# `pymcnp.ptrac` Subpackage

`pymcnp.ptrac` contains the PTRAC parser. PyMCNP implements an object-oriented recursive
descent parser, approximating PTRAC as the following context-free-grammar described in modified Backus-Naur form:

```
...
```

## Table of Contents

```{eval-rst}
.. toctree::
   :maxdepth: 1

   ptrac/header
   ptrac/history
```

## AST Classes

PyMCNP represents PTRAC non-terminals with AST classes and stores them in nested subpackages.
These AST class have methods for translating between PyMCNP and PTRAC:

* `from_mcnp`. Parses PTRAC source, checking for syntax and semantic errors.
* `to_mcnp`. Generates PTRAC source from PyMCNP objects, reformatting.

### `Header` Class

```{eval-rst}
.. autoclass:: pymcnp.ptrac.Header
   :members:
   :inherited-members:
```

[header subpackage](ptrac/header)

### `History` Class

```{eval-rst}
.. autoclass:: pymcnp.ptrac.History
   :members:
   :inherited-members:
```

[history subpackage](ptrac/history)