fix-gcode.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import argparse
import re
import sys


DEFAULTS = {
    "input": sys.stdin,
    "output": sys.stdout,
    "speed": 800,
}

SUBSTITUTIONS = [
    ("G00 Z5.000000", "M03 S05\nG04 P0.3"),
    (" Z-0.125000", ""),
    ("G01 F100.0(Penetrate)", "G04 P0.3\nM03 S120"),
    ("F400", "F{speed}"),
]

def main(
    input=DEFAULTS["input"],
    output=DEFAULTS["output"],
    speed=DEFAULTS["speed"],
    substitutions=SUBSTITUTIONS
):
    context = {
        "speed": speed,
    }

    for line in input:
        for sub in substitutions:
            line = line.replace(sub[0], sub[1].format(**context))
        output.write(line)


description = """
Replaces common G-Code commands (eg: those generated by
the Path to GCode Inkscape extension) with equivalents 
that McGraw the Pen Plotter understands.

By default, incorrect G-Code is read from stdin,
and fixed G-Code is written to stdout.
"""

examples = """examples:
  cat /some/file.gcode | %(prog)s > /some/file-fixed.gcode
  cat /some/file.gcode | %(prog)s --speed 1200 | ./send-serial.py
  %(prog)s -i /some/file.gcode -o /some/file-fixed.gcode -s 1200
"""

if __name__ == "__main__":
    parser = argparse.ArgumentParser(
        description=description,
        epilog=examples,
        formatter_class=argparse.RawDescriptionHelpFormatter
    )

    parser.add_argument(
        "-i",
        "--input",
        metavar="FILE",
        nargs="?",
        type=argparse.FileType('r'),
        default=DEFAULTS["input"],
        help="read lines from the file at the given path, rather than from stdin"
    )
    parser.add_argument(
        "-o",
        "--output",
        metavar="FILE",
        nargs="?",
        type=argparse.FileType('w'),
        default=DEFAULTS["output"],
        help="output to a file at the given path, rather than stdout"
    )
    parser.add_argument(
        "-s",
        "--speed",
        default=DEFAULTS["speed"],
        help="drawing speed (default: %(default)s)"
    )

    args = parser.parse_args()

    main(input=args.input, output=args.output, speed=args.speed)