How to replace the whole argument part of a C function call?

Question

I'm writing a bash script that aims to impact all the files in a folder, in order to replace all calls to a given C function by changing the argument. Here is what the current calls look like, and what I want to obtain :

myfunc( foo ) ----> myfunc( foo, foo+1 )

I use the following find/sed command and it does the job:

find . -name "*" -print | xargs sed -i 's/myfunc\([^)]*)\)/myfunc((\1),(\1)+1)/g'

But the issue arise when I have to deal with instructions/arguments that contains parentheses, like in the following instruction:

sqrt( myfunc( (foo+foo)*bar ) );

What happens is that the first closing parenthesis (i.e. the one after foo) is interpreted as the end of the myfunc argument, which it is not...

How can I get a regexp (or any other command) that capture and replace (foo+foo)*bar, i.e. exactly the content of the correct level of parentheses, whatever the number of parentheses levels ?

http://stackoverflow.com/questions/133601/can-regular-expressions-be-used-to-match-nested-patterns — John Zwinck, Sep 24 '14 at 07:44

score 1 · Answer 1 · answered Sep 24 '14 at 07:37

1

If you are sure your line will only contain myfunc( foo ) and there is no more ) afterwards, you can do a greedy search like this:

myfunc\((.*)\)

See example: http://regex101.com/r/gD1mN0/1

answered Sep 24 '14 at 07:37

Steven Xu

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will fail on something like `myfunc(1) + myfunc(2)` – NeronLeVelu Sep 24 '14 at 11:10

NeronLeVelu · Accepted Answer · 2014-09-25T08:59:51.727

sed ':a
s/myfunc(\([^(]\)(\([^)]*\))/myfunc(\1²\2³/
ta
s/myfunc(\([^)]*\))/myfunc(\1, (\1) + 1 )/g
y/²³/()/
'

Try this but it will fail (as is) on recursive call ( myfunc( 1 - myfunc( 2) ) ) on the second myfunc (normaly few use)) but will work on several myfunc (non inclusive) on the line.
assume the open and close () are on the same line as myfunc (sed works line per line by default)
posix version (--posixon GNU sed)
use of marker ²³ so assume not used in code, if any use other unused char or pre-modify and put it back after.

explaination

replace any peer of () after myfunc( by respectively ²³. (using recursive call to replace lower level per lower level). after the last substitution you have something like myfunc( subfunc2² subfunc3² arg31, arg32³, arg22³)
take the content between () where there is no more ( ) (oops, still could have ( ) in string so buggy on that case) inside and replace with content, content + 1
reset any ²³to repsectively ()

Remark: a first round to change (temporary modification with back to original at the end of operation) is needed for any ( or ) that are in string inside myfunc() [not very hard to do but annoying]

Thanks for the answer. Could you briefly explain the mechanism of the command? — Silverspur, Sep 25 '14 at 08:34

How to replace the whole argument part of a C function call?

2 Answers2