Alternative to foreach loop with hashes in perl - perl

Question

I have two files, one with text and another with key / hash values. I want to replace occurrences of the key with the hash values. The following code does this, what I want to know is if there is a better way than the foreach loop I am using.
Thanks all
Edit: I know it is a bit strange using
s/\n//;
s/\r//;
instead of chomp, but this works on files with mixed end of line characters (edited both on windows and linux) and chomp (I think) does not.
File with key / hash values (hash.tsv):
strict $tr|ct
warnings w#rn|ng5
here h3r3
File with text (doc.txt):
Do you like use warnings and strict?
I do not like use warnings and strict.
Do you like them here or there?
I do not like them here or there?
I do not like them anywhere.
I do not like use warnings and strict.
I will not obey your good coding practice edict.
The perl script:
#!/usr/bin/perl
use strict;
use warnings;
open (fh_hash, "<", "hash.tsv") or die "could not open file $!";
my %hash =();
while (<fh_hash>)
{
s/\n//;
s/\r//;
my #tmp_hash = split(/\t/);
$hash{ #tmp_hash[0] } = #tmp_hash[1];
}
close (fh_hash);
open (fh_in, "<", "doc.txt") or die "could not open file $!";
open (fh_out, ">", "doc.out") or die "could not open file $!";
while (<fh_in>)
{
foreach my $key ( keys %hash )
{
s/$key/$hash{$key}/g;
}
print fh_out;
}
close (fh_in);
close (fh_out);

Answer 1

One problem with
for my $key (keys %hash) {
s/$key/$hash{$key}/g;
}
is it doesn't correctly handle
foo => bar
bar => foo
Instead of swapping, you end up with all "foo" or all "bar", and you can't even control which.
# Do once, not once per line
my $pat = join '|', map quotemeta, keys %hash;
s/($pat)/$hash{$1}/g;
You might also want to handle
foo => bar
food => baz
by taking the longest rather than possibly ending with "bard".
# Do once, not once per line
my $pat =
join '|',
map quotemeta,
sort { length($b) <=> length($a) }
keys %hash;
s/($pat)/$hash{$1}/g;

Answer 2

You can read a whole file into a variable a replace all occurrences at once for each key-val.
Something like:
use strict;
use warnings;
use YAML;
use File::Slurp;
my $href = YAML::LoadFile("hash.yaml");
my $text = read_file("text.txt");
foreach (keys %$href) {
$text =~ s/$_/$href->{$_}/g;
}
open (my $fh_out, ">", "doc.out") or die "could not open file $!";
print $fh_out $text;
close $fh_out;
produces:
Do you like use w#rn|ng5 and $tr|ct?
I do not like use w#rn|ng5 and $tr|ct.
Do you like them h3r3 or th3r3?
I do not like them h3r3 or th3r3?
I do not like them anywh3r3.
I do not like use w#rn|ng5 and $tr|ct.
I will not obey your good coding practice edict.
For shorting a code i used YAML and replaced your input file with:
strict: $tr|ct
warnings: w#rn|ng5
here: h3r3
and used File::Slurp for reading a whole file into a variable. Of course, you can "slurp" the file without File::Slurp, for example with:
my $text;
{
local($/); #or undef $/;
open(my $fh, "<", $file ) or die "problem $!\n";
$text = <$fh>;
close $fh;
}