Closes #14

core/decode_database.h

@@ -12,9 +12,11 @@
 #ifndef DECODE_DATABASE_H
 #define DECODE_DATABASE_H
 
-#include "value_descriptions.h"
+#include "definition_key.h"
 #include "multiplexing.h"
+#include "value_descriptions.h"
 #include <cstdint>
+#include <memory>
 #include <string>
 #include <unordered_map>
 #include <vector>
@@ -40,19 +42,19 @@ enum class ValueType {
  */
 struct DecodeSignal {
     Multiplexing multiplexing;
-    std::string name;                            /**< Signal name. */
-    std::uint32_t startBit = 0U;                 /**< DBC start bit. */
-    std::uint32_t length = 0U;                   /**< Signal length in bits. */
-    ByteOrder byteOrder = ByteOrder::Intel;      /**< Intel or Motorola. */
-    ValueType valueType = ValueType::Unsigned;   /**< Signed or unsigned. */
-    double factor = 1.0;                         /**< Scaling factor. */
-    double offset = 0.0;                         /**< Physical offset. */
-    double minimum = 0.0;                        /**< Minimum physical value. */
-    double maximum = 0.0;                        /**< Maximum physical value. */
-    std::string unit;                            /**< Physical unit. */
-    std::vector<std::string> receivers;          /**< Receivers. */
-    ValueDescriptions valueDescriptions;         /**< Raw integer state descriptions. */
-    std::string comment;                         /**< Comment. */
+    std::string name;                          /**< Signal name. */
+    std::uint32_t startBit = 0U;               /**< DBC start bit. */
+    std::uint32_t length = 0U;                 /**< Signal length in bits. */
+    ByteOrder byteOrder = ByteOrder::Intel;    /**< Intel or Motorola. */
+    ValueType valueType = ValueType::Unsigned; /**< Signed or unsigned. */
+    double factor = 1.0;                       /**< Scaling factor. */
+    double offset = 0.0;                       /**< Physical offset. */
+    double minimum = 0.0;                      /**< Minimum physical value. */
+    double maximum = 0.0;                      /**< Maximum physical value. */
+    std::string unit;                          /**< Physical unit. */
+    std::vector<std::string> receivers;        /**< Receivers. */
+    ValueDescriptions valueDescriptions;       /**< Raw integer state descriptions. */
+    std::string comment;                       /**< Comment. */
 
     DecodeSignal() = default;
 };
@@ -61,54 +63,52 @@ struct DecodeSignal {
  * @brief Runtime-ready frame definition.
  */
 struct DecodeFrame {
-    std::string name;                            /**< Frame name. */
-    std::uint32_t canId = 0U;                    /**< Normalized CAN ID. */
-    bool isExtended = false;                     /**< true for extended frame. */
-    std::uint8_t dlc = 0U;                       /**< Payload length. */
-    std::uint32_t pgn = 0U;                      /**< PGN if available. */
-    bool hasPgn = false;                         /**< true if PGN is valid. */
-    std::string transmitter;                     /**< Transmitter ECU. */
-    std::string comment;                         /**< Frame comment. */
-    std::vector<DecodeSignal> signals;           /**< Signal definitions. */
+    std::string name;                  /**< Frame name. */
+    std::uint32_t canId = 0U;          /**< Normalized CAN ID. */
+    bool isExtended = false;           /**< true for extended frame. */
+    std::uint8_t dlc = 0U;             /**< Payload length. */
+    std::uint32_t pgn = 0U;            /**< PGN if available. */
+    bool hasPgn = false;               /**< true if PGN is valid. */
+    std::string transmitter;           /**< Transmitter ECU. */
+    std::string comment;               /**< Frame comment. */
+    std::vector<DecodeSignal> signals; /**< Signal definitions. */
 
     DecodeFrame() = default;
-};
 
-/**
- * @brief Key for fast frame lookup.
- */
-struct FrameKey {
-    std::uint32_t canId = 0U;
-    bool isExtended = false;
-
-    FrameKey() = default;
-
-    FrameKey(std::uint32_t id, bool extended)
-        : canId(id), isExtended(extended) {
-    }
-
-    bool operator==(const FrameKey &other) const {
-        return (canId == other.canId) && (isExtended == other.isExtended);
+    FrameKey GetKey() const {
+        return FrameKey(canId, isExtended);
     }
 };
 
 /**
- * @brief Hasher for frame key.
+ * @brief Immutable runtime snapshot. Copies share storage; reload replaces a snapshot.
+ * Owning lookup handles and decoded results keep old definitions alive.
  */
-struct FrameKeyHasher {
-    std::size_t operator()(const FrameKey &key) const {
-        const std::size_t a = static_cast<std::size_t>(key.canId);
-        const std::size_t b = key.isExtended ? 1U : 0U;
-        return (a * 1315423911U) ^ b;
-    }
-};
+class DecodeDatabase {
+public:
+    DecodeDatabase() = default;
+    /**
+     * Freeze definitions and build the frame index.
+     * Do not retain mutable aliases into moved input vectors.
+     * @throws std::invalid_argument for duplicate frame keys or signal names.
+     */
+    explicit DecodeDatabase(std::vector<DecodeFrame> frames);
 
-/**
- * @brief Runtime decode database with fast lookup by CAN ID.
- */
-struct DecodeDatabase {
-    std::vector<DecodeFrame> frames;
-    std::unordered_map<FrameKey, std::size_t, FrameKeyHasher> frameIndexByKey;
+    /** Borrowed view, valid while this snapshot remains alive and unchanged. */
+    const std::vector<DecodeFrame> &GetFrames() const;
+    /** Owning handles retain the entire snapshot across reload or destruction. */
+    std::shared_ptr<const DecodeFrame> FindFrame(const FrameKey &key) const;
+    std::shared_ptr<const DecodeSignal> FindSignal(const SignalKey &key) const;
+
+private:
+    struct Storage {
+        std::vector<DecodeFrame> frames;
+        std::unordered_map<FrameKey, std::size_t, FrameKeyHasher> frameIndexByKey;
+
+        explicit Storage(std::vector<DecodeFrame> definitions);
+    };
+
+    std::shared_ptr<const Storage> storage;
 };
 
 #endif /* DECODE_DATABASE_H */