在python中具有多个匹配和负面条件的多行正则表达式

Question

I am reading a text file and attempting to capture one of the arguments of each distinct tag, which has not been commented out.

More specifically, I have the following input...

maybe there is some text \THISTAG[arg1=1,argtwo]{WANT0}
% \THISTAG[arg1=1,argtwo]{NOTWANT}
% blah blah \THISTAG[arg1=1,argtwo]{NOTWANT}
\THISTAG[arg1=1,argtwo]{WANT1}\THISTAG[arg1=1,argtwo]{WANT2}\\stuff
\sometag{stuff I don't want}[{\THISTAG[arg1=1,argtwo]{WANT3}}]{more stuff I don't want}
\THISTAG[arg1=1,argtwo]{OBV_WANT}

I want the following output

WANT0
WANT1
WANT2
WANT3
OBV_WANT

So far I have the following code, which doesn't accomplish what I want

with open(target, "r") as ins:
    f = re.findall(r'^(?:[^%])?\\THISTAG\[.+\]{(.+?)}(?:{.+})?', ins.read(),re.MULTILINE)

Answer 1

You could do the regex line by line with filtering out the ones that start with % :

import re

res = []
with open('test.txt') as f:
    res = sum([re.findall('\\THISTAG\[.*?\]{(.*?)}', line) 
               for line in f if not line.startswith('%')
              ], [])

    print res # ['WANT0', 'WANT1', 'WANT2', 'WANT3', 'OBV_WANT']

Answer 2

Try this

^%.*|\\THISTAG[^{]+{([^}]+)}

Regex demo

Explanation:
^ : Start of string or start of line depending on multiline mode sample
. : Any character except line break sample
* : Zero or more times sample
| : Alternation / OR operand sample
\\ : Escapes a special character sample
[^x] : One character that is not x sample
+ : One or more sample
( … )`: Capturing group sample

import re
p = re.compile(ur'^%.*|\\THISTAG[^{]+{([^}]+)}', re.MULTILINE)
test_str = u"maybe there is some text \THISTAG[arg1=1,argtwo]{WANT0}\n% \THISTAG[arg1=1,argtwo]{NOTWANT}\n% blah blah \THISTAG[arg1=1,argtwo]{NOTWANT}\n\THISTAG[arg1=1,argtwo]{WANT1}\THISTAG[arg1=1,argtwo]{WANT2}\\stuff\n\sometag{stuff I don't want}[{\THISTAG[arg1=1,argtwo]{WANT3}}]{more stuff I don't want}\n\THISTAG[arg1=1,argtwo]{OBV_WANT}"

g = re.findall(p, test_str)
for m in g:
    if m:
        print m

Output:

WANT0
WANT1
WANT2
WANT3
OBV_WANT

Answer 3

So here's your regex shortened up a little bit:

re.findall(r'\\THISTAG\[.+?\]{([^N].+?)}', a,re.MULTILINE)

The important part is here:

{([^N].+?)}

Where I have [^N] is where you need to make your distinction between what you want and don't want. With the arguments you've given, I get this output:

>>> print(a)
\THISTAG[arg1=1,argtwo]{WANT0}
% \THISTAG[arg1=1,argtwo]{NOTWANT}
% blah blah \THISTAG[arg1=1,argtwo]{NOTWANT}
\THISTAG[arg1=1,argtwo]{WANT1}\THISTAG[arg1=1,argtwo]{WANT2}\stuff
\sometag{stuff I don't want}[{\THISTAG[arg1=1,argtwo]{WANT3}}]{more stuff I don'    t want}
\THISTAG[arg1=1,argtwo]{OBV_WANT}
>>>
>>> re.findall(r'\\THISTAG\[.+?\]{([^N].+?)}', a,re.MULTILINE)
['WANT0', 'WANT1', 'WANT2', 'WANT3', 'OBV_WANT']