Regex Parameter handler for Click

click_regex_option.py

import re
import sys
import typing as t

import click
from click._compat import _get_argv_encoding

  
class RegexOption(click.ParamType):
    """A type handler for click command parameters for Regex"""

    name: str = 'regular-expression'
    regex_flags: re.RegexFlag = 0

    def __init__(self, regex_flags: re.RegexFlag = 0):
        self.regex_flags = regex_flags

    def convert(
        self, value: t.Any, param: click.Parameter | None, ctx: click.Context | None
    ) -> re.Pattern:
        if isinstance(value, bytes):
            enc = _get_argv_encoding()
            try:
                value = value.decode(enc)
            except UnicodeError:
                fs_enc = sys.getfilesystemencoding()
                if fs_enc != enc:
                    try:
                        value = value.decode(fs_enc)
                    except UnicodeError:
                        value = value.decode("utf-8", "replace")
                else:
                    value = value.decode("utf-8", "replace")

        return re.compile(value, self.regex_flags)

    def __repr__(self) -> str:
        return "REGEX"


@click.command()
@click.option(
    '-p', '--pattern',
    type=RegexOption(), # Init with any desired flags (ie: re.IGNORECASE)
    prompt=True,
    help='The regex to compile',
)
def example(pattern):
    """Receives a compiled regex"""

    if not pattern.match('It Worked!'):
        click.echo('Pattern was not matched!')
        raise click.Abort()

    click.echo('The pattern was matched!')