.. Copyright Celeritas contributors: see top-level COPYRIGHT file for details
.. SPDX-License-Identifier: CC-BY-4.0

.. _input:

*****
Input
*****

.. note:: This section is a sneak preview of Celeritas 1.0 input. It is *not*
   currently exposed to users.

.. only:: nobreathe

   .. warning:: The breathe_ extension was not used when building this version
      of the documentation. The input definitions will not be displayed.

   .. _breathe: https://github.com/michaeljones/breathe#readme

All front ends to Celeritas, and the library interface for external
integration, use a single interface to define properties about the simulation
to be run. This interface is a nested set of simple struct objects that are
used both to enable options and to set up low-level C++ data structures. Many
of the struct names in the ``inp`` namespace correspond to runtime Celeritas
classes and objects.

The highest-level problem definition input is:

.. doxygenstruct:: celeritas::inp::Problem
   :members:
   :no-link:

The following sections describe the members and their configuration options.
Note that most input classes (namespace ``inp``) match up with the runtime
classes that they help construct. Many of these definitions allow selection
between hard-coded C++ types via std::`variant`_ and optional types using
std::`optional`_.

.. _variant: https://en.cppreference.com/w/cpp/utility/variant
.. _optional: https://en.cppreference.com/w/cpp/utility/optional

Problems are loaded into the framework or application front end via :ref:`api_problem_setup`.

.. toctree::
   :maxdepth: 2
   :caption: Input definition

   input/model.rst
   input/physics.rst
   input/field.rst
   input/scoring.rst
   input/tracking.rst
   input/control.rst
   input/diagnostics.rst
   input/system.rst