source: main/trunk/greenstone2/perllib/plugins/ReadTextFile.pm@ 22857

Last change on this file since 22857 was 22857, checked in by davidb, 14 years ago

Further adjustments to our reading in of text files/data to be Unicode aware. These changes address the issue of when the data being read in is in a different encoding. The key 'problem' was that the (now) Unicode aware was being erroneously being re-encoded within HTMLPlugin
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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 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 print $outhandle "$self->{'plugin_type'} processing $file\n"
125 if $self->{'verbosity'} > 1;
126
127 my ($filename_full_path, $filename_no_path) = &util::get_full_filenames($base_dir, $file);
128
129 # Do encoding stuff
130 my ($language, $encoding) = $self->textcat_get_language_encoding ($filename_full_path);
131 if ($self->{'verbosity'} > 2) {
132 print $outhandle "ReadTextFile: reading $file as ($encoding,$language)\n";
133 }
134
135 # create a new document
136 my $doc_obj = new doc ($filename_full_path, "indexed_doc", $self->{'file_rename_method'});
137 my $top_section = $doc_obj->get_top_section();
138
139 # this should look at the plugin option too...
140 $doc_obj->add_utf8_metadata($top_section, "Plugin", "$self->{'plugin_type'}");
141 $doc_obj->add_utf8_metadata($top_section, "FileSize", (-s $filename_full_path));
142 $self->set_Source_metadata($doc_obj, $filename_no_path, $encoding);
143
144 $doc_obj->add_utf8_metadata($top_section, "Language", $language);
145 $doc_obj->add_utf8_metadata($top_section, "Encoding", $encoding);
146
147 # read in file ($text will be in utf8)
148 my $text = "";
149 $self->read_file ($filename_full_path, $encoding, $language, \$text);
150
151 if (!length ($text)) {
152 if ($gli) {
153 print STDERR "<ProcessingError n='$file' r='File contains no text'>\n";
154 }
155 gsprintf($outhandle, "$self->{'plugin_type'}: {ReadTextFile.file_has_no_text}\n", $filename_full_path) if $self->{'verbosity'};
156
157 my $failhandle = $self->{'failhandle'};
158 gsprintf($failhandle, "$file: " . ref($self) . ": {ReadTextFile.empty_file}\n");
159 # print $failhandle "$file: " . ref($self) . ": file contains no text\n";
160 $self->{'num_not_processed'} ++;
161
162 return (0,undef); # what should we return here?? error but don't want to pass it on
163 }
164
165 # do plugin specific processing of doc_obj
166 unless (defined ($self->process (\$text, $pluginfo, $base_dir, $file, $metadata, $doc_obj, $gli))) {
167 $text = '';
168 undef $text;
169 print STDERR "<ProcessingError n='$file'>\n" if ($gli);
170 return (-1,undef);
171 }
172 $text='';
173 undef $text;
174
175 # include any metadata passed in from previous plugins
176 # note that this metadata is associated with the top level section
177 $self->add_associated_files($doc_obj, $filename_full_path);
178 $self->extra_metadata ($doc_obj, $top_section, $metadata);
179
180 # do any automatic metadata extraction
181 $self->auto_extract_metadata ($doc_obj);
182
183
184 # if we haven't found any Title so far, assign one
185 $self->title_fallback($doc_obj,$top_section,$filename_no_path);
186
187 $self->add_OID($doc_obj);
188
189 return (1,$doc_obj);
190}
191
192# uses the multiread package to read in the entire file pointed to
193# by filename and loads the resulting text into $$textref. Input text
194# may be in any of the encodings handled by multiread, output text
195# will be in utf8
196sub read_file {
197 my $self = shift (@_);
198 my ($filename, $encoding, $language, $textref) = @_;
199
200 if (!-r $filename)
201 {
202 my $outhandle = $self->{'outhandle'};
203 gsprintf($outhandle, "{ReadTextFile.read_denied}\n", $filename) if $self->{'verbosity'};
204 # print $outhandle "Read permission denied for $filename\n" if $self->{'verbosity'};
205 return;
206 }
207 $$textref = "";
208 if (!open (FILE, $filename)) {
209 gsprintf(STDERR, "ReadTextFile::read_file {ReadTextFile.could_not_open_for_reading} ($!)\n", $filename);
210 die "\n";
211 }
212
213 if ($encoding eq "ascii") {
214 undef $/;
215 $$textref = <FILE>;
216 $/ = "\n";
217 } else {
218 my $reader = new multiread();
219 $reader->set_handle ('ReadTextFile::FILE');
220 $reader->set_encoding ($encoding);
221 $reader->read_file ($textref);
222 }
223
224 # At this point $$textref is a binary byte string
225 # => turn it into a Unicode aware string, so full
226 # Unicode aware pattern matching can be used.
227 # For instance: 's/\x{0101}//g' or '[[:upper:]]'
228 #
229
230 $$textref = decode("utf8",$$textref);
231
232 close FILE;
233}
234
235
236# Not currently used
237sub UNUSED_read_file_usingPerlsEncodeModule {
238##sub read_file {
239 my $self = shift (@_);
240 my ($filename, $encoding, $language, $textref) = @_;
241
242 if (!-r $filename)
243 {
244 my $outhandle = $self->{'outhandle'};
245 gsprintf($outhandle, "{ReadTextFile.read_denied}\n", $filename) if $self->{'verbosity'};
246 # print $outhandle "Read permission denied for $filename\n" if $self->{'verbosity'};
247 return;
248 }
249 $$textref = "";
250 if (!open (FILE, $filename)) {
251 gsprintf(STDERR, "ReadTextFile::read_file {ReadTextFile.could_not_open_f
252or_reading} ($!)\n", $filename);
253 die "\n";
254 }
255
256 my $store_slash = $/;
257 undef $/;
258 my $text = <FILE>;
259 $/ = $store_slash;
260
261 $$textref = decode($encoding,$text);
262
263 close FILE;
264}
265
266
267sub read_file_no_decoding {
268 my $self = shift (@_);
269 my ($filename, $textref) = @_;
270
271 if (!-r $filename)
272 {
273 my $outhandle = $self->{'outhandle'};
274 gsprintf($outhandle, "{ReadTextFile.read_denied}\n", $filename) if $self->{'verbosity'};
275 # print $outhandle "Read permission denied for $filename\n" if $self->{'verbosity'};
276 return;
277 }
278 $$textref = "";
279 if (!open (FILE, $filename)) {
280 gsprintf(STDERR, "ReadTextFile::read_file {ReadTextFile.could_not_open_for_reading} ($!)\n", $filename);
281 die "\n";
282 }
283
284 my $reader = new multiread();
285 $reader->set_handle ('ReadTextFile::FILE');
286 $reader->read_file_no_decoding ($textref);
287
288 $self->{'reader'} = $reader;
289
290 close FILE;
291}
292
293
294sub decode_text {
295 my $self = shift (@_);
296 my ($raw_text, $encoding, $language, $textref) = @_;
297
298 my $reader = $self->{'reader'};
299 if (!defined $reader) {
300 gsprintf(STDERR, "ReadTextFile::decode_text needs to call ReadTextFile::read_file_no_decoding first\n");
301 }
302 else {
303 $reader->set_encoding($encoding);
304 $reader->decode_text($raw_text,$textref);
305 }
306}
307
308
309sub textcat_get_language_encoding {
310 my $self = shift (@_);
311 my ($filename) = @_;
312
313 my ($language, $encoding, $extracted_encoding);
314 if ($self->{'input_encoding'} eq "auto") {
315 # use textcat to automatically work out the input encoding and language
316 ($language, $encoding) = $self->get_language_encoding ($filename);
317 } elsif ($self->{'extract_language'}) {
318 # use textcat to get language metadata
319 ($language, $extracted_encoding) = $self->get_language_encoding ($filename);
320 $encoding = $self->{'input_encoding'};
321 # don't print this message for english... english in utf8 is identical
322 # to english in iso-8859-1 (except for some punctuation). We don't have
323 # a language model for en_utf8, so textcat always says iso-8859-1!
324 if ($extracted_encoding ne $encoding && $language ne "en" && $self->{'verbosity'}) {
325 my $plugin_name = ref ($self);
326 my $outhandle = $self->{'outhandle'};
327 gsprintf($outhandle, "$plugin_name: {ReadTextFile.wrong_encoding}\n", $filename, $encoding, $extracted_encoding);
328 }
329 } else {
330 $language = $self->{'default_language'};
331 $encoding = $self->{'input_encoding'};
332 }
333
334# print STDERR "**** language encoding of contents of file $filename:\n\t****$language $encoding\n";
335
336 return ($language, $encoding);
337}
338
339
340# Uses textcat to work out the encoding and language of the text in
341# $filename. All html tags are removed before processing.
342# returns an array containing "language" and "encoding"
343sub get_language_encoding {
344 my $self = shift (@_);
345 my ($filename) = @_;
346 my $outhandle = $self->{'outhandle'};
347 my $unicode_format = "";
348 my $best_language = "";
349 my $best_encoding = "";
350
351
352 # read in file
353 if (!open (FILE, $filename)) {
354 gsprintf(STDERR, "ReadTextFile::get_language_encoding {ReadTextFile.could_not_open_for_reading} ($!)\n", $filename);
355 # this is a pretty bad error, but try to continue anyway
356 return ($self->{'default_language'}, $self->{'input_encoding'});
357 }
358 undef $/;
359 my $text = <FILE>;
360 $/ = "\n";
361 close FILE;
362
363 # check if first few bytes have a Byte Order Marker
364 my $bom=substr($text,0,2); # check 16bit unicode
365 if ($bom eq "\xff\xfe") { # little endian 16bit unicode
366 $unicode_format="unicode";
367 } elsif ($bom eq "\xfe\xff") { # big endian 16bit unicode
368 $unicode_format="unicode";
369 } else {
370 $bom=substr($text,0,3); # check utf-8
371 if ($bom eq "\xef\xbb\xbf") { # utf-8 coded FEFF bom
372 $unicode_format="utf8";
373# } elsif ($bom eq "\xef\xbf\xbe") { # utf-8 coded FFFE bom. Error!?
374# $unicode_format="utf8";
375 }
376 }
377
378 my $found_html_encoding = 0;
379 # handle html files specially
380 # XXX this doesn't match plugins derived from HTMLPlug (except ConvertTo)
381 if (ref($self) eq 'HTMLPlugin' ||
382 (exists $self->{'converted_to'} && $self->{'converted_to'} eq 'HTML')){
383
384 # remove comments in head, including multiline ones, so that we don't match on
385 # inactive tags (those that are nested inside comments)
386 my ($head) = ($text =~ m/<head>(.*)<\/head>/si);
387 $head = "" unless defined $head; # some files are not proper HTML eg php files
388 $head =~ s/<!--.*?-->//sg;
389
390 # remove <title>stuff</title> -- as titles tend often to be in English
391 # for foreign language documents
392 $text =~ s!<title>.*?</title>!!si;
393
394 # see if this html file specifies its encoding
395 if ($text =~ /^<\?xml.*encoding="(.+?)"/) {
396 $best_encoding = $1;
397 }
398 # check the meta http-equiv charset tag
399 elsif ($head =~ m/<meta http-equiv.*content-type.*charset=(.+?)\"/si) {
400 $best_encoding = $1;
401 }
402 if ($best_encoding) { # we extracted an encoding
403 $best_encoding =~ s/-+/_/g;
404 $best_encoding = lc($best_encoding); # lowercase
405 if ($best_encoding eq "utf_8") { $best_encoding = "utf8" }
406 $found_html_encoding = 1;
407 # We shouldn't be modifying this here!!
408 #$self->{'input_encoding'} = $best_encoding;
409 }
410
411 # remove all HTML tags
412 $text =~ s/<[^>]*>//sg;
413 }
414
415 # don't need to do textcat if we know the encoding now AND don't need to extract language
416 if($found_html_encoding && !$self->{'extract_language'}) { # encoding specified in html file
417 $best_language = $self->{'default_language'};
418 }
419
420 else { # need to use textcat to get either the language, or get both language and encoding
421 $self->{'textcat'} = new textcat() if (!defined($self->{'textcat'}));
422
423 if($found_html_encoding) { # know encoding, find language by limiting search to known encoding
424 my $results = $self->{'textcat'}->classify_contents_for_encoding(\$text, $filename, $best_encoding);
425
426 my $language;
427 ($language) = $results->[0] =~ m/^([^-]*)(?:-(?:.*))?$/ if (scalar @$results > 0);
428
429 if (!defined $language || scalar @$results > 3) {
430 # if there were too many results even when restricting results by encoding,
431 # or if there were no results, use default language with the known encoding
432 $best_language = $self->use_default_language($filename);
433 }
434 else { # fewer than 3 results means textcat is more certain, use the first result
435 $best_language = $language;
436 }
437 }
438 else { # don't know encoding or language yet, therefore we use textcat
439 my $results = $self->{'textcat'}->classify_contents(\$text, $filename);
440
441 # if textcat returns 3 or less possibilities we'll use the first one in the list
442 if (scalar @$results <= 3) { # results will be > 0 when we don't constrain textcat by an encoding
443 my ($language, $encoding) = $results->[0] =~ m/^([^-]*)(?:-(.*))?$/;
444
445 $language = $self->use_default_language($filename) unless defined $language;
446 $encoding = $self->use_default_encoding($filename) unless defined $encoding;
447
448 $best_language = $language;
449 $best_encoding = $encoding;
450 }
451 else { # if (scalar @$results > 3) {
452 if ($unicode_format) { # in case the first had a BOM
453 $best_encoding=$unicode_format;
454 }
455 else {
456 # Find the most frequent encoding in the textcat results returned
457 # Returns "" if there's no encoding more frequent than another
458 $best_encoding = $self->{'textcat'}->most_frequent_encoding($results);
459 }
460
461 if ($best_encoding eq "") { # encoding still not set, use defaults
462 $best_language = $self->use_default_language($filename);
463 $best_encoding = $self->use_default_encoding($filename);
464 }
465 elsif (!$self->{'extract_language'}) { # know encoding but don't need to discover language
466 $best_language = $self->use_default_language($filename);
467 }
468 else { # textcat again using the most frequent encoding or the $unicode_format set above
469 $results = $self->{'textcat'}->classify_contents_for_encoding(\$text, $filename, $best_encoding);
470 my $language;
471 ($language) = $results->[0] =~ m/^([^-]*)(?:-(.*))?$/ if (scalar @$results > 0);
472 if (!defined $language || scalar @$results > 3) {
473 # if no result or too many results, use default language for the encoding previously found
474 $best_language = $self->use_default_language($filename);
475 }
476 else { # fewer than 3 results, use the language of the first result
477 $best_language = $language;
478 }
479 }
480 }
481 }
482 }
483
484 if($best_encoding eq "" || $best_language eq "") {
485 print STDERR "****Shouldn't happen: encoding and/or language still not set. Using defaults.\n";
486 $best_encoding = $self->use_default_encoding($filename) if $best_encoding eq "";
487 $best_language = $self->use_default_language($filename) if $best_language eq "";
488 }
489# print STDERR "****Content language: $best_language; Encoding: $best_encoding.\n";
490
491
492 if ($best_encoding =~ /^iso_8859/ && &unicode::check_is_utf8($text)) {
493 # the text is valid utf8, so assume that's the real encoding
494 # (since textcat is based on probabilities)
495 $best_encoding = 'utf8';
496 }
497
498 # check for equivalents where textcat doesn't have some encodings...
499 # eg MS versions of standard encodings
500 if ($best_encoding =~ /^iso_8859_(\d+)/) {
501 my $iso = $1; # which variant of the iso standard?
502 # iso-8859 sets don't use chars 0x80-0x9f, windows codepages do
503 if ($text =~ /[\x80-\x9f]/) {
504 # Western Europe
505 if ($iso == 1 or $iso == 15) { $best_encoding = 'windows_1252' }
506 elsif ($iso == 2) {$best_encoding = 'windows_1250'} # Central Europe
507 elsif ($iso == 5) {$best_encoding = 'windows_1251'} # Cyrillic
508 elsif ($iso == 6) {$best_encoding = 'windows_1256'} # Arabic
509 elsif ($iso == 7) {$best_encoding = 'windows_1253'} # Greek
510 elsif ($iso == 8) {$best_encoding = 'windows_1255'} # Hebrew
511 elsif ($iso == 9) {$best_encoding = 'windows_1254'} # Turkish
512 }
513 }
514
515 if ($best_encoding !~ /^(ascii|utf8|unicode)$/ &&
516 !defined $encodings::encodings->{$best_encoding}) {
517 if ($self->{'verbosity'}) {
518 gsprintf($outhandle, "ReadTextFile: {ReadTextFile.unsupported_encoding}\n",
519 $filename, $best_encoding, $self->{'default_encoding'});
520 }
521 $best_encoding = $self->{'default_encoding'};
522 }
523
524 return ($best_language, $best_encoding);
525}
526
527
528sub use_default_language {
529 my $self = shift (@_);
530 my ($filename) = @_;
531
532 if ($self->{'verbosity'}>2) {
533 gsprintf($self->{'outhandle'},
534 "ReadTextFile: {ReadTextFile.could_not_extract_language}\n",
535 $filename, $self->{'default_language'});
536 }
537 return $self->{'default_language'};
538}
539
540sub use_default_encoding {
541 my $self = shift (@_);
542 my ($filename) = @_;
543
544 if ($self->{'verbosity'}>2) {
545 gsprintf($self->{'outhandle'},
546 "ReadTextFile: {ReadTextFile.could_not_extract_encoding}\n",
547 $filename, $self->{'default_encoding'});
548 }
549 return $self->{'default_encoding'};
550}
551
552# Overridden by exploding plugins (eg. ISISPlug)
553sub clean_up_after_exploding
554{
555 my $self = shift(@_);
556}
557
558
5591;
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