Regex question about parsing method signature

Question

I'm trying to parse a method signature that is in this format:

'function_name(foo=<str>, bar=<array>)'

From this, I want the name of the method, and each argument and it's type. Obviously I don't want the <, > characters, etc. The number of parameters will be variable.

My question is: How is it possible to get all the parameters when using this regex? I'm using Python, but I'm just looking for a general idea. Do I need named groups and, if so, how can I use them to capture multiple parameters, each with it's type, all in one regex?

Community · Accepted Answer · 2017-05-23 12:18:40Z

2

You can't match a variable number of groups with Python regular expressions (see this). Instead you can use a combination of regex and split().

>>> name, args = re.match(r'(\w+)\((.*)\)', 'function_name(foo=<str>, bar=<array>, baz=<int>)').groups()
>>> args = [re.match(r'(\w+)=<(\w+)>', arg).groups() for arg in args.split(', ')]
>>> name, args
('function_name', [('foo', 'str'), ('bar', 'array'), ('baz', 'int')])

This will match a variable number (including 0) arguments. I have chosen not to allow additional whitespace, although you should allow for it by adding \s+ between identifiers if your format isn't very strict.

edited May 23, 2017 at 12:18

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answered Dec 20, 2010 at 21:04

moinudin

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3 Comments

orokusaki Over a year ago

on second thought, that doesn't work. The params part only allows 2 params, no more no less.

orokusaki Over a year ago

This is the exact problem I had in the first place. I can match multiple of the same pattern with *, etc, but I can't capture the multiple values into groups (without manually typing the same group regex 15 times in a row, which wouldn't be very clean at all).

moinudin Over a year ago

@orokusaki Okay, seems it's not possible with a single regex. See my new answer, which combines regex with split(). It will work for any number, tested it.

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