--- /dev/null	2015-04-26 06:51:08.003313989 -0700
+++ new/jdk/src/jdk.jline/share/classes/jdk/internal/jline/console/KillRing.java	2015-06-18 03:04:38.163616842 -0700
@@ -0,0 +1,164 @@
+/*
+ * Copyright (c) 2002-2013, the original author or authors.
+ *
+ * This software is distributable under the BSD license. See the terms of the
+ * BSD license in the documentation provided with this software.
+ *
+ * http://www.opensource.org/licenses/bsd-license.php
+ */
+package jdk.internal.jline.console;
+
+/**
+ * The kill ring class keeps killed text in a fixed size ring. In this
+ * class we also keep record of whether or not the last command was a
+ * kill or a yank. Depending on this, the class may behave
+ * different. For instance, two consecutive kill-word commands fill
+ * the same slot such that the next yank will return the two
+ * previously killed words instead that only the last one. Likewise
+ * yank pop requires that the previous command was either a yank or a
+ * yank-pop.
+ */
+public final class KillRing {
+
+    /**
+     * Default size is 60, like in emacs.
+     */
+    private static final int DEFAULT_SIZE = 60;
+
+    private final String[] slots;
+    private int head = 0;
+    private boolean lastKill = false;
+    private boolean lastYank = false;
+
+    /**
+     * Creates a new kill ring of the given size.
+     */
+    public KillRing(int size) {
+        slots = new String[size];
+    }
+
+    /**
+     * Creates a new kill ring of the default size. {@see DEFAULT_SIZE}.
+     */
+    public KillRing() {
+        this(DEFAULT_SIZE);
+    }
+
+    /**
+     * Resets the last-yank state.
+     */
+    public void resetLastYank() {
+        lastYank = false;
+    }
+
+    /**
+     * Resets the last-kill state.
+     */
+    public void resetLastKill() {
+        lastKill = false;
+    }
+
+    /**
+     * Returns {@code true} if the last command was a yank.
+     */
+    public boolean lastYank() {
+        return lastYank;
+    }
+
+    /**
+     * Adds the string to the kill-ring. Also sets lastYank to false
+     * and lastKill to true.
+     */
+    public void add(String str) {
+        lastYank = false;
+
+        if (lastKill) {
+            if (slots[head] != null) {
+                slots[head] += str;
+                return;
+            }
+        }
+
+        lastKill = true;
+        next();
+        slots[head] = str;
+    }
+
+    /**
+     * Adds the string to the kill-ring product of killing
+     * backwards. If the previous command was a kill text one then
+     * adds the text at the beginning of the previous kill to avoid
+     * that two consecutive backwards kills followed by a yank leaves
+     * things reversed.
+     */
+    public void addBackwards(String str) {
+        lastYank = false;
+
+        if (lastKill) {
+            if (slots[head] != null) {
+                slots[head] = str + slots[head];
+                return;
+            }
+        }
+
+        lastKill = true;
+        next();
+        slots[head] = str;
+    }
+
+    /**
+     * Yanks a previously killed text. Returns {@code null} if the
+     * ring is empty.
+     */
+    public String yank() {
+        lastKill = false;
+        lastYank = true;
+        return slots[head];
+    }
+
+    /**
+     * Moves the pointer to the current slot back and returns the text
+     * in that position. If the previous command was not yank returns
+     * null.
+     */
+    public String yankPop() {
+        lastKill = false;
+        if (lastYank) {
+            prev();
+            return slots[head];
+        }
+        return null;
+    }
+
+    /**
+     * Moves the pointer to the current slot forward. If the end of
+     * the slots is reached then points back to the beginning.
+     */
+    private void next() {
+        if (head == 0 && slots[0] == null) {
+            return;
+        }
+        head++;
+        if (head == slots.length) {
+            head = 0;
+        }
+    }
+
+    /**
+     * Moves the pointer to the current slot backwards. If the
+     * beginning of the slots is reached then traverses the slot
+     * backwards until one with not null content is found.
+     */
+    private void prev() {
+        head--;
+        if (head == -1) {
+            int x = (slots.length - 1);
+            for (; x >= 0; x--) {
+                if (slots[x] != null) {
+                    break;
+                }
+            }
+            head = x;
+        }
+    }
+}