Convert dumb quotes to smart quotes in Python

dumb_to_smart_quotes.py

def dumb_to_smart_quotes(string):
    """Takes a string and returns it with dumb quotes, single and double,
    replaced by smart quotes. Accounts for the possibility of HTML tags
    within the string."""

    # Find dumb double quotes coming directly after letters or punctuation,
    # and replace them with right double quotes.
    string = re.sub(r'([a-zA-Z0-9.,?!;:\'\"])"', r'\1”', string)
    # Find any remaining dumb double quotes and replace them with
    # left double quotes.
    string = string.replace('"', '“')
    # Reverse: Find any SMART quotes that have been (mistakenly) placed around HTML
    # attributes (following =) and replace them with dumb quotes.
    string = re.sub(r'=“(.*?)”', r'="\1"', string)
    # Follow the same process with dumb/smart single quotes
    string = re.sub(r"([a-zA-Z0-9.,?!;:\"\'])'", r'\1’', string)
    string = string.replace("'", '‘')
    string = re.sub(r'=‘(.*?)’', r"='\1'", string)
    return string

Oops. If there is a slash at the end of a URL, the quotes get mixed up within the HTML tag.

<a href="http://url.com/" title="something">text</a> becomes
<a href="http://url.com/&#8220; title=&#8220;something">text</a>

Adding a slash after the colon in the search pattern in line 8 and 16 r'([a-zA-Z0-9.,?!;:/\'\"])"' seems to work. (But it probably breaks something else.)

I wrote a method to do the opposite, ignoring anything in an HTML tag: https://gist.github.com/dmdeluca/9cffec2edad3d9282dea534692f5b702

Might not be perfect, but it works.