Compile HTCondor if-then cases to a single if-then-else tree

condor_switch.py

#!/usr/bin/env python3
from typing import Dict


def switch(cases: Dict[str, str], default='UNDEFINED', separator='\n'):
    # ["IfThenElse(ac, am", "IfThenElse(bc, bm", "IfThenElse(cc, cm", ...]
    switch_expression = separator.join(
        f"IfThenElse({condition}, {on_match},"
        for condition, on_match in cases.items()
    )
    return (
        f"{switch_expression}{separator}{default}{')' * len(cases)}"
        if switch_expression else default
    )


if __name__ == "__main__":
    import argparse
    import sys

    if sys.version_info[:2] < (3, 6):
        print(f"Python 3.6 or newer required", file=sys.stderr)
        sys.exit(1)

    parser = argparse.ArgumentParser(
        formatter_class=argparse.RawDescriptionHelpFormatter,
        description="Compile HTCondor if-then cases to a single if-then-else tree",
        epilog=(
            "Example:\n"
            """  %(prog)s 'Owner == "Bruce"' '"Batman"'"""
            """ 'Owner == "Clark"' '"Superman"' --default '"Joker"'"""
        ),
    )
    parser.add_argument(
        "cases",
        nargs="*",
        default=[],
        help="pairs of condition and result",
    )
    parser.add_argument(
        "--default",
        default='UNDEFINED',
        help="fallback if no case matches",
    )
    parser.add_argument(
        "--multiline",
        action="store_true",
        help="whether to spread each case onto a new line",
    )
    settings = parser.parse_args()
    if len(settings.cases) % 2:
        print(f"cases must be pairs (multiple of 2)", file=sys.stderr)
        sys.exit(1)
    print(
        switch(
            cases=dict(zip(settings.cases[::2], settings.cases[1::2])),
            default=settings.default,
            separator='\n' if settings.multiline else ' ',
        )
    )