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	/*
	* Copyright (c) 2008, 2016, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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	package java.lang.invoke;

	import java.lang.reflect.*;
	import java.util.BitSet;
	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 sun.reflect.CallerSensitive;
	import sun.reflect.Reflection;
	import sun.reflect.misc.ReflectUtil;
	import sun.security.util.SecurityConstants;
	import java.lang.invoke.LambdaForm.BasicType;
	import static java.lang.invoke.LambdaForm.BasicType.*;
	import static java.lang.invoke.MethodHandleStatics.*;
	import static java.lang.invoke.MethodHandleImpl.Intrinsic;
	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() {
	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 — if a method is requested but does not exist
	* <li>NoSuchFieldException — if a field is requested but does not exist
	* <li>IllegalAccessException — 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.")
	&& !name.equals("sun.reflect.ReflectionFactory"))) {
	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 {
	if (refc.isArray()) {
	throw new NoSuchMethodException("no constructor for array class: " + refc.getName());
	}
	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.bindArgumentL(0, 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.isProtected(mods) && refKind == REF_newInvokeSpecial) {
	// cannot "new" a protected ctor in a different package
	mods ^= Modifier.PROTECTED;
	}
	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, DirectMethodHandle 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);
	assert(!mh.isVarargsCollector()); // viewAsType will lose varargs-ness
	assert(mh.viewAsTypeChecks(narrowType, true));
	return mh.copyWith(narrowType, mh.form);
	}

	/** 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());

	if (refKind == REF_invokeSpecial &&
	refc != lookupClass() &&
	!refc.isInterface() &&
	refc != 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
	// and continue with the direct superclass of that class,
	// and so forth, until a match is found or no further superclasses exist.
	// FIXME: MemberName.resolve should handle this instead.
	Class<?> refcAsSuper = lookupClass();
	MemberName m2;
	do {
	refcAsSuper = refcAsSuper.getSuperclass();
	m2 = new MemberName(refcAsSuper,
	method.getName(),
	method.getMethodType(),
	REF_invokeSpecial);
	m2 = IMPL_NAMES.resolveOrNull(refKind, m2, lookupClassOrNull());
	} while (m2 == null && // no method is found yet
	refc != refcAsSuper); // search up to refc
	if (m2 == null) throw new InternalError(method.toString());
	method = m2;
	refc = refcAsSuper;
	// redo basic checks
	checkMethod(refKind, refc, method);
	}

	DirectMethodHandle dmh = DirectMethodHandle.make(refKind, refc, method);
	MethodHandle mh = dmh;
	// Optionally narrow the receiver argument to refc using restrictReceiver.
	if (doRestrict &&
	(refKind == REF_invokeSpecial \|\|
	(MethodHandleNatives.refKindHasReceiver(refKind) &&
	restrictProtectedReceiver(method)))) {
	mh = restrictReceiver(method, dmh, lookupClass());
	}
	mh = maybeBindCaller(method, mh, callerClass);
	mh = mh.setVarargs(method);
	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);
	DirectMethodHandle dmh = DirectMethodHandle.make(refc, field);
	boolean doRestrict = (MethodHandleNatives.refKindHasReceiver(refKind) &&
	restrictProtectedReceiver(field));
	if (doRestrict)
	return restrictReceiver(field, dmh, lookupClass());
	return dmh;
	}
	/** 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 newIllegalArgumentException("bad argument count", leadingArgCount);
	type = type.asSpreaderType(Object[].class, type.parameterCount() - 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().genericInvoker();
	}

	static /non-public/
	MethodHandle basicInvoker(MethodType type) {
	return type.invokers().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) {
	explicitCastArgumentsChecks(target, newType);
	// use the asTypeCache when possible:
	MethodType oldType = target.type();
	if (oldType == newType) return target;
	if (oldType.explicitCastEquivalentToAsType(newType)) {
	return target.asFixedArity().asType(newType);
	}
	return MethodHandleImpl.makePairwiseConvert(target, newType, false);
	}

	private static void explicitCastArgumentsChecks(MethodHandle target, MethodType newType) {
	if (target.type().parameterCount() != newType.parameterCount()) {
	throw new WrongMethodTypeException("cannot explicitly cast " + target + " to " + newType);
	}
	}

	/**
	* 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) {
	reorder = reorder.clone(); // get a private copy
	MethodType oldType = target.type();
	permuteArgumentChecks(reorder, newType, oldType);
	// first detect dropped arguments and handle them separately
	int[] originalReorder = reorder;
	BoundMethodHandle result = target.rebind();
	LambdaForm form = result.form;
	int newArity = newType.parameterCount();
	// Normalize the reordering into a real permutation,
	// by removing duplicates and adding dropped elements.
	// This somewhat improves lambda form caching, as well
	// as simplifying the transform by breaking it up into steps.
	for (int ddIdx; (ddIdx = findFirstDupOrDrop(reorder, newArity)) != 0; ) {
	if (ddIdx > 0) {
	// We found a duplicated entry at reorder[ddIdx].
	// Example: (x,y,z)->asList(x,y,z)
	// permuted by [1*,0,1] => (a0,a1)=>asList(a1,a0,a1)
	// permuted by [0,1,0*] => (a0,a1)=>asList(a0,a1,a0)
	// The starred element corresponds to the argument
	// deleted by the dupArgumentForm transform.
	int srcPos = ddIdx, dstPos = srcPos, dupVal = reorder[srcPos];
	boolean killFirst = false;
	for (int val; (val = reorder[--dstPos]) != dupVal; ) {
	// Set killFirst if the dup is larger than an intervening position.
	// This will remove at least one inversion from the permutation.
	if (dupVal > val) killFirst = true;
	}
	if (!killFirst) {
	srcPos = dstPos;
	dstPos = ddIdx;
	}
	form = form.editor().dupArgumentForm(1 + srcPos, 1 + dstPos);
	assert (reorder[srcPos] == reorder[dstPos]);
	oldType = oldType.dropParameterTypes(dstPos, dstPos + 1);
	// contract the reordering by removing the element at dstPos
	int tailPos = dstPos + 1;
	System.arraycopy(reorder, tailPos, reorder, dstPos, reorder.length - tailPos);
	reorder = Arrays.copyOf(reorder, reorder.length - 1);
	} else {
	int dropVal = ~ddIdx, insPos = 0;
	while (insPos < reorder.length && reorder[insPos] < dropVal) {
	// Find first element of reorder larger than dropVal.
	// This is where we will insert the dropVal.
	insPos += 1;
	}
	Class<?> ptype = newType.parameterType(dropVal);
	form = form.editor().addArgumentForm(1 + insPos, BasicType.basicType(ptype));
	oldType = oldType.insertParameterTypes(insPos, ptype);
	// expand the reordering by inserting an element at insPos
	int tailPos = insPos + 1;
	reorder = Arrays.copyOf(reorder, reorder.length + 1);
	System.arraycopy(reorder, insPos, reorder, tailPos, reorder.length - tailPos);
	reorder[insPos] = dropVal;
	}
	assert (permuteArgumentChecks(reorder, newType, oldType));
	}
	assert (reorder.length == newArity); // a perfect permutation
	// Note: This may cache too many distinct LFs. Consider backing off to varargs code.
	form = form.editor().permuteArgumentsForm(1, reorder);
	if (newType == result.type() && form == result.internalForm())
	return result;
	return result.copyWith(newType, form);
	}

	/**
	* Return an indication of any duplicate or omission in reorder.
	* If the reorder contains a duplicate entry, return the index of the second occurrence.
	* Otherwise, return ~(n), for the first n in [0..newArity-1] that is not present in reorder.
	* Otherwise, return zero.
	* If an element not in [0..newArity-1] is encountered, return reorder.length.
	*/
	private static int findFirstDupOrDrop(int[] reorder, int newArity) {
	final int BIT_LIMIT = 63; // max number of bits in bit mask
	if (newArity < BIT_LIMIT) {
	long mask = 0;
	for (int i = 0; i < reorder.length; i++) {
	int arg = reorder[i];
	if (arg >= newArity) {
	return reorder.length;
	}
	long bit = 1L << arg;
	if ((mask & bit) != 0) {
	return i; // >0 indicates a dup
	}
	mask \|= bit;
	}
	if (mask == (1L << newArity) - 1) {
	assert(Long.numberOfTrailingZeros(Long.lowestOneBit(~mask)) == newArity);
	return 0;
	}
	// find first zero
	long zeroBit = Long.lowestOneBit(~mask);
	int zeroPos = Long.numberOfTrailingZeros(zeroBit);
	assert(zeroPos <= newArity);
	if (zeroPos == newArity) {
	return 0;
	}
	return ~zeroPos;
	} else {
	// same algorithm, different bit set
	BitSet mask = new BitSet(newArity);
	for (int i = 0; i < reorder.length; i++) {
	int arg = reorder[i];
	if (arg >= newArity) {
	return reorder.length;
	}
	if (mask.get(arg)) {
	return i; // >0 indicates a dup
	}
	mask.set(arg);
	}
	int zeroPos = mask.nextClearBit(0);
	assert(zeroPos <= newArity);
	if (zeroPos == newArity) {
	return 0;
	}
	return ~zeroPos;
	}
	}

	private static boolean permuteArgumentChecks(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 true;
	}
	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);
	value = w.convert(value, type);
	if (w.zero().equals(value))
	return zero(w, type);
	return insertArguments(identity(type), 0, value);
	} else {
	if (value == null)
	return zero(Wrapper.OBJECT, type);
	return identity(type).bindTo(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) {
	Wrapper btw = (type.isPrimitive() ? Wrapper.forPrimitiveType(type) : Wrapper.OBJECT);
	int pos = btw.ordinal();
	MethodHandle ident = IDENTITY_MHS[pos];
	if (ident == null) {
	ident = setCachedMethodHandle(IDENTITY_MHS, pos, makeIdentity(btw.primitiveType()));
	}
	if (ident.type().returnType() == type)
	return ident;
	// something like identity(Foo.class); do not bother to intern these
	assert(btw == Wrapper.OBJECT);
	return makeIdentity(type);
	}
	private static final MethodHandle[] IDENTITY_MHS = new MethodHandle[Wrapper.values().length];
	private static MethodHandle makeIdentity(Class<?> ptype) {
	MethodType mtype = MethodType.methodType(ptype, ptype);
	LambdaForm lform = LambdaForm.identityForm(BasicType.basicType(ptype));
	return MethodHandleImpl.makeIntrinsic(mtype, lform, Intrinsic.IDENTITY);
	}

	private static MethodHandle zero(Wrapper btw, Class<?> rtype) {
	int pos = btw.ordinal();
	MethodHandle zero = ZERO_MHS[pos];
	if (zero == null) {
	zero = setCachedMethodHandle(ZERO_MHS, pos, makeZero(btw.primitiveType()));
	}
	if (zero.type().returnType() == rtype)
	return zero;
	assert(btw == Wrapper.OBJECT);
	return makeZero(rtype);
	}
	private static final MethodHandle[] ZERO_MHS = new MethodHandle[Wrapper.values().length];
	private static MethodHandle makeZero(Class<?> rtype) {
	MethodType mtype = MethodType.methodType(rtype);
	LambdaForm lform = LambdaForm.zeroForm(BasicType.basicType(rtype));
	return MethodHandleImpl.makeIntrinsic(mtype, lform, Intrinsic.ZERO);
	}

	synchronized private static MethodHandle setCachedMethodHandle(MethodHandle[] cache, int pos, MethodHandle value) {
	// Simulate a CAS, to avoid racy duplication of results.
	MethodHandle prev = cache[pos];
	if (prev != null) return prev;
	return cache[pos] = value;
	}

	/**
	* 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;
	Class<?>[] ptypes = insertArgumentsChecks(target, insCount, pos);
	if (insCount == 0) return target;
	BoundMethodHandle result = target.rebind();
	for (int i = 0; i < insCount; i++) {
	Object value = values[i];
	Class<?> ptype = ptypes[pos+i];
	if (ptype.isPrimitive()) {
	result = insertArgumentPrimitive(result, pos, ptype, value);
	} else {
	value = ptype.cast(value); // throw CCE if needed
	result = result.bindArgumentL(pos, value);
	}
	}
	return result;
	}

	private static BoundMethodHandle insertArgumentPrimitive(BoundMethodHandle result, int pos,
	Class<?> ptype, Object value) {
	Wrapper w = Wrapper.forPrimitiveType(ptype);
	// perform unboxing and/or primitive conversion
	value = w.convert(value, ptype);
	switch (w) {
	case INT: return result.bindArgumentI(pos, (int)value);
	case LONG: return result.bindArgumentJ(pos, (long)value);
	case FLOAT: return result.bindArgumentF(pos, (float)value);
	case DOUBLE: return result.bindArgumentD(pos, (double)value);
	default: return result.bindArgumentI(pos, ValueConversions.widenSubword(value));
	}
	}

	private static Class<?>[] insertArgumentsChecks(MethodHandle target, int insCount, int pos) throws RuntimeException {
	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");
	return oldType.ptypes();
	}

	/**
	* 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) {
	valueTypes = copyTypes(valueTypes);
	MethodType oldType = target.type(); // get NPE
	int dropped = dropArgumentChecks(oldType, pos, valueTypes);
	MethodType newType = oldType.insertParameterTypes(pos, valueTypes);
	if (dropped == 0) return target;
	BoundMethodHandle result = target.rebind();
	LambdaForm lform = result.form;
	int insertFormArg = 1 + pos;
	for (Class<?> ptype : valueTypes) {
	lform = lform.editor().addArgumentForm(insertFormArg++, BasicType.basicType(ptype));
	}
	result = result.copyWith(newType, lform);
	return result;
	}

	private static List<Class<?>> copyTypes(List<Class<?>> types) {
	Object[] a = types.toArray();
	return Arrays.asList(Arrays.copyOf(a, a.length, Class[].class));
	}

	private static int dropArgumentChecks(MethodType oldType, int pos, List<Class<?>> valueTypes) {
	int dropped = valueTypes.size();
	MethodType.checkSlotCount(dropped);
	int outargs = oldType.parameterCount();
	int inargs = outargs + dropped;
	if (pos < 0 \|\| pos > outargs)
	throw newIllegalArgumentException("no argument type to remove"
	+ Arrays.asList(oldType, pos, valueTypes, inargs, outargs)
	);
	return 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) {
	filterArgumentsCheckArity(target, pos, filters);
	MethodHandle adapter = target;
	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);
	}
	return adapter;
	}

	/non-public/ static
	MethodHandle filterArgument(MethodHandle target, int pos, MethodHandle filter) {
	filterArgumentChecks(target, pos, filter);
	MethodType targetType = target.type();
	MethodType filterType = filter.type();
	BoundMethodHandle result = target.rebind();
	Class<?> newParamType = filterType.parameterType(0);
	LambdaForm lform = result.editor().filterArgumentForm(1 + pos, BasicType.basicType(newParamType));
	MethodType newType = targetType.changeParameterType(pos, newParamType);
	result = result.copyWithExtendL(newType, lform, filter);
	return result;
	}

	private static void filterArgumentsCheckArity(MethodHandle target, int pos, MethodHandle[] filters) {
	MethodType targetType = target.type();
	int maxPos = targetType.parameterCount();
	if (pos + filters.length > maxPos)
	throw newIllegalArgumentException("too many filters");
	}

	private static void filterArgumentChecks(MethodHandle target, int pos, MethodHandle filter) throws RuntimeException {
	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);
	}

	/**
	* 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 newType = collectArgumentsChecks(target, pos, filter);
	MethodType collectorType = filter.type();
	BoundMethodHandle result = target.rebind();
	LambdaForm lform;
	if (collectorType.returnType().isArray() && filter.intrinsicName() == Intrinsic.NEW_ARRAY) {
	lform = result.editor().collectArgumentArrayForm(1 + pos, filter);
	if (lform != null) {
	return result.copyWith(newType, lform);
	}
	}
	lform = result.editor().collectArgumentsForm(1 + pos, collectorType.basicType());
	return result.copyWithExtendL(newType, lform, filter);
	}

	private static MethodType collectArgumentsChecks(MethodHandle target, int pos, MethodHandle filter) throws RuntimeException {
	MethodType targetType = target.type();
	MethodType filterType = filter.type();
	Class<?> rtype = filterType.returnType();
	List<Class<?>> filterArgs = filterType.parameterList();
	if (rtype == void.class) {
	return targetType.insertParameterTypes(pos, filterArgs);
	}
	if (rtype != targetType.parameterType(pos)) {
	throw newIllegalArgumentException("target and filter types do not match", targetType, filterType);
	}
	return targetType.dropParameterTypes(pos, pos+1).insertParameterTypes(pos, filterArgs);
	}

	/**
	* 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();
	filterReturnValueChecks(targetType, filterType);
	BoundMethodHandle result = target.rebind();
	BasicType rtype = BasicType.basicType(filterType.returnType());
	LambdaForm lform = result.editor().filterReturnForm(rtype, false);
	MethodType newType = targetType.changeReturnType(filterType.returnType());
	result = result.copyWithExtendL(newType, lform, filter);
	return result;
	}

	private static void filterReturnValueChecks(MethodType targetType, MethodType filterType) throws RuntimeException {
	Class<?> rtype = targetType.returnType();
	int filterValues = filterType.parameterCount();
	if (filterValues == 0
	? (rtype != void.class)
	: (rtype != filterType.parameterType(0) \|\| filterValues != 1))
	throw newIllegalArgumentException("target and filter types do not match", targetType, filterType);
	}

	/**
	* 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:
	* <blockquote><pre>{@code
	* // there are N arguments in A...
	* T target(V, A[N]..., B...);
	* V combiner(A...);
	* T adapter(A... a, B... b) {
	* V v = combiner(a...);
	* return target(v, a..., b...);
	* }
	* // and if the combiner has a void return:
	* T target2(A[N]..., B...);
	* void combiner2(A...);
	* T adapter2(A... a, B... b) {
	* combiner2(a...);
	* return target2(a..., b...);
	* }
	* }</pre></blockquote>
	* @param target the method handle to invoke after arguments are combined
	* @param combiner method handle to call initially on the incoming arguments
	* @return method handle which incorporates the specified argument folding logic
	* @throws NullPointerException if either argument is null
	* @throws IllegalArgumentException if {@code combiner}'s return type
	* is non-void and not the same as the first argument type of
	* the target, or if the initial {@code N} argument types
	* of the target
	* (skipping one matching the {@code combiner}'s return type)
	* are not identical with the argument types of {@code combiner}
	*/
	public static
	MethodHandle foldArguments(MethodHandle target, MethodHandle combiner) {
	int foldPos = 0;
	MethodType targetType = target.type();
	MethodType combinerType = combiner.type();
	Class<?> rtype = foldArgumentChecks(foldPos, targetType, combinerType);
	BoundMethodHandle result = target.rebind();
	boolean dropResult = (rtype == void.class);
	// Note: This may cache too many distinct LFs. Consider backing off to varargs code.
	LambdaForm lform = result.editor().foldArgumentsForm(1 + foldPos, dropResult, combinerType.basicType());
	MethodType newType = targetType;
	if (!dropResult)
	newType = newType.dropParameterTypes(foldPos, foldPos + 1);
	result = result.copyWithExtendL(newType, lform, combiner);
	return result;
	}

	private static Class<?> foldArgumentChecks(int foldPos, MethodType targetType, MethodType combinerType) {
	int foldArgs = combinerType.parameterCount();
	Class<?> rtype = combinerType.returnType();
	int foldVals = rtype == void.class ? 0 : 1;
	int afterInsertPos = foldPos + foldVals;
	boolean ok = (targetType.parameterCount() >= afterInsertPos + foldArgs);
	if (ok && !(combinerType.parameterList()
	.equals(targetType.parameterList().subList(afterInsertPos,
	afterInsertPos + foldArgs))))
	ok = false;
	if (ok && foldVals != 0 && combinerType.returnType() != targetType.parameterType(0))
	ok = false;
	if (!ok)
	throw misMatchedTypes("target and combiner types", targetType, combinerType);
	return rtype;
	}

	/**
	* Makes a method handle which adapts a target method handle,
	* by guarding it with a test, a boolean-valued method handle.
	* If the guard fails, a fallback handle is called instead.
	* All three method handles must have the same corresponding
	* argument and return types, except that the return type
	* of the test must be boolean, and the test is allowed
	* to have fewer arguments than the other two method handles.
	* <p> Here is pseudocode for the resulting adapter:
	* <blockquote><pre>{@code
	* boolean test(A...);
	* T target(A...,B...);
	* T fallback(A...,B...);
	* T adapter(A... a,B... b) {
	* if (test(a...))
	* return target(a..., b...);
	* else
	* return fallback(a..., b...);
	* }
	* }</pre></blockquote>
	* Note that the test arguments ({@code a...} in the pseudocode) cannot
	* be modified by execution of the test, and so are passed unchanged
	* from the caller to the target or fallback as appropriate.
	* @param test method handle used for test, must return boolean
	* @param target method handle to call if test passes
	* @param fallback method handle to call if test fails
	* @return method handle which incorporates the specified if/then/else logic
	* @throws NullPointerException if any argument is null
	* @throws IllegalArgumentException if {@code test} does not return boolean,
	* or if all three method types do not match (with the return
	* type of {@code test} changed to match that of the target).
	*/
	public static
	MethodHandle guardWithTest(MethodHandle test,
	MethodHandle target,
	MethodHandle fallback) {
	MethodType gtype = test.type();
	MethodType ttype = target.type();
	MethodType ftype = fallback.type();
	if (!ttype.equals(ftype))
	throw misMatchedTypes("target and fallback types", ttype, ftype);
	if (gtype.returnType() != boolean.class)
	throw newIllegalArgumentException("guard type is not a predicate "+gtype);
	List<Class<?>> targs = ttype.parameterList();
	List<Class<?>> gargs = gtype.parameterList();
	if (!targs.equals(gargs)) {
	int gpc = gargs.size(), tpc = targs.size();
	if (gpc >= tpc \|\| !targs.subList(0, gpc).equals(gargs))
	throw misMatchedTypes("target and test types", ttype, gtype);
	test = dropArguments(test, gpc, targs.subList(gpc, tpc));
	gtype = test.type();
	}
	return MethodHandleImpl.makeGuardWithTest(test, target, fallback);
	}

	static RuntimeException misMatchedTypes(String what, MethodType t1, MethodType t2) {
	return newIllegalArgumentException(what + " must match: " + t1 + " != " + t2);
	}

	/**
	* Makes a method handle which adapts a target method handle,
	* by running it inside an exception handler.
	* If the target returns normally, the adapter returns that value.
	* If an exception matching the specified type is thrown, the fallback
	* handle is called instead on the exception, plus the original arguments.
	* <p>
	* The target and handler must have the same corresponding
	* argument and return types, except that handler may omit trailing arguments
	* (similarly to the predicate in {@link #guardWithTest guardWithTest}).
	* Also, the handler must have an extra leading parameter of {@code exType} or a supertype.
	* <p> Here is pseudocode for the resulting adapter:
	* <blockquote><pre>{@code
	* T target(A..., B...);
	* T handler(ExType, A...);
	* T adapter(A... a, B... b) {
	* try {
	* return target(a..., b...);
	* } catch (ExType ex) {
	* return handler(ex, a...);
	* }
	* }
	* }</pre></blockquote>
	* Note that the saved arguments ({@code a...} in the pseudocode) cannot
	* be modified by execution of the target, and so are passed unchanged
	* from the caller to the handler, if the handler is invoked.
	* <p>
	* The target and handler must return the same type, even if the handler
	* always throws. (This might happen, for instance, because the handler
	* is simulating a {@code finally} clause).
	* To create such a throwing handler, compose the handler creation logic
	* with {@link #throwException throwException},
	* in order to create a method handle of the correct return type.
	* @param target method handle to call
	* @param exType the type of exception which the handler will catch
	* @param handler method handle to call if a matching exception is thrown
	* @return method handle which incorporates the specified try/catch logic
	* @throws NullPointerException if any argument is null
	* @throws IllegalArgumentException if {@code handler} does not accept
	* the given exception type, or if the method handle types do
	* not match in their return types and their
	* corresponding parameters
	*/
	public static
	MethodHandle catchException(MethodHandle target,
	Class<? extends Throwable> exType,
	MethodHandle handler) {
	MethodType ttype = target.type();
	MethodType htype = handler.type();
	if (htype.parameterCount() < 1 \|\|
	!htype.parameterType(0).isAssignableFrom(exType))
	throw newIllegalArgumentException("handler does not accept exception type "+exType);
	if (htype.returnType() != ttype.returnType())
	throw misMatchedTypes("target and handler return types", ttype, htype);
	List<Class<?>> targs = ttype.parameterList();
	List<Class<?>> hargs = htype.parameterList();
	hargs = hargs.subList(1, hargs.size()); // omit leading parameter from handler
	if (!targs.equals(hargs)) {
	int hpc = hargs.size(), tpc = targs.size();
	if (hpc >= tpc \|\| !targs.subList(0, hpc).equals(hargs))
	throw misMatchedTypes("target and handler types", ttype, htype);
	handler = dropArguments(handler, 1+hpc, targs.subList(hpc, tpc));
	htype = handler.type();
	}
	return MethodHandleImpl.makeGuardWithCatch(target, exType, handler);
	}

	/**
	* Produces a method handle which will throw exceptions of the given {@code exType}.
	* The method handle will accept a single argument of {@code exType},
	* and immediately throw it as an exception.
	* The method type will nominally specify a return of {@code returnType}.
	* The return type may be anything convenient: It doesn't matter to the
	* method handle's behavior, since it will never return normally.
	* @param returnType the return type of the desired method handle
	* @param exType the parameter type of the desired method handle
	* @return method handle which can throw the given exceptions
	* @throws NullPointerException if either argument is null
	*/
	public static
	MethodHandle throwException(Class<?> returnType, Class<? extends Throwable> exType) {
	if (!Throwable.class.isAssignableFrom(exType))
	throw new ClassCastException(exType.getName());
	return MethodHandleImpl.throwException(MethodType.methodType(returnType, exType));
	}
	}

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