msdparser

A comprehensive, pure-Python, speed-optimized MSD parser. MSD is the underlying file format for the SM and SSC simfile formats used by StepMania, as well as a few older formats like DWI.

Full documentation can be found on Read the Docs.

Features

• MSD lexer and parser
• Optional escape sequences (on by default)
• Optional strict parsing (off by default)
• Bidirectionally-lossless parsing & serialization (in most cases)

Installation

msdparser is available on PyPI:

pip install msdparser

Quickstart

parse_msd takes a named file or string argument and yields MSDParameter instances:

>>> msd_data = """
... #VERSION:0.83;
... #TITLE:Springtime;
... #SUBTITLE:;
... #ARTIST:Kommisar;
... """
>>> from msdparser import parse_msd
>>> for param in parse_msd(string=msd_data):
...         print(
...             "key=" + repr(param.key),
...             "value=" + repr(param.value),
...         )
...
key='VERSION' value='0.83'
key='TITLE' value='Springtime'
key='SUBTITLE' value=''
key='ARTIST' value='Kommisar'

MSDParameter instances stringify back to MSD. They can be created from a sequence of strings, typically the key and value:

>>> from msdparser import MSDParameter
>>> pairs = [('TITLE', 'Springtime'), ('ARTIST', 'Kommisar')]
>>> for key, value in pairs:
...     print(str(MSDParameter([key, value])))
...
#TITLE:Springtime;
#ARTIST:Kommisar;

Parameters can be stringified exactly how they were parsed by calling serialize or stringify with exact=True:

>>> import codecs
>>> import filecmp
>>> from msdparser import MSDParameter, parse_msd
>>> with codecs.open("tests/testdata/backup.ssc", encoding="utf-8") as infile:
...     params = list(parse_msd(file=infile))
...
>>> with codecs.open("output.ssc", "w", encoding="utf-8") as outfile:
...     for param in params:
...         param.serialize(outfile, exact=True)
...
>>> filecmp.compare("tests/testdata/backup.ssc", "output.ssc")
True

Developing

msdparser uses uv for package management. Install it using pipx install uv or pip install uv, or see the installation docs for more options.

Create the virtual environment for msdparser:

uv sync

Activate the virtual environment:

# Windows
.venv\Scripts\activate
# Linux / Mac
source .venv/bin/activate

Run the unit tests:

uv run -m unittest
# Or, if you've activated your virtual environment:
python -m unittest

Build the documentation:

docs/make html