80 lines
2.0 KiB
C++
80 lines
2.0 KiB
C++
/*
|
|
* Copyright (c) Meta Platforms, Inc. and affiliates.
|
|
*
|
|
* This source code is licensed under the MIT license found in the
|
|
* LICENSE file in the root directory of this source tree.
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include <list>
|
|
#include <memory>
|
|
|
|
namespace facebook::react::jsinspector_modern {
|
|
|
|
/**
|
|
* A list that holds weak pointers to objects of type `T`. Null pointers are not
|
|
* considered to be in the list.
|
|
*
|
|
* The list is not thread-safe! The caller is responsible for synchronization.
|
|
*/
|
|
template <typename T>
|
|
class WeakList {
|
|
public:
|
|
/**
|
|
* Call the given function for every element in the list, ensuring the element
|
|
* is not destroyed for the duration of the call. Elements are visited in the
|
|
* order they were inserted.
|
|
*
|
|
* As a side effect, any null pointers in the underlying list (corresponding
|
|
* to destroyed elements) will be removed during iteration.
|
|
*/
|
|
template <typename Fn>
|
|
void forEach(Fn&& fn) const {
|
|
for (auto it = ptrs_.begin(); it != ptrs_.end();) {
|
|
if (auto ptr = it->lock()) {
|
|
fn(*ptr);
|
|
++it;
|
|
} else {
|
|
it = ptrs_.erase(it);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Returns the number of (non-null) elements in the list. The count will only
|
|
* remain accurate as long as the list is not modified and elements are
|
|
* not destroyed.
|
|
*
|
|
* As a side effect, any null pointers in the underlying list (corresponding
|
|
* to destroyed elements) will be removed during this method.
|
|
*/
|
|
size_t size() const {
|
|
size_t count{0};
|
|
forEach([&count](const auto&) { ++count; });
|
|
return count;
|
|
}
|
|
|
|
/**
|
|
* Returns true if there are no elements in the list.
|
|
*
|
|
* As a side effect, any null pointers in the underlying list (corresponding
|
|
* to destroyed elements) will be removed during this method.
|
|
*/
|
|
bool empty() const {
|
|
return !size();
|
|
}
|
|
|
|
/**
|
|
* Inserts an element into the list.
|
|
*/
|
|
void insert(std::weak_ptr<T> ptr) {
|
|
ptrs_.push_back(ptr);
|
|
}
|
|
|
|
private:
|
|
mutable std::list<std::weak_ptr<T>> ptrs_;
|
|
};
|
|
|
|
} // namespace facebook::react::jsinspector_modern
|