--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/util/stream/AbstractSpinedBuffer.java	Wed Apr 24 16:15:47 2013 -0700
@@ -0,0 +1,127 @@
+/*
+ * Copyright (c) 2012, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * 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
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package java.util.stream;
+
+/**
+ * Base class for a data structure for gathering elements into a buffer and then
+ * iterating them. Maintains an array of increasingly sized arrays, so there is
+ * no copying cost associated with growing the data structure.
+ * @since 1.8
+ */
+abstract class AbstractSpinedBuffer {
+    /**
+     * Minimum power-of-two for the first chunk.
+     */
+    public static final int MIN_CHUNK_POWER = 4;
+
+    /**
+     * Minimum size for the first chunk.
+     */
+    public static final int MIN_CHUNK_SIZE = 1 << MIN_CHUNK_POWER;
+
+    /**
+     * Max power-of-two for chunks.
+     */
+    public static final int MAX_CHUNK_POWER = 30;
+
+    /**
+     * Minimum array size for array-of-chunks.
+     */
+    public static final int MIN_SPINE_SIZE = 8;
+
+
+    /**
+     * log2 of the size of the first chunk.
+     */
+    protected final int initialChunkPower;
+
+    /**
+     * Index of the *next* element to write; may point into, or just outside of,
+     * the current chunk.
+     */
+    protected int elementIndex;
+
+    /**
+     * Index of the *current* chunk in the spine array, if the spine array is
+     * non-null.
+     */
+    protected int spineIndex;
+
+    /**
+     * Count of elements in all prior chunks.
+     */
+    protected long[] priorElementCount;
+
+    /**
+     * Construct with an initial capacity of 16.
+     */
+    protected AbstractSpinedBuffer() {
+        this.initialChunkPower = MIN_CHUNK_POWER;
+    }
+
+    /**
+     * Construct with a specified initial capacity.
+     *
+     * @param initialCapacity The minimum expected number of elements
+     */
+    protected AbstractSpinedBuffer(int initialCapacity) {
+        if (initialCapacity < 0)
+            throw new IllegalArgumentException("Illegal Capacity: "+ initialCapacity);
+
+        this.initialChunkPower = Math.max(MIN_CHUNK_POWER,
+                                          Integer.SIZE - Integer.numberOfLeadingZeros(initialCapacity - 1));
+    }
+
+    /**
+     * Is the buffer currently empty?
+     */
+    public boolean isEmpty() {
+        return (spineIndex == 0) && (elementIndex == 0);
+    }
+
+    /**
+     * How many elements are currently in the buffer?
+     */
+    public long count() {
+        return (spineIndex == 0)
+               ? elementIndex
+               : priorElementCount[spineIndex] + elementIndex;
+    }
+
+    /**
+     * How big should the nth chunk be?
+     */
+    protected int chunkSize(int n) {
+        int power = (n == 0 || n == 1)
+                    ? initialChunkPower
+                    : Math.min(initialChunkPower + n - 1, AbstractSpinedBuffer.MAX_CHUNK_POWER);
+        return 1 << power;
+    }
+
+    /**
+     * Remove all data from the buffer
+     */
+    public abstract void clear();
+}