regex to match the argument of specific functions

Question

how to write a regular expression to match the below string :

name(abc1) or number(param9) or listget(12jtxgh)

I want to match the string enclosed in brackets only if it is prepended by name or number or listget.

I tried to this : r'((.*?))'

and if my expression looks like below :

(name(foo) & number(bar)) - listget(baz)

then it starts matching (name(foo) also. I want my regex to extract only foo, bar and baz from the above expression as it is appended by name, number, listget.

I have to write regex in this form only #r'regex'

Try [`re.findall(r'\b\w+\(([^()]*)\)', s)`](https://regex101.com/r/z0flLh/2) — Wiktor Stribiżew, Feb 06 '18 at 20:50
As said, i can't use re.findall. I have to write anything between r' ' only — zubug55, Feb 06 '18 at 20:52
Excuse me, you have not mentioned such a requirement that you cannot use `re.findall`. Sure, you may use it in `re.finditer` to get all matches. What is your code, BTW? — Wiktor Stribiżew, Feb 06 '18 at 20:53
yes i mean prepended by sorry, also check the edits. The function name is not like func1 or func2 or func3. I have just given an example. My 3 fucntion names are fixed. — zubug55, Feb 06 '18 at 20:56
actually I am working with PLY, that's why i have to use specific format to define regular expressions. So, code is: def t_OP(t): r'&|-' return t def t_ID(t): r'\((.*?)\)' return t — zubug55, Feb 06 '18 at 21:00
@WiktorStribiżew so, as seen above, in all the functions i have first line as some regular expression — zubug55, Feb 06 '18 at 21:06

Robert Andrzejuk · Answer 1 · 2018-02-06T21:19:16.537

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In regex brackets are special symbols used for grouping. To match them you have to use an escape character \ like this \(.

For NOT matching a symbol ex. brackets:

[^)]

should be used. Where you don't need the escape character.

For finding an alternative you should use the pipe character | surrounded by brackets. Example:

 (mary|john)

For NOT catching a group in a result match inside the the brackets you should start with ?:

edited Feb 06 '18 at 21:19

answered Feb 06 '18 at 20:52

Robert Andrzejuk

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but how to check if it is prepended by those 3 function names only? – zubug55 Feb 06 '18 at 20:58
can you give the final regex? – zubug55 Feb 06 '18 at 21:02
You should be able to do it now but yourself, with the info I've written. Paste your example into https://regex101.com/ and see how it is matching. That is how I would have to do it for you. – Robert Andrzejuk Feb 06 '18 at 21:07

Tommaso Belluzzo · Accepted Answer · 2018-02-07T16:06:56.033

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The following regular expression should do the trick:

(?:listget|name|number)\(([^)]+)\)

You can try a working demo by visiting this link. As others pointed out, parenthesis must be escaped in order to match their literal, otherwise they are being used by the regex for different purposes (like capturing groups).

edited Feb 07 '18 at 16:06

answered Feb 06 '18 at 21:49

Tommaso Belluzzo

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Actually the parenthesis does not have to be escaped inside the brackets: 9.4.3 ERE Special Characters - "The period, left-bracket, backslash, and left-parenthesis shall be special except when used in a bracket expression ..." http://pubs.opengroup.org/onlinepubs/007904875/basedefs/xbd_chap09.html#tag_09_03_03 – Robert Andrzejuk Feb 07 '18 at 16:06

regex to match the argument of specific functions

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