Python regex: matching a parenthesis within parenthesis

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Try this: 

import re
w = "TEMPLATES = ( ('index.html', 'home'), ('base.html', 'base'))"

# find outer parens
outer = re.compile("\((.+)\)")
m = outer.search(w)
inner_str = m.group(1)

# find inner pairs
innerre = re.compile("\('([^']+)', '([^']+)'\)")

results = innerre.findall(inner_str)
for x,y in results:
    print("%s <-> %s" % (x,y))

Output:

index.html <-> home
base.html <-> base

Explanation:

outer matches the first-starting group of parentheses using \( and \); by default search finds the longest match, giving us the outermost ( ) pair. The match m contains exactly what’s between those outer parentheses; its content corresponds to the .+ bit of outer.

innerre matches exactly one of your ('a', 'b') pairs, again using \( and \) to match the content parens in your input string, and using two groups inside the ' ' to match the strings inside of those single quotes.

Then, we use findall (rather than search or match) to get all matches for innerre (rather than just one). At this point results is a list of pairs, as demonstrated by the print loop.

Update: To match the whole thing, you could try something like this:

rx = re.compile("^TEMPLATES = \(.+\)")
rx.match(w)

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