This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
deprecate bytes.pm
[perl5.git] / lib / utf8.pm
CommitLineData
a0ed51b3
LW
1package utf8;
2
d5448623
GS
3$utf8::hint_bits = 0x00800000;
4
075d4edd 5our $VERSION = '1.07';
b75c8c73 6
a0ed51b3 7sub import {
d5448623 8 $^H |= $utf8::hint_bits;
a0ed51b3
LW
9 $enc{caller()} = $_[1] if $_[1];
10}
11
12sub unimport {
d5448623 13 $^H &= ~$utf8::hint_bits;
a0ed51b3
LW
14}
15
16sub AUTOLOAD {
17 require "utf8_heavy.pl";
daf4d4ea 18 goto &$AUTOLOAD if defined &$AUTOLOAD;
bd7017d3 19 require Carp;
daf4d4ea 20 Carp::croak("Undefined subroutine $AUTOLOAD called");
a0ed51b3
LW
21}
22
231;
24__END__
25
26=head1 NAME
27
b3419ed8 28utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code
a0ed51b3
LW
29
30=head1 SYNOPSIS
31
32 use utf8;
33 no utf8;
34
2c9359a2 35 # Convert a Perl scalar to/from UTF-8.
973655a8
SB
36 $num_octets = utf8::upgrade($string);
37 $success = utf8::downgrade($string[, FAIL_OK]);
38
2c9359a2 39 # Change the native bytes of a Perl scalar to/from UTF-8 bytes.
973655a8
SB
40 utf8::encode($string);
41 utf8::decode($string);
42
786c9463 43 $flag = utf8::is_utf8(STRING); # since Perl 5.8.1
973655a8
SB
44 $flag = utf8::valid(STRING);
45
a0ed51b3
LW
46=head1 DESCRIPTION
47
393fec97 48The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
b3419ed8 49program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based
70122e76 50platforms). The C<no utf8> pragma tells Perl to switch back to treating
b3419ed8 51the source text as literal bytes in the current lexical scope.
a0ed51b3 52
19b49582
JH
53B<Do not use this pragma for anything else than telling Perl that your
54script is written in UTF-8.> The utility functions described below are
2575c402
JW
55directly usable without C<use utf8;>.
56
57Because it is not possible to reliably tell UTF-8 from native 8 bit
58encodings, you need either a Byte Order Mark at the beginning of your
59source code, or C<use utf8;>, to instruct perl.
19b49582 60
2575c402
JW
61When UTF-8 becomes the standard source format, this pragma will
62effectively become a no-op. For convenience in what follows the term
63I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based
64platforms and UTF-EBCDIC on EBCDIC based platforms.
a0ed51b3 65
a74e8b45
JH
66See also the effects of the C<-C> switch and its cousin, the
67C<$ENV{PERL_UNICODE}>, in L<perlrun>.
68
ad0029c4 69Enabling the C<utf8> pragma has the following effect:
a0ed51b3 70
4ac9195f 71=over 4
a0ed51b3
LW
72
73=item *
74
393fec97 75Bytes in the source text that have their high-bit set will be treated
2fa62f66 76as being part of a literal UTF-X sequence. This includes most
c20e2abd 77literals such as identifier names, string constants, and constant
8f8cf39c
JH
78regular expression patterns.
79
80On EBCDIC platforms characters in the Latin 1 character set are
81treated as being part of a literal UTF-EBCDIC character.
a0ed51b3 82
4ac9195f
MS
83=back
84
ae90e350
JH
85Note that if you have bytes with the eighth bit on in your script
86(for example embedded Latin-1 in your string literals), C<use utf8>
87will be unhappy since the bytes are most probably not well-formed
2fa62f66
AT
88UTF-X. If you want to have such bytes under C<use utf8>, you can disable
89this pragma until the end the block (or file, if at top level) by
90C<no utf8;>.
ae90e350 91
1b026014
NIS
92=head2 Utility functions
93
8800c35a
JH
94The following functions are defined in the C<utf8::> package by the
95Perl core. You do not need to say C<use utf8> to use these and in fact
19b49582 96you should not say that unless you really want to have UTF-8 source code.
1b026014
NIS
97
98=over 4
99
973655a8 100=item * $num_octets = utf8::upgrade($string)
1b026014 101
2575c402 102Converts in-place the internal octet sequence in the native encoding
78ea37eb 103(Latin-1 or EBCDIC) to the equivalent character sequence in I<UTF-X>.
2575c402
JW
104I<$string> already encoded as characters does no harm. Returns the
105number of octets necessary to represent the string as I<UTF-X>. Can be
106used to make sure that the UTF-8 flag is on, so that C<\w> or C<lc()>
107work as Unicode on strings containing characters in the range 0x80-0xFF
108(on ASCII and derivatives).
78ea37eb
ST
109
110B<Note that this function does not handle arbitrary encodings.>
2575c402
JW
111Therefore Encode is recommended for the general purposes; see also
112L<Encode>.
1b026014 113
973655a8 114=item * $success = utf8::downgrade($string[, FAIL_OK])
1b026014 115
2575c402
JW
116Converts in-place the internal octet sequence in I<UTF-X> to the
117equivalent octet sequence in the native encoding (Latin-1 or EBCDIC).
118I<$string> already encoded as native 8 bit does no harm. Can be used to
119make sure that the UTF-8 flag is off, e.g. when you want to make sure
120that the substr() or length() function works with the usually faster
121byte algorithm.
78ea37eb 122
2575c402
JW
123Fails if the original I<UTF-X> sequence cannot be represented in the
124native 8 bit encoding. On failure dies or, if the value of C<FAIL_OK> is
125true, returns false.
78ea37eb 126
2575c402
JW
127Returns true on success.
128
129B<Note that this function does not handle arbitrary encodings.>
130Therefore Encode is recommended for the general purposes; see also
131L<Encode>.
78ea37eb 132
1b026014
NIS
133=item * utf8::encode($string)
134
2575c402
JW
135Converts in-place the character sequence to the corresponding octet
136sequence in I<UTF-X>. The UTF8 flag is turned off, so that after this
137operation, the string is a byte string. Returns nothing.
78ea37eb
ST
138
139B<Note that this function does not handle arbitrary encodings.>
2575c402
JW
140Therefore Encode is recommended for the general purposes; see also
141L<Encode>.
094ce63c 142
2575c402 143=item * $success = utf8::decode($string)
1b026014 144
2575c402
JW
145Attempts to convert in-place the octet sequence in I<UTF-X> to the
146corresponding character sequence. The UTF-8 flag is turned on only if
147the source string contains multiple-byte I<UTF-X> characters. If
148I<$string> is invalid as I<UTF-X>, returns false; otherwise returns
149true.
78ea37eb
ST
150
151B<Note that this function does not handle arbitrary encodings.>
2575c402
JW
152Therefore Encode is recommended for the general purposes; see also
153L<Encode>.
78ea37eb 154
8800c35a
JH
155=item * $flag = utf8::is_utf8(STRING)
156
2575c402
JW
157(Since Perl 5.8.1) Test whether STRING is in UTF-8 internally.
158Functionally the same as Encode::is_utf8().
8800c35a 159
70122e76
JH
160=item * $flag = utf8::valid(STRING)
161
8800c35a
JH
162[INTERNAL] Test whether STRING is in a consistent state regarding
163UTF-8. Will return true is well-formed UTF-8 and has the UTF-8 flag
164on B<or> if string is held as bytes (both these states are 'consistent').
165Main reason for this routine is to allow Perl's testsuite to check
166that operations have left strings in a consistent state. You most
167probably want to use utf8::is_utf8() instead.
70122e76 168
1b026014
NIS
169=back
170
7d865a91
JH
171C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is
172cleared. See L<perlunicode> for more on the UTF8 flag and the C API
173functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>,
094ce63c
AT
174and C<sv_utf8_decode>, which are wrapped by the Perl functions
175C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
7edb8f2b
RGS
176C<utf8::decode>. Also, the functions utf8::is_utf8, utf8::valid,
177utf8::encode, utf8::decode, utf8::upgrade, and utf8::downgrade are
178actually internal, and thus always available, without a C<require utf8>
179statement.
f1e62f77 180
8f8cf39c
JH
181=head1 BUGS
182
183One can have Unicode in identifier names, but not in package/class or
184subroutine names. While some limited functionality towards this does
185exist as of Perl 5.8.0, that is more accidental than designed; use of
186Unicode for the said purposes is unsupported.
187
188One reason of this unfinishedness is its (currently) inherent
189unportability: since both package names and subroutine names may need
190to be mapped to file and directory names, the Unicode capability of
191the filesystem becomes important-- and there unfortunately aren't
192portable answers.
193
393fec97 194=head1 SEE ALSO
a0ed51b3 195
2575c402 196L<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode>
a0ed51b3
LW
197
198=cut