public static int getNativeArgCount(DynamicMethod method, DynamicMethod.NativeCall nativeCall) {
// if non-Java, must:
// * exactly match arities or both are [] boxed
// * 3 or fewer arguments
return getArgCount(nativeCall.getNativeSignature(), nativeCall.isStatic());
}
static MethodHandle buildNativeHandle(InvokeSite site, DynamicMethod method, boolean blockGiven) {
MethodHandle mh = null;
SmartBinder binder = null;
if (method.getNativeCall() != null) {
int nativeArgCount = getNativeArgCount(method, method.getNativeCall());
DynamicMethod.NativeCall nc = method.getNativeCall();
if (nc.isJava()) {
// not supported yet, use DynamicMethod.call
} else {
if (nativeArgCount >= 0) { // native methods only support arity 3
if (nativeArgCount == site.arity) {
// nothing to do
binder = SmartBinder.from(lookup(), site.signature);
} else {
// arity mismatch...leave null and use DynamicMethod.call below
}
} else {
// varargs
if (site.arity == -1) {
// ok, already passing []
binder = SmartBinder.from(lookup(), site.signature);
} else if (site.arity == 0) {
// no args, insert dummy
binder =
SmartBinder.from(lookup(), site.signature)
.insert(2, "args", IRubyObject.NULL_ARRAY);
} else {
// 1 or more args, collect into []
binder = SmartBinder.from(lookup(), site.signature).collect("args", "arg.*");
}
}
if (binder != null) {
// clean up non-arguments, ordering, types
if (!nc.hasContext()) {
binder = binder.drop("context");
}
if (nc.hasBlock() && !blockGiven) {
binder = binder.append("block", Block.NULL_BLOCK);
} else if (!nc.hasBlock() && blockGiven) {
binder = binder.drop("block");
}
if (nc.isStatic()) {
mh =
binder
.permute("context", "self", "arg.*", "block") // filter caller
.cast(nc.getNativeReturn(), nc.getNativeSignature())
.invokeStaticQuiet(LOOKUP, nc.getNativeTarget(), nc.getNativeName())
.handle();
} else {
mh =
binder
.permute("self", "context", "arg.*", "block") // filter caller, move self
.castArg("self", nc.getNativeTarget())
.castVirtual(
nc.getNativeReturn(), nc.getNativeTarget(), nc.getNativeSignature())
.invokeVirtualQuiet(LOOKUP, nc.getNativeName())
.handle();
}
}
}
}
return mh;
}