Class Advice.AssignReturned

java.lang.Object

net.bytebuddy.asm.Advice.AssignReturned

All Implemented Interfaces:

Advice.PostProcessor

Direct Known Subclasses:

Advice.AssignReturned.ForArray, Advice.AssignReturned.ForScalar

Enclosing class:

Advice

@Enhance
public abstract static class Advice.AssignReturned
extends Object
implements Advice.PostProcessor

A post processor that uses the return value of an advice method to define values for fields, arguments, the instrumented method's return value or the exception being thrown. This post processor allows for the assignment of values from advice methods that use delegation. When inlining advice code, it is recommended to assign values directly to annotated parameters.

Assignments can either be performed by returning a single value from an advice method or by returning an array with multiple values. If the return type of an advice method is declared as an array type, the latter is assumed what can be overridden by annotating the advice method with Advice.AssignReturned.AsScalar. With a scalar assignment, the return type's default value is considered as an indication to skip any assignment what can be configured via the annotation's property. When returning null when using an array-typed assignment, the assignment will always be skipped.

Important: This post processor is not registered by default but requires explicit registration via Advice.WithCustomMapping.with(Advice.PostProcessor.Factory).

Important: Assignment exceptions will not be handled by a suppression handler but will be propagated.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static @interface	Advice.AssignReturned.AsScalar	Indicates that the advice method's return value is to be treated as a scalar value also if it is of an array type.
protected static class	Advice.AssignReturned.DefaultValueSkip	A stack manipulation that applies a null-check on the returned value which indicates if an assignment should be skipped, if discovered.
protected static class	Advice.AssignReturned.ExceptionHandler	An exception handler to handle exceptions during assignment.
static class	Advice.AssignReturned.Factory	A factory to create a Advice.AssignReturned post processor.
protected static class	Advice.AssignReturned.ForArray	A post processor implementation of Advice.AssignReturned that works on the value of an array.
protected static class	Advice.AssignReturned.ForScalar	A post processor implementation of Advice.AssignReturned that uses the returned value as such.
static interface	Advice.AssignReturned.Handler	A handler for an Advice.AssignReturned post processor to assign a value that was returned by advice to a value of the instrumented method.
static @interface	Advice.AssignReturned.ToAllArguments	Assigns the advice method's return value as an array to a number of arguments which are returned as an array where each element assigns a single value with the same index as the instrumented method's parameter.
static @interface	Advice.AssignReturned.ToArguments	Assigns the advice method's return value to an argument of the instrumented method of the given index.
static @interface	Advice.AssignReturned.ToFields	Assigns the advice method's return value to a given field.
static @interface	Advice.AssignReturned.ToReturned	Assigns the advice method's return value to the instrumented method's return value.
static @interface	Advice.AssignReturned.ToThis	Assigns the advice method's return value to the this reference of the instrumented method.
static @interface	Advice.AssignReturned.ToThrown	Assigns the advice method's return value as the instrumented method's thrown exception.

Nested classes/interfaces inherited from interface Advice.PostProcessor

Advice.PostProcessor.Compound, Advice.PostProcessor.NoOp

Field Summary

Fields

Modifier and Type	Field	Description
protected final Advice.AssignReturned.ExceptionHandler.Factory	exceptionHandlerFactory	The exception handler factory to use.
protected final boolean	exit	true if this post processor is used within exit advice.
static final int	NO_INDEX	Indicates that a value is not assigned from an array but as a scalar value.
protected final boolean	skipOnDefaultValue	true if a default value indicates that no assignment should be conducted.
protected final TypeDescription	typeDescription	The advice method's return type.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AssignReturned(TypeDescription typeDescription, Advice.AssignReturned.ExceptionHandler.Factory exceptionHandlerFactory, boolean exit, boolean skipOnDefaultValue)	Creates a new post processor for assigning an advice method's return value.

Method Summary

Modifier and Type	Method	Description
protected abstract Collection<Advice.AssignReturned.Handler>	getHandlers()	Returns a collection of all handlers to apply.
protected abstract TypeDescription	getType()	Returns the assigned type that is handled by any handler.
StackManipulation	resolve(TypeDescription instrumentedType, MethodDescription instrumentedMethod, Assigner assigner, Advice.ArgumentHandler argumentHandler, Advice.StackMapFrameHandler.ForPostProcessor stackMapFrameHandler, StackManipulation exceptionHandler)	Resolves this post processor for a given instrumented method.
protected abstract StackManipulation	toLoadInstruction(Advice.AssignReturned.Handler handler, int offset)	Creates a load instruction for the given handler.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

NO_INDEX

public static final int NO_INDEX

Indicates that a value is not assigned from an array but as a scalar value.

See Also:

• Constant Field Values

typeDescription

protected final TypeDescription typeDescription

The advice method's return type.

exceptionHandlerFactory

protected final Advice.AssignReturned.ExceptionHandler.Factory exceptionHandlerFactory

The exception handler factory to use.

exit

protected final boolean exit

true if this post processor is used within exit advice.

skipOnDefaultValue

protected final boolean skipOnDefaultValue

true if a default value indicates that no assignment should be conducted.

Constructor Details

AssignReturned

protected AssignReturned(TypeDescription typeDescription,
 Advice.AssignReturned.ExceptionHandler.Factory exceptionHandlerFactory,
 boolean exit,
 boolean skipOnDefaultValue)

Creates a new post processor for assigning an advice method's return value.

Parameters:

typeDescription - The advice method's return type.

exceptionHandlerFactory - The exception handler factory to use.

exit - true if this post processor is used within exit advice.

skipOnDefaultValue - true if a default value indicates that no assignment should be conducted.

Method Details

resolve

public StackManipulation resolve(TypeDescription instrumentedType,
 MethodDescription instrumentedMethod,
 Assigner assigner,
 Advice.ArgumentHandler argumentHandler,
 Advice.StackMapFrameHandler.ForPostProcessor stackMapFrameHandler,
 StackManipulation exceptionHandler)

Resolves this post processor for a given instrumented method.

Specified by:

resolve in interface Advice.PostProcessor

Parameters:

instrumentedType - The instrumented type.

instrumentedMethod - The instrumented method.

assigner - The assigner to use.

argumentHandler - The argument handler to use.

stackMapFrameHandler - The argument handler for the instrumented method.

exceptionHandler - The exception handler that is resolved for the instrumented method.

Returns:

The stack manipulation to apply.

getType

protected abstract TypeDescription getType()

Returns the assigned type that is handled by any handler.

Returns:

The handled type.

getHandlers

protected abstract Collection<Advice.AssignReturned.Handler> getHandlers()

Returns a collection of all handlers to apply.

Returns:

The handlers to apply.

toLoadInstruction

protected abstract StackManipulation toLoadInstruction(Advice.AssignReturned.Handler handler,
 int offset)

Creates a load instruction for the given handler.

Parameters:

handler - The handler for which to apply a load instruction.

offset - The offset of the value that is returned by the advice method.

Returns:

A stack manipulation to load the handled value.