The Local class defines an operator == that should do exactly what you need.
On Thu, Jun 21, 2018 at 5:43 AM Gonzalo Diethelm <gonzalo.dieth...@gmail.com> wrote: > 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. > -- -- 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.