Restored std::function callback support in FusionEngineFramer. (#308)

# Changes
- Restored `std::function` callback support in `FusionEngineFramer`, accidentally removed in 1.22.0
- Modified C-style callback API to take a `void*` context variable as an argument

src/point_one/fusion_engine/parsers/fusion_engine_framer.cc

@@ -377,10 +377,15 @@ int32_t FusionEngineFramer::OnByte(bool quiet) {
               << "), seq=" << header->sequence_number
               << ", size=" << current_message_size_
               << " B, crc=" << HexPrintableInteger(crc) << "]";
+      auto* payload = reinterpret_cast<uint8_t*>(header + 1);
+#if P1_HAVE_STD_FUNCTION
       if (callback_) {
-        auto* payload = reinterpret_cast<uint8_t*>(header + 1);
         callback_(*header, payload);
       }
+#endif // P1_HAVE_STD_FUNCTION
+      if (raw_callback_) {
+        raw_callback_(raw_callback_context_, *header, payload);
+      }
       state_ = State::SYNC0;
       return static_cast<int32_t>(current_message_size_);
     } else {

src/point_one/fusion_engine/parsers/fusion_engine_framer.h

@@ -5,8 +5,13 @@
 
 #pragma once
 
+#include "point_one/fusion_engine/common/portability.h"
+
 #include <cstddef> // For size_t
 #include <cstdint>
+#if P1_HAVE_STD_FUNCTION
+#  include <functional>
+#endif // P1_HAVE_STD_FUNCTION
 
 #include "point_one/fusion_engine/messages/defs.h"
 
@@ -40,9 +45,15 @@ namespace parsers {
  * framer.OnData(my_data, my_data_size);
  * ```
  */
-class P1_EXPORT FusionEngineFramer {
+class FusionEngineFramer {
  public:
-  using MessageCallback = void (*)(const messages::MessageHeader&, const void*);
+#if P1_HAVE_STD_FUNCTION
+  using MessageCallback =
+      std::function<void(const messages::MessageHeader&, const void*)>;
+#endif // P1_HAVE_STD_FUNCTION
+  using RawMessageCallback = void (*)(void* context,
+                                      const messages::MessageHeader& header,
+                                      const void* payload);
 
   /**
    * @brief Construct a framer instance with no buffer allocated.
@@ -51,14 +62,14 @@ class P1_EXPORT FusionEngineFramer {
    * You must call @ref SetBuffer() to assign a buffer, otherwise all incoming
    * data will be discarded.
    */
-  FusionEngineFramer() = default;
+  P1_EXPORT FusionEngineFramer() = default;
 
   /**
    * @brief Construct a framer instance with an internally allocated buffer.
    *
    * @param capacity_bytes The maximum framing buffer capacity (in bytes).
    */
-  explicit FusionEngineFramer(size_t capacity_bytes)
+  P1_EXPORT explicit FusionEngineFramer(size_t capacity_bytes)
       : FusionEngineFramer(nullptr, capacity_bytes) {}
 
   /**
@@ -71,9 +82,9 @@ class P1_EXPORT FusionEngineFramer {
    *        buffer internally.
    * @param capacity_bytes The maximum framing buffer capacity (in bytes).
    */
-  FusionEngineFramer(void* buffer, size_t capacity_bytes);
+  P1_EXPORT FusionEngineFramer(void* buffer, size_t capacity_bytes);
 
-  ~FusionEngineFramer();
+  P1_EXPORT ~FusionEngineFramer();
 
   // Don't allow copying or moving to avoid issues with managed buffer_.
   FusionEngineFramer(const FusionEngineFramer&) = delete; // Copy constructor
@@ -93,7 +104,7 @@ class P1_EXPORT FusionEngineFramer {
    *        buffer internally.
    * @param capacity_bytes The maximum framing buffer capacity (in bytes).
    */
-  void SetBuffer(void* buffer, size_t capacity_bytes);
+  P1_EXPORT void SetBuffer(void* buffer, size_t capacity_bytes);
 
   /**
    * @brief Enable/disable warnings for CRC and "message too large" failures.
@@ -105,20 +116,37 @@ class P1_EXPORT FusionEngineFramer {
    *
    * @param enabled If `true`, issue warnings on errors.
    */
-  void WarnOnError(bool enabled) { warn_on_error_ = enabled; }
+  P1_EXPORT void WarnOnError(bool enabled) { warn_on_error_ = enabled; }
 
+#if P1_HAVE_STD_FUNCTION
   /**
    * @brief Specify a function to be called when a message is framed.
    *
    * @param callback The function to be called with the message header and a
    *        pointer to the message payload.
    */
-  void SetMessageCallback(MessageCallback callback) { callback_ = callback; }
+  P1_EXPORT void SetMessageCallback(MessageCallback callback) {
+    callback_ = callback;
+  }
+#endif // P1_HAVE_STD_FUNCTION
+
+  /**
+   * @brief Specify a function to be called when a message is framed.
+   *
+   * @param callback The function to be called with the supplied context
+   *        variable, the message header, and a pointer to the message payload.
+   * @param context A context value that will be passed to the callback.
+   */
+  P1_EXPORT void SetMessageCallback(RawMessageCallback callback,
+                                    void* context) {
+    raw_callback_ = callback;
+    raw_callback_context_ = context;
+  }
 
   /**
    * @brief Reset the framer and discard all pending data.
    */
-  void Reset();
+  P1_EXPORT void Reset();
 
   /**
    * @brief Process incoming data.
@@ -129,7 +157,7 @@ class P1_EXPORT FusionEngineFramer {
    * @return The total size of all valid, complete messages, or 0 if no messages
    *         were completed.
    */
-  size_t OnData(const uint8_t* buffer, size_t length_bytes);
+  P1_EXPORT size_t OnData(const uint8_t* buffer, size_t length_bytes);
 
  private:
   enum class State {
@@ -139,7 +167,11 @@ class P1_EXPORT FusionEngineFramer {
     DATA = 3,
   };
 
-  MessageCallback callback_ = nullptr;
+#if P1_HAVE_STD_FUNCTION
+  MessageCallback callback_;
+#endif // P1_HAVE_STD_FUNCTION
+  RawMessageCallback raw_callback_ = nullptr;
+  void* raw_callback_context_ = nullptr;
 
   bool warn_on_error_ = true;
   bool is_buffer_managed_ = false;