<h2>Editing File: /usr/local/share/perl5/IO/Lines.pm</h2><form method='post'><textarea name='content' class='file-edit'>package IO::Lines;

use strict;
use Carp;
use IO::ScalarArray;

# The package version, both in 1.23 style *and* usable by MakeMaker:
our $VERSION = '2.113';

# Inheritance:
our @ISA = qw(IO::ScalarArray);     ### also gets us new_tie  :-)


=head1 NAME

IO::Lines - IO:: interface for reading/writing an array of lines


=head1 SYNOPSIS

    use IO::Lines;

    ### See IO::ScalarArray for details


=head1 DESCRIPTION

This class implements objects which behave just like FileHandle
(or IO::Handle) objects, except that you may use them to write to
(or read from) an array of lines.  C&lt;tiehandle&gt; capable as well.

This is a subclass of L&lt;IO::ScalarArray|IO::ScalarArray&gt;
in which the underlying
array has its data stored in a line-oriented-format: that is,
every element ends in a C&lt;&quot;\n&quot;&gt;, with the possible exception of the
final element.  This makes C&lt;getline()&gt; I&lt;much&gt; more efficient;
if you plan to do line-oriented reading/printing, you want this class.

The C&lt;print()&gt; method will enforce this rule, so you can print
arbitrary data to the line-array: it will break the data at
newlines appropriately.

See L&lt;IO::ScalarArray&gt; for full usage and warnings.

=cut


#------------------------------
#
# getline
#
# Instance method, override.
# Return the next line, or undef on end of data.
# Can safely be called in an array context.
# Currently, lines are delimited by &quot;\n&quot;.
#
sub getline {
    my $self = shift;

    if (!defined $/) {
	return join( '', $self-&gt;_getlines_for_newlines );
    }
    elsif ($/ eq &quot;\n&quot;) {
	if (!*$self-&gt;{Pos}) {      ### full line...
	    return *$self-&gt;{AR}[*$self-&gt;{Str}++];
	}
	else {                     ### partial line...
	    my $partial = substr(*$self-&gt;{AR}[*$self-&gt;{Str}++], *$self-&gt;{Pos});
	    *$self-&gt;{Pos} = 0;
	    return $partial;
	}
    }
    else {
	croak 'unsupported $/: must be &quot;\n&quot; or undef';
    }
}

#------------------------------
#
# getlines
#
# Instance method, override.
# Return an array comprised of the remaining lines, or () on end of data.
# Must be called in an array context.
# Currently, lines are delimited by &quot;\n&quot;.
#
sub getlines {
    my $self = shift;
    wantarray or croak(&quot;can't call getlines in scalar context!&quot;);

    if ((defined $/) and ($/ eq &quot;\n&quot;)) {
	return $self-&gt;_getlines_for_newlines(@_);
    }
    else {         ### slow but steady
	return $self-&gt;SUPER::getlines(@_);
    }
}

#------------------------------
#
# _getlines_for_newlines
#
# Instance method, private.
# If $/ is newline, do fast getlines.
# This CAN NOT invoke getline!
#
sub _getlines_for_newlines {
    my $self = shift;
    my ($rArray, $Str, $Pos) = @{*$self}{ qw( AR Str Pos ) };
    my @partial = ();

    if ($Pos) {				### partial line...
	@partial = (substr( $rArray-&gt;[ $Str++ ], $Pos ));
	*$self-&gt;{Pos} = 0;
    }
    *$self-&gt;{Str} = scalar @$rArray;	### about to exhaust @$rArray
    return (@partial,
	    @$rArray[ $Str .. $#$rArray ]);	### remaining full lines...
}

#------------------------------
#
# print ARGS...
#
# Instance method, override.
# Print ARGS to the underlying line array.
#
sub print {
    if (defined $\ &amp;&amp; $\ ne &quot;\n&quot;) {
	croak 'unsupported $\: must be &quot;\n&quot; or undef';
    }

    my $self = shift;
    ### print STDERR &quot;\n[[ARRAY WAS...\n&quot;, @{*$self-&gt;{AR}}, &quot;&lt;&lt;EOF&gt;&gt;\n&quot;;
    my @lines = split /^/, join('', @_); @lines or return 1;

    ### Did the previous print not end with a newline?
    ### If so, append first line:
    if (@{*$self-&gt;{AR}} and (*$self-&gt;{AR}[-1] !~ /\n\Z/)) {
	*$self-&gt;{AR}[-1] .= shift @lines;
    }
    push @{*$self-&gt;{AR}}, @lines;       ### add the remainder
    ### print STDERR &quot;\n[[ARRAY IS NOW...\n&quot;, @{*$self-&gt;{AR}}, &quot;&lt;&lt;EOF&gt;&gt;\n&quot;;
    1;
}

#------------------------------
1;

__END__


=head1 VERSION

$Id: Lines.pm,v 1.3 2005/02/10 21:21:53 dfs Exp $


=head1 AUTHOR

Eryq (F&lt;eryq@zeegee.com&gt;).
President, ZeeGee Software Inc (F&lt;http://www.zeegee.com&gt;).

=head1 CONTRIBUTORS

Dianne Skoll (F&lt;dfs@roaringpenguin.com&gt;).

=head1 COPYRIGHT &amp; LICENSE

Copyright (c) 1997 Erik (Eryq) Dorfman, ZeeGee Software, Inc. All rights reserved.

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.

=cut
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