--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/sun/dyn/Invokers.java	Tue May 05 22:40:09 2009 -0700
@@ -0,0 +1,86 @@
+/*
+ * Copyright 2008-2009 Sun Microsystems, Inc.  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.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package sun.dyn;
+
+import java.dyn.MethodHandle;
+import java.dyn.MethodHandles;
+import java.dyn.MethodType;
+
+
+/**
+ * Construction and caching of often-used invokers.
+ * @author jrose
+ */
+public class Invokers {
+    // exact type (sans leading taget MH) for the outgoing call
+    private final MethodType targetType;
+
+    // exact invoker for the outgoing call
+    private /*lazy*/ MethodHandle exactInvoker;
+
+    // generic (untyped) invoker for the outgoing call
+    private /*lazy*/ MethodHandle genericInvoker;
+
+    /** Compute and cache information common to all collecting adapters
+     *  that implement members of the erasure-family of the given erased type.
+     */
+    public Invokers(Access token, MethodType targetType) {
+        Access.check(token);
+        this.targetType = targetType;
+    }
+
+    public static MethodType invokerType(MethodType targetType) {
+        return targetType.insertParameterType(0, MethodHandle.class);
+    }
+
+    public MethodHandle exactInvoker() {
+        MethodHandle invoker = exactInvoker;
+        if (invoker != null)  return invoker;
+        invoker = MethodHandleImpl.IMPL_LOOKUP.findVirtual(MethodHandle.class, "invoke", targetType);
+        if (invoker == null)  throw new InternalError("JVM cannot find invoker for "+targetType);
+        assert(invokerType(targetType) == invoker.type());
+        exactInvoker = invoker;
+        return invoker;
+    }
+
+    public MethodHandle genericInvoker() {
+        MethodHandle invoker1 = exactInvoker();
+        MethodHandle invoker = genericInvoker;
+        if (invoker != null)  return invoker;
+        MethodType genericType = targetType.generic();
+        invoker = MethodHandles.convertArguments(invoker1, invokerType(genericType));
+        genericInvoker = invoker;
+        return invoker;
+    }
+
+    public MethodHandle varargsInvoker() {
+        throw new UnsupportedOperationException("NYI");
+    }
+
+    public String toString() {
+        return "Invokers"+targetType;
+    }
+}