Perl Array of regular expressions -- matching elements of an array - arrays

Question

I am trying to match and remove elements from an array called #array. The elements to be removed must match the patterns stored inside an array called #del_pattern
my #del_pattern = ('input', 'output', 'wire', 'reg', '\b;\b', '\b,\b');
my #array = (['input', 'port_a', ','],
['output', '[31:0]', 'port_b,', 'port_c', ',']);
To remove the patterns contained in #del_pattern from #array, I loop through all the elements in #del_pattern and exclude them using grep.
## delete the patterns found in #del_pattern array
foreach $item (#del_pattern) {
foreach $i (#array) {
#$i = grep(!/$item/, #$i);
}
}
However, I have been unable to remove ',' from #array. If I use ',' instead of '\b,\b' in #del_pattern, element port_b, gets removed from the #array as well, which is not an intended outcome. I am only interested in removing elements that contain only ','.

Answer 1

You are using the wrong regular expression. I updated the code and tried it and its working fine. PFB the update code:
my #del_pattern = ('input', 'output', 'wire', 'reg', '\b;\b', '^,$');
my #array = (['input', 'port_a', ','],
['output', '[31:0]', 'port_b,', 'port_c', ',']);
## delete the patterns found in #del_pattern array
foreach my $item (#del_pattern) {
foreach my $i (#array) {
#$i = grep(!/$item/, #$i);
}
}
The only change made is in the Regex '\b,\b' to '^,$'. I don't have much info on \b but the regex I am suggesting is doing what you intend.

Answer 2

You want
^,\z
An explanation of what \b doesn't match at all follows.
\b
defines the boundary of a "word". It is equivalent to
(?<=\w)(?!\w) | (?<!\w)(?=\w)
so
\b,\b
is equivalent to
(?: (?<=\w)(?!\w) | (?<!\w)(?=\w) ) , (?: (?<=\w)(?!\w) | (?<!\w)(?=\w) )
Since comma is a non-word character, that simplifies to
(?<=\w),(?=\w)
So
'a,b' =~ /\b,\b/ # Match
',' =~ /\b,\b/ # No match

Answer 3

This works, but not very nice from the code.
This code snippet also removes the ','
my $elm = [];
sub extract {
my $elm = shift;
foreach my $del (#del_pattern) {
$elm =~ s/$del//g;
if ( $elm ) {
return $elm;
}
}
}
foreach my $item (#array) {
foreach my $i (#$item) {
my $extract = extract($i);
if ($extract) {
push(#$elm, $extract);
}
}
}
print Dumper($elm);
Why your #array has array? Why not one big array?