java/11 : java.base/java/lang/invoke/SerializedLambda.java

SerializedLambda
https://openjdk.java.net/
GPLv2 + Classpath Exception
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
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 * accompanied this code).
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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package java.lang.invoke;

import java.io.Serializable;
import java.lang.reflect.Method;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.Objects;

Serialized form of a lambda expression.  The properties of this class
represent the information that is present at the lambda factory site, including
static metafactory arguments such as the identity of the primary functional
interface method and the identity of the implementation method, as well as
dynamic metafactory arguments such as values captured from the lexical scope
at the time of lambda capture.
Implementors of serializable lambdas, such as compilers or language runtime libraries, are expected to ensure that instances deserialize properly. One means to do so is to ensure that the writeReplace method returns an instance of SerializedLambda, rather than allowing default serialization to proceed. 
SerializedLambda has a readResolve method that looks for a (possibly private) static method called $deserializeLambda$(SerializedLambda) in the capturing class, invokes that with itself as the first argument, and returns the result. Lambda classes implementing $deserializeLambda$ are responsible for validating that the properties of the SerializedLambda are consistent with a lambda actually captured by that class. 
The identity of a function object produced by deserializing the serialized form is unpredictable, and therefore identity-sensitive operations (such as reference equality, object locking, and System.identityHashCode() may produce different results in different implementations, or even upon different deserializations in the same implementation. 
See Also: LambdaMetafactory
Since: 1.8/**
 * Serialized form of a lambda expression.  The properties of this class
 * represent the information that is present at the lambda factory site, including
 * static metafactory arguments such as the identity of the primary functional
 * interface method and the identity of the implementation method, as well as
 * dynamic metafactory arguments such as values captured from the lexical scope
 * at the time of lambda capture.
 *
 * <p>Implementors of serializable lambdas, such as compilers or language
 * runtime libraries, are expected to ensure that instances deserialize properly.
 * One means to do so is to ensure that the {@code writeReplace} method returns
 * an instance of {@code SerializedLambda}, rather than allowing default
 * serialization to proceed.
 *
 * <p>{@code SerializedLambda} has a {@code readResolve} method that looks for
 * a (possibly private) static method called
 * {@code $deserializeLambda$(SerializedLambda)} in the capturing class, invokes
 * that with itself as the first argument, and returns the result.  Lambda classes
 * implementing {@code $deserializeLambda$} are responsible for validating
 * that the properties of the {@code SerializedLambda} are consistent with a
 * lambda actually captured by that class.
 *
 * <p>The identity of a function object produced by deserializing the serialized
 * form is unpredictable, and therefore identity-sensitive operations (such as
 * reference equality, object locking, and {@code System.identityHashCode()} may
 * produce different results in different implementations, or even upon
 * different deserializations in the same implementation.
 *
 * @see LambdaMetafactory
 * @since 1.8
 */
public final class SerializedLambda implements Serializable {
    private static final long serialVersionUID = 8025925345765570181L;
    private final Class<?> capturingClass;
    private final String functionalInterfaceClass;
    private final String functionalInterfaceMethodName;
    private final String functionalInterfaceMethodSignature;
    private final String implClass;
    private final String implMethodName;
    private final String implMethodSignature;
    private final int implMethodKind;
    private final String instantiatedMethodType;
    private final Object[] capturedArgs;

    Create a SerializedLambda from the low-level information present at the lambda factory site. 
Params: capturingClass – The class in which the lambda expression appears
functionalInterfaceClass – Name, in slash-delimited form, of static
                                type of the returned lambda object
functionalInterfaceMethodName – Name of the functional interface
                                     method for the present at the
                                     lambda factory site
functionalInterfaceMethodSignature – Signature of the functional
                                          interface method present at
                                          the lambda factory site
implMethodKind – Method handle kind for the implementation method
implClass – Name, in slash-delimited form, for the class holding
                 the implementation method
implMethodName – Name of the implementation method
implMethodSignature – Signature of the implementation method
instantiatedMethodType – The signature of the primary functional
                              interface method after type variables
                              are substituted with their instantiation
                              from the capture site
capturedArgs – The dynamic arguments to the lambda factory site,
                    which represent variables captured by
                    the lambda/**
     * Create a {@code SerializedLambda} from the low-level information present
     * at the lambda factory site.
     *
     * @param capturingClass The class in which the lambda expression appears
     * @param functionalInterfaceClass Name, in slash-delimited form, of static
     *                                 type of the returned lambda object
     * @param functionalInterfaceMethodName Name of the functional interface
     *                                      method for the present at the
     *                                      lambda factory site
     * @param functionalInterfaceMethodSignature Signature of the functional
     *                                           interface method present at
     *                                           the lambda factory site
     * @param implMethodKind Method handle kind for the implementation method
     * @param implClass Name, in slash-delimited form, for the class holding
     *                  the implementation method
     * @param implMethodName Name of the implementation method
     * @param implMethodSignature Signature of the implementation method
     * @param instantiatedMethodType The signature of the primary functional
     *                               interface method after type variables
     *                               are substituted with their instantiation
     *                               from the capture site
     * @param capturedArgs The dynamic arguments to the lambda factory site,
     *                     which represent variables captured by
     *                     the lambda
     */
    public SerializedLambda(Class<?> capturingClass,
                            String functionalInterfaceClass,
                            String functionalInterfaceMethodName,
                            String functionalInterfaceMethodSignature,
                            int implMethodKind,
                            String implClass,
                            String implMethodName,
                            String implMethodSignature,
                            String instantiatedMethodType,
                            Object[] capturedArgs) {
        this.capturingClass = capturingClass;
        this.functionalInterfaceClass = functionalInterfaceClass;
        this.functionalInterfaceMethodName = functionalInterfaceMethodName;
        this.functionalInterfaceMethodSignature = functionalInterfaceMethodSignature;
        this.implMethodKind = implMethodKind;
        this.implClass = implClass;
        this.implMethodName = implMethodName;
        this.implMethodSignature = implMethodSignature;
        this.instantiatedMethodType = instantiatedMethodType;
        this.capturedArgs = Objects.requireNonNull(capturedArgs).clone();
    }

    Get the name of the class that captured this lambda.
Returns: the name of the class that captured this lambda/**
     * Get the name of the class that captured this lambda.
     * @return the name of the class that captured this lambda
     */
    public String getCapturingClass() {
        return capturingClass.getName().replace('.', '/');
    }

    Get the name of the invoked type to which this
lambda has been converted
Returns: the name of the functional interface class to which
this lambda has been converted/**
     * Get the name of the invoked type to which this
     * lambda has been converted
     * @return the name of the functional interface class to which
     * this lambda has been converted
     */
    public String getFunctionalInterfaceClass() {
        return functionalInterfaceClass;
    }

    Get the name of the primary method for the functional interface
to which this lambda has been converted.
Returns: the name of the primary methods of the functional interface/**
     * Get the name of the primary method for the functional interface
     * to which this lambda has been converted.
     * @return the name of the primary methods of the functional interface
     */
    public String getFunctionalInterfaceMethodName() {
        return functionalInterfaceMethodName;
    }

    Get the signature of the primary method for the functional
interface to which this lambda has been converted.
Returns: the signature of the primary method of the functional
interface/**
     * Get the signature of the primary method for the functional
     * interface to which this lambda has been converted.
     * @return the signature of the primary method of the functional
     * interface
     */
    public String getFunctionalInterfaceMethodSignature() {
        return functionalInterfaceMethodSignature;
    }

    Get the name of the class containing the implementation
method.
Returns: the name of the class containing the implementation
method/**
     * Get the name of the class containing the implementation
     * method.
     * @return the name of the class containing the implementation
     * method
     */
    public String getImplClass() {
        return implClass;
    }

    Get the name of the implementation method.
Returns: the name of the implementation method/**
     * Get the name of the implementation method.
     * @return the name of the implementation method
     */
    public String getImplMethodName() {
        return implMethodName;
    }

    Get the signature of the implementation method.
Returns: the signature of the implementation method/**
     * Get the signature of the implementation method.
     * @return the signature of the implementation method
     */
    public String getImplMethodSignature() {
        return implMethodSignature;
    }

    Get the method handle kind (see MethodHandleInfo) of the implementation method. 
Returns: the method handle kind of the implementation method/**
     * Get the method handle kind (see {@link MethodHandleInfo}) of
     * the implementation method.
     * @return the method handle kind of the implementation method
     */
    public int getImplMethodKind() {
        return implMethodKind;
    }

    Get the signature of the primary functional interface method
after type variables are substituted with their instantiation
from the capture site.
Returns: the signature of the primary functional interface method
after type variable processing/**
     * Get the signature of the primary functional interface method
     * after type variables are substituted with their instantiation
     * from the capture site.
     * @return the signature of the primary functional interface method
     * after type variable processing
     */
    public final String getInstantiatedMethodType() {
        return instantiatedMethodType;
    }

    Get the count of dynamic arguments to the lambda capture site.
Returns: the count of dynamic arguments to the lambda capture site/**
     * Get the count of dynamic arguments to the lambda capture site.
     * @return the count of dynamic arguments to the lambda capture site
     */
    public int getCapturedArgCount() {
        return capturedArgs.length;
    }

    Get a dynamic argument to the lambda capture site.
Params: i – the argument to capture
Returns: a dynamic argument to the lambda capture site/**
     * Get a dynamic argument to the lambda capture site.
     * @param i the argument to capture
     * @return a dynamic argument to the lambda capture site
     */
    public Object getCapturedArg(int i) {
        return capturedArgs[i];
    }

    private Object readResolve() throws ReflectiveOperationException {
        try {
            Method deserialize = AccessController.doPrivileged(new PrivilegedExceptionAction<>() {
                @Override
                public Method run() throws Exception {
                    Method m = capturingClass.getDeclaredMethod("$deserializeLambda$", SerializedLambda.class);
                    m.setAccessible(true);
                    return m;
                }
            });

            return deserialize.invoke(null, this);
        }
        catch (PrivilegedActionException e) {
            Exception cause = e.getException();
            if (cause instanceof ReflectiveOperationException)
                throw (ReflectiveOperationException) cause;
            else if (cause instanceof RuntimeException)
                throw (RuntimeException) cause;
            else
                throw new RuntimeException("Exception in SerializedLambda.readResolve", e);
        }
    }

    @Override
    public String toString() {
        String implKind=MethodHandleInfo.referenceKindToString(implMethodKind);
        return String.format("SerializedLambda[%s=%s, %s=%s.%s:%s, " +
                             "%s=%s %s.%s:%s, %s=%s, %s=%d]",
                             "capturingClass", capturingClass,
                             "functionalInterfaceMethod", functionalInterfaceClass,
                               functionalInterfaceMethodName,
                               functionalInterfaceMethodSignature,
                             "implementation",
                               implKind,
                               implClass, implMethodName, implMethodSignature,
                             "instantiatedMethodType", instantiatedMethodType,
                             "numCaptured", capturedArgs.length);
    }
}
Params:	i – the argument to capture
Returns:	a dynamic argument to the lambda capture site
/

java/ 11/ java.base/java/lang/invoke/SerializedLambda.java
