Regex de correspondência automática [fechado]

Escreva um regex não trivial que corresponda a si próprio.

Por exemplo, #.*$ corresponderá a um comentário fora de uma string em python até o final da linha e também se corresponderá na sintaxe perl regex.

Regras :

• A expressão regular deve fazer algo útil ou prático.
• Diga qual sintaxe do regex você está usando (por exemplo, perl ou POSIX).
• O vencedor é a resposta compatível com a votação mais alta.
• Seja criativo!

/(^|[^/])\/(?!\/)(\[.+?]|\\.|[^/\r\n])+\/[gim]{0,3}(?=\s*($|[\r\n,.;})]))/g

Roubado de https://github.com/LeaVerou/prism/blob/gh-pages/components/prism-javascript.js . Isso deve corresponder (em JavaScript) a todas as expressões regulares do JavaScript.

PITÃO

Abaixo está um gerador de regex auto-correspondente. Você fornece duas listas, uma contém dados de treinamento que a regex deve corresponder (além de corresponder a si mesma), a outra contém dados de treinamento que a regex NÃO deve corresponder:

from random import choice, randrange
import re
from itertools import zip_longest, chain, islice
from operator import itemgetter

CHAR_SET = [chr(i) for i in range(128)] + [r"\\", r"\d", r"\D",
                                           r"\w", r"\W", r"\s",
                                           r"\S", r"?:", r"\1",
                                           r"\2", r"\A", r"\b",
                                           r"\B", r"\Z", r"\.",
                                           r"\[", r"\]", r"\(",
                                           r"\)", r"\{", r"\}",
                                           r"\+", r"\|", r"\?",
                                           r"\*"]

CHAR_SAMPLE = []
BREAKPOINT = re.compile(
    r"""
    \(.*?\)|
    \[.*?\]|
    \{.*?\}|
    \w+(?=[\(\[\{])?|
    \S+?|
    \.\*\??|
    \.\+\??|
    \.\?\??|
    \\.|
    .*?
    """,
    re.VERBOSE)

MATCH_BRACKETS = {'(': ')', '[': ']', '{': '}'}
CLOSE_BRACKETS = {')', ']', '}'}
REGEX_SEEDER = [
    r".*?",
    r"(?:.*?)",
    r"\w|\s",
    r"(?<.*?)",
    r"(?=.*?)",
    r"(?!.*?)",
    r"(?<=.*?)",
    r"(?<!.*?)",
    ]

LEN_LIMIT = 100

def distribute(distribution):
    global CHAR_SAMPLE
    for item in CHAR_SET:
        if item in distribution:
            CHAR_SAMPLE.extend([item] * distribution[item])
        else:
            CHAR_SAMPLE.append(item)

def rand_index(seq, stop=None):
    if stop is None:
        stop = len(seq)
    try:
        return randrange(0, stop)
    except ValueError:
        return 0

def rand_slice(seq):
    try:
        start = randrange(0, len(seq))
        stop = randrange(start, len(seq))
        return slice(start, stop)
    except ValueError:
        return slice(0,  0)


#Mutation Functions

def replace(seq):
    seq[rand_index(seq)] = choice(CHAR_SAMPLE)

def delete(seq):
    del seq[rand_index(seq)]

def insert(seq):
    seq.insert(rand_index(seq, len(seq) + 1), choice(CHAR_SAMPLE))

def duplicate(seq):
    source = rand_slice(seq)
    seq[source.stop: source.stop] = seq[source]

def swap(seq):
    if len(seq) < 2: return
    a = rand_index(seq, len(seq) - 1)
    seq[a], seq[a + 1] = seq[a + 1], seq[a]

dummy = lambda seq: None

MUTATE = (
    replace,
    delete,
    insert,
    duplicate,
    swap,
    dummy,
    dummy,
    )

def repair_brackets(seq):
    """Attempts to lower the percentage of invalid regexes by
    matching orphaned brackets"""

    p_stack, new_seq = [], []
    for item in seq:
        if item in MATCH_BRACKETS:
            p_stack.append(item)
        elif item in CLOSE_BRACKETS:
            while p_stack and MATCH_BRACKETS[p_stack[-1]] != item:
                new_seq.append(MATCH_BRACKETS[p_stack[-1]])
                p_stack.pop()
            if not p_stack:
                continue
            else:
                p_stack.pop()
        new_seq.append(item)
    while p_stack:
        new_seq.append(MATCH_BRACKETS[p_stack.pop()])
    return new_seq

def compress(seq):
    new_seq = [seq[0]]
    last_match = seq[0]
    repeat = 1
    for item in islice(seq, 1, len(seq)):
        if item == last_match:
            repeat += 1
        else:
            if repeat > 1:
                new_seq.extend(list("{{{0}}}".format(repeat)))
            new_seq.append(item)
            last_match = item
            repeat = 1
    else:
        if repeat > 1:
            new_seq.extend(list("{{{0}}}".format(repeat)))
    return new_seq


def mutate(seq):
    """Random in-place mutation of sequence"""
    if len(seq) > LEN_LIMIT:
        seq[:] = seq[:LEN_LIMIT]
    c = choice(MUTATE)
    c(seq)

def crossover(seqA, seqB):
    """Recombination of two sequences at optimal breakpoints
    along each regex strand"""

    bpA = [item.start() for item in BREAKPOINT.finditer(''.join(seqA))]
    bpB = [item.start() for item in BREAKPOINT.finditer(''.join(seqA))]
    slObjA = (slice(*item) for item in zip(bpA, bpA[1:]))
    slObjB = (slice(*item) for item in zip(bpB, bpB[1:]))
    slices = zip_longest(
        (seqA[item] for item in slObjA),
        (seqB[item] for item in slObjB),
        fillvalue=[]
        )
    recombinant = (choice(item) for item in slices)
    return list(chain.from_iterable(recombinant))

#Fitness testing

def match_percentage(match):
    """Calculates the percentage a text actually matched
    by a regular expression"""

    if match and match.endpos:
        return (match.end() - match.start()) / match.endpos
    else:
        return 0.001

def fitness_test(seq, pos_matches, neg_matches):
    """Scoring algorithm to determine regex fitness"""

    try:
        self_str = ''.join(seq)
        regex = re.compile(self_str)
    except (re.error, IndexError):
        seq[:] = repair_brackets(seq)
        try:
            self_str = ''.join(seq)
            regex = re.compile(self_str)
        except (re.error, IndexError):
            return 0.001

    pos_score = sum(match_percentage(regex.search(item))
                    for item in pos_matches) / len(pos_matches) / 3

    neg_score = (1 - sum(match_percentage(regex.search(item))
                    for item in neg_matches) / len(neg_matches)) / 3

    self_score = match_percentage(regex.search(self_str)) / 3

    return pos_score + self_score + neg_score

#Population Management

def generate_pop(pos_matches, neg_matches, pop_size):
    sources = (pos_matches, REGEX_SEEDER)
    return [crossover(
        choice(choice(sources)), choice(choice(sources))
        ) for i in range(pop_size)]

def glean_pop(population, cutoff, fit_test, ft_args=()):
    scores = (fit_test(bug, *ft_args) for bug in population)
    ranked = sorted(zip(population, scores), key=itemgetter(1), reverse=True)
    maxItem = ranked[0]
    new_pop = next(zip(*ranked))[:cutoff]
    return maxItem, new_pop

def repopulate(population, pop_size):
    cutoff = len(population)
    for i in range(pop_size // cutoff):
        population.extend([crossover(choice(population), choice(population))
                           for i in range(cutoff)])
    population.extend([population[i][:] for i in range(pop_size - len(population))])

#Simulator
def simulate(pos_matches, neg_matches, pop_size=50, cutoff=10, threshold=1.0):
    population = generate_pop(pos_matches, neg_matches, pop_size)
    while True:
        for bug in population:
            mutate(bug)

        #Scoring step
        max_item, population = glean_pop(
            population,
            cutoff,
            fitness_test,
            (pos_matches, neg_matches)
            )

        #Exit condition:
        max_regex, max_score = max_item
        if max_score >= threshold:
            return max_score, max_regex
        """
        print(max_score, ''.join(max_regex))
        input("next?")"""

        #Repopulation Step:
        population = list(population)
        repopulate(population, pop_size)

Expressão regular JavaScript que corresponde a coisas assim.

/^\/\^\\\/\\\^[\\\[\]\/\^\${},\dd]{34}$/

Você pode testá-lo assim:

(function test() {
    var re =/^\/\^\\\/\\\^[\\\[\]\/\^\${},\dd]{34}$/;
    var m  =/=([^;]+)/.exec(test)[1];
    return re.exec(m);
})();