root/gsdl/trunk/perllib/unicode.pm @ 16900

Revision 16900, 16.4 KB (checked in by ak19, 11 years ago)

1. URL_encode method now only encodes urls if they are not already encoded (prevents double encoding). 2. new subroutine is_url_encoded returns true if the given string is already url_encoded

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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
39# ascii2unicode takes an (extended) ascii string (ISO-8859-1)
40# and returns a unicode array.
41sub ascii2unicode {
42    my ($in) = @_;
43    my $out = [];
44
45    my $i = 0;
46    my $len = length($in);
47    while ($i < $len) {
48    push (@$out, ord(substr ($in, $i, 1)));
49    $i++;
50    }
51
52    return $out;
53}
54
55# ascii2utf8 takes a reference to an (extended) ascii string and returns a
56# UTF-8 encoded string. This is just a faster version of
57# "&unicode2utf8(&ascii2unicode($str));"
58# "Extended ascii" really means "iso_8859_1"
59sub ascii2utf8 {
60    my ($in) = @_;
61    my $out = "";
62
63    if (!defined($in)|| !defined($$in)) {
64    return $out;
65    }
66
67    my ($c);
68    my $i = 0;
69    my $len = length($$in);
70    while ($i < $len) {
71    $c = ord (substr ($$in, $i, 1));
72    if ($c < 0x80) {
73        # ascii character
74        $out .= chr ($c);
75
76    } else {
77        # extended ascii character
78        $out .= chr (0xc0 + (($c >> 6) & 0x1f));
79        $out .= chr (0x80 + ($c & 0x3f));
80    }
81    $i++;
82    }
83
84    return $out;
85}
86
87# unicode2utf8 takes a unicode array as input and encodes it
88# using utf-8
89sub unicode2utf8 {
90    my ($in) = @_;
91    my $out = "";
92   
93    foreach my $num (@$in) {
94    next unless defined $num;
95    if ($num < 0x80) {
96        $out .= chr ($num);
97
98    } elsif ($num < 0x800) {
99        $out .= chr (0xc0 + (($num >> 6) & 0x1f));
100        $out .= chr (0x80 + ($num & 0x3f));
101
102    } elsif ($num < 0xFFFF) {
103        $out .= chr (0xe0 + (($num >> 12) & 0xf));
104        $out .= chr (0x80 + (($num >> 6) & 0x3f));
105        $out .= chr (0x80 + ($num & 0x3f));
106
107    } else {
108        # error, don't encode anything
109        die;
110    }
111    }
112    return $out;
113}
114
115# utf82unicode takes a utf-8 string and produces a unicode
116# array
117sub utf82unicode {
118    my ($in) = @_;
119    my $out = [];
120
121    my $i = 0;
122    my ($c1, $c2, $c3);
123    my $len = length($in);
124    while ($i < $len) {
125    if (($c1 = ord(substr ($in, $i, 1))) < 0x80) {
126        # normal ascii character
127        push (@$out, $c1);
128
129    } elsif ($c1 < 0xc0) {
130        # error, was expecting the first byte of an
131        # encoded character. Do nothing.
132
133    } elsif ($c1 < 0xe0 && $i+1 < $len) {
134        # an encoded character with two bytes
135        $c2 = ord (substr ($in, $i+1, 1));
136        if ($c2 >= 0x80 && $c2 < 0xc0) {
137        # everything looks ok
138        push (@$out, ((($c1 & 0x1f) << 6) +
139              ($c2 & 0x3f)));
140        $i++; # gobbled an extra byte
141        }
142
143    } elsif ($c1 < 0xf0 && $i+2 < $len) {
144        # an encoded character with three bytes
145        $c2 = ord (substr ($in, $i+1, 1));
146        $c3 = ord (substr ($in, $i+2, 1));
147        if ($c2 >= 0x80 && $c2 < 0xc0 &&
148        $c3 >= 0x80 && $c3 < 0xc0) {
149        # everything looks ok
150        push (@$out, ((($c1 & 0xf) << 12) +
151              (($c2 & 0x3f) << 6) +
152              ($c3 & 0x3f)));
153
154        $i += 2; # gobbled an extra two bytes
155        }
156
157    } else {
158        # error, only decode Unicode characters not full UCS.
159        # Do nothing.
160    }
161
162    $i++;
163    }
164
165    return $out;
166}
167
168# unicode2ucs2 takes a unicode array and produces a UCS-2
169# unicode string (every two bytes forms a unicode character)
170sub unicode2ucs2 {
171    my ($in) = @_;
172    my $out = "";
173
174    foreach my $num (@$in) {
175    $out .= chr (($num & 0xff00) >> 8);
176    $out .= chr ($num & 0xff);
177    }
178
179    return $out;
180}
181
182# ucs22unicode takes a UCS-2 string and produces a unicode array
183sub ucs22unicode {
184    my ($in) = @_;
185    my $out = [];
186
187    my $i = 0;
188    my $len = length ($in);
189    while ($i+1 < $len) {
190    push (@$out, ord (substr($in, $i, 1)) << 8 +
191          ord (substr($in, $i+1, 1)));
192
193    $i ++;
194    }
195
196    return $out;
197}
198
199# takes a reference to a string and returns a reference to a unicode array
200sub convert2unicode {
201    my ($encoding, $textref) = @_;
202
203    if (!defined $encodings::encodings->{$encoding}) {
204    print STDERR "unicode::convert2unicode: ERROR: Unsupported encoding ($encoding)\n";
205    return [];
206    }
207
208    my $encodename = "$encoding-unicode";
209    my $enc_info = $encodings::encodings->{$encoding};
210    my $mapfile = &util::filename_cat($ENV{'GSDLHOME'}, "mappings",
211                      "to_uc", $enc_info->{'mapfile'});
212    if (!&loadmapencoding ($encodename, $mapfile)) {
213    print STDERR "unicode: ERROR - could not load encoding $encodename: $! $mapfile\n";
214    return [];
215    }
216   
217    if (defined $enc_info->{'converter'}) {
218    my $converter = $enc_info->{'converter'};
219    return &$converter ($encodename, $textref);
220    }
221
222    if ($unicode::translations{$encodename}->{'count'} == 1) {
223    return &singlebyte2unicode ($encodename, $textref);
224    } else {
225    return &doublebyte2unicode ($encodename, $textref);
226    }
227}
228
229# singlebyte2unicode converts simple 8 bit encodings where characters below
230# 0x80 are normal ascii characters and the rest are decoded using the
231# appropriate mapping files.
232#
233# Examples of encodings that may be converted using singlebyte2unicode are
234# the iso-8859 and windows-125* series.
235sub singlebyte2unicode {
236    my ($encodename, $textref) = @_;
237
238    my @outtext = ();
239    my $len = length($$textref);
240    my ($c);
241    my $i = 0;
242
243    while ($i < $len) {
244    if (($c = ord(substr($$textref, $i, 1))) < 0x80) {
245        # normal ascii character
246        push (@outtext, $c);
247    } else {
248        $c = &transchar ($encodename, $c);
249        # put a black square if cannot translate
250        $c = 0x25A1 if $c == 0;
251        push (@outtext, $c);
252    }
253    $i ++;
254    }
255    return \@outtext;
256}
257
258# doublebyte2unicode converts simple two byte encodings where characters
259# below code point 0x80 are single-byte characters and the rest are
260# double-byte characters.
261#
262# Examples of encodings that may be converted using doublebyte2unicode are
263# CJK encodings like GB encoded Chinese and UHC Korean.
264#
265# Note that no error checking is performed to make sure that the input text
266# is valid for the given encoding.
267#
268# Also, encodings that may contain characters of more than two bytes are
269# not supported (any EUC encoded text may in theory contain 3-byte
270# characters but in practice only one and two byte characters are used).
271sub doublebyte2unicode {
272    my ($encodename, $textref) = @_;   
273   
274    my @outtext = ();
275    my $len = length($$textref);
276    my ($c1, $c2);
277    my $i = 0;
278
279    while ($i < $len) {
280    if (($c1 = ord(substr($$textref, $i, 1))) >= 0x80) {
281        if ($i+1 < $len) {
282        # double-byte character
283        $c2 = ord(substr($$textref, $i+1, 1));
284        my $c = &transchar ($encodename, ($c1 << 8) | $c2);
285        # put a black square if cannot translate
286        $c = 0x25A1 if $c == 0;
287        push (@outtext, $c);
288        $i += 2;
289       
290        } else {
291        # error
292        print STDERR "unicode: ERROR missing second half of double-byte character\n";
293        $i++;
294        }
295       
296    } else {
297        # single-byte character
298        push (@outtext, $c1);
299        $i++;
300    }
301    }
302    return \@outtext;
303}
304
305# Shift-JIS to unicode
306# We can't use doublebyte2unicode for Shift-JIS because it uses some
307# single-byte characters above code point 0x80 (i.e. half-width katakana
308# characters in the range 0xA1-0xDF)
309sub shiftjis2unicode {
310    my ($encodename, $textref) = @_;
311   
312    my @outtext = ();
313    my $len = length($$textref);
314    my ($c1, $c2);
315    my $i = 0;
316
317    while ($i < $len) {
318    $c1 = ord(substr($$textref, $i, 1));
319
320    if (($c1 >= 0xA1 && $c1 <= 0xDF) || $c1 == 0x5c || $c1 == 0x7E) {
321        # Single-byte half-width katakana character or
322        # JIS Roman yen or overline characters
323        my $c = &transchar ($encodename, $c1);
324        # - put a black square if cannot translate
325        $c = 0x25A1 if $c == 0;
326        push (@outtext, $c);
327        $i++;
328
329    } elsif ($c1 < 0x80) {
330        # ASCII
331        push (@outtext, $c1);
332        $i ++;
333
334    } elsif ($c1 < 0xEF) {
335        if ($i+1 < $len) {
336        $c2 = ord(substr($$textref, $i+1, 1));
337        if (($c2 >= 0x40 && $c2 <= 0x7E) || ($c2 >= 0x80 && $c2 <= 0xFC)) {
338            # Double-byte shift-jis character
339            my $c = &transchar ($encodename, ($c1 << 8) | $c2);
340            # put a black square if cannot translate
341            $c = 0x25A1 if $c == 0;
342            push (@outtext, $c);
343        } else {
344            # error
345            print STDERR "unicode: ERROR Invalid Shift-JIS character\n";
346        }
347        $i += 2;
348        } else {
349        # error
350        print STDERR "unicode: ERROR missing second half of Shift-JIS character\n";
351        $i ++;
352        }
353    } else {
354        # error
355        print STDERR "unicode: ERROR Invalid Shift-JIS character\n";
356        $i ++;
357    }
358    }
359    return \@outtext;
360}
361
362sub transchar {
363    my ($encoding, $from) = @_;
364    my $high = ($from / 256) % 256;
365    my $low = $from % 256;
366
367    return 0 unless defined $unicode::translations{$encoding};
368
369    my $block = $unicode::translations{$encoding}->{'map'};
370
371    if (ref ($block->[$high]) ne "ARRAY") {
372    return 0;
373    }
374    return $block->[$high]->[$low];
375}
376
377# %translations is of the form:
378#
379# encodings{encodingname-encodingname}->{'map'}->blocktranslation
380# blocktranslation->[[0-255],[256-511], ..., [65280-65535]]
381#
382# Any of the top translation blocks can point to an undefined
383# value. This data structure aims to allow fast translation and
384# efficient storage.
385%unicode::translations = ();
386
387# @array256 is used for initialisation, there must be
388# a better way...
389# What about this?: @array256 = (0) x 256;
390@unicode::array256 = (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
391         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
392         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
407# returns 1 if successful, 0 if unsuccessful
408sub loadmapencoding {
409    my ($encoding, $mapfile) = @_;
410   
411    # check to see if the encoding has already been loaded
412    return 1 if (defined $unicode::translations{$encoding});
413
414    if (! -r $mapfile || -d $mapfile) {
415    return 0;
416    }
417    return 0 unless open (MAPFILE, $mapfile);
418    binmode (MAPFILE);
419
420    $unicode::translations{$encoding} = {'map' => [@unicode::array256], 'count' => 0};
421    my $block = $unicode::translations{$encoding};
422
423    my ($in,$i,$j);
424    while (1) {
425    my $ret=read(MAPFILE, $in, 1);
426    if (!defined($ret)) { # error
427        print STDERR "unicode.pm: error reading mapfile: $!\n";
428        last;
429    }
430    if ($ret != 1) { last }
431    $i = unpack ("C", $in);
432    $block->{'map'}->[$i] = [@unicode::array256];
433    for ($j=0; $j<256 && read(MAPFILE, $in, 2)==2; $j++) {
434        my ($n1, $n2) = unpack ("CC", $in);
435        $block->{'map'}->[$i]->[$j] = ($n1*256) + $n2;
436    }
437    $block->{'count'} ++;
438    }
439
440    close (MAPFILE);
441}
442
443# unicode2singlebyte converts unicode to simple 8 bit encodings where
444# characters below 0x80 are normal ascii characters and the rest are encoded
445# using the appropriate mapping files.
446#
447# Examples of encodings that may be converted using unicode2singlebyte are
448# the iso-8859 and windows-125* series, KOI8-R (Russian), and the Kazakh encoding.
449sub unicode2singlebyte {
450    my ($uniref, $encoding) = @_;
451
452    my $outtext = "";
453    my $encodename = "unicode-$encoding";
454
455    if (!exists $encodings::encodings->{$encoding}) {
456    print STDERR "unicode.pm: ERROR - unsupported encoding "
457        . "'$encoding' requested\n";
458    return "";
459    }
460
461    my $enc_info = $encodings::encodings->{$encoding};
462    my $mapfile = &util::filename_cat($ENV{'GSDLHOME'}, "mappings",
463                      "from_uc", $enc_info->{'mapfile'});
464    if (!&loadmapencoding ($encodename, $mapfile)) {
465    print STDERR "unicode: ERROR - could not load encoding $encodename: $! $mapfile\n";
466    return "";
467    }
468   
469    foreach my $c (@$uniref) {
470    if ($c < 0x80) {
471        # normal ascii character
472        $outtext .= chr($c);
473    } else {
474        # extended ascii character
475        $c = &transchar ($encodename, $c);
476
477        # put a question mark if cannot translate
478        if ($c == 0) {
479        $outtext .= "?";
480        } else {
481        $outtext .= chr($c);
482        }
483    }
484    }
485    return $outtext;
486}
487
488
489# this makes sure that the referenced input string is utf8 encoded, and
490# will change/remove bytes that aren't.
491# returns 0 if the text was already utf8, or 1 if text modified to become utf8
492sub ensure_utf8 {
493    my $stringref=shift;
494
495    if (!defined($stringref) || ref($stringref) ne 'SCALAR') {
496    return $stringref;
497    }
498
499    my $value=$$stringref;
500
501    my $non_utf8_found = 0;
502    $value =~ m/^/g; # to set \G
503    while ($value =~ m!\G.*?([\x80-\xff]+)!sg) {
504    my $highbytes=$1;
505    my $highbyteslength=length($highbytes);
506    # make sure this block of high bytes is utf-8
507    $highbytes =~ /^/g; # set pos()
508    my $byte_replaced = 0;
509    while ($highbytes =~
510        m!\G (?: [\xc0-\xdf][\x80-\xbf]   | # 2 byte utf-8
511            [\xe0-\xef][\x80-\xbf]{2} | # 3 byte
512            [\xf0-\xf7][\x80-\xbf]{3} | # 4 byte
513            [\xf8-\xfb][\x80-\xbf]{4} | # 5 byte
514            [\xfc-\xfd][\x80-\xbf]{5} | # 6 byte
515            )*([\x80-\xff])? !xg
516        ) {
517        # this highbyte is "out-of-place" for valid utf-8
518        my $badbyte=$1;
519        if (!defined $badbyte) {next} # hit end of string
520        my $pos=pos($highbytes);
521        # replace bad byte. assume iso-8859-1 -> utf-8
522        # ascii2utf8 does "extended ascii"... ie iso-8859-1
523        my $replacement=&unicode::ascii2utf8(\$badbyte);
524        substr($highbytes, $pos-1, 1, $replacement);
525        # update the position to continue searching (for \G)
526        pos($highbytes) = $pos+length($replacement)-1;
527        $byte_replaced = 1;
528    }
529    if ($byte_replaced) {
530        # replace this block of high bytes in the $value
531        $non_utf8_found = 1;
532        my $replength=length($highbytes); # we've changed the length
533        my $textpos=pos($value); # pos at end of last match
534        # replace bad bytes with good bytes
535        substr($value, $textpos-$highbyteslength,
536                $highbyteslength, $highbytes);
537        # update the position to continue searching (for \G)
538        pos($value)=$textpos+($replength-$highbyteslength)+1;
539    }
540    }
541
542    $$stringref = $value;
543    return $non_utf8_found;
544}
545
546# Returns true (1) if the given string is utf8 and false (0) if it isn't.
547# Does not modify the string parameter.
548sub check_is_utf8 {
549    my $value=shift;
550
551    if (!defined($value)) {
552    return 0; # not utf8 because it is undefined
553    }
554
555    $value =~ m/^/g; # to set \G
556    while ($value =~ m!\G.*?([\x80-\xff]+)!sg) {
557    my $highbytes=$1;
558    # make sure this block of high bytes is utf-8
559    $highbytes =~ /^/g; # set pos()
560    while ($highbytes =~
561        m!\G (?: [\xc0-\xdf][\x80-\xbf]   | # 2 byte utf-8
562            [\xe0-\xef][\x80-\xbf]{2} | # 3 byte
563            [\xf0-\xf7][\x80-\xbf]{3} | # 4 byte
564            [\xf8-\xfb][\x80-\xbf]{4} | # 5 byte
565            [\xfc-\xfd][\x80-\xbf]{5} | # 6 byte
566            )*([\x80-\xff])? !xg
567        ) {
568        my $badbyte=$1;
569        if (defined $badbyte) { # not end of string
570        return 0; # non-utf8 found
571        }
572    }
573    }
574   
575    return 1;
576}
577
578sub url_encode {
579    my ($text) = @_;
580    if (!&is_url_encoded($text)) {
581    print STDERR "*** not percent encoded yet\n";
582    $text =~ s/([^A-Z0-9\.\-\_])/sprintf("%%%02X", ord($1))/iseg;
583    }
584    return $text;
585}
586
587sub url_decode {
588    my ($text) = @_;
589
590    $text =~ s/\%([A-F0-9]{2})/pack('C', hex($1))/ige;
591    return $text;
592}
593
594sub is_url_encoded {
595    my ($text) = @_;
596    return ($text =~ m/\%([A-F0-9]{2})/);
597}
598
599sub substr
600{
601    my ($utf8_string, $offset, $length) = @_;
602
603    my @unicode_string = @{&utf82unicode($utf8_string)};
604    my $unicode_string_length = scalar(@unicode_string);
605
606    my $substr_start = $offset;
607    if ($substr_start >= $unicode_string_length) {
608    return "";
609    }
610
611    my $substr_end = $offset + $length - 1;
612    if ($substr_end >= $unicode_string_length) {
613    $substr_end = $unicode_string_length - 1;
614    }
615
616    my @unicode_substring = @unicode_string[$substr_start..$substr_end];
617    return &unicode2utf8(\@unicode_substring);
618}
619
620
6211;
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