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  * 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

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 package java.lang.invoke;

 import java.lang.reflect.*;

 import java.util.List;

 import java.util.ArrayList;

 import java.util.Arrays;

 import sun.invoke.util.ValueConversions;

 import sun.invoke.util.VerifyAccess;

 import sun.invoke.util.Wrapper;

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

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

 import java.util.concurrent.ConcurrentHashMap;

 /**

  * This class consists exclusively of static methods that operate on or return

  * method handles. They fall into several categories:

  * <ul>

  * <li>Lookup methods which help create method handles for methods and fields.

  * <li>Combinator methods, which combine or transform pre-existing method handles into new ones.

  * <li>Other factory methods to create method handles that emulate other common JVM operations or control flow patterns.

  * </ul>

  * <p>

  * @author John Rose, JSR 292 EG

  * @since 1.7

  */

 public class MethodHandles {

     private MethodHandles() { }  // do not instantiate

     private static final MemberName.Factory IMPL_NAMES = MemberName.getFactory();

     static { MethodHandleImpl.initStatics(); }

     // See IMPL_LOOKUP below.

     //// Method handle creation from ordinary methods.

     /**

      * Returns a {@link Lookup lookup object} with

      * full capabilities to emulate all supported bytecode behaviors of the caller.

      * These capabilities include <a href="MethodHandles.Lookup.html#privacc">private access</a> to the caller.

      * Factory methods on the lookup object can create

      * <a href="MethodHandleInfo.html#directmh">direct method handles</a>

      * for any member that the caller has access to via bytecodes,

      * including protected and private fields and methods.

      * This lookup object is a <em>capability</em> which may be delegated to trusted agents.

      * Do not store it in place where untrusted code can access it.

      * <p>

      * This method is caller sensitive, which means that it may return different

      * values to different callers.

      * <p>

      * For any given caller class {@code C}, the lookup object returned by this call

      * has equivalent capabilities to any lookup object

      * supplied by the JVM to the bootstrap method of an

      * <a href="package-summary.html#indyinsn">invokedynamic instruction</a>

      * executing in the same caller class {@code C}.

      * @return a lookup object for the caller of this method, with private access

      */

 //    @CallerSensitive

     public static Lookup lookup() {

         throw new IllegalStateException("Implement me!");

 //        return new Lookup(Reflection.getCallerClass());

     }

     /**

      * Returns a {@link Lookup lookup object} which is trusted minimally.

      * It can only be used to create method handles to

      * publicly accessible fields and methods.

      * <p>

      * As a matter of pure convention, the {@linkplain Lookup#lookupClass lookup class}

      * of this lookup object will be {@link java.lang.Object}.

      *

      * <p style="font-size:smaller;">

      * <em>Discussion:</em>

      * The lookup class can be changed to any other class {@code C} using an expression of the form

      * {@link Lookup#in publicLookup().in(C.class)}.

      * Since all classes have equal access to public names,

      * such a change would confer no new access rights.

      * A public lookup object is always subject to

      * <a href="MethodHandles.Lookup.html#secmgr">security manager checks</a>.

      * Also, it cannot access

      * <a href="MethodHandles.Lookup.html#callsens">caller sensitive methods</a>.

      * @return a lookup object which is trusted minimally

      */

     public static Lookup publicLookup() {

         return Lookup.PUBLIC_LOOKUP;

     }

     /**

      * Performs an unchecked "crack" of a

      * <a href="MethodHandleInfo.html#directmh">direct method handle</a>.

      * The result is as if the user had obtained a lookup object capable enough

      * to crack the target method handle, called

      * {@link java.lang.invoke.MethodHandles.Lookup#revealDirect Lookup.revealDirect}

      * on the target to obtain its symbolic reference, and then called

      * {@link java.lang.invoke.MethodHandleInfo#reflectAs MethodHandleInfo.reflectAs}

      * to resolve the symbolic reference to a member.

      * <p>

      * If there is a security manager, its {@code checkPermission} method

      * is called with a {@code ReflectPermission("suppressAccessChecks")} permission.

      * @param <T> the desired type of the result, either {@link Member} or a subtype

      * @param target a direct method handle to crack into symbolic reference components

      * @param expected a class object representing the desired result type {@code T}

      * @return a reference to the method, constructor, or field object

      * @exception SecurityException if the caller is not privileged to call {@code setAccessible}

      * @exception NullPointerException if either argument is {@code null}

      * @exception IllegalArgumentException if the target is not a direct method handle

      * @exception ClassCastException if the member is not of the expected type

      * @since 1.8

      */

     public static <T extends Member> T

     reflectAs(Class<T> expected, MethodHandle target) {

 //        SecurityManager smgr = System.getSecurityManager();

 //        if (smgr != null)  smgr.checkPermission(ACCESS_PERMISSION);

         Lookup lookup = Lookup.IMPL_LOOKUP;  // use maximally privileged lookup

         return lookup.revealDirect(target).reflectAs(expected, lookup);

     }

     // Copied from AccessibleObject, as used by Method.setAccessible, etc.:

 //    static final private java.security.Permission ACCESS_PERMISSION =

 //        new ReflectPermission("suppressAccessChecks");

     /**

      * A <em>lookup object</em> is a factory for creating method handles,

      * when the creation requires access checking.

      * Method handles do not perform

      * access checks when they are called, but rather when they are created.

      * Therefore, method handle access

      * restrictions must be enforced when a method handle is created.

      * The caller class against which those restrictions are enforced

      * is known as the {@linkplain #lookupClass lookup class}.

      * <p>

      * A lookup class which needs to create method handles will call

      * {@link MethodHandles#lookup MethodHandles.lookup} to create a factory for itself.

      * When the {@code Lookup} factory object is created, the identity of the lookup class is

      * determined, and securely stored in the {@code Lookup} object.

      * The lookup class (or its delegates) may then use factory methods

      * on the {@code Lookup} object to create method handles for access-checked members.

      * This includes all methods, constructors, and fields which are allowed to the lookup class,

      * even private ones.

      *

      * <h1><a name="lookups"></a>Lookup Factory Methods</h1>

      * The factory methods on a {@code Lookup} object correspond to all major

      * use cases for methods, constructors, and fields.

      * Each method handle created by a factory method is the functional

      * equivalent of a particular <em>bytecode behavior</em>.

      * (Bytecode behaviors are described in section 5.4.3.5 of the Java Virtual Machine Specification.)

      * Here is a summary of the correspondence between these factory methods and

      * the behavior the resulting method handles:

      * <table border=1 cellpadding=5 summary="lookup method behaviors">

      * <tr>

      *     <th><a name="equiv"></a>lookup expression</th>

      *     <th>member</th>

      *     <th>bytecode behavior</th>

      * </tr>

      * <tr>

      *     <td>{@link java.lang.invoke.MethodHandles.Lookup#findGetter lookup.findGetter(C.class,"f",FT.class)}</td>

      *     <td>{@code FT f;}</td><td>{@code (T) this.f;}</td>

      * </tr>

      * <tr>

      *     <td>{@link java.lang.invoke.MethodHandles.Lookup#findStaticGetter lookup.findStaticGetter(C.class,"f",FT.class)}</td>

      *     <td>{@code static}<br>{@code FT f;}</td><td>{@code (T) C.f;}</td>

      * </tr>

      * <tr>

      *     <td>{@link java.lang.invoke.MethodHandles.Lookup#findSetter lookup.findSetter(C.class,"f",FT.class)}</td>

      *     <td>{@code FT f;}</td><td>{@code this.f = x;}</td>

      * </tr>

      * <tr>

      *     <td>{@link java.lang.invoke.MethodHandles.Lookup#findStaticSetter lookup.findStaticSetter(C.class,"f",FT.class)}</td>

      *     <td>{@code static}<br>{@code FT f;}</td><td>{@code C.f = arg;}</td>

      * </tr>

      * <tr>

      *     <td>{@link java.lang.invoke.MethodHandles.Lookup#findVirtual lookup.findVirtual(C.class,"m",MT)}</td>

      *     <td>{@code T m(A*);}</td><td>{@code (T) this.m(arg*);}</td>

      * </tr>

      * <tr>

      *     <td>{@link java.lang.invoke.MethodHandles.Lookup#findStatic lookup.findStatic(C.class,"m",MT)}</td>

      *     <td>{@code static}<br>{@code T m(A*);}</td><td>{@code (T) C.m(arg*);}</td>

      * </tr>

      * <tr>

      *     <td>{@link java.lang.invoke.MethodHandles.Lookup#findSpecial lookup.findSpecial(C.class,"m",MT,this.class)}</td>

      *     <td>{@code T m(A*);}</td><td>{@code (T) super.m(arg*);}</td>

      * </tr>

      * <tr>

      *     <td>{@link java.lang.invoke.MethodHandles.Lookup#findConstructor lookup.findConstructor(C.class,MT)}</td>

      *     <td>{@code C(A*);}</td><td>{@code new C(arg*);}</td>

      * </tr>

      * <tr>

      *     <td>{@link java.lang.invoke.MethodHandles.Lookup#unreflectGetter lookup.unreflectGetter(aField)}</td>

      *     <td>({@code static})?<br>{@code FT f;}</td><td>{@code (FT) aField.get(thisOrNull);}</td>

      * </tr>

      * <tr>

      *     <td>{@link java.lang.invoke.MethodHandles.Lookup#unreflectSetter lookup.unreflectSetter(aField)}</td>

      *     <td>({@code static})?<br>{@code FT f;}</td><td>{@code aField.set(thisOrNull, arg);}</td>

      * </tr>

      * <tr>

      *     <td>{@link java.lang.invoke.MethodHandles.Lookup#unreflect lookup.unreflect(aMethod)}</td>

      *     <td>({@code static})?<br>{@code T m(A*);}</td><td>{@code (T) aMethod.invoke(thisOrNull, arg*);}</td>

      * </tr>

      * <tr>

      *     <td>{@link java.lang.invoke.MethodHandles.Lookup#unreflectConstructor lookup.unreflectConstructor(aConstructor)}</td>

      *     <td>{@code C(A*);}</td><td>{@code (C) aConstructor.newInstance(arg*);}</td>

      * </tr>

      * <tr>

      *     <td>{@link java.lang.invoke.MethodHandles.Lookup#unreflect lookup.unreflect(aMethod)}</td>

      *     <td>({@code static})?<br>{@code T m(A*);}</td><td>{@code (T) aMethod.invoke(thisOrNull, arg*);}</td>

      * </tr>

      * </table>

      *

      * Here, the type {@code C} is the class or interface being searched for a member,

      * documented as a parameter named {@code refc} in the lookup methods.

      * The method type {@code MT} is composed from the return type {@code T}

      * and the sequence of argument types {@code A*}.

      * The constructor also has a sequence of argument types {@code A*} and

      * is deemed to return the newly-created object of type {@code C}.

      * Both {@code MT} and the field type {@code FT} are documented as a parameter named {@code type}.

      * The formal parameter {@code this} stands for the self-reference of type {@code C};

      * if it is present, it is always the leading argument to the method handle invocation.

      * (In the case of some {@code protected} members, {@code this} may be

      * restricted in type to the lookup class; see below.)

      * The name {@code arg} stands for all the other method handle arguments.

      * In the code examples for the Core Reflection API, the name {@code thisOrNull}

      * stands for a null reference if the accessed method or field is static,

      * and {@code this} otherwise.

      * The names {@code aMethod}, {@code aField}, and {@code aConstructor} stand

      * for reflective objects corresponding to the given members.

      * <p>

      * In cases where the given member is of variable arity (i.e., a method or constructor)

      * the returned method handle will also be of {@linkplain MethodHandle#asVarargsCollector variable arity}.

      * In all other cases, the returned method handle will be of fixed arity.

      * <p style="font-size:smaller;">

      * <em>Discussion:</em>

      * The equivalence between looked-up method handles and underlying

      * class members and bytecode behaviors

      * can break down in a few ways:

      * <ul style="font-size:smaller;">

      * <li>If {@code C} is not symbolically accessible from the lookup class's loader,

      * the lookup can still succeed, even when there is no equivalent

      * Java expression or bytecoded constant.

      * <li>Likewise, if {@code T} or {@code MT}

      * is not symbolically accessible from the lookup class's loader,

      * the lookup can still succeed.

      * For example, lookups for {@code MethodHandle.invokeExact} and

      * {@code MethodHandle.invoke} will always succeed, regardless of requested type.

      * <li>If there is a security manager installed, it can forbid the lookup

      * on various grounds (<a href="MethodHandles.Lookup.html#secmgr">see below</a>).

      * By contrast, the {@code ldc} instruction on a {@code CONSTANT_MethodHandle}

      * constant is not subject to security manager checks.

      * <li>If the looked-up method has a

      * <a href="MethodHandle.html#maxarity">very large arity</a>,

      * the method handle creation may fail, due to the method handle

      * type having too many parameters.

      * </ul>

      *

      * <h1><a name="access"></a>Access checking</h1>

      * Access checks are applied in the factory methods of {@code Lookup},

      * when a method handle is created.

      * This is a key difference from the Core Reflection API, since

      * {@link java.lang.reflect.Method#invoke java.lang.reflect.Method.invoke}

      * performs access checking against every caller, on every call.

      * <p>

      * All access checks start from a {@code Lookup} object, which

      * compares its recorded lookup class against all requests to

      * create method handles.

      * A single {@code Lookup} object can be used to create any number

      * of access-checked method handles, all checked against a single

      * lookup class.

      * <p>

      * A {@code Lookup} object can be shared with other trusted code,

      * such as a metaobject protocol.

      * A shared {@code Lookup} object delegates the capability

      * to create method handles on private members of the lookup class.

      * Even if privileged code uses the {@code Lookup} object,

      * the access checking is confined to the privileges of the

      * original lookup class.

      * <p>

      * A lookup can fail, because

      * the containing class is not accessible to the lookup class, or

      * because the desired class member is missing, or because the

      * desired class member is not accessible to the lookup class, or

      * because the lookup object is not trusted enough to access the member.

      * In any of these cases, a {@code ReflectiveOperationException} will be

      * thrown from the attempted lookup.  The exact class will be one of

      * the following:

      * <ul>

      * <li>NoSuchMethodException &mdash; if a method is requested but does not exist

      * <li>NoSuchFieldException &mdash; if a field is requested but does not exist

      * <li>IllegalAccessException &mdash; if the member exists but an access check fails

      * </ul>

      * <p>

      * In general, the conditions under which a method handle may be

      * looked up for a method {@code M} are no more restrictive than the conditions

      * under which the lookup class could have compiled, verified, and resolved a call to {@code M}.

      * Where the JVM would raise exceptions like {@code NoSuchMethodError},

      * a method handle lookup will generally raise a corresponding

      * checked exception, such as {@code NoSuchMethodException}.

      * And the effect of invoking the method handle resulting from the lookup

      * is <a href="MethodHandles.Lookup.html#equiv">exactly equivalent</a>

      * to executing the compiled, verified, and resolved call to {@code M}.

      * The same point is true of fields and constructors.

      * <p style="font-size:smaller;">

      * <em>Discussion:</em>

      * Access checks only apply to named and reflected methods,

      * constructors, and fields.

      * Other method handle creation methods, such as

      * {@link MethodHandle#asType MethodHandle.asType},

      * do not require any access checks, and are used

      * independently of any {@code Lookup} object.

      * <p>

      * If the desired member is {@code protected}, the usual JVM rules apply,

      * including the requirement that the lookup class must be either be in the

      * same package as the desired member, or must inherit that member.

      * (See the Java Virtual Machine Specification, sections 4.9.2, 5.4.3.5, and 6.4.)

      * In addition, if the desired member is a non-static field or method

      * in a different package, the resulting method handle may only be applied

      * to objects of the lookup class or one of its subclasses.

      * This requirement is enforced by narrowing the type of the leading

      * {@code this} parameter from {@code C}

      * (which will necessarily be a superclass of the lookup class)

      * to the lookup class itself.

      * <p>

      * The JVM imposes a similar requirement on {@code invokespecial} instruction,

      * that the receiver argument must match both the resolved method <em>and</em>

      * the current class.  Again, this requirement is enforced by narrowing the

      * type of the leading parameter to the resulting method handle.

      * (See the Java Virtual Machine Specification, section 4.10.1.9.)

      * <p>

      * The JVM represents constructors and static initializer blocks as internal methods

      * with special names ({@code "<init>"} and {@code "<clinit>"}).

      * The internal syntax of invocation instructions allows them to refer to such internal

      * methods as if they were normal methods, but the JVM bytecode verifier rejects them.

      * A lookup of such an internal method will produce a {@code NoSuchMethodException}.

      * <p>

      * In some cases, access between nested classes is obtained by the Java compiler by creating

      * an wrapper method to access a private method of another class

      * in the same top-level declaration.

      * For example, a nested class {@code C.D}

      * can access private members within other related classes such as

      * {@code C}, {@code C.D.E}, or {@code C.B},

      * but the Java compiler may need to generate wrapper methods in

      * those related classes.  In such cases, a {@code Lookup} object on

      * {@code C.E} would be unable to those private members.

      * A workaround for this limitation is the {@link Lookup#in Lookup.in} method,

      * which can transform a lookup on {@code C.E} into one on any of those other

      * classes, without special elevation of privilege.

      * <p>

      * The accesses permitted to a given lookup object may be limited,

      * according to its set of {@link #lookupModes lookupModes},

      * to a subset of members normally accessible to the lookup class.

      * For example, the {@link MethodHandles#publicLookup publicLookup}

      * method produces a lookup object which is only allowed to access

      * public members in public classes.

      * The caller sensitive method {@link MethodHandles#lookup lookup}

      * produces a lookup object with full capabilities relative to

      * its caller class, to emulate all supported bytecode behaviors.

      * Also, the {@link Lookup#in Lookup.in} method may produce a lookup object

      * with fewer access modes than the original lookup object.

      *

      * <p style="font-size:smaller;">

      * <a name="privacc"></a>

      * <em>Discussion of private access:</em>

      * We say that a lookup has <em>private access</em>

      * if its {@linkplain #lookupModes lookup modes}

      * include the possibility of accessing {@code private} members.

      * As documented in the relevant methods elsewhere,

      * only lookups with private access possess the following capabilities:

      * <ul style="font-size:smaller;">

      * <li>access private fields, methods, and constructors of the lookup class

      * <li>create method handles which invoke <a href="MethodHandles.Lookup.html#callsens">caller sensitive</a> methods,

      *     such as {@code Class.forName}

      * <li>create method handles which {@link Lookup#findSpecial emulate invokespecial} instructions

      * <li>avoid <a href="MethodHandles.Lookup.html#secmgr">package access checks</a>

      *     for classes accessible to the lookup class

      * <li>create {@link Lookup#in delegated lookup objects} which have private access to other classes

      *     within the same package member

      * </ul>

      * <p style="font-size:smaller;">

      * Each of these permissions is a consequence of the fact that a lookup object

      * with private access can be securely traced back to an originating class,

      * whose <a href="MethodHandles.Lookup.html#equiv">bytecode behaviors</a> and Java language access permissions

      * can be reliably determined and emulated by method handles.

      *

      * <h1><a name="secmgr"></a>Security manager interactions</h1>

      * Although bytecode instructions can only refer to classes in

      * a related class loader, this API can search for methods in any

      * class, as long as a reference to its {@code Class} object is

      * available.  Such cross-loader references are also possible with the

      * Core Reflection API, and are impossible to bytecode instructions

      * such as {@code invokestatic} or {@code getfield}.

      * There is a {@linkplain java.lang.SecurityManager security manager API}

      * to allow applications to check such cross-loader references.

      * These checks apply to both the {@code MethodHandles.Lookup} API

      * and the Core Reflection API

      * (as found on {@link java.lang.Class Class}).

      * <p>

      * If a security manager is present, member lookups are subject to

      * additional checks.

      * From one to three calls are made to the security manager.

      * Any of these calls can refuse access by throwing a

      * {@link java.lang.SecurityException SecurityException}.

      * Define {@code smgr} as the security manager,

      * {@code lookc} as the lookup class of the current lookup object,

      * {@code refc} as the containing class in which the member

      * is being sought, and {@code defc} as the class in which the

      * member is actually defined.

      * The value {@code lookc} is defined as <em>not present</em>

      * if the current lookup object does not have

      * <a href="MethodHandles.Lookup.html#privacc">private access</a>.

      * The calls are made according to the following rules:

      * <ul>

      * <li><b>Step 1:</b>

      *     If {@code lookc} is not present, or if its class loader is not

      *     the same as or an ancestor of the class loader of {@code refc},

      *     then {@link SecurityManager#checkPackageAccess

      *     smgr.checkPackageAccess(refcPkg)} is called,

      *     where {@code refcPkg} is the package of {@code refc}.

      * <li><b>Step 2:</b>

      *     If the retrieved member is not public and

      *     {@code lookc} is not present, then

      *     {@link SecurityManager#checkPermission smgr.checkPermission}

      *     with {@code RuntimePermission("accessDeclaredMembers")} is called.

      * <li><b>Step 3:</b>

      *     If the retrieved member is not public,

      *     and if {@code lookc} is not present,

      *     and if {@code defc} and {@code refc} are different,

      *     then {@link SecurityManager#checkPackageAccess

      *     smgr.checkPackageAccess(defcPkg)} is called,

      *     where {@code defcPkg} is the package of {@code defc}.

      * </ul>

      * Security checks are performed after other access checks have passed.

      * Therefore, the above rules presuppose a member that is public,

      * or else that is being accessed from a lookup class that has

      * rights to access the member.

      *

      * <h1><a name="callsens"></a>Caller sensitive methods</h1>

      * A small number of Java methods have a special property called caller sensitivity.

      * A <em>caller-sensitive</em> method can behave differently depending on the

      * identity of its immediate caller.

      * <p>

      * If a method handle for a caller-sensitive method is requested,

      * the general rules for <a href="MethodHandles.Lookup.html#equiv">bytecode behaviors</a> apply,

      * but they take account of the lookup class in a special way.

      * The resulting method handle behaves as if it were called

      * from an instruction contained in the lookup class,

      * so that the caller-sensitive method detects the lookup class.

      * (By contrast, the invoker of the method handle is disregarded.)

      * Thus, in the case of caller-sensitive methods,

      * different lookup classes may give rise to

      * differently behaving method handles.

      * <p>

      * In cases where the lookup object is

      * {@link MethodHandles#publicLookup() publicLookup()},

      * or some other lookup object without

      * <a href="MethodHandles.Lookup.html#privacc">private access</a>,

      * the lookup class is disregarded.

      * In such cases, no caller-sensitive method handle can be created,

      * access is forbidden, and the lookup fails with an

      * {@code IllegalAccessException}.

      * <p style="font-size:smaller;">

      * <em>Discussion:</em>

      * For example, the caller-sensitive method

      * {@link java.lang.Class#forName(String) Class.forName(x)}

      * can return varying classes or throw varying exceptions,

      * depending on the class loader of the class that calls it.

      * A public lookup of {@code Class.forName} will fail, because

      * there is no reasonable way to determine its bytecode behavior.

      * <p style="font-size:smaller;">

      * If an application caches method handles for broad sharing,

      * it should use {@code publicLookup()} to create them.

      * If there is a lookup of {@code Class.forName}, it will fail,

      * and the application must take appropriate action in that case.

      * It may be that a later lookup, perhaps during the invocation of a

      * bootstrap method, can incorporate the specific identity

      * of the caller, making the method accessible.

      * <p style="font-size:smaller;">

      * The function {@code MethodHandles.lookup} is caller sensitive

      * so that there can be a secure foundation for lookups.

      * Nearly all other methods in the JSR 292 API rely on lookup

      * objects to check access requests.

      */

     public static final

     class Lookup {

         /** The class on behalf of whom the lookup is being performed. */

         private final Class<?> lookupClass;

         /** The allowed sorts of members which may be looked up (PUBLIC, etc.). */

         private final int allowedModes;

         /** A single-bit mask representing {@code public} access,

          *  which may contribute to the result of {@link #lookupModes lookupModes}.

          *  The value, {@code 0x01}, happens to be the same as the value of the

          *  {@code public} {@linkplain java.lang.reflect.Modifier#PUBLIC modifier bit}.

          */

         public static final int PUBLIC = Modifier.PUBLIC;

         /** A single-bit mask representing {@code private} access,

          *  which may contribute to the result of {@link #lookupModes lookupModes}.

          *  The value, {@code 0x02}, happens to be the same as the value of the

          *  {@code private} {@linkplain java.lang.reflect.Modifier#PRIVATE modifier bit}.

          */

         public static final int PRIVATE = Modifier.PRIVATE;

         /** A single-bit mask representing {@code protected} access,

          *  which may contribute to the result of {@link #lookupModes lookupModes}.

          *  The value, {@code 0x04}, happens to be the same as the value of the

          *  {@code protected} {@linkplain java.lang.reflect.Modifier#PROTECTED modifier bit}.

          */

         public static final int PROTECTED = Modifier.PROTECTED;

         /** A single-bit mask representing {@code package} access (default access),

          *  which may contribute to the result of {@link #lookupModes lookupModes}.

          *  The value is {@code 0x08}, which does not correspond meaningfully to

          *  any particular {@linkplain java.lang.reflect.Modifier modifier bit}.

          */

         public static final int PACKAGE = Modifier.STATIC;

         private static final int ALL_MODES = (PUBLIC | PRIVATE | PROTECTED | PACKAGE);

         private static final int TRUSTED   = -1;

         private static int fixmods(int mods) {

             mods &= (ALL_MODES - PACKAGE);

             return (mods != 0) ? mods : PACKAGE;

         }

         /** Tells which class is performing the lookup.  It is this class against

          *  which checks are performed for visibility and access permissions.

          *  <p>

          *  The class implies a maximum level of access permission,

          *  but the permissions may be additionally limited by the bitmask

          *  {@link #lookupModes lookupModes}, which controls whether non-public members

          *  can be accessed.

          *  @return the lookup class, on behalf of which this lookup object finds members

          */

         public Class<?> lookupClass() {

             return lookupClass;

         }

         // This is just for calling out to MethodHandleImpl.

         private Class<?> lookupClassOrNull() {

             return (allowedModes == TRUSTED) ? null : lookupClass;

         }

         /** Tells which access-protection classes of members this lookup object can produce.

          *  The result is a bit-mask of the bits

          *  {@linkplain #PUBLIC PUBLIC (0x01)},

          *  {@linkplain #PRIVATE PRIVATE (0x02)},

          *  {@linkplain #PROTECTED PROTECTED (0x04)},

          *  and {@linkplain #PACKAGE PACKAGE (0x08)}.

          *  <p>

          *  A freshly-created lookup object

          *  on the {@linkplain java.lang.invoke.MethodHandles#lookup() caller's class}

          *  has all possible bits set, since the caller class can access all its own members.

          *  A lookup object on a new lookup class

          *  {@linkplain java.lang.invoke.MethodHandles.Lookup#in created from a previous lookup object}

          *  may have some mode bits set to zero.

          *  The purpose of this is to restrict access via the new lookup object,

          *  so that it can access only names which can be reached by the original

          *  lookup object, and also by the new lookup class.

          *  @return the lookup modes, which limit the kinds of access performed by this lookup object

          */

         public int lookupModes() {

             return allowedModes & ALL_MODES;

         }

         /** Embody the current class (the lookupClass) as a lookup class

          * for method handle creation.

          * Must be called by from a method in this package,

          * which in turn is called by a method not in this package.

          */

         Lookup(Class<?> lookupClass) {

             this(lookupClass, ALL_MODES);

             // make sure we haven't accidentally picked up a privileged class:

             checkUnprivilegedlookupClass(lookupClass, ALL_MODES);

         }

         private Lookup(Class<?> lookupClass, int allowedModes) {

             this.lookupClass = lookupClass;

             this.allowedModes = allowedModes;

         }

         /**

          * Creates a lookup on the specified new lookup class.

          * The resulting object will report the specified

          * class as its own {@link #lookupClass lookupClass}.

          * <p>

          * However, the resulting {@code Lookup} object is guaranteed

          * to have no more access capabilities than the original.

          * In particular, access capabilities can be lost as follows:<ul>

          * <li>If the new lookup class differs from the old one,

          * protected members will not be accessible by virtue of inheritance.

          * (Protected members may continue to be accessible because of package sharing.)

          * <li>If the new lookup class is in a different package

          * than the old one, protected and default (package) members will not be accessible.

          * <li>If the new lookup class is not within the same package member

          * as the old one, private members will not be accessible.

          * <li>If the new lookup class is not accessible to the old lookup class,

          * then no members, not even public members, will be accessible.

          * (In all other cases, public members will continue to be accessible.)

          * </ul>

          *

          * @param requestedLookupClass the desired lookup class for the new lookup object

          * @return a lookup object which reports the desired lookup class

          * @throws NullPointerException if the argument is null

          */

         public Lookup in(Class<?> requestedLookupClass) {

             requestedLookupClass.getClass();  // null check

             if (allowedModes == TRUSTED)  // IMPL_LOOKUP can make any lookup at all

                 return new Lookup(requestedLookupClass, ALL_MODES);

             if (requestedLookupClass == this.lookupClass)

                 return this;  // keep same capabilities

             int newModes = (allowedModes & (ALL_MODES & ~PROTECTED));

             if ((newModes & PACKAGE) != 0

                 && !VerifyAccess.isSamePackage(this.lookupClass, requestedLookupClass)) {

                 newModes &= ~(PACKAGE|PRIVATE);

             }

             // Allow nestmate lookups to be created without special privilege:

             if ((newModes & PRIVATE) != 0

                 && !VerifyAccess.isSamePackageMember(this.lookupClass, requestedLookupClass)) {

                 newModes &= ~PRIVATE;

             }

             if ((newModes & PUBLIC) != 0

                 && !VerifyAccess.isClassAccessible(requestedLookupClass, this.lookupClass, allowedModes)) {

                 // The requested class it not accessible from the lookup class.

                 // No permissions.

                 newModes = 0;

             }

             checkUnprivilegedlookupClass(requestedLookupClass, newModes);

             return new Lookup(requestedLookupClass, newModes);

         }

         // Make sure outer class is initialized first.

         static { IMPL_NAMES.getClass(); }

         /** Version of lookup which is trusted minimally.

          *  It can only be used to create method handles to

          *  publicly accessible members.

          */

         static final Lookup PUBLIC_LOOKUP = new Lookup(Object.class, PUBLIC);

         /** Package-private version of lookup which is trusted. */

         static final Lookup IMPL_LOOKUP = new Lookup(Object.class, TRUSTED);

         private static void checkUnprivilegedlookupClass(Class<?> lookupClass, int allowedModes) {

             String name = lookupClass.getName();

             if (name.startsWith("java.lang.invoke."))

                 throw newIllegalArgumentException("illegal lookupClass: "+lookupClass);

             // For caller-sensitive MethodHandles.lookup()

             // disallow lookup more restricted packages

             if (allowedModes == ALL_MODES && lookupClass.getClassLoader() == null) {

                 if (name.startsWith("java.") ||

                         (name.startsWith("sun.") && !name.startsWith("sun.invoke."))) {

                     throw newIllegalArgumentException("illegal lookupClass: " + lookupClass);

                 }

             }

         }

         /**

          * Displays the name of the class from which lookups are to be made.

          * (The name is the one reported by {@link java.lang.Class#getName() Class.getName}.)

          * If there are restrictions on the access permitted to this lookup,

          * this is indicated by adding a suffix to the class name, consisting

          * of a slash and a keyword.  The keyword represents the strongest

          * allowed access, and is chosen as follows:

          * <ul>

          * <li>If no access is allowed, the suffix is "/noaccess".

          * <li>If only public access is allowed, the suffix is "/public".

          * <li>If only public and package access are allowed, the suffix is "/package".

          * <li>If only public, package, and private access are allowed, the suffix is "/private".

          * </ul>

          * If none of the above cases apply, it is the case that full

          * access (public, package, private, and protected) is allowed.

          * In this case, no suffix is added.

          * This is true only of an object obtained originally from

          * {@link java.lang.invoke.MethodHandles#lookup MethodHandles.lookup}.

          * Objects created by {@link java.lang.invoke.MethodHandles.Lookup#in Lookup.in}

          * always have restricted access, and will display a suffix.

          * <p>

          * (It may seem strange that protected access should be

          * stronger than private access.  Viewed independently from

          * package access, protected access is the first to be lost,

          * because it requires a direct subclass relationship between

          * caller and callee.)

          * @see #in

          */

         @Override

         public String toString() {

             String cname = lookupClass.getName();

             switch (allowedModes) {

             case 0:  // no privileges

                 return cname + "/noaccess";

             case PUBLIC:

                 return cname + "/public";

             case PUBLIC|PACKAGE:

                 return cname + "/package";

             case ALL_MODES & ~PROTECTED:

                 return cname + "/private";

             case ALL_MODES:

                 return cname;

             case TRUSTED:

                 return "/trusted";  // internal only; not exported

             default:  // Should not happen, but it's a bitfield...

                 cname = cname + "/" + Integer.toHexString(allowedModes);

                 assert(false) : cname;

                 return cname;

             }

         }

         /**

          * Produces a method handle for a static method.

          * The type of the method handle will be that of the method.

          * (Since static methods do not take receivers, there is no

          * additional receiver argument inserted into the method handle type,

          * as there would be with {@link #findVirtual findVirtual} or {@link #findSpecial findSpecial}.)

          * The method and all its argument types must be accessible to the lookup object.

          * <p>

          * The returned method handle will have

          * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if

          * the method's variable arity modifier bit ({@code 0x0080}) is set.

          * <p>

          * If the returned method handle is invoked, the method's class will

          * be initialized, if it has not already been initialized.

          * <p><b>Example:</b>

          * <blockquote><pre>{@code

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

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

 ...

 MethodHandle MH_asList = publicLookup().findStatic(Arrays.class,

   "asList", methodType(List.class, Object[].class));

 assertEquals("[x, y]", MH_asList.invoke("x", "y").toString());

          * }</pre></blockquote>

          * @param refc the class from which the method is accessed

          * @param name the name of the method

          * @param type the type of the method

          * @return the desired method handle

          * @throws NoSuchMethodException if the method does not exist

          * @throws IllegalAccessException if access checking fails,

          *                                or if the method is not {@code static},

          *                                or if the method's variable arity modifier bit

          *                                is set and {@code asVarargsCollector} fails

          * @exception SecurityException if a security manager is present and it

          *                              <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>

          * @throws NullPointerException if any argument is null

          */

         public

         MethodHandle findStatic(Class<?> refc, String name, MethodType type) throws NoSuchMethodException, IllegalAccessException {

             MemberName method = resolveOrFail(REF_invokeStatic, refc, name, type);

             return getDirectMethod(REF_invokeStatic, refc, method, findBoundCallerClass(method));

         }

         /**

          * Produces a method handle for a virtual method.

          * The type of the method handle will be that of the method,

          * with the receiver type (usually {@code refc}) prepended.

          * The method and all its argument types must be accessible to the lookup object.

          * <p>

          * When called, the handle will treat the first argument as a receiver

          * and dispatch on the receiver's type to determine which method

          * implementation to enter.

          * (The dispatching action is identical with that performed by an

          * {@code invokevirtual} or {@code invokeinterface} instruction.)

          * <p>

          * The first argument will be of type {@code refc} if the lookup

          * class has full privileges to access the member.  Otherwise

          * the member must be {@code protected} and the first argument

          * will be restricted in type to the lookup class.

          * <p>

          * The returned method handle will have

          * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if

          * the method's variable arity modifier bit ({@code 0x0080}) is set.

          * <p>

          * Because of the general <a href="MethodHandles.Lookup.html#equiv">equivalence</a> between {@code invokevirtual}

          * instructions and method handles produced by {@code findVirtual},

          * if the class is {@code MethodHandle} and the name string is

          * {@code invokeExact} or {@code invoke}, the resulting

          * method handle is equivalent to one produced by

          * {@link java.lang.invoke.MethodHandles#exactInvoker MethodHandles.exactInvoker} or

          * {@link java.lang.invoke.MethodHandles#invoker MethodHandles.invoker}

          * with the same {@code type} argument.

          *

          * <b>Example:</b>

          * <blockquote><pre>{@code

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

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

 ...

 MethodHandle MH_concat = publicLookup().findVirtual(String.class,

   "concat", methodType(String.class, String.class));

 MethodHandle MH_hashCode = publicLookup().findVirtual(Object.class,

   "hashCode", methodType(int.class));

 MethodHandle MH_hashCode_String = publicLookup().findVirtual(String.class,

   "hashCode", methodType(int.class));

 assertEquals("xy", (String) MH_concat.invokeExact("x", "y"));

 assertEquals("xy".hashCode(), (int) MH_hashCode.invokeExact((Object)"xy"));

 assertEquals("xy".hashCode(), (int) MH_hashCode_String.invokeExact("xy"));

 // interface method:

 MethodHandle MH_subSequence = publicLookup().findVirtual(CharSequence.class,

   "subSequence", methodType(CharSequence.class, int.class, int.class));

 assertEquals("def", MH_subSequence.invoke("abcdefghi", 3, 6).toString());

 // constructor "internal method" must be accessed differently:

 MethodType MT_newString = methodType(void.class); //()V for new String()

 try { assertEquals("impossible", lookup()

         .findVirtual(String.class, "<init>", MT_newString));

  } catch (NoSuchMethodException ex) { } // OK

 MethodHandle MH_newString = publicLookup()

   .findConstructor(String.class, MT_newString);

 assertEquals("", (String) MH_newString.invokeExact());

          * }</pre></blockquote>

          *

          * @param refc the class or interface from which the method is accessed

          * @param name the name of the method

          * @param type the type of the method, with the receiver argument omitted

          * @return the desired method handle

          * @throws NoSuchMethodException if the method does not exist

          * @throws IllegalAccessException if access checking fails,

          *                                or if the method is {@code static}

          *                                or if the method's variable arity modifier bit

          *                                is set and {@code asVarargsCollector} fails

          * @exception SecurityException if a security manager is present and it

          *                              <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>

          * @throws NullPointerException if any argument is null

          */

         public MethodHandle findVirtual(Class<?> refc, String name, MethodType type) throws NoSuchMethodException, IllegalAccessException {

             if (refc == MethodHandle.class) {

                 MethodHandle mh = findVirtualForMH(name, type);

                 if (mh != null)  return mh;

             }

             byte refKind = (refc.isInterface() ? REF_invokeInterface : REF_invokeVirtual);

             MemberName method = resolveOrFail(refKind, refc, name, type);

             return getDirectMethod(refKind, refc, method, findBoundCallerClass(method));

         }

         private MethodHandle findVirtualForMH(String name, MethodType type) {

             // these names require special lookups because of the implicit MethodType argument

             if ("invoke".equals(name))

                 return invoker(type);

             if ("invokeExact".equals(name))

                 return exactInvoker(type);

             assert(!MemberName.isMethodHandleInvokeName(name));

             return null;

         }

         /**

          * Produces a method handle which creates an object and initializes it, using

          * the constructor of the specified type.

          * The parameter types of the method handle will be those of the constructor,

          * while the return type will be a reference to the constructor's class.

          * The constructor and all its argument types must be accessible to the lookup object.

          * <p>

          * The requested type must have a return type of {@code void}.

          * (This is consistent with the JVM's treatment of constructor type descriptors.)

          * <p>

          * The returned method handle will have

          * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if

          * the constructor's variable arity modifier bit ({@code 0x0080}) is set.

          * <p>

          * If the returned method handle is invoked, the constructor's class will

          * be initialized, if it has not already been initialized.

          * <p><b>Example:</b>

          * <blockquote><pre>{@code

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

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

 ...

 MethodHandle MH_newArrayList = publicLookup().findConstructor(

   ArrayList.class, methodType(void.class, Collection.class));

 Collection orig = Arrays.asList("x", "y");

 Collection copy = (ArrayList) MH_newArrayList.invokeExact(orig);

 assert(orig != copy);

 assertEquals(orig, copy);

 // a variable-arity constructor:

 MethodHandle MH_newProcessBuilder = publicLookup().findConstructor(

   ProcessBuilder.class, methodType(void.class, String[].class));

 ProcessBuilder pb = (ProcessBuilder)

   MH_newProcessBuilder.invoke("x", "y", "z");

 assertEquals("[x, y, z]", pb.command().toString());

          * }</pre></blockquote>

          * @param refc the class or interface from which the method is accessed

          * @param type the type of the method, with the receiver argument omitted, and a void return type

          * @return the desired method handle

          * @throws NoSuchMethodException if the constructor does not exist

          * @throws IllegalAccessException if access checking fails

          *                                or if the method's variable arity modifier bit

          *                                is set and {@code asVarargsCollector} fails

          * @exception SecurityException if a security manager is present and it

          *                              <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>

          * @throws NullPointerException if any argument is null

          */

         public MethodHandle findConstructor(Class<?> refc, MethodType type) throws NoSuchMethodException, IllegalAccessException {

             String name = "<init>";

             MemberName ctor = resolveOrFail(REF_newInvokeSpecial, refc, name, type);

             return getDirectConstructor(refc, ctor);

         }

         /**

          * Produces an early-bound method handle for a virtual method.

          * It will bypass checks for overriding methods on the receiver,

          * <a href="MethodHandles.Lookup.html#equiv">as if called</a> from an {@code invokespecial}

          * instruction from within the explicitly specified {@code specialCaller}.

          * The type of the method handle will be that of the method,

          * with a suitably restricted receiver type prepended.

          * (The receiver type will be {@code specialCaller} or a subtype.)

          * The method and all its argument types must be accessible

          * to the lookup object.

          * <p>

          * Before method resolution,

          * if the explicitly specified caller class is not identical with the

          * lookup class, or if this lookup object does not have

          * <a href="MethodHandles.Lookup.html#privacc">private access</a>

          * privileges, the access fails.

          * <p>

          * The returned method handle will have

          * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if

          * the method's variable arity modifier bit ({@code 0x0080}) is set.

          * <p style="font-size:smaller;">

          * <em>(Note:  JVM internal methods named {@code "<init>"} are not visible to this API,

          * even though the {@code invokespecial} instruction can refer to them

          * in special circumstances.  Use {@link #findConstructor findConstructor}

          * to access instance initialization methods in a safe manner.)</em>

          * <p><b>Example:</b>

          * <blockquote><pre>{@code

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

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

 ...

 static class Listie extends ArrayList {

   public String toString() { return "[wee Listie]"; }

   static Lookup lookup() { return MethodHandles.lookup(); }

 }

 ...

 // no access to constructor via invokeSpecial:

 MethodHandle MH_newListie = Listie.lookup()

   .findConstructor(Listie.class, methodType(void.class));

 Listie l = (Listie) MH_newListie.invokeExact();

 try { assertEquals("impossible", Listie.lookup().findSpecial(

         Listie.class, "<init>", methodType(void.class), Listie.class));

  } catch (NoSuchMethodException ex) { } // OK

 // access to super and self methods via invokeSpecial:

 MethodHandle MH_super = Listie.lookup().findSpecial(

   ArrayList.class, "toString" , methodType(String.class), Listie.class);

 MethodHandle MH_this = Listie.lookup().findSpecial(

   Listie.class, "toString" , methodType(String.class), Listie.class);

 MethodHandle MH_duper = Listie.lookup().findSpecial(

   Object.class, "toString" , methodType(String.class), Listie.class);

 assertEquals("[]", (String) MH_super.invokeExact(l));

 assertEquals(""+l, (String) MH_this.invokeExact(l));

 assertEquals("[]", (String) MH_duper.invokeExact(l)); // ArrayList method

 try { assertEquals("inaccessible", Listie.lookup().findSpecial(

         String.class, "toString", methodType(String.class), Listie.class));

  } catch (IllegalAccessException ex) { } // OK

 Listie subl = new Listie() { public String toString() { return "[subclass]"; } };

 assertEquals(""+l, (String) MH_this.invokeExact(subl)); // Listie method

          * }</pre></blockquote>

          *

          * @param refc the class or interface from which the method is accessed

          * @param name the name of the method (which must not be "<init>")

          * @param type the type of the method, with the receiver argument omitted

          * @param specialCaller the proposed calling class to perform the {@code invokespecial}

          * @return the desired method handle

          * @throws NoSuchMethodException if the method does not exist

          * @throws IllegalAccessException if access checking fails

          *                                or if the method's variable arity modifier bit

          *                                is set and {@code asVarargsCollector} fails

          * @exception SecurityException if a security manager is present and it

          *                              <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>

          * @throws NullPointerException if any argument is null

          */

         public MethodHandle findSpecial(Class<?> refc, String name, MethodType type,

                                         Class<?> specialCaller) throws NoSuchMethodException, IllegalAccessException {

             checkSpecialCaller(specialCaller);

             Lookup specialLookup = this.in(specialCaller);

             MemberName method = specialLookup.resolveOrFail(REF_invokeSpecial, refc, name, type);

             return specialLookup.getDirectMethod(REF_invokeSpecial, refc, method, findBoundCallerClass(method));

         }

         /**

          * Produces a method handle giving read access to a non-static field.

          * The type of the method handle will have a return type of the field's

          * value type.

          * The method handle's single argument will be the instance containing

          * the field.

          * Access checking is performed immediately on behalf of the lookup class.

          * @param refc the class or interface from which the method is accessed

          * @param name the field's name

          * @param type the field's type

          * @return a method handle which can load values from the field

          * @throws NoSuchFieldException if the field does not exist

          * @throws IllegalAccessException if access checking fails, or if the field is {@code static}

          * @exception SecurityException if a security manager is present and it

          *                              <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>

          * @throws NullPointerException if any argument is null

          */

         public MethodHandle findGetter(Class<?> refc, String name, Class<?> type) throws NoSuchFieldException, IllegalAccessException {

             MemberName field = resolveOrFail(REF_getField, refc, name, type);

             return getDirectField(REF_getField, refc, field);

         }

         /**

          * Produces a method handle giving write access to a non-static field.

          * The type of the method handle will have a void return type.

          * The method handle will take two arguments, the instance containing

          * the field, and the value to be stored.

          * The second argument will be of the field's value type.

          * Access checking is performed immediately on behalf of the lookup class.

          * @param refc the class or interface from which the method is accessed

          * @param name the field's name

          * @param type the field's type

          * @return a method handle which can store values into the field

          * @throws NoSuchFieldException if the field does not exist

          * @throws IllegalAccessException if access checking fails, or if the field is {@code static}

          * @exception SecurityException if a security manager is present and it

          *                              <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>

          * @throws NullPointerException if any argument is null

          */

         public MethodHandle findSetter(Class<?> refc, String name, Class<?> type) throws NoSuchFieldException, IllegalAccessException {

             MemberName field = resolveOrFail(REF_putField, refc, name, type);

             return getDirectField(REF_putField, refc, field);

         }

         /**

          * Produces a method handle giving read access to a static field.

          * The type of the method handle will have a return type of the field's

          * value type.

          * The method handle will take no arguments.

          * Access checking is performed immediately on behalf of the lookup class.

          * <p>

          * If the returned method handle is invoked, the field's class will

          * be initialized, if it has not already been initialized.

          * @param refc the class or interface from which the method is accessed

          * @param name the field's name

          * @param type the field's type

          * @return a method handle which can load values from the field

          * @throws NoSuchFieldException if the field does not exist

          * @throws IllegalAccessException if access checking fails, or if the field is not {@code static}

          * @exception SecurityException if a security manager is present and it

          *                              <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>

          * @throws NullPointerException if any argument is null

          */

         public MethodHandle findStaticGetter(Class<?> refc, String name, Class<?> type) throws NoSuchFieldException, IllegalAccessException {

             MemberName field = resolveOrFail(REF_getStatic, refc, name, type);

             return getDirectField(REF_getStatic, refc, field);

         }

         /**

          * Produces a method handle giving write access to a static field.

          * The type of the method handle will have a void return type.

          * The method handle will take a single

          * argument, of the field's value type, the value to be stored.

          * Access checking is performed immediately on behalf of the lookup class.

          * <p>

          * If the returned method handle is invoked, the field's class will

          * be initialized, if it has not already been initialized.

          * @param refc the class or interface from which the method is accessed

          * @param name the field's name

          * @param type the field's type

          * @return a method handle which can store values into the field

          * @throws NoSuchFieldException if the field does not exist

          * @throws IllegalAccessException if access checking fails, or if the field is not {@code static}

          * @exception SecurityException if a security manager is present and it

          *                              <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>

          * @throws NullPointerException if any argument is null

          */

         public MethodHandle findStaticSetter(Class<?> refc, String name, Class<?> type) throws NoSuchFieldException, IllegalAccessException {

             MemberName field = resolveOrFail(REF_putStatic, refc, name, type);

             return getDirectField(REF_putStatic, refc, field);

         }

         /**

          * Produces an early-bound method handle for a non-static method.

          * The receiver must have a supertype {@code defc} in which a method

          * of the given name and type is accessible to the lookup class.

          * The method and all its argument types must be accessible to the lookup object.

          * The type of the method handle will be that of the method,

          * without any insertion of an additional receiver parameter.

          * The given receiver will be bound into the method handle,

          * so that every call to the method handle will invoke the

          * requested method on the given receiver.

          * <p>

          * The returned method handle will have

          * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if

          * the method's variable arity modifier bit ({@code 0x0080}) is set

          * <em>and</em> the trailing array argument is not the only argument.

          * (If the trailing array argument is the only argument,

          * the given receiver value will be bound to it.)

          * <p>

          * This is equivalent to the following code:

          * <blockquote><pre>{@code

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

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

 ...

 MethodHandle mh0 = lookup().findVirtual(defc, name, type);

 MethodHandle mh1 = mh0.bindTo(receiver);

 MethodType mt1 = mh1.type();

 if (mh0.isVarargsCollector())

   mh1 = mh1.asVarargsCollector(mt1.parameterType(mt1.parameterCount()-1));

 return mh1;

          * }</pre></blockquote>

          * where {@code defc} is either {@code receiver.getClass()} or a super

          * type of that class, in which the requested method is accessible

          * to the lookup class.

          * (Note that {@code bindTo} does not preserve variable arity.)

          * @param receiver the object from which the method is accessed

          * @param name the name of the method

          * @param type the type of the method, with the receiver argument omitted

          * @return the desired method handle

          * @throws NoSuchMethodException if the method does not exist

          * @throws IllegalAccessException if access checking fails

          *                                or if the method's variable arity modifier bit

          *                                is set and {@code asVarargsCollector} fails

          * @exception SecurityException if a security manager is present and it

          *                              <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>

          * @throws NullPointerException if any argument is null

          * @see MethodHandle#bindTo

          * @see #findVirtual

          */

         public MethodHandle bind(Object receiver, String name, MethodType type) throws NoSuchMethodException, IllegalAccessException {

             Class<? extends Object> refc = receiver.getClass(); // may get NPE

             MemberName method = resolveOrFail(REF_invokeSpecial, refc, name, type);

             MethodHandle mh = getDirectMethodNoRestrict(REF_invokeSpecial, refc, method, findBoundCallerClass(method));

             return mh.bindReceiver(receiver).setVarargs(method);

         }

         /**

          * Makes a <a href="MethodHandleInfo.html#directmh">direct method handle</a>

          * to <i>m</i>, if the lookup class has permission.

          * If <i>m</i> is non-static, the receiver argument is treated as an initial argument.

          * If <i>m</i> is virtual, overriding is respected on every call.

          * Unlike the Core Reflection API, exceptions are <em>not</em> wrapped.

          * The type of the method handle will be that of the method,

          * with the receiver type prepended (but only if it is non-static).

          * If the method's {@code accessible} flag is not set,

          * access checking is performed immediately on behalf of the lookup class.

          * If <i>m</i> is not public, do not share the resulting handle with untrusted parties.

          * <p>

          * The returned method handle will have

          * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if

          * the method's variable arity modifier bit ({@code 0x0080}) is set.

          * <p>

          * If <i>m</i> is static, and

          * if the returned method handle is invoked, the method's class will

          * be initialized, if it has not already been initialized.

          * @param m the reflected method

          * @return a method handle which can invoke the reflected method

          * @throws IllegalAccessException if access checking fails

          *                                or if the method's variable arity modifier bit

          *                                is set and {@code asVarargsCollector} fails

          * @throws NullPointerException if the argument is null

          */

         public MethodHandle unreflect(Method m) throws IllegalAccessException {

             if (m.getDeclaringClass() == MethodHandle.class) {

                 MethodHandle mh = unreflectForMH(m);

                 if (mh != null)  return mh;

             }

             MemberName method = new MemberName(m);

             byte refKind = method.getReferenceKind();

             if (refKind == REF_invokeSpecial)

                 refKind = REF_invokeVirtual;

             assert(method.isMethod());

             Lookup lookup = m.isAccessible() ? IMPL_LOOKUP : this;

             return lookup.getDirectMethodNoSecurityManager(refKind, method.getDeclaringClass(), method, findBoundCallerClass(method));

         }

         private MethodHandle unreflectForMH(Method m) {

             // these names require special lookups because they throw UnsupportedOperationException

             if (MemberName.isMethodHandleInvokeName(m.getName()))

                 return MethodHandleImpl.fakeMethodHandleInvoke(new MemberName(m));

             return null;

         }

         /**

          * Produces a method handle for a reflected method.

          * It will bypass checks for overriding methods on the receiver,

          * <a href="MethodHandles.Lookup.html#equiv">as if called</a> from an {@code invokespecial}

          * instruction from within the explicitly specified {@code specialCaller}.

          * The type of the method handle will be that of the method,

          * with a suitably restricted receiver type prepended.

          * (The receiver type will be {@code specialCaller} or a subtype.)

          * If the method's {@code accessible} flag is not set,

          * access checking is performed immediately on behalf of the lookup class,

          * as if {@code invokespecial} instruction were being linked.

          * <p>

          * Before method resolution,

          * if the explicitly specified caller class is not identical with the

          * lookup class, or if this lookup object does not have

          * <a href="MethodHandles.Lookup.html#privacc">private access</a>

          * privileges, the access fails.

          * <p>

          * The returned method handle will have

          * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if

          * the method's variable arity modifier bit ({@code 0x0080}) is set.

          * @param m the reflected method

          * @param specialCaller the class nominally calling the method

          * @return a method handle which can invoke the reflected method

          * @throws IllegalAccessException if access checking fails

          *                                or if the method's variable arity modifier bit

          *                                is set and {@code asVarargsCollector} fails

          * @throws NullPointerException if any argument is null

          */

         public MethodHandle unreflectSpecial(Method m, Class<?> specialCaller) throws IllegalAccessException {

             checkSpecialCaller(specialCaller);

             Lookup specialLookup = this.in(specialCaller);

             MemberName method = new MemberName(m, true);

             assert(method.isMethod());

             // ignore m.isAccessible:  this is a new kind of access

             return specialLookup.getDirectMethodNoSecurityManager(REF_invokeSpecial, method.getDeclaringClass(), method, findBoundCallerClass(method));

         }

         /**

          * Produces a method handle for a reflected constructor.

          * The type of the method handle will be that of the constructor,

          * with the return type changed to the declaring class.

          * The method handle will perform a {@code newInstance} operation,

          * creating a new instance of the constructor's class on the

          * arguments passed to the method handle.

          * <p>

          * If the constructor's {@code accessible} flag is not set,

          * access checking is performed immediately on behalf of the lookup class.

          * <p>

          * The returned method handle will have

          * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if

          * the constructor's variable arity modifier bit ({@code 0x0080}) is set.

          * <p>

          * If the returned method handle is invoked, the constructor's class will

          * be initialized, if it has not already been initialized.

          * @param c the reflected constructor

          * @return a method handle which can invoke the reflected constructor

          * @throws IllegalAccessException if access checking fails

          *                                or if the method's variable arity modifier bit

          *                                is set and {@code asVarargsCollector} fails

          * @throws NullPointerException if the argument is null

          */

         public MethodHandle unreflectConstructor(Constructor<?> c) throws IllegalAccessException {

             MemberName ctor = new MemberName(c);

             assert(ctor.isConstructor());

             Lookup lookup = c.isAccessible() ? IMPL_LOOKUP : this;

             return lookup.getDirectConstructorNoSecurityManager(ctor.getDeclaringClass(), ctor);

         }

         /**

          * Produces a method handle giving read access to a reflected field.

          * The type of the method handle will have a return type of the field's

          * value type.

          * If the field is static, the method handle will take no arguments.

          * Otherwise, its single argument will be the instance containing

          * the field.

          * If the field's {@code accessible} flag is not set,

          * access checking is performed immediately on behalf of the lookup class.

          * <p>

          * If the field is static, and

          * if the returned method handle is invoked, the field's class will

          * be initialized, if it has not already been initialized.

          * @param f the reflected field

          * @return a method handle which can load values from the reflected field

          * @throws IllegalAccessException if access checking fails

          * @throws NullPointerException if the argument is null

          */

         public MethodHandle unreflectGetter(Field f) throws IllegalAccessException {

             return unreflectField(f, false);

         }

         private MethodHandle unreflectField(Field f, boolean isSetter) throws IllegalAccessException {

             MemberName field = new MemberName(f, isSetter);

             assert(isSetter

                     ? MethodHandleNatives.refKindIsSetter(field.getReferenceKind())

                     : MethodHandleNatives.refKindIsGetter(field.getReferenceKind()));

             Lookup lookup = f.isAccessible() ? IMPL_LOOKUP : this;

             return lookup.getDirectFieldNoSecurityManager(field.getReferenceKind(), f.getDeclaringClass(), field);

         }

         /**

          * Produces a method handle giving write access to a reflected field.

          * The type of the method handle will have a void return type.

          * If the field is static, the method handle will take a single

          * argument, of the field's value type, the value to be stored.

          * Otherwise, the two arguments will be the instance containing

          * the field, and the value to be stored.

          * If the field's {@code accessible} flag is not set,

          * access checking is performed immediately on behalf of the lookup class.

          * <p>

          * If the field is static, and

          * if the returned method handle is invoked, the field's class will

          * be initialized, if it has not already been initialized.

          * @param f the reflected field

          * @return a method handle which can store values into the reflected field

          * @throws IllegalAccessException if access checking fails

          * @throws NullPointerException if the argument is null

          */

         public MethodHandle unreflectSetter(Field f) throws IllegalAccessException {

             return unreflectField(f, true);

         }

         /**

          * Cracks a <a href="MethodHandleInfo.html#directmh">direct method handle</a>

          * created by this lookup object or a similar one.

          * Security and access checks are performed to ensure that this lookup object

          * is capable of reproducing the target method handle.

          * This means that the cracking may fail if target is a direct method handle

          * but was created by an unrelated lookup object.

          * This can happen if the method handle is <a href="MethodHandles.Lookup.html#callsens">caller sensitive</a>

          * and was created by a lookup object for a different class.

          * @param target a direct method handle to crack into symbolic reference components

          * @return a symbolic reference which can be used to reconstruct this method handle from this lookup object

          * @exception SecurityException if a security manager is present and it

          *                              <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>

          * @throws IllegalArgumentException if the target is not a direct method handle or if access checking fails

          * @exception NullPointerException if the target is {@code null}

          * @see MethodHandleInfo

          * @since 1.8

          */

         public MethodHandleInfo revealDirect(MethodHandle target) {

             MemberName member = target.internalMemberName();

             if (member == null || (!member.isResolved() && !member.isMethodHandleInvoke()))

                 throw newIllegalArgumentException("not a direct method handle");

             Class<?> defc = member.getDeclaringClass();

             byte refKind = member.getReferenceKind();

             assert(MethodHandleNatives.refKindIsValid(refKind));

             if (refKind == REF_invokeSpecial && !target.isInvokeSpecial())

                 // Devirtualized method invocation is usually formally virtual.

                 // To avoid creating extra MemberName objects for this common case,

                 // we encode this extra degree of freedom using MH.isInvokeSpecial.

                 refKind = REF_invokeVirtual;

             if (refKind == REF_invokeVirtual && defc.isInterface())

                 // Symbolic reference is through interface but resolves to Object method (toString, etc.)

                 refKind = REF_invokeInterface;

             // Check SM permissions and member access before cracking.

             try {

                 checkAccess(refKind, defc, member);

                 checkSecurityManager(defc, member);

             } catch (IllegalAccessException ex) {

                 throw new IllegalArgumentException(ex);

             }

             if (allowedModes != TRUSTED && member.isCallerSensitive()) {

                 Class<?> callerClass = target.internalCallerClass();

                 if (!hasPrivateAccess() || callerClass != lookupClass())

                     throw new IllegalArgumentException("method handle is caller sensitive: "+callerClass);

             }

             // Produce the handle to the results.

             return new InfoFromMemberName(this, member, refKind);

         }

         /// Helper methods, all package-private.

         MemberName resolveOrFail(byte refKind, Class<?> refc, String name, Class<?> type) throws NoSuchFieldException, IllegalAccessException {

             checkSymbolicClass(refc);  // do this before attempting to resolve

             name.getClass();  // NPE

             type.getClass();  // NPE

             return IMPL_NAMES.resolveOrFail(refKind, new MemberName(refc, name, type, refKind), lookupClassOrNull(),

                                             NoSuchFieldException.class);

         }

         MemberName resolveOrFail(byte refKind, Class<?> refc, String name, MethodType type) throws NoSuchMethodException, IllegalAccessException {

             checkSymbolicClass(refc);  // do this before attempting to resolve

             name.getClass();  // NPE

             type.getClass();  // NPE

             checkMethodName(refKind, name);  // NPE check on name

             return IMPL_NAMES.resolveOrFail(refKind, new MemberName(refc, name, type, refKind), lookupClassOrNull(),

                                             NoSuchMethodException.class);

         }

         MemberName resolveOrFail(byte refKind, MemberName member) throws ReflectiveOperationException {

             checkSymbolicClass(member.getDeclaringClass());  // do this before attempting to resolve

             member.getName().getClass();  // NPE

             member.getType().getClass();  // NPE

             return IMPL_NAMES.resolveOrFail(refKind, member, lookupClassOrNull(),

                                             ReflectiveOperationException.class);

         }

         void checkSymbolicClass(Class<?> refc) throws IllegalAccessException {

             refc.getClass();  // NPE

             Class<?> caller = lookupClassOrNull();

             if (caller != null && !VerifyAccess.isClassAccessible(refc, caller, allowedModes))

                 throw new MemberName(refc).makeAccessException("symbolic reference class is not public", this);

         }

         /** Check name for an illegal leading "<" character. */

         void checkMethodName(byte refKind, String name) throws NoSuchMethodException {

             if (name.startsWith("<") && refKind != REF_newInvokeSpecial)

                 throw new NoSuchMethodException("illegal method name: "+name);

         }

         /**

          * Find my trustable caller class if m is a caller sensitive method.

          * If this lookup object has private access, then the caller class is the lookupClass.

          * Otherwise, if m is caller-sensitive, throw IllegalAccessException.

          */

         Class<?> findBoundCallerClass(MemberName m) throws IllegalAccessException {

             Class<?> callerClass = null;

             if (MethodHandleNatives.isCallerSensitive(m)) {

                 // Only lookups with private access are allowed to resolve caller-sensitive methods

                 if (hasPrivateAccess()) {

                     callerClass = lookupClass;

                 } else {

                     throw new IllegalAccessException("Attempt to lookup caller-sensitive method using restricted lookup object");

                 }

             }

             return callerClass;

         }

         private boolean hasPrivateAccess() {

             return (allowedModes & PRIVATE) != 0;

         }

         /**

          * Perform necessary <a href="MethodHandles.Lookup.html#secmgr">access checks</a>.

          * Determines a trustable caller class to compare with refc, the symbolic reference class.

          * If this lookup object has private access, then the caller class is the lookupClass.

          */

         void checkSecurityManager(Class<?> refc, MemberName m) {

 //            SecurityManager smgr = System.getSecurityManager();

 //            if (smgr == null)  return;

 //            if (allowedModes == TRUSTED)  return;

 //

 //            // Step 1:

 //            boolean fullPowerLookup = hasPrivateAccess();

 //            if (!fullPowerLookup ||

 //                !VerifyAccess.classLoaderIsAncestor(lookupClass, refc)) {

 //                ReflectUtil.checkPackageAccess(refc);

 //            }

 //

 //            // Step 2:

 //            if (m.isPublic()) return;

 //            if (!fullPowerLookup) {

 //                smgr.checkPermission(SecurityConstants.CHECK_MEMBER_ACCESS_PERMISSION);

 //            }

 //

 //            // Step 3:

 //            Class<?> defc = m.getDeclaringClass();

 //            if (!fullPowerLookup && defc != refc) {

 //                ReflectUtil.checkPackageAccess(defc);

 //            }

         }

         void checkMethod(byte refKind, Class<?> refc, MemberName m) throws IllegalAccessException {

             boolean wantStatic = (refKind == REF_invokeStatic);

             String message;

             if (m.isConstructor())

                 message = "expected a method, not a constructor";

             else if (!m.isMethod())

                 message = "expected a method";

             else if (wantStatic != m.isStatic())

                 message = wantStatic ? "expected a static method" : "expected a non-static method";

             else

                 { checkAccess(refKind, refc, m); return; }

             throw m.makeAccessException(message, this);

         }

         void checkField(byte refKind, Class<?> refc, MemberName m) throws IllegalAccessException {

             boolean wantStatic = !MethodHandleNatives.refKindHasReceiver(refKind);

             String message;

             if (wantStatic != m.isStatic())

                 message = wantStatic ? "expected a static field" : "expected a non-static field";

             else

                 { checkAccess(refKind, refc, m); return; }

             throw m.makeAccessException(message, this);

         }

         /** Check public/protected/private bits on the symbolic reference class and its member. */

         void checkAccess(byte refKind, Class<?> refc, MemberName m) throws IllegalAccessException {

             assert(m.referenceKindIsConsistentWith(refKind) &&

                    MethodHandleNatives.refKindIsValid(refKind) &&

                    (MethodHandleNatives.refKindIsField(refKind) == m.isField()));

             int allowedModes = this.allowedModes;

             if (allowedModes == TRUSTED)  return;

             int mods = m.getModifiers();

             if (Modifier.isProtected(mods) &&

                     refKind == REF_invokeVirtual &&

                     m.getDeclaringClass() == Object.class &&

                     m.getName().equals("clone") &&

                     refc.isArray()) {

                 // The JVM does this hack also.

                 // (See ClassVerifier::verify_invoke_instructions

                 // and LinkResolver::check_method_accessability.)

                 // Because the JVM does not allow separate methods on array types,

                 // there is no separate method for int[].clone.

                 // All arrays simply inherit Object.clone.

                 // But for access checking logic, we make Object.clone

                 // (normally protected) appear to be public.

                 // Later on, when the DirectMethodHandle is created,

                 // its leading argument will be restricted to the

                 // requested array type.

                 // N.B. The return type is not adjusted, because

                 // that is *not* the bytecode behavior.

                 mods ^= Modifier.PROTECTED | Modifier.PUBLIC;

             }

             if (Modifier.isFinal(mods) &&

                     MethodHandleNatives.refKindIsSetter(refKind))

                 throw m.makeAccessException("unexpected set of a final field", this);

             if (Modifier.isPublic(mods) && Modifier.isPublic(refc.getModifiers()) && allowedModes != 0)

                 return;  // common case

             int requestedModes = fixmods(mods);  // adjust 0 => PACKAGE

             if ((requestedModes & allowedModes) != 0) {

                 if (VerifyAccess.isMemberAccessible(refc, m.getDeclaringClass(),

                                                     mods, lookupClass(), allowedModes))

                     return;

             } else {

                 // Protected members can also be checked as if they were package-private.

                 if ((requestedModes & PROTECTED) != 0 && (allowedModes & PACKAGE) != 0

                         && VerifyAccess.isSamePackage(m.getDeclaringClass(), lookupClass()))

                     return;

             }

             throw m.makeAccessException(accessFailedMessage(refc, m), this);

         }

         String accessFailedMessage(Class<?> refc, MemberName m) {

             Class<?> defc = m.getDeclaringClass();

             int mods = m.getModifiers();

             // check the class first:

             boolean classOK = (Modifier.isPublic(defc.getModifiers()) &&

                                (defc == refc ||

                                 Modifier.isPublic(refc.getModifiers())));

             if (!classOK && (allowedModes & PACKAGE) != 0) {

                 classOK = (VerifyAccess.isClassAccessible(defc, lookupClass(), ALL_MODES) &&

                            (defc == refc ||

                             VerifyAccess.isClassAccessible(refc, lookupClass(), ALL_MODES)));

             }

             if (!classOK)

                 return "class is not public";

             if (Modifier.isPublic(mods))

                 return "access to public member failed";  // (how?)

             if (Modifier.isPrivate(mods))

                 return "member is private";

             if (Modifier.isProtected(mods))

                 return "member is protected";

             return "member is private to package";

         }

         private static final boolean ALLOW_NESTMATE_ACCESS = false;

         private void checkSpecialCaller(Class<?> specialCaller) throws IllegalAccessException {

             int allowedModes = this.allowedModes;

             if (allowedModes == TRUSTED)  return;

             if (!hasPrivateAccess()

                 || (specialCaller != lookupClass()

                     && !(ALLOW_NESTMATE_ACCESS &&

                          VerifyAccess.isSamePackageMember(specialCaller, lookupClass()))))

                 throw new MemberName(specialCaller).

                     makeAccessException("no private access for invokespecial", this);

         }

         private boolean restrictProtectedReceiver(MemberName method) {

             // The accessing class only has the right to use a protected member

             // on itself or a subclass.  Enforce that restriction, from JVMS 5.4.4, etc.

             if (!method.isProtected() || method.isStatic()

                 || allowedModes == TRUSTED

                 || method.getDeclaringClass() == lookupClass()

                 || VerifyAccess.isSamePackage(method.getDeclaringClass(), lookupClass())

                 || (ALLOW_NESTMATE_ACCESS &&

                     VerifyAccess.isSamePackageMember(method.getDeclaringClass(), lookupClass())))

                 return false;

             return true;

         }

         private MethodHandle restrictReceiver(MemberName method, MethodHandle mh, Class<?> caller) throws IllegalAccessException {

             assert(!method.isStatic());

             // receiver type of mh is too wide; narrow to caller

             if (!method.getDeclaringClass().isAssignableFrom(caller)) {

                 throw method.makeAccessException("caller class must be a subclass below the method", caller);

             }

             MethodType rawType = mh.type();

             if (rawType.parameterType(0) == caller)  return mh;

             MethodType narrowType = rawType.changeParameterType(0, caller);

             return mh.viewAsType(narrowType);

         }

         /** Check access and get the requested method. */

         private MethodHandle getDirectMethod(byte refKind, Class<?> refc, MemberName method, Class<?> callerClass) throws IllegalAccessException {

             final boolean doRestrict    = true;

             final boolean checkSecurity = true;

             return getDirectMethodCommon(refKind, refc, method, checkSecurity, doRestrict, callerClass);

         }

         /** Check access and get the requested method, eliding receiver narrowing rules. */

         private MethodHandle getDirectMethodNoRestrict(byte refKind, Class<?> refc, MemberName method, Class<?> callerClass) throws IllegalAccessException {

             final boolean doRestrict    = false;

             final boolean checkSecurity = true;

             return getDirectMethodCommon(refKind, refc, method, checkSecurity, doRestrict, callerClass);

         }

         /** Check access and get the requested method, eliding security manager checks. */

         private MethodHandle getDirectMethodNoSecurityManager(byte refKind, Class<?> refc, MemberName method, Class<?> callerClass) throws IllegalAccessException {

             final boolean doRestrict    = true;

             final boolean checkSecurity = false;  // not needed for reflection or for linking CONSTANT_MH constants

             return getDirectMethodCommon(refKind, refc, method, checkSecurity, doRestrict, callerClass);

         }

         /** Common code for all methods; do not call directly except from immediately above. */

         private MethodHandle getDirectMethodCommon(byte refKind, Class<?> refc, MemberName method,

                                                    boolean checkSecurity,

                                                    boolean doRestrict, Class<?> callerClass) throws IllegalAccessException {

             checkMethod(refKind, refc, method);

             // Optionally check with the security manager; this isn't needed for unreflect* calls.

             if (checkSecurity)

                 checkSecurityManager(refc, method);

             assert(!method.isMethodHandleInvoke());

             Class<?> refcAsSuper;

             if (refKind == REF_invokeSpecial &&

                 refc != lookupClass() &&

                 !refc.isInterface() &&

                 refc != (refcAsSuper = lookupClass().getSuperclass()) &&

                 refc.isAssignableFrom(lookupClass())) {

                 assert(!method.getName().equals("<init>"));  // not this code path

                 // Per JVMS 6.5, desc. of invokespecial instruction:

                 // If the method is in a superclass of the LC,

                 // and if our original search was above LC.super,

                 // repeat the search (symbolic lookup) from LC.super.

                 // FIXME: MemberName.resolve should handle this instead.

                 MemberName m2 = new MemberName(refcAsSuper,

                                                method.getName(),

                                                method.getMethodType(),

                                                REF_invokeSpecial);

                 m2 = IMPL_NAMES.resolveOrNull(refKind, m2, lookupClassOrNull());

                 if (m2 == null)  throw new InternalError(method.toString());

                 method = m2;

                 refc = refcAsSuper;

                 // redo basic checks

                 checkMethod(refKind, refc, method);

             }

             MethodHandle mh = DirectMethodHandle.make(refKind, refc, method);

             mh = maybeBindCaller(method, mh, callerClass);

             mh = mh.setVarargs(method);

             // Optionally narrow the receiver argument to refc using restrictReceiver.

             if (doRestrict &&

                    (refKind == REF_invokeSpecial ||

                        (MethodHandleNatives.refKindHasReceiver(refKind) &&

                            restrictProtectedReceiver(method))))

                 mh = restrictReceiver(method, mh, lookupClass());

             return mh;

         }

         private MethodHandle maybeBindCaller(MemberName method, MethodHandle mh,

                                              Class<?> callerClass)

                                              throws IllegalAccessException {

             if (allowedModes == TRUSTED || !MethodHandleNatives.isCallerSensitive(method))

                 return mh;

             Class<?> hostClass = lookupClass;

             if (!hasPrivateAccess())  // caller must have private access

                 hostClass = callerClass;  // callerClass came from a security manager style stack walk

             MethodHandle cbmh = MethodHandleImpl.bindCaller(mh, hostClass);

             // Note: caller will apply varargs after this step happens.

             return cbmh;

         }

         /** Check access and get the requested field. */

         private MethodHandle getDirectField(byte refKind, Class<?> refc, MemberName field) throws IllegalAccessException {

             final boolean checkSecurity = true;

             return getDirectFieldCommon(refKind, refc, field, checkSecurity);

         }

         /** Check access and get the requested field, eliding security manager checks. */

         private MethodHandle getDirectFieldNoSecurityManager(byte refKind, Class<?> refc, MemberName field) throws IllegalAccessException {

             final boolean checkSecurity = false;  // not needed for reflection or for linking CONSTANT_MH constants

             return getDirectFieldCommon(refKind, refc, field, checkSecurity);

         }

         /** Common code for all fields; do not call directly except from immediately above. */

         private MethodHandle getDirectFieldCommon(byte refKind, Class<?> refc, MemberName field,

                                                   boolean checkSecurity) throws IllegalAccessException {

             checkField(refKind, refc, field);

             // Optionally check with the security manager; this isn't needed for unreflect* calls.

             if (checkSecurity)

                 checkSecurityManager(refc, field);

             MethodHandle mh = DirectMethodHandle.make(refc, field);

             boolean doRestrict = (MethodHandleNatives.refKindHasReceiver(refKind) &&

                                     restrictProtectedReceiver(field));

             if (doRestrict)

                 mh = restrictReceiver(field, mh, lookupClass());

             return mh;

         }

         /** Check access and get the requested constructor. */

         private MethodHandle getDirectConstructor(Class<?> refc, MemberName ctor) throws IllegalAccessException {

             final boolean checkSecurity = true;

             return getDirectConstructorCommon(refc, ctor, checkSecurity);

         }

         /** Check access and get the requested constructor, eliding security manager checks. */

         private MethodHandle getDirectConstructorNoSecurityManager(Class<?> refc, MemberName ctor) throws IllegalAccessException {

             final boolean checkSecurity = false;  // not needed for reflection or for linking CONSTANT_MH constants

             return getDirectConstructorCommon(refc, ctor, checkSecurity);

         }

         /** Common code for all constructors; do not call directly except from immediately above. */

         private MethodHandle getDirectConstructorCommon(Class<?> refc, MemberName ctor,

                                                   boolean checkSecurity) throws IllegalAccessException {

             assert(ctor.isConstructor());

             checkAccess(REF_newInvokeSpecial, refc, ctor);

             // Optionally check with the security manager; this isn't needed for unreflect* calls.

             if (checkSecurity)

                 checkSecurityManager(refc, ctor);

             assert(!MethodHandleNatives.isCallerSensitive(ctor));  // maybeBindCaller not relevant here

             return DirectMethodHandle.make(ctor).setVarargs(ctor);

         }

         /** Hook called from the JVM (via MethodHandleNatives) to link MH constants:

          */

         /*non-public*/

         MethodHandle linkMethodHandleConstant(byte refKind, Class<?> defc, String name, Object type) throws ReflectiveOperationException {

             if (!(type instanceof Class || type instanceof MethodType))

                 throw new InternalError("unresolved MemberName");

             MemberName member = new MemberName(refKind, defc, name, type);

             MethodHandle mh = LOOKASIDE_TABLE.get(member);

             if (mh != null) {

                 checkSymbolicClass(defc);

                 return mh;

             }

             // Treat MethodHandle.invoke and invokeExact specially.

             if (defc == MethodHandle.class && refKind == REF_invokeVirtual) {

                 mh = findVirtualForMH(member.getName(), member.getMethodType());

                 if (mh != null) {

                     return mh;

                 }

             }

             MemberName resolved = resolveOrFail(refKind, member);

             mh = getDirectMethodForConstant(refKind, defc, resolved);

             if (mh instanceof DirectMethodHandle

                     && canBeCached(refKind, defc, resolved)) {

                 MemberName key = mh.internalMemberName();

                 if (key != null) {

                     key = key.asNormalOriginal();

                 }

                 if (member.equals(key)) {  // better safe than sorry

                     LOOKASIDE_TABLE.put(key, (DirectMethodHandle) mh);

                 }

             }

             return mh;

         }

         private

         boolean canBeCached(byte refKind, Class<?> defc, MemberName member) {

             if (refKind == REF_invokeSpecial) {

                 return false;

             }

             if (!Modifier.isPublic(defc.getModifiers()) ||

                     !Modifier.isPublic(member.getDeclaringClass().getModifiers()) ||

                     !member.isPublic() ||

                     member.isCallerSensitive()) {

                 return false;

             }

             ClassLoader loader = defc.getClassLoader();

 //            if (!sun.misc.VM.isSystemDomainLoader(loader)) {

 //                ClassLoader sysl = ClassLoader.getSystemClassLoader();

 //                boolean found = false;

 //                while (sysl != null) {

 //                    if (loader == sysl) { found = true; break; }

 //                    sysl = sysl.getParent();

 //                }

 //                if (!found) {

 //                    return false;

 //                }

 //            }

             try {

                 MemberName resolved2 = publicLookup().resolveOrFail(refKind,

                     new MemberName(refKind, defc, member.getName(), member.getType()));

                 checkSecurityManager(defc, resolved2);

             } catch (ReflectiveOperationException | SecurityException ex) {

                 return false;

             }

             return true;

         }

         private

         MethodHandle getDirectMethodForConstant(byte refKind, Class<?> defc, MemberName member)

                 throws ReflectiveOperationException {

             if (MethodHandleNatives.refKindIsField(refKind)) {

                 return getDirectFieldNoSecurityManager(refKind, defc, member);

             } else if (MethodHandleNatives.refKindIsMethod(refKind)) {

                 return getDirectMethodNoSecurityManager(refKind, defc, member, lookupClass);

             } else if (refKind == REF_newInvokeSpecial) {

                 return getDirectConstructorNoSecurityManager(defc, member);

             }

             // oops

             throw newIllegalArgumentException("bad MethodHandle constant #"+member);

         }

         static ConcurrentHashMap<MemberName, DirectMethodHandle> LOOKASIDE_TABLE = new ConcurrentHashMap<>();

     }

     /**

      * Produces a method handle giving read access to elements of an array.

      * The type of the method handle will have a return type of the array's

      * element type.  Its first argument will be the array type,

      * and the second will be {@code int}.

      * @param arrayClass an array type

      * @return a method handle which can load values from the given array type

      * @throws NullPointerException if the argument is null

      * @throws  IllegalArgumentException if arrayClass is not an array type

      */

     public static

     MethodHandle arrayElementGetter(Class<?> arrayClass) throws IllegalArgumentException {

         return MethodHandleImpl.makeArrayElementAccessor(arrayClass, false);

     }

     /**

      * Produces a method handle giving write access to elements of an array.

      * The type of the method handle will have a void return type.

      * Its last argument will be the array's element type.

      * The first and second arguments will be the array type and int.

      * @param arrayClass the class of an array

      * @return a method handle which can store values into the array type

      * @throws NullPointerException if the argument is null

      * @throws IllegalArgumentException if arrayClass is not an array type

      */

     public static

     MethodHandle arrayElementSetter(Class<?> arrayClass) throws IllegalArgumentException {

         return MethodHandleImpl.makeArrayElementAccessor(arrayClass, true);

     }

     /// method handle invocation (reflective style)

     /**

      * Produces a method handle which will invoke any method handle of the

      * given {@code type}, with a given number of trailing arguments replaced by

      * a single trailing {@code Object[]} array.

      * The resulting invoker will be a method handle with the following

      * arguments:

      * <ul>

      * <li>a single {@code MethodHandle} target

      * <li>zero or more leading values (counted by {@code leadingArgCount})

      * <li>an {@code Object[]} array containing trailing arguments

      * </ul>

      * <p>

      * The invoker will invoke its target like a call to {@link MethodHandle#invoke invoke} with

      * the indicated {@code type}.

      * That is, if the target is exactly of the given {@code type}, it will behave

      * like {@code invokeExact}; otherwise it behave as if {@link MethodHandle#asType asType}

      * is used to convert the target to the required {@code type}.

      * <p>

      * The type of the returned invoker will not be the given {@code type}, but rather

      * will have all parameters except the first {@code leadingArgCount}

      * replaced by a single array of type {@code Object[]}, which will be

      * the final parameter.

      * <p>

      * Before invoking its target, the invoker will spread the final array, apply

      * reference casts as necessary, and unbox and widen primitive arguments.

      * If, when the invoker is called, the supplied array argument does

      * not have the correct number of elements, the invoker will throw

      * an {@link IllegalArgumentException} instead of invoking the target.

      * <p>

      * This method is equivalent to the following code (though it may be more efficient):

      * <blockquote><pre>{@code

 MethodHandle invoker = MethodHandles.invoker(type);

 int spreadArgCount = type.parameterCount() - leadingArgCount;

 invoker = invoker.asSpreader(Object[].class, spreadArgCount);

 return invoker;

      * }</pre></blockquote>

      * This method throws no reflective or security exceptions.

      * @param type the desired target type

      * @param leadingArgCount number of fixed arguments, to be passed unchanged to the target

      * @return a method handle suitable for invoking any method handle of the given type

      * @throws NullPointerException if {@code type} is null

      * @throws IllegalArgumentException if {@code leadingArgCount} is not in

      *                  the range from 0 to {@code type.parameterCount()} inclusive,

      *                  or if the resulting method handle's type would have

      *          <a href="MethodHandle.html#maxarity">too many parameters</a>

      */

     static public

     MethodHandle spreadInvoker(MethodType type, int leadingArgCount) {

         if (leadingArgCount < 0 || leadingArgCount > type.parameterCount())

             throw new IllegalArgumentException("bad argument count "+leadingArgCount);

         return type.invokers().spreadInvoker(leadingArgCount);

     }

     /**

      * Produces a special <em>invoker method handle</em> which can be used to

      * invoke any method handle of the given type, as if by {@link MethodHandle#invokeExact invokeExact}.

      * The resulting invoker will have a type which is

      * exactly equal to the desired type, except that it will accept

      * an additional leading argument of type {@code MethodHandle}.

      * <p>

      * This method is equivalent to the following code (though it may be more efficient):

      * {@code publicLookup().findVirtual(MethodHandle.class, "invokeExact", type)}

      *

      * <p style="font-size:smaller;">

      * <em>Discussion:</em>

      * Invoker method handles can be useful when working with variable method handles

      * of unknown types.

      * For example, to emulate an {@code invokeExact} call to a variable method

      * handle {@code M}, extract its type {@code T},

      * look up the invoker method {@code X} for {@code T},

      * and call the invoker method, as {@code X.invoke(T, A...)}.

      * (It would not work to call {@code X.invokeExact}, since the type {@code T}

      * is unknown.)

      * If spreading, collecting, or other argument transformations are required,

      * they can be applied once to the invoker {@code X} and reused on many {@code M}

      * method handle values, as long as they are compatible with the type of {@code X}.

      * <p style="font-size:smaller;">

      * <em>(Note:  The invoker method is not available via the Core Reflection API.

      * An attempt to call {@linkplain java.lang.reflect.Method#invoke java.lang.reflect.Method.invoke}

      * on the declared {@code invokeExact} or {@code invoke} method will raise an

      * {@link java.lang.UnsupportedOperationException UnsupportedOperationException}.)</em>

      * <p>

      * This method throws no reflective or security exceptions.

      * @param type the desired target type

      * @return a method handle suitable for invoking any method handle of the given type

      * @throws IllegalArgumentException if the resulting method handle's type would have

      *          <a href="MethodHandle.html#maxarity">too many parameters</a>

      */

     static public

     MethodHandle exactInvoker(MethodType type) {

         return type.invokers().exactInvoker();

     }

     /**

      * Produces a special <em>invoker method handle</em> which can be used to

      * invoke any method handle compatible with the given type, as if by {@link MethodHandle#invoke invoke}.

      * The resulting invoker will have a type which is

      * exactly equal to the desired type, except that it will accept

      * an additional leading argument of type {@code MethodHandle}.

      * <p>

      * Before invoking its target, if the target differs from the expected type,

      * the invoker will apply reference casts as

      * necessary and box, unbox, or widen primitive values, as if by {@link MethodHandle#asType asType}.

      * Similarly, the return value will be converted as necessary.

      * If the target is a {@linkplain MethodHandle#asVarargsCollector variable arity method handle},

      * the required arity conversion will be made, again as if by {@link MethodHandle#asType asType}.

      * <p>

      * This method is equivalent to the following code (though it may be more efficient):

      * {@code publicLookup().findVirtual(MethodHandle.class, "invoke", type)}

      * <p style="font-size:smaller;">

      * <em>Discussion:</em>

      * A {@linkplain MethodType#genericMethodType general method type} is one which

      * mentions only {@code Object} arguments and return values.

      * An invoker for such a type is capable of calling any method handle

      * of the same arity as the general type.

      * <p style="font-size:smaller;">

      * <em>(Note:  The invoker method is not available via the Core Reflection API.

      * An attempt to call {@linkplain java.lang.reflect.Method#invoke java.lang.reflect.Method.invoke}

      * on the declared {@code invokeExact} or {@code invoke} method will raise an

      * {@link java.lang.UnsupportedOperationException UnsupportedOperationException}.)</em>

      * <p>

      * This method throws no reflective or security exceptions.

      * @param type the desired target type

      * @return a method handle suitable for invoking any method handle convertible to the given type

      * @throws IllegalArgumentException if the resulting method handle's type would have

      *          <a href="MethodHandle.html#maxarity">too many parameters</a>

      */

     static public

     MethodHandle invoker(MethodType type) {

         return type.invokers().generalInvoker();

     }

     static /*non-public*/

     MethodHandle basicInvoker(MethodType type) {

         return type.form().basicInvoker();

     }

      /// method handle modification (creation from other method handles)

     /**

      * Produces a method handle which adapts the type of the

      * given method handle to a new type by pairwise argument and return type conversion.

      * The original type and new type must have the same number of arguments.

      * The resulting method handle is guaranteed to report a type

      * which is equal to the desired new type.

      * <p>

      * If the original type and new type are equal, returns target.

      * <p>

      * The same conversions are allowed as for {@link MethodHandle#asType MethodHandle.asType},

      * and some additional conversions are also applied if those conversions fail.

      * Given types <em>T0</em>, <em>T1</em>, one of the following conversions is applied

      * if possible, before or instead of any conversions done by {@code asType}:

      * <ul>

      * <li>If <em>T0</em> and <em>T1</em> are references, and <em>T1</em> is an interface type,

      *     then the value of type <em>T0</em> is passed as a <em>T1</em> without a cast.

      *     (This treatment of interfaces follows the usage of the bytecode verifier.)

      * <li>If <em>T0</em> is boolean and <em>T1</em> is another primitive,

      *     the boolean is converted to a byte value, 1 for true, 0 for false.

      *     (This treatment follows the usage of the bytecode verifier.)

      * <li>If <em>T1</em> is boolean and <em>T0</em> is another primitive,

      *     <em>T0</em> is converted to byte via Java casting conversion (JLS 5.5),

      *     and the low order bit of the result is tested, as if by {@code (x & 1) != 0}.

      * <li>If <em>T0</em> and <em>T1</em> are primitives other than boolean,

      *     then a Java casting conversion (JLS 5.5) is applied.

      *     (Specifically, <em>T0</em> will convert to <em>T1</em> by

      *     widening and/or narrowing.)

      * <li>If <em>T0</em> is a reference and <em>T1</em> a primitive, an unboxing

      *     conversion will be applied at runtime, possibly followed

      *     by a Java casting conversion (JLS 5.5) on the primitive value,

      *     possibly followed by a conversion from byte to boolean by testing

      *     the low-order bit.

      * <li>If <em>T0</em> is a reference and <em>T1</em> a primitive,

      *     and if the reference is null at runtime, a zero value is introduced.

      * </ul>

      * @param target the method handle to invoke after arguments are retyped

      * @param newType the expected type of the new method handle

      * @return a method handle which delegates to the target after performing

      *           any necessary argument conversions, and arranges for any

      *           necessary return value conversions

      * @throws NullPointerException if either argument is null

      * @throws WrongMethodTypeException if the conversion cannot be made

      * @see MethodHandle#asType

      */

     public static

     MethodHandle explicitCastArguments(MethodHandle target, MethodType newType) {

         if (!target.type().isCastableTo(newType)) {

             throw new WrongMethodTypeException("cannot explicitly cast "+target+" to "+newType);

         }

         return MethodHandleImpl.makePairwiseConvert(target, newType, 2);

     }

     /**

      * Produces a method handle which adapts the calling sequence of the

      * given method handle to a new type, by reordering the arguments.

      * The resulting method handle is guaranteed to report a type

      * which is equal to the desired new type.

      * <p>

      * The given array controls the reordering.

      * Call {@code #I} the number of incoming parameters (the value

      * {@code newType.parameterCount()}, and call {@code #O} the number

      * of outgoing parameters (the value {@code target.type().parameterCount()}).

      * Then the length of the reordering array must be {@code #O},

      * and each element must be a non-negative number less than {@code #I}.

      * For every {@code N} less than {@code #O}, the {@code N}-th

      * outgoing argument will be taken from the {@code I}-th incoming

      * argument, where {@code I} is {@code reorder[N]}.

      * <p>

      * No argument or return value conversions are applied.

      * The type of each incoming argument, as determined by {@code newType},

      * must be identical to the type of the corresponding outgoing parameter

      * or parameters in the target method handle.

      * The return type of {@code newType} must be identical to the return

      * type of the original target.

      * <p>

      * The reordering array need not specify an actual permutation.

      * An incoming argument will be duplicated if its index appears

      * more than once in the array, and an incoming argument will be dropped

      * if its index does not appear in the array.

      * As in the case of {@link #dropArguments(MethodHandle,int,List) dropArguments},

      * incoming arguments which are not mentioned in the reordering array

      * are may be any type, as determined only by {@code newType}.

      * <blockquote><pre>{@code

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

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

 ...

 MethodType intfn1 = methodType(int.class, int.class);

 MethodType intfn2 = methodType(int.class, int.class, int.class);

 MethodHandle sub = ... (int x, int y) -> (x-y) ...;

 assert(sub.type().equals(intfn2));

 MethodHandle sub1 = permuteArguments(sub, intfn2, 0, 1);

 MethodHandle rsub = permuteArguments(sub, intfn2, 1, 0);

 assert((int)rsub.invokeExact(1, 100) == 99);

 MethodHandle add = ... (int x, int y) -> (x+y) ...;

 assert(add.type().equals(intfn2));

 MethodHandle twice = permuteArguments(add, intfn1, 0, 0);

 assert(twice.type().equals(intfn1));

 assert((int)twice.invokeExact(21) == 42);

      * }</pre></blockquote>

      * @param target the method handle to invoke after arguments are reordered

      * @param newType the expected type of the new method handle

      * @param reorder an index array which controls the reordering

      * @return a method handle which delegates to the target after it

      *           drops unused arguments and moves and/or duplicates the other arguments

      * @throws NullPointerException if any argument is null

      * @throws IllegalArgumentException if the index array length is not equal to

      *                  the arity of the target, or if any index array element

      *                  not a valid index for a parameter of {@code newType},

      *                  or if two corresponding parameter types in

      *                  {@code target.type()} and {@code newType} are not identical,

      */

     public static

     MethodHandle permuteArguments(MethodHandle target, MethodType newType, int... reorder) {

         checkReorder(reorder, newType, target.type());

         return target.permuteArguments(newType, reorder);

     }

     private static void checkReorder(int[] reorder, MethodType newType, MethodType oldType) {

         if (newType.returnType() != oldType.returnType())

             throw newIllegalArgumentException("return types do not match",

                     oldType, newType);

         if (reorder.length == oldType.parameterCount()) {

             int limit = newType.parameterCount();

             boolean bad = false;

             for (int j = 0; j < reorder.length; j++) {

                 int i = reorder[j];

                 if (i < 0 || i >= limit) {

                     bad = true; break;

                 }

                 Class<?> src = newType.parameterType(i);

                 Class<?> dst = oldType.parameterType(j);

                 if (src != dst)

                     throw newIllegalArgumentException("parameter types do not match after reorder",

                             oldType, newType);

             }

             if (!bad)  return;

         }

         throw newIllegalArgumentException("bad reorder array: "+Arrays.toString(reorder));

     }

     /**

      * Produces a method handle of the requested return type which returns the given

      * constant value every time it is invoked.

      * <p>

      * Before the method handle is returned, the passed-in value is converted to the requested type.

      * If the requested type is primitive, widening primitive conversions are attempted,

      * else reference conversions are attempted.

      * <p>The returned method handle is equivalent to {@code identity(type).bindTo(value)}.

      * @param type the return type of the desired method handle

      * @param value the value to return

      * @return a method handle of the given return type and no arguments, which always returns the given value

      * @throws NullPointerException if the {@code type} argument is null

      * @throws ClassCastException if the value cannot be converted to the required return type

      * @throws IllegalArgumentException if the given type is {@code void.class}

      */

     public static

     MethodHandle constant(Class<?> type, Object value) {

         if (type.isPrimitive()) {

             if (type == void.class)

                 throw newIllegalArgumentException("void type");

             Wrapper w = Wrapper.forPrimitiveType(type);

             return insertArguments(identity(type), 0, w.convert(value, type));

         } else {

             return identity(type).bindTo(type.cast(value));

         }

     }

     /**

      * Produces a method handle which returns its sole argument when invoked.

      * @param type the type of the sole parameter and return value of the desired method handle

      * @return a unary method handle which accepts and returns the given type

      * @throws NullPointerException if the argument is null

      * @throws IllegalArgumentException if the given type is {@code void.class}

      */

     public static

     MethodHandle identity(Class<?> type) {

         if (type == void.class)

             throw newIllegalArgumentException("void type");

         else if (type == Object.class)

             return ValueConversions.identity();

         else if (type.isPrimitive())

             return ValueConversions.identity(Wrapper.forPrimitiveType(type));

         else

             return MethodHandleImpl.makeReferenceIdentity(type);

     }

     /**

      * Provides a target method handle with one or more <em>bound arguments</em>

      * in advance of the method handle's invocation.

      * The formal parameters to the target corresponding to the bound

      * arguments are called <em>bound parameters</em>.

      * Returns a new method handle which saves away the bound arguments.

      * When it is invoked, it receives arguments for any non-bound parameters,

      * binds the saved arguments to their corresponding parameters,

      * and calls the original target.

      * <p>

      * The type of the new method handle will drop the types for the bound

      * parameters from the original target type, since the new method handle

      * will no longer require those arguments to be supplied by its callers.

      * <p>

      * Each given argument object must match the corresponding bound parameter type.

      * If a bound parameter type is a primitive, the argument object

      * must be a wrapper, and will be unboxed to produce the primitive value.

      * <p>

      * The {@code pos} argument selects which parameters are to be bound.

      * It may range between zero and <i>N-L</i> (inclusively),

      * where <i>N</i> is the arity of the target method handle

      * and <i>L</i> is the length of the values array.

      * @param target the method handle to invoke after the argument is inserted

      * @param pos where to insert the argument (zero for the first)

      * @param values the series of arguments to insert

      * @return a method handle which inserts an additional argument,

      *         before calling the original method handle

      * @throws NullPointerException if the target or the {@code values} array is null

      * @see MethodHandle#bindTo

      */

     public static

     MethodHandle insertArguments(MethodHandle target, int pos, Object... values) {

         int insCount = values.length;

         MethodType oldType = target.type();

         int outargs = oldType.parameterCount();

         int inargs  = outargs - insCount;

         if (inargs < 0)

             throw newIllegalArgumentException("too many values to insert");

         if (pos < 0 || pos > inargs)

             throw newIllegalArgumentException("no argument type to append");

         MethodHandle result = target;

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

             Object value = values[i];

             Class<?> ptype = oldType.parameterType(pos+i);

             if (ptype.isPrimitive()) {

                 char btype = 'I';

                 Wrapper w = Wrapper.forPrimitiveType(ptype);

                 switch (w) {

                 case LONG:    btype = 'J'; break;

                 case FLOAT:   btype = 'F'; break;

                 case DOUBLE:  btype = 'D'; break;

                 }

                 // perform unboxing and/or primitive conversion

                 value = w.convert(value, ptype);

                 result = result.bindArgument(pos, btype, value);

                 continue;

             }

             value = ptype.cast(value);  // throw CCE if needed

             if (pos == 0) {

                 result = result.bindReceiver(value);

             } else {

                 result = result.bindArgument(pos, 'L', value);

             }

         }

         return result;

     }

     /**

      * Produces a method handle which will discard some dummy arguments

      * before calling some other specified <i>target</i> method handle.

      * The type of the new method handle will be the same as the target's type,

      * except it will also include the dummy argument types,

      * at some given position.

      * <p>

      * The {@code pos} argument may range between zero and <i>N</i>,

      * where <i>N</i> is the arity of the target.

      * If {@code pos} is zero, the dummy arguments will precede

      * the target's real arguments; if {@code pos} is <i>N</i>

      * they will come after.

      * <p>

      * <b>Example:</b>

      * <blockquote><pre>{@code

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

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

 ...

 MethodHandle cat = lookup().findVirtual(String.class,

   "concat", methodType(String.class, String.class));

 assertEquals("xy", (String) cat.invokeExact("x", "y"));

 MethodType bigType = cat.type().insertParameterTypes(0, int.class, String.class);

 MethodHandle d0 = dropArguments(cat, 0, bigType.parameterList().subList(0,2));

 assertEquals(bigType, d0.type());

 assertEquals("yz", (String) d0.invokeExact(123, "x", "y", "z"));

      * }</pre></blockquote>

      * <p>

      * This method is also equivalent to the following code:

      * <blockquote><pre>

      * {@link #dropArguments(MethodHandle,int,Class...) dropArguments}{@code (target, pos, valueTypes.toArray(new Class[0]))}

      * </pre></blockquote>

      * @param target the method handle to invoke after the arguments are dropped

      * @param valueTypes the type(s) of the argument(s) to drop

      * @param pos position of first argument to drop (zero for the leftmost)

      * @return a method handle which drops arguments of the given types,

      *         before calling the original method handle

      * @throws NullPointerException if the target is null,

      *                              or if the {@code valueTypes} list or any of its elements is null

      * @throws IllegalArgumentException if any element of {@code valueTypes} is {@code void.class},

      *                  or if {@code pos} is negative or greater than the arity of the target,

      *                  or if the new method handle's type would have too many parameters

      */

     public static

     MethodHandle dropArguments(MethodHandle target, int pos, List<Class<?>> valueTypes) {

         MethodType oldType = target.type();  // get NPE

         int dropped = valueTypes.size();

         MethodType.checkSlotCount(dropped);

         if (dropped == 0)  return target;

         int outargs = oldType.parameterCount();

         int inargs  = outargs + dropped;

         if (pos < 0 || pos >= inargs)

             throw newIllegalArgumentException("no argument type to remove");

         ArrayList<Class<?>> ptypes = new ArrayList<>(oldType.parameterList());

         ptypes.addAll(pos, valueTypes);

         MethodType newType = MethodType.methodType(oldType.returnType(), ptypes);

         return target.dropArguments(newType, pos, dropped);

     }

     /**

      * Produces a method handle which will discard some dummy arguments

      * before calling some other specified <i>target</i> method handle.

      * The type of the new method handle will be the same as the target's type,

      * except it will also include the dummy argument types,

      * at some given position.

      * <p>

      * The {@code pos} argument may range between zero and <i>N</i>,

      * where <i>N</i> is the arity of the target.

      * If {@code pos} is zero, the dummy arguments will precede

      * the target's real arguments; if {@code pos} is <i>N</i>

      * they will come after.

      * <p>

      * <b>Example:</b>

      * <blockquote><pre>{@code

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

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

 ...

 MethodHandle cat = lookup().findVirtual(String.class,

   "concat", methodType(String.class, String.class));

 assertEquals("xy", (String) cat.invokeExact("x", "y"));

 MethodHandle d0 = dropArguments(cat, 0, String.class);

 assertEquals("yz", (String) d0.invokeExact("x", "y", "z"));

 MethodHandle d1 = dropArguments(cat, 1, String.class);

 assertEquals("xz", (String) d1.invokeExact("x", "y", "z"));

 MethodHandle d2 = dropArguments(cat, 2, String.class);

 assertEquals("xy", (String) d2.invokeExact("x", "y", "z"));

 MethodHandle d12 = dropArguments(cat, 1, int.class, boolean.class);

 assertEquals("xz", (String) d12.invokeExact("x", 12, true, "z"));

      * }</pre></blockquote>

      * <p>

      * This method is also equivalent to the following code:

      * <blockquote><pre>

      * {@link #dropArguments(MethodHandle,int,List) dropArguments}{@code (target, pos, Arrays.asList(valueTypes))}

      * </pre></blockquote>

      * @param target the method handle to invoke after the arguments are dropped

      * @param valueTypes the type(s) of the argument(s) to drop

      * @param pos position of first argument to drop (zero for the leftmost)

      * @return a method handle which drops arguments of the given types,

      *         before calling the original method handle

      * @throws NullPointerException if the target is null,

      *                              or if the {@code valueTypes} array or any of its elements is null

      * @throws IllegalArgumentException if any element of {@code valueTypes} is {@code void.class},

      *                  or if {@code pos} is negative or greater than the arity of the target,

      *                  or if the new method handle's type would have

      *                  <a href="MethodHandle.html#maxarity">too many parameters</a>

      */

     public static

     MethodHandle dropArguments(MethodHandle target, int pos, Class<?>... valueTypes) {

         return dropArguments(target, pos, Arrays.asList(valueTypes));

     }

     /**

      * Adapts a target method handle by pre-processing

      * one or more of its arguments, each with its own unary filter function,

      * and then calling the target with each pre-processed argument

      * replaced by the result of its corresponding filter function.

      * <p>

      * The pre-processing is performed by one or more method handles,

      * specified in the elements of the {@code filters} array.

      * The first element of the filter array corresponds to the {@code pos}

      * argument of the target, and so on in sequence.

      * <p>

      * Null arguments in the array are treated as identity functions,

      * and the corresponding arguments left unchanged.

      * (If there are no non-null elements in the array, the original target is returned.)

      * Each filter is applied to the corresponding argument of the adapter.

      * <p>

      * If a filter {@code F} applies to the {@code N}th argument of

      * the target, then {@code F} must be a method handle which

      * takes exactly one argument.  The type of {@code F}'s sole argument

      * replaces the corresponding argument type of the target

      * in the resulting adapted method handle.

      * The return type of {@code F} must be identical to the corresponding

      * parameter type of the target.

      * <p>

      * It is an error if there are elements of {@code filters}

      * (null or not)

      * which do not correspond to argument positions in the target.

      * <p><b>Example:</b>

      * <blockquote><pre>{@code

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

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

 ...

 MethodHandle cat = lookup().findVirtual(String.class,

   "concat", methodType(String.class, String.class));

 MethodHandle upcase = lookup().findVirtual(String.class,

   "toUpperCase", methodType(String.class));

 assertEquals("xy", (String) cat.invokeExact("x", "y"));

 MethodHandle f0 = filterArguments(cat, 0, upcase);

 assertEquals("Xy", (String) f0.invokeExact("x", "y")); // Xy

 MethodHandle f1 = filterArguments(cat, 1, upcase);

 assertEquals("xY", (String) f1.invokeExact("x", "y")); // xY

 MethodHandle f2 = filterArguments(cat, 0, upcase, upcase);

 assertEquals("XY", (String) f2.invokeExact("x", "y")); // XY

      * }</pre></blockquote>

      * <p> Here is pseudocode for the resulting adapter:

      * <blockquote><pre>{@code

      * V target(P... p, A[i]... a[i], B... b);

      * A[i] filter[i](V[i]);

      * T adapter(P... p, V[i]... v[i], B... b) {

      *   return target(p..., f[i](v[i])..., b...);

      * }

      * }</pre></blockquote>

      *

      * @param target the method handle to invoke after arguments are filtered

      * @param pos the position of the first argument to filter

      * @param filters method handles to call initially on filtered arguments

      * @return method handle which incorporates the specified argument filtering logic

      * @throws NullPointerException if the target is null

      *                              or if the {@code filters} array is null

      * @throws IllegalArgumentException if a non-null element of {@code filters}

      *          does not match a corresponding argument type of target as described above,

      *          or if the {@code pos+filters.length} is greater than {@code target.type().parameterCount()},

      *          or if the resulting method handle's type would have

      *          <a href="MethodHandle.html#maxarity">too many parameters</a>

      */

     public static

     MethodHandle filterArguments(MethodHandle target, int pos, MethodHandle... filters) {

         MethodType targetType = target.type();

         MethodHandle adapter = target;

         MethodType adapterType = null;

         assert((adapterType = targetType) != null);

         int maxPos = targetType.parameterCount();

         if (pos + filters.length > maxPos)

             throw newIllegalArgumentException("too many filters");

         int curPos = pos-1;  // pre-incremented

         for (MethodHandle filter : filters) {

             curPos += 1;

             if (filter == null)  continue;  // ignore null elements of filters

             adapter = filterArgument(adapter, curPos, filter);

             assert((adapterType = adapterType.changeParameterType(curPos, filter.type().parameterType(0))) != null);

         }

         assert(adapterType.equals(adapter.type()));

         return adapter;

     }

     /*non-public*/ static

     MethodHandle filterArgument(MethodHandle target, int pos, MethodHandle filter) {

         MethodType targetType = target.type();

         MethodType filterType = filter.type();

         if (filterType.parameterCount() != 1

             || filterType.returnType() != targetType.parameterType(pos))

             throw newIllegalArgumentException("target and filter types do not match", targetType, filterType);

         return MethodHandleImpl.makeCollectArguments(target, filter, pos, false);

     }

     /**

      * Adapts a target method handle by pre-processing

      * a sub-sequence of its arguments with a filter (another method handle).

      * The pre-processed arguments are replaced by the result (if any) of the

      * filter function.

      * The target is then called on the modified (usually shortened) argument list.

      * <p>

      * If the filter returns a value, the target must accept that value as

      * its argument in position {@code pos}, preceded and/or followed by

      * any arguments not passed to the filter.

      * If the filter returns void, the target must accept all arguments

      * not passed to the filter.

      * No arguments are reordered, and a result returned from the filter

      * replaces (in order) the whole subsequence of arguments originally

      * passed to the adapter.

      * <p>

      * The argument types (if any) of the filter

      * replace zero or one argument types of the target, at position {@code pos},

      * in the resulting adapted method handle.

      * The return type of the filter (if any) must be identical to the

      * argument type of the target at position {@code pos}, and that target argument

      * is supplied by the return value of the filter.

      * <p>

      * In all cases, {@code pos} must be greater than or equal to zero, and

      * {@code pos} must also be less than or equal to the target's arity.

      * <p><b>Example:</b>

      * <blockquote><pre>{@code

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

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

 ...

 MethodHandle deepToString = publicLookup()

   .findStatic(Arrays.class, "deepToString", methodType(String.class, Object[].class));

 MethodHandle ts1 = deepToString.asCollector(String[].class, 1);

 assertEquals("[strange]", (String) ts1.invokeExact("strange"));

 MethodHandle ts2 = deepToString.asCollector(String[].class, 2);

 assertEquals("[up, down]", (String) ts2.invokeExact("up", "down"));

 MethodHandle ts3 = deepToString.asCollector(String[].class, 3);

 MethodHandle ts3_ts2 = collectArguments(ts3, 1, ts2);

 assertEquals("[top, [up, down], strange]",

              (String) ts3_ts2.invokeExact("top", "up", "down", "strange"));

 MethodHandle ts3_ts2_ts1 = collectArguments(ts3_ts2, 3, ts1);

 assertEquals("[top, [up, down], [strange]]",

              (String) ts3_ts2_ts1.invokeExact("top", "up", "down", "strange"));

 MethodHandle ts3_ts2_ts3 = collectArguments(ts3_ts2, 1, ts3);

 assertEquals("[top, [[up, down, strange], charm], bottom]",

              (String) ts3_ts2_ts3.invokeExact("top", "up", "down", "strange", "charm", "bottom"));

      * }</pre></blockquote>

      * <p> Here is pseudocode for the resulting adapter:

      * <blockquote><pre>{@code

      * T target(A...,V,C...);

      * V filter(B...);

      * T adapter(A... a,B... b,C... c) {

      *   V v = filter(b...);

      *   return target(a...,v,c...);

      * }

      * // and if the filter has no arguments:

      * T target2(A...,V,C...);

      * V filter2();

      * T adapter2(A... a,C... c) {

      *   V v = filter2();

      *   return target2(a...,v,c...);

      * }

      * // and if the filter has a void return:

      * T target3(A...,C...);

      * void filter3(B...);

      * void adapter3(A... a,B... b,C... c) {

      *   filter3(b...);

      *   return target3(a...,c...);

      * }

      * }</pre></blockquote>

      * <p>

      * A collection adapter {@code collectArguments(mh, 0, coll)} is equivalent to

      * one which first "folds" the affected arguments, and then drops them, in separate

      * steps as follows:

      * <blockquote><pre>{@code

      * mh = MethodHandles.dropArguments(mh, 1, coll.type().parameterList()); //step 2

      * mh = MethodHandles.foldArguments(mh, coll); //step 1

      * }</pre></blockquote>

      * If the target method handle consumes no arguments besides than the result

      * (if any) of the filter {@code coll}, then {@code collectArguments(mh, 0, coll)}

      * is equivalent to {@code filterReturnValue(coll, mh)}.

      * If the filter method handle {@code coll} consumes one argument and produces

      * a non-void result, then {@code collectArguments(mh, N, coll)}

      * is equivalent to {@code filterArguments(mh, N, coll)}.

      * Other equivalences are possible but would require argument permutation.

      *

      * @param target the method handle to invoke after filtering the subsequence of arguments

      * @param pos the position of the first adapter argument to pass to the filter,

      *            and/or the target argument which receives the result of the filter

      * @param filter method handle to call on the subsequence of arguments

      * @return method handle which incorporates the specified argument subsequence filtering logic

      * @throws NullPointerException if either argument is null

      * @throws IllegalArgumentException if the return type of {@code filter}

      *          is non-void and is not the same as the {@code pos} argument of the target,

      *          or if {@code pos} is not between 0 and the target's arity, inclusive,

      *          or if the resulting method handle's type would have

      *          <a href="MethodHandle.html#maxarity">too many parameters</a>

      * @see MethodHandles#foldArguments

      * @see MethodHandles#filterArguments

      * @see MethodHandles#filterReturnValue

      */

     public static

     MethodHandle collectArguments(MethodHandle target, int pos, MethodHandle filter) {

         MethodType targetType = target.type();

         MethodType filterType = filter.type();

         if (filterType.returnType() != void.class &&

             filterType.returnType() != targetType.parameterType(pos))

             throw newIllegalArgumentException("target and filter types do not match", targetType, filterType);

         return MethodHandleImpl.makeCollectArguments(target, filter, pos, false);

     }

     /**

      * Adapts a target method handle by post-processing

      * its return value (if any) with a filter (another method handle).

      * The result of the filter is returned from the adapter.

      * <p>

      * If the target returns a value, the filter must accept that value as

      * its only argument.

      * If the target returns void, the filter must accept no arguments.

      * <p>

      * The return type of the filter

      * replaces the return type of the target

      * in the resulting adapted method handle.

      * The argument type of the filter (if any) must be identical to the

      * return type of the target.

      * <p><b>Example:</b>

      * <blockquote><pre>{@code

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

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

 ...

 MethodHandle cat = lookup().findVirtual(String.class,

   "concat", methodType(String.class, String.class));

 MethodHandle length = lookup().findVirtual(String.class,

   "length", methodType(int.class));

 System.out.println((String) cat.invokeExact("x", "y")); // xy

 MethodHandle f0 = filterReturnValue(cat, length);

 System.out.println((int) f0.invokeExact("x", "y")); // 2

      * }</pre></blockquote>

      * <p> Here is pseudocode for the resulting adapter:

      * <blockquote><pre>{@code

      * V target(A...);

      * T filter(V);

      * T adapter(A... a) {

      *   V v = target(a...);

      *   return filter(v);

      * }

      * // and if the target has a void return:

      * void target2(A...);

      * T filter2();

      * T adapter2(A... a) {

      *   target2(a...);

      *   return filter2();

      * }

      * // and if the filter has a void return:

      * V target3(A...);

      * void filter3(V);

      * void adapter3(A... a) {

      *   V v = target3(a...);

      *   filter3(v);

      * }

      * }</pre></blockquote>

      * @param target the method handle to invoke before filtering the return value

      * @param filter method handle to call on the return value

      * @return method handle which incorporates the specified return value filtering logic

      * @throws NullPointerException if either argument is null

      * @throws IllegalArgumentException if the argument list of {@code filter}

      *          does not match the return type of target as described above

      */

     public static

     MethodHandle filterReturnValue(MethodHandle target, MethodHandle filter) {

         MethodType targetType = target.type();

         MethodType filterType = filter.type();

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

         int filterValues = filterType.parameterCount();

         if (filterValues == 0

                 ? (rtype != void.class)

                 : (rtype != filterType.parameterType(0)))

             throw newIllegalArgumentException("target and filter types do not match", target, filter);

         // result = fold( lambda(retval, arg...) { filter(retval) },

         //                lambda(        arg...) { target(arg...) } )

         return MethodHandleImpl.makeCollectArguments(filter, target, 0, false);

     }

     /**

      * Adapts a target method handle by pre-processing

      * some of its arguments, and then calling the target with

      * the result of the pre-processing, inserted into the original

      * sequence of arguments.

      * <p>

      * The pre-processing is performed by {@code combiner}, a second method handle.

      * Of the arguments passed to the adapter, the first {@code N} arguments

      * are copied to the combiner, which is then called.

      * (Here, {@code N} is defined as the parameter count of the combiner.)

      * After this, control passes to the target, with any result

      * from the combiner inserted before the original {@code N} incoming

      * arguments.

      * <p>

      * If the combiner returns a value, the first parameter type of the target

      * must be identical with the return type of the combiner, and the next

      * {@code N} parameter types of the target must exactly match the parameters

      * of the combiner.

      * <p>

      * If the combiner has a void return, no result will be inserted,

      * and the first {@code N} parameter types of the target

      * must exactly match the parameters of the combiner.

      * <p>

      * The resulting adapter is the same type as the target, except that the

      * first parameter type is dropped,

      * if it corresponds to the result of the combiner.

      * <p>

      * (Note that {@link #dropArguments(MethodHandle,int,List) dropArguments} can be used to remove any arguments

      * that either the combiner or the target does not wish to receive.

      * If some of the incoming arguments are destined only for the combiner,

      * consider using {@link MethodHandle#asCollector asCollector} instead, since those

      * arguments will not need to be live on the stack on entry to the

      * target.)

      * <p><b>Example:</b>

      * <blockquote><pre>{@code

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

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

 ...

 MethodHandle trace = publicLookup().findVirtual(java.io.PrintStream.class,

   "println", methodType(void.class, String.class))

     .bindTo(System.out);

 MethodHandle cat = lookup().findVirtual(String.class,

   "concat", methodType(String.class, String.class));

 assertEquals("boojum", (String) cat.invokeExact("boo", "jum"));

 MethodHandle catTrace = foldArguments(cat, trace);

 // also prints "boo":

 assertEquals("boojum", (String) catTrace.invokeExact("boo", "jum"));

      * }</pre></blockquote>

      * <p> Here is pseudocode for the resulting adapter: