Summary:

Enhances the cheq library by embedding a comprehensive default parameter set directly into the binary. A new public function, get_default_parameters, provides convenient, thread-safe, and singleton-style access to these parameters. This change significantly improves the library's usability out-of-the-box, as users can now perform calculations without needing to manually create and load a parameter file for common elements.

Changes:

• Added Default TOML Parameter File:

  • Included resources/qeq.data.toml, a new file containing a comprehensive set of QEq parameters for elements 1 through 103.
  • The parameter file is extensively documented with information on units and data sources.

• Implemented Global Parameter Accessor:

  • Created a new public function get_default_parameters().
  • This function uses std::sync::OnceLock to lazily parse the embedded TOML file on its first call and caches the result for all subsequent calls.
  • This approach ensures efficient, thread-safe access to a single, static instance of the default Parameters.
  • Added a panic! with a descriptive error message in get_or_init to catch potential library build issues where the embedded file might be corrupted.

• Included Unit Tests for Default Parameters:

  • Added tests to verify that get_default_parameters successfully loads the parameters and contains expected elements (e.g., Carbon).
  • A test also confirms that subsequent calls to the function return a reference to the same cached instance, ensuring the singleton pattern is correctly implemented.