/*

 * 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.util.ValueConversions;

import sun.invoke.util.Wrapper;

import java.lang.reflect.*;

import static java.lang.invoke.MethodHandleStatics.*;

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

/**

 * Adapters which mediate between incoming calls which are generic

 * and outgoing calls which are not.  Any call can be represented generically

 * boxing up its arguments, and (on return) unboxing the return value.

 * <p>

 * A call is "generic" (in MethodHandle terms) if its MethodType features

 * only Object arguments.  A non-generic call therefore features

 * primitives and/or reference types other than Object.

 * An adapter has types for its incoming and outgoing calls.

 * The incoming call type is simply determined by the adapter's type

 * (the MethodType it presents to callers).  The outgoing call type

 * is determined by the adapter's target (a MethodHandle that the adapter

 * either binds internally or else takes as a leading argument).

 * (To stretch the term, adapter-like method handles may have multiple

 * targets or be polymorphic across multiple call types.)

 * @author jrose

 */

class FromGeneric {

    // type for the outgoing call (may have primitives, etc.)

    private final MethodType targetType;

    // type of the outgoing call internal to the adapter

    private final MethodType internalType;

    // prototype adapter (clone and customize for each new target!)

    private final Adapter adapter;

    // entry point for adapter (Adapter mh, a...) => ...

    private final MethodHandle entryPoint;

    // unboxing invoker of type (MH, Object**N) => raw return value

    // it makes up the difference of internalType => targetType

    private final MethodHandle unboxingInvoker;

    // conversion which boxes a the target's raw return value

    private final MethodHandle returnConversion;

    /** Compute and cache information common to all unboxing adapters

     *  that can call out to targets of the erasure-family of the given erased type.

     */

    private FromGeneric(MethodType targetType) {

        this.targetType = targetType;

        MethodType internalType0;

        // the target invoker will generally need casts on reference arguments

        Adapter ad = findAdapter(internalType0 = targetType.erase());

        if (ad != null) {

            // Immediate hit to exactly the adapter we want,

            // with no monkeying around with primitive types.

            this.internalType = internalType0;

            this.adapter = ad;

            this.entryPoint = ad.prototypeEntryPoint();

            this.returnConversion = computeReturnConversion(targetType, internalType0);

            this.unboxingInvoker = computeUnboxingInvoker(targetType, internalType0);

            return;

        }

        // outgoing primitive arguments will be wrapped; unwrap them

        MethodType primsAsObj = targetType.form().primArgsAsBoxes();

        MethodType objArgsRawRet = primsAsObj.form().primsAsInts();

        if (objArgsRawRet != targetType)

            ad = findAdapter(internalType0 = objArgsRawRet);

        if (ad == null) {

            ad = buildAdapterFromBytecodes(internalType0 = targetType);

        }

        this.internalType = internalType0;

        this.adapter = ad;

        MethodType tepType = targetType.insertParameterTypes(0, adapter.getClass());

        this.entryPoint = ad.prototypeEntryPoint();

        this.returnConversion = computeReturnConversion(targetType, internalType0);

        this.unboxingInvoker = computeUnboxingInvoker(targetType, internalType0);

    }

    static {

        assert(MethodHandleNatives.workaroundWithoutRicochetFrames());  // this class is deprecated

    }

    /**

     * The typed target will be called according to targetType.

     * The adapter code will in fact see the raw result from internalType,

     * and must box it into an object.  Produce a converter for this.

     */

    private static MethodHandle computeReturnConversion(

            MethodType targetType, MethodType internalType) {

        Class<?> tret = targetType.returnType();

        Class<?> iret = internalType.returnType();

        Wrapper wrap = Wrapper.forBasicType(tret);

        if (!iret.isPrimitive()) {

            assert(iret == Object.class);

            return ValueConversions.identity();

        } else if (wrap.primitiveType() == iret) {

            return ValueConversions.box(wrap);

        } else {

            assert(tret == double.class ? iret == long.class : iret == int.class);

            return ValueConversions.boxRaw(wrap);

        }

    }

    /**

     * The typed target will need an exact invocation point; provide it here.

     * The adapter will possibly need to make a slightly different call,

     * so adapt the invoker.  This way, the logic for making up the

     * difference between what the adapter can call and what the target

     * needs can be cached once per type.

     */

    private static MethodHandle computeUnboxingInvoker(

            MethodType targetType, MethodType internalType) {

        // All the adapters we have here have reference-untyped internal calls.

        assert(internalType == internalType.erase());

        MethodHandle invoker = targetType.invokers().exactInvoker();

        // cast all narrow reference types, unbox all primitive arguments:

        MethodType fixArgsType = internalType.changeReturnType(targetType.returnType());

        MethodHandle fixArgs = MethodHandleImpl.convertArguments(

                                 invoker, Invokers.invokerType(fixArgsType),

                                 invoker.type(), 0);

        if (fixArgs == null)

            throw new InternalError("bad fixArgs");

        // reinterpret the calling sequence as raw:

        MethodHandle retyper = AdapterMethodHandle.makeRetypeRaw(

                                        Invokers.invokerType(internalType), fixArgs);

        if (retyper == null)

            throw new InternalError("bad retyper");

        return retyper;

    }

    Adapter makeInstance(MethodHandle typedTarget) {

        MethodType type = typedTarget.type();

        if (type == targetType) {

            return adapter.makeInstance(entryPoint, unboxingInvoker, returnConversion, typedTarget);

        }

        // my erased-type is not exactly the same as the desired type

        assert(type.erase() == targetType);  // else we are busted

        MethodHandle invoker = computeUnboxingInvoker(type, internalType);

        return adapter.makeInstance(entryPoint, invoker, returnConversion, typedTarget);

    }

    /** Build an adapter of the given generic type, which invokes typedTarget

     *  on the incoming arguments, after unboxing as necessary.

     *  The return value is boxed if necessary.

     * @param typedTarget the target

     * @return an adapter method handle

     */

    public static MethodHandle make(MethodHandle typedTarget) {

        MethodType type = typedTarget.type();

        if (type == type.generic())  return typedTarget;

        return FromGeneric.of(type).makeInstance(typedTarget);

    }

    /** Return the adapter information for this type's erasure. */

    static FromGeneric of(MethodType type) {

        MethodTypeForm form = type.form();

        FromGeneric fromGen = form.fromGeneric;

        if (fromGen == null)

            form.fromGeneric = fromGen = new FromGeneric(form.erasedType());

        return fromGen;

    }

    public String toString() {

        return "FromGeneric"+targetType;

    }

    /* Create an adapter that handles spreading calls for the given type. */

    static Adapter findAdapter(MethodType internalType) {

        MethodType entryType = internalType.generic();

        MethodTypeForm form = internalType.form();

        Class<?> rtype = internalType.returnType();

        int argc = form.parameterCount();

        int lac = form.longPrimitiveParameterCount();

        int iac = form.primitiveParameterCount() - lac;

        String intsAndLongs = (iac > 0 ? "I"+iac : "")+(lac > 0 ? "J"+lac : "");

        String rawReturn = String.valueOf(Wrapper.forPrimitiveType(rtype).basicTypeChar());

        String cname0 = rawReturn + argc;

        String cname1 = "A"       + argc;

        String[] cnames = { cname0+intsAndLongs, cname0, cname1+intsAndLongs, cname1 };

        String iname = "invoke_"+cname0+intsAndLongs;

        // e.g., D5I2, D5, L5I2, L5; invoke_D5

        for (String cname : cnames) {

            Class<? extends Adapter> acls = Adapter.findSubClass(cname);

            if (acls == null)  continue;

            // see if it has the required invoke method

            MethodHandle entryPoint = null;

            try {

                entryPoint = IMPL_LOOKUP.findSpecial(acls, iname, entryType, acls);

            } catch (ReflectiveOperationException ex) {

            }

            if (entryPoint == null)  continue;

            Constructor<? extends Adapter> ctor = null;

            try {

                ctor = acls.getDeclaredConstructor(MethodHandle.class);

            } catch (NoSuchMethodException ex) {

            } catch (SecurityException ex) {

            }

            if (ctor == null)  continue;

            try {

                // Produce an instance configured as a prototype.

                return ctor.newInstance(entryPoint);

            } catch (IllegalArgumentException ex) {

            } catch (InvocationTargetException wex) {

                Throwable ex = wex.getTargetException();

                if (ex instanceof Error)  throw (Error)ex;

                if (ex instanceof RuntimeException)  throw (RuntimeException)ex;

            } catch (InstantiationException ex) {

            } catch (IllegalAccessException ex) {

            }

        }

        return null;

    }

    static Adapter buildAdapterFromBytecodes(MethodType internalType) {

        throw new UnsupportedOperationException("NYI "+internalType);

    }

    /**

     * This adapter takes some untyped arguments, and returns an untyped result.

     * Internally, it applies the invoker to the target, which causes the

     * objects to be unboxed; the result is a raw type in L/I/J/F/D.

     * This result is passed to convert, which is responsible for

     * converting the raw result into a boxed object.

     * The invoker is kept separate from the target because it can be

     * generated once per type erasure family, and reused across adapters.

     */

    static abstract class Adapter extends BoundMethodHandle {

        /*

         * class X<<R,int N>> extends Adapter {

         *   (MH, Object**N)=>raw(R) invoker;

         *   (any**N)=>R target;

         *   raw(R)=>Object convert;

         *   Object invoke(Object**N a) = convert(invoker(target, a...))

         * }

         */

        protected final MethodHandle invoker;  // (MH, Object**N) => raw(R)

        protected final MethodHandle convert;  // raw(R) => Object

        protected final MethodHandle target;   // (any**N) => R

        @Override

            return addTypeString(target, this);

        }

        protected boolean isPrototype() { return target == null; }

        protected Adapter(MethodHandle entryPoint) {

            this(entryPoint, null, entryPoint, null);

            assert(isPrototype());

        }

        protected MethodHandle prototypeEntryPoint() {

            if (!isPrototype())  throw new InternalError();

            return convert;

        }

        protected Adapter(MethodHandle entryPoint,

                          MethodHandle invoker, MethodHandle convert, MethodHandle target) {

            super(entryPoint);

            this.invoker = invoker;

            this.convert = convert;

            this.target  = target;

        }

        /** Make a copy of self, with new fields. */

        protected abstract Adapter makeInstance(MethodHandle entryPoint,

                MethodHandle invoker, MethodHandle convert, MethodHandle target);

        // { return new ThisType(entryPoint, convert, target); }

        /// Conversions on the value returned from the target.

        protected Object convert_L(Object result) throws Throwable { return convert.invokeExact(result); }

        protected Object convert_I(int    result) throws Throwable { return convert.invokeExact(result); }

        protected Object convert_J(long   result) throws Throwable { return convert.invokeExact(result); }

        protected Object convert_F(float  result) throws Throwable { return convert.invokeExact(result); }

        protected Object convert_D(double result) throws Throwable { return convert.invokeExact(result); }

        static private final String CLASS_PREFIX; // "java.lang.invoke.FromGeneric$"

        static {

            String aname = Adapter.class.getName();

            String sname = Adapter.class.getSimpleName();

            if (!aname.endsWith(sname))  throw new InternalError();

            CLASS_PREFIX = aname.substring(0, aname.length() - sname.length());

        }

        /** Find a sibing class of Adapter. */

        static Class<? extends Adapter> findSubClass(String name) {

            String cname = Adapter.CLASS_PREFIX + name;

            try {

                return Class.forName(cname).asSubclass(Adapter.class);

            } catch (ClassNotFoundException ex) {

                return null;

            } catch (ClassCastException ex) {

                return null;

            }

        }

    }

    /* generated classes follow this pattern:

    static class xA2 extends Adapter {

        protected xA2(MethodHandle entryPoint) { super(entryPoint); }  // to build prototype

        protected xA2(MethodHandle e, MethodHandle i, MethodHandle c, MethodHandle t)

                        { super(e, i, c, t); }

        protected xA2 makeInstance(MethodHandle e, MethodHandle i, MethodHandle c, MethodHandle t)

                        { return new xA2(e, i, c, t); }

        protected Object invoke_L2(Object a0, Object a1) throws Throwable { return convert_L((Object)invoker.invokeExact(target, a0, a1)); }

        protected Object invoke_I2(Object a0, Object a1) throws Throwable { return convert_I((int)   invoker.invokeExact(target, a0, a1)); }

        protected Object invoke_J2(Object a0, Object a1) throws Throwable { return convert_J((long)  invoker.invokeExact(target, a0, a1)); }

        protected Object invoke_F2(Object a0, Object a1) throws Throwable { return convert_F((float) invoker.invokeExact(target, a0, a1)); }

        protected Object invoke_D2(Object a0, Object a1) throws Throwable { return convert_D((double)invoker.invokeExact(target, a0, a1)); }

    }

    // */

/*

: SHELL; n=FromGeneric; cp -p $n.java $n.java-; sed < $n.java- > $n.java+ -e '/{{*{{/,/}}*}}/w /tmp/genclasses.java' -e '/}}*}}/q'; (cd /tmp; javac -d . genclasses.java; java -cp . genclasses) >> $n.java+; echo '}' >> $n.java+; mv $n.java+ $n.java; mv $n.java- $n.java~

//{{{

import java.util.*;

class genclasses {

    static String[] TYPES = { "Object",    "int   ",    "long  ",    "float ",    "double" };

    static String[] WRAPS = { "         ", "(Integer)", "(Long)   ", "(Float)  ", "(Double) " };

    static String[] TCHARS = { "L",     "I",      "J",      "F",      "D",     "A" };

    static String[][] TEMPLATES = { {

        "@for@ arity=0..10  rcat<=4 nrefs<=99 nints=0   nlongs=0",

        "    //@each-cat@",

        "    static class @cat@ extends Adapter {",

        "        protected @cat@(MethodHandle entryPoint) { super(entryPoint); }  // to build prototype",

        "        protected @cat@(MethodHandle e, MethodHandle i, MethodHandle c, MethodHandle t)",

        "                        { super(e, i, c, t); }",

        "        protected @cat@ makeInstance(MethodHandle e, MethodHandle i, MethodHandle c, MethodHandle t)",

        "                        { return new @cat@(e, i, c, t); }",

        "        //@each-R@",

        "        protected Object invoke_@catN@(@Tvav@) throws Throwable { return convert_@Rc@((@R@)@W@invoker.invokeExact(target@av@)); }",

        "        //@end-R@",

        "    }",

    } };

    static final String NEWLINE_INDENT = "\n                ";

    enum VAR {

        cat, catN, R, Rc, W, av, Tvav, Ovav;

        public final String pattern = "@"+toString().replace('_','.')+"@";

        public String binding;

        static void makeBindings(boolean topLevel, int rcat, int nrefs, int nints, int nlongs) {

            int nargs = nrefs + nints + nlongs;

            if (topLevel)

                VAR.cat.binding = catstr(ALL_RETURN_TYPES ? TYPES.length : rcat, nrefs, nints, nlongs);

            VAR.catN.binding = catstr(rcat, nrefs, nints, nlongs);

            VAR.R.binding = TYPES[rcat];

            VAR.Rc.binding = TCHARS[rcat];

            VAR.W.binding = WRAPS[rcat];

            String[] Tv = new String[nargs];

            String[] av = new String[nargs];

            String[] Tvav = new String[nargs];

            String[] Ovav = new String[nargs];

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

                int tcat = (i < nrefs) ? 0 : (i < nrefs + nints) ? 1 : 2;

                Tv[i] = TYPES[tcat];

                av[i] = arg(i);

                Tvav[i] = param(Tv[i], av[i]);

                Ovav[i] = param("Object", av[i]);

            }

            VAR.av.binding = comma(", ", av);

            VAR.Tvav.binding = comma(Tvav);

            VAR.Ovav.binding = comma(Ovav);

        }

        static String arg(int i) { return "a"+i; }

        static String param(String t, String a) { return t+" "+a; }

        static String comma(String[] v) { return comma("", v); }

        static String comma(String sep, String[] v) {

            if (v.length == 0)  return "";

            String res = sep+v[0];

            for (int i = 1; i < v.length; i++)  res += ", "+v[i];

            return res;

        }

        static String transform(String string) {

            for (VAR var : values())

                string = string.replaceAll(var.pattern, var.binding);

            return string;

        }

    }

    static String[] stringsIn(String[] strings, int beg, int end) {

        return Arrays.copyOfRange(strings, beg, Math.min(end, strings.length));

    }

    static String[] stringsBefore(String[] strings, int pos) {

        return stringsIn(strings, 0, pos);

    }

    static String[] stringsAfter(String[] strings, int pos) {

        return stringsIn(strings, pos, strings.length);

    }

    static int indexAfter(String[] strings, int pos, String tag) {

        return Math.min(indexBefore(strings, pos, tag) + 1, strings.length);

    }

    static int indexBefore(String[] strings, int pos, String tag) {

        for (int i = pos, end = strings.length; ; i++) {

            if (i == end || strings[i].endsWith(tag))  return i;

        }

    }

    static int MIN_ARITY, MAX_ARITY, MAX_RCAT, MAX_REFS, MAX_INTS, MAX_LONGS;

    static boolean ALL_ARG_TYPES, ALL_RETURN_TYPES;

    static HashSet<String> done = new HashSet<String>();

    public static void main(String... av) {

        for (String[] template : TEMPLATES) {

            int forLinesLimit = indexBefore(template, 0, "@each-cat@");

            String[] forLines = stringsBefore(template, forLinesLimit);

            template = stringsAfter(template, forLinesLimit);

            for (String forLine : forLines)

                expandTemplate(forLine, template);

        }

    }

    static void expandTemplate(String forLine, String[] template) {

        String[] params = forLine.split("[^0-9]+");

        if (params[0].length() == 0)  params = stringsAfter(params, 1);

        System.out.println("//params="+Arrays.asList(params));

        int pcur = 0;

        MIN_ARITY = Integer.valueOf(params[pcur++]);

        MAX_ARITY = Integer.valueOf(params[pcur++]);

        MAX_RCAT  = Integer.valueOf(params[pcur++]);

        MAX_REFS  = Integer.valueOf(params[pcur++]);

        MAX_INTS  = Integer.valueOf(params[pcur++]);

        MAX_LONGS = Integer.valueOf(params[pcur++]);

        if (pcur != params.length)  throw new RuntimeException("bad extra param: "+forLine);

        if (MAX_RCAT >= TYPES.length)  MAX_RCAT = TYPES.length - 1;

        ALL_ARG_TYPES = (indexBefore(template, 0, "@each-Tv@") < template.length);

        ALL_RETURN_TYPES = (indexBefore(template, 0, "@each-R@") < template.length);

        for (int nargs = MIN_ARITY; nargs <= MAX_ARITY; nargs++) {

            for (int rcat = 0; rcat <= MAX_RCAT; rcat++) {

                expandTemplate(template, true, rcat, nargs, 0, 0);

                if (ALL_ARG_TYPES)  break;

                expandTemplateForPrims(template, true, rcat, nargs, 1, 1);

                if (ALL_RETURN_TYPES)  break;

            }

        }

    }

    static String catstr(int rcat, int nrefs, int nints, int nlongs) {

        int nargs = nrefs + nints + nlongs;

        String cat = TCHARS[rcat] + nargs;

        if (!ALL_ARG_TYPES)  cat += (nints==0?"":"I"+nints)+(nlongs==0?"":"J"+nlongs);

        return cat;

    }

    static void expandTemplateForPrims(String[] template, boolean topLevel, int rcat, int nargs, int minints, int minlongs) {

        for (int isLong = 0; isLong <= 1; isLong++) {

            for (int nprims = 1; nprims <= nargs; nprims++) {

                int nrefs = nargs - nprims;

                int nints = ((1-isLong) * nprims);

                int nlongs = (isLong * nprims);

                expandTemplate(template, topLevel, rcat, nrefs, nints, nlongs);

            }

        }

    }

    static void expandTemplate(String[] template, boolean topLevel,

                               int rcat, int nrefs, int nints, int nlongs) {

        int nargs = nrefs + nints + nlongs;

        if (nrefs > MAX_REFS || nints > MAX_INTS || nlongs > MAX_LONGS)  return;

        VAR.makeBindings(topLevel, rcat, nrefs, nints, nlongs);

        if (topLevel && !done.add(VAR.cat.binding)) {

            System.out.println("    //repeat "+VAR.cat.binding);

            return;

        }

        for (int i = 0; i < template.length; i++) {

            String line = template[i];

            if (line.endsWith("@each-cat@")) {

                // ignore

            } else if (line.endsWith("@each-R@")) {

                int blockEnd = indexAfter(template, i, "@end-R@");

                String[] block = stringsIn(template, i+1, blockEnd-1);

                for (int rcat1 = rcat; rcat1 <= MAX_RCAT; rcat1++)

                    expandTemplate(block, false, rcat1, nrefs, nints, nlongs);

                VAR.makeBindings(topLevel, rcat, nrefs, nints, nlongs);

                i = blockEnd-1; continue;

            } else if (line.endsWith("@each-Tv@")) {

                int blockEnd = indexAfter(template, i, "@end-Tv@");

                String[] block = stringsIn(template, i+1, blockEnd-1);

                expandTemplate(block, false, rcat, nrefs, nints, nlongs);

                expandTemplateForPrims(block, false, rcat, nargs, nints+1, nlongs+1);

                VAR.makeBindings(topLevel, rcat, nrefs, nints, nlongs);

                i = blockEnd-1; continue;

            } else {

                System.out.println(VAR.transform(line));

            }

        }

    }

}

//}}} */

//params=[0, 10, 4, 99, 0, 0]

    static class A0 extends Adapter {

        protected A0(MethodHandle entryPoint) { super(entryPoint); }  // to build prototype

        protected A0(MethodHandle e, MethodHandle i, MethodHandle c, MethodHandle t)

                        { super(e, i, c, t); }

        protected A0 makeInstance(MethodHandle e, MethodHandle i, MethodHandle c, MethodHandle t)

                        { return new A0(e, i, c, t); }

        protected Object invoke_L0() throws Throwable { return convert_L((Object)invoker.invokeExact(target)); }

        protected Object invoke_I0() throws Throwable { return convert_I((int)   invoker.invokeExact(target)); }

        protected Object invoke_J0() throws Throwable { return convert_J((long)  invoker.invokeExact(target)); }

        protected Object invoke_F0() throws Throwable { return convert_F((float) invoker.invokeExact(target)); }

        protected Object invoke_D0() throws Throwable { return convert_D((double)invoker.invokeExact(target)); }

    }

    static class A1 extends Adapter {

        protected A1(MethodHandle entryPoint) { super(entryPoint); }  // to build prototype

        protected A1(MethodHandle e, MethodHandle i, MethodHandle c, MethodHandle t)

                        { super(e, i, c, t); }

        protected A1 makeInstance(MethodHandle e, MethodHandle i, MethodHandle c, MethodHandle t)

                        { return new A1(e, i, c, t); }

        protected Object invoke_L1(Object a0) throws Throwable { return convert_L((Object)invoker.invokeExact(target, a0)); }

        protected Object invoke_I1(Object a0) throws Throwable { return convert_I((int)   invoker.invokeExact(target, a0)); }