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!
>>>>
>>> --
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