/*

 * Copyright (c) 2010, 2013, 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 jdk.nashorn.internal.runtime.linker;

import static jdk.internal.org.objectweb.asm.Opcodes.ACC_FINAL;

import static jdk.internal.org.objectweb.asm.Opcodes.ACC_PRIVATE;

import static jdk.internal.org.objectweb.asm.Opcodes.ACC_PUBLIC;

import static jdk.internal.org.objectweb.asm.Opcodes.ACC_STATIC;

import static jdk.internal.org.objectweb.asm.Opcodes.ACC_SUPER;

import static jdk.internal.org.objectweb.asm.Opcodes.ACC_VARARGS;

import static jdk.internal.org.objectweb.asm.Opcodes.ACONST_NULL;

import static jdk.internal.org.objectweb.asm.Opcodes.ALOAD;

import static jdk.internal.org.objectweb.asm.Opcodes.ASTORE;

import static jdk.internal.org.objectweb.asm.Opcodes.DUP;

import static jdk.internal.org.objectweb.asm.Opcodes.IFNONNULL;

import static jdk.internal.org.objectweb.asm.Opcodes.ILOAD;

import static jdk.internal.org.objectweb.asm.Opcodes.ISTORE;

import static jdk.internal.org.objectweb.asm.Opcodes.POP;

import static jdk.internal.org.objectweb.asm.Opcodes.RETURN;

import static jdk.nashorn.internal.lookup.Lookup.MH;

import static jdk.nashorn.internal.runtime.linker.AdaptationResult.Outcome.ERROR_NO_ACCESSIBLE_CONSTRUCTOR;

import java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodType;

import java.lang.reflect.AccessibleObject;

import java.lang.reflect.Constructor;

import java.lang.reflect.Method;

import java.lang.reflect.Modifier;

import java.security.AccessControlContext;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.util.Arrays;

import java.util.Collection;

import java.util.HashSet;

import java.util.Iterator;

import java.util.List;

import java.util.Set;

import jdk.internal.org.objectweb.asm.ClassWriter;

import jdk.internal.org.objectweb.asm.Label;

import jdk.internal.org.objectweb.asm.Opcodes;

import jdk.internal.org.objectweb.asm.Type;

import jdk.internal.org.objectweb.asm.commons.InstructionAdapter;

import jdk.nashorn.internal.runtime.Context;

import jdk.nashorn.internal.runtime.ScriptFunction;

import jdk.nashorn.internal.runtime.ScriptObject;

import sun.reflect.CallerSensitive;

/**

 * Generates bytecode for a Java adapter class. Used by the {@link JavaAdapterFactory}.

 * </p><p>

 * For every protected or public constructor in the extended class, the adapter class will have between one to three

 * public constructors (visibility of protected constructors in the extended class is promoted to public).

 * <ul>

 * <li>In every case, a constructor taking a trailing ScriptObject argument preceded by original constructor arguments

 * is always created on the adapter class. When such a constructor is invoked, the passed ScriptObject's member

 * functions are used to implement and/or override methods on the original class, dispatched by name. A single

 * JavaScript function will act as the implementation for all overloaded methods of the same name. When methods on an

 * adapter instance are invoked, the functions are invoked having the ScriptObject passed in the instance constructor as

 * their "this". Subsequent changes to the ScriptObject (reassignment or removal of its functions) are not reflected in

 * the adapter instance; the method implementations are bound to functions at constructor invocation time.

 * {@code java.lang.Object} methods {@code equals}, {@code hashCode}, and {@code toString} can also be overridden. The

 * only restriction is that since every JavaScript object already has a {@code toString} function through the

 * {@code Object.prototype}, the {@code toString} in the adapter is only overridden if the passed ScriptObject has a

 * {@code toString} function as its own property, and not inherited from a prototype. All other adapter methods can be

 * implemented or overridden through a prototype-inherited function of the ScriptObject passed to the constructor too.

 * </li>

 * <li>

 * If the original types collectively have only one abstract method, or have several of them, but all share the

 * same name, an additional constructor is provided for every original constructor; this one takes a ScriptFunction as

 * its last argument preceded by original constructor arguments. This constructor will use the passed function as the

 * implementation for all abstract methods. For consistency, any concrete methods sharing the single abstract method

 * name will also be overridden by the function. When methods on the adapter instance are invoked, the ScriptFunction is

 * invoked with {@code null} as its "this".

 * </li>

 * <li>

 * If the adapter being generated can have class-level overrides, constructors taking same arguments as the superclass

 * constructors are also created. These constructors simply delegate to the superclass constructor. They are used to

 * create instances of the adapter class with no instance-level overrides.

 * </li>

 * </ul>

 * </p><p>

 * For adapter methods that return values, all the JavaScript-to-Java conversions supported by Nashorn will be in effect

 * to coerce the JavaScript function return value to the expected Java return type.

 * </p><p>

 * Since we are adding a trailing argument to the generated constructors in the adapter class, they will never be

 * declared as variable arity, even if the original constructor in the superclass was declared as variable arity. The

 * reason we are passing the additional argument at the end of the argument list instead at the front is that the

 * source-level script expression <code>new X(a, b) { ... }</code> (which is a proprietary syntax extension Nashorn uses

 * to resemble Java anonymous classes) is actually equivalent to <code>new X(a, b, { ... })</code>.

 * </p><p>

 * It is possible to create two different classes: those that can have both class-level and instance-level overrides,

 * and those that can only have instance-level overrides. When

 * {@link JavaAdapterFactory#getAdapterClassFor(Class[], ScriptObject)} is invoked with non-null {@code classOverrides}

 * parameter, an adapter class is created that can have class-level overrides, and the passed script object will be used

 * as the implementations for its methods, just as in the above case of the constructor taking a script object. Note

 * that in the case of class-level overrides, a new adapter class is created on every invocation, and the implementation

 * object is bound to the class, not to any instance. All created instances will share these functions. Of course, when

 * instances of such a class are being created, they can still take another object (or possibly a function) in their

 * constructor's trailing position and thus provide further instance-specific overrides. The order of invocation is

 * always instance-specified method, then a class-specified method, and finally the superclass method.

 */

final class JavaAdapterBytecodeGenerator {

    static final Type CONTEXT_TYPE       = Type.getType(Context.class);

    static final Type OBJECT_TYPE        = Type.getType(Object.class);

    static final Type SCRIPT_OBJECT_TYPE = Type.getType(ScriptObject.class);

    static final String CONTEXT_TYPE_NAME = CONTEXT_TYPE.getInternalName();

    static final String OBJECT_TYPE_NAME  = OBJECT_TYPE.getInternalName();

    static final String INIT = "<init>";

    static final String GLOBAL_FIELD_NAME = "global";

    static final String SCRIPT_OBJECT_TYPE_DESCRIPTOR = SCRIPT_OBJECT_TYPE.getDescriptor();

    static final String SET_GLOBAL_METHOD_DESCRIPTOR = Type.getMethodDescriptor(Type.VOID_TYPE, SCRIPT_OBJECT_TYPE);

    static final String VOID_NOARG_METHOD_DESCRIPTOR = Type.getMethodDescriptor(Type.VOID_TYPE);

    private static final Type SCRIPT_FUNCTION_TYPE = Type.getType(ScriptFunction.class);

    private static final Type STRING_TYPE = Type.getType(String.class);

    private static final Type METHOD_TYPE_TYPE = Type.getType(MethodType.class);

    private static final Type METHOD_HANDLE_TYPE = Type.getType(MethodHandle.class);

    private static final String GET_HANDLE_OBJECT_DESCRIPTOR = Type.getMethodDescriptor(METHOD_HANDLE_TYPE,

            OBJECT_TYPE, STRING_TYPE, METHOD_TYPE_TYPE);

    private static final String GET_HANDLE_FUNCTION_DESCRIPTOR = Type.getMethodDescriptor(METHOD_HANDLE_TYPE,

            SCRIPT_FUNCTION_TYPE, METHOD_TYPE_TYPE);

    private static final String GET_CLASS_INITIALIZER_DESCRIPTOR = Type.getMethodDescriptor(SCRIPT_OBJECT_TYPE);

    private static final Type RUNTIME_EXCEPTION_TYPE = Type.getType(RuntimeException.class);

    private static final Type THROWABLE_TYPE = Type.getType(Throwable.class);

    private static final Type UNSUPPORTED_OPERATION_TYPE = Type.getType(UnsupportedOperationException.class);

    private static final String SERVICES_CLASS_TYPE_NAME = Type.getInternalName(JavaAdapterServices.class);

    private static final String RUNTIME_EXCEPTION_TYPE_NAME = RUNTIME_EXCEPTION_TYPE.getInternalName();

    private static final String ERROR_TYPE_NAME = Type.getInternalName(Error.class);

    private static final String THROWABLE_TYPE_NAME = THROWABLE_TYPE.getInternalName();

    private static final String UNSUPPORTED_OPERATION_TYPE_NAME = UNSUPPORTED_OPERATION_TYPE.getInternalName();

    private static final String METHOD_HANDLE_TYPE_DESCRIPTOR = METHOD_HANDLE_TYPE.getDescriptor();

    private static final String GET_GLOBAL_METHOD_DESCRIPTOR = Type.getMethodDescriptor(SCRIPT_OBJECT_TYPE);

    private static final String GET_CLASS_METHOD_DESCRIPTOR = Type.getMethodDescriptor(Type.getType(Class.class));

    // Package used when the adapter can't be defined in the adaptee's package (either because it's sealed, or because

    // it's a java.* package.

    private static final String ADAPTER_PACKAGE_PREFIX = "jdk/nashorn/javaadapters/";

    // Class name suffix used to append to the adaptee class name, when it can be defined in the adaptee's package.

    private static final String ADAPTER_CLASS_NAME_SUFFIX = "$$NashornJavaAdapter";

    private static final String JAVA_PACKAGE_PREFIX = "java/";

    private static final int MAX_GENERATED_TYPE_NAME_LENGTH = 255;

    private static final String CLASS_INIT = "<clinit>";

    private static final String STATIC_GLOBAL_FIELD_NAME = "staticGlobal";

    /**

     * Collection of methods we never override: Object.clone(), Object.finalize().

     */

    private static final Collection<MethodInfo> EXCLUDED = getExcludedMethods();

    // This is the superclass for our generated adapter.

    private final Class<?> superClass;

    // Class loader used as the parent for the class loader we'll create to load the generated class. It will be a class

    // loader that has the visibility of all original types (class to extend and interfaces to implement) and of the

    // Nashorn classes.

    private final ClassLoader commonLoader;

    // Is this a generator for the version of the class that can have overrides on the class level?

    private final boolean classOverride;

    // Binary name of the superClass

    private final String superClassName;

    // Binary name of the generated class.

    private final String generatedClassName;

    private final Set<String> usedFieldNames = new HashSet<>();

    private final Set<String> abstractMethodNames = new HashSet<>();

    private final String samName;

    private final Set<MethodInfo> finalMethods = new HashSet<>(EXCLUDED);

    private final Set<MethodInfo> methodInfos = new HashSet<>();

    private boolean autoConvertibleFromFunction = false;

    private final ClassWriter cw;

    /**

     * Creates a generator for the bytecode for the adapter for the specified superclass and interfaces.

     * @param superClass the superclass the adapter will extend.

     * @param interfaces the interfaces the adapter will implement.

     * @param commonLoader the class loader that can see all of superClass, interfaces, and Nashorn classes.

     * @param classOverride true to generate the bytecode for the adapter that has both class-level and instance-level

     * overrides, false to generate the bytecode for the adapter that only has instance-level overrides.

     * @throws AdaptationException if the adapter can not be generated for some reason.

     */

    JavaAdapterBytecodeGenerator(final Class<?> superClass, final List<Class<?>> interfaces,

            final ClassLoader commonLoader, final boolean classOverride) throws AdaptationException {

        assert superClass != null && !superClass.isInterface();

        assert interfaces != null;

        this.superClass = superClass;

        this.classOverride = classOverride;

        this.commonLoader = commonLoader;

        cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS) {

            @Override

            protected String getCommonSuperClass(final String type1, final String type2) {

                // We need to override ClassWriter.getCommonSuperClass to use this factory's commonLoader as a class

                // loader to find the common superclass of two types when needed.

                return JavaAdapterBytecodeGenerator.this.getCommonSuperClass(type1, type2);

            }

        };

        superClassName = Type.getInternalName(superClass);

        generatedClassName = getGeneratedClassName(superClass, interfaces);

        cw.visit(Opcodes.V1_7, ACC_PUBLIC | ACC_SUPER | ACC_FINAL, generatedClassName, null, superClassName, getInternalTypeNames(interfaces));

        generateGlobalFields();

        gatherMethods(superClass);

        gatherMethods(interfaces);

        samName = abstractMethodNames.size() == 1 ? abstractMethodNames.iterator().next() : null;

        generateHandleFields();

        if(classOverride) {

            generateClassInit();

        }

        generateConstructors();

        generateMethods();

        // }

        cw.visitEnd();

    }

    private void generateGlobalFields() {

        cw.visitField(ACC_PRIVATE | ACC_FINAL, GLOBAL_FIELD_NAME, SCRIPT_OBJECT_TYPE_DESCRIPTOR, null, null).visitEnd();

        usedFieldNames.add(GLOBAL_FIELD_NAME);

        if(classOverride) {

            cw.visitField(ACC_PRIVATE | ACC_FINAL | ACC_STATIC, STATIC_GLOBAL_FIELD_NAME, SCRIPT_OBJECT_TYPE_DESCRIPTOR, null, null).visitEnd();

            usedFieldNames.add(STATIC_GLOBAL_FIELD_NAME);

        }

    }

    JavaAdapterClassLoader createAdapterClassLoader() {

        return new JavaAdapterClassLoader(generatedClassName, cw.toByteArray());

    }

    boolean isAutoConvertibleFromFunction() {

        return autoConvertibleFromFunction;

    }

    private static String getGeneratedClassName(final Class<?> superType, final List<Class<?>> interfaces) {

        // The class we use to primarily name our adapter is either the superclass, or if it is Object (meaning we're

        // just implementing interfaces or extending Object), then the first implemented interface or Object.

        final Class<?> namingType = superType == Object.class ? (interfaces.isEmpty()? Object.class : interfaces.get(0)) : superType;

        final Package pkg = namingType.getPackage();

        final String namingTypeName = Type.getInternalName(namingType);

        final StringBuilder buf = new StringBuilder();

        if (namingTypeName.startsWith(JAVA_PACKAGE_PREFIX) || pkg == null || pkg.isSealed()) {

            // Can't define new classes in java.* packages

            buf.append(ADAPTER_PACKAGE_PREFIX).append(namingTypeName);

        } else {

            buf.append(namingTypeName).append(ADAPTER_CLASS_NAME_SUFFIX);

        }

        final Iterator<Class<?>> it = interfaces.iterator();

        if(superType == Object.class && it.hasNext()) {

            it.next(); // Skip first interface, it was used to primarily name the adapter

        }

        // Append interface names to the adapter name

        while(it.hasNext()) {

            buf.append("$$").append(it.next().getSimpleName());

        }

        return buf.toString().substring(0, Math.min(MAX_GENERATED_TYPE_NAME_LENGTH, buf.length()));

    }

    /**

     * Given a list of class objects, return an array with their binary names. Used to generate the array of interface

     * names to implement.

     * @param classes the classes

     * @return an array of names

     */

    private static String[] getInternalTypeNames(final List<Class<?>> classes) {

        final int interfaceCount = classes.size();

        final String[] interfaceNames = new String[interfaceCount];

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

            interfaceNames[i] = Type.getInternalName(classes.get(i));

        }

        return interfaceNames;

    }

    private void generateHandleFields() {

        for (final MethodInfo mi: methodInfos) {

            cw.visitField(ACC_PRIVATE | ACC_FINAL, mi.methodHandleInstanceFieldName, METHOD_HANDLE_TYPE_DESCRIPTOR, null, null).visitEnd();

            if(classOverride) {

                cw.visitField(ACC_PRIVATE | ACC_FINAL | ACC_STATIC, mi.methodHandleClassFieldName, METHOD_HANDLE_TYPE_DESCRIPTOR, null, null).visitEnd();

            }

        }

    }

    private void generateClassInit() {

        final InstructionAdapter mv = new InstructionAdapter(cw.visitMethod(ACC_STATIC, CLASS_INIT,

                Type.getMethodDescriptor(Type.VOID_TYPE), null, null));

        mv.invokestatic(SERVICES_CLASS_TYPE_NAME, "getClassOverrides", GET_CLASS_INITIALIZER_DESCRIPTOR);

        final Label initGlobal;

        if(samName != null) {

            // If the class is a SAM, allow having a ScriptFunction passed as class overrides

            final Label notAFunction = new Label();

            mv.dup();

            mv.instanceOf(SCRIPT_FUNCTION_TYPE);

            mv.ifeq(notAFunction);

            mv.checkcast(SCRIPT_FUNCTION_TYPE);

            // Assign MethodHandle fields through invoking getHandle() for a ScriptFunction, only assigning the SAM

            // method(s).

            for (final MethodInfo mi : methodInfos) {

                if(mi.getName().equals(samName)) {

                    mv.dup();

                    mv.aconst(Type.getMethodType(mi.type.toMethodDescriptorString()));

                    mv.invokestatic(SERVICES_CLASS_TYPE_NAME, "getHandle", GET_HANDLE_FUNCTION_DESCRIPTOR);

                } else {

                    mv.visitInsn(ACONST_NULL);

                }

                mv.putstatic(generatedClassName, mi.methodHandleClassFieldName, METHOD_HANDLE_TYPE_DESCRIPTOR);

            }

            initGlobal = new Label();

            mv.goTo(initGlobal);

            mv.visitLabel(notAFunction);

        } else {

            initGlobal = null;

        }

        // Assign MethodHandle fields through invoking getHandle() for a ScriptObject

        for (final MethodInfo mi : methodInfos) {

            mv.dup();

            mv.aconst(mi.getName());

            mv.aconst(Type.getMethodType(mi.type.toMethodDescriptorString()));

            mv.invokestatic(SERVICES_CLASS_TYPE_NAME, "getHandle", GET_HANDLE_OBJECT_DESCRIPTOR);

            mv.putstatic(generatedClassName, mi.methodHandleClassFieldName, METHOD_HANDLE_TYPE_DESCRIPTOR);

        }

        if(initGlobal != null) {

            mv.visitLabel(initGlobal);

        }

        // Assign "staticGlobal = Context.getGlobal()"

        invokeGetGlobalWithNullCheck(mv);

        mv.putstatic(generatedClassName, STATIC_GLOBAL_FIELD_NAME, SCRIPT_OBJECT_TYPE_DESCRIPTOR);

        endInitMethod(mv);

    }

    private static void invokeGetGlobalWithNullCheck(final InstructionAdapter mv) {

        invokeGetGlobal(mv);

        mv.dup();

        mv.invokevirtual(OBJECT_TYPE_NAME, "getClass", GET_CLASS_METHOD_DESCRIPTOR); // check against null Context

        mv.pop();

    }

    private void generateConstructors() throws AdaptationException {

        boolean gotCtor = false;

        for (final Constructor<?> ctor: superClass.getDeclaredConstructors()) {

            final int modifier = ctor.getModifiers();

            if((modifier & (Modifier.PUBLIC | Modifier.PROTECTED)) != 0 && !isCallerSensitive(ctor)) {

                generateConstructors(ctor);

                gotCtor = true;

            }

        }

        if(!gotCtor) {

            throw new AdaptationException(ERROR_NO_ACCESSIBLE_CONSTRUCTOR, superClass.getCanonicalName());

        }

    }

    private void generateConstructors(final Constructor<?> ctor) {

        if(classOverride) {

            // Generate a constructor that just delegates to ctor. This is used with class-level overrides, when we want

            // to create instances without further per-instance overrides.

            generateDelegatingConstructor(ctor);

        }

        // Generate a constructor that delegates to ctor, but takes an additional ScriptObject parameter at the

        // beginning of its parameter list.

        generateOverridingConstructor(ctor, false);

        if (samName != null) {

            if (!autoConvertibleFromFunction && ctor.getParameterTypes().length == 0) {

                // If the original type only has a single abstract method name, as well as a default ctor, then it can

                // be automatically converted from JS function.

                autoConvertibleFromFunction = true;

            }

            // If all our abstract methods have a single name, generate an additional constructor, one that takes a

            // ScriptFunction as its first parameter and assigns it as the implementation for all abstract methods.

            generateOverridingConstructor(ctor, true);

        }

    }

    private void generateDelegatingConstructor(final Constructor<?> ctor) {

        final Type originalCtorType = Type.getType(ctor);

        final Type[] argTypes = originalCtorType.getArgumentTypes();

        // All constructors must be public, even if in the superclass they were protected.

        final InstructionAdapter mv = new InstructionAdapter(cw.visitMethod(ACC_PUBLIC, INIT,

                Type.getMethodDescriptor(originalCtorType.getReturnType(), argTypes), null, null));

        mv.visitCode();

        // Invoke super constructor with the same arguments.

        mv.visitVarInsn(ALOAD, 0);

        int offset = 1; // First arg is at position 1, after this.

        for (Type argType: argTypes) {

            mv.load(offset, argType);

            offset += argType.getSize();

        }

        mv.invokespecial(superClassName, INIT, originalCtorType.getDescriptor());

        endInitMethod(mv);

    }

    /**

     * Generates a constructor for the adapter class. This constructor will take the same arguments as the supertype

     * constructor passed as the argument here, and delegate to it. However, it will take an additional argument of

     * either ScriptObject or ScriptFunction type (based on the value of the "fromFunction" parameter), and initialize

     * all the method handle fields of the adapter instance with functions from the script object (or the script

     * function itself, if that's what's passed). There is one method handle field in the adapter class for every method

     * that can be implemented or overridden; the name of every field is same as the name of the method, with a number

     * suffix that makes it unique in case of overloaded methods. The generated constructor will invoke

     * {@link #getHandle(ScriptFunction, MethodType, boolean)} or {@link #getHandle(Object, String, MethodType,

     * boolean)} to obtain the method handles; these methods make sure to add the necessary conversions and arity

     * adjustments so that the resulting method handles can be invoked from generated methods using {@code invokeExact}.

     * The constructor that takes a script function will only initialize the methods with the same name as the single

     * abstract method. The constructor will also store the Nashorn global that was current at the constructor

     * invocation time in a field named "global". The generated constructor will be public, regardless of whether the

     * supertype constructor was public or protected. The generated constructor will not be variable arity, even if the

     * supertype constructor was.

     * @param ctor the supertype constructor that is serving as the base for the generated constructor.

     * @param fromFunction true if we're generating a constructor that initializes SAM types from a single

     * ScriptFunction passed to it, false if we're generating a constructor that initializes an arbitrary type from a

     * ScriptObject passed to it.

     */

    private void generateOverridingConstructor(final Constructor<?> ctor, final boolean fromFunction) {

        final Type originalCtorType = Type.getType(ctor);

        final Type[] originalArgTypes = originalCtorType.getArgumentTypes();

        final int argLen = originalArgTypes.length;

        final Type[] newArgTypes = new Type[argLen + 1];

        // Insert ScriptFunction|Object as the last argument to the constructor

        final Type extraArgumentType = fromFunction ? SCRIPT_FUNCTION_TYPE : OBJECT_TYPE;

        newArgTypes[argLen] = extraArgumentType;

        System.arraycopy(originalArgTypes, 0, newArgTypes, 0, argLen);

        // All constructors must be public, even if in the superclass they were protected.

        // Existing super constructor <init>(this, args...) triggers generating <init>(this, scriptObj, args...).

        final InstructionAdapter mv = new InstructionAdapter(cw.visitMethod(ACC_PUBLIC, INIT,

                Type.getMethodDescriptor(originalCtorType.getReturnType(), newArgTypes), null, null));

        mv.visitCode();

        // First, invoke super constructor with original arguments. If the form of the constructor we're generating is

        // <init>(this, args..., scriptFn), then we're invoking super.<init>(this, args...).

        mv.visitVarInsn(ALOAD, 0);

        final Class<?>[] argTypes = ctor.getParameterTypes();

        int offset = 1; // First arg is at position 1, after this.

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

            final Type argType = Type.getType(argTypes[i]);

            mv.load(offset, argType);

            offset += argType.getSize();

        }

        mv.invokespecial(superClassName, INIT, originalCtorType.getDescriptor());

        // Get a descriptor to the appropriate "JavaAdapterFactory.getHandle" method.

        final String getHandleDescriptor = fromFunction ? GET_HANDLE_FUNCTION_DESCRIPTOR : GET_HANDLE_OBJECT_DESCRIPTOR;

        // Assign MethodHandle fields through invoking getHandle()

        for (final MethodInfo mi : methodInfos) {

            mv.visitVarInsn(ALOAD, 0);

            if (fromFunction && !mi.getName().equals(samName)) {

                // Constructors initializing from a ScriptFunction only initialize methods with the SAM name.

                // NOTE: if there's a concrete overloaded method sharing the SAM name, it'll be overriden too. This

                // is a deliberate design choice. All other method handles are initialized to null.

                mv.visitInsn(ACONST_NULL);

            } else {

                mv.visitVarInsn(ALOAD, offset);

                if(!fromFunction) {

                    mv.aconst(mi.getName());

                }

                mv.aconst(Type.getMethodType(mi.type.toMethodDescriptorString()));

                mv.invokestatic(SERVICES_CLASS_TYPE_NAME, "getHandle", getHandleDescriptor);

            }

            mv.putfield(generatedClassName, mi.methodHandleInstanceFieldName, METHOD_HANDLE_TYPE_DESCRIPTOR);

        }

        // Assign "this.global = Context.getGlobal()"

        mv.visitVarInsn(ALOAD, 0);

        invokeGetGlobalWithNullCheck(mv);

        mv.putfield(generatedClassName, GLOBAL_FIELD_NAME, SCRIPT_OBJECT_TYPE_DESCRIPTOR);

        endInitMethod(mv);

    }

    private static void endInitMethod(final InstructionAdapter mv) {

        mv.visitInsn(RETURN);

        mv.visitMaxs(0, 0);

        mv.visitEnd();

    }

    private static void invokeGetGlobal(final InstructionAdapter mv) {