Sure, slot does have a value, I just didn't include it in the code. Something like:
Local<Value> slot = String::NewFromUtf8(isolate, "MyBeautifulSlot", NewStringType::kNormal).ToLocalChecked(); Cheers! On Thursday, June 21, 2018 at 2:27:00 PM UTC+2, Zac Hansen wrote: > > You're dereferencing a "super pointer" to get to a "pointer", hence * not > &. You can't "go back" because the local/global<T> represents an > "reference count" to the object which must be known to the JS runtime. > > As for p0 and p1, have you tried setting slot to a fixed string value > before using it as a key for storing/lookup? I don't know what the > expected behavior of using an empty value as a key into an object is. > > These are all just guesses - if someone else answers differently, I'm > probably wrong. > > > On Thursday, June 21, 2018 at 5:07:50 AM UTC-7, Gonzalo Diethelm wrote: >> >> Note to self: this might be related to Local<Object> vs Global<Object> >> (or Persistent<Object>? so many names...) >> >> Need to look into that. >> >> On Thursday, June 21, 2018 at 7:58:37 AM UTC+2, Gonzalo Diethelm wrote: >>> >>> I run the following JS code in the Chrome console: >>> >>> // Version 67.0.3396.87 (Official Build) (64-bit) >>> >>> var x = [1, 2, {"foo": 11}]; >>> x[2].bar = x; >>> >>> Now from C++ code, I get ahold of x as a Local<Object>, and wish to >>> traverse the whole structure; for the sake of the example, let's say I am >>> converting it into serialized data (I know I can use JSON.stringify() to do >>> this, serializing is just an example to clarify ideas). My question is, >>> how can I keep track of the nodes in the structure that I have already >>> seen, and their associated serialized value, so that I can avoid an >>> infinite traversal? >>> >>> It seems to me doing this would require a way to get a unique identity >>> for each node, so that the C++ code can do something similar to this: >>> >>> typedef map<NodeId, NodeData> NodeMap; >>> NodeMap seen; >>> ... >>> Local<Object> node = current.GetNextChild(); >>> NodeId id = node.GetUniqueId(); >>> NodeMap::iterator k = seen.find(id); >>> NodeData data; >>> if (k != seen.end()) { >>> // node already seen, reuse its serialization >>> data = k->first; >>> } else { >>> // first time we see node, serialize and remember >>> data = node.Serialize(); // recurses >>> seen[id] = data; >>> } >>> >>> The specific question is: what type could be NodeId, and how do I get >>> the equivalent of GetUniqueId()? >>> >>> I am very tempted to ask for a way to get a raw void* to each node, but >>> I guess any way of doing this is fine, as long as I can get a unique id >>> that is stable while I'm traversing the data. For these reasons, >>> GetIdentityHash() does not seem to fit the bill: "*The return value >>> will never be 0. Also, it is not guaranteed to be unique.*" >>> >>> Incidentally, If I try to use JSON.stringify for my data, I get this: >>> >>> JSON.stringify(x) >>> VM170:1 Uncaught TypeError: Converting circular structure to JSON >>> at JSON.stringify (<anonymous>) >>> at <anonymous>:1:6 >>> >>> This is taken care of here in the V8 code: >>> >>> JsonStringifier::Result JsonStringifier::StackPush(Handle<Object> object >>> ) { >>> ... >>> // member stack_ is: Handle<JSArray> stack_; >>> int length = Smi::ToInt(stack_->length()); >>> FixedArray* elements = FixedArray::cast(stack_->elements()); >>> for (int i = 0; i < length; i++) { >>> FixedArray* elements = FixedArray::cast(stack_->elements()); >>> if (elements->get(i) == *object) { >>> // boom >>> } >>> } >>> } >>> >>> So, operator*() in a Handle<Object> gives me a unique id? Which is the >>> type for this? Can I store that in a C++ map? Is it stable (enough)? >>> >>> Thanks! >>> >> -- -- v8-users mailing list v8-users@googlegroups.com http://groups.google.com/group/v8-users --- You received this message because you are subscribed to the Google Groups "v8-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to v8-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.