private static MethodHandle buildVarargsArray(
MethodHandle newArray, MethodHandle finisher, int nargs) {
// Build up the result mh as a sequence of fills like this:
// finisher(fill(fill(newArrayWA(23,x1..x10),10,x11..x20),20,x21..x23))
// The various fill(_,10*I,___*[J]) are reusable.
int leftLen = Math.min(nargs, LEFT_ARGS); // absorb some arguments immediately
int rightLen = nargs - leftLen;
MethodHandle leftCollector = newArray.bindTo(nargs);
leftCollector = leftCollector.asCollector(Object[].class, leftLen);
MethodHandle mh = finisher;
if (rightLen > 0) {
MethodHandle rightFiller = fillToRight(LEFT_ARGS + rightLen);
if (mh == ARRAY_IDENTITY) mh = rightFiller;
else mh = MethodHandles.collectArguments(mh, 0, rightFiller);
}
if (mh == ARRAY_IDENTITY) mh = leftCollector;
else mh = MethodHandles.collectArguments(mh, 0, leftCollector);
return mh;
}
