root/gs2-extensions/ngramj/perllib/plugins/ReadTextFile.pm @ 25141

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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 ngramj;
39use doc;
40use ghtml;
41use gsprintf 'gsprintf';
42
43use AutoExtractMetadata;
44
45sub BEGIN {
46    @ReadTextFile::ISA = ( 'AutoExtractMetadata' );
47}
48
49my $encoding_plus_auto_list =
50    [ { 'name' => "auto",
51    'desc' => "{ReadTextFile.input_encoding.auto}" } ];
52push(@{$encoding_plus_auto_list},@{$BasePlugin::encoding_list});
53
54my $arguments =
55    [ { 'name' => "input_encoding",
56    'desc' => "{ReadTextFile.input_encoding}",
57    'type' => "enum",
58    'list' => $encoding_plus_auto_list,
59    'reqd' => "no" ,
60    'deft' => "auto" } ,
61      { 'name' => "default_encoding",
62    'desc' => "{ReadTextFile.default_encoding}",
63    'type' => "enum",
64    'list' => $BasePlugin::encoding_list,
65    'reqd' => "no",
66        'deft' => "utf8" },
67      { 'name' => "extract_language",
68    'desc' => "{ReadTextFile.extract_language}",
69    'type' => "flag",
70    'reqd' => "no" },
71      { 'name' => "default_language",
72    'desc' => "{ReadTextFile.default_language}",
73    'type' => "string",
74    'deft' => "en",
75    'reqd' => "no" }
76      ];
77
78
79my $options = { 'name'     => "ReadTextFile",
80        'desc'     => "{ReadTextFile.desc}",
81        'abstract' => "yes",
82        'inherits' => "no",
83        'args'     => $arguments };
84
85
86
87sub new {
88    my $class = shift (@_);
89    my ($pluginlist,$inputargs,$hashArgOptLists, $auxiliary) = @_;
90    push(@$pluginlist, $class);
91
92    push(@{$hashArgOptLists->{"ArgList"}},@{$arguments});
93    push(@{$hashArgOptLists->{"OptList"}},$options);
94
95    my $self = new AutoExtractMetadata($pluginlist, $inputargs, $hashArgOptLists, $auxiliary);
96
97    return bless $self, $class;
98   
99}
100
101
102
103# The ReadTextFile read_into_doc_obj() function. This function does all the
104# right things to make general options work for a given plugin.  It reads in
105# a file and sets up a slew of metadata all saved in doc_obj, which
106# it then returns as part of a tuple (process_status,doc_obj)
107#
108# Much of this functionality used to reside in read, but it was broken
109# down into a supporting routine to make the code more flexible. 
110#
111# recursive plugins (e.g. RecPlug) and specialized plugins like those
112# capable of processing many documents within a single file (e.g.
113# GMLPlug) will normally want to implement their own version of
114# read_into_doc_obj()
115#
116# Note that $base_dir might be "" and that $file might
117# include directories
118sub read_into_doc_obj {
119    my $self = shift (@_); 
120    my ($pluginfo, $base_dir, $file, $block_hash, $metadata, $processor, $maxdocs, $total_count, $gli) = @_;
121
122    print STDERR "**** In Pei Jones Local version of ReadTextFile\n";
123   
124    my $outhandle = $self->{'outhandle'};
125    # should we move this to read? What about secondary plugins?
126    print STDERR "<Processing n='$file' p='$self->{'plugin_type'}'>\n" if ($gli);
127    my $pp_file = &util::prettyprint_file($base_dir,$file,$gli);
128    print $outhandle "$self->{'plugin_type'} processing $pp_file\n"
129        if $self->{'verbosity'} > 1;
130
131    my ($filename_full_path, $filename_no_path) =  &util::get_full_filenames($base_dir, $file);
132
133    # Do encoding stuff
134    my ($language, $content_encoding) = $self->textcat_get_language_encoding ($filename_full_path);
135    if ($self->{'verbosity'} > 2) {
136    print $outhandle "ReadTextFile: reading $file as ($content_encoding,$language)\n";
137    }
138
139    # create a new document
140    my $doc_obj = new doc ($filename_full_path, "indexed_doc", $self->{'file_rename_method'});
141    my $top_section = $doc_obj->get_top_section();
142
143    # this should look at the plugin option too...
144    $doc_obj->add_utf8_metadata($top_section, "Plugin", "$self->{'plugin_type'}");
145    $doc_obj->add_utf8_metadata($top_section, "FileSize", (-s $filename_full_path));
146
147    my $plugin_filename_encoding = $self->{'filename_encoding'};
148    my $filename_encoding = $self->deduce_filename_encoding($file,$metadata,$plugin_filename_encoding);
149    $self->set_Source_metadata($doc_obj, $filename_full_path, $filename_encoding);
150
151    $doc_obj->add_utf8_metadata($top_section, "Language", $language);
152    $doc_obj->add_utf8_metadata($top_section, "Encoding", $content_encoding);
153   
154    # read in file ($text will be in utf8)
155    my $text = "";
156    $self->read_file ($filename_full_path, $content_encoding, $language, \$text);
157
158    if (!length ($text)) {
159    if ($gli) {
160        print STDERR "<ProcessingError n='$file' r='File contains no text'>\n";
161    }
162    gsprintf($outhandle, "$self->{'plugin_type'}: {ReadTextFile.file_has_no_text}\n", $filename_full_path) if $self->{'verbosity'};
163
164    my $failhandle = $self->{'failhandle'};
165    gsprintf($failhandle, "$file: " . ref($self) . ": {ReadTextFile.empty_file}\n");
166    # print $failhandle "$file: " . ref($self) . ": file contains no text\n";
167    $self->{'num_not_processed'} ++;
168
169    return (0,undef); # what should we return here?? error but don't want to pass it on
170    }
171   
172    # do plugin specific processing of doc_obj
173    unless (defined ($self->process (\$text, $pluginfo, $base_dir, $file, $metadata, $doc_obj, $gli))) {
174    $text = '';
175    undef $text;
176    print STDERR "<ProcessingError n='$file'>\n" if ($gli);
177    return (-1,undef);
178    }
179    $text='';
180    undef $text;
181   
182    # include any metadata passed in from previous plugins
183    # note that this metadata is associated with the top level section
184    $self->add_associated_files($doc_obj, $filename_full_path);
185    $self->extra_metadata ($doc_obj, $top_section, $metadata);
186
187     # do any automatic metadata extraction
188    $self->auto_extract_metadata ($doc_obj);
189
190
191    # if we haven't found any Title so far, assign one
192    $self->title_fallback($doc_obj,$top_section,$filename_no_path);
193
194    $self->add_OID($doc_obj);
195   
196    return (1,$doc_obj);
197}
198
199# uses the multiread package to read in the entire file pointed to
200# by filename and loads the resulting text into $$textref. Input text
201# may be in any of the encodings handled by multiread, output text
202# will be in utf8
203sub read_file {
204    my $self = shift (@_);
205    my ($filename, $encoding, $language, $textref) = @_;
206
207    if (!-r $filename)
208    {
209    my $outhandle = $self->{'outhandle'};
210    gsprintf($outhandle, "{ReadTextFile.read_denied}\n", $filename) if $self->{'verbosity'};
211    # print $outhandle "Read permission denied for $filename\n" if $self->{'verbosity'};
212    return;
213    }
214    $$textref = "";
215    if (!open (FILE, $filename)) {
216    gsprintf(STDERR, "ReadTextFile::read_file {ReadTextFile.could_not_open_for_reading} ($!)\n", $filename);
217    die "\n";
218    }
219     
220    if ($encoding eq "ascii") {
221    # Replace file 'slurp' with faster implementation
222    sysread(FILE, $$textref, -s FILE);
223   
224    # The old slow way of reading in a file
225    #undef $/;
226    #$$textref = <FILE>;
227    #$/ = "\n";
228    } else {
229    my $reader = new multiread();
230    $reader->set_handle ('ReadTextFile::FILE');
231    $reader->set_encoding ($encoding);
232    $reader->read_file ($textref);
233    }
234
235    # At this point $$textref is a binary byte string
236    # => turn it into a Unicode aware string, so full
237    # Unicode aware pattern matching can be used.
238    # For instance: 's/\x{0101}//g' or '[[:upper:]]'
239    #
240
241    $$textref = decode("utf8",$$textref);
242
243    close FILE;
244}
245
246
247# Not currently used
248sub UNUSED_read_file_usingPerlsEncodeModule {
249##sub read_file {
250    my $self = shift (@_);
251    my ($filename, $encoding, $language, $textref) = @_;
252
253    if (!-r $filename)
254    {
255        my $outhandle = $self->{'outhandle'};
256        gsprintf($outhandle, "{ReadTextFile.read_denied}\n", $filename) if $self->{'verbosity'};
257        # print $outhandle "Read permission denied for $filename\n" if $self->{'verbosity'};
258        return;
259    }
260    $$textref = "";
261    if (!open (FILE, $filename)) {
262        gsprintf(STDERR, "ReadTextFile::read_file {ReadTextFile.could_not_open_f
263or_reading} ($!)\n", $filename);
264        die "\n";
265    }
266
267    my $store_slash = $/;
268    undef $/;
269    my $text = <FILE>;
270    $/ = $store_slash;
271
272    $$textref = decode($encoding,$text);
273
274    close FILE;
275}
276
277
278sub read_file_no_decoding {
279    my $self = shift (@_);
280    my ($filename, $textref) = @_;
281
282    if (!-r $filename)
283    {
284    my $outhandle = $self->{'outhandle'};
285    gsprintf($outhandle, "{ReadTextFile.read_denied}\n", $filename) if $self->{'verbosity'};
286    # print $outhandle "Read permission denied for $filename\n" if $self->{'verbosity'};
287    return;
288    }
289    $$textref = "";
290    if (!open (FILE, $filename)) {
291    gsprintf(STDERR, "ReadTextFile::read_file {ReadTextFile.could_not_open_for_reading} ($!)\n", $filename);
292    die "\n";
293    }
294     
295    my $reader = new multiread();
296    $reader->set_handle ('ReadTextFile::FILE');
297    $reader->read_file_no_decoding ($textref);
298   
299    $self->{'reader'} = $reader;
300
301    close FILE;
302}
303
304
305sub decode_text {
306    my $self = shift (@_);
307    my ($raw_text, $encoding, $language, $textref) = @_;
308
309    my $reader = $self->{'reader'};
310    if (!defined $reader) {
311    gsprintf(STDERR, "ReadTextFile::decode_text needs to call ReadTextFile::read_file_no_decoding first\n");
312    }
313    else {
314    $reader->set_encoding($encoding);
315    $reader->decode_text($raw_text,$textref);
316
317    # At this point $$textref is a binary byte string
318    # => turn it into a Unicode aware string, so full
319    # Unicode aware pattern matching can be used.
320    # For instance: 's/\x{0101}//g' or '[[:upper:]]'   
321   
322    $$textref = decode("utf8",$$textref);
323    }
324}
325
326
327sub textcat_get_language_encoding {
328    my $self = shift (@_);
329    my ($filename) = @_;
330
331    $self->{'textcat'} = new ngramj() if (!defined($self->{'textcat'}));
332   
333    my ($language, $encoding, $extracted_encoding);
334    if ($self->{'input_encoding'} eq "auto") {
335        # use textcat to automatically work out the input encoding and language
336        ($language, $encoding) = $self->get_language_encoding ($filename);
337    } elsif ($self->{'extract_language'}) {
338    # use textcat to get language metadata
339        ($language, $extracted_encoding) = $self->get_language_encoding ($filename);
340        $encoding = $self->{'input_encoding'};
341    # don't print this message for english... english in utf8 is identical
342    # to english in iso-8859-1 (except for some punctuation). We don't have
343    # a language model for en_utf8, so textcat always says iso-8859-1!
344        if ($extracted_encoding ne $encoding && $language ne "en" && $self->{'verbosity'}) {
345        my $plugin_name = ref ($self);
346        my $outhandle = $self->{'outhandle'};
347        gsprintf($outhandle, "$plugin_name: {ReadTextFile.wrong_encoding}\n", $filename, $encoding, $extracted_encoding);
348        }
349    } else {
350        $language = $self->{'default_language'};
351        $encoding = $self->{'input_encoding'};
352    }
353   
354#    print STDERR "**** language encoding of contents of file $filename:\n\t****$language $encoding\n";
355
356    return ($language, $encoding);
357}
358
359
360# Uses textcat to work out the encoding and language of the text in
361# $filename. All html tags are removed before processing.
362# returns an array containing "language" and "encoding"
363sub get_language_encoding {
364    my $self = shift (@_);
365    my ($filename) = @_;
366    my $outhandle = $self->{'outhandle'};
367    my $unicode_format = "";
368    my $best_language = "";
369    my $best_encoding = "";
370   
371
372    # read in file
373    if (!open (FILE, $filename)) {
374    gsprintf(STDERR, "ReadTextFile::get_language_encoding {ReadTextFile.could_not_open_for_reading} ($!)\n", $filename);
375    # this is a pretty bad error, but try to continue anyway
376    return ($self->{'default_language'}, $self->{'input_encoding'});
377    }
378    undef $/;
379    my $text = <FILE>;
380    $/ = "\n";
381    close FILE;
382
383    # check if first few bytes have a Byte Order Marker
384    my $bom=substr($text,0,2); # check 16bit unicode
385    if ($bom eq "\xff\xfe") { # little endian 16bit unicode
386    $unicode_format="unicode";
387    } elsif ($bom eq "\xfe\xff") { # big endian 16bit unicode
388    $unicode_format="unicode";
389    } else {
390    $bom=substr($text,0,3); # check utf-8
391    if ($bom eq "\xef\xbb\xbf") { # utf-8 coded FEFF bom
392        $unicode_format="utf8";
393#   } elsif ($bom eq "\xef\xbf\xbe") { # utf-8 coded FFFE bom. Error!?
394#       $unicode_format="utf8";
395    }
396    }
397   
398    my $found_html_encoding = 0;
399    # handle html files specially
400    # XXX this doesn't match plugins derived from HTMLPlug (except ConvertTo)
401    if (ref($self) eq 'HTMLPlugin' ||
402    (exists $self->{'converted_to'} && $self->{'converted_to'} eq 'HTML')){
403
404    # remove comments in head, including multiline ones, so that we don't match on
405    # inactive tags (those that are nested inside comments)
406    my ($head) = ($text =~ m/<head>(.*)<\/head>/si);
407    $head = "" unless defined $head; # some files are not proper HTML eg php files
408    $head =~ s/<!--.*?-->//sg;
409
410    # remove <title>stuff</title> -- as titles tend often to be in English
411    # for foreign language documents
412    $text =~ s!<title>.*?</title>!!si;
413
414    # see if this html file specifies its encoding
415    if ($text =~ /^<\?xml.*encoding="(.+?)"/) {
416        $best_encoding = $1;
417    }
418    # check the meta http-equiv charset tag
419    elsif ($head =~ m/<meta http-equiv.*content-type.*charset=(.+?)\"/si) {           
420        $best_encoding = $1;
421    }
422    if ($best_encoding) { # we extracted an encoding
423        $best_encoding =~ s/-+/_/g;
424        $best_encoding = lc($best_encoding); # lowercase
425        if ($best_encoding eq "utf_8") { $best_encoding = "utf8" }
426        $found_html_encoding = 1;
427        # We shouldn't be modifying this here!!
428        #$self->{'input_encoding'} = $best_encoding;
429    }
430       
431    # remove all HTML tags
432    $text =~ s/<[^>]*>//sg;
433    }
434
435    # don't need to do textcat if we know the encoding now AND don't need to extract language
436    if($found_html_encoding && !$self->{'extract_language'}) { # encoding specified in html file
437    $best_language = $self->{'default_language'};
438    }
439
440    else { # need to use textcat to get either the language, or get both language and encoding
441    $self->{'textcat'} = new textcat() if (!defined($self->{'textcat'}));
442   
443    if($found_html_encoding) { # know encoding, find language by limiting search to known encoding
444        my $results = $self->{'textcat'}->classify_contents_for_encoding(\$text, $filename, $best_encoding);
445       
446        my $language;
447        ($language) = $results->[0] =~ m/^([^-]*)(?:-(?:.*))?$/ if (scalar @$results > 0);
448
449        if (!defined $language || scalar @$results > 3) {
450        # if there were too many results even when restricting results by encoding,
451        # or if there were no results, use default language with the known encoding
452        $best_language = $self->use_default_language($filename);
453        }
454        else { # fewer than 3 results means textcat is more certain, use the first result
455        $best_language = $language;     
456        }
457    }
458    else { # don't know encoding or language yet, therefore we use textcat
459        my $results = $self->{'textcat'}->classify_contents(\$text, $filename);
460       
461        # if textcat returns 3 or less possibilities we'll use the first one in the list
462        if (scalar @$results <= 3) { # results will be > 0 when we don't constrain textcat by an encoding
463        my ($language, $encoding) = $results->[0] =~ m/^([^-]*)(?:-(.*))?$/;
464
465        $language = $self->use_default_language($filename) unless defined $language;
466        $encoding = $self->use_default_encoding($filename) unless defined $encoding;
467
468        $best_language = $language;
469        $best_encoding = $encoding;
470        }
471        else { # if (scalar @$results > 3) {
472        if ($unicode_format) { # in case the first had a BOM
473            $best_encoding=$unicode_format;
474        }
475        else {
476            # Find the most frequent encoding in the textcat results returned
477            # Returns "" if there's no encoding more frequent than another
478            $best_encoding = $self->{'textcat'}->most_frequent_encoding($results);
479        }
480       
481        if ($best_encoding eq "") { # encoding still not set, use defaults
482            $best_language = $self->use_default_language($filename);
483            $best_encoding = $self->use_default_encoding($filename);
484        }
485        elsif (!$self->{'extract_language'}) { # know encoding but don't need to discover language
486            $best_language = $self->use_default_language($filename);
487        }
488        else { # textcat again using the most frequent encoding or the $unicode_format set above
489            $results = $self->{'textcat'}->classify_contents_for_encoding(\$text, $filename, $best_encoding);
490            my $language;
491            ($language) = $results->[0] =~ m/^([^-]*)(?:-(.*))?$/ if (scalar @$results > 0);
492            if (!defined $language || scalar @$results > 3) {
493            # if no result or too many results, use default language for the encoding previously found
494            $best_language = $self->use_default_language($filename);
495            }
496            else { # fewer than 3 results, use the language of the first result
497            $best_language = $language;
498            }
499        }
500        }
501    }
502    }
503
504    if($best_encoding eq "" || $best_language eq "") {
505    print STDERR "****Shouldn't happen: encoding and/or language still not set. Using defaults.\n";
506    $best_encoding = $self->use_default_encoding($filename) if $best_encoding eq "";
507    $best_language = $self->use_default_language($filename) if $best_language eq "";
508    }
509#    print STDERR "****Content language: $best_language; Encoding: $best_encoding.\n";
510
511
512    if ($best_encoding =~ /^iso_8859/ && &unicode::check_is_utf8($text)) {
513    # the text is valid utf8, so assume that's the real encoding
514    # (since textcat is based on probabilities)
515    $best_encoding = 'utf8';
516    }
517
518    # check for equivalents where textcat doesn't have some encodings...
519    # eg MS versions of standard encodings
520    if ($best_encoding =~ /^iso_8859_(\d+)/) {
521    my $iso = $1; # which variant of the iso standard?
522    # iso-8859 sets don't use chars 0x80-0x9f, windows codepages do
523    if ($text =~ /[\x80-\x9f]/) {
524        # Western Europe
525        if ($iso == 1 or $iso == 15) { $best_encoding = 'windows_1252' }
526        elsif ($iso == 2) {$best_encoding = 'windows_1250'} # Central Europe
527        elsif ($iso == 5) {$best_encoding = 'windows_1251'} # Cyrillic
528        elsif ($iso == 6) {$best_encoding = 'windows_1256'} # Arabic
529        elsif ($iso == 7) {$best_encoding = 'windows_1253'} # Greek
530        elsif ($iso == 8) {$best_encoding = 'windows_1255'} # Hebrew
531        elsif ($iso == 9) {$best_encoding = 'windows_1254'} # Turkish
532    }
533    }
534
535    if ($best_encoding !~ /^(ascii|utf8|unicode)$/ &&
536    !defined $encodings::encodings->{$best_encoding}) {
537    if ($self->{'verbosity'}) {
538        gsprintf($outhandle, "ReadTextFile: {ReadTextFile.unsupported_encoding}\n",
539             $filename, $best_encoding, $self->{'default_encoding'});
540    }
541    $best_encoding = $self->{'default_encoding'};
542    }
543
544    return ($best_language, $best_encoding);
545}
546
547
548
549# Uses java ngram solution to work out the language of the text in
550# $filename. Fall back on textcat to to the character encoding
551# All html tags are removed before processing.
552# returns an array containing "language" and "encoding"
553sub get_language_encoding {
554    my $self = shift (@_);
555    my ($filename) = @_;
556    my $outhandle = $self->{'outhandle'};
557    my $unicode_format = "";
558    my $best_language = "";
559    my $best_encoding = "";
560   
561
562    # read in file
563    if (!open (FILE, $filename)) {
564    gsprintf(STDERR, "ReadTextFile::java_ngram_get_language_encoding {ReadTextFile.could_not_open_for_reading} ($!)\n", $filename);
565    # this is a pretty bad error, but try to continue anyway
566    return ($self->{'default_language'}, $self->{'input_encoding'});
567    }
568    undef $/;
569    my $text = <FILE>;
570    $/ = "\n";
571    close FILE;
572
573    # check if first few bytes have a Byte Order Marker
574    my $bom=substr($text,0,2); # check 16bit unicode
575    if ($bom eq "\xff\xfe") { # little endian 16bit unicode
576    $unicode_format="unicode";
577    } elsif ($bom eq "\xfe\xff") { # big endian 16bit unicode
578    $unicode_format="unicode";
579    } else {
580    $bom=substr($text,0,3); # check utf-8
581    if ($bom eq "\xef\xbb\xbf") { # utf-8 coded FEFF bom
582        $unicode_format="utf8";
583#   } elsif ($bom eq "\xef\xbf\xbe") { # utf-8 coded FFFE bom. Error!?
584#       $unicode_format="utf8";
585    }
586    }
587   
588    my $found_html_encoding = 0;
589    # handle html files specially
590    # XXX this doesn't match plugins derived from HTMLPlug (except ConvertTo)
591    if (ref($self) eq 'HTMLPlugin' ||
592    (exists $self->{'converted_to'} && $self->{'converted_to'} eq 'HTML')){
593
594    # remove comments in head, including multiline ones, so that we don't match on
595    # inactive tags (those that are nested inside comments)
596    my ($head) = ($text =~ m/<head>(.*)<\/head>/si);
597    $head = "" unless defined $head; # some files are not proper HTML eg php files
598    $head =~ s/<!--.*?-->//sg;
599
600    # remove <title>stuff</title> -- as titles tend often to be in English
601    # for foreign language documents
602    $text =~ s!<title>.*?</title>!!si;
603
604    # see if this html file specifies its encoding
605    if ($text =~ /^<\?xml.*encoding="(.+?)"/) {
606        $best_encoding = $1;
607    }
608    # check the meta http-equiv charset tag
609    elsif ($head =~ m/<meta http-equiv.*content-type.*charset=(.+?)\"/si) {           
610        $best_encoding = $1;
611    }
612    if ($best_encoding) { # we extracted an encoding
613        $best_encoding =~ s/-+/_/g;
614        $best_encoding = lc($best_encoding); # lowercase
615        if ($best_encoding eq "utf_8") { $best_encoding = "utf8" }
616        $found_html_encoding = 1;
617        # We shouldn't be modifying this here!!
618        #$self->{'input_encoding'} = $best_encoding;
619    }
620       
621    # remove all HTML tags
622    $text =~ s/<[^>]*>//sg;
623    }
624
625    # don't need to do textcat if we know the encoding now AND don't need to extract language
626    if($found_html_encoding && !$self->{'extract_language'}) { # encoding specified in html file
627    $best_language = $self->{'default_language'};
628    }
629
630    else { # need to use textcat to get either the language, or get both language and encoding
631    $self->{'ngramj'} = new ngramj() if (!defined($self->{'ngramj'}));
632   
633    if($found_html_encoding) { # know encoding, find language by limiting search to known encoding
634        my $results = $self->{'ngramj'}->classify_contents_for_encoding(\$text, $filename, $best_encoding);
635       
636        my $language;
637        ($language) = $results->[0] =~ m/^([^-]*)(?:-(?:.*))?$/ if (scalar @$results > 0);
638
639        if (!defined $language || scalar @$results > 3) {
640        # if there were too many results even when restricting results by encoding,
641        # or if there were no results, use default language with the known encoding
642        $best_language = $self->use_default_language($filename);
643        }
644        else { # fewer than 3 results means textcat is more certain, use the first result
645        $best_language = $language;     
646        }
647    }
648    else { # don't know encoding or language yet, therefore we use textcat
649        my $results = $self->{'ngramj'}->classify_contents(\$text, $filename);
650       
651        # if textcat returns 3 or less possibilities we'll use the first one in the list
652        if (scalar @$results <= 3) { # results will be > 0 when we don't constrain textcat by an encoding
653        my ($language, $encoding) = $results->[0] =~ m/^([^-]*)(?:-(.*))?$/;
654
655        $language = $self->use_default_language($filename) unless defined $language;
656        $encoding = $self->use_default_encoding($filename) unless defined $encoding;
657
658        $best_language = $language;
659        $best_encoding = $encoding;
660        }
661        else { # if (scalar @$results > 3) {
662        if ($unicode_format) { # in case the first had a BOM
663            $best_encoding=$unicode_format;
664        }
665        else {
666            # Find the most frequent encoding in the textcat results returned
667            # Returns "" if there's no encoding more frequent than another
668            $best_encoding = $self->{'textcat'}->most_frequent_encoding($results);
669        }
670       
671        if ($best_encoding eq "") { # encoding still not set, use defaults
672            $best_language = $self->use_default_language($filename);
673            $best_encoding = $self->use_default_encoding($filename);
674        }
675        elsif (!$self->{'extract_language'}) { # know encoding but don't need to discover language
676            $best_language = $self->use_default_language($filename);
677        }
678        else { # textcat again using the most frequent encoding or the $unicode_format set above
679            $results = $self->{'textcat'}->classify_contents_for_encoding(\$text, $filename, $best_encoding);
680            my $language;
681            ($language) = $results->[0] =~ m/^([^-]*)(?:-(.*))?$/ if (scalar @$results > 0);
682            if (!defined $language || scalar @$results > 3) {
683            # if no result or too many results, use default language for the encoding previously found
684            $best_language = $self->use_default_language($filename);
685            }
686            else { # fewer than 3 results, use the language of the first result
687            $best_language = $language;
688            }
689        }
690        }
691    }
692    }
693
694    if($best_encoding eq "" || $best_language eq "") {
695    print STDERR "****Shouldn't happen: encoding and/or language still not set. Using defaults.\n";
696    $best_encoding = $self->use_default_encoding($filename) if $best_encoding eq "";
697    $best_language = $self->use_default_language($filename) if $best_language eq "";
698    }
699#    print STDERR "****Content language: $best_language; Encoding: $best_encoding.\n";
700
701
702    if ($best_encoding =~ /^iso_8859/ && &unicode::check_is_utf8($text)) {
703    # the text is valid utf8, so assume that's the real encoding
704    # (since textcat is based on probabilities)
705    $best_encoding = 'utf8';
706    }
707
708    # check for equivalents where textcat doesn't have some encodings...
709    # eg MS versions of standard encodings
710    if ($best_encoding =~ /^iso_8859_(\d+)/) {
711    my $iso = $1; # which variant of the iso standard?
712    # iso-8859 sets don't use chars 0x80-0x9f, windows codepages do
713    if ($text =~ /[\x80-\x9f]/) {
714        # Western Europe
715        if ($iso == 1 or $iso == 15) { $best_encoding = 'windows_1252' }
716        elsif ($iso == 2) {$best_encoding = 'windows_1250'} # Central Europe
717        elsif ($iso == 5) {$best_encoding = 'windows_1251'} # Cyrillic
718        elsif ($iso == 6) {$best_encoding = 'windows_1256'} # Arabic
719        elsif ($iso == 7) {$best_encoding = 'windows_1253'} # Greek
720        elsif ($iso == 8) {$best_encoding = 'windows_1255'} # Hebrew
721        elsif ($iso == 9) {$best_encoding = 'windows_1254'} # Turkish
722    }
723    }
724
725    if ($best_encoding !~ /^(ascii|utf8|unicode)$/ &&
726    !defined $encodings::encodings->{$best_encoding}) {
727    if ($self->{'verbosity'}) {
728        gsprintf($outhandle, "ReadTextFile: {ReadTextFile.unsupported_encoding}\n",
729             $filename, $best_encoding, $self->{'default_encoding'});
730    }
731    $best_encoding = $self->{'default_encoding'};
732    }
733
734    return ($best_language, $best_encoding);
735}
736
737
738
739
740sub use_default_language {
741    my $self = shift (@_);
742    my ($filename) = @_;
743
744    if ($self->{'verbosity'}>2) {
745    gsprintf($self->{'outhandle'},
746         "ReadTextFile: {ReadTextFile.could_not_extract_language}\n",
747         $filename, $self->{'default_language'});
748    }
749    return $self->{'default_language'};
750}
751
752sub use_default_encoding {
753    my $self = shift (@_);
754    my ($filename) = @_;
755
756    if ($self->{'verbosity'}>2) {
757    gsprintf($self->{'outhandle'},
758         "ReadTextFile: {ReadTextFile.could_not_extract_encoding}\n",
759         $filename, $self->{'default_encoding'});
760    }
761    return $self->{'default_encoding'};
762}
763
764# Overridden by exploding plugins (eg. ISISPlug)
765sub clean_up_after_exploding
766{
767    my $self = shift(@_);
768}
769
770
7711;
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