LocalPeer: implement

Creates generic data structure for peer information to be used by nodes and
local layers.

include/kvik/local_peer.hpp

@@ -0,0 +1,92 @@
+/**
+ * @file local_peer.hpp
+ * @author Dávid Benko (davidbenko@davidbenko.dev)
+ * @brief Local layer peer info
+ *
+ * @copyright Copyright (c) 2024
+ *
+ */
+
+#pragma once
+
+#include <algorithm>
+#include <array>
+#include <cstdint>
+
+#include "kvik/local_addr.hpp"
+
+namespace kvik
+{
+    /**
+     * @brief Retained local layer peer info
+     *
+     * Special form of `LocalPeer` without any dynamic memory allocation.
+     * Intended for storage in RTC memory of IoT microcontrollers (during deep
+     * sleep). Not used for anything else.
+     */
+    struct RetainedLocalPeer
+    {
+        std::array<uint8_t, 32> addr = {};
+        uint8_t addrLen = 0;
+        uint16_t channel = 0;
+    };
+
+    /**
+     * @brief Local layer peer info
+     */
+    struct LocalPeer
+    {
+        LocalAddr addr = {};  //!< Peer address
+        uint16_t channel = 0; //!< Wireless channel (only for wireless local layers)
+
+        bool operator==(const LocalPeer &other) const
+        {
+            return addr == other.addr;
+        }
+
+        bool operator!=(const LocalPeer &other) const
+        {
+            return !this->operator==(other);
+        }
+
+        inline bool empty() const
+        {
+            return addr.empty();
+        }
+
+        /**
+         * @brief Converts internal representation into printable string
+         * @return Printable string representation
+         */
+        inline std::string toString() const
+        {
+            return addr.toString();
+        }
+
+        /**
+         * @brief Converts `LocalPeer` to `RetainedLocalPeer`
+         *
+         * See `RetainedLocalPeer`'s docstring for usage details.
+         *
+         * @return Retained local peer info
+         */
+        inline const RetainedLocalPeer retain() const
+        {
+            RetainedLocalPeer rlp;
+            std::copy_n(addr.addr.begin(), rlp.addr.max_size(), rlp.addr.begin());
+            rlp.addrLen = addr.addr.size();
+            rlp.channel = channel;
+            return rlp;
+        }
+    };
+}
+
+// Define hasher function
+template <>
+struct std::hash<kvik::LocalPeer>
+{
+    std::size_t operator()(kvik::LocalPeer const &peer) const noexcept
+    {
+        return std::hash<kvik::LocalAddr>{}(peer.addr);
+    }
+};