root/main/trunk/greenstone2/perllib/plugins/ReadTextFile.pm @ 23484

Revision 23484, 19.5 KB (checked in by ak19, 9 years ago)

Further improvements by Dr Bainbridge to pretty-printing.

  • Property svn:executable set to *
Line 
1###########################################################################
2#
3# ReadTxtFile.pm -- base class for import plugins that have plain text files
4# A component of the Greenstone digital library software
5# from the New Zealand Digital Library Project at the
6# University of Waikato, New Zealand.
7#
8# Copyright (C) 1999-2005 New Zealand Digital Library Project
9#
10# This program is free software; you can redistribute it and/or modify
11# it under the terms of the GNU General Public License as published by
12# the Free Software Foundation; either version 2 of the License, or
13# (at your option) any later version.
14#
15# This program is distributed in the hope that it will be useful,
16# but WITHOUT ANY WARRANTY; without even the implied warranty of
17# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18# GNU General Public License for more details.
19#
20# You should have received a copy of the GNU General Public License
21# along with this program; if not, write to the Free Software
22# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23#
24###########################################################################
25
26package ReadTextFile;
27
28use strict;
29no strict 'subs';
30no strict 'refs'; # allow filehandles to be variables and viceversa
31
32use Encode;
33
34use multiread;
35use encodings;
36use unicode;
37use textcat;
38use doc;
39use ghtml;
40use gsprintf 'gsprintf';
41
42use AutoExtractMetadata;
43
44sub BEGIN {
45    @ReadTextFile::ISA = ( 'AutoExtractMetadata' );
46}
47
48my $encoding_plus_auto_list =
49    [ { 'name' => "auto",
50    'desc' => "{ReadTextFile.input_encoding.auto}" } ];
51push(@{$encoding_plus_auto_list},@{$BasePlugin::encoding_list});
52
53my $arguments =
54    [ { 'name' => "input_encoding",
55    'desc' => "{ReadTextFile.input_encoding}",
56    'type' => "enum",
57    'list' => $encoding_plus_auto_list,
58    'reqd' => "no" ,
59    'deft' => "auto" } ,
60      { 'name' => "default_encoding",
61    'desc' => "{ReadTextFile.default_encoding}",
62    'type' => "enum",
63    'list' => $BasePlugin::encoding_list,
64    'reqd' => "no",
65        'deft' => "utf8" },
66      { 'name' => "extract_language",
67    'desc' => "{ReadTextFile.extract_language}",
68    'type' => "flag",
69    'reqd' => "no" },
70      { 'name' => "default_language",
71    'desc' => "{ReadTextFile.default_language}",
72    'type' => "string",
73    'deft' => "en",
74    'reqd' => "no" }
75      ];
76
77
78my $options = { 'name'     => "ReadTextFile",
79        'desc'     => "{ReadTextFile.desc}",
80        'abstract' => "yes",
81        'inherits' => "no",
82        'args'     => $arguments };
83
84
85
86sub new {
87    my $class = shift (@_);
88    my ($pluginlist,$inputargs,$hashArgOptLists, $auxiliary) = @_;
89    push(@$pluginlist, $class);
90
91    push(@{$hashArgOptLists->{"ArgList"}},@{$arguments});
92    push(@{$hashArgOptLists->{"OptList"}},$options);
93
94    my $self = new AutoExtractMetadata($pluginlist, $inputargs, $hashArgOptLists, $auxiliary);
95
96    return bless $self, $class;
97   
98}
99
100
101
102# The ReadTextFile read_into_doc_obj() function. This function does all the
103# right things to make general options work for a given plugin.  It reads in
104# a file and sets up a slew of metadata all saved in doc_obj, which
105# it then returns as part of a tuple (process_status,doc_obj)
106#
107# Much of this functionality used to reside in read, but it was broken
108# down into a supporting routine to make the code more flexible. 
109#
110# recursive plugins (e.g. RecPlug) and specialized plugins like those
111# capable of processing many documents within a single file (e.g.
112# GMLPlug) will normally want to implement their own version of
113# read_into_doc_obj()
114#
115# Note that $base_dir might be "" and that $file might
116# include directories
117sub read_into_doc_obj {
118    my $self = shift (@_); 
119    my ($pluginfo, $base_dir, $file, $block_hash, $metadata, $processor, $maxdocs, $total_count, $gli) = @_;
120
121    my $outhandle = $self->{'outhandle'};
122    # should we move this to read? What about secondary plugins?
123    print STDERR "<Processing n='$file' p='$self->{'plugin_type'}'>\n" if ($gli);
124    my $pp_file = &util::prettyprint_file($base_dir,$file,$gli);
125    print $outhandle "$self->{'plugin_type'} processing $pp_file\n"
126        if $self->{'verbosity'} > 1;
127
128    my ($filename_full_path, $filename_no_path) =  &util::get_full_filenames($base_dir, $file);
129
130    # Do encoding stuff
131    my ($language, $content_encoding) = $self->textcat_get_language_encoding ($filename_full_path);
132    if ($self->{'verbosity'} > 2) {
133    print $outhandle "ReadTextFile: reading $file as ($content_encoding,$language)\n";
134    }
135
136    # create a new document
137    my $doc_obj = new doc ($filename_full_path, "indexed_doc", $self->{'file_rename_method'});
138    my $top_section = $doc_obj->get_top_section();
139
140    # this should look at the plugin option too...
141    $doc_obj->add_utf8_metadata($top_section, "Plugin", "$self->{'plugin_type'}");
142    $doc_obj->add_utf8_metadata($top_section, "FileSize", (-s $filename_full_path));
143
144    my $plugin_filename_encoding = $self->{'filename_encoding'};
145    my $filename_encoding = $self->deduce_filename_encoding($file,$metadata,$plugin_filename_encoding);
146    $self->set_Source_metadata($doc_obj, $filename_full_path, $filename_encoding);
147
148    $doc_obj->add_utf8_metadata($top_section, "Language", $language);
149    $doc_obj->add_utf8_metadata($top_section, "Encoding", $content_encoding);
150   
151    # read in file ($text will be in utf8)
152    my $text = "";
153    $self->read_file ($filename_full_path, $content_encoding, $language, \$text);
154
155    if (!length ($text)) {
156    if ($gli) {
157        print STDERR "<ProcessingError n='$file' r='File contains no text'>\n";
158    }
159    gsprintf($outhandle, "$self->{'plugin_type'}: {ReadTextFile.file_has_no_text}\n", $filename_full_path) if $self->{'verbosity'};
160
161    my $failhandle = $self->{'failhandle'};
162    gsprintf($failhandle, "$file: " . ref($self) . ": {ReadTextFile.empty_file}\n");
163    # print $failhandle "$file: " . ref($self) . ": file contains no text\n";
164    $self->{'num_not_processed'} ++;
165
166    return (0,undef); # what should we return here?? error but don't want to pass it on
167    }
168   
169    # do plugin specific processing of doc_obj
170    unless (defined ($self->process (\$text, $pluginfo, $base_dir, $file, $metadata, $doc_obj, $gli))) {
171    $text = '';
172    undef $text;
173    print STDERR "<ProcessingError n='$file'>\n" if ($gli);
174    return (-1,undef);
175    }
176    $text='';
177    undef $text;
178   
179    # include any metadata passed in from previous plugins
180    # note that this metadata is associated with the top level section
181    $self->add_associated_files($doc_obj, $filename_full_path);
182    $self->extra_metadata ($doc_obj, $top_section, $metadata);
183
184     # do any automatic metadata extraction
185    $self->auto_extract_metadata ($doc_obj);
186
187
188    # if we haven't found any Title so far, assign one
189    $self->title_fallback($doc_obj,$top_section,$filename_no_path);
190
191    $self->add_OID($doc_obj);
192   
193    return (1,$doc_obj);
194}
195
196# uses the multiread package to read in the entire file pointed to
197# by filename and loads the resulting text into $$textref. Input text
198# may be in any of the encodings handled by multiread, output text
199# will be in utf8
200sub read_file {
201    my $self = shift (@_);
202    my ($filename, $encoding, $language, $textref) = @_;
203
204    if (!-r $filename)
205    {
206    my $outhandle = $self->{'outhandle'};
207    gsprintf($outhandle, "{ReadTextFile.read_denied}\n", $filename) if $self->{'verbosity'};
208    # print $outhandle "Read permission denied for $filename\n" if $self->{'verbosity'};
209    return;
210    }
211    $$textref = "";
212    if (!open (FILE, $filename)) {
213    gsprintf(STDERR, "ReadTextFile::read_file {ReadTextFile.could_not_open_for_reading} ($!)\n", $filename);
214    die "\n";
215    }
216     
217    if ($encoding eq "ascii") {
218    undef $/;
219    $$textref = <FILE>;
220    $/ = "\n";
221    } else {
222    my $reader = new multiread();
223    $reader->set_handle ('ReadTextFile::FILE');
224    $reader->set_encoding ($encoding);
225    $reader->read_file ($textref);
226    }
227
228    # At this point $$textref is a binary byte string
229    # => turn it into a Unicode aware string, so full
230    # Unicode aware pattern matching can be used.
231    # For instance: 's/\x{0101}//g' or '[[:upper:]]'
232    #
233
234    $$textref = decode("utf8",$$textref);
235
236    close FILE;
237}
238
239
240# Not currently used
241sub UNUSED_read_file_usingPerlsEncodeModule {
242##sub read_file {
243    my $self = shift (@_);
244    my ($filename, $encoding, $language, $textref) = @_;
245
246    if (!-r $filename)
247    {
248        my $outhandle = $self->{'outhandle'};
249        gsprintf($outhandle, "{ReadTextFile.read_denied}\n", $filename) if $self->{'verbosity'};
250        # print $outhandle "Read permission denied for $filename\n" if $self->{'verbosity'};
251        return;
252    }
253    $$textref = "";
254    if (!open (FILE, $filename)) {
255        gsprintf(STDERR, "ReadTextFile::read_file {ReadTextFile.could_not_open_f
256or_reading} ($!)\n", $filename);
257        die "\n";
258    }
259
260    my $store_slash = $/;
261    undef $/;
262    my $text = <FILE>;
263    $/ = $store_slash;
264
265    $$textref = decode($encoding,$text);
266
267    close FILE;
268}
269
270
271sub read_file_no_decoding {
272    my $self = shift (@_);
273    my ($filename, $textref) = @_;
274
275    if (!-r $filename)
276    {
277    my $outhandle = $self->{'outhandle'};
278    gsprintf($outhandle, "{ReadTextFile.read_denied}\n", $filename) if $self->{'verbosity'};
279    # print $outhandle "Read permission denied for $filename\n" if $self->{'verbosity'};
280    return;
281    }
282    $$textref = "";
283    if (!open (FILE, $filename)) {
284    gsprintf(STDERR, "ReadTextFile::read_file {ReadTextFile.could_not_open_for_reading} ($!)\n", $filename);
285    die "\n";
286    }
287     
288    my $reader = new multiread();
289    $reader->set_handle ('ReadTextFile::FILE');
290    $reader->read_file_no_decoding ($textref);
291   
292    $self->{'reader'} = $reader;
293
294    close FILE;
295}
296
297
298sub decode_text {
299    my $self = shift (@_);
300    my ($raw_text, $encoding, $language, $textref) = @_;
301
302    my $reader = $self->{'reader'};
303    if (!defined $reader) {
304    gsprintf(STDERR, "ReadTextFile::decode_text needs to call ReadTextFile::read_file_no_decoding first\n");
305    }
306    else {
307    $reader->set_encoding($encoding);
308    $reader->decode_text($raw_text,$textref);
309
310    # At this point $$textref is a binary byte string
311    # => turn it into a Unicode aware string, so full
312    # Unicode aware pattern matching can be used.
313    # For instance: 's/\x{0101}//g' or '[[:upper:]]'   
314   
315    $$textref = decode("utf8",$$textref);
316    }
317}
318
319
320sub textcat_get_language_encoding {
321    my $self = shift (@_);
322    my ($filename) = @_;
323
324    my ($language, $encoding, $extracted_encoding);
325    if ($self->{'input_encoding'} eq "auto") {
326        # use textcat to automatically work out the input encoding and language
327        ($language, $encoding) = $self->get_language_encoding ($filename);
328    } elsif ($self->{'extract_language'}) {
329    # use textcat to get language metadata
330        ($language, $extracted_encoding) = $self->get_language_encoding ($filename);
331        $encoding = $self->{'input_encoding'};
332    # don't print this message for english... english in utf8 is identical
333    # to english in iso-8859-1 (except for some punctuation). We don't have
334    # a language model for en_utf8, so textcat always says iso-8859-1!
335        if ($extracted_encoding ne $encoding && $language ne "en" && $self->{'verbosity'}) {
336        my $plugin_name = ref ($self);
337        my $outhandle = $self->{'outhandle'};
338        gsprintf($outhandle, "$plugin_name: {ReadTextFile.wrong_encoding}\n", $filename, $encoding, $extracted_encoding);
339        }
340    } else {
341        $language = $self->{'default_language'};
342        $encoding = $self->{'input_encoding'};
343    }
344   
345#    print STDERR "**** language encoding of contents of file $filename:\n\t****$language $encoding\n";
346
347    return ($language, $encoding);
348}
349
350
351# Uses textcat to work out the encoding and language of the text in
352# $filename. All html tags are removed before processing.
353# returns an array containing "language" and "encoding"
354sub get_language_encoding {
355    my $self = shift (@_);
356    my ($filename) = @_;
357    my $outhandle = $self->{'outhandle'};
358    my $unicode_format = "";
359    my $best_language = "";
360    my $best_encoding = "";
361   
362
363    # read in file
364    if (!open (FILE, $filename)) {
365    gsprintf(STDERR, "ReadTextFile::get_language_encoding {ReadTextFile.could_not_open_for_reading} ($!)\n", $filename);
366    # this is a pretty bad error, but try to continue anyway
367    return ($self->{'default_language'}, $self->{'input_encoding'});
368    }
369    undef $/;
370    my $text = <FILE>;
371    $/ = "\n";
372    close FILE;
373
374    # check if first few bytes have a Byte Order Marker
375    my $bom=substr($text,0,2); # check 16bit unicode
376    if ($bom eq "\xff\xfe") { # little endian 16bit unicode
377    $unicode_format="unicode";
378    } elsif ($bom eq "\xfe\xff") { # big endian 16bit unicode
379    $unicode_format="unicode";
380    } else {
381    $bom=substr($text,0,3); # check utf-8
382    if ($bom eq "\xef\xbb\xbf") { # utf-8 coded FEFF bom
383        $unicode_format="utf8";
384#   } elsif ($bom eq "\xef\xbf\xbe") { # utf-8 coded FFFE bom. Error!?
385#       $unicode_format="utf8";
386    }
387    }
388   
389    my $found_html_encoding = 0;
390    # handle html files specially
391    # XXX this doesn't match plugins derived from HTMLPlug (except ConvertTo)
392    if (ref($self) eq 'HTMLPlugin' ||
393    (exists $self->{'converted_to'} && $self->{'converted_to'} eq 'HTML')){
394
395    # remove comments in head, including multiline ones, so that we don't match on
396    # inactive tags (those that are nested inside comments)
397    my ($head) = ($text =~ m/<head>(.*)<\/head>/si);
398    $head = "" unless defined $head; # some files are not proper HTML eg php files
399    $head =~ s/<!--.*?-->//sg;
400
401    # remove <title>stuff</title> -- as titles tend often to be in English
402    # for foreign language documents
403    $text =~ s!<title>.*?</title>!!si;
404
405    # see if this html file specifies its encoding
406    if ($text =~ /^<\?xml.*encoding="(.+?)"/) {
407        $best_encoding = $1;
408    }
409    # check the meta http-equiv charset tag
410    elsif ($head =~ m/<meta http-equiv.*content-type.*charset=(.+?)\"/si) {           
411        $best_encoding = $1;
412    }
413    if ($best_encoding) { # we extracted an encoding
414        $best_encoding =~ s/-+/_/g;
415        $best_encoding = lc($best_encoding); # lowercase
416        if ($best_encoding eq "utf_8") { $best_encoding = "utf8" }
417        $found_html_encoding = 1;
418        # We shouldn't be modifying this here!!
419        #$self->{'input_encoding'} = $best_encoding;
420    }
421       
422    # remove all HTML tags
423    $text =~ s/<[^>]*>//sg;
424    }
425
426    # don't need to do textcat if we know the encoding now AND don't need to extract language
427    if($found_html_encoding && !$self->{'extract_language'}) { # encoding specified in html file
428    $best_language = $self->{'default_language'};
429    }
430
431    else { # need to use textcat to get either the language, or get both language and encoding
432    $self->{'textcat'} = new textcat() if (!defined($self->{'textcat'}));
433   
434    if($found_html_encoding) { # know encoding, find language by limiting search to known encoding
435        my $results = $self->{'textcat'}->classify_contents_for_encoding(\$text, $filename, $best_encoding);
436       
437        my $language;
438        ($language) = $results->[0] =~ m/^([^-]*)(?:-(?:.*))?$/ if (scalar @$results > 0);
439
440        if (!defined $language || scalar @$results > 3) {
441        # if there were too many results even when restricting results by encoding,
442        # or if there were no results, use default language with the known encoding
443        $best_language = $self->use_default_language($filename);
444        }
445        else { # fewer than 3 results means textcat is more certain, use the first result
446        $best_language = $language;     
447        }
448    }
449    else { # don't know encoding or language yet, therefore we use textcat
450        my $results = $self->{'textcat'}->classify_contents(\$text, $filename);
451       
452        # if textcat returns 3 or less possibilities we'll use the first one in the list
453        if (scalar @$results <= 3) { # results will be > 0 when we don't constrain textcat by an encoding
454        my ($language, $encoding) = $results->[0] =~ m/^([^-]*)(?:-(.*))?$/;
455
456        $language = $self->use_default_language($filename) unless defined $language;
457        $encoding = $self->use_default_encoding($filename) unless defined $encoding;
458
459        $best_language = $language;
460        $best_encoding = $encoding;
461        }
462        else { # if (scalar @$results > 3) {
463        if ($unicode_format) { # in case the first had a BOM
464            $best_encoding=$unicode_format;
465        }
466        else {
467            # Find the most frequent encoding in the textcat results returned
468            # Returns "" if there's no encoding more frequent than another
469            $best_encoding = $self->{'textcat'}->most_frequent_encoding($results);
470        }
471       
472        if ($best_encoding eq "") { # encoding still not set, use defaults
473            $best_language = $self->use_default_language($filename);
474            $best_encoding = $self->use_default_encoding($filename);
475        }
476        elsif (!$self->{'extract_language'}) { # know encoding but don't need to discover language
477            $best_language = $self->use_default_language($filename);
478        }
479        else { # textcat again using the most frequent encoding or the $unicode_format set above
480            $results = $self->{'textcat'}->classify_contents_for_encoding(\$text, $filename, $best_encoding);
481            my $language;
482            ($language) = $results->[0] =~ m/^([^-]*)(?:-(.*))?$/ if (scalar @$results > 0);
483            if (!defined $language || scalar @$results > 3) {
484            # if no result or too many results, use default language for the encoding previously found
485            $best_language = $self->use_default_language($filename);
486            }
487            else { # fewer than 3 results, use the language of the first result
488            $best_language = $language;
489            }
490        }
491        }
492    }
493    }
494
495    if($best_encoding eq "" || $best_language eq "") {
496    print STDERR "****Shouldn't happen: encoding and/or language still not set. Using defaults.\n";
497    $best_encoding = $self->use_default_encoding($filename) if $best_encoding eq "";
498    $best_language = $self->use_default_language($filename) if $best_language eq "";
499    }
500#    print STDERR "****Content language: $best_language; Encoding: $best_encoding.\n";
501
502
503    if ($best_encoding =~ /^iso_8859/ && &unicode::check_is_utf8($text)) {
504    # the text is valid utf8, so assume that's the real encoding
505    # (since textcat is based on probabilities)
506    $best_encoding = 'utf8';
507    }
508
509    # check for equivalents where textcat doesn't have some encodings...
510    # eg MS versions of standard encodings
511    if ($best_encoding =~ /^iso_8859_(\d+)/) {
512    my $iso = $1; # which variant of the iso standard?
513    # iso-8859 sets don't use chars 0x80-0x9f, windows codepages do
514    if ($text =~ /[\x80-\x9f]/) {
515        # Western Europe
516        if ($iso == 1 or $iso == 15) { $best_encoding = 'windows_1252' }
517        elsif ($iso == 2) {$best_encoding = 'windows_1250'} # Central Europe
518        elsif ($iso == 5) {$best_encoding = 'windows_1251'} # Cyrillic
519        elsif ($iso == 6) {$best_encoding = 'windows_1256'} # Arabic
520        elsif ($iso == 7) {$best_encoding = 'windows_1253'} # Greek
521        elsif ($iso == 8) {$best_encoding = 'windows_1255'} # Hebrew
522        elsif ($iso == 9) {$best_encoding = 'windows_1254'} # Turkish
523    }
524    }
525
526    if ($best_encoding !~ /^(ascii|utf8|unicode)$/ &&
527    !defined $encodings::encodings->{$best_encoding}) {
528    if ($self->{'verbosity'}) {
529        gsprintf($outhandle, "ReadTextFile: {ReadTextFile.unsupported_encoding}\n",
530             $filename, $best_encoding, $self->{'default_encoding'});
531    }
532    $best_encoding = $self->{'default_encoding'};
533    }
534
535    return ($best_language, $best_encoding);
536}
537
538
539sub use_default_language {
540    my $self = shift (@_);
541    my ($filename) = @_;
542
543    if ($self->{'verbosity'}>2) {
544    gsprintf($self->{'outhandle'},
545         "ReadTextFile: {ReadTextFile.could_not_extract_language}\n",
546         $filename, $self->{'default_language'});
547    }
548    return $self->{'default_language'};
549}
550
551sub use_default_encoding {
552    my $self = shift (@_);
553    my ($filename) = @_;
554
555    if ($self->{'verbosity'}>2) {
556    gsprintf($self->{'outhandle'},
557         "ReadTextFile: {ReadTextFile.could_not_extract_encoding}\n",
558         $filename, $self->{'default_encoding'});
559    }
560    return $self->{'default_encoding'};
561}
562
563# Overridden by exploding plugins (eg. ISISPlug)
564sub clean_up_after_exploding
565{
566    my $self = shift(@_);
567}
568
569
5701;
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