perf(const): const changed to a singelton

const needds to be accessed all throughout so it has been changed to a singleton to allow for more efficient usage

BREAKING CHANGE: Any previous loads to const will break, also constant->Constant and constants->Constants

src/const/public/const.h

@@ -10,7 +10,7 @@
 /**
  * @brief Structure to hold a constant's details.
  */
-struct constant {
+struct Constant {
   const std::string name;         ///< Name of the constant
   const double value;             ///< Value of the constant
   const double uncertainty;       ///< Uncertainty in the constant's value
@@ -25,13 +25,13 @@ struct constant {
    * @param unit The unit of the constant.
    * @param reference The reference for the constant's value.
    */
-  constant(const std::string& name, double value, double uncertainty, const std::string& unit, const std::string& reference)
+  Constant(const std::string& name, const double value, const double uncertainty, const std::string& unit, const std::string& reference)
     : name(name), value(value), uncertainty(uncertainty), unit(unit), reference(reference) {}
 
   /**
    * @brief overload the << operator for pretty printing
    */
-   friend std::ostream& operator<<(std::ostream& os, const constant& c) {
+   friend std::ostream& operator<<(std::ostream& os, const Constant& c) {
      os << "<" << c.name << ": ";
      os << c.value << "±" << c.uncertainty << " ";
      os << c.unit << " (" << c.reference << ")>\n";
@@ -42,18 +42,28 @@ struct constant {
 /**
  * @brief Class to manage a collection of constants.
  */
-class constants {
+class Constants {
 private:
   bool loaded_ = false; ///< Flag to indicate if constants are loaded
   const int col_widths_[6] = {25, 52, 20, 20, 17, 45}; // From the python script used to generate the constants file
-  std::map<std::string, constant> constants_; ///< Map to store constants by name
+  std::map<std::string, Constant> constants_; ///< Map to store constants by name
 
   /**
-   * @brief Load constants from a file.
-   * @param filename The name of the file to load constants from.
+   * @brief Default constructor. Private to avoid direct instantiation
+   */
+  Constants();
+
+  /**
+   * @brief Load constants from the embedded header file.
    * @return True if loading was successful, false otherwise.
    */
-  bool load(const std::string& filename);
+  bool load();
+
+  /**
+   * @brief Initialize constants.
+   * @return True if initialization was successful, false otherwise.
+   */
+  bool initialize();
 
   /**
    * @brief Trim leading and trailing whitespace from a string.
@@ -63,36 +73,28 @@ private:
   std::string trim(const std::string& str);
 
 public:
-  /**
-   * @brief Default constructor.
-   */
-  constants();
 
   /**
-   * @brief Constructor that initializes constants from a file.
-   * @param filename The name of the file to load constants from.
+   * @brief get instance of constants singelton
+   * @return instance of constants
    */
-  constants(const std::string& filename);
+  static Constants& getInstance() {
+    static Constants instance;
+    return instance;
+  }
 
   /**
    * @brief Check if constants are loaded.
    * @return True if constants are loaded, false otherwise.
    */
-  bool is_loaded() { return loaded_; }
-
-  /**
-   * @brief Initialize constants from a file.
-   * @param filename The name of the file to load constants from.
-   * @return True if initialization was successful, false otherwise.
-   */
-  bool initialize(const std::string& filename);
+  bool isLoaded() { return loaded_; }
 
   /**
    * @brief Get a constant by key.
    * @param key The name of the constant to retrieve.
    * @return The constant associated with the given key.
    */
-  constant get(const std::string& key) const;
+  Constant get(const std::string& key) const;
 
   /**
    * @brief Overloaded subscript operator to access constants by key.
@@ -100,7 +102,7 @@ public:
    * @return The constant associated with the given key.
    * @throws std::out_of_range if the key is not found.
    */
-  constant operator[](const std::string& key) const;
+  Constant operator[](const std::string& key) const;
 
   /**
    * @brief Check if a constant exists by key.