| Description: |
Elaborating on my question Safely reading line by line, I have tried to put together a IO::Handle::getline variant with a size constraint on its return value.
It could be used like this:
my $fh = IO::File::Narrow->new('/path/to/file', 'r');
local $IO::File::Narrow::max_input_record_length = 80;
local $/ = "\n";
while (defined(my $line = $fh->getline)) {
# do something with line
}
It turns out supporting various flavours of $/ is not much fun.
I am not too fond of dynamically scoped variables either, but IO::* modules have them anyway. |
package IO::File::Narrow;
use 5.006001;
use strict;
use base qw(IO::File);
use Carp qw(croak);
our $VERSION = '0.01';
our $max_input_record_length = 1024;
sub getline {
@_ == 1 or croak 'usage: $io->getline()';
my $this = shift;
my $line = q{};
return undef if $this->eof;
my $irs = ref($this)->input_record_separator;
if (!defined $irs) {
while (defined(my $ch = $this->getc)) {
$line .= $ch;
croak 'input record too long'
if $max_input_record_length < length $line;
}
return $line;
}
if (ref $irs) {
my $frl = int(${$irs}) || 0;
while (defined(my $ch = $this->getc)) {
$line .= $ch;
croak 'input record too long'
if $max_input_record_length < length $line;
return $line if $frl == length $line;
}
return $line;
}
if (1 == length $irs) {
while (defined(my $ch = $this->getc)) {
$line .= $ch;
croak 'input record too long'
if $max_input_record_length < length $line;
return $line if $ch eq $irs;
}
return $line;
}
if (q{} ne $irs) {
while (defined(my $ch = $this->getc)) {
$line .= $ch;
croak 'input record too long'
if $max_input_record_length < length $line;
return $line if substr($line, -length $irs) eq $irs;
}
return $line;
}
else {
my $pch = q{};
while (defined(my $ch = $this->getc)) {
$line .= $ch;
croak 'input record too long'
if $max_input_record_length < length $line;
if ("\n" eq $ch && "\n" eq $pch) {
while (defined($ch = $this->getc)) {
if ("\n" ne $ch) {
$this->ungetc(ord $ch);
return $line;
}
}
return $line;
}
$pch = $ch;
}
return $line;
}
}
sub getlines {
@_ == 1 or croak 'usage: $io->getlines()';
wantarray or
croak 'Can\'t call $io->getlines in a scalar context, use $io-
+>getline';
my $this = shift;
my @buffer = ();
while (defined(my $line = $this->getline)) {
push @buffer, $line;
}
return @buffer;
}
1;
__END__
# TODO: pod documentation
|
