Perl regex replacement in file skips newlines - regex

Question

I am currently trying to format text for use with pandoc, but my regex replacement isn't working.
Here is my code so far:
#Importing the file
my $filename = 'example.md';
my $file = path($filename);
my $data = $file ->slurp_utf8;
#Placing code blocks into an array and replacing them in the file
my #code_block_values;
my $i = 0;
while($i > 50) {
#code_bock_values[$i] = ($data =~ /\n\t*```[^`]+(```){1}\n/);
$data =~ s/\n\t*```[^`]+(```){1}\n/(code_block)/;
$i = $i + 1;
}
#Replacing the code blocks
$i = 0;
while($i < 50) {
$data =~ s/\(code_block\)/$code_block_values[$i]/;
$i = $i + 1;
}
print $data;
$file->spew_utf8( $data );
I realize that this probably isn't the most efficient way to be doing this, but right now I'm just trying to get it working.
Basically, I am using github-flavored markdown for typing up my notes, and then trying to convert it with pandoc to a pdf file. I am doing some other formatting before-hand, but I have to extract the code blocks first (which are deliniated by triple backticks (```).)
The following is a sample code block that would be a code block:
```bash
#!/bin/bash
echo "Enter a number"
read count
if [ $count -eq 100 ]
then
echo "Example-3: Count is 100"
elif [ $count -gt 100 ]
then
echo "Example-3: Count is greater than 100"
else
echo "Example-3: Count is less than 100"
fi
```
As far as I can tell, the regex is capturing everything that I need (as tested by an online regex tester), but Perl is only inserting newlines at certain points, specifically newlines followed by a tab.
The previous example translates to:
```bash #!/bin/bash echo "Enter a number" read count if [ $count -eq 100 ] then
echo "Example-3: Count is 100" elif [ $count -gt 100 ] then
echo "Example-3: Count is greater than 100" else
echo "Example-3: Count is less than 100" fi
```
As you can see, the tabs are also completely removed. I copied over all of the file contents from atom and the different lengths of tabs are as copied over from the editor (not sure that makes a difference.) I did my editing for the shell script in vim but the editing for the notes in atom itself.
I am new to Perl, so any help would be appreciated.

Answer 1

My guess:
#!/usr/bin/perl
use strict;
use warnings;
# Slurps DATA after __END__ into a scalar
my $data = do { local $/; <DATA> };
my #code_block_values;
# Extract and replace code blocks with '(code_block)'
while ($data =~ s/ (``` .*? ```) /(code_block)/xs) {
push #code_block_values, $1;
}
printf "\n--| Replaced:\n%s", $data;
# Restore '(code_block)' with actual content
$data =~ s/ \(code_block\) / shift #code_block_values /xge;
printf "\n--| Restored:\n%s", $data;
__END__
```bash
#!/bin/bash
echo "Enter a number"
read count
if [ $count -eq 100 ]
then
echo "Example-3: Count is 100"
elif [ $count -gt 100 ]
then
echo "Example-3: Count is greater than 100"
else
echo "Example-3: Count is less than 100"
fi
```
```perl
#!/usr/bin/perl
print "Hello World\n";
```
Output:
--| Replaced:
(code_block)
(code_block)
--| Restored:
```bash
#!/bin/bash
echo "Enter a number"
read count
if [ $count -eq 100 ]
then
echo "Example-3: Count is 100"
elif [ $count -gt 100 ]
then
echo "Example-3: Count is greater than 100"
else
echo "Example-3: Count is less than 100"
fi
```
```perl
#!/usr/bin/perl
print "Hello World\n";
```
If you want to learn more about Perl's regular expressions, perlre and perlretut is a good read.