perl expression find & replace to modify an external function definition - perl

Question

Is it possible to use perl to remove parameters from a function definition? eg if my file contains the following text:
var1 = myfunc(sss,'ROW DRILL',1,1,0);
var2 = myfunc(fff,'COL DRILL',1,1,0);
var3 = myfunc(anyAlphaNum123,'anyAlphaNum123 or space',1,1,0);
donotcapture=myfunc2(rr,'some string',1,1,0);
I need to change it so that it becomes:
var1 = myfunc(sss,'ROW DRILL');
var2 = myfunc(fff,'COL DRILL');
var3 = myfunc(anyAlphaNum123,'anyAlphaNum123 or space');
donotcapture=myfunc2(rr,'some string',1,1,0);
Essentially just removing ,1,1,0 from all instances where myfunc is called, but preserving the first two parameters.
I have tried the following, but this approach would mean I have to write rules for each permutation...
perl -pi -w -e "s/myfunc\(rr,'COL SUBSET',1,1,0\)/myfunc\(rr,'COL SUBSET'\)/g;" *.txt

Answer 1

In order to reduce complexity, generalize your regex, using flexible regexes.
The regex for "anything between ( and ,, except , " : \(([^,]+),
The regex for "anything between ' and ', except ' " : \'([^']+)\'
In order to get the output right for the specific input (in spite of the flexibility),
use capture groups, i.e. (...).
They populate variables, which you can use as $1 in the substitution.
To prevent matching functions with names ending in your functions name, e.g. notmyfunc(),
use the regex for word boundary, i.e. \b.
Ikegamis edit (separated to keep visible what you and I learned the hard way):
Avoid double-quotes for the program argument.
It's just asking for trouble and requires so much extra escaping.
Note that \x27 is a single quote when used inside double-quotes or regex literals.
\' -> \x27
Only use one capture group (myfunc\([^,]+,\x27[^\x27]+\x27)
Remove the ;, which is not needed for a single statement.
Add a . to the input file wildcard, assuming you actually meant it like that.
Working code
(Comparing to chat note the \((; the backslash got lost, eaten by the chat I believe.):
perl -pi -w -e "s/(\bmyfunc)\(([^,]+),\'([^']+)\'(?:,\d+){3}\)/\$1\(\$2,\'\$3\'\)/g;" *txt
Ikegamis nice edit
(The detail which was so time-consuming in our chat is not easily visible anymore,
because the ( for the capture group was moved somewhere else.):
perl -i -wpe's/\b(myfunc\([^,]+,\x27[^\x27]+\x27)(?:,\d+){3}\)/$1)/g' *.txt
Input:
var1 = myfunc(sss,'ROW DRILL',1,1,0);
var2 = myfunc(fff,'COL DRILL',1,1,0);
var3 = myfunc(s,'ROW SUBSET',1,1,0);
var4 = myfunc(rr,'COL SUBSET',1,1,0);
var5 = myfunc(rr,'COL SUBSET',2,12,50); with different values
var6 = notmyfunc(rr,'COL SUBSET',1,1,0); tricky differet name
var1 = myfunc(sss,'ROW DRILL',1,1,0);
var2 = myfunc(fff,'COL DRILL',1,1,0);
var3 = myfunc(anyAlphaNum123,'anyAlphaNum123 or space',1,1,0);
donotcapture=myfunc2(rr,'some string',1,1,0);
Output (version "even more relaxed"):
var1 = myfunc(sss,'ROW DRILL');
var2 = myfunc(fff,'COL DRILL');
var3 = myfunc(s,'ROW SUBSET');
var4 = myfunc(rr,'COL SUBSET');
var5 = myfunc(rr,'COL SUBSET'); with different values
var6 = notmyfunc(rr,'COL SUBSET',1,1,0); tricky differet name
var1 = myfunc(sss,'ROW DRILL');
var2 = myfunc(fff,'COL DRILL');
var3 = myfunc(anyAlphaNum123,'anyAlphaNum123 or space');
donotcapture=myfunc2(rr,'some string',1,1,0);
Lessons learned:
I made a habit of creating regexes as tightly fitting the input as possible.
But that caught us/me unprepared, when applied to sample input by someone inexperienced with regexes. (Absolutely no blame on you.)
Posting code-quotes into chat is dangerous, be careful with \.