perl - extracting function arguments from multi line function definitions - regex

Question

eErrorT ChainCtrlInitChains(ChainCtrlT* pChainCtrl,
char* name,
int instance)
{
....
}
eErrorT ChainCtrlInit(ChainCtrlT* pChainCtrl, void* pOwner)
{
....
}
MY CODE
open(my $FILE, "< a.c") or die $!;
my #arr = <$FILE>;
foreach(#arr){
if ($_ =~ /^ \S+ \s+ \S+ \s* \( (.+?) \) /xsmg) {
my $arg = $1;
my #arr = map /(\w+)$/, split /\W*?,\W*/, $arg;
print my #temp = map "$_\n", #arr
unless $_ =~ /;\s*$/;
}
}
Basically I am extracting function arguments from the function definitions.
But in this case I am only able to extract arguments for 2nd function(ChainCtrlInit) and not for 1st function(ChainCtrlinitchains).
DESIRED OUTPUT
pChainCtrl
name
instance
pChainCtrl
pOwner
OUTPUT I AM GETTING
pChainCtrl
pOwner

Answer 1

The problem you have is when you do "foreach", $_ in the block inherits each element in the array.
For example,
foreach(#arr).. the first iteration of the loop assign $_ with "eErrorT ChainCtrlInitChains(ChainCtrlT* pChainCtrl,\n", so your regex will fail.
And you also use temp variables that don't have too much use. I have improved the code as the following:
my $arr = do { local $/; <$FILE> }; #Copy one of the comments above.
#note there's a slight difference in the 'while' regex to your code
while ($arr =~ /^ \S+ \s+ \S+ \s* (\( .+? \)) /xsmg) {
my #args = $1 =~ /(\w+)[,)]/g; #This assumes what you want always ends in
#a ',' or a ')', hence the gentle modification in the 'while' regex.
local $" = "\n";
say "#args";
}

Answer 2

The problem is that you are reading the file line by line and so the regex can never extend across multiple lines - if you load the file then make it a single string with embedded new lines it will work
eg a quick hack gives
open(my $FILE, "< a.c") or die $!;
my #arr = <$FILE>;
my $file = join('',#arr);
my #matches = $file =~ /^ \S+ \s+ \S+ \s* \( (.+?) \) /xsmg;
foreach (#matches) {
my $arg = $_;
my #arr = map /(\w+)$/, split /\W*?,\W*/, $arg;
print my #temp = map "$_\n", #arr
unless $_ =~ /;\s*$/;
print "\n";
}

Answer 3

#Ad-vic, in addition to #atleypnorth's solution to slurp the whole file into a string, there could be a problem within your split-map statement.
this
my #arr = map /(\w+)$/, split /\W*?,\W*/, $arg;
should be this
my #arr = map /(\w+)\W*$/, split /\W*?,\W*/, $arg;
because the last element from split gets residual characters.
Once you get the hang of Perl, you could streamline it into this -
$/ = "";
open(my $FILE, "< a.c") or die $!;
my $str = <$FILE>;
foreach ( $str =~ /^ \S+ \s+ \S+ \s* \( (.+?) \) /xsmg ) {
print map "$_\n", /(\w+) [^\w,]* (?:,|$)/xg ;
print "\n";
}