/*
* Copyright (c) 2012, 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 java.io.Serializable;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import sun.invoke.util.Wrapper;
import static sun.invoke.util.Wrapper.*;
/**
* 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 MethodHandle samMethod; // Raw method handle for the functional interface method
final MethodHandleInfo samInfo; // Info about the SAM method handle "MethodHandleInfo[9 II.foo(Object)Object]"
final Class<?> samClass; // Interface containing the SAM method "interface II"
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
/**
* 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 samMethod The primary method in the functional interface to which the lambda or method reference is
* being converted, represented as a method handle.
* @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
* @throws ReflectiveOperationException
* @throws LambdaConversionException If any of the meta-factory protocol invariants are violated
*/
AbstractValidatingLambdaMetafactory(MethodHandles.Lookup caller,
MethodType invokedType,
MethodHandle samMethod,
MethodHandle implMethod,
MethodType instantiatedMethodType,
int flags,
Class<?>[] markerInterfaces)
throws ReflectiveOperationException, LambdaConversionException {
this.targetClass = caller.lookupClass();
this.invokedType = invokedType;
this.samBase = invokedType.returnType();
this.samMethod = samMethod;
this.samInfo = new MethodHandleInfo(samMethod);
this.samClass = samInfo.getDeclaringClass();
this.samMethodType = samInfo.getMethodType();
this.implMethod = implMethod;
this.implInfo = new MethodHandleInfo(implMethod);
// @@@ Temporary work-around pending resolution of 8005119
this.implKind = (implInfo.getReferenceKind() == MethodHandleInfo.REF_invokeSpecial)
? MethodHandleInfo.REF_invokeVirtual
: 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;
if (!samClass.isInterface()) {
throw new LambdaConversionException(String.format(
"Functional interface %s is not an interface",
samClass.getName()));
}
boolean foundSerializableSupertype = Serializable.class.isAssignableFrom(samBase);
for (Class<?> c : markerInterfaces) {
if (!c.isInterface()) {
throw new LambdaConversionException(String.format(
"Marker interface %s is not an interface",
c.getName()));
}
foundSerializableSupertype |= Serializable.class.isAssignableFrom(c);
}
this.isSerializable = ((flags & LambdaMetafactory.FLAG_SERIALIZABLE) != 0)
|| foundSerializableSupertype;
if (isSerializable && !foundSerializableSupertype) {
markerInterfaces = Arrays.copyOf(markerInterfaces, markerInterfaces.length + 1);
markerInterfaces[markerInterfaces.length-1] = Serializable.class;
}
this.markerInterfaces = markerInterfaces;
}
/**
* Build the CallSite.
*
* @return a CallSite, which, when invoked, will return an instance of the
* functional interface
* @throws ReflectiveOperationException
*/
abstract CallSite buildCallSite() throws ReflectiveOperationException, LambdaConversionException;
/**
* Check the meta-factory arguments for errors
* @throws LambdaConversionException if there are improper conversions
*/
void validateMetafactoryArgs() throws LambdaConversionException {
// Check target type is a subtype of class where SAM method is defined
if (!samClass.isAssignableFrom(samBase)) {
throw new LambdaConversionException(
String.format("Invalid target type %s for lambda conversion; not a subtype of functional interface %s",
samBase.getName(), samClass.getName()));
}
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));
}
// 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));
}
} 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();
if (!isAdaptableToAsReturn(actualReturnType, expectedType)) {
throw new LambdaConversionException(
String.format("Type mismatch for lambda return: %s is not convertible to %s",
actualReturnType, expectedType));
}
}
/**
* Check type adaptability
* @param fromType
* @param toType
* @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) : true;
}
}
}
/**
* Check type adaptability for return types -- special handling of void type) and parameterized fromType
* @param fromType
* @param toType
* @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);
}
/*********** 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);
}
});
}
***********************/
/**
* Find the functional interface method and corresponding abstract methods
* which should be bridged. The functional interface method and those to be
* bridged will have the same name and number of parameters. Check for
* matching default methods (non-abstract), the VM will create bridges for
* default methods; We don't have enough readily available type information
* to distinguish between where the functional interface method should be
* bridged and where the default method should be bridged; This situation is
* flagged.
*/
class MethodAnalyzer {
private final Method[] methods = samBase.getMethods();
private Method samMethod = null;
private final List<Method> methodsToBridge = new ArrayList<>(methods.length);
private boolean conflictFoundBetweenDefaultAndBridge = false;
MethodAnalyzer() {
String samMethodName = samInfo.getName();
Class<?>[] samParamTypes = samMethodType.parameterArray();
int samParamLength = samParamTypes.length;
Class<?> samReturnType = samMethodType.returnType();
Class<?> objectClass = Object.class;
List<Method> defaultMethods = new ArrayList<>(methods.length);
for (Method m : methods) {
if (m.getName().equals(samMethodName) && m.getDeclaringClass() != objectClass) {
Class<?>[] mParamTypes = m.getParameterTypes();
if (mParamTypes.length == samParamLength) {
// Method matches name and parameter length -- and is not Object
if (Modifier.isAbstract(m.getModifiers())) {
// Method is abstract
if (m.getReturnType().equals(samReturnType)
&& Arrays.equals(mParamTypes, samParamTypes)) {
// Exact match, this is the SAM method signature
samMethod = m;
} else if (!hasMatchingBridgeSignature(m)) {
// Record bridges, exclude methods with duplicate signatures
methodsToBridge.add(m);
}
} else {
// Record default methods for conflict testing
defaultMethods.add(m);
}
}
}
}
for (Method dm : defaultMethods) {
if (hasMatchingBridgeSignature(dm)) {
conflictFoundBetweenDefaultAndBridge = true;
break;
}
}
}
Method getSamMethod() {
return samMethod;
}
List<Method> getMethodsToBridge() {
return methodsToBridge;
}
boolean conflictFoundBetweenDefaultAndBridge() {
return conflictFoundBetweenDefaultAndBridge;
}
/**
* Search the list of previously found bridge methods to determine if there is a method with the same signature
* (return and parameter types) as the specified method.
*
* @param m The method to match
* @return True if the method was found, False otherwise
*/
private boolean hasMatchingBridgeSignature(Method m) {
Class<?>[] ptypes = m.getParameterTypes();
Class<?> rtype = m.getReturnType();
for (Method md : methodsToBridge) {
if (md.getReturnType().equals(rtype) && Arrays.equals(ptypes, md.getParameterTypes())) {
return true;
}
}
return false;
}
}
}