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|
use strict;
BEGIN{ if (not $] < 5.006) { require warnings; warnings->import } }
package Tie::Handle::Offset;
# ABSTRACT: Tied handle that hides the beginning of a file
our $VERSION = '0.004';
use Tie::Handle;
our @ISA = qw/Tie::Handle/;
#--------------------------------------------------------------------------#
# Glob slot accessor
#--------------------------------------------------------------------------#
sub offset {
my $self = shift;
if ( @_ ) {
return ${*$self}{offset} = shift;
}
else {
return ${*$self}{offset};
}
}
#--------------------------------------------------------------------------#
# Tied handle methods
#--------------------------------------------------------------------------#
sub TIEHANDLE
{
my $class = shift;
my $params;
$params = pop if ref $_[-1] eq 'HASH';
my $self = \do { no warnings 'once'; local *HANDLE};
bless $self,$class;
$self->OPEN(@_) if (@_);
if ( $params->{offset} ) {
seek( $self, $self->offset( $params->{offset} ), 0 );
}
return $self;
}
sub TELL {
my $cur = tell($_[0]) - $_[0]->offset;
# XXX shouldn't ever be less than zero, but just in case...
return $cur > 0 ? $cur : 0;
}
sub SEEK {
my ($self, $pos, $whence) = @_;
my $rc;
if ( $whence == 0 || $whence == 1 ) { # pos from start, cur
$rc = seek($self, $pos + $self->offset, $whence);
}
elsif ( _size($self) + $pos < $self->offset ) { # from end
$rc = '';
}
else {
$rc = seek($self,$pos,$whence);
}
return $rc;
}
sub OPEN
{
$_[0]->offset(0);
$_[0]->CLOSE if defined($_[0]->FILENO);
@_ == 2 ? open($_[0], $_[1]) : open($_[0], $_[1], $_[2]);
}
sub _size {
my ($self) = @_;
my $cur = tell($self);
seek($self,0,2); # end
my $size = tell($self);
seek($self,$cur,0); # reset
return $size;
}
#--------------------------------------------------------------------------#
# Methods copied from Tie::StdHandle to avoid dependency on Perl 5.8.9/5.10.0
#--------------------------------------------------------------------------#
sub EOF { eof($_[0]) }
sub FILENO { fileno($_[0]) }
sub CLOSE { close($_[0]) }
sub BINMODE { binmode($_[0]) }
sub READ { read($_[0],$_[1],$_[2]) }
sub READLINE { my $fh = $_[0]; <$fh> }
sub GETC { getc($_[0]) }
sub WRITE
{
my $fh = $_[0];
print $fh substr($_[1],0,$_[2])
}
1;
# vim: ts=2 sts=2 sw=2 et:
__END__
=pod
=encoding UTF-8
=head1 NAME
Tie::Handle::Offset - Tied handle that hides the beginning of a file
=head1 VERSION
version 0.004
=head1 SYNOPSIS
use Tie::Handle::Offset;
tie *FH, 'Tie::Handle::Offset', "<", $filename, { offset => 20 };
=head1 DESCRIPTION
This modules provides a file handle that hides the beginning of a file.
After opening, the file is positioned at the offset location. C<seek()> and
C<tell()> calls are modified to preserve the offset.
For example, C<tell($fh)> will return 0, though the actual file position
is at the offset. Likewise, C<seek($fh,80,0)> will seek to 80 bytes from
the offset instead of 80 bytes from the actual start of the file.
=for Pod::Coverage method_names_here
=for :stopwords cpan testmatrix url annocpan anno bugtracker rt cpants kwalitee diff irc mailto metadata placeholders metacpan
=head1 SUPPORT
=head2 Bugs / Feature Requests
Please report any bugs or feature requests through the issue tracker
at L<https://github.com/dagolden/tie-handle-offset/issues>.
You will be notified automatically of any progress on your issue.
=head2 Source Code
This is open source software. The code repository is available for
public review and contribution under the terms of the license.
L<https://github.com/dagolden/tie-handle-offset>
git clone https://github.com/dagolden/tie-handle-offset.git
=head1 AUTHOR
David Golden <dagolden@cpan.org>
=head1 COPYRIGHT AND LICENSE
This software is Copyright (c) 2012 by David Golden.
This is free software, licensed under:
The Apache License, Version 2.0, January 2004
=cut
|
