/*

 * 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 java.lang.invoke.MethodHandles.Lookup;

import java.lang.reflect.AccessibleObject;

import java.lang.reflect.Field;

import static java.lang.invoke.MethodHandleNatives.Constants.*;

import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;

/**

 * The JVM interface for the method handles package is all here.

 * This is an interface internal and private to an implemetantion of JSR 292.

 * <em>This class is not part of the JSR 292 standard.</em>

 * @author jrose

 */

class MethodHandleNatives {

    private MethodHandleNatives() { } // static only

    /// MethodName support

    static native void init(MemberName self, Object ref);

    static native void expand(MemberName self);

    static native void resolve(MemberName self, Class<?> caller);

    static native int getMembers(Class<?> defc, String matchName, String matchSig,

            int matchFlags, Class<?> caller, int skip, MemberName[] results);

    /// MethodHandle support

    /** Initialize the method handle to adapt the call. */

    static native void init(AdapterMethodHandle self, MethodHandle target, int argnum);

    /** Initialize the method handle to call the correct method, directly. */

    static native void init(BoundMethodHandle self, Object target, int argnum);

    /** Initialize the method handle to call as if by an invoke* instruction. */

    static native void init(DirectMethodHandle self, Object ref, boolean doDispatch, Class<?> caller);

    /** Initialize a method type, once per form. */

    static native void init(MethodType self);

    /** Tell the JVM about a class's bootstrap method. */

    static native void registerBootstrap(Class<?> caller, MethodHandle bootstrapMethod);

    /** Ask the JVM about a class's bootstrap method. */

    static native MethodHandle getBootstrap(Class<?> caller);

    /** Tell the JVM that we need to change the target of an invokedynamic. */

    static native void setCallSiteTarget(CallSite site, MethodHandle target);

    /** Fetch the vmtarget field.

     *  It will be sanitized as necessary to avoid exposing non-Java references.

     *  This routine is for debugging and reflection.

     */

    static native Object getTarget(MethodHandle self, int format);

    /** Fetch the name of the handled method, if available.

     *  This routine is for debugging and reflection.

     */

    static MemberName getMethodName(MethodHandle self) {

        return (MemberName) getTarget(self, ETF_METHOD_NAME);

    }

    /** Fetch the reflective version of the handled method, if available.

     */

    static AccessibleObject getTargetMethod(MethodHandle self) {

        return (AccessibleObject) getTarget(self, ETF_REFLECT_METHOD);

    }

    /** Fetch the target of this method handle.

     *  If it directly targets a method, return a MemberName for the method.

     *  If it is chained to another method handle, return that handle.

     */

    static Object getTargetInfo(MethodHandle self) {

        return getTarget(self, ETF_HANDLE_OR_METHOD_NAME);

    }

    static Object[] makeTarget(Class<?> defc, String name, String sig, int mods, Class<?> refc) {

        return new Object[] { defc, name, sig, mods, refc };

    }

    /** Fetch MH-related JVM parameter.

     *  which=0 retrieves MethodHandlePushLimit

     *  which=1 retrieves stack slot push size (in address units)

     */

    static native int getConstant(int which);

    /** Java copy of MethodHandlePushLimit in range 2..255. */

    static final int JVM_PUSH_LIMIT;

    /** JVM stack motion (in words) after one slot is pushed, usually -1.

     */

    static final int JVM_STACK_MOVE_UNIT;

    /** Which conv-ops are implemented by the JVM? */

    static final int CONV_OP_IMPLEMENTED_MASK;

    /** Derived mode flag.  Only false on some old JVM implementations. */

    static final boolean HAVE_RICOCHET_FRAMES;

    private static native void registerNatives();

    static {

    }

    // All compile-time constants go here.

    // There is an opportunity to check them against the JVM's idea of them.

    static class Constants {

        Constants() { } // static only

        // MethodHandleImpl

        static final int // for getConstant

                GC_JVM_PUSH_LIMIT = 0,

                GC_JVM_STACK_MOVE_UNIT = 1,

        static final int

                ETF_HANDLE_OR_METHOD_NAME = 0, // all available data (immediate MH or method)

                ETF_DIRECT_HANDLE         = 1, // ultimate method handle (will be a DMH, may be self)

                ETF_METHOD_NAME           = 2, // ultimate method as MemberName

                ETF_REFLECT_METHOD        = 3; // ultimate method as java.lang.reflect object (sans refClass)

        // MemberName

        // The JVM uses values of -2 and above for vtable indexes.

        // Field values are simple positive offsets.

        // Ref: src/share/vm/oops/methodOop.hpp

        // This value is negative enough to avoid such numbers,

        // but not too negative.

        static final int

                MN_IS_METHOD           = 0x00010000, // method (not constructor)

                MN_IS_CONSTRUCTOR      = 0x00020000, // constructor

                MN_IS_FIELD            = 0x00040000, // field

                MN_IS_TYPE             = 0x00080000, // nested type

                MN_SEARCH_SUPERCLASSES = 0x00100000, // for MHN.getMembers

                MN_SEARCH_INTERFACES   = 0x00200000, // for MHN.getMembers

                VM_INDEX_UNINITIALIZED = -99;

        // BoundMethodHandle

        /** Constants for decoding the vmargslot field, which contains 2 values. */

        static final int

            ARG_SLOT_PUSH_SHIFT = 16,

            ARG_SLOT_MASK = (1<<ARG_SLOT_PUSH_SHIFT)-1;

        // AdapterMethodHandle

        /** Conversions recognized by the JVM.

         *  They must align with the constants in java.lang.invoke.AdapterMethodHandle,

         *  in the JVM file hotspot/src/share/vm/classfile/javaClasses.hpp.

         */

        static final int

            OP_RETYPE_ONLY   = 0x0, // no argument changes; straight retype

            OP_RETYPE_RAW    = 0x1, // straight retype, trusted (void->int, Object->T)

            OP_CHECK_CAST    = 0x2, // ref-to-ref conversion; requires a Class argument

            OP_PRIM_TO_PRIM  = 0x3, // converts from one primitive to another

            OP_REF_TO_PRIM   = 0x4, // unboxes a wrapper to produce a primitive

            OP_PRIM_TO_REF   = 0x5, // boxes a primitive into a wrapper

            OP_SWAP_ARGS     = 0x6, // swap arguments (vminfo is 2nd arg)

            OP_ROT_ARGS      = 0x7, // rotate arguments (vminfo is displaced arg)

            OP_DUP_ARGS      = 0x8, // duplicates one or more arguments (at TOS)

            OP_DROP_ARGS     = 0x9, // remove one or more argument slots

            OP_COLLECT_ARGS  = 0xA, // combine arguments using an auxiliary function

            OP_SPREAD_ARGS   = 0xB, // expand in place a varargs array (of known size)

            OP_FOLD_ARGS     = 0xC, // combine but do not remove arguments; prepend result

            //OP_UNUSED_13   = 0xD, // unused code, perhaps for reified argument lists

            CONV_OP_LIMIT    = 0xE; // limit of CONV_OP enumeration

        /** Shift and mask values for decoding the AMH.conversion field.

         *  These numbers are shared with the JVM for creating AMHs.

         */

        static final int

            CONV_OP_MASK     = 0xF00, // this nybble contains the conversion op field

            CONV_TYPE_MASK   = 0x0F,  // fits T_ADDRESS and below

            CONV_VMINFO_MASK = 0x0FF, // LSB is reserved for JVM use

            CONV_VMINFO_SHIFT     =  0, // position of bits in CONV_VMINFO_MASK

            CONV_OP_SHIFT         =  8, // position of bits in CONV_OP_MASK

            CONV_DEST_TYPE_SHIFT  = 12, // byte 2 has the adapter BasicType (if needed)

            CONV_SRC_TYPE_SHIFT   = 16, // byte 2 has the source BasicType (if needed)

            CONV_STACK_MOVE_SHIFT = 20, // high 12 bits give signed SP change

            CONV_STACK_MOVE_MASK  = (1 << (32 - CONV_STACK_MOVE_SHIFT)) - 1;

        /** Which conv-ops are implemented by the JVM? */

        static final int DEFAULT_CONV_OP_IMPLEMENTED_MASK =

                // Value to use if the corresponding JVM query fails.

                ((1<<OP_RETYPE_ONLY)

                |(1<<OP_RETYPE_RAW)

                |(1<<OP_CHECK_CAST)

                |(1<<OP_PRIM_TO_PRIM)

                |(1<<OP_REF_TO_PRIM)

                |(1<<OP_SWAP_ARGS)

                |(1<<OP_ROT_ARGS)

                |(1<<OP_DUP_ARGS)

                |(1<<OP_DROP_ARGS)

                //|(1<<OP_SPREAD_ARGS)

                );

        /**

         * Basic types as encoded in the JVM.  These code values are not

         * intended for use outside this class.  They are used as part of

         * a private interface between the JVM and this class.

         */

        static final int

            T_BOOLEAN  =  4,

            T_CHAR     =  5,

            T_FLOAT    =  6,

            T_DOUBLE   =  7,

            T_BYTE     =  8,

            T_SHORT    =  9,

            T_INT      = 10,

            T_LONG     = 11,

            T_OBJECT   = 12,

            //T_ARRAY    = 13

            T_VOID     = 14,

            //T_ADDRESS  = 15

            T_ILLEGAL  = 99;

        /**

         * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.

         */

        static final int

            REF_getField                = 1,

            REF_getStatic               = 2,

            REF_putField                = 3,

            REF_putStatic               = 4,

            REF_invokeVirtual           = 5,

            REF_invokeStatic            = 6,

            REF_invokeSpecial           = 7,

            REF_newInvokeSpecial        = 8,

            REF_invokeInterface         = 9;

    }

    private static native int getNamedCon(int which, Object[] name);

    static boolean verifyConstants() {

        Object[] box = { null };

        for (int i = 0; ; i++) {

            box[0] = null;

            int vmval = getNamedCon(i, box);

            if (box[0] == null)  break;

            String name = (String) box[0];

            try {

                Field con = Constants.class.getDeclaredField(name);

                int jval = con.getInt(null);

                if (jval == vmval)  continue;

                String err = (name+": JVM has "+vmval+" while Java has "+jval);

                if (name.equals("CONV_OP_LIMIT")) {

                    System.err.println("warning: "+err);

                    continue;

                }

                throw new InternalError(err);

            } catch (Exception ex) {

                if (ex instanceof NoSuchFieldException) {

                    String err = (name+": JVM has "+vmval+" which Java does not define");

                    // ignore exotic ops the JVM cares about; we just wont issue them

                    if (name.startsWith("OP_") || name.startsWith("GC_")) {

                        System.err.println("warning: "+err);

                        continue;

                    }

                }

                throw new InternalError(name+": access failed, got "+ex);

            }

        }

        return true;

    }

    static {

        assert(verifyConstants());

    }

    // Up-calls from the JVM.

    // These must NOT be public.

    /**

     * The JVM is linking an invokedynamic instruction.  Create a reified call site for it.

     */

    static CallSite makeDynamicCallSite(MethodHandle bootstrapMethod,

                                        String name, MethodType type,

                                        Object info,

                                        MemberName callerMethod, int callerBCI) {

        return CallSite.makeSite(bootstrapMethod, name, type, info, callerMethod, callerBCI);

    }

    /**

     * Called by the JVM to check the length of a spread array.

     */

    static void checkSpreadArgument(Object av, int n) {

        MethodHandleStatics.checkSpreadArgument(av, n);

    }

    /**

     * The JVM wants a pointer to a MethodType.  Oblige it by finding or creating one.

     */

    static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {

        return MethodType.makeImpl(rtype, ptypes, true);

    }

    /**

     * The JVM wants to use a MethodType with inexact invoke.  Give the runtime fair warning.

     */

    static void notifyGenericMethodType(MethodType type) {

        type.form().notifyGenericMethodType();

    }

    /**

     * The JVM wants to raise an exception.  Here's the path.

     */

    static void raiseException(int code, Object actual, Object required) {

        String message = null;

        switch (code) {

        case 190: // arraylength

            try {

                String reqLength = "";

                if (required instanceof AdapterMethodHandle) {

                    int conv = ((AdapterMethodHandle)required).getConversion();

                    int spChange = AdapterMethodHandle.extractStackMove(conv);

                    reqLength = " of length "+(spChange+1);

                }

                int actualLength = actual == null ? 0 : java.lang.reflect.Array.getLength(actual);

                message = "required array"+reqLength+", but encountered wrong length "+actualLength;

                break;

            } catch (IllegalArgumentException ex) {

            }

            required = Object[].class;  // should have been an array

            code = 192; // checkcast

            break;

        case 191: // athrow

            // JVM is asking us to wrap an exception which happened during resolving

            if (required == BootstrapMethodError.class) {

                throw new BootstrapMethodError((Throwable) actual);

            }

            break;

        }

        // disregard the identity of the actual object, if it is not a class:

        if (message == null) {

            if (!(actual instanceof Class) && !(actual instanceof MethodType))

                actual = actual.getClass();

           if (actual != null)

               message = "required "+required+" but encountered "+actual;

           else

               message = "required "+required;

        }

        switch (code) {

        case 190: // arraylength

            throw new ArrayIndexOutOfBoundsException(message);

        case 50: //_aaload

            throw new ClassCastException(message);

        case 192: // checkcast

            throw new ClassCastException(message);

        default:

            throw new InternalError("unexpected code "+code+": "+message);

        }

    }

    /**

     * The JVM is resolving a CONSTANT_MethodHandle CP entry.  And it wants our help.

     * It will make an up-call to this method.  (Do not change the name or signature.)

     */

    static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,

                                                 Class<?> defc, String name, Object type) {

        try {

            Lookup lookup = IMPL_LOOKUP.in(callerClass);

            return lookup.linkMethodHandleConstant(refKind, defc, name, type);

        } catch (ReflectiveOperationException ex) {

            Error err = new IncompatibleClassChangeError();

            err.initCause(ex);

            throw err;

        }

    }

    /**

     * This assertion marks code which was written before ricochet frames were implemented.

     * Such code will go away when the ports catch up.

     */

    static boolean workaroundWithoutRicochetFrames() {

        assert(!HAVE_RICOCHET_FRAMES) : "this code should not be executed if `-XX:+UseRicochetFrames is enabled";

        return true;

    }

}