org.kohsuke.nomoretears

Class Linker

java.lang.Object

org.kohsuke.nomoretears.Linker

Direct Known Subclasses:

DefaultLinker

public abstract class Linker
extends Object

Performs the linking.

The idea of a linker is as follows: normally, java compiler determines the exact method/field that are referenced in the compiled source code, and at runtime, the said method/field must exist in its exact signature. no-more-tears relaxes this constraint. At compile time, the exact signature is computed just like before, but at runtime, Linker instances get to choose the actual method/field that are linked, based on the signature information calculated at the compile time.

This is handy for example to modular systems where the version of the library used for the compilation and the version of the library used at runtime is different. In such environment, the method/field of the exact same signature might not exist, but a lax "linker" can pick up other methods/fields that superseded the original one. (Such as resolving "X Foo.getX()" to "X2 Foo.getX()" provided that X2 extends from X.)

To register a linker, add an instance to LINKERS. This list by default contains the default linker, which tries to link to the method/field of the exact signature. Normally, you should insert your linkers after this default linker.

Different call back method is provided for each kind of operation that the no-more-tears can defer the linking. The meaning of the parameters is as follows:

caller

Provide information about the call site that requires linking. MethodHandles.Lookup.lookupClass() in particular.

methodName/fieldName

Name of the method/field specified in the original code to link to. Equivalent of Member.getName()

signature

Signature of the method that was specified in the original code before it was modified by no-more-tears.

fieldType

Type of the field in the original code.

owner

Class that the method/field is supposed to belong to.

In any of the method, return null to let the other linkers attempt at linking. The first one that returns a non-null method will determine the final outcome of the link.

Author:

Kohsuke Kawaguchi

Field Summary

Fields

Modifier and Type	Field and Description
static List<Linker>	LINKERS Registered linkers that get consulted.

Constructor Summary

Constructors

Constructor and Description
Linker()

Method Summary

Methods

Modifier and Type	Method and Description
abstract CallSite	getField(MethodHandles.Lookup caller, String fieldName, Class<?> fieldType, Class<?> owner)
abstract CallSite	getStatic(MethodHandles.Lookup caller, String fieldName, Class<?> fieldType, Class<?> owner)
abstract CallSite	invokeConstructor(MethodHandles.Lookup caller, MethodType signature, Class<?> owner)
abstract CallSite	invokeInterface(MethodHandles.Lookup caller, String methodName, MethodType signature, Class<?> owner)
abstract CallSite	invokeSpecial(MethodHandles.Lookup caller, String methodName, MethodType signature, Class<?> owner)
abstract CallSite	invokeStatic(MethodHandles.Lookup caller, String methodName, MethodType signature, Class<?> owner)
abstract CallSite	invokeVirtual(MethodHandles.Lookup caller, String methodName, MethodType signature, Class<?> owner)
abstract CallSite	putField(MethodHandles.Lookup caller, String fieldName, Class<?> fieldType, Class<?> owner)
abstract CallSite	putStatic(MethodHandles.Lookup caller, String fieldName, Class<?> fieldType, Class<?> owner)
void	register()
void	unregister()

Methods inherited from class java.lang.Object

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

Field Detail

LINKERS

public static List<Linker> LINKERS

Registered linkers that get consulted.

Constructor Detail

Linker

public Linker()

Method Detail

invokeVirtual

public abstract CallSite invokeVirtual(MethodHandles.Lookup caller,
                     String methodName,
                     MethodType signature,
                     Class<?> owner)
                                throws ReflectiveOperationException

Throws:

ReflectiveOperationException

invokeStatic

public abstract CallSite invokeStatic(MethodHandles.Lookup caller,
                    String methodName,
                    MethodType signature,
                    Class<?> owner)
                               throws ReflectiveOperationException

Throws:

ReflectiveOperationException

invokeInterface

public abstract CallSite invokeInterface(MethodHandles.Lookup caller,
                       String methodName,
                       MethodType signature,
                       Class<?> owner)
                                  throws ReflectiveOperationException

Throws:

ReflectiveOperationException

invokeSpecial

public abstract CallSite invokeSpecial(MethodHandles.Lookup caller,
                     String methodName,
                     MethodType signature,
                     Class<?> owner)
                                throws ReflectiveOperationException

Throws:

ReflectiveOperationException

invokeConstructor

public abstract CallSite invokeConstructor(MethodHandles.Lookup caller,
                         MethodType signature,
                         Class<?> owner)
                                    throws ReflectiveOperationException

Throws:

ReflectiveOperationException

getField

public abstract CallSite getField(MethodHandles.Lookup caller,
                String fieldName,
                Class<?> fieldType,
                Class<?> owner)
                           throws ReflectiveOperationException

Throws:

ReflectiveOperationException

putField

public abstract CallSite putField(MethodHandles.Lookup caller,
                String fieldName,
                Class<?> fieldType,
                Class<?> owner)
                           throws ReflectiveOperationException

Throws:

ReflectiveOperationException

getStatic

public abstract CallSite getStatic(MethodHandles.Lookup caller,
                 String fieldName,
                 Class<?> fieldType,
                 Class<?> owner)
                            throws ReflectiveOperationException

Throws:

ReflectiveOperationException

putStatic

public abstract CallSite putStatic(MethodHandles.Lookup caller,
                 String fieldName,
                 Class<?> fieldType,
                 Class<?> owner)
                            throws ReflectiveOperationException

Throws:

ReflectiveOperationException

register

public void register()

unregister

public void unregister()