    nodeBuilder.begin(size);
+                    for (int i = 0; i < from && spliterator.tryAdvance(e -> { }); i++) { }
+                    for (int i = 0; (i < size) && spliterator.tryAdvance(nodeBuilder); i++) { }
+                    nodeBuilder.end();
+                    return nodeBuilder.build();
+                }
+                case INT_VALUE: {
+                    Spliterator.OfInt spliterator = ((Node.OfInt) input).spliterator();
+                    Node.Builder.OfInt nodeBuilder = Nodes.intBuilder(size);
+                    nodeBuilder.begin(size);
+                    for (int i = 0; i < from && spliterator.tryAdvance((IntConsumer) e -> { }); i++) { }
+                    for (int i = 0; (i < size) && spliterator.tryAdvance((IntConsumer) nodeBuilder); i++) { }
+                    nodeBuilder.end();
+                    return (Node<T>) nodeBuilder.build();
+                }
+                case LONG_VALUE: {
+                    Spliterator.OfLong spliterator = ((Node.OfLong) input).spliterator();
+                    Node.Builder.OfLong nodeBuilder = Nodes.longBuilder(size);
+                    nodeBuilder.begin(size);
+                    for (int i = 0; i < from && spliterator.tryAdvance((LongConsumer) e -> { }); i++) { }
+                    for (int i = 0; (i < size) && spliterator.tryAdvance((LongConsumer) nodeBuilder); i++) { }
+                    nodeBuilder.end();
+                    return (Node<T>) nodeBuilder.build();
+                }
+                case DOUBLE_VALUE: {
+                    Spliterator.OfDouble spliterator = ((Node.OfDouble) input).spliterator();
+                    Node.Builder.OfDouble nodeBuilder = Nodes.doubleBuilder(size);
+                    nodeBuilder.begin(size);
+                    for (int i = 0; i < from && spliterator.tryAdvance((DoubleConsumer) e -> { }); i++) { }
+                    for (int i = 0; (i < size) && spliterator.tryAdvance((DoubleConsumer) nodeBuilder); i++) { }
+                    nodeBuilder.end();
+                    return (Node<T>) nodeBuilder.build();
+                }
+                default:
+                    throw new IllegalStateException("Unknown shape " + shape);
             }
         }
-    }
 
-    // @@@ Currently unused -- optimization for when all sizes are known
-//    private static class SizedSliceTask<S, T> extends AbstractShortCircuitTask<S, T, Node<T>, SizedSliceTask<S, T>> {
-//        private final int targetOffset, targetSize;
-//        private final int offset, size;
-//
-//        private SizedSliceTask(ParallelPipelineHelper<S, T> helper, int offset, int size) {
-//            super(helper);
-//            targetOffset = offset;
-//            targetSize = size;
-//            this.offset = 0;
-//            this.size = spliterator.getSizeIfKnown();
-//        }
-//
-//        private SizedSliceTask(SizedSliceTask<S, T> parent, Spliterator<S> spliterator) {
-//            // Makes assumptions about order in which siblings are created and linked into parent!
-//            super(parent, spliterator);
-//            targetOffset = parent.targetOffset;
-//            targetSize = parent.targetSize;
-//            int siblingSizes = 0;
-//            for (SizedSliceTask<S, T> sibling = parent.children; sibling != null; sibling = sibling.nextSibling)
-//                siblingSizes += sibling.size;
-//            size = spliterator.getSizeIfKnown();
-//            offset = parent.offset + siblingSizes;
-//        }
-//
-//        @Override
-//        protected SizedSliceTask<S, T> makeChild(Spliterator<S> spliterator) {
-//            return new SizedSliceTask<>(this, spliterator);
-//        }
-//
-//        @Override
-//        protected Node<T> getEmptyResult() {
-//            return Nodes.emptyNode();
-//        }
-//
-//        @Override
-//        public boolean taskCanceled() {
-//            if (offset > targetOffset+targetSize || offset+size < targetOffset)
-//                return true;
-//            else
-//                return super.taskCanceled();
-//        }
-//
-//        @Override
-//        protected Node<T> doLeaf() {
-//            int skipLeft = Math.max(0, targetOffset - offset);
-//            int skipRight = Math.max(0, offset + size - (targetOffset + targetSize));
-//            if (skipLeft == 0 && skipRight == 0)
-//                return helper.into(Nodes.<T>makeBuilder(spliterator.getSizeIfKnown())).build();
-//            else {
-//                // If we're the first or last node that intersects the target range, peel off irrelevant elements
-//                int truncatedSize = size - skipLeft - skipRight;
-//                NodeBuilder<T> builder = Nodes.<T>makeBuilder(truncatedSize);
-//                Sink<S> wrappedSink = helper.wrapSink(builder);
-//                wrappedSink.begin(truncatedSize);
-//                Iterator<S> iterator = spliterator.iterator();
-//                for (int i=0; i<skipLeft; i++)
-//                    iterator.next();
-//                for (int i=0; i<truncatedSize; i++)
-//                    wrappedSink.apply(iterator.next());
-//                wrappedSink.end();
-//                return builder.build();
-//            }
-//        }
-//
-//        @Override
-//        public void onCompletion(CountedCompleter<?> caller) {
-//            if (!isLeaf()) {
-//                Node<T> result = null;
-//                for (SizedSliceTask<S, T> child = children.nextSibling; child != null; child = child.nextSibling) {
-//                    Node<T> childResult = child.getRawResult();
-//                    if (childResult == null)
-//                        continue;
-//                    else if (result == null)
-//                        result = childResult;
-//                    else
-//                        result = Nodes.node(result, childResult);
-//                }
-//                setRawResult(result);
-//                if (offset <= targetOffset && offset+size >= targetOffset+targetSize)
-//                    shortCircuit(result);
-//            }
-//        }
-//    }
+        private static long truncatedSize(long size, long from, long to) {
+            if (from >= 0)
+                size = Math.max(0, size - from);
+            long limit = to - from;
+            if (limit >= 0)
+                size = Math.min(size, limit);
+            return size;
+        }
+
+        /**
+         * Produces a concatenated {@link Node} that has two or more children.
+         * <p>The count of the concatenated node is equal to the sum of the count
+         * of each child. Traversal of the concatenated node traverses the content
+         * of each child in encounter order of the list of children. Splitting a
+         * spliterator obtained from the concatenated node preserves the encounter
+         * order of the list of children.
+         *
+         * <p>The result may be a concatenated node, the input sole node if the size
+         * of the list is 1, or an empty node.
+         *
+         * @param <T> the type of elements of the concatenated node
+         * @param shape the shape of the concatenated node to be created
+         * @param nodes the input nodes
+         * @return a {@code Node} covering the elements of the input nodes
+         * @throws IllegalStateException if all {@link Node} elements of the list
+         * are an not instance of type supported by this factory.
+         */
+        @SuppressWarnings("unchecked")
+        private static <T> Node<T> conc(StreamShape shape, List<? extends Node<T>> nodes) {
+            int size = nodes.size();
+            if (size == 0)
+                return Nodes.emptyNode(shape);
+            else if (size == 1)
+                return nodes.get(0);
+            else {
+                // Create a right-balanced tree when there are more that 2 nodes
+                List<Node<T>> refNodes = (List<Node<T>>) nodes;
+                Node<T> c = Nodes.conc(shape, refNodes.get(size - 2), refNodes.get(size - 1));
+                for (int i = size - 3; i >= 0; i--) {
+                    c = Nodes.conc(shape, refNodes.get(i), c);
+                }
+                return c;
+            }
+        }
+
+    }
 
 }

test/java/util/stream/boottest/java/util/stream/DoubleNodeTest.java

@@ -102,7 +102,7 @@ public class DoubleNodeTest extends OpTestCase {
 
         double i = it.nextDouble();
         if (it.hasNext()) {
-            return new Nodes.DoubleConcNode(Nodes.node(new double[] {i}), degenerateTree(it));
+            return new Nodes.ConcNode.OfDouble(Nodes.node(new double[] {i}), degenerateTree(it));
         }
         else {
             return Nodes.node(new double[] {i});
@@ -114,7 +114,7 @@ public class DoubleNodeTest extends OpTestCase {
             return m.apply(l);
         }
         else {
-            return new Nodes.DoubleConcNode(
+            return new Nodes.ConcNode.OfDouble(
                     tree(l.subList(0, l.size() / 2), m),
                     tree(l.subList(l.size() / 2, l.size()), m));
         }

test/java/util/stream/boottest/java/util/stream/IntNodeTest.java

@@ -102,7 +102,7 @@ public class IntNodeTest extends OpTestCase {
 
         int i = it.nextInt();
         if (it.hasNext()) {
-            return new Nodes.IntConcNode(Nodes.node(new int[] {i}), degenerateTree(it));
+            return new Nodes.ConcNode.OfInt(Nodes.node(new int[] {i}), degenerateTree(it));
         }
         else {
             return Nodes.node(new int[] {i});
@@ -114,7 +114,7 @@ public class IntNodeTest extends OpTestCase {
             return m.apply(l);
         }
         else {
-            return new Nodes.IntConcNode(
+            return new Nodes.ConcNode.OfInt(
                     tree(l.subList(0, l.size() / 2), m),
                     tree(l.subList(l.size() / 2, l.size()), m));
         }

test/java/util/stream/boottest/java/util/stream/LongNodeTest.java

@@ -102,7 +102,7 @@ public class LongNodeTest extends OpTestCase {
 
         long i = it.nextLong();
         if (it.hasNext()) {
-            return new Nodes.LongConcNode(Nodes.node(new long[] {i}), degenerateTree(it));
+            return new Nodes.ConcNode.OfLong(Nodes.node(new long[] {i}), degenerateTree(it));
         }
         else {
             return Nodes.node(new long[] {i});
@@ -114,7 +114,7 @@ public class LongNodeTest extends OpTestCase {
             return m.apply(l);
         }
         else {
-            return new Nodes.LongConcNode(
+            return new Nodes.ConcNode.OfLong(
                     tree(l.subList(0, l.size() / 2), m),
                     tree(l.subList(l.size() / 2, l.size()), m));
         }