Finding function calls using regex

Question

I'm trying to detect functions between call-chains.

For example, I can use

re.search("([\w_]+)\((|[\W\d\w\,]+)\)", line)

to find

print(len("AA"))

but it is reasonably not compatible with code like:

print(i + len("AA") + j + len("BBB"))

Help me.

first, it's not a good idea to parse nested function calls with regex, since the language is not regular. second, you can use the ast modul to analyse python code — gefei
– gefei, Commented Oct 7, 2013 at 8:14
Maybe a profiler would help here to see a caller graph, e.g.: pydoc -k profile. BTW: "Help me." sounds a bit rude, "Please help me." would be more polite, but both are not needed here at SX. — math
– math, Commented Oct 7, 2013 at 11:52

chthonicdaemon · Accepted Answer · 2013-10-07 11:11:42Z

1

Your needs may be better served by the ast module:

import ast

a = ast.parse('print(i + len("AA") + j + len("BBB"))')
print ast.dump(a)

>>>
Module(body=[Print(dest=None, values=[BinOp(left=BinOp(left=BinOp(left=Name(id='i',
ctx=Load()), op=Add(), right=Call(func=Name(id='len', ctx=Load()), args=[Str(s='AA')], 
keywords=[], starargs=None, kwargs=None)), op=Add(), right=Name(id='j', ctx=Load())), 
op=Add(), right=Call(func=Name(id='len', ctx=Load()), args=[Str(s='BBB')], keywords=[], 
starargs=None, kwargs=None))], nl=True)])

edited Oct 7, 2013 at 11:11

answered Oct 7, 2013 at 8:29

chthonicdaemon

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Bohemian · Accepted Answer · 2014-03-27 12:04:18Z

0

Use this regex:

(\w+)\(((?:[^()]*\([^()]*\))*[^()]*)\)

This captures the name of the function in group 1, and the contents the brackets (the parameters) in group 2.

See a live demo of this regex working with your examples.

BTW, Your regex could use some attention:

[\w_]+ is equivalent to just \w+ because \w includes underscore
[\W\d\w\,] is equivalent to just ., because the combination \W\w (everything not a word char and every word char) includes everything

edited Mar 27, 2014 at 12:04

answered Oct 7, 2013 at 12:32

Bohemian♦

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