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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * accompanied this code).
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 *
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package java.lang.invoke;

import jdk.internal.vm.annotation.Stable;
import sun.invoke.util.ValueConversions;

import java.util.ArrayList;
import java.util.List;

import static java.lang.invoke.LambdaForm.BasicType;
import static java.lang.invoke.LambdaForm.BasicType.*;
import static java.lang.invoke.LambdaForm.BasicType.V_TYPE_NUM;
import static java.lang.invoke.LambdaForm.BasicType.V_TYPE_NUM;
import static java.lang.invoke.LambdaForm.BasicType.V_TYPE_NUM;
import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
import static java.lang.invoke.MethodHandleNatives.Constants.*;
import static java.lang.invoke.MethodHandleStatics.newInternalError;
import static java.lang.invoke.MethodHandleStatics.uncaughtException;

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.
All bound arguments are encapsulated in dedicated species.
/**
 * 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.
 *
 * All bound arguments are encapsulated in dedicated species.
 */
/*non-public*/ abstract class BoundMethodHandle extends MethodHandle {

    /*non-public*/ BoundMethodHandle(MethodType type, LambdaForm form) {
        super(type, form);
        assert(speciesData() == speciesDataFor(form));
    }

    //
    // BMH API and internals
    //

    static BoundMethodHandle bindSingle(MethodType type, LambdaForm form, BasicType xtype, Object x) {
        // for some type signatures, there exist pre-defined concrete BMH classes
        try {
            switch (xtype) {
            case L_TYPE:
                return bindSingle(type, form, x);  // Use known fast path.
            case I_TYPE:
                return (BoundMethodHandle) SPECIALIZER.topSpecies().extendWith(I_TYPE_NUM).factory().invokeBasic(type, form, ValueConversions.widenSubword(x));
            case J_TYPE:
                return (BoundMethodHandle) SPECIALIZER.topSpecies().extendWith(J_TYPE_NUM).factory().invokeBasic(type, form, (long) x);
            case F_TYPE:
                return (BoundMethodHandle) SPECIALIZER.topSpecies().extendWith(F_TYPE_NUM).factory().invokeBasic(type, form, (float) x);
            case D_TYPE:
                return (BoundMethodHandle) SPECIALIZER.topSpecies().extendWith(D_TYPE_NUM).factory().invokeBasic(type, form, (double) x);
            default : throw newInternalError("unexpected xtype: " + xtype);
            }
        } catch (Throwable t) {
            throw uncaughtException(t);
        }
    }

    /*non-public*/
    LambdaFormEditor editor() {
        return form.editor();
    }

    static BoundMethodHandle bindSingle(MethodType type, LambdaForm form, Object x) {
        return Species_L.make(type, form, x);
    }

    @Override // there is a default binder in the super class, for 'L' types only
    /*non-public*/
    BoundMethodHandle bindArgumentL(int pos, Object value) {
        return editor().bindArgumentL(this, pos, value);
    }

    /*non-public*/
    BoundMethodHandle bindArgumentI(int pos, int value) {
        return editor().bindArgumentI(this, pos, value);
    }
    /*non-public*/
    BoundMethodHandle bindArgumentJ(int pos, long value) {
        return editor().bindArgumentJ(this, pos, value);
    }
    /*non-public*/
    BoundMethodHandle bindArgumentF(int pos, float value) {
        return editor().bindArgumentF(this, pos, value);
    }
    /*non-public*/
    BoundMethodHandle bindArgumentD(int pos, double value) {
        return editor().bindArgumentD(this, pos, value);
    }
    @Override
    BoundMethodHandle rebind() {
        if (!tooComplex()) {
            return this;
        }
        return makeReinvoker(this);
    }

    private boolean tooComplex() {
        return (fieldCount() > FIELD_COUNT_THRESHOLD ||
                form.expressionCount() > FORM_EXPRESSION_THRESHOLD);
    }
    private static final int FIELD_COUNT_THRESHOLD = 12;      // largest convenient BMH field count
    private static final int FORM_EXPRESSION_THRESHOLD = 24;  // largest convenient BMH expression count

    
A reinvoker MH has this form: lambda (bmh, arg*) { thismh = bmh[0]; invokeBasic(thismh, arg*) } /**
     * A reinvoker MH has this form:
     * {@code lambda (bmh, arg*) { thismh = bmh[0]; invokeBasic(thismh, arg*) }}
     */
    static BoundMethodHandle makeReinvoker(MethodHandle target) {
        LambdaForm form = DelegatingMethodHandle.makeReinvokerForm(
                target, MethodTypeForm.LF_REBIND,
                Species_L.BMH_SPECIES, Species_L.BMH_SPECIES.getterFunction(0));
        return Species_L.make(target.type(), form, target);
    }

    
Return the SpeciesData instance representing this BMH species. All subclasses must provide a static field containing this value, and they must accordingly implement this method. /**
     * Return the {@link BoundMethodHandle.SpeciesData} instance representing this BMH species. All subclasses must provide a
     * static field containing this value, and they must accordingly implement this method.
     */
    /*non-public*/ abstract BoundMethodHandle.SpeciesData speciesData();

    /*non-public*/ static BoundMethodHandle.SpeciesData speciesDataFor(LambdaForm form) {
        Object c = form.names[0].constraint;
        if (c instanceof SpeciesData) {
            return (SpeciesData) c;
        }
        // if there is no BMH constraint, then use the null constraint
        return SPECIALIZER.topSpecies();
    }

    
Return the number of fields in this BMH.  Equivalent to speciesData().fieldCount().
/**
     * Return the number of fields in this BMH.  Equivalent to speciesData().fieldCount().
     */
    /*non-public*/ final int fieldCount() { return speciesData().fieldCount(); }

    @Override
    Object internalProperties() {
        return "\n& BMH="+internalValues();
    }

    @Override
    final String internalValues() {
        int count = fieldCount();
        if (count == 1) {
            return "[" + arg(0) + "]";
        }
        StringBuilder sb = new StringBuilder("[");
        for (int i = 0; i < count; ++i) {
            sb.append("\n  ").append(i).append(": ( ").append(arg(i)).append(" )");
        }
        return sb.append("\n]").toString();
    }

    /*non-public*/ final Object arg(int i) {
        try {
            Class<?> fieldType = speciesData().fieldTypes().get(i);
            switch (BasicType.basicType(fieldType)) {
                case L_TYPE: return          speciesData().getter(i).invokeBasic(this);
                case I_TYPE: return (int)    speciesData().getter(i).invokeBasic(this);
                case J_TYPE: return (long)   speciesData().getter(i).invokeBasic(this);
                case F_TYPE: return (float)  speciesData().getter(i).invokeBasic(this);
                case D_TYPE: return (double) speciesData().getter(i).invokeBasic(this);
            }
        } catch (Throwable ex) {
            throw uncaughtException(ex);
        }
        throw new InternalError("unexpected type: " + speciesData().key()+"."+i);
    }

    //
    // cloning API
    //

    /*non-public*/ abstract BoundMethodHandle copyWith(MethodType mt, LambdaForm lf);
    /*non-public*/ abstract BoundMethodHandle copyWithExtendL(MethodType mt, LambdaForm lf, Object narg);
    /*non-public*/ abstract BoundMethodHandle copyWithExtendI(MethodType mt, LambdaForm lf, int    narg);
    /*non-public*/ abstract BoundMethodHandle copyWithExtendJ(MethodType mt, LambdaForm lf, long   narg);
    /*non-public*/ abstract BoundMethodHandle copyWithExtendF(MethodType mt, LambdaForm lf, float  narg);
    /*non-public*/ abstract BoundMethodHandle copyWithExtendD(MethodType mt, LambdaForm lf, double narg);

    //
    // concrete BMH classes required to close bootstrap loops
    //

    private  // make it private to force users to access the enclosing class first
    static final class Species_L extends BoundMethodHandle {

        final Object argL0;

        private Species_L(MethodType mt, LambdaForm lf, Object argL0) {
            super(mt, lf);
            this.argL0 = argL0;
        }

        @Override
        /*non-public*/ SpeciesData speciesData() {
            return BMH_SPECIES;
        }

        /*non-public*/ static @Stable SpeciesData BMH_SPECIES;

        /*non-public*/ static BoundMethodHandle make(MethodType mt, LambdaForm lf, Object argL0) {
            return new Species_L(mt, lf, argL0);
        }
        @Override
        /*non-public*/ final BoundMethodHandle copyWith(MethodType mt, LambdaForm lf) {
            return new Species_L(mt, lf, argL0);
        }
        @Override
        /*non-public*/ final BoundMethodHandle copyWithExtendL(MethodType mt, LambdaForm lf, Object narg) {
            try {
                return (BoundMethodHandle) BMH_SPECIES.extendWith(L_TYPE_NUM).factory().invokeBasic(mt, lf, argL0, narg);
            } catch (Throwable ex) {
                throw uncaughtException(ex);
            }
        }
        @Override
        /*non-public*/ final BoundMethodHandle copyWithExtendI(MethodType mt, LambdaForm lf, int narg) {
            try {
                return (BoundMethodHandle) BMH_SPECIES.extendWith(I_TYPE_NUM).factory().invokeBasic(mt, lf, argL0, narg);
            } catch (Throwable ex) {
                throw uncaughtException(ex);
            }
        }
        @Override
        /*non-public*/ final BoundMethodHandle copyWithExtendJ(MethodType mt, LambdaForm lf, long narg) {
            try {
                return (BoundMethodHandle) BMH_SPECIES.extendWith(J_TYPE_NUM).factory().invokeBasic(mt, lf, argL0, narg);
            } catch (Throwable ex) {
                throw uncaughtException(ex);
            }
        }
        @Override
        /*non-public*/ final BoundMethodHandle copyWithExtendF(MethodType mt, LambdaForm lf, float narg) {
            try {
                return (BoundMethodHandle) BMH_SPECIES.extendWith(F_TYPE_NUM).factory().invokeBasic(mt, lf, argL0, narg);
            } catch (Throwable ex) {
                throw uncaughtException(ex);
            }
        }
        @Override
        /*non-public*/ final BoundMethodHandle copyWithExtendD(MethodType mt, LambdaForm lf, double narg) {
            try {
                return (BoundMethodHandle) BMH_SPECIES.extendWith(D_TYPE_NUM).factory().invokeBasic(mt, lf, argL0, narg);
            } catch (Throwable ex) {
                throw uncaughtException(ex);
            }
        }
    }

    //
    // BMH species meta-data
    //

    /*non-public*/
    static final class SpeciesData extends ClassSpecializer<BoundMethodHandle, String, SpeciesData>.SpeciesData {
        // This array is filled in lazily, as new species come into being over time.
        @Stable final private SpeciesData[] extensions = new SpeciesData[ARG_TYPE_LIMIT];

        public SpeciesData(Specializer outer, String key) {
            outer.super(key);
        }

        @Override
        protected String deriveClassName() {
            String typeString = deriveTypeString();
            if (typeString.isEmpty()) {
                return SimpleMethodHandle.class.getName();
            }
            return BoundMethodHandle.class.getName() + "$Species_" + typeString;
        }

        @Override
        protected List<Class<?>> deriveFieldTypes(String key) {
            ArrayList<Class<?>> types = new ArrayList<>(key.length());
            for (int i = 0; i < key.length(); i++) {
                types.add(basicType(key.charAt(i)).basicTypeClass());
            }
            return types;
        }

        @Override
        protected String deriveTypeString() {
            // (If/when we have to add nominal types, just inherit the more complex default.)
            return key();
        }

        @Override
        protected MethodHandle deriveTransformHelper(MemberName transform, int whichtm) {
            if (whichtm == Specializer.TN_COPY_NO_EXTEND) {
                return factory();
            } else if (whichtm < ARG_TYPE_LIMIT) {
                return extendWith((byte) whichtm).factory();
            } else {
                throw newInternalError("bad transform");
            }
        }

        @Override
        protected <X> List<X> deriveTransformHelperArguments(MemberName transform, int whichtm, List<X> args, List<X> fields) {
            assert(verifyTHAargs(transform, whichtm, args, fields));
            // The rule is really simple:  Keep the first two arguments
            // the same, then put in the fields, then put any other argument.
            args.addAll(2, fields);
            return args;
        }

        private boolean verifyTHAargs(MemberName transform, int whichtm, List<?> args, List<?> fields) {
            assert(transform == Specializer.BMH_TRANSFORMS.get(whichtm));
            assert(args.size() == transform.getMethodType().parameterCount());
            assert(fields.size() == this.fieldCount());
            final int MH_AND_LF = 2;
            if (whichtm == Specializer.TN_COPY_NO_EXTEND) {
                assert(transform.getMethodType().parameterCount() == MH_AND_LF);
            } else if (whichtm < ARG_TYPE_LIMIT) {
                assert(transform.getMethodType().parameterCount() == MH_AND_LF+1);
                final BasicType type = basicType((byte) whichtm);
                assert(transform.getParameterTypes()[MH_AND_LF] == type.basicTypeClass());
            } else {
                return false;
            }
            return true;
        }

        /*non-public*/ SpeciesData extendWith(byte typeNum) {
            SpeciesData sd = extensions[typeNum];
            if (sd != null)  return sd;
            sd = SPECIALIZER.findSpecies(key() + BasicType.basicType(typeNum).basicTypeChar());
            extensions[typeNum] = sd;
            return sd;
        }
    }

    /*non-public*/
    static final Specializer SPECIALIZER = new Specializer();
    static {
        SimpleMethodHandle.BMH_SPECIES = BoundMethodHandle.SPECIALIZER.findSpecies("");
        Species_L.BMH_SPECIES = BoundMethodHandle.SPECIALIZER.findSpecies("L");
    }

    /*non-public*/
    static final class Specializer extends ClassSpecializer<BoundMethodHandle, String, SpeciesData> {

        private static final MemberName SPECIES_DATA_ACCESSOR;

        static {
            try {
                SPECIES_DATA_ACCESSOR = IMPL_LOOKUP.resolveOrFail(REF_invokeVirtual, BoundMethodHandle.class,
                        "speciesData", MethodType.methodType(BoundMethodHandle.SpeciesData.class));
            } catch (ReflectiveOperationException ex) {
                throw newInternalError("Bootstrap link error", ex);
            }
        }

        private Specializer() {
            super(  // Reified type parameters:
                    BoundMethodHandle.class, String.class, BoundMethodHandle.SpeciesData.class,
                    // Principal constructor type:
                    MethodType.methodType(void.class, MethodType.class, LambdaForm.class),
                    // Required linkage between class and species:
                    SPECIES_DATA_ACCESSOR,
                    "BMH_SPECIES",
                    BMH_TRANSFORMS);
        }

        @Override
        protected String topSpeciesKey() {
            return "";
        }

        @Override
        protected BoundMethodHandle.SpeciesData newSpeciesData(String key) {
            return new BoundMethodHandle.SpeciesData(this, key);
        }

        static final List<MemberName> BMH_TRANSFORMS;
        static final int TN_COPY_NO_EXTEND = V_TYPE_NUM;
        static {
            final Class<BoundMethodHandle> BMH = BoundMethodHandle.class;
            // copyWithExtendLIJFD + copyWith
            try {
                BMH_TRANSFORMS = List.of(
                        IMPL_LOOKUP.resolveOrFail(REF_invokeVirtual, BMH, "copyWithExtendL", MethodType.methodType(BMH, MethodType.class, LambdaForm.class, Object.class)),
                        IMPL_LOOKUP.resolveOrFail(REF_invokeVirtual, BMH, "copyWithExtendI", MethodType.methodType(BMH, MethodType.class, LambdaForm.class, int.class)),
                        IMPL_LOOKUP.resolveOrFail(REF_invokeVirtual, BMH, "copyWithExtendJ", MethodType.methodType(BMH, MethodType.class, LambdaForm.class, long.class)),
                        IMPL_LOOKUP.resolveOrFail(REF_invokeVirtual, BMH, "copyWithExtendF", MethodType.methodType(BMH, MethodType.class, LambdaForm.class, float.class)),
                        IMPL_LOOKUP.resolveOrFail(REF_invokeVirtual, BMH, "copyWithExtendD", MethodType.methodType(BMH, MethodType.class, LambdaForm.class, double.class)),
                        IMPL_LOOKUP.resolveOrFail(REF_invokeVirtual, BMH, "copyWith", MethodType.methodType(BMH, MethodType.class, LambdaForm.class))
                );
            } catch (ReflectiveOperationException ex) {
                throw newInternalError("Failed resolving copyWith methods", ex);
            }

            // as it happens, there is one transform per BasicType including V_TYPE
            assert(BMH_TRANSFORMS.size() == TYPE_LIMIT);
        }

        
Generation of concrete BMH classes.
A concrete BMH species is fit for binding a number of values adhering to a
given type pattern. Reference types are erased.
BMH species are cached by type pattern.
A BMH species has a number of fields with the concrete (possibly erased) types of
bound values. Setters are provided as an API in BMH. Getters are exposed as MHs,
which can be included as names in lambda forms.
/**
         * Generation of concrete BMH classes.
         *
         * A concrete BMH species is fit for binding a number of values adhering to a
         * given type pattern. Reference types are erased.
         *
         * BMH species are cached by type pattern.
         *
         * A BMH species has a number of fields with the concrete (possibly erased) types of
         * bound values. Setters are provided as an API in BMH. Getters are exposed as MHs,
         * which can be included as names in lambda forms.
         */
        class Factory extends ClassSpecializer<BoundMethodHandle, String, BoundMethodHandle.SpeciesData>.Factory {
            @Override
            protected String chooseFieldName(Class<?> type, int index) {
                return "arg" + super.chooseFieldName(type, index);
            }
        }

        @Override
        protected Factory makeFactory() {
            return new Factory();
        }
      }

    static SpeciesData speciesData_L()      { return Species_L.BMH_SPECIES; }
    static SpeciesData speciesData_LL()     { return SPECIALIZER.findSpecies("LL"); }
    static SpeciesData speciesData_LLL()    { return SPECIALIZER.findSpecies("LLL"); }
    static SpeciesData speciesData_LLLL()   { return SPECIALIZER.findSpecies("LLLL"); }
    static SpeciesData speciesData_LLLLL()  { return SPECIALIZER.findSpecies("LLLLL"); }
}