* The same call site may be used in several places at once. *
*/
MethodType MT_str2 = MethodType.methodType(String.class, String.class);
MethodHandle MH_cat = lookup().findVirtual(String.class,
"concat", methodType(String.class, String.class));
MethodHandle MH_dear = MethodHandles.insertArguments(MH_cat, 1, ", dear?");
MethodHandle worker2 = MethodHandles.filterReturnValue(MH_name, MH_dear);
assertEquals("Fred, dear?", (String) worker2.invokeExact());
name.setTarget(MethodHandles.constant(String.class, "Wilma"));
assertEquals("WILMA", (String) worker1.invokeExact());
assertEquals("Wilma, dear?", (String) worker2.invokeExact());
{}
}}
}
@Test public void testSwitchPoint() throws Throwable {
{{
{} /// JAVADOC
MethodHandle MH_strcat = MethodHandles.lookup()
.findVirtual(String.class, "concat", MethodType.methodType(String.class, String.class));
SwitchPoint spt = new SwitchPoint();
assert(!spt.hasBeenInvalidated());
// the following steps may be repeated to re-use the same switch point:
MethodHandle worker1 = MH_strcat;
MethodHandle worker2 = MethodHandles.permuteArguments(MH_strcat, MH_strcat.type(), 1, 0);
MethodHandle worker = spt.guardWithTest(worker1, worker2);
assertEquals("method", (String) worker.invokeExact("met", "hod"));
SwitchPoint.invalidateAll(new SwitchPoint[]{ spt });
assert(spt.hasBeenInvalidated());
assertEquals("hodmet", (String) worker.invokeExact("met", "hod"));
{}
}}
}
@Test public void testFoldArguments2() throws Throwable {
{{
{} /// JAVADOC
// argument-based dispatch for methods of the form boolean x.___(y: String)
Lookup lookup = publicLookup();
// first, a tracing hack:
MethodHandle println = lookup.findVirtual(java.io.PrintStream.class, "println", methodType(void.class, String.class));
MethodHandle arrayToString = lookup.findStatic(Arrays.class, "toString", methodType(String.class, Object[].class));
MethodHandle concat = lookup.findVirtual(String.class, "concat", methodType(String.class, String.class));
MethodHandle arrayToString_DIS = filterReturnValue(arrayToString, concat.bindTo("DIS:"));
MethodHandle arrayToString_INV = filterReturnValue(arrayToString, concat.bindTo("INV:"));
MethodHandle printArgs_DIS = filterReturnValue(arrayToString_DIS, println.bindTo(System.out)).asVarargsCollector(Object[].class);
MethodHandle printArgs_INV = filterReturnValue(arrayToString_INV, println.bindTo(System.out)).asVarargsCollector(Object[].class);
// metaobject protocol:
MethodType mtype = methodType(boolean.class, String.class);
MethodHandle findVirtual = lookup.findVirtual(Lookup.class,
"findVirtual", methodType(MethodHandle.class, Class.class, String.class, MethodType.class));
MethodHandle getClass = lookup.findVirtual(Object.class,
"getClass", methodType(Class.class));
MethodHandle dispatch = findVirtual;
dispatch = filterArguments(dispatch, 1, getClass);
dispatch = insertArguments(dispatch, 3, mtype);
dispatch = dispatch.bindTo(lookup);
assertEquals(methodType(MethodHandle.class, Object.class, String.class), dispatch.type());
MethodHandle invoker = invoker(mtype.insertParameterTypes(0, Object.class));
// wrap tracing around the dispatch and invoke steps:
dispatch = foldArguments(dispatch, printArgs_DIS.asType(dispatch.type().changeReturnType(void.class)));
invoker = foldArguments(invoker, printArgs_INV.asType(invoker.type().changeReturnType(void.class)));
invoker = dropArguments(invoker, 2, String.class); // ignore selector
// compose the dispatcher and the invoker:
MethodHandle invokeDispatched = foldArguments(invoker, dispatch);
Object x = "football", y = new java.util.Scanner("bar");
assert( (boolean) invokeDispatched.invokeExact(x, "startsWith", "foo"));
assert(!(boolean) invokeDispatched.invokeExact(x, "startsWith", "#"));
assert( (boolean) invokeDispatched.invokeExact(x, "endsWith", "all"));
assert(!(boolean) invokeDispatched.invokeExact(x, "endsWith", "foo"));
assert( (boolean) invokeDispatched.invokeExact(y, "hasNext", "[abc]+[rst]"));
assert(!(boolean) invokeDispatched.invokeExact(y, "hasNext", "[123]+[789]"));
}}
}
/* ---- TEMPLATE ----
@Test public void testFoo() throws Throwable {
{{
{} /// JAVADOC
{}
}}
}
*/
}