Random Text generator based on regex [duplicate]

Answer 1

Check out the RandExp Ruby gem. It does what you want, though only in a limited fashion. (It won't work with every possible regexp, only regexps which meet some restrictions.)

Answer 2

Yes, there exists software that can generate a random match to a regex:

• Exrex, Python
• Pxeger, Javascript
• regex-genex, Haskell
• Xeger, Java
• Xeger, Python
• Generex, Java
• rxrdg, C#
• String::Random, Perl
• regldg, C
• paggern, PHP
• ReverseRegex, PHP
• randexp.js, Javascript
• EGRET, Python/C++
• MutRex, Java
• Fare, C#
• rstr, Python
• randexp, Ruby
• goregen, Go
• bfgex, Java
• regexgen, Javascript
• strgen, Python
• random-string, Java
• regexp-unfolder, Clojure
• string-random, Haskell
• rxrdg, C#
• Regexp::Genex, Perl
• StringGenerator, Python
• strrand, Go
• regen, Go
• Rex, C#
• regexp-examples, Ruby
• genex.js, JavaScript
• genex, Go

Answer 3

We did something similar in Python not too long ago for a RegEx game that we wrote. We had the constraint that the regex had to be randomly generated, and the selected words had to be real words. You can download the completed game EXE here, and the Python source code here.

Here is a snippet:

def generate_problem(level):
  keep_trying = True
  while(keep_trying):
    regex = gen_regex(level)
    # print 'regex = ' + regex
    counter = 0
    match = 0
    notmatch = 0
    goodwords = []
    badwords = []
    num_words = 2 + level * 3
    if num_words > 18:
      num_words = 18
    max_word_length = level + 4
    while (counter < 10000) and ((match < num_words) or (notmatch < num_words)):
      counter += 1
      rand_word = words[random.randint(0,max_word)]
      if len(rand_word) > max_word_length:
        continue
      mo = re.search(regex, rand_word)
      if mo:
        match += 1
        if len(goodwords) < num_words:
          goodwords.append(rand_word)
      else:
        notmatch += 1
        if len(badwords) < num_words:
          badwords.append(rand_word)
    if counter < 10000:
      new_prob = problem.problem()
      new_prob.title = 'Level ' + str(level)
      new_prob.explanation = 'This is a level %d puzzle. ' % level
      new_prob.goodwords = goodwords
      new_prob.badwords = badwords
      new_prob.regex = regex
      keep_trying = False
      return new_prob