Scuff

A slick config file format for humans.

Introduction

Scuff is a language suite with a slick, efficient, flexible syntax, unique features and useful tools.

Its purpose is to represent structured data effectively. Scuff's greatest strengths are its syntactic simplicity and reliable flexibility. It comes with a Python API and a simple command line tool for moving data between JSON syntax, Python's and its own.

One excellent use for Scuff is to encode and parse configuration files.

Scuff implements its own custom lexer, recursive-descent parser and transpiler to read and process data. Though written in Python, the parser is immune from Python's recursion limit.

Installation

To install Scuff and its tools for Python from the Python Package Index, run the following in the command line:

$ python -m pip install scuff

Grammar

Assigning Variables

Variables are assigned with a key and a value. Key names must be valid identifiers, meaning they must contain no spaces or symbols except underscore (_). Values can be assigned to variables with or without an equals sign (=):

my_favorite_number = 42
my_favorite_color "Magenta"
is_but_a_flesh_wound yes

When left without a value, variables will evaluate to null or None:

set_to_null =
also_null
but_this_has_a_value 15

Data Types

• Numbers

  Numbers can be integers or floats:

  1 1.2 -1_000 0.123 .123_4
  

• Booleans

  The boolean values True and False are given using these variants:

  True true yes
  False false no
  

  They are case-insensitive, so yes and yES both evaluate to True.

• Strings

  Single-line strings can be enclosed by single quotes ('), double quotes (") or backticks (`), and multiline strings are enclosed by three of any one:

  foo "abc"
  bar 'def'
  baz '''Hi,
          did you know
              you're cute?
                  '''

• Lists

  Lists are enclosed by square brackets ([]). Elements inside lists are separated by spaces, commas or line breaks:

  groceries [
      "bread",
      "milk" "eggs"
      "spam"
  ]

• Mappings

  Mappings are groups of key-value pairs enclosed by curly braces ({}). Values may be any expression, even other mappings:

  me {
      name "Samantha"
      age 24
      job "Developer"
      favorite_things {
          editor "Vim"
          languages ["Python", "Rust"]
      }
  }

  Mappings may also take the form of dotted attribute lookups:

  outer.middle.inner yes

  evauates in Python to

  {'outer': {'middle': {'inner': True}}}

• Comments

  Single-line comments are made using the # symbol:

  option = "The parser reads this."
  # But this is a comment.
      #And so is this.
  option2 = "# But not this; It's inside a string."
  # The parser ignores everything between ``#`` and the end of the line.
   #   ignore = "Comment out any lines of code you want to skip."

Python Usage

Once you install Scuff, you can then import scuff as a Python module and use its tools:

>>> import scuff
>>> scuff.to_json('menu {border.color "#aa22bb", font.color "#cdcdcd"}')
'{"menu": {"border": {"color": "#aa22bb"}, "font": {"color": "#cdcdcd"}}}'

>>> type(scuff.to_py('Documents/file.conf'))
<class 'dict'>

>>> scuff.to_py('a.b ["c", "d"]')
{'a': {'b': ['c', 'd']}}

>>> scuff.parse('hovercraft ["eel" "eel" "eel" "eel"]')
<ast.Module object at 0x74b59c109710>
>>> print(scuff.dump(_))
Module(
  body=[
    Assign(
      targets=[
        Name(id='hovercraft')],
      value=List(
        elts=[
          Constant(value='eel'),
          Constant(value='eel'),
          Constant(value='eel'),
          Constant(value='eel')]))])

Command Line Usage

Scuff also comes with a command line tool for converting between formats:

usage: scuff [-h] [-j] [-p] [-a] [--debug] [-v] source [source ...]

positional arguments:
  source           The file path(s) or literal Scuff to process.

options:
  -h, --help       show this help message and exit
  -j, --to-json    Convert `source` to JSON.
  -p, --to-python  Convert `source` to Python.
  -a, --show-ast   Parse `source` and show its equivalent AST.
  --debug          Use debug mode. (Not implemented)
  -v, --version    show program's version number and exit

Multiple files and strings may be converted in multiple ways at once:

$ python -m scuff --to-json ~/.config/mybar/mybar.conf 'foo {a{b [1,{c 3}]}}'
{"field_order": ["hostname", "uptime", "cpu_usage", "cpu_temp", "mem_usage", "disk_usage", "battery", "net_stats", "datetime"], "field_icons": {"uptime": ["Up ", "\uf2f2 "], "cpu_usage": ["CPU ", "\uf3fd "], "cpu_temp": ["", "\uf06d "], "mem_usage": ["MEM ", "\uf2db "], "disk_usage": ["/: ", "\uf233 "], "battery": ["BAT ", "\uf242 "], "net_stats": ["", "\uf1eb"]}}

{"foo": {"a": {"b": [1, {"c": 3}]}}}