regular expression to match C function call over multiple lines - regex

Question

I am struggling to put together a regex to match a function call like following:
funcname (...(..
...)..(..(...
)...)..)
so the function can have multiple bracketed parameters spread over multiple lines.
The dots can be anything else appart from '(' or ')'.
I would use the regex with sed or grep.
Thanks,
Risto

Answer 1

So, I went on writing this simple parser in bash. It is not perfect but can serve as a starting point. For example it cannot distinguish if a function call is commented out or not, etc.
while read file; do
linenum=0
while IFS= read -r line; do
(( linenum++ ))
if [ $fmatch -eq 0 ]; then
if [[ ! $line =~ $funcname ]]; then
continue
fi
linenummatch=$linenum
fmatch=1
fstripped=0
openbracket=0
closebracket=0
spacenum=0
fi
linelen=${#line}
position=0
while [ $position -lt $linelen ]; do
if [ $fstripped -eq 0 ]; then
subline=${line:$position}
mlen=`expr "$subline" : "$funcname"`
if [ $mlen -gt 0 ]; then
(( position+=mlen ))
resultstr=$funcname
fstripped=1
continue
fi
(( position++ ))
continue
fi
ch=${line:$position:1}
case $ch in
'(' )
(( openbracket++ ))
spacenum=0
newresultstr="$resultstr$ch"
;;
')' )
if [ $openbracket -eq 0 ]; then
fmatch=0
break
fi
(( closebracket++ ))
spacenum=0
newresultstr="$resultstr$ch"
if [ $closebracket -eq $openbracket ]; then
echo "$file $linenummatch $newresultstr"
fmatch=0
break
fi
;;
' ' | '\t' )
if [ $spacenum -eq 0 ]; then
newresultstr=$resultstr' '
fi
(( spacenum++ ))
;;
'\n' )
# line feeds are skipped
;;
* )
if [ $openbracket -eq 0 ]; then
fmatch=0
break
fi
spacenum=0
newresultstr="$resultstr$ch"
;;
esac
resultstr=$newresultstr
(( position++ ))
done
done < $file
done < $filelist

Answer 2

As C is an irregular language you may need a parser for that. The problem you will have is working out when all the open brackets are closed again. You can do some fairly strange things with C. For example you can have a parameter that is a function definition in its own right. For example consider in the following program how you would distinguish between a(), b(), c(), d(), e(), f() and g()?
#include <stdio.h>
#define f(c) c;
char a()
{
return f('z');
}
/*
A function in a comment.
char b()
{
return 'y';
}
*/
char c(char d())
{
return d();
}
#if 0
This code is not included
char g()
{
return 'v';
}
#endif
void main()
{
printf ("A function in a string: char e() { return 'x'; }\n");
printf ("The result from passing a to c: %c\n", c(a));
printf ("Press enter to exit");
getchar();
}
I have seen many attempts to do this kind of thing with Regular Expressions but most of them end up with Catastrophic Backtracking issues.