python regex to parse key value pairs with multiple lines in the value

Question

I am trying to parse a file that has multiple key, value lines as show below

"key1" = "value1";
"key2" = "value2";
"key3" = "value3_line1
value3_line2
value3_line3";
"key4" = "value4";

I am using below code to parse this file

def parseFile(f):
    regex = re.compile(r'^"(.*)"\s+=\s+"(.*)";',re.MULTILINE)
    with open(f) as string_file:
        alllines = string_file.read()
        matches = [m.groups() for m in regex.finditer(alllines)]
        for m in matches:
            print(m[0], '=>', m[1])

This code matches for lines with key1, key2 and key4 but doesn't match key3. How do i fix this to get all key values pairs including those that has multiline values?

regex = re.compile(r'^"(.*)"\s+=\s+"(.*)"?;?',re.MULTILINE) ? — Rakesh
– Rakesh, Commented Oct 3, 2018 at 10:30

blhsing · Accepted Answer · 2018-10-03 10:38:00Z

1

You can use the re.DOTALL flag, which allows . to match newline characters. You should also use non-greedy quantifier *? to match the nearest pairs of double quotes:

Change:

regex = re.compile(r'^"(.*)"\s+=\s+"(.*)";',re.MULTILINE)

to:

regex = re.compile(r'^"(.*?)"\s+=\s+"(.*?)";',re.MULTILINE | re.DOTALL)

Alternatively, you can use a character class that excludes ":

regex = re.compile(r'^"([^"]*)"\s+=\s+"([^"]*)";',re.MULTILINE)

edited Oct 3, 2018 at 10:38

answered Oct 3, 2018 at 10:31

blhsing

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2 Comments

Jaydeep Kulkarni Over a year ago

That did a greedy match.. it took all lines till "key4" as the key and "value4" as a the value. How do make it match the 1st ';' instead of last?

Jaydeep Kulkarni Over a year ago

My bad. I didn't see you had added '?' in the regex. That did the trick. Thanks for the quick respond and perfect answer.

Rakesh · Accepted Answer · 2018-10-03 10:36:26Z

0

It is not matching "key3" because the line is missing a quote and a semi-colon.

Try pattern re.compile(r'^"(.*)"\s+=\s+"(.*)"?;?',re.MULTILINE) or re.compile(r'^"(.*)"\s+=\s+"(.*)$',re.MULTILINE)

Ex:

import re

s = '''"key1" = "value1";
"key2" = "value2";
"key3" = "value3_line1
value3_line2
value3_line3";
"key4" = "value4";'''

regex = re.compile(r'^"(.*)"\s+=\s+"(.*)"?;?',re.MULTILINE) 
matches = [m.groups() for m in regex.finditer(s)]
for m in matches:
    print(m[0], '=>', m[1])

Output:

('key1', '=>', 'value1";')
('key2', '=>', 'value2";')
('key3', '=>', 'value3_line1')
('key4', '=>', 'value4";')

answered Oct 3, 2018 at 10:36

Rakesh

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