root/gsdl/trunk/perllib/unicode.pm @ 18338

Revision 18338, 17.5 KB (checked in by ak19, 11 years ago)

Moved the line of code that replaced spaces with underscores to the subroutine util::rename_file, since this replacement ought to be done not only when url_encoding but also when using base64 encoding.

  • Property svn:executable set to *
  • Property svn:keywords set to Author Date Id Revision
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1###########################################################################
2#
3# unicode.pm --
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) 1999-2004 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
26# useful functions for dealing with Unicode
27
28# Unicode strings are stored as arrays of scalars as perl
29# lacks characters are 8-bit (currently)
30
31package unicode;
32
33eval {require bytes};
34
35use encodings;
36use strict;
37use util;
38
39no strict 'refs';
40
41# ascii2unicode takes an (extended) ascii string (ISO-8859-1)
42# and returns a unicode array.
43sub ascii2unicode {
44    my ($in) = @_;
45    my $out = [];
46
47    my $i = 0;
48    my $len = length($in);
49    while ($i < $len) {
50    push (@$out, ord(substr ($in, $i, 1)));
51    $i++;
52    }
53
54    return $out;
55}
56
57# ascii2utf8 takes a reference to an (extended) ascii string and returns a
58# UTF-8 encoded string. This is just a faster version of
59# "&unicode2utf8(&ascii2unicode($str));"
60# "Extended ascii" really means "iso_8859_1"
61sub ascii2utf8 {
62    my ($in) = @_;
63    my $out = "";
64
65    if (!defined($in)|| !defined($$in)) {
66    return $out;
67    }
68
69    my ($c);
70    my $i = 0;
71    my $len = length($$in);
72    while ($i < $len) {
73    $c = ord (substr ($$in, $i, 1));
74    if ($c < 0x80) {
75        # ascii character
76        $out .= chr ($c);
77
78    } else {
79        # extended ascii character
80        $out .= chr (0xc0 + (($c >> 6) & 0x1f));
81        $out .= chr (0x80 + ($c & 0x3f));
82    }
83    $i++;
84    }
85
86    return $out;
87}
88
89# unicode2utf8 takes a unicode array as input and encodes it
90# using utf-8
91sub unicode2utf8 {
92    my ($in) = @_;
93    my $out = "";
94   
95    foreach my $num (@$in) {
96    next unless defined $num;
97    if ($num < 0x80) {
98        $out .= chr ($num);
99
100    } elsif ($num < 0x800) {
101        $out .= chr (0xc0 + (($num >> 6) & 0x1f));
102        $out .= chr (0x80 + ($num & 0x3f));
103
104    } elsif ($num < 0xFFFF) {
105        $out .= chr (0xe0 + (($num >> 12) & 0xf));
106        $out .= chr (0x80 + (($num >> 6) & 0x3f));
107        $out .= chr (0x80 + ($num & 0x3f));
108
109    } else {
110        # error, don't encode anything
111        die;
112    }
113    }
114    return $out;
115}
116
117# utf82unicode takes a utf-8 string and produces a unicode
118# array
119sub utf82unicode {
120    my ($in) = @_;
121    my $out = [];
122
123    my $i = 0;
124    my ($c1, $c2, $c3);
125    my $len = length($in);
126    while ($i < $len) {
127    if (($c1 = ord(substr ($in, $i, 1))) < 0x80) {
128        # normal ascii character
129        push (@$out, $c1);
130
131    } elsif ($c1 < 0xc0) {
132        # error, was expecting the first byte of an
133        # encoded character. Do nothing.
134
135    } elsif ($c1 < 0xe0 && $i+1 < $len) {
136        # an encoded character with two bytes
137        $c2 = ord (substr ($in, $i+1, 1));
138        if ($c2 >= 0x80 && $c2 < 0xc0) {
139        # everything looks ok
140        push (@$out, ((($c1 & 0x1f) << 6) +
141              ($c2 & 0x3f)));
142        $i++; # gobbled an extra byte
143        }
144
145    } elsif ($c1 < 0xf0 && $i+2 < $len) {
146        # an encoded character with three bytes
147        $c2 = ord (substr ($in, $i+1, 1));
148        $c3 = ord (substr ($in, $i+2, 1));
149        if ($c2 >= 0x80 && $c2 < 0xc0 &&
150        $c3 >= 0x80 && $c3 < 0xc0) {
151        # everything looks ok
152        push (@$out, ((($c1 & 0xf) << 12) +
153              (($c2 & 0x3f) << 6) +
154              ($c3 & 0x3f)));
155
156        $i += 2; # gobbled an extra two bytes
157        }
158
159    } else {
160        # error, only decode Unicode characters not full UCS.
161        # Do nothing.
162    }
163
164    $i++;
165    }
166
167    return $out;
168}
169
170# unicode2ucs2 takes a unicode array and produces a UCS-2
171# unicode string (every two bytes forms a unicode character)
172sub unicode2ucs2 {
173    my ($in) = @_;
174    my $out = "";
175
176    foreach my $num (@$in) {
177    $out .= chr (($num & 0xff00) >> 8);
178    $out .= chr ($num & 0xff);
179    }
180
181    return $out;
182}
183
184# ucs22unicode takes a UCS-2 string and produces a unicode array
185sub ucs22unicode {
186    my ($in) = @_;
187    my $out = [];
188
189    my $i = 0;
190    my $len = length ($in);
191    while ($i+1 < $len) {
192    push (@$out, ord (substr($in, $i, 1)) << 8 +
193          ord (substr($in, $i+1, 1)));
194
195    $i ++;
196    }
197
198    return $out;
199}
200
201# takes a reference to a string and returns a reference to a unicode array
202sub convert2unicode {
203    my ($encoding, $textref) = @_;
204
205    if (!defined $encodings::encodings->{$encoding}) {
206    print STDERR "unicode::convert2unicode: ERROR: Unsupported encoding ($encoding)\n";
207    return [];
208    }
209
210    my $encodename = "$encoding-unicode";
211    my $enc_info = $encodings::encodings->{$encoding};
212    my $mapfile = &util::filename_cat($ENV{'GSDLHOME'}, "mappings",
213                      "to_uc", $enc_info->{'mapfile'});
214    if (!&loadmapencoding ($encodename, $mapfile)) {
215    print STDERR "unicode: ERROR - could not load encoding $encodename: $! $mapfile\n";
216    return [];
217    }
218   
219    if (defined $enc_info->{'converter'}) {
220    my $converter = $enc_info->{'converter'};
221    return &$converter ($encodename, $textref);
222    }
223
224    if ($unicode::translations{$encodename}->{'count'} == 1) {
225    return &singlebyte2unicode ($encodename, $textref);
226    } else {
227    return &doublebyte2unicode ($encodename, $textref);
228    }
229}
230
231# singlebyte2unicode converts simple 8 bit encodings where characters below
232# 0x80 are normal ascii characters and the rest are decoded using the
233# appropriate mapping files.
234#
235# Examples of encodings that may be converted using singlebyte2unicode are
236# the iso-8859 and windows-125* series.
237sub singlebyte2unicode {
238    my ($encodename, $textref) = @_;
239
240    my @outtext = ();
241    my $len = length($$textref);
242    my ($c);
243    my $i = 0;
244
245    while ($i < $len) {
246    if (($c = ord(substr($$textref, $i, 1))) < 0x80) {
247        # normal ascii character
248        push (@outtext, $c);
249    } else {
250        $c = &transchar ($encodename, $c);
251        # put a black square if cannot translate
252        $c = 0x25A1 if $c == 0;
253        push (@outtext, $c);
254    }
255    $i ++;
256    }
257    return \@outtext;
258}
259
260# doublebyte2unicode converts simple two byte encodings where characters
261# below code point 0x80 are single-byte characters and the rest are
262# double-byte characters.
263#
264# Examples of encodings that may be converted using doublebyte2unicode are
265# CJK encodings like GB encoded Chinese and UHC Korean.
266#
267# Note that no error checking is performed to make sure that the input text
268# is valid for the given encoding.
269#
270# Also, encodings that may contain characters of more than two bytes are
271# not supported (any EUC encoded text may in theory contain 3-byte
272# characters but in practice only one and two byte characters are used).
273sub doublebyte2unicode {
274    my ($encodename, $textref) = @_;   
275   
276    my @outtext = ();
277    my $len = length($$textref);
278    my ($c1, $c2);
279    my $i = 0;
280
281    while ($i < $len) {
282    if (($c1 = ord(substr($$textref, $i, 1))) >= 0x80) {
283        if ($i+1 < $len) {
284        # double-byte character
285        $c2 = ord(substr($$textref, $i+1, 1));
286        my $c = &transchar ($encodename, ($c1 << 8) | $c2);
287        # put a black square if cannot translate
288        $c = 0x25A1 if $c == 0;
289        push (@outtext, $c);
290        $i += 2;
291       
292        } else {
293        # error
294        print STDERR "unicode: ERROR missing second half of double-byte character\n";
295        $i++;
296        }
297       
298    } else {
299        # single-byte character
300        push (@outtext, $c1);
301        $i++;
302    }
303    }
304    return \@outtext;
305}
306
307# Shift-JIS to unicode
308# We can't use doublebyte2unicode for Shift-JIS because it uses some
309# single-byte characters above code point 0x80 (i.e. half-width katakana
310# characters in the range 0xA1-0xDF)
311sub shiftjis2unicode {
312    my ($encodename, $textref) = @_;
313   
314    my @outtext = ();
315    my $len = length($$textref);
316    my ($c1, $c2);
317    my $i = 0;
318
319    while ($i < $len) {
320    $c1 = ord(substr($$textref, $i, 1));
321
322    if (($c1 >= 0xA1 && $c1 <= 0xDF) || $c1 == 0x5c || $c1 == 0x7E) {
323        # Single-byte half-width katakana character or
324        # JIS Roman yen or overline characters
325        my $c = &transchar ($encodename, $c1);
326        # - put a black square if cannot translate
327        $c = 0x25A1 if $c == 0;
328        push (@outtext, $c);
329        $i++;
330
331    } elsif ($c1 < 0x80) {
332        # ASCII
333        push (@outtext, $c1);
334        $i ++;
335
336    } elsif ($c1 < 0xEF) {
337        if ($i+1 < $len) {
338        $c2 = ord(substr($$textref, $i+1, 1));
339        if (($c2 >= 0x40 && $c2 <= 0x7E) || ($c2 >= 0x80 && $c2 <= 0xFC)) {
340            # Double-byte shift-jis character
341            my $c = &transchar ($encodename, ($c1 << 8) | $c2);
342            # put a black square if cannot translate
343            $c = 0x25A1 if $c == 0;
344            push (@outtext, $c);
345        } else {
346            # error
347            print STDERR "unicode: ERROR Invalid Shift-JIS character\n";
348        }
349        $i += 2;
350        } else {
351        # error
352        print STDERR "unicode: ERROR missing second half of Shift-JIS character\n";
353        $i ++;
354        }
355    } else {
356        # error
357        print STDERR "unicode: ERROR Invalid Shift-JIS character\n";
358        $i ++;
359    }
360    }
361    return \@outtext;
362}
363
364sub transchar {
365    my ($encoding, $from) = @_;
366    my $high = ($from / 256) % 256;
367    my $low = $from % 256;
368
369    return 0 unless defined $unicode::translations{$encoding};
370
371    my $block = $unicode::translations{$encoding}->{'map'};
372
373    if (ref ($block->[$high]) ne "ARRAY") {
374    return 0;
375    }
376    return $block->[$high]->[$low];
377}
378
379# %translations is of the form:
380#
381# encodings{encodingname-encodingname}->{'map'}->blocktranslation
382# blocktranslation->[[0-255],[256-511], ..., [65280-65535]]
383#
384# Any of the top translation blocks can point to an undefined
385# value. This data structure aims to allow fast translation and
386# efficient storage.
387%unicode::translations = ();
388
389# @array256 is used for initialisation, there must be
390# a better way...
391# What about this?: @array256 = (0) x 256;
392@unicode::array256 = (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
393         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
394         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
395         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
396         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
397         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
398         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
399         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
400         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
401         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
402         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
403         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
404         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
405         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
406         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
407         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0);
408
409# returns 1 if successful, 0 if unsuccessful
410sub loadmapencoding {
411    my ($encoding, $mapfile) = @_;
412   
413    # check to see if the encoding has already been loaded
414    return 1 if (defined $unicode::translations{$encoding});
415
416    if (! -r $mapfile || -d $mapfile) {
417    return 0;
418    }
419    return 0 unless open (MAPFILE, $mapfile);
420    binmode (MAPFILE);
421
422    $unicode::translations{$encoding} = {'map' => [@unicode::array256], 'count' => 0};
423    my $block = $unicode::translations{$encoding};
424
425    my ($in,$i,$j);
426    while (1) {
427    my $ret=read(MAPFILE, $in, 1);
428    if (!defined($ret)) { # error
429        print STDERR "unicode.pm: error reading mapfile: $!\n";
430        last;
431    }
432    if ($ret != 1) { last }
433    $i = unpack ("C", $in);
434    $block->{'map'}->[$i] = [@unicode::array256];
435    for ($j=0; $j<256 && read(MAPFILE, $in, 2)==2; $j++) {
436        my ($n1, $n2) = unpack ("CC", $in);
437        $block->{'map'}->[$i]->[$j] = ($n1*256) + $n2;
438    }
439    $block->{'count'} ++;
440    }
441
442    close (MAPFILE);
443}
444
445# unicode2singlebyte converts unicode to simple 8 bit encodings where
446# characters below 0x80 are normal ascii characters and the rest are encoded
447# using the appropriate mapping files.
448#
449# Examples of encodings that may be converted using unicode2singlebyte are
450# the iso-8859 and windows-125* series, KOI8-R (Russian), and the Kazakh encoding.
451sub unicode2singlebyte {
452    my ($uniref, $encoding) = @_;
453
454    my $outtext = "";
455    my $encodename = "unicode-$encoding";
456
457    if (!exists $encodings::encodings->{$encoding}) {
458    print STDERR "unicode.pm: ERROR - unsupported encoding "
459        . "'$encoding' requested\n";
460    return "";
461    }
462
463    my $enc_info = $encodings::encodings->{$encoding};
464    my $mapfile = &util::filename_cat($ENV{'GSDLHOME'}, "mappings",
465                      "from_uc", $enc_info->{'mapfile'});
466    if (!&loadmapencoding ($encodename, $mapfile)) {
467    print STDERR "unicode: ERROR - could not load encoding $encodename: $! $mapfile\n";
468    return "";
469    }
470   
471    foreach my $c (@$uniref) {
472    if ($c < 0x80) {
473        # normal ascii character
474        $outtext .= chr($c);
475    } else {
476        # extended ascii character
477        $c = &transchar ($encodename, $c);
478
479        # put a question mark if cannot translate
480        if ($c == 0) {
481        $outtext .= "?";
482        } else {
483        $outtext .= chr($c);
484        }
485    }
486    }
487    return $outtext;
488}
489
490
491# this makes sure that the referenced input string is utf8 encoded, and
492# will change/remove bytes that aren't.
493# returns 0 if the text was already utf8, or 1 if text modified to become utf8
494sub ensure_utf8 {
495    my $stringref=shift;
496
497    if (!defined($stringref) || ref($stringref) ne 'SCALAR') {
498    return $stringref;
499    }
500
501    my $value=$$stringref;
502
503    my $non_utf8_found = 0;
504    $value =~ m/^/g; # to set \G
505    while ($value =~ m!\G.*?([\x80-\xff]+)!sg) {
506    my $highbytes=$1;
507    my $highbyteslength=length($highbytes);
508    # make sure this block of high bytes is utf-8
509    $highbytes =~ /^/g; # set pos()
510    my $byte_replaced = 0;
511    while ($highbytes =~
512        m!\G (?: [\xc0-\xdf][\x80-\xbf]   | # 2 byte utf-8
513            [\xe0-\xef][\x80-\xbf]{2} | # 3 byte
514            [\xf0-\xf7][\x80-\xbf]{3} | # 4 byte
515            [\xf8-\xfb][\x80-\xbf]{4} | # 5 byte
516            [\xfc-\xfd][\x80-\xbf]{5} | # 6 byte
517            )*([\x80-\xff])? !xg
518        ) {
519        # this highbyte is "out-of-place" for valid utf-8
520        my $badbyte=$1;
521        if (!defined $badbyte) {next} # hit end of string
522        my $pos=pos($highbytes);
523        # replace bad byte. assume iso-8859-1 -> utf-8
524        # ascii2utf8 does "extended ascii"... ie iso-8859-1
525        my $replacement=&unicode::ascii2utf8(\$badbyte);
526        substr($highbytes, $pos-1, 1, $replacement);
527        # update the position to continue searching (for \G)
528        pos($highbytes) = $pos+length($replacement)-1;
529        $byte_replaced = 1;
530    }
531    if ($byte_replaced) {
532        # replace this block of high bytes in the $value
533        $non_utf8_found = 1;
534        my $replength=length($highbytes); # we've changed the length
535        my $textpos=pos($value); # pos at end of last match
536        # replace bad bytes with good bytes
537        substr($value, $textpos-$highbyteslength,
538                $highbyteslength, $highbytes);
539        # update the position to continue searching (for \G)
540        pos($value)=$textpos+($replength-$highbyteslength)+1;
541    }
542    }
543
544    $$stringref = $value;
545    return $non_utf8_found;
546}
547
548# Returns true (1) if the given string is utf8 and false (0) if it isn't.
549# Does not modify the string parameter.
550sub check_is_utf8 {
551    my $value=shift;
552
553    if (!defined($value)) {
554    return 0; # not utf8 because it is undefined
555    }
556
557    $value =~ m/^/g; # to set \G
558    while ($value =~ m!\G.*?([\x80-\xff]+)!sg) {
559    my $highbytes=$1;
560    # make sure this block of high bytes is utf-8
561    $highbytes =~ /^/g; # set pos()
562    while ($highbytes =~
563        m!\G (?: [\xc0-\xdf][\x80-\xbf]   | # 2 byte utf-8
564            [\xe0-\xef][\x80-\xbf]{2} | # 3 byte
565            [\xf0-\xf7][\x80-\xbf]{3} | # 4 byte
566            [\xf8-\xfb][\x80-\xbf]{4} | # 5 byte
567            [\xfc-\xfd][\x80-\xbf]{5} | # 6 byte
568            )*([\x80-\xff])? !xg
569        ) {
570        my $badbyte=$1;
571        if (defined $badbyte) { # not end of string
572        return 0; # non-utf8 found
573        }
574    }
575    }
576   
577    return 1;
578}
579
580sub url_encode {
581    my ($text) = @_;
582   
583    if (!&is_url_encoded($text)) {
584    $text =~ s/([^A-Z0-9\ \.\-\_])/sprintf("%%%02X", ord($1))/iseg;
585    }
586    return $text;
587}
588
589sub url_decode {
590    my ($text) = @_;
591
592    $text =~ s/\%([A-F0-9]{2})/pack('C', hex($1))/ige;
593    return $text;
594}
595
596sub is_url_encoded {
597    my ($text) = @_;
598    return ($text =~ m/\%([A-F0-9]{2})/);
599}
600
601# When a filename on the filesystem is already URL-encoded, the
602# URL to it will have %25s in place of every % sign, so that
603# URLs in html pages can refer to the URL-encoded filename.
604# This method changes the URL reference back into the actual
605# (URL-encoded) filename on the filesystem by replacing %25 with %.
606sub url_to_filename {
607    my ($text) =@_;
608    $text =~ s/%25/%/g if is_url_encoded($text);
609    return $text;
610}
611
612# When a filename on the filesystem is already URL-encoded, the
613# URL to it will have %25s in in place of every % sign, so that
614# URLs in html pages can refer to the URL-encoded filename.
615# Given a (URL-encoded) filename on the filesystem, this subroutine
616# returns the URL reference string for it by replacing % with %25.
617# The output string will be the same as the input string if the input
618# already contains one or more %25s. This is to prevent processing
619# a url more than once this way.
620sub filename_to_url {
621    my ($text, $rename_method) = @_;
622   
623    if(!defined $rename_method || $rename_method eq "url") {
624    if($text !~ m/%25/) {
625        $text =~ s/%/%25/g;
626    }
627    }
628    return $text;
629}
630
631
632sub substr
633{
634    my ($utf8_string, $offset, $length) = @_;
635
636    my @unicode_string = @{&utf82unicode($utf8_string)};
637    my $unicode_string_length = scalar(@unicode_string);
638
639    my $substr_start = $offset;
640    if ($substr_start >= $unicode_string_length) {
641    return "";
642    }
643
644    my $substr_end = $offset + $length - 1;
645    if ($substr_end >= $unicode_string_length) {
646    $substr_end = $unicode_string_length - 1;
647    }
648
649    my @unicode_substring = @unicode_string[$substr_start..$substr_end];
650    return &unicode2utf8(\@unicode_substring);
651}
652
653
6541;
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