com.oracle.truffle.api.dsl

Annotation Type CachedContext

@Retention(value=CLASS)
 @Target(value=PARAMETER)
public @interface CachedContext

Allows to access the current language execution context in specializations or exported messages. The cached context annotation requires to specify a concrete TruffleLanguage subclass in order to identify the language uniquely. The parameter type must be the language context type of the language or a TruffleLanguage.ContextReference that provides it. The latter parameter allows to lookup the context lazily, e.g. in a conditional branch. Using this annotation always allows to generate uncached versions of the node.

This annotation can be used in two different ways:

1. Direct context access:

 @GenerateUncached
 abstract static class ExampleNode extends Node {

     abstract Object execute(Object argument);

     @Specialization
     static int doInt(int value,
                     @CachedContext(MyLanguage.class) MyContext context) {
         // use context
         return value;
     }

 }
 

2. Conditional context access:

 @GenerateUncached
 abstract class ExampleNode extends Node {

     abstract Object execute(Object argument);

     @Specialization
     static int doInt(int value,
                     @CachedContext(MyLanguage.class) ContextReference ref) {
         if (value == 42) {
             // use context conditionally
             MyContext context = ref.get();

         }
         return value;
     }
 }
 

The generated code uses the Node.lookupContextReference(Class) method to implement this feature. This method may also be used manually.

Since:

19.0

See Also:

@Cached for more information on using this annotation., @CachedLanguage to access the language instance.

Required Element Summary

Required Elements

Modifier and Type	Required Element and Description
Class<? extends TruffleLanguage>	value Specifies the language the context should be looked up for.

Element Detail

value

public abstract Class<? extends TruffleLanguage> value

Specifies the language the context should be looked up for. Must be the exact language class annotated by TruffleLanguage.Registration.

Since:

19.0