Jakob, you rule. That in fact fixed all my problems. Thanks to you and Zac
for all the guidance!
On Thursday, June 21, 2018 at 11:12:24 PM UTC+2, Jakob Kummerow wrote:
>
> 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....@gmail.com
> <javascript:>> 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-u...@googlegroups.com <javascript:>
>> 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+u...@googlegroups.com <javascript:>.
>> 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.
