Few questions about invokeDynamic

[Christian Thalinger]

On Nov 9, 2010, at 4:25 PM, Rémi Forax wrote:
> Here is an example.
>   If indy has no parameter, it tests void -> indy return type
>   If indy has one parameter, it test parameter type -> return type
>   If indy name is "spread", a spread/collect is done.
> 
> Rémi
> 
> PS: With the new API, all identity methods but the one that take no 
> parameter
> can be removed and replace by Methodhandles.identity() in the BSM.

I just got back to this bug and now that InvokeDynamic is gone how can I rewrite that code to work again (without John's Indify magic)?

-- Christian

> 
> ---------------------------------------------------------------------------------------------------
> public class ConvertTest {
>   private static boolean identity(boolean v) {
>     return v;
>   }
>   private static byte identity(byte v) {
>     return v;
>   }
>   private static char identity(char v) {
>     return v;
>   }
>   private static short identity(short v) {
>     return v;
>   }
>   private static int identity(int v) {
>     return v;
>   }
>   private static long identity(long v) {
>     return v;
>   }
>   private static float identity(float v) {
>     return v;
>   }
>   private static double identity(double v) {
>     return v;
>   }
> 
>   private static void identity() { }
> 
>   private static void assertEquals(Object o, Object o2) {
>     if (!o.equals(o2))
>       throw new AssertionError("expected "+ o +" found "+o2);
>   }
> 
>   public static void main(String[] args) throws Throwable {
>     for(int i=0; i< 1000000; i++) {
>       boolean dummyZ; byte dummyB; short dummyS; char dummyC; int 
> dummyI; long dummyL; float dummyF; double dummyD;
> 
> 
>       //dummyZ = (boolean)InvokeDynamic.foo();  // void -> boolean
>       //dummyI = (int)InvokeDynamic.foo();  // void -> int
> 
>       //InvokeDynamic.foo(4);  // int -> void
>       InvokeDynamic.spread(4);  // spread: int -> void
> 
>       //dummyF = (float)InvokeDynamic.foo(4);  // int -> float
>       //dummyD = (double)InvokeDynamic.foo(4);  // int -> double
> 
>       //assertEquals(4.0f, (float)InvokeDynamic.foo(4));   // int -> float
>     }
>   }
> 
>   static {
>     Linkage.registerBootstrapMethod("bootstrap");
>   }
> 
>   private static CallSite bootstrap(Class<?> declaring, String name, 
> MethodType methodType) throws Throwable {
>     Lookup lookup = MethodHandles.lookup();
> 
>     MethodHandle mh;
>     if (methodType.parameterCount() == 0) {
>       mh = lookup.findStatic(ConvertTest.class, "identity", 
> MethodType.methodType(void.class));
>     } else {
>       Class<?> type = methodType.parameterType(0);
>       mh = lookup.findStatic(ConvertTest.class, "identity", 
> MethodType.methodType(type, type));
> 
>       if ("spread".equals(name)) {
>         mh = MethodHandles.spreadArguments(mh, 
> methodType.changeParameterType(0, Object[].class));
>         mh = MethodHandles.collectArguments(mh, methodType);
>       }
>     }
> 
>     mh = mh.asType(methodType);
> 
>     CallSite cs = new CallSite();
>     cs.setTarget(mh);
>     return cs;
>   }
> }