Add Eclipse 4 RCP context function programmatically

Question

I am trying to bridge Guice 4 injector with Eclipse 4 RCP DI mechanism. What I would like to do is to create a ContextFunction, which would look up for values in Guice injector and bind them in IEclipseContext, something like this:

import org.eclipse.e4.core.contexts.ContextFunction;
import org.eclipse.e4.core.contexts.IEclipseContext;

import com.google.inject.Injector;

public class GuiceRCPBridgeFunction  extends ContextFunction 
{
    private Injector injector;

    public GuiceRCPBridgeFunction(Injector injector)
    {
        this.injector = injector;
    }

    @Override
    public Object compute(IEclipseContext context, String contextKey) 
    {
        // convert string key to type:
        Class<?> guiceKey = null;
        try {
            guiceKey = injector.getClass().getClassLoader().loadClass(contextKey);
        } 
        catch (ClassNotFoundException e) { throw new RuntimeException( e ); }

        // get instance from the injector:
        Object instance = injector.getInstance( guiceKey );

        // cache the instance in the eclipse context:
        context.set( contextKey, instance );

        return instance;
    }
}

I would like to know if there a way to attach this function after the Injecter is created, so that I could avoid putting the Injecter itself into the IEclipseContext?

Answer 1

Following seems to work, after putting the function under specific keys, as suggested by greg-449:

import org.eclipse.e4.core.contexts.ContextFunction;
import org.eclipse.e4.core.contexts.IEclipseContext;

import com.google.inject.Injector;
import com.google.inject.Key;

/**
 * Links guice and e4 RI  
 */
public class GuiceRCPBridgeFunction  extends ContextFunction 
{

    public static void link( Injector injector, IEclipseContext context )
    {
        GuiceRCPBridgeFunction function = new GuiceRCPBridgeFunction(injector);
        // add this function for every injector binding:
        for(Key <?> key : injector.getBindings().keySet())
        {
            String contextKey = key.getTypeLiteral().toString(); 
            Class classKey = function.loadClass( contextKey );
            context.set( classKey, function );
        }
    }

    private Injector injector;

    public GuiceRCPBridgeFunction(Injector injector)
    {
        this.injector = injector;

    }

    @Override
    public Object compute(IEclipseContext context, String contextKey) 
    {
        // convert string key to type:
        Class classKey = loadClass( contextKey );
        // get instance from the injector:
        Object instance = injector.getInstance( classKey );
        // cache the instance in the eclipse context:
        context.set(classKey, instance);

        return instance;
    }

    protected Class <?> loadClass( String className )
    {
        Class<?> guiceKey = null;
        try {
            guiceKey = injector.getClass().getClassLoader().loadClass(className);
        } 
        catch (ClassNotFoundException e) { throw new IllegalArgumentException( e ); }

        return guiceKey;
    }
}