1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
|
package utf8;
$utf8::hint_bits = 0x00800000;
our $VERSION = '1.00';
sub import {
$^H |= $utf8::hint_bits;
$enc{caller()} = $_[1] if $_[1];
}
sub unimport {
$^H &= ~$utf8::hint_bits;
}
sub AUTOLOAD {
require "utf8_heavy.pl";
goto &$AUTOLOAD if defined &$AUTOLOAD;
Carp::croak("Undefined subroutine $AUTOLOAD called");
}
1;
__END__
=head1 NAME
utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code
=head1 SYNOPSIS
use utf8;
no utf8;
=head1 DESCRIPTION
The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based
platforms). The C<no utf8> pragma tells Perl to switch back to treating
the source text as literal bytes in the current lexical scope.
This pragma is primarily a compatibility device. Perl versions
earlier than 5.6 allowed arbitrary bytes in source code, whereas
in future we would like to standardize on the UTF-8 encoding for
source text. Until UTF-8 becomes the default format for source
text, this pragma should be used to recognize UTF-8 in the source.
When UTF-8 becomes the standard source format, this pragma will
effectively become a no-op. For convenience in what follows the
term I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based
platforms and UTF-EBCDIC on EBCDIC based platforms.
Enabling the C<utf8> pragma has the following effect:
=over 4
=item *
Bytes in the source text that have their high-bit set will be treated
as being part of a literal UTF-8 character. This includes most
literals such as identifiers, string constants, constant regular
expression patterns and package names. On EBCDIC platforms characters
in the Latin 1 character set are treated as being part of a literal
UTF-EBCDIC character.
=back
Note that if you have bytes with the eighth bit on in your script
(for example embedded Latin-1 in your string literals), C<use utf8>
will be unhappy since the bytes are most probably not well-formed
UTF-8. If you want to have such bytes and use utf8, you can disable
utf8 until the end the block (or file, if at top level) by C<no utf8;>.
=head2 Utility functions
The following functions are defined in the C<utf8::> package by the perl core.
=over 4
=item * $num_octets = utf8::upgrade($string);
Converts internal representation of string to the Perl's internal
I<UTF-X> form. Returns the number of octets necessary to represent
the string as I<UTF-X>.
=item * utf8::downgrade($string[, CHECK])
Converts internal representation of string to be un-encoded bytes.
=item * utf8::encode($string)
Converts (in-place) I<$string> from logical characters to octet sequence
representing it in Perl's I<UTF-X> encoding.
=item * $flag = utf8::decode($string)
Attempts to convert I<$string> in-place from Perl's I<UTF-X> encoding
into logical characters.
=back
C<utf8::encode> is like C<utf8::upgrade> but the UTF8 flag does not
get turned on. See L<perlunicode> for more on the UTF8 flag and the C
API functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>,
C<sv_utf8_encode>, C<sv_utf8_decode> that are wrapped by the Perl
functions C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
C<utf8::decode>.
=head1 SEE ALSO
L<perlunicode>, L<bytes>
=cut
|
