pw_containers

Generic collections of objects for embedded devices

Stable C++17 Code Size Impact: 200 to 3300 bytes

• Familiar: Pigweed containers resemble standard library containers.

• Comprehensive: You can pick containers for speed, size, or in-between.

• Embedded-friendly: No dynamic allocation needed!

class Publisher {
 public:
  using Subscriber = pw::Function<void(const Message&)>;
  static constexpr size_t kMaxSubscribers = 10;

  pw::Status Subscribe(Subscriber&& subscriber) {
    // Check if the vector's fixed capacity has been exhausted.
    if (subscribers_.full()) {
      return pw::Status::ResourceExhausted();
    }

    // Add the subscriber to the vector.
    subscribers_.emplace_back(std::move(subscriber));
    return pw::OkStatus();
  }

  void Publish(const Message& message) {
    // Iterate over the vector.
    for (auto& subscriber : subscribers_) {
      subscriber(message);
    }
  }

 private:
  pw::Vector<Subscriber, kMaxSubscribers> subscribers_;
};

Much like the standard containers library, the pw_containers module provides embedded-friendly container class templates and algorithms. These allow developers to implement data structures for embedded devices that are more resource-constrained than conventional applications. These containers include:

Lists

Intrusive singly and doubly linked lists.

Maps

Key-value stores with constant or logarithmic performance.

Queues

Uni- and bidirectional FIFOs.

Sets

Unordered collections with fast lookup, insertion, and deletion.

Utilities

Algorithms and iterators for Pigweed containers.

Vector

Variable length array with fixed storage.

Zephyr

To enable pw_containers for Zephyr add CONFIG_PIGWEED_CONTAINERS=y to the project’s configuration.