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	/*
	* Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	package java.lang.invoke;

	import sun.invoke.util.Wrapper;

	import static sun.invoke.util.Wrapper.forPrimitiveType;
	import static sun.invoke.util.Wrapper.forWrapperType;
	import static sun.invoke.util.Wrapper.isWrapperType;

	/**
	* Abstract implementation of a lambda metafactory which provides parameter
	* unrolling and input validation.
	*
	* @see LambdaMetafactory
	*/
	/* package */ abstract class AbstractValidatingLambdaMetafactory {

	/*
	* For context, the comments for the following fields are marked in quotes
	* with their values, given this program:
	* interface II<T> { Object foo(T x); }
	* interface JJ<R extends Number> extends II<R> { }
	* class CC { String impl(int i) { return "impl:"+i; }}
	* class X {
	* public static void main(String[] args) {
	* JJ<Integer> iii = (new CC())::impl;
	* System.out.printf(">>> %s\n", iii.foo(44));
	* }}
	*/
	final Class<?> targetClass; // The class calling the meta-factory via invokedynamic "class X"
	final MethodType invokedType; // The type of the invoked method "(CC)II"
	final Class<?> samBase; // The type of the returned instance "interface JJ"
	final String samMethodName; // Name of the SAM method "foo"
	final MethodType samMethodType; // Type of the SAM method "(Object)Object"
	final MethodHandle implMethod; // Raw method handle for the implementation method
	final MethodHandleInfo implInfo; // Info about the implementation method handle "MethodHandleInfo[5 CC.impl(int)String]"
	final int implKind; // Invocation kind for implementation "5"=invokevirtual
	final boolean implIsInstanceMethod; // Is the implementation an instance method "true"
	final Class<?> implDefiningClass; // Type defining the implementation "class CC"
	final MethodType implMethodType; // Type of the implementation method "(int)String"
	final MethodType instantiatedMethodType; // Instantiated erased functional interface method type "(Integer)Object"
	final boolean isSerializable; // Should the returned instance be serializable
	final Class<?>[] markerInterfaces; // Additional marker interfaces to be implemented
	final MethodType[] additionalBridges; // Signatures of additional methods to bridge


	/**
	* Meta-factory constructor.
	*
	* @param caller Stacked automatically by VM; represents a lookup context
	* with the accessibility privileges of the caller.
	* @param invokedType Stacked automatically by VM; the signature of the
	* invoked method, which includes the expected static
	* type of the returned lambda object, and the static
	* types of the captured arguments for the lambda. In
	* the event that the implementation method is an
	* instance method, the first argument in the invocation
	* signature will correspond to the receiver.
	* @param samMethodName Name of the method in the functional interface to
	* which the lambda or method reference is being
	* converted, represented as a String.
	* @param samMethodType Type of the method in the functional interface to
	* which the lambda or method reference is being
	* converted, represented as a MethodType.
	* @param implMethod The implementation method which should be called
	* (with suitable adaptation of argument types, return
	* types, and adjustment for captured arguments) when
	* methods of the resulting functional interface instance
	* are invoked.
	* @param instantiatedMethodType The signature of the primary functional
	* interface method after type variables are
	* substituted with their instantiation from
	* the capture site
	* @param isSerializable Should the lambda be made serializable? If set,
	* either the target type or one of the additional SAM
	* types must extend {@code Serializable}.
	* @param markerInterfaces Additional interfaces which the lambda object
	* should implement.
	* @param additionalBridges Method types for additional signatures to be
	* bridged to the implementation method
	* @throws LambdaConversionException If any of the meta-factory protocol
	* invariants are violated
	*/
	AbstractValidatingLambdaMetafactory(MethodHandles.Lookup caller,
	MethodType invokedType,
	String samMethodName,
	MethodType samMethodType,
	MethodHandle implMethod,
	MethodType instantiatedMethodType,
	boolean isSerializable,
	Class<?>[] markerInterfaces,
	MethodType[] additionalBridges)
	throws LambdaConversionException {
	if ((caller.lookupModes() & MethodHandles.Lookup.PRIVATE) == 0) {
	throw new LambdaConversionException(String.format(
	"Invalid caller: %s",
	caller.lookupClass().getName()));
	}
	this.targetClass = caller.lookupClass();
	this.invokedType = invokedType;

	this.samBase = invokedType.returnType();

	this.samMethodName = samMethodName;
	this.samMethodType = samMethodType;

	this.implMethod = implMethod;
	this.implInfo = caller.revealDirect(implMethod);
	this.implKind = implInfo.getReferenceKind();
	this.implIsInstanceMethod =
	implKind == MethodHandleInfo.REF_invokeVirtual \|\|
	implKind == MethodHandleInfo.REF_invokeSpecial \|\|
	implKind == MethodHandleInfo.REF_invokeInterface;
	this.implDefiningClass = implInfo.getDeclaringClass();
	this.implMethodType = implInfo.getMethodType();
	this.instantiatedMethodType = instantiatedMethodType;
	this.isSerializable = isSerializable;
	this.markerInterfaces = markerInterfaces;
	this.additionalBridges = additionalBridges;

	if (!samBase.isInterface()) {
	throw new LambdaConversionException(String.format(
	"Functional interface %s is not an interface",
	samBase.getName()));
	}

	for (Class<?> c : markerInterfaces) {
	if (!c.isInterface()) {
	throw new LambdaConversionException(String.format(
	"Marker interface %s is not an interface",
	c.getName()));
	}
	}
	}

	/**
	* Build the CallSite.
	*
	* @return a CallSite, which, when invoked, will return an instance of the
	* functional interface
	* @throws ReflectiveOperationException
	*/
	abstract CallSite buildCallSite()
	throws LambdaConversionException;

	/**
	* Check the meta-factory arguments for errors
	* @throws LambdaConversionException if there are improper conversions
	*/
	void validateMetafactoryArgs() throws LambdaConversionException {
	switch (implKind) {
	case MethodHandleInfo.REF_invokeInterface:
	case MethodHandleInfo.REF_invokeVirtual:
	case MethodHandleInfo.REF_invokeStatic:
	case MethodHandleInfo.REF_newInvokeSpecial:
	case MethodHandleInfo.REF_invokeSpecial:
	break;
	default:
	throw new LambdaConversionException(String.format("Unsupported MethodHandle kind: %s", implInfo));
	}

	// Check arity: optional-receiver + captured + SAM == impl
	final int implArity = implMethodType.parameterCount();
	final int receiverArity = implIsInstanceMethod ? 1 : 0;
	final int capturedArity = invokedType.parameterCount();
	final int samArity = samMethodType.parameterCount();
	final int instantiatedArity = instantiatedMethodType.parameterCount();
	if (implArity + receiverArity != capturedArity + samArity) {
	throw new LambdaConversionException(
	String.format("Incorrect number of parameters for %s method %s; %d captured parameters, %d functional interface method parameters, %d implementation parameters",
	implIsInstanceMethod ? "instance" : "static", implInfo,
	capturedArity, samArity, implArity));
	}
	if (instantiatedArity != samArity) {
	throw new LambdaConversionException(
	String.format("Incorrect number of parameters for %s method %s; %d instantiated parameters, %d functional interface method parameters",
	implIsInstanceMethod ? "instance" : "static", implInfo,
	instantiatedArity, samArity));
	}
	for (MethodType bridgeMT : additionalBridges) {
	if (bridgeMT.parameterCount() != samArity) {
	throw new LambdaConversionException(
	String.format("Incorrect number of parameters for bridge signature %s; incompatible with %s",
	bridgeMT, samMethodType));
	}
	}

	// If instance: first captured arg (receiver) must be subtype of class where impl method is defined
	final int capturedStart;
	final int samStart;
	if (implIsInstanceMethod) {
	final Class<?> receiverClass;

	// implementation is an instance method, adjust for receiver in captured variables / SAM arguments
	if (capturedArity == 0) {
	// receiver is function parameter
	capturedStart = 0;
	samStart = 1;
	receiverClass = instantiatedMethodType.parameterType(0);
	} else {
	// receiver is a captured variable
	capturedStart = 1;
	samStart = 0;
	receiverClass = invokedType.parameterType(0);
	}

	// check receiver type
	if (!implDefiningClass.isAssignableFrom(receiverClass)) {
	throw new LambdaConversionException(
	String.format("Invalid receiver type %s; not a subtype of implementation type %s",
	receiverClass, implDefiningClass));
	}

	Class<?> implReceiverClass = implMethod.type().parameterType(0);
	if (implReceiverClass != implDefiningClass && !implReceiverClass.isAssignableFrom(receiverClass)) {
	throw new LambdaConversionException(
	String.format("Invalid receiver type %s; not a subtype of implementation receiver type %s",
	receiverClass, implReceiverClass));
	}
	} else {
	// no receiver
	capturedStart = 0;
	samStart = 0;
	}

	// Check for exact match on non-receiver captured arguments
	final int implFromCaptured = capturedArity - capturedStart;
	for (int i=0; i<implFromCaptured; i++) {
	Class<?> implParamType = implMethodType.parameterType(i);
	Class<?> capturedParamType = invokedType.parameterType(i + capturedStart);
	if (!capturedParamType.equals(implParamType)) {
	throw new LambdaConversionException(
	String.format("Type mismatch in captured lambda parameter %d: expecting %s, found %s",
	i, capturedParamType, implParamType));
	}
	}
	// Check for adaptation match on SAM arguments
	final int samOffset = samStart - implFromCaptured;
	for (int i=implFromCaptured; i<implArity; i++) {
	Class<?> implParamType = implMethodType.parameterType(i);
	Class<?> instantiatedParamType = instantiatedMethodType.parameterType(i + samOffset);
	if (!isAdaptableTo(instantiatedParamType, implParamType, true)) {
	throw new LambdaConversionException(
	String.format("Type mismatch for lambda argument %d: %s is not convertible to %s",
	i, instantiatedParamType, implParamType));
	}
	}

	// Adaptation match: return type
	Class<?> expectedType = instantiatedMethodType.returnType();
	Class<?> actualReturnType =
	(implKind == MethodHandleInfo.REF_newInvokeSpecial)
	? implDefiningClass
	: implMethodType.returnType();
	Class<?> samReturnType = samMethodType.returnType();
	if (!isAdaptableToAsReturn(actualReturnType, expectedType)) {
	throw new LambdaConversionException(
	String.format("Type mismatch for lambda return: %s is not convertible to %s",
	actualReturnType, expectedType));
	}
	if (!isAdaptableToAsReturnStrict(expectedType, samReturnType)) {
	throw new LambdaConversionException(
	String.format("Type mismatch for lambda expected return: %s is not convertible to %s",
	expectedType, samReturnType));
	}
	for (MethodType bridgeMT : additionalBridges) {
	if (!isAdaptableToAsReturnStrict(expectedType, bridgeMT.returnType())) {
	throw new LambdaConversionException(
	String.format("Type mismatch for lambda expected return: %s is not convertible to %s",
	expectedType, bridgeMT.returnType()));
	}
	}
	}

	/**
	* Check type adaptability for parameter types.
	* @param fromType Type to convert from
	* @param toType Type to convert to
	* @param strict If true, do strict checks, else allow that fromType may be parameterized
	* @return True if 'fromType' can be passed to an argument of 'toType'
	*/
	private boolean isAdaptableTo(Class<?> fromType, Class<?> toType, boolean strict) {
	if (fromType.equals(toType)) {
	return true;
	}
	if (fromType.isPrimitive()) {
	Wrapper wfrom = forPrimitiveType(fromType);
	if (toType.isPrimitive()) {
	// both are primitive: widening
	Wrapper wto = forPrimitiveType(toType);
	return wto.isConvertibleFrom(wfrom);
	} else {
	// from primitive to reference: boxing
	return toType.isAssignableFrom(wfrom.wrapperType());
	}
	} else {
	if (toType.isPrimitive()) {
	// from reference to primitive: unboxing
	Wrapper wfrom;
	if (isWrapperType(fromType) && (wfrom = forWrapperType(fromType)).primitiveType().isPrimitive()) {
	// fromType is a primitive wrapper; unbox+widen
	Wrapper wto = forPrimitiveType(toType);
	return wto.isConvertibleFrom(wfrom);
	} else {
	// must be convertible to primitive
	return !strict;
	}
	} else {
	// both are reference types: fromType should be a superclass of toType.
	return !strict \|\| toType.isAssignableFrom(fromType);
	}
	}
	}

	/**
	* Check type adaptability for return types --
	* special handling of void type) and parameterized fromType
	* @return True if 'fromType' can be converted to 'toType'
	*/
	private boolean isAdaptableToAsReturn(Class<?> fromType, Class<?> toType) {
	return toType.equals(void.class)
	\|\| !fromType.equals(void.class) && isAdaptableTo(fromType, toType, false);
	}
	private boolean isAdaptableToAsReturnStrict(Class<?> fromType, Class<?> toType) {
	if (fromType.equals(void.class)) return toType.equals(void.class);
	return isAdaptableTo(fromType, toType, true);
	}


	/*********** Logging support -- for debugging only, uncomment as needed
	static final Executor logPool = Executors.newSingleThreadExecutor();
	protected static void log(final String s) {
	MethodHandleProxyLambdaMetafactory.logPool.execute(new Runnable() {
	@Override
	public void run() {
	System.out.println(s);
	}
	});
	}

	protected static void log(final String s, final Throwable e) {
	MethodHandleProxyLambdaMetafactory.logPool.execute(new Runnable() {
	@Override
	public void run() {
	System.out.println(s);
	e.printStackTrace(System.out);
	}
	});
	}
	***********************/

	}

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