--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/src/jdk.jshell/share/classes/jdk/jshell/SnippetEvent.java	Mon Oct 19 19:15:16 2015 +0200
@@ -0,0 +1,152 @@
+/*
+ * Copyright (c) 2015, 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 jdk.jshell;
+
+import jdk.jshell.Snippet.Status;
+
+/**
+ * A description of a change to a Snippet. These are generated by direct changes
+ * to state with {@link JShell#eval(java.lang.String) JShell.eval(String)} or
+ * {@link JShell#drop(jdk.jshell.PersistentSnippet) JShell.drop(PersistentSnippet)},
+ * or indirectly by these same methods as
+ * dependencies change or Snippets are overwritten. For direct changes, the
+ * {@link SnippetEvent#causeSnippet()} is <code>null</code>.
+ * <p>
+ * <code>SnippetEvent</code> is immutable: an access to
+ * any of its methods will always return the same result.
+ * and thus is thread-safe.
+ * @author Robert Field
+ */
+public class SnippetEvent {
+
+    SnippetEvent(Snippet snippet, Status previousStatus, Status status,
+            boolean isSignatureChange, Snippet causeSnippet,
+            String value, Exception exception) {
+        this.snippet = snippet;
+        this.previousStatus = previousStatus;
+        this.status = status;
+        this.isSignatureChange = isSignatureChange;
+        this.causeSnippet = causeSnippet;
+        this.value = value;
+        this.exception = exception;
+    }
+
+    private final Snippet snippet;
+    private final Status previousStatus;
+    private final Status status;
+    private final boolean isSignatureChange;
+    private final Snippet causeSnippet;
+    private final String value;
+    private final Exception exception;
+
+    /**
+     * The Snippet which has changed
+     * @return the return the Snippet whose <code>Status</code> has changed.
+     */
+    public Snippet snippet() {
+        return snippet;
+    }
+
+    /**
+     * The status before the transition. If this event describes a Snippet
+     * creation return {@link Snippet.Status#NONEXISTENT NONEXISTENT}.
+     * @return the previousStatus
+     */
+    public Status previousStatus() {
+        return previousStatus;
+    }
+
+    /**
+     * The after status. Note: this may be the same as the previous status (not
+     * all changes cause a <code>Status</code> change.
+     * @return the status
+     */
+    public Status status() {
+        return status;
+    }
+
+    /**
+     * Has the signature changed? Coming in or out of definition
+     * (status.isDefined) is always a signature change. An overwritten Snippet
+     * {@link jdk.jshell.Snippet.Status#OVERWRITTEN (status == OVERWRITTEN)}
+     * is always <code>false</code> as responsibility for the
+     * definition has passed to the overwriting definition.
+     * @return <code>true</code> if the signature changed.
+     */
+    public boolean isSignatureChange() {
+        return isSignatureChange;
+    }
+
+    /**
+     * Either the snippet whose change caused this update or
+     * <code>null</code>. This returns <code>null</code> if this change is the
+     * creation of a new Snippet via
+     * {@link jdk.jshell.JShell#eval(java.lang.String) eval} or it is the
+     * explicit drop of a Snippet with
+     * {@link jdk.jshell.JShell#drop(jdk.jshell.PersistentSnippet) drop}.
+     *
+     * @return the Snippet which caused this change or <code>null</code> if
+     * directly caused by an API action.
+     */
+    public Snippet causeSnippet() {
+        return causeSnippet;
+    }
+
+    /**
+     * An instance of {@link jdk.jshell.UnresolvedReferenceException}, if an unresolved reference was
+     * encountered, or an instance of {@link jdk.jshell.EvalException} if an exception was thrown
+     * during execution, otherwise <code>null</code>.
+     * @return the exception or <code>null</code>.
+     */
+    public Exception exception() {
+        return exception;
+    }
+
+    /**
+     * The result value of successful run. The value is null if not executed
+     * or an exception was thrown.
+     * @return the value or <code>null</code>.
+     */
+    public String value() {
+        return value;
+    }
+
+    /**
+     * Return a string representation of the event
+     * @return a descriptive representation of the SnippetEvent
+     */
+    @Override
+    public String toString() {
+        return "SnippetEvent(snippet=" + snippet +
+                ",previousStatus=" + previousStatus +
+                ",status=" + status +
+                ",isSignatureChange=" + isSignatureChange +
+                ",causeSnippet" + causeSnippet +
+                (value == null? "" : "value=" + value) +
+                (exception == null? "" : "exception=" + exception) +
+                ")";
+    }
+}