Last active
February 18, 2022 12:39
-
-
Save fitoprincipe/10f76e266ae9c52c26858d69fc84e4c0 to your computer and use it in GitHub Desktop.
match format string
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
def match_format_string(format_str, s): | |
""" https://stackoverflow.com/questions/10663093/use-python-format-string-in-reverse-for-parsing | |
Match s against the given format string, return dict of matches. | |
We assume all of the arguments in format string are named keyword arguments (i.e. no {} or | |
{:0.2f}). We also assume that all chars are allowed in each keyword argument, so separators | |
need to be present which aren't present in the keyword arguments (i.e. '{one}{two}' won't work | |
reliably as a format string but '{one}-{two}' will if the hyphen isn't used in {one} or {two}). | |
We raise if the format string does not match s. | |
Example: | |
fs = '{test}-{flight}-{go}' | |
s = fs.format(test='first', flight='second', go='third') | |
match_format_string(fs, s) -> {'test': 'first', 'flight': 'second', 'go': 'third'} | |
""" | |
# First split on any keyword arguments, note that the names of keyword arguments will be in the | |
# 1st, 3rd, ... positions in this list | |
tokens = re.split(r'\{(.*?)\}', format_str) | |
keywords = tokens[1::2] | |
# Now replace keyword arguments with named groups matching them. We also escape between keyword | |
# arguments so we support meta-characters there. Re-join tokens to form our regexp pattern | |
tokens[1::2] = map(u'(?P<{}>.*)'.format, keywords) | |
tokens[0::2] = map(re.escape, tokens[0::2]) | |
pattern = ''.join(tokens) | |
# Use our pattern to match the given string, raise if it doesn't match | |
matches = re.match(pattern, s) | |
if not matches: | |
raise Exception("Format string did not match") | |
# Return a dict with all of our keywords and their values | |
return {x: matches.group(x) for x in keywords} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
This is a very useful code that I find myself using in many project. So I share ;)