1 | ###########################################################################
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2 | #
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3 | # MetadataRead - like a Java interface that defines that a subclass is
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4 | # a Plugin that extracts Metadata
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5 | #
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6 | # A component of the Greenstone digital library software
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7 | # from the New Zealand Digital Library Project at the
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8 | # University of Waikato, New Zealand.
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9 | #
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10 | # Copyright (C) 2008 New Zealand Digital Library Project
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11 | #
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12 | # This program is free software; you can redistribute it and/or modify
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13 | # it under the terms of the GNU General Public License as published by
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14 | # the Free Software Foundation; either version 2 of the License, or
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15 | # (at your option) any later version.
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16 | #
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17 | # This program is distributed in the hope that it will be useful,
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18 | # but WITHOUT ANY WARRANTY; without even the implied warranty of
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19 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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20 | # GNU General Public License for more details.
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21 | #
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22 | # You should have received a copy of the GNU General Public License
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23 | # along with this program; if not, write to the Free Software
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24 | # Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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25 | #
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26 | ###########################################################################
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27 |
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28 | package MetadataRead;
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29 |
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30 | use PrintInfo;
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31 | use strict;
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32 |
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33 | # MetadataRead is an abstract superclass that does not inherit from anything else.
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34 | # It exists solely to define the can_process_this_file_for_metadata() method in
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35 | # such a way that those MetadataPlugins that inherit from MetadataRead don't need
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36 | # to define this method and will always process the files associated with them for
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37 | # metadata and other plugins in the pipeline won't be passed these files anymore.
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38 |
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39 | # MetadataRead defines method can_process_this_file_for_metadata() with identical
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40 | # signature to BasePlugin. (MetadataRead doesn't inherit from BasePlugin, so it's
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41 | # not 'overriding' it.) Subclasses of MetadataRead that want to use this method
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42 | # definition can override their inherited BasePlugin version of the method by
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43 | # listing MetadataRead as the *first* superclass they inherit from in the ISA list.
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44 | # This is the way Perl resolves conflicting method definitions.
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45 |
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46 | my $arguments = [];
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47 |
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48 | my $options = { 'name' => "MetadataRead",
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49 | 'desc' => "{MetadataRead.desc}",
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50 | 'abstract' => "yes",
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51 | 'inherits' => "yes",
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52 | 'args' => $arguments };
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53 |
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54 |
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55 | sub new {
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56 | my ($class) = shift (@_);
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57 | my ($pluginlist,$inputargs,$hashArgOptLists,$auxiliary) = @_;
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58 | push(@$pluginlist, $class);
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59 |
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60 | push(@{$hashArgOptLists->{"ArgList"}},@{$arguments});
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61 | push(@{$hashArgOptLists->{"OptList"}},$options);
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62 |
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63 | # Like PrintInfo, MetadataRead has no superclass,
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64 | # so $self is intialised to an empty array.
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65 | my $self = {};
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66 | return bless $self, $class;
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67 |
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68 | }
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69 |
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70 | # MetadataPlugins that inherit from MetadataRead will by default
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71 | # process all the metadata in files whose extensions match.
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72 | # Override this method in a subclass to return undef if other
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73 | # files should also be allowed to process the metadata therafter.
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74 | sub can_process_this_file_for_metadata {
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75 | my $self = shift(@_);
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76 |
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77 | # print STDERR "********* MetadataRead::can_process_this_file_for_metadata() called.\n";
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78 |
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79 | return $self->can_process_this_file(@_);
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80 | }
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81 |
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82 |
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83 | 1;
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