private static MethodHandle buildFiller(int nargs) {
if (nargs <= LEFT_ARGS) return ARRAY_IDENTITY; // no args to fill; return the array unchanged
// we need room for both mh and a in mh.invoke(a, arg*[nargs])
final int CHUNK = LEFT_ARGS;
int rightLen = nargs % CHUNK;
int midLen = nargs - rightLen;
if (rightLen == 0) {
midLen = nargs - (rightLen = CHUNK);
if (FILL_ARRAY_TO_RIGHT[midLen] == null) {
// build some precursors from left to right
for (int j = LEFT_ARGS % CHUNK; j < midLen; j += CHUNK) if (j > LEFT_ARGS) fillToRight(j);
}
}
if (midLen < LEFT_ARGS) rightLen = nargs - (midLen = LEFT_ARGS);
assert (rightLen > 0);
MethodHandle midFill = fillToRight(midLen); // recursive fill
MethodHandle rightFill = FILL_ARRAYS[rightLen].bindTo(midLen); // [midLen..nargs-1]
assert (midFill.type().parameterCount() == 1 + midLen - LEFT_ARGS);
assert (rightFill.type().parameterCount() == 1 + rightLen);
// Combine the two fills:
// right(mid(a, x10..x19), x20..x23)
// The final product will look like this:
// right(mid(newArrayLeft(24, x0..x9), x10..x19), x20..x23)
if (midLen == LEFT_ARGS) return rightFill;
else return MethodHandles.collectArguments(rightFill, 0, midFill);
}
public static MethodHandle convertPrimitive(Wrapper wsrc, Wrapper wdst) {
EnumMap<Wrapper, MethodHandle> cache = CONVERT_PRIMITIVE_FUNCTIONS[wsrc.ordinal()];
MethodHandle mh = cache.get(wdst);
if (mh != null) {
return mh;
}
// slow path
Class<?> src = wsrc.primitiveType();
Class<?> dst = wdst.primitiveType();
MethodType type =
src == void.class ? MethodType.methodType(dst) : MethodType.methodType(dst, src);
if (wsrc == wdst) {
mh = identity(src);
} else if (wsrc == Wrapper.VOID) {
mh = zeroConstantFunction(wdst);
} else if (wdst == Wrapper.VOID) {
mh = MethodHandles.dropArguments(EMPTY, 0, src); // Defer back to MethodHandles.
} else if (wsrc == Wrapper.OBJECT) {
mh = unboxCast(dst);
} else if (wdst == Wrapper.OBJECT) {
mh = box(src);
} else {
assert (src.isPrimitive() && dst.isPrimitive());
try {
mh =
IMPL_LOOKUP.findStatic(
THIS_CLASS, src.getSimpleName() + "To" + capitalize(dst.getSimpleName()), type);
} catch (ReflectiveOperationException ex) {
mh = null;
}
}
if (mh != null) {
assert (mh.type() == type) : mh;
cache.put(wdst, mh);
return mh;
}
throw new IllegalArgumentException(
"cannot find primitive conversion function for "
+ src.getSimpleName()
+ " -> "
+ dst.getSimpleName());
}
private static boolean assertCorrectArity(MethodHandle mh, int arity) {
assert (mh.type().parameterCount() == arity) : "arity != " + arity + ": " + mh;
return true;
}