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package Vnlog::Parser;
use strict;
use warnings;
use feature ':5.10';
our $VERSION = 1.00;
use base 'Exporter';
our @EXPORT_OK = qw();
sub new
{
my $classname = shift;
my $this = { 'keys' => undef,
'values' => undef,
'error' => '',
'values_hash' => undef};
bless($this, $classname);
return $this;
}
sub parse
{
my ($this, $line) = @_;
# I reset the data first
$this->{values} = undef;
$this->{values_hash} = undef;
if( $line =~ /^\s*(?:#[#!]|#\s*$|$)/p)
{
# empty line or hard comment.
# no data, no error
return 1;
}
if( $line =~ /^\s*#\s*(.*?)\s*$/ )
{
if( $this->{keys} )
{
# already have legend, so this is just a comment
# no data, no error
return 1;
}
# got legend.
# no data, no error
$this->{keys} = [ split(' ', $1) ];
return 1;
}
if( !$this->{'keys'} )
{
# Not comment, not empty line, but no legend yet. Barf
$this->{error} = "Got dataline before legend";
return undef;
}
$line =~ /^\s*(.*?)\s*$/; # get the non-newline part. Like chomp, but
# non-destructive
$this->{values} = [ map {$_ eq '-' ? undef : $_} split(' ', $1) ];
if( scalar @{$this->{'keys'}} != scalar @{$this->{'values'}} )
{
# mismatched key/value counts
$this->{error} = sprintf('Legend line "%s" has %d elements, but data line "%s" has %d elements. Counts must match!',
"# " . join(' ', @{$this->{'keys'}}),
scalar @{$this->{'keys'}},
$line,
scalar @{$this->{'values'}});
return undef;
}
return 1;
}
sub error
{
my ($this) = @_;
return $this->{error};
}
sub getKeys
{
my ($this) = @_;
return $this->{keys};
}
sub getValues
{
my ($this) = @_;
return $this->{values}
}
sub getValuesHash
{
my ($this) = @_;
# internally:
# $this->{values_hash} == undef: not yet computed
# $this->{values_hash} == {}: computed, but no-data
# returning: undef if computed, but no-data
if( defined $this->{values_hash} )
{
return undef if 0 == scalar(%{$this->{values_hash}});
return $this->{values_hash};
}
$this->{values_hash} = {};
if($this->{keys} && $this->{values})
{
for my $i (0..$#{$this->{keys}})
{
$this->{values_hash}{$this->{keys}[$i]} = $this->{values}[$i];
}
}
return $this->{values_hash};
}
1;
=head1 NAME
Vnlog::Parser - Simple library to parse vnlog data
=head1 SYNOPSIS
use Vnlog::Parser;
my $parser = Vnlog::Parser->new();
while (<DATA>)
{
if( !$parser->parse($_) )
{
die "Error parsing vnlog line '$_': " . $parser->error();
}
my $d = $parser->getValuesHash();
next unless %$d;
say "$d->{time}: $d->{height}";
}
=head1 DESCRIPTION
This is a simple perl script to parse vnlog input and make the incoming
key/values available. The example above is representative of normal use. API
functions are
=over
=item *
new()
Creates new Vnlog::Parser object. Takes no arguments.
=item *
parse(line)
Method to call for each input line. On error, a false value is returned.
=item *
error()
If an error occurred, returns a string that describes the error.
=item *
getKeys()
Returns a list-ref containing the current column labels or undef if this hasn't
been parsed yet.
=item *
getValues()
Returns a list-ref containing the values for the current line or undef if there
aren't any. This isn't an error necessarily because this line could have been a
comment. Empty fields are '-' in the vnlog and undef in the values returned
here.
=item *
getValuesHash()
Returns a hash-ref containing the key-value mapping for the current line or
undef if there's no data in this line. This isn't an error necessarily because
this line could have been a comment. Empty fields are '-' in the vnlog and undef
in the values returned here.
=item *
=back
=head1 REPOSITORY
L<https://github.com/dkogan/vnlog>
=head1 AUTHOR
Dima Kogan, C<< <dima@secretsauce.net> >>
=head1 LICENSE AND COPYRIGHT
Copyright 2016 California Institute of Technology.
This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the Free
Software Foundation; either version 2.1 of the License, or (at your option) any
later version.
=cut
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