perl/lib/utf8.pm

package utf8;

$utf8::hint_bits = 0x00800000;

our $VERSION = '1.05';

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;
    require Carp;
    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;

    # Convert a Perl scalar to/from UTF-8.
    $num_octets = utf8::upgrade($string);
    $success    = utf8::downgrade($string[, FAIL_OK]);

    # Change the native bytes of a Perl scalar to/from UTF-8 bytes.
    utf8::encode($string);
    utf8::decode($string);

    $flag = utf8::is_utf8(STRING); # since Perl 5.8.1
    $flag = utf8::valid(STRING);

=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.

B<Do not use this pragma for anything else than telling Perl that your
script is written in UTF-8.> The utility functions described below are
useful for their own purposes, but they are not really part of the
"pragmatic" effect.

Until UTF-8 becomes the default format for source text, either this
pragma or the L</encoding> 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.

See also the effects of the C<-C> switch and its cousin, the
C<$ENV{PERL_UNICODE}>, in L<perlrun>.

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 identifier names, string constants, and constant
regular expression patterns.

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;>.

If you want to automatically upgrade your 8-bit legacy bytes to UTF-8,
use the L</encoding> pragma instead of this pragma.  For example, if
you want to implicitly upgrade your ISO 8859-1 (Latin-1) bytes to UTF-8
as used in e.g. C<chr()> and C<\x{...}>, try this:

    use encoding "latin-1";
    my $c = chr(0xc4);
    my $x = "\x{c5}";

In case you are wondering: yes, C<use encoding 'utf8';> works much
the same as C<use utf8;>.

=head2 Utility functions

The following functions are defined in the C<utf8::> package by the
Perl core.  You do not need to say C<use utf8> to use these and in fact
you should not say that  unless you really want to have UTF-8 source code.

=over 4

=item * $num_octets = utf8::upgrade($string)

Converts in-place the octet sequence in the native encoding
(Latin-1 or EBCDIC) to the equivalent character sequence in I<UTF-X>.
I<$string> already encoded as characters does no harm.
Returns the number of octets necessary to represent the string as I<UTF-X>.
Can be used to make sure that the UTF-8 flag is on,
so that C<\w> or C<lc()> work as Unicode on strings
containing characters in the range 0x80-0xFF (on ASCII and
derivatives).

B<Note that this function does not handle arbitrary encodings.>
Therefore I<Encode.pm> is recommended for the general purposes.

Affected by the encoding pragma.

=item * $success = utf8::downgrade($string[, FAIL_OK])

Converts in-place the character sequence in I<UTF-X>
to the equivalent octet sequence in the native encoding (Latin-1 or EBCDIC).
I<$string> already encoded as octets does no harm.
Returns true on success. On failure dies or, if the value of
C<FAIL_OK> is true, returns false.
Can be used to make sure that the UTF-8 flag is off,
e.g. when you want to make sure that the substr() or length() function
works with the usually faster byte algorithm.

B<Note that this function does not handle arbitrary encodings.>
Therefore I<Encode.pm> is recommended for the general purposes.

B<Not> affected by the encoding pragma.

B<NOTE:> this function is experimental and may change
or be removed without notice.

=item * utf8::encode($string)

Converts in-place the character sequence to the corresponding octet sequence
in I<UTF-X>.  The UTF-8 flag is turned off.  Returns nothing.

B<Note that this function does not handle arbitrary encodings.>
Therefore I<Encode.pm> is recommended for the general purposes.

=item * utf8::decode($string)

Attempts to convert in-place the octet sequence in I<UTF-X>
to the corresponding character sequence.  The UTF-8 flag is turned on
only if the source string contains multiple-byte I<UTF-X> characters.
If I<$string> is invalid as I<UTF-X>, returns false; otherwise returns true.

B<Note that this function does not handle arbitrary encodings.>
Therefore I<Encode.pm> is recommended for the general purposes.

B<NOTE:> this function is experimental and may change
or be removed without notice.

=item * $flag = utf8::is_utf8(STRING)

(Since Perl 5.8.1)  Test whether STRING is in UTF-8.  Functionally
the same as Encode::is_utf8().

=item * $flag = utf8::valid(STRING)

[INTERNAL] Test whether STRING is in a consistent state regarding
UTF-8.  Will return true is well-formed UTF-8 and has the UTF-8 flag
on B<or> if string is held as bytes (both these states are 'consistent').
Main reason for this routine is to allow Perl's testsuite to check
that operations have left strings in a consistent state.  You most
probably want to use utf8::is_utf8() instead.

=back

C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is
cleared.  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>,
and C<sv_utf8_decode>, which are wrapped by the Perl functions
C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
C<utf8::decode>.  Note that in the Perl 5.8.0 and 5.8.1 implementation
the functions utf8::is_utf8, utf8::valid, utf8::encode, utf8::decode,
utf8::upgrade, and utf8::downgrade are always available, without a
C<require utf8> statement-- this may change in future releases.

=head1 BUGS

One can have Unicode in identifier names, but not in package/class or
subroutine names.  While some limited functionality towards this does
exist as of Perl 5.8.0, that is more accidental than designed; use of
Unicode for the said purposes is unsupported.

One reason of this unfinishedness is its (currently) inherent
unportability: since both package names and subroutine names may need
to be mapped to file and directory names, the Unicode capability of
the filesystem becomes important-- and there unfortunately aren't
portable answers.

=head1 SEE ALSO

L<perluniintro>, L<encoding>, L<perlrun>, L<bytes>, L<perlunicode>

=cut
Revision:	1.1
Committed:	Thu Jun 30 14:27:09 2005 UTC (21 years, 3 months ago) by root
Branch:	MAIN
CVS Tags:	PERL-5-8-7, HEAD
Branch point for:	PERL
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	package utf8;
2
3			$utf8::hint_bits = 0x00800000;
4
5			our $VERSION = '1.05';
6
7			sub import {
8			$^H \|= $utf8::hint_bits;
9			$enc{caller()} = $_[1] if $_[1];
10			}
11
12			sub unimport {
13			$^H &= ~$utf8::hint_bits;
14			}
15
16			sub AUTOLOAD {
17			require "utf8_heavy.pl";
18			goto &$AUTOLOAD if defined &$AUTOLOAD;
19			require Carp;
20			Carp::croak("Undefined subroutine $AUTOLOAD called");
21			}
22
23			1;
24			__END__
25
26			=head1 NAME
27
28			utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code
29
30			=head1 SYNOPSIS
31
32			use utf8;
33			no utf8;
34
35			# Convert a Perl scalar to/from UTF-8.
36			$num_octets = utf8::upgrade($string);
37			$success = utf8::downgrade($string[, FAIL_OK]);
38
39			# Change the native bytes of a Perl scalar to/from UTF-8 bytes.
40			utf8::encode($string);
41			utf8::decode($string);
42
43			$flag = utf8::is_utf8(STRING); # since Perl 5.8.1
44			$flag = utf8::valid(STRING);
45
46			=head1 DESCRIPTION
47
48			The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
49			program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based
50			platforms). The C<no utf8> pragma tells Perl to switch back to treating
51			the source text as literal bytes in the current lexical scope.
52
53			This pragma is primarily a compatibility device. Perl versions
54			earlier than 5.6 allowed arbitrary bytes in source code, whereas
55			in future we would like to standardize on the UTF-8 encoding for
56			source text.
57
58			B<Do not use this pragma for anything else than telling Perl that your
59			script is written in UTF-8.> The utility functions described below are
60			useful for their own purposes, but they are not really part of the
61			"pragmatic" effect.
62
63			Until UTF-8 becomes the default format for source text, either this
64			pragma or the L</encoding> pragma should be used to recognize UTF-8
65			in the source. When UTF-8 becomes the standard source format, this
66			pragma will effectively become a no-op. For convenience in what
67			follows the term I<UTF-X> is used to refer to UTF-8 on ASCII and ISO
68			Latin based platforms and UTF-EBCDIC on EBCDIC based platforms.
69
70			See also the effects of the C<-C> switch and its cousin, the
71			C<$ENV{PERL_UNICODE}>, in L<perlrun>.
72
73			Enabling the C<utf8> pragma has the following effect:
74
75			=over 4
76
77			=item *
78
79			Bytes in the source text that have their high-bit set will be treated
80			as being part of a literal UTF-8 character. This includes most
81			literals such as identifier names, string constants, and constant
82			regular expression patterns.
83
84			On EBCDIC platforms characters in the Latin 1 character set are
85			treated as being part of a literal UTF-EBCDIC character.
86
87			=back
88
89			Note that if you have bytes with the eighth bit on in your script
90			(for example embedded Latin-1 in your string literals), C<use utf8>
91			will be unhappy since the bytes are most probably not well-formed
92			UTF-8. If you want to have such bytes and use utf8, you can disable
93			utf8 until the end the block (or file, if at top level) by C<no utf8;>.
94
95			If you want to automatically upgrade your 8-bit legacy bytes to UTF-8,
96			use the L</encoding> pragma instead of this pragma. For example, if
97			you want to implicitly upgrade your ISO 8859-1 (Latin-1) bytes to UTF-8
98			as used in e.g. C<chr()> and C<\x{...}>, try this:
99
100			use encoding "latin-1";
101			my $c = chr(0xc4);
102			my $x = "\x{c5}";
103
104			In case you are wondering: yes, C<use encoding 'utf8';> works much
105			the same as C<use utf8;>.
106
107			=head2 Utility functions
108
109			The following functions are defined in the C<utf8::> package by the
110			Perl core. You do not need to say C<use utf8> to use these and in fact
111			you should not say that unless you really want to have UTF-8 source code.
112
113			=over 4
114
115			=item * $num_octets = utf8::upgrade($string)
116
117			Converts in-place the octet sequence in the native encoding
118			(Latin-1 or EBCDIC) to the equivalent character sequence in I<UTF-X>.
119			I<$string> already encoded as characters does no harm.
120			Returns the number of octets necessary to represent the string as I<UTF-X>.
121			Can be used to make sure that the UTF-8 flag is on,
122			so that C<\w> or C<lc()> work as Unicode on strings
123			containing characters in the range 0x80-0xFF (on ASCII and
124			derivatives).
125
126			B<Note that this function does not handle arbitrary encodings.>
127			Therefore I<Encode.pm> is recommended for the general purposes.
128
129			Affected by the encoding pragma.
130
131			=item * $success = utf8::downgrade($string[, FAIL_OK])
132
133			Converts in-place the character sequence in I<UTF-X>
134			to the equivalent octet sequence in the native encoding (Latin-1 or EBCDIC).
135			I<$string> already encoded as octets does no harm.
136			Returns true on success. On failure dies or, if the value of
137			C<FAIL_OK> is true, returns false.
138			Can be used to make sure that the UTF-8 flag is off,
139			e.g. when you want to make sure that the substr() or length() function
140			works with the usually faster byte algorithm.
141
142			B<Note that this function does not handle arbitrary encodings.>
143			Therefore I<Encode.pm> is recommended for the general purposes.
144
145			B<Not> affected by the encoding pragma.
146
147			B<NOTE:> this function is experimental and may change
148			or be removed without notice.
149
150			=item * utf8::encode($string)
151
152			Converts in-place the character sequence to the corresponding octet sequence
153			in I<UTF-X>. The UTF-8 flag is turned off. Returns nothing.
154
155			B<Note that this function does not handle arbitrary encodings.>
156			Therefore I<Encode.pm> is recommended for the general purposes.
157
158			=item * utf8::decode($string)
159
160			Attempts to convert in-place the octet sequence in I<UTF-X>
161			to the corresponding character sequence. The UTF-8 flag is turned on
162			only if the source string contains multiple-byte I<UTF-X> characters.
163			If I<$string> is invalid as I<UTF-X>, returns false; otherwise returns true.
164
165			B<Note that this function does not handle arbitrary encodings.>
166			Therefore I<Encode.pm> is recommended for the general purposes.
167
168			B<NOTE:> this function is experimental and may change
169			or be removed without notice.
170
171			=item * $flag = utf8::is_utf8(STRING)
172
173			(Since Perl 5.8.1) Test whether STRING is in UTF-8. Functionally
174			the same as Encode::is_utf8().
175
176			=item * $flag = utf8::valid(STRING)
177
178			[INTERNAL] Test whether STRING is in a consistent state regarding
179			UTF-8. Will return true is well-formed UTF-8 and has the UTF-8 flag
180			on B<or> if string is held as bytes (both these states are 'consistent').
181			Main reason for this routine is to allow Perl's testsuite to check
182			that operations have left strings in a consistent state. You most
183			probably want to use utf8::is_utf8() instead.
184
185			=back
186
187			C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is
188			cleared. See L<perlunicode> for more on the UTF8 flag and the C API
189			functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>,
190			and C<sv_utf8_decode>, which are wrapped by the Perl functions
191			C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
192			C<utf8::decode>. Note that in the Perl 5.8.0 and 5.8.1 implementation
193			the functions utf8::is_utf8, utf8::valid, utf8::encode, utf8::decode,
194			utf8::upgrade, and utf8::downgrade are always available, without a
195			C<require utf8> statement-- this may change in future releases.
196
197			=head1 BUGS
198
199			One can have Unicode in identifier names, but not in package/class or
200			subroutine names. While some limited functionality towards this does
201			exist as of Perl 5.8.0, that is more accidental than designed; use of
202			Unicode for the said purposes is unsupported.
203
204			One reason of this unfinishedness is its (currently) inherent
205			unportability: since both package names and subroutine names may need
206			to be mapped to file and directory names, the Unicode capability of
207			the filesystem becomes important-- and there unfortunately aren't
208			portable answers.
209
210			=head1 SEE ALSO
211
212			L<perluniintro>, L<encoding>, L<perlrun>, L<bytes>, L<perlunicode>
213
214			=cut