#!/usr/bin/perl -w
###############################################################################
=pod

=head1 NAME

join_lines_if_short - program for joining some adjacent lines from stdin or one
or more files

=head1 SYNOPSIS

B<join_lines_if_short> [options...] [text files...]

=head1 DESCRIPTION

B<join_lines_if_short> is used to join adjacent lines from stdin or one or more
files, trimming trailing line feeds and carriage returns, and sending the output
to stdout.  Lines are only joined if the first line is short the expected number
of columns.

=head1 OVERVIEW

B<join_lines_if_short> understands the following optional arguments:

=over 15

=item --help

Show this documentation.

=item --delimiter=<d>

B<join_lines_if_short> will use the specified delimiter <d> for determining the
column count for each line.  The default is to assume tab as the delimiter.

=item --join_delimiter=<d>

B<join_lines_if_short> will use the specified delimiter <d> when joining lines.
The default is to use no delimiter.

=item --columns=<n>

B<join_lines_if_short> will expect each line to contain <n> columns.  If a line
has fewer than <n> columns, then this is the trigger for joining that line with
the next line.  The new line will be reconsidered and potentially joined with
the next line and so on.

=back

=cut
###############################################################################

use strict;
use Pod::Usage;
use Getopt::Long;

my $help;
my $delimiter = "\t";
my $join_delimiter = "";
my $colcount;

GetOptions(
	'delimiter=s' => \$delimiter,
	'join_delimiter=s' => \$join_delimiter,
	'columns=s' => \$colcount,
	'help|?' => \$help
);
pod2usage(-verbose => 2) if $help || ! defined $colcount; 

my $line_buffer = '';
while (my $line = <>) {
    chomp $line;
    if ($line_buffer eq '') {
        $line_buffer = $line;
    } else {
        $line_buffer = "$line_buffer$join_delimiter$line";
    }
    my @f = split /$delimiter/, $line_buffer, -1;
    if (scalar(@f) >= $colcount) {
        $line_buffer =~ s/\x0D//g; # strip embedded carriage returns
        print "$line_buffer\n";
        $line_buffer = '';
    }
}
if ($line_buffer ne '') {
    print "$line_buffer\n";
}