simplematch.py

#!/usr/bin/env python3
"""
simplematch
"""
import re
from collections import namedtuple

# taken from the standard re module - minus "*{}", because that's our own syntax
SPECIAL_CHARS = {i: "\\" + chr(i) for i in b"()[]?+-|^$\\.&~# \t\n\r\v\f"}

# a regex that ensures all groups to be non-capturing. Otherwise they would appear in
# the matches
TYPE_CLEANUP_REGEX = re.compile(r"(?<!\\)\((?!\?)")

# `types` is the dict of known types that is filled with register_type
Type = namedtuple("Type", "regex converter")
types = {}


def register_type(name, regex, converter=str):
    """register a type to be available for the {value:type} matching syntax"""
    cleaned = TYPE_CLEANUP_REGEX.sub("(?:", regex)
    types[name] = Type(regex=cleaned, converter=converter)


# include some useful basic types
register_type("int", r"[+-]?[0-9]+", int)
register_type("float", r"[+-]?([0-9]*[.])?[0-9]+", float)
register_type("letters", r"[a-zA-Z]+")

# found on https://ihateregex.io/
register_type("bitcoin", r"(bc1|[13])[a-zA-HJ-NP-Z0-9]{25,39}")
register_type("email", r"[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+")
register_type("ssn", r"(?!0{3})(?!6{3})[0-8]\d{2}-(?!0{2})\d{2}-(?!0{4})\d{4}")
register_type(
    "ipv4",
    (
        r"(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]"
        r"?)){3}"
    ),
)
register_type(
    "url",
    (
        r"https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA"
        r"-Z0-9()!@:%_\+.~#?&\/\/=]*)"
    ),
)

register_type(
    # Visa, MasterCard, American Express, Diners Club, Discover, JCB
    "ccard",
    (
        r"(^4[0-9]{12}(?:[0-9]{3})?$)|(^(?:5[1-5][0-9]{2}|222[1-9]|22[3-9][0-9]|2[3-6]["
        r"0-9]{2}|27[01][0-9]|2720)[0-9]{12}$)|(3[47][0-9]{13})|(^3(?:0[0-5]|[68][0-9])"
        r"[0-9]{11}$)|(^6(?:011|5[0-9]{2})[0-9]{12}$)|(^(?:2131|1800|35\d{3})\d{11}$)"
    ),
)
register_type(
    "ipv6",
    (
        r"(([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA"
        r"-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){"
        r"1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3"
        r"}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0"
        r"-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:"
        r"(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5"
        r"]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0"
        r"-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,"
        r"3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))"
    ),
)


class Matcher:
    def __init__(self, pattern="*", case_sensitive=True):
        self.converters = {}
        self.pattern = pattern
        self.case_sensitive = case_sensitive
        self.regex = self._create_regex(pattern)

    def test(self, string):
        match = self._regex_compiled.match(string)
        return match is not None

    def match(self, string):
        match = self._regex_compiled.match(string)
        if match:
            # assemble result dict
            result = match.groupdict()
            for i, x in enumerate(self._grouplist(match)):
                result[i] = x

            # run converters
            for key, converter in self.converters.items():
                result[key] = converter(result[key])
            return result
        return None

    @property
    def regex(self):
        return self._regex

    @regex.setter
    def regex(self, value):
        self._regex = value
        flags = 0 if self.case_sensitive else re.IGNORECASE
        # cache the compiled regex
        self._regex_compiled = re.compile(value, flags=flags)

    def _field_repl(self, matchobj):
        # field with type annotation
        match = re.search(r"\{(\w+):(\w+)\}", matchobj.group(0))
        if match:
            name, type_ = match.groups()
            # register this field to convert it later
            self.converters[name] = types[type_].converter
            return r"(?P<%s>%s)" % (name, types[type_].regex)

        # field without type annotation
        match = re.search(r"\{(\w+)\}", matchobj.group(0))
        if match:
            name = match.group(1)
            return r"(?P<%s>.*)" % name

    def _create_regex(self, pattern):
        self.converters.clear()  # empty converters
        result = pattern.translate(SPECIAL_CHARS)  # escape special chars
        result = result.replace("*", r".*")  # handle wildcard
        result = re.sub(r"\{\}", r"(.*)", result)  # handle unnamed group
        result = re.sub(r"\{([^\}]*)\}", self._field_repl, result)  # handle named group
        return r"^%s$" % result

    @staticmethod
    def _grouplist(match):
        """extract unnamed match groups"""
        # https://stackoverflow.com/a/53385788/300783
        named = match.groupdict()
        ignored_groups = set()
        for name, index in match.re.groupindex.items():
            if name in named:  # check twice if it is really the named attribute
                ignored_groups.add(index)
        return [
            group
            for i, group in enumerate(match.groups())
            if i + 1 not in ignored_groups
        ]

    def __repr__(self):
        return '<Matcher("%s")>' % self.pattern


def test(pattern, string, case_sensitive=True):
    return Matcher(pattern, case_sensitive=case_sensitive).test(string)


def match(pattern, string, case_sensitive=True):
    return Matcher(pattern, case_sensitive=case_sensitive).match(string)


def to_regex(pattern):
    return Matcher(pattern).regex


def simplematch_cli():
    import json
    from argparse import ArgumentParser

    parser = ArgumentParser()
    parser.add_argument("pattern", help="A matching pattern")
    parser.add_argument("strings", help="The string to match", nargs="*")
    parser.add_argument(
        "--regex", action="store_true", help="Show the generated regular expression"
    )
    args = parser.parse_args()

    m = Matcher(args.pattern)
    if args.regex:
        print(f"Regex: {m.regex}")
    for string in args.strings:
        print(json.dumps(m.match(string)))


if __name__ == "__main__":
    simplematch_cli()