Using Regular Expressions to expand contractions of a Word

replacers.py

import re

replacement_patterns = [
  (r'won\'t', 'will not'),
  (r'can\'t', 'cannot'),
  (r'i\'m', 'i am'),
  (r'ain\'t', 'is not'),
  (r'(\w+)\'ll', '\g<1> will'),
  (r'(\w+)n\'t', '\g<1> not'),
  (r'(\w+)\'ve', '\g<1> have'),
  (r'(\w+)\'s', '\g<1> is'),
  (r'(\w+)\'re', '\g<1> are'),
  (r'(\w+)\'d', '\g<1> would')
]


class RegexpReplacer(object):
  def __init__(self, patterns=replacement_patterns):
    self.patterns = [(re.compile(regex), repl) for (regex, repl) in patterns]
    
  def replace(self, text):
    s = text
    for (pattern, repl) in self.patterns:
      s = re.sub(pattern, repl, s)
    return s

Usage:

• create an instance of the class
  replacer = RegexpReplacer()
replacer.replace("can't is a contraction")

• output: "cannot is a contraction"

very good solution for contraction words in regular expressions.
Thank you.