jxconfig 0.1.0

JX — JSON eXtended: a minimal JSON-compatible config language with comments, trailing commas, and expressions

JX — JSON eXtended

A minimal, deterministic JSON-compatible configuration language with three deliberate extensions. JX is a lightweight preprocessor for configuration files — not a general-purpose programming language.

Features

Extension	Description
Inline comments	// single-line comments (block comments intentionally excluded)
Trailing commas	Allowed in objects and arrays; stripped before JSON parsing
Numeric expressions	Object keys define variables; reference them with ${name}; supports + - * / ( )

Beyond the basics

• #include directives — import other JX files with optional path extraction and aliasing: #include "other.jx"[a.b.c] as alias
• Math constants — pi, e, tau built in
• Static globals — true, false, null, nan, inf, -inf
• All math module functions — plus max, min, round, abs
• Nested scopes — inner objects shadow outer keys; evaluation is single-pass and order-dependent

Installation

pip install jxconfig

Or from source:

pip install git+https://github.com/KrisTHL181/jxconfig.git

Quick Start

from jxconfig import load_jx

# Load from a string
config = load_jx('''
{
    // server configuration
    base_port: 8000,
    workers: 4,
    total_ports: base_port + workers,  // 8004
    pi_area: 3 * pi * 2 ** 2,          // math constants
}
''')

print(config["total_ports"])  # 8004

Including other files

db.jx:

{
    host: "localhost",
    port: 5432,
}

app.jx:

{
    #include "db.jx"[host, port] as db

    name: "myapp",
    connection: "${db.host}:${db.port}",
}

From a file

from jxconfig import load_jx

with open("config.jx") as f:
    config = load_jx(f.read(), current_dir="configs/")

# All top-level keys are accessible by name
print(config["name"])

Language Spec

JX files are valid JSON with three relaxations:

1. Comments — // to end of line
2. Trailing commas — {"a": 1,} and [1, 2,] are legal
3. Unquoted expression values — after :, an expression may be written without quotes; variables are interpolated with ${name}

Expressions support the standard arithmetic operators (+, -, *, /, parentheses) plus all Python math module functions and constants.

API

load_jx(text: str, current_dir: str = ".") -> dict

Parse and evaluate a JX string. current_dir sets the base directory for resolving relative #include paths.

evaluate(value, scope: dict) -> Any

Recursively evaluate expressions in a parsed JSON structure.

eval_expression(expr: str, scope: dict) -> Any

Evaluate a single expression string against a variable scope.

process_directives(text: str, current_dir: str, seen_files: set) -> tuple[str, dict]

Pre-process #include directives before JSON parsing.

License

MIT