/* * Copyright (c) 2008, 2011, 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.lang.invoke; import sun.invoke.empty.Empty;import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP; /** * Construction and caching of often-used invokers. * @author jrose */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;     // erased (partially untyped but with primitives) invoker for the outgoing call    private /*lazy*/ MethodHandle erasedInvoker;    /*lazy*/ MethodHandle erasedInvokerWithDrops;  // for InvokeGeneric     // general invoker for the outgoing call    private /*lazy*/ MethodHandle generalInvoker;     // general invoker for the outgoing call, uses varargs    private /*lazy*/ MethodHandle varargsInvoker;     // general invoker for the outgoing call; accepts a trailing Object[]    private final /*lazy*/ MethodHandle[] spreadInvokers;     // invoker for an unbound callsite    private /*lazy*/ MethodHandle uninitializedCallSite;     /** Compute and cache information common to all collecting adapters     *  that implement members of the erasure-family of the given erased type.     */    /*non-public*/ Invokers(MethodType targetType) {        this.targetType = targetType;        this.spreadInvokers = new MethodHandle[targetType.parameterCount()+1];    }     /*non-public*/ static MethodType invokerType(MethodType targetType) {        return targetType.insertParameterTypes(0, MethodHandle.class);    }     /*non-public*/ MethodHandle exactInvoker() {        MethodHandle invoker = exactInvoker;        if (invoker != null)  return invoker;        invoker = lookupInvoker("invokeExact");        exactInvoker = invoker;        return invoker;    }     /*non-public*/ MethodHandle generalInvoker() {        MethodHandle invoker = generalInvoker;        if (invoker != null)  return invoker;        invoker = lookupInvoker("invoke");        generalInvoker = invoker;        return invoker;    }     private MethodHandle lookupInvoker(String name) {        MethodHandle invoker;        try {            invoker = IMPL_LOOKUP.findVirtual(MethodHandle.class, name, targetType);        } catch (ReflectiveOperationException ex) {            throw new InternalError("JVM cannot find invoker for "+targetType);        }        assert(invokerType(targetType) == invoker.type());        assert(!invoker.isVarargsCollector());        return invoker;    }     /*non-public*/ MethodHandle erasedInvoker() {        MethodHandle xinvoker = exactInvoker();        MethodHandle invoker = erasedInvoker;        if (invoker != null)  return invoker;        MethodType erasedType = targetType.erase();        invoker = xinvoker.asType(invokerType(erasedType));        erasedInvoker = invoker;        return invoker;    }     /*non-public*/ MethodHandle spreadInvoker(int leadingArgCount) {        MethodHandle vaInvoker = spreadInvokers[leadingArgCount];        if (vaInvoker != null)  return vaInvoker;        MethodHandle gInvoker = generalInvoker();        int spreadArgCount = targetType.parameterCount() - leadingArgCount;        vaInvoker = gInvoker.asSpreader(Object[].class, spreadArgCount);        spreadInvokers[leadingArgCount] = vaInvoker;        return vaInvoker;    }     /*non-public*/ MethodHandle varargsInvoker() {        MethodHandle vaInvoker = varargsInvoker;        if (vaInvoker != null)  return vaInvoker;        vaInvoker = spreadInvoker(0).asType(invokerType(MethodType.genericMethodType(0, true)));        varargsInvoker = vaInvoker;        return vaInvoker;    }     private static MethodHandle THROW_UCS = null;     /*non-public*/ MethodHandle uninitializedCallSite() {        MethodHandle invoker = uninitializedCallSite;        if (invoker != null)  return invoker;        if (targetType.parameterCount() > 0) {            MethodType type0 = targetType.dropParameterTypes(0, targetType.parameterCount());            Invokers invokers0 = type0.invokers();            invoker = MethodHandles.dropArguments(invokers0.uninitializedCallSite(),                                                  0, targetType.parameterList());            assert(invoker.type().equals(targetType));            uninitializedCallSite = invoker;            return invoker;        }        if (THROW_UCS == null) {            try {                THROW_UCS = IMPL_LOOKUP                    .findStatic(CallSite.class, "uninitializedCallSite",                                MethodType.methodType(Empty.class));            } catch (ReflectiveOperationException ex) {                throw new RuntimeException(ex);            }        }        invoker = AdapterMethodHandle.makeRetypeRaw(targetType, THROW_UCS);        assert(invoker.type().equals(targetType));        uninitializedCallSite = invoker;        return invoker;    }     public String toString() {        return "Invokers"+targetType;    }}