use espMqttClient, qos2 fixed

lib/espMqttClient/src/Outbox.h

@@ -0,0 +1,207 @@
+
+/*
+Copyright (c) 2022 Bert Melis. All rights reserved.
+
+This work is licensed under the terms of the MIT license.  
+For a copy, see <https://opensource.org/licenses/MIT> or
+the LICENSE file.
+*/
+
+#pragma once
+
+#include <new>  // new (std::nothrow)
+#include <utility>  // std::forward
+
+namespace espMqttClientInternals {
+
+/**
+ * @brief Singly linked queue with builtin non-invalidating forward iterator
+ * 
+ * Queue items can only be emplaced, at front and back of the queue.
+ * Remove items using an iterator or the builtin iterator.
+ */
+
+template <typename T>
+class Outbox {
+ public:
+  Outbox()
+  : _first(nullptr)
+  , _last(nullptr)
+  , _current(nullptr)
+  , _prev(nullptr) {}
+  ~Outbox() {
+    while (_first) {
+      Node* n = _first->next;
+      delete _first;
+      _first = n;
+    }
+  }
+
+  struct Node {
+   public:
+    template <typename... Args>
+    explicit Node(Args&&... args)
+    : data(std::forward<Args>(args) ...)
+    , next(nullptr) {
+      // empty
+    }
+
+    T data;
+    Node* next;
+  };
+
+  class Iterator {
+    friend class Outbox;
+   public:
+    void operator++() {
+      if (_node) {
+        _prev = _node;
+        _node = _node->next;
+      }
+    }
+
+    explicit operator bool() const {
+      if (_node) return true;
+      return false;
+    }
+
+    T* get() const {
+      if (_node) return &(_node->data);
+      return nullptr;
+    }
+
+   private:
+    Node* _node = nullptr;
+    Node* _prev = nullptr;
+  };
+
+  // add node to back, advance current to new if applicable
+  template <class... Args>
+  Iterator emplace(Args&&... args) {
+    Iterator it;
+    Node* node = new (std::nothrow) Node(std::forward<Args>(args) ...);
+    if (node != nullptr) {
+      if (!_first) {
+        // queue is empty
+        _first = _current = node;
+      } else {
+        // queue has at least one item
+        _last->next = node;
+        it._prev = _last;
+      }
+      _last = node;
+      it._node = node;
+      // point current to newly created if applicable
+      if (!_current) {
+        _current = _last;
+      }
+    }
+    return it;
+  }
+
+  // add item to front, current points to newly created front.
+  template <class... Args>
+  Iterator emplaceFront(Args&&... args) {
+    Iterator it;
+    Node* node = new (std::nothrow) Node(std::forward<Args>(args) ...);
+    if (node != nullptr) {
+      if (!_first) {
+        // queue is empty
+        _last = node;
+      } else {
+        // queue has at least one item
+        node->next = _first;
+      }
+      _current = _first = node;
+      _prev = nullptr;
+      it._node = node;
+    }
+    return it;
+  }
+
+  // remove node at iterator, iterator points to next
+  void remove(Iterator& it) {  // NOLINT(runtime/references)
+    if (!it) return;
+    Node* node = it._node;
+    Node* prev = it._prev;
+    ++it;
+    _remove(prev, node);
+  }
+
+  // remove current node, current points to next
+  void removeCurrent() {
+    _remove(_prev, _current);
+  }
+
+  // Get current item or return nullptr
+  T* getCurrent() const {
+    if (_current) return &(_current->data);
+    return nullptr;
+  }
+
+  void resetCurrent() {
+    _current = _first;
+  }
+
+  Iterator front() const {
+    Iterator it;
+    it._node = _first;
+    return it;
+  }
+
+  // Advance current item
+  void next() {
+    if (_current) {
+      _prev = _current;
+      _current = _current->next;
+    }
+  }
+
+  // Outbox is empty
+  bool empty() {
+    if (!_first) return true;
+    return false;
+  }
+
+ private:
+  Node* _first;
+  Node* _last;
+  Node* _current;
+  Node* _prev;  // element just before _current
+
+  void _remove(Node* prev, Node* node) {
+    if (!node) return;
+
+    // set current to next, node->next may be nullptr
+    if (_current == node) {
+      _current = node->next;
+    }
+
+    if (_prev == node) {
+      _prev = prev;
+    }
+
+    // only one element in outbox
+    if (_first == _last) {
+      _first = _last = nullptr;
+
+    // delete first el in longer outbox
+    } else if (_first == node) {
+      _first = node->next;
+
+    // delete last in longer outbox
+    } else if (_last == node) {
+      _last = prev;
+      _last->next = nullptr;
+
+    // delete somewhere in the middle
+    } else {
+      prev->next = node->next;
+    }
+
+    // finally, delete the node
+    delete node;
+  }
+};
+
+}  // end namespace espMqttClientInternals