source: trunk/gsdl/perllib/plugins/BasPlug.pm@ 11089

###########################################################################
#
# BasPlug.pm -- base class for all the import plugins
# A component of the Greenstone digital library software
# from the New Zealand Digital Library Project at the 
# University of Waikato, New Zealand.
#
# Copyright (C) 1999-2005 New Zealand Digital Library Project
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
#
###########################################################################

package BasPlug;

BEGIN {
    die "GSDLHOME not set\n" unless defined $ENV{'GSDLHOME'};
}

eval {require bytes};

# suppress the annoying "subroutine redefined" warning that various
# plugins cause under perl 5.6
$SIG{__WARN__} = sub {warn($_[0]) unless ($_[0] =~ /Subroutine\s+\S+\sredefined/)};

use strict; 
no strict 'subs';
no strict 'refs'; # allow filehandles to be variables and viceversa

use File::Basename;

use Kea;
use multiread;
use encodings;
use cnseg;
use acronym;
use textcat;
use doc;
eval "require diagnostics"; # some perl distros (eg mac) don't have this
use DateExtract;
use ghtml;
use gsprintf 'gsprintf';
use printusage;
use parse2;


use GISBasPlug;

@BasPlug::ISA = ( GISBasPlug );

my $unicode_list =
    [ { 'name' => "ascii",
    'desc' => "{BasPlug.input_encoding.ascii}" },
      { 'name' => "utf8",
    'desc' => "{BasPlug.input_encoding.utf8}" },
      { 'name' => "unicode",
    'desc' => "{BasPlug.input_encoding.unicode}" } ];

my $auto_unicode_list = 
    [ { 'name' => "auto",
    'desc' => "{BasPlug.input_encoding.auto}" } ];

my $e = $encodings::encodings;
foreach my $enc (sort {$e->{$a}->{'name'} cmp $e->{$b}->{'name'}} keys (%$e)) 
{
    my $hashEncode =
    {'name' => $enc,
     'desc' => $e->{$enc}->{'name'}};
    
    push(@{$unicode_list},$hashEncode);
}

push(@{$auto_unicode_list},@{$unicode_list});

my $arguments =
    [ { 'name' => "process_exp",
    'desc' => "{BasPlug.process_exp}",
    'type' => "regexp",
    'deft' => "",
    'reqd' => "no" },
      { 'name' => "block_exp",
    'desc' => "{BasPlug.block_exp}",
    'type' => "regexp",
    'deft' => "",
    'reqd' => "no" },
      { 'name' => "smart_block",
    'desc' => "{BasPlug.smart_block}",
    'type' => "flag",
    'reqd' => "no",
    'hiddengli' => "yes"  },
      { 'name' => "associate_ext",
    'desc' => "{BasPlug.associate_ext}",
    'type' => "string",
    'reqd' => "no" },
      { 'name' => "input_encoding",
    'desc' => "{BasPlug.input_encoding}",
    'type' => "enum",
    'list' => $auto_unicode_list,
    'reqd' => "no" ,
    'deft' => "auto" } ,
      { 'name' => "default_encoding",
    'desc' => "{BasPlug.default_encoding}",
    'type' => "enum",
    'list' => $unicode_list,
    'reqd' => "no",
        'deft' => "utf8" },
      { 'name' => "extract_language",
    'desc' => "{BasPlug.extract_language}",
    'type' => "flag",
    'reqd' => "no" },
      { 'name' => "default_language",
    'desc' => "{BasPlug.default_language}",
    'type' => "string",
    'deft' => "en",
    'reqd' => "no" },
      { 'name' => "extract_acronyms",
    'desc' => "{BasPlug.extract_acronyms}",
    'type' => "flag",
    'reqd' => "no" },
      { 'name' => "markup_acronyms",
    'desc' => "{BasPlug.markup_acronyms}",
    'type' => "flag",
    'reqd' => "no" },
      { 'name' => "extract_keyphrases",
    'desc' => "{BasPlug.extract_keyphrases}",
    'type' => "flag",
    'reqd' => "no" },
      { 'name' => "extract_keyphrases_kea4",
    'desc' => "{BasPlug.extract_keyphrases_kea4}",
    'type' => "flag",
    'reqd' => "no" },
      { 'name' => "extract_keyphrase_options",
    'desc' => "{BasPlug.extract_keyphrase_options}",
    'type' => "string",
    'deft' => "",
    'reqd' => "no" },
      { 'name' => "first",
    'desc' => "{BasPlug.first}",
    'type' => "string",
    'reqd' => "no" },
      { 'name' => "extract_email",
    'desc' => "{BasPlug.extract_email}",
    'type' => "flag",
    'reqd' => "no" },
      { 'name' => "extract_historical_years",
    'desc' => "{BasPlug.extract_historical_years}",
    'type' => "flag",
    'reqd' => "no" },
      { 'name' => "maximum_year",
    'desc' => "{BasPlug.maximum_year}",
    'type' => "int",
    'deft' => (localtime)[5]+1900,
    'char_length' => "4",
    #'range' => "2,100",
    'reqd' => "no"},
      { 'name' => "maximum_century",
    'desc' => "{BasPlug.maximum_century}",
    'type' => "string",
    'deft' => "-1",
    'reqd' => "no" },
      { 'name' => "no_bibliography",
    'desc' => "{BasPlug.no_bibliography}",
    'type' => "flag",
    'reqd' => "no"},
      { 'name' => "no_cover_image",
    'desc' => "{BasPlug.no_cover_image}",
    'type' => "flag",
    'reqd' => "no" },
      { 'name' => "separate_cjk",
    'desc' => "{BasPlug.separate_cjk}",
    'type' => "flag",
    'reqd' => "no",
    'hiddengli' => "yes" },
      { 'name' => "new_extract_email",
    'desc' => "",
    'type' => "flag",
    'reqd' => "no",
    'hiddengli' => "yes" } ];

my $gis_arguments = 
    [ { 'name' => "extract_placenames",
    'desc' => "{GISBasPlug.extract_placenames}",
    'type' => "flag",
    'reqd' => "no" },
      { 'name' => "gazetteer",
    'desc' => "{GISBasPlug.gazetteer}",
    'type' => "string",
    'reqd' => "no" },
      { 'name' => "place_list",
    'desc' => "{GISBasPlug.place_list}",
    'type' => "flag",
    'reqd' => "no" } ];


my $options = { 'name'     => "BasPlug",
        'desc'     => "{BasPlug.desc}",
        'abstract' => "yes",
        'inherits' => "no",
        'args'     => $arguments };


sub set_keepold {
    my $self = shift(@_);
    my ($keepold) = @_;

    $self->{'keepold'} = $keepold;
}

sub get_arguments
{
    my $self = shift(@_);
    my $optionlistref = $self->{'option_list'};
    my @optionlist = @$optionlistref;
    my $pluginoptions = pop(@$optionlistref);
    my $pluginarguments = $pluginoptions->{'args'};
    return $pluginarguments;
}


sub print_xml_usage
{
    my $self = shift(@_);

    # XML output is always in UTF-8
    gsprintf::output_strings_in_UTF8;

    PrintUsage::print_xml_header();
    $self->print_xml();
}


sub print_xml
{
    my $self = shift(@_);

    my $optionlistref = $self->{'option_list'};
    my @optionlist = @$optionlistref;
    my $pluginoptions = shift(@$optionlistref);
    return if (!defined($pluginoptions));

    gsprintf(STDERR, "<PlugInfo>\n");
    gsprintf(STDERR, "  <Name>$pluginoptions->{'name'}</Name>\n");
    my $desc = gsprintf::lookup_string($pluginoptions->{'desc'});
    $desc =~ s/</&amp;lt;/g; # doubly escaped
    $desc =~ s/>/&amp;gt;/g;
    
    gsprintf(STDERR, "  <Desc>$desc</Desc>\n");
    gsprintf(STDERR, "  <Abstract>$pluginoptions->{'abstract'}</Abstract>\n");
    gsprintf(STDERR, "  <Inherits>$pluginoptions->{'inherits'}</Inherits>\n");
    gsprintf(STDERR, "  <Explodes>" . ($pluginoptions->{'explodes'} || "no") . "</Explodes>\n");
    gsprintf(STDERR, "  <Arguments>\n");
    if (defined($pluginoptions->{'args'})) {
    &PrintUsage::print_options_xml($pluginoptions->{'args'});
    }

    # Recurse up the plugin hierarchy
    $self->print_xml();

    gsprintf(STDERR, "  </Arguments>\n");
    gsprintf(STDERR, "</PlugInfo>\n");
}


sub print_txt_usage
{
    my $self = shift(@_);
    # Print the usage message for a plugin (recursively)
    my $descoffset = $self->determine_description_offset(0);
    $self->print_plugin_usage($descoffset, 1);
}


sub determine_description_offset
{
    my $self = shift(@_);
    my $maxoffset = shift(@_);

    my $optionlistref = $self->{'option_list'};
    my @optionlist = @$optionlistref;
    my $pluginoptions = shift(@$optionlistref);
    return $maxoffset if (!defined($pluginoptions));

    # Find the length of the longest option string of this plugin
    my $pluginargs = $pluginoptions->{'args'};
    if (defined($pluginargs)) {
    my $longest = &PrintUsage::find_longest_option_string($pluginargs);
    if ($longest > $maxoffset) {
        $maxoffset = $longest;
    }
    }

    # Recurse up the plugin hierarchy
    $maxoffset = $self->determine_description_offset($maxoffset);
    $self->{'option_list'} = \@optionlist;
    return $maxoffset;
}


sub print_plugin_usage
{
    my $self = shift(@_);
    my $descoffset = shift(@_);
    my $isleafclass = shift(@_);

    my $optionlistref = $self->{'option_list'};
    my @optionlist = @$optionlistref;
    my $pluginoptions = shift(@$optionlistref);
    return if (!defined($pluginoptions));

    my $pluginname = $pluginoptions->{'name'};
    my $pluginargs = $pluginoptions->{'args'};
    my $plugindesc = $pluginoptions->{'desc'};

    # Produce the usage information using the data structure above
    if ($isleafclass) {
    if (defined($plugindesc)) {
        gsprintf(STDERR, "$plugindesc\n\n");
    }
    gsprintf(STDERR, " {common.usage}: plugin $pluginname [{common.options}]\n\n");
    }

    # Display the plugin options, if there are some
    if (defined($pluginargs)) {
    # Calculate the column offset of the option descriptions
    my $optiondescoffset = $descoffset + 2;  # 2 spaces between options & descriptions

    if ($isleafclass) {
        gsprintf(STDERR, " {common.specific_options}:\n");
    }
    else {
        gsprintf(STDERR, " {common.general_options}:\n", $pluginname);
    }

    # Display the plugin options
    &PrintUsage::print_options_txt($pluginargs, $optiondescoffset);
    }

    # Recurse up the plugin hierarchy
    $self->print_plugin_usage($descoffset, 0);
    $self->{'option_list'} = \@optionlist;
}


sub new {
    # Set Encodings to the list!!


    # Start the BasPlug Constructor
    my $class = shift (@_);
    my ($pluginlist,$args,$hashArgOptLists) = @_;
    push(@$pluginlist, $class);
    my $plugin_name = (defined $pluginlist->[0]) ? $pluginlist->[0] : $class;

    if(defined $arguments){ push(@{$hashArgOptLists->{"ArgList"}},@{$arguments});}
    if(defined $options) { push(@{$hashArgOptLists->{"OptList"}},$options)};

    if (GISBasPlug::has_mapdata()) {
    push(@$arguments,@$gis_arguments);
    }
    
    my $self = {};
    $self->{'outhandle'} = STDERR;
    $self->{'option_list'} = $hashArgOptLists->{"OptList"};
    $self->{"info_only"} = 0;

    # Check if gsdlinfo is in the argument list or not - if it is, don't parse 
    # the args, just return the object.  
    foreach my $strArg (@{$args})
    {
    if($strArg eq "-gsdlinfo")
    {
        $self->{"info_only"} = 1;
        return bless $self, $class;
    }
    }

    if(!parse2::parse($args,$hashArgOptLists->{"ArgList"},$self))
    {
    my $classTempClass = bless $self, $class;
    print STDERR "<BadPlugin p=$plugin_name>\n";
    &gsprintf(STDERR, "\n{BasPlug.bad_general_option}\n", $plugin_name);
    $classTempClass->print_txt_usage("");  # Use default resource bundle
    die "\n";
    }


    delete $self->{"info_only"};
    # else parsing was successful.

    $self->{'plugin_type'} = $plugin_name;
    #$self->{'outhandle'} = STDERR;
    $self->{'textcat'} = new textcat();
    $self->{'num_processed'} = 0;
    $self->{'num_not_processed'} = 0;
    $self->{'num_blocked'} = 0;
    $self->{'num_archives'} = 0;
    $self->{'cover_image'} = 1; # cover image is on by default
    $self->{'cover_image'} = 0 if ($self->{'no_cover_image'});
    #$self->{'option_list'} = $hashArgOptLists->{"OptList"};
    
    my $associate_ext = $self->{'associate_ext'};
    if ((defined $associate_ext) && ($associate_ext ne "")) {
    my @exts = split(/,/,$associate_ext);

    my %associate_ext_lookup = ();
    foreach my $e (@exts) {
        $associate_ext_lookup{$e} = 1;
    }

    $self->{'associate_ext_lookup'} = \%associate_ext_lookup;
    }

    $self->{'shared_fileroot'} = {};
    $self->{'file_blocks'} = {};

    if ($self->{'extract_placenames'}) {

    my $outhandle = $self->{'outhandle'};
    
    my $places_ref 
        = GISBasPlug::loadGISDatabase($outhandle,$self->{'gazetteer'});
    
    if (!defined $places_ref) {
        print $outhandle "Warning: Error loading mapdata gazetteer \"$self->{'gazetteer'}\"\n";
        print $outhandle "         No placename extraction will take place.\n";
        $self->{'extract_placenames'} = undef;
    }
    else {
        $self->{'places'} = $places_ref;
    }
    }

    return bless $self, $class;
    
}

# initialize BasPlug options
# if init() is overridden in a sub-class, remember to call BasPlug::init()
sub init {
    my $self = shift (@_);
    my ($verbosity, $outhandle, $failhandle) = @_;

    # verbosity is passed through from the processor
    $self->{'verbosity'} = $verbosity;

    # as are the outhandle and failhandle
    $self->{'outhandle'} = $outhandle if defined $outhandle;
    $self->{'failhandle'} = $failhandle;

    # set process_exp and block_exp to defaults unless they were
    # explicitly set

    if ((!$self->is_recursive()) and 
    (!defined $self->{'process_exp'}) || ($self->{'process_exp'} eq "")) {

    $self->{'process_exp'} = $self->get_default_process_exp ();
    if ($self->{'process_exp'} eq "") {
        warn ref($self) . " Warning: Non-recursive plugin has no process_exp\n";
    }
    }

    if ((!defined $self->{'block_exp'}) || ($self->{'block_exp'} eq "")) {
    $self->{'block_exp'} = $self->get_default_block_exp ();
    }

}

sub begin {
    my $self = shift (@_);
    my ($pluginfo, $base_dir, $processor, $maxdocs) = @_;
    $self->initialise_extractors();
}

sub end {
    # potentially called at the end of each plugin pass 
    # import.pl only has one plugin pass, but buildcol.pl has multiple ones

    my ($self) = @_;
    $self->finalise_extractors();
}

sub deinit {
    # called only once, after all plugin passes have been done

    my ($self) = @_;
}

# this function should be overridden to return 1
# in recursive plugins
sub is_recursive {
    my $self = shift (@_);

    return 0; 
}

sub get_default_block_exp {
    my $self = shift (@_);

    return "";
}

sub get_default_process_exp {
    my $self = shift (@_);

    return "";
}

# default implementation is to do nothing. 
sub store_block_files
{
    my $self =shift (@_);
    my ($filename) = @_;
    return;
}

#default implementation is to block a file with same name as this, but extension jpg or JPG, if cover_images is on.
sub block_cover_image
{
    my $self =shift;
    my $filename = shift;

    if ($self->{'cover_image'}) {
    my $coverfile = $filename;
    $coverfile =~ s/\.[^\\\/\.]+$/\.jpg/;
    if (!-e $coverfile) {
        $coverfile =~ s/jpg$/JPG/;
    }   
    if (-e $coverfile) {
        $self->{'file_blocks'}->{$coverfile} = 1;
    } 
    }

    return;
}
    
sub metadata_read {
    my $self = shift (@_);  
    my ($pluginfo, $base_dir, $file, $metadata, $extrametakeys, $extrametadata, $processor, $maxdocs, $gli) = @_;
    # Keep track of filenames with same root but different extensions
    # Used to support -associate_ext

    my $associate_ext = $self->{'associate_ext'};
    if ((defined $associate_ext) && ($associate_ext ne "")) {

    my ($file_prefix,$file_ext) = ($file =~ m/^(.*)\.(.*?)$/);
    if ((defined $file_prefix) && (defined $file_ext)) {
        
        my $shared_fileroot = $self->{'shared_fileroot'};
        if (!defined $shared_fileroot->{$file_prefix}) {
        my $file_prefix_rec = { 'tie_to' => undef, 'exts' => {} };
        $shared_fileroot->{$file_prefix} = $file_prefix_rec;
        }
        
        my $file_prefix_rec = $shared_fileroot->{$file_prefix};

        my $process_exp = $self->{'process_exp'};

        if ($file =~ m/$self->{'process_exp'}/) {
        # This is the document the others should be tied to
        $file_prefix_rec->{'tie_to'} = $file_ext;
        }
        else {
        if (defined $self->{'associate_ext_lookup'}->{$file_ext}) {
            $file_prefix_rec->{'exts'}->{$file_ext} = 1;
        }
        }
    }
    }
    
    # now check whether we are actually processing this
    my $filename = $file;
    $filename = &util::filename_cat ($base_dir, $file) if $base_dir =~ /\w/;
    if ($self->{'process_exp'} eq "" || $filename !~ /$self->{'process_exp'}/ || !-f $filename) {
    return undef; # can't recognise
    }

    # do smart blocking if appropriate
    if ($self->{'smart_block'}) {
    $self->store_block_files($filename);
    }
    # block the cover image if there is one
    if ($self->{'cover_image'}) {
    $self->block_cover_image($filename);
    }
       
    return 1;
}

sub tie_to_filename
{
    my $self = shift (@_);  
  
    my ($file_ext,$file_prefix_rec) = @_;

    if (defined $file_prefix_rec) {
    my $tie_to = $file_prefix_rec->{'tie_to'};

    if (defined $tie_to) {
        if ($tie_to eq $file_ext) {
        return 1;
        }
    }
    }

    return 0;
}

sub tie_to_assoc_file
{
    my $self = shift (@_);    
    my ($file_ext,$file_prefix_rec) = @_;

    if (defined $file_prefix_rec) {
    my $tie_to = $file_prefix_rec->{'tie_to'};
    if (defined $tie_to) {

        my $exts = $file_prefix_rec->{'exts'};

        my $has_file_ext = $exts->{$file_ext};
        
        if ($has_file_ext) {
        return 1;
        }
    }
    }

    return 0;
}


sub associate_with
{
    my $self = shift (@_);    
    my ($file, $filename, $metadata) = @_;

    my $associate_ext = $self->{'associate_ext'};


    return 0 if (!$associate_ext);

    # If file, see if matches with "tie_to" doc or is one of the
    # associated filename extensions.

    my ($file_prefix,$file_ext) = ($file =~ m/^(.*)\.(.*?)$/);
    if ((defined $file_prefix) && (defined $file_ext)) {

    my $file_prefix_rec = $self->{'shared_fileroot'}->{$file_prefix};
    
    if ($self->tie_to_filename($file_ext,$file_prefix_rec)) {

        # Set up gsdlassocfile_tobe

        my $exts = $file_prefix_rec->{'exts'};
        
        if (!defined $metadata->{'gsdlassocfile_tobe'}) {
        $metadata->{'gsdlassocfile_tobe'} = [];
        }

        my $assoc_tobe = $metadata->{'gsdlassocfile_tobe'};
            
        my ($full_prefix) = ($filename =~ m/^(.*)\..*?$/);
        foreach my $e (keys %$exts) {       
        my $assoc_file = "$full_prefix.$e";
        my $mime_type = ""; # let system auto detect this
        push(@$assoc_tobe,"$assoc_file:$mime_type:"); 
        }
    }
    elsif ($self->tie_to_assoc_file($file_ext,$file_prefix_rec)) {
        # a form of smart block
        
        return 1;
    }
    }

    return 0;
}


sub read_block {
    my $self = shift (@_);  
  
    my ($pluginfo, $base_dir, $file, $metadata, $processor, $maxdocs, $total_count, $gli) = @_;


    my $filename = $file;
    $filename = &util::filename_cat ($base_dir, $file) if $base_dir =~ /\w/;

    if ($self->associate_with($file,$filename,$metadata)) {
    # a form of smart block
    $self->{'num_blocked'} ++;
    return (0,undef); # blocked
    }

    my $smart_block = $self->{'smart_block'};
    my $smart_block_BN = $self->{'smart_block_BN'};
   
    if ($smart_block || $smart_block_BN) {
    if (defined $self->{'file_blocks'}->{$filename} && $self->{'file_blocks'}->{$filename} == 1){
        $self->{'num_blocked'} ++;
        return (0,undef); # blocked
    }
    } else {
    if ($self->{'block_exp'} ne "" && $filename =~ /$self->{'block_exp'}/) {
        $self->{'num_blocked'} ++;
        return (0,undef); # blocked
    }
    if ($self->{'cover_image'}) {
        if (defined $self->{'file_blocks'}->{$filename} && $self->{'file_blocks'}->{$filename} == 1){
        $self->{'num_blocked'} ++;
        return (0,undef); # blocked
        }
    }
    }
    if ($filename !~ /$self->{'process_exp'}/ || !-f $filename) {
    return (undef,undef); # can't recognise
    }
    
    return (1,$filename);
}

sub read_tidy_file {

    my $self = shift (@_);  
  
    my ($file) = @_;

    $file =~ s/^[\/\\]+//; # $file often begins with / so we'll tidy it up

    return $file;
}



# The BasPlug read_into_doc_obj() function. This function does all the
# right things to make general options work for a given plugin.  It reads in
# a file and sets up a slew of metadata all saved in doc_obj, which
# it then returns as part of a tuple (process_status,doc_obj)
#
# Much of this functionality used to reside in read, but it was broken
# down into a supporting routine to make the code more flexible.  
#
# recursive plugins (e.g. RecPlug) and specialized plugins like those
# capable of processing many documents within a single file (e.g.
# GMLPlug) will normally want to implement their own version of
# read_into_doc_obj()
#
# Note that $base_dir might be "" and that $file might 
# include directories
sub read_into_doc_obj {
    my $self = shift (@_);  
    my ($pluginfo, $base_dir, $file, $metadata, $processor, $maxdocs, $total_count, $gli) = @_;

    if ($self->is_recursive()) {
    gsprintf(STDERR, "{BasPlug.read_must_be_implemented}") && die "\n";
    }

    my $outhandle   = $self->{'outhandle'};

    my ($block_status,$filename) = $self->read_block(@_);    
    return $block_status if ((!defined $block_status) || ($block_status==0));
    $file = $self->read_tidy_file($file);

    # Do encoding stuff
    my ($language, $encoding) = $self->textcat_get_language_encoding ($filename);

    # create a new document
    my $doc_obj = new doc ($filename, "indexed_doc");
    $doc_obj->set_OIDtype ($processor->{'OIDtype'});
    $doc_obj->add_utf8_metadata($doc_obj->get_top_section(), "Language", $language);
    $doc_obj->add_utf8_metadata($doc_obj->get_top_section(), "Encoding", $encoding);
    $doc_obj->add_utf8_metadata($doc_obj->get_top_section(), "Plugin", "$self->{'plugin_type'}");
    $doc_obj->add_utf8_metadata($doc_obj->get_top_section(), "FileSize", (-s $filename));

    my ($filemeta) = $file =~ /([^\\\/]+)$/;
    # how do we know what encoding the filename is in?
    $doc_obj->add_metadata($doc_obj->get_top_section(), "Source", &ghtml::dmsafe($filemeta));
    if ($self->{'cover_image'}) {
    $self->associate_cover_image($doc_obj, $filename);
    }
    
    # read in file ($text will be in utf8)
    my $text = "";
    $self->read_file ($filename, $encoding, $language, \$text);

    if (!length ($text)) {
    my $plugin_name = ref ($self);
    if ($gli) {
        print STDERR "<ProcessingError n='$file' r='File contains no text'>\n";
    }
    gsprintf($outhandle, "$plugin_name: {BasPlug.file_has_no_text}\n", $filename) if $self->{'verbosity'};

    my $failhandle = $self->{'failhandle'};
    gsprintf($failhandle, "$file: " . ref($self) . ": {BasPlug.empty_file}\n");
    # print $failhandle "$file: " . ref($self) . ": file contains no text\n";
    $self->{'num_not_processed'} ++;

    return (0,undef); # what should we return here?? error but don't want to pass it on
    }
   
    # include any metadata passed in from previous plugins 
    # note that this metadata is associated with the top level section

    $self->extra_metadata ($doc_obj, $doc_obj->get_top_section(), $metadata);

    # do plugin specific processing of doc_obj
    unless (defined ($self->process (\$text, $pluginfo, $base_dir, $file, $metadata, $doc_obj, $gli))) {
    $text = '';
    undef $text;
    print STDERR "<ProcessingError n='$file'>\n" if ($gli);
    return (-1,undef);
    }
    $text='';
    undef $text;
   
    # do any automatic metadata extraction
    $self->auto_extract_metadata ($doc_obj);
   
    # add an OID
    # see if there is a plugin-specific set_OID function...
    if (defined ($self->can('set_OID'))) {
    # it will need $doc_obj to set the Identifier metadata...
    $self->set_OID($doc_obj);
    } else {
    # use the default set_OID() in doc.pm
    $doc_obj->set_OID();
    }
    
    return (1,$doc_obj);
}


# The BasPlug read() function. This function calls read_into_doc_obj()
# to ensure all the right things to make general options work for a
# given plugin are done. It then calls the process() function which
# does all the work specific to a plugin (like the old read functions
# used to do). Most plugins should define their own process() function
# and let this read() function keep control.  
#
# recursive plugins (e.g. RecPlug) and specialized plugins like those
# capable of processing many documents within a single file (e.g.
# GMLPlug) might want to implement their own version of read(), but
# more likely need to implement their own version of read_into_doc_obj()
#
# Return number of files processed, undef if can't recognise, -1 if can't
# process

sub read {
    my $self = shift (@_);  
    my ($pluginfo, $base_dir, $file, $metadata, $processor, $maxdocs, $total_count, $gli) = @_;

    my ($process_status,$doc_obj) = $self->read_into_doc_obj(@_);
    
    if ((defined $process_status) && ($process_status == 1)) {
    # process the document
    $processor->process($doc_obj);
    
    if(defined($self->{'places_filename'})){
        &util::rm($self->{'places_filename'});
        $self->{'places_filename'} = undef;
    }
    
    $self->{'num_processed'} ++;
    undef $doc_obj; 
    }

    # if process_status == 1, then the file has been processed.
    return $process_status;

}

# returns undef if file is rejected by the plugin
sub process {
    my $self = shift (@_);
    my ($textref, $pluginfo, $base_dir, $file, $metadata, $doc_obj, $gli) = @_;

    gsprintf(STDERR, "BasPlug::process {common.must_be_implemented}\n") && die "\n";
    # die "Basplug::process function must be implemented in sub-class\n";

    return undef; # never gets here
}

# uses the multiread package to read in the entire file pointed to
# by filename and loads the resulting text into $$textref. Input text
# may be in any of the encodings handled by multiread, output text
# will be in utf8
sub read_file {
    my $self = shift (@_);
    my ($filename, $encoding, $language, $textref) = @_;

    if (!-r $filename)
    {
    my $outhandle = $self->{'outhandle'};
    gsprintf($outhandle, "{BasPlug.read_denied}\n", $filename) if $self->{'verbosity'};
    # print $outhandle "Read permission denied for $filename\n" if $self->{'verbosity'};
    return;
    }
    $$textref = "";
    if (!open (FILE, $filename)) {
    gsprintf(STDERR, "BasPlug::read_file {BasPlug.could_not_open_for_reading} ($!)\n", $filename);
    die "\n";
    }
     
    if ($encoding eq "ascii") {
    undef $/;
    $$textref = <FILE>;
    $/ = "\n";
    } else {
    my $reader = new multiread();
    $reader->set_handle ('BasPlug::FILE');
    $reader->set_encoding ($encoding);
    $reader->read_file ($textref);
        #Now segments chinese if the separate_cjk option is set
    if ($self->{'separate_cjk'}) {
        # segment the Chinese words
        $$textref = &cnseg::segment($$textref);
    }
    }
    close FILE;
}

# write_file -- used by ConvertToPlug, for example in post processing
#
sub utf8_write_file {
    my $self = shift (@_);
    my ($textref, $filename) = @_;
    
    if (!open (FILE, ">$filename")) {
    gsprintf(STDERR, "ConvertToPlug::write_file {ConvertToPlug.could_not_open_for_writing} ($!)\n", $filename);
     die "\n";
     }
    print FILE $$textref;
    
    close FILE;
}


sub filename_based_title
{
    my $self = shift (@_);
    my ($file) = @_;

    my $file_derived_title = $file;
    $file_derived_title =~ s/_/ /g;
    $file_derived_title =~ s/\..*?$//;

    return $file_derived_title;
}


sub title_fallback
{
    my $self = shift (@_);
    my ($doc_obj,$section,$file) = @_;

    if (!defined $doc_obj->get_metadata_element ($section, "Title")) {

    my $file_derived_title = $self->filename_based_title($file);
    $doc_obj->add_metadata ($section, "Title", $file_derived_title);
    }
}

sub textcat_get_language_encoding {
    my $self = shift (@_);
    my ($filename) = @_;

    
    my ($language, $encoding, $extracted_encoding);
    if ($self->{'input_encoding'} eq "auto") {
        # use textcat to automatically work out the input encoding and language
        ($language, $encoding) = $self->get_language_encoding ($filename);
    } elsif ($self->{'extract_language'}) {
        # use textcat to get language metadata
        ($language, $extracted_encoding) = $self->get_language_encoding ($filename);
        $encoding = $self->{'input_encoding'};
    # don't print this message for english... english in utf8 is identical
    # to english in iso-8859-1 (except for some punctuation). We don't have
    # a language model for en_utf8, so textcat always says iso-8859-1!
        if ($extracted_encoding ne $encoding && $language ne "en"
        && $self->{'verbosity'}) {
        my $plugin_name = ref ($self);
        my $outhandle = $self->{'outhandle'};
        gsprintf($outhandle, "$plugin_name: {BasPlug.wrong_encoding}\n", $filename, $encoding, $extracted_encoding);
            # print $outhandle "$plugin_name: WARNING: $filename was read using $encoding encoding but ";
            # print $outhandle "appears to be encoded as $extracted_encoding.\n";
        }
    } else {
        $language = $self->{'default_language'};
        $encoding = $self->{'input_encoding'};
    }

    return ($language, $encoding);
}

# Uses textcat to work out the encoding and language of the text in 
# $filename. All html tags are removed before processing.
# returns an array containing "language" and "encoding"
sub get_language_encoding {
    my $self = shift (@_);
    my ($filename) = @_;
    my $outhandle = $self->{'outhandle'};
    my $unicode_format = "";
    # read in file
    open (FILE, $filename) || (gsprintf(STDERR, "BasPlug::get_language_encoding {BasPlug.could_not_open_for_reading} ($!)\n", $filename) && die "\n"); # die "BasPlug::get_language_encoding could not open $filename for reading ($!)\n";
    undef $/;
    my $text = <FILE>;
    $/ = "\n";
    close FILE;

    # check if first few bytes have a Byte Order Marker
    my $bom=substr($text,0,2); # check 16bit unicode
    if ($bom eq "\xff\xfe") { # little endian 16bit unicode
    $unicode_format="unicode";
    } elsif ($bom eq "\xfe\xff") { # big endian 16bit unicode
    $unicode_format="unicode";
    } else {
    $bom=substr($text,0,3); # check utf-8
    if ($bom eq "\xef\xbb\xbf") { # utf-8 coded FEFF bom
        $unicode_format="utf8";
#   } elsif ($bom eq "\xef\xbf\xbe") { # utf-8 coded FFFE bom. Error!?
#       $unicode_format="utf8";
    }
    }
    
    # VB scripting generated Word to HTML file
    if ($text =~ /charset=(windows.*)[\"]/ig){
    my $vbhtml_encoding = $1;
    $vbhtml_encoding =~ s/-+/_/g;
    $self->{'input_encoding'} = $vbhtml_encoding;
    }
    
    # remove <title>stuff</title> -- as titles tend often to be in English
    # for foreign language documents
    $text =~ s/<title>(.|\n)*?<\/title>//i;

    # remove all HTML tags
    # XXX this doesn't match plugins derived from HTMLPlug (except ConvertTo)
    if (ref($self) eq 'HTMLPlug' ||
    (exists $self->{'converted_to'} && $self->{'converted_to'} eq 'HTML')){
    $text =~ s/<[^>]*>//sg;
    }

    # get the language/encoding
    my $results = $self->{'textcat'}->classify(\$text);

    # if textcat returns 3 or less possibilities we'll use the 
    # first one in the list - otherwise use the defaults
    if (scalar @$results > 3) {
    my $best_encoding="";
    if ($unicode_format) { # in case the first had a BOM
        $best_encoding=$unicode_format;
    } else {
        my %guessed_encodings = ();
        foreach my $result (@$results) {
        $result =~ /([^\-]+)$/;
        my $enc=$1;
        if (!defined($guessed_encodings{$enc})) {
            $guessed_encodings{$enc}=0;
        }
        $guessed_encodings{$enc}++;
        }

        $guessed_encodings{""}=-1; # for default best_encoding of ""
        foreach my $enc (keys %guessed_encodings) {
        if ($guessed_encodings{$enc} >
            $guessed_encodings{$best_encoding}){
            $best_encoding=$enc;
        }
        }
    }

    if ($self->{'input_encoding'} ne 'auto') {
        if ($self->{'extract_language'} && ($self->{'verbosity'}>2)) {
        gsprintf($outhandle,
             "BasPlug: {BasPlug.could_not_extract_language}\n",
             $filename, $self->{'default_language'});
        }       
        return ($self->{'default_language'}, $self->{'input_encoding'});

    } else {
        if ($self->{'verbosity'}>2) {
        gsprintf($outhandle,
             "BasPlug: {BasPlug.could_not_extract_language}\n",
             $filename, $self->{'default_language'});
        }
        return ($self->{'default_language'}, $best_encoding);
    }
    }

    # format language/encoding
    my ($language, $encoding) = $results->[0] =~ /^([^-]*)(?:-(.*))?$/;
    if (!defined $language) {
    if ($self->{'verbosity'}>2) {
        gsprintf($outhandle,
             "BasPlug: {BasPlug.could_not_extract_language}\n",
             $filename, $self->{'default_language'});
    }
    $language = $self->{'default_language'};
    }
    if (!defined $encoding) {
    if ($self->{'verbosity'}>2) {
        gsprintf($outhandle,
             "BasPlug: {BasPlug.could_not_extract_encoding}\n",
             $filename, $self->{'default_encoding'});
    }
    $encoding = $self->{'default_encoding'};
    }


    # check for equivalents where textcat doesn't have some encodings...
    # eg MS versions of standard encodings
    if ($encoding =~ /^iso_8859_(\d+)/) {
    my $iso = $1; # which variant of the iso standard?
    # iso-8859 sets don't use chars 0x80-0x9f, windows codepages do
    if ($text =~ /[\x80-\x9f]/) {
        # Western Europe
        if ($iso == 1 or $iso == 15) { $encoding = 'windows_1252' }
        elsif ($iso == 2) { $encoding = 'windows_1250' } # Central Europe
        elsif ($iso == 5) { $encoding = 'windows_1251' } # Cyrillic
        elsif ($iso == 6) { $encoding = 'windows_1256' } # Arabic
        elsif ($iso == 7) { $encoding = 'windows_1253' } # Greek
        elsif ($iso == 8) { $encoding = 'windows_1255' } # Hebrew
        elsif ($iso == 9) { $encoding = 'windows_1254' } # Turkish
    }
    }

    if ($encoding !~ /^(ascii|utf8|unicode)$/ &&
    !defined $encodings::encodings->{$encoding}) {
    if ($self->{'verbosity'}) {
        gsprintf($outhandle, "BasPlug: {BasPlug.unsupported_encoding}\n",
             $filename, $encoding, $self->{'default_encoding'});
    }
    $encoding = $self->{'default_encoding'};
    }

    return ($language, $encoding);
}

# add any extra metadata that's been passed around from one
# plugin to another.
# extra_metadata uses add_utf8_metadata so it expects metadata values
# to already be in utf8
sub extra_metadata {
    my $self = shift (@_);
    my ($doc_obj, $cursection, $metadata) = @_;

    foreach my $field (keys(%$metadata)) {
    # $metadata->{$field} may be an array reference
    if ($field eq "gsdlassocfile_tobe") {
        # 'gsdlassocfile_tobe' is artificially introduced metadata
        # that is used to signal that certain additional files should
        # be tied to this document.  Useful in situations where a
        # metadata pass in the plugin pipeline works out some files
        # need to be associated with a document, but the document hasn't
        # been formed yet.
        
        my $equiv_form = "";
        foreach my $gaf (@{$metadata->{$field}}) {
        my ($full_filename,$mimetype) = ($gaf =~ m/^(.*):(.*):$/);
        my ($tail_filename) = ($full_filename =~ /^.*[\/\\](.+?)$/);
        my $filename = $full_filename;
                  
        $doc_obj->associate_file($full_filename,$tail_filename,$mimetype);
        
        my ($doc_ext) = ($tail_filename =~ m/^.*\.(.*)$/);
        my $start_doclink = "<a href=\"_httpcollection_/index/assoc/{Or}{[parent(Top):archivedir],[archivedir]}/$tail_filename\">";
        my $srcicon = "_icon".$doc_ext."_";
        my $end_doclink = "</a>";

        $equiv_form .= " $start_doclink\{If\}{$srcicon,$srcicon,$doc_ext\}$end_doclink";        
        }
        $doc_obj->add_utf8_metadata ($cursection, "equivlink", $equiv_form); 
    }
    elsif (ref ($metadata->{$field}) eq "ARRAY") {
        map { 
        $doc_obj->add_utf8_metadata ($cursection, $field, $_); 
        } @{$metadata->{$field}};
    } else {
        $doc_obj->add_utf8_metadata ($cursection, $field, $metadata->{$field}); 
    }
    }
}

# initialise metadata extractors
sub initialise_extractors {
    my $self = shift (@_);

    if ($self->{'extract_acronyms'} || $self->{'markup_acronyms'}) {
    &acronym::initialise_acronyms();
    }
}

# finalise metadata extractors
sub finalise_extractors {
    my $self = shift (@_);

    if ($self->{'extract_acronyms'} || $self->{'markup_acronyms'}) {
    &acronym::finalise_acronyms();
    }
}

# FIRSTNNN: extract the first NNN characters as metadata
sub extract_first_NNNN_characters {
    my $self = shift (@_);
    my ($textref, $doc_obj, $thissection) = @_;
    
    foreach my $size (split /,/, $self->{'first'}) {
    my $tmptext =  $$textref;
    $tmptext =~ s/^\s+//;
    $tmptext =~ s/\s+$//;
    $tmptext =~ s/\s+/ /gs;
    $tmptext = substr ($tmptext, 0, $size);
    $tmptext =~ s/\s\S*$/&#8230;/;
    $doc_obj->add_utf8_metadata ($thissection, "First$size", $tmptext);
    }
}

sub extract_email {
    my $self = shift (@_);
    my ($textref, $doc_obj, $thissection) = @_;
    my $outhandle = $self->{'outhandle'};

    gsprintf($outhandle, " {BasPlug.extracting_emails}...\n")
    if ($self->{'verbosity'} > 2);
    
    my @email = ($$textref =~ m/([-a-z0-9\.@+_=]+@(?:[-a-z0-9]+\.)+(?:com|org|edu|mil|int|net|[a-z][a-z]))/g);
    @email = sort @email;
    
#    if($self->{"new_extract_email"} == 0)
#    {
#    my @email2 = ();
#    foreach my $address (@email) 
#   {
#   if (!(join(" ",@email2) =~ m/(^| )$address( |$)/ )) 
#       {
#       push @email2, $address;
#       $doc_obj->add_utf8_metadata ($thissection, "emailAddress", $address);
#       # print $outhandle "  extracting $address\n" 
#       &gsprintf($outhandle, "  {BasPlug.extracting} $address\n")
#           if ($self->{'verbosity'} > 3);
#       }
#   }
#    }
#    else
#    {
    my $hashExistMail = {};
    foreach my $address (@email) {
    if (!(defined $hashExistMail->{$address}))
    {
        $hashExistMail->{$address} = 1;
        $doc_obj->add_utf8_metadata ($thissection, "emailAddress", $address);
        gsprintf($outhandle, "  {BasPlug.extracting} $address\n")
        if ($self->{'verbosity'} > 3);
    }
    }
    gsprintf($outhandle, " {BasPlug.done_email_extract}\n")
    if ($self->{'verbosity'} > 2);
}

# extract metadata
sub auto_extract_metadata {

    my $self = shift (@_);
    my ($doc_obj) = @_;
    
    if ($self->{'extract_email'}) {
    my $thissection = $doc_obj->get_top_section();
    while (defined $thissection) {
        my $text = $doc_obj->get_text($thissection);
        $self->extract_email (\$text, $doc_obj, $thissection) if $text =~ /./;
        $thissection = $doc_obj->get_next_section ($thissection);
    }
    } 
    if ($self->{'extract_placenames'}) {
    my $thissection = $doc_obj->get_top_section();
    while (defined $thissection) {
        my $text = $doc_obj->get_text($thissection);
        $self->extract_placenames (\$text, $doc_obj, $thissection) if $text =~ /./;
        $thissection = $doc_obj->get_next_section ($thissection);
    }
    } 

    if ($self->{'extract_keyphrases'} || $self->{'extract_keyphrases_kea4'}) {
    $self->extract_keyphrases($doc_obj);
    }

    if ($self->{'first'}) {
    my $thissection = $doc_obj->get_top_section();
    while (defined $thissection) {
        my $text = $doc_obj->get_text($thissection);
        $self->extract_first_NNNN_characters (\$text, $doc_obj, $thissection) if $text =~ /./;
        $thissection = $doc_obj->get_next_section ($thissection);
    }
    }   
    
    if ($self->{'extract_acronyms'}) {
    my $thissection = $doc_obj->get_top_section();
    while (defined $thissection) {
        my $text = $doc_obj->get_text($thissection);
        $self->extract_acronyms (\$text, $doc_obj, $thissection) if $text =~ /./;
        $thissection = $doc_obj->get_next_section ($thissection);
    }
    }
    
    if ($self->{'markup_acronyms'}) {
    my $thissection = $doc_obj->get_top_section();
    while (defined $thissection) {
        my $text = $doc_obj->get_text($thissection);
        $text = $self->markup_acronyms ($text, $doc_obj, $thissection);
        $doc_obj->delete_text($thissection);
        $doc_obj->add_text($thissection, $text);
        $thissection = $doc_obj->get_next_section ($thissection);
    }
    }

    if($self->{'extract_historical_years'}) {
    my $thissection = $doc_obj->get_top_section();
    while (defined $thissection) {

        my $text = $doc_obj->get_text($thissection);
        &DateExtract::get_date_metadata($text, $doc_obj, 
                        $thissection, 
                        $self->{'no_bibliography'}, 
                        $self->{'maximum_year'}, 
                        $self->{'maximum_century'});
        $thissection = $doc_obj->get_next_section ($thissection);
    }
    }
}


#adding kea keyphrases
sub extract_keyphrases
{
    my $self = shift(@_);
    my $doc_obj = shift(@_);

    # Use Kea 3.0 unless 4.0 has been specified
    my $kea_version = "3.0";
    if ($self->{'extract_keyphrases_kea4'}) {
    $kea_version = "4.0";
    }

    # Check that Kea exists, and tell the user where to get it if not
    my $keahome = &Kea::get_Kea_directory($kea_version);
    if (!-e $keahome) {
    gsprintf(STDERR, "{BasPlug.missing_kea}\n", $keahome, $kea_version);
    return;
    }

    my $thissection = $doc_obj->get_top_section();
    my $text = "";
    my $list;

    #loop through sections to gather whole doc
    while (defined $thissection) { 
    my $sectiontext = $doc_obj->get_text($thissection);   
    $text = $text.$sectiontext;
    $thissection = $doc_obj->get_next_section ($thissection);
    } 
   
    if($self->{'extract_keyphrase_options'}) { #if kea options flag is set, call Kea with specified options 
    $list = &Kea::extract_KeyPhrases ($kea_version, $text, $self->{'extract_keyphrase_options'});
    } else { #otherwise call Kea with no options
    $list = &Kea::extract_KeyPhrases ($kea_version, $text);
    }
 
    if ($list){
    # if a list of kea keyphrases was returned (ie not empty)
    if ($self->{'verbosity'}) {
        gsprintf(STDERR, "{BasPlug.keyphrases}: $list\n");
    }

    #add metadata to top section
    $thissection = $doc_obj->get_top_section(); 

    # add all key phrases as one metadata
    $doc_obj->add_metadata($thissection, "Keyphrases", $list);

    # add individual key phrases as multiple metadata
    foreach my $keyphrase (split(',', $list)) {
        $keyphrase =~ s/^\s+|\s+$//g;
        $doc_obj->add_metadata($thissection, "Keyphrase", $keyphrase);
    }
    }
}


# extract acronyms from a section in a document. progress is 
# reported to outhandle based on the verbosity. both the Acronym
# and the AcronymKWIC metadata items are created. 

sub extract_acronyms {
    my $self = shift (@_);
    my ($textref, $doc_obj, $thissection) = @_;
    my $outhandle = $self->{'outhandle'};

    # print $outhandle " extracting acronyms ...\n" 
    gsprintf($outhandle, " {BasPlug.extracting_acronyms}...\n")
    if ($self->{'verbosity'} > 2);

    my $acro_array =  &acronym::acronyms($textref);
    
    foreach my $acro (@$acro_array) {

    #check that this is the first time ...
    my $seen_before = "false";
    my $previous_data = $doc_obj->get_metadata($thissection, "Acronym");
    foreach my $thisAcro (@$previous_data) {
        if ($thisAcro eq $acro->to_string()) {
        $seen_before = "true";
        if ($self->{'verbosity'} >= 4) {
            gsprintf($outhandle, " {BasPlug.already_seen} " .
                 $acro->to_string() . "\n");
        }
        }
    }

    if ($seen_before eq "false") {
        #write it to the file ...
        $acro->write_to_file();

        #do the normal acronym
        $doc_obj->add_utf8_metadata($thissection, "Acronym",  $acro->to_string());
        gsprintf($outhandle, " {BasPlug.adding} ".$acro->to_string()."\n")
        if ($self->{'verbosity'} > 3);
    }
    }

    gsprintf($outhandle, " {BasPlug.done_acronym_extract}\n")
    if ($self->{'verbosity'} > 2);
}

sub markup_acronyms {
    my $self = shift (@_);
    my ($text, $doc_obj, $thissection) = @_;
    my $outhandle = $self->{'outhandle'};

    gsprintf($outhandle, " {BasPlug.marking_up_acronyms}...\n")
    if ($self->{'verbosity'} > 2);

    #self is passed in to check for verbosity ...
    $text = &acronym::markup_acronyms($text, $self);

    gsprintf($outhandle, " {BasPlug.done_acronym_markup}\n")
    if ($self->{'verbosity'} > 2);

    return $text;
}

sub compile_stats {
    my $self = shift(@_);
    my ($stats) = @_;

    $stats->{'num_processed'} += $self->{'num_processed'};
    $stats->{'num_not_processed'} += $self->{'num_not_processed'};
    $stats->{'num_archives'} += $self->{'num_archives'};

}

sub associate_cover_image {
    my $self = shift;
    my ($doc_obj, $filename) = @_;

    $filename =~ s/\.[^\\\/\.]+$/\.jpg/;
    if (exists $self->{'covers_missing_cache'}->{$filename}) {
    # don't stat() for existence eg for multiple document input files
    # (eg SplitPlug)
    return;
    }

    my $top_section=$doc_obj->get_top_section();

    if (-e $filename) {
    $doc_obj->associate_file($filename, "cover.jpg", "image/jpeg");
    $doc_obj->add_utf8_metadata($top_section, "hascover",  1);
    } else {
    my $upper_filename = $filename;
    $upper_filename =~ s/jpg$/JPG/;
    if (-e $upper_filename) {
        $doc_obj->associate_file($upper_filename, "cover.jpg",
                     "image/jpeg");
        $doc_obj->add_utf8_metadata($top_section, "hascover",  1);
    } else {
        # file doesn't exist, so record the fact that it's missing so
        # we don't stat() again (stat is slow)
        $self->{'covers_missing_cache'}->{$filename} = 1;
    }
    }

}

1;