/*

 * 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 sun.dyn.util.VerifyType;

import sun.dyn.util.Wrapper;

import java.dyn.*;

/**

 * The flavor of method handle which emulates an invoke instruction

 * on a predetermined argument.  The JVM dispatches to the correct method

 * when the handle is created, not when it is invoked.

 * @author jrose

 */

public class BoundMethodHandle extends MethodHandle  {

    //MethodHandle vmtarget;           // next BMH or final DMH or methodOop

    private final Object argument;     // argument to insert

    private final int    vmargslot;    // position at which it is inserted

    // Constructors in this class *must* be package scoped or private.

    /** Bind a direct MH to its receiver (or first ref. argument).

     *  The JVM will pre-dispatch the MH if it is not already static.

     */

    BoundMethodHandle(DirectMethodHandle mh, Object argument) {

        super(Access.TOKEN, mh.type().dropParameterType(0));

        // check the type now, once for all:

        this.argument = checkReferenceArgument(argument, mh, 0);

        this.vmargslot = this.type().parameterSlotCount();

        if (MethodHandleNatives.JVM_SUPPORT) {

            this.vmtarget = null;  // maybe updated by JVM

            MethodHandleNatives.init(this, mh, 0);

        } else {

            this.vmtarget = mh;

        }

     }

    private static final int REF_ARG = 0, PRIM_ARG = 1, SELF_ARG = 2;

    /** Insert an argument into an arbitrary method handle.

     *  If argnum is zero, inserts the first argument, etc.

     *  The argument type must be a reference.

     */

    BoundMethodHandle(MethodHandle mh, Object argument, int argnum) {

        this(mh, argument, argnum, mh.type().parameterType(argnum).isPrimitive() ? PRIM_ARG : REF_ARG);

    }

    /** Insert an argument into an arbitrary method handle.

     *  If argnum is zero, inserts the first argument, etc.

     */

    BoundMethodHandle(MethodHandle mh, Object argument, int argnum, int whichArg) {

        super(Access.TOKEN, mh.type().dropParameterType(argnum));

        if (whichArg == PRIM_ARG)

            this.argument = bindPrimitiveArgument(argument, mh, argnum);

        else {

            if (whichArg == SELF_ARG)  argument = this;

            this.argument = checkReferenceArgument(argument, mh, argnum);

        }

        this.vmargslot = this.type().parameterSlotDepth(argnum);

        if (MethodHandleNatives.JVM_SUPPORT) {

            this.vmtarget = null;  // maybe updated by JVM

            MethodHandleNatives.init(this, mh, argnum);

        } else {

            this.vmtarget = mh;

        }

    }

    /** For the AdapterMethodHandle subclass.

     */

    BoundMethodHandle(MethodType type, Object argument, int vmargslot) {

        super(Access.TOKEN, type);

        this.argument = argument;

        this.vmargslot = vmargslot;

        assert(this.getClass() == AdapterMethodHandle.class);

    }

    /** Initialize the current object as a method handle, binding it

     *  as the {@code argnum}th argument of the method handle {@code entryPoint}.

     *  The invocation type of the resulting method handle will be the

     *  same as {@code entryPoint},  except that the {@code argnum}th argument

     *  type will be dropped.

     */

    public BoundMethodHandle(MethodHandle entryPoint, int argnum) {

        this(entryPoint, null, argnum, SELF_ARG);

        // Note:  If the conversion fails, perhaps because of a bad entryPoint,

        // the MethodHandle.type field will not be filled in, and therefore

        // no MH.invoke call will ever succeed.  The caller may retain a pointer

        // to the broken method handle, but no harm can be done with it.

    }

    /** Initialize the current object as a method handle, binding it

     *  as the first argument of the method handle {@code entryPoint}.

     *  The invocation type of the resulting method handle will be the

     *  same as {@code entryPoint},  except that the first argument

     *  type will be dropped.

     */

    public BoundMethodHandle(MethodHandle entryPoint) {

        this(entryPoint, null, 0, SELF_ARG);

    }

    /** Make sure the given {@code argument} can be used as {@code argnum}-th

     *  parameter of the given method handle {@code mh}, which must be a reference.

     *  <p>

     *  If this fails, throw a suitable {@code WrongMethodTypeException},

     *  which will prevent the creation of an illegally typed bound

     *  method handle.

     */

    final static Object checkReferenceArgument(Object argument, MethodHandle mh, int argnum) {

        Class<?> ptype = mh.type().parameterType(argnum);

        if (ptype.isPrimitive()) {

            // fail

        } else if (argument == null) {

            return null;

        } else if (VerifyType.isNullReferenceConversion(argument.getClass(), ptype)) {

            return argument;

        }

        throw badBoundArgumentException(argument, mh, argnum);

    }

    /** Make sure the given {@code argument} can be used as {@code argnum}-th

     *  parameter of the given method handle {@code mh}, which must be a primitive.

     *  <p>

     *  If this fails, throw a suitable {@code WrongMethodTypeException},

     *  which will prevent the creation of an illegally typed bound

     *  method handle.

     */

    final static Object bindPrimitiveArgument(Object argument, MethodHandle mh, int argnum) {

        Class<?> ptype = mh.type().parameterType(argnum);

        Wrapper  wrap = Wrapper.forPrimitiveType(ptype);

        Object   zero  = wrap.zero();

        if (zero == null) {

            // fail

        } else if (argument == null) {

            if (ptype != int.class && wrap.isSubwordOrInt())

                return Integer.valueOf(0);

            else

                return zero;

        } else if (VerifyType.isNullReferenceConversion(argument.getClass(), zero.getClass())) {

            if (ptype != int.class && wrap.isSubwordOrInt())

                return Wrapper.INT.wrap(argument);

            else

                return argument;

        }

        throw badBoundArgumentException(argument, mh, argnum);

    }

    final static RuntimeException badBoundArgumentException(Object argument, MethodHandle mh, int argnum) {

        String atype = (argument == null) ? "null" : argument.getClass().toString();

        return new WrongMethodTypeException("cannot bind "+atype+" argument to parameter #"+argnum+" of "+mh.type());

    }

    @Override

    public String toString() {

        return "Bound[" + super.toString() + "]";

    }

}