1package utf8;
2
3$utf8::hint_bits = 0x00800000;
4
5our $VERSION = '1.06';
6
7sub import {
8    $^H |= $utf8::hint_bits;
9    $enc{caller()} = $_[1] if $_[1];
10}
11
12sub unimport {
13    $^H &= ~$utf8::hint_bits;
14}
15
16sub AUTOLOAD {
17    require "utf8_heavy.pl";
18    goto &$AUTOLOAD if defined &$AUTOLOAD;
19    require Carp;
20    Carp::croak("Undefined subroutine $AUTOLOAD called");
21}
22
231;
24__END__
25
26=head1 NAME
27
28utf8 - 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    $flag = utf8::valid(STRING);
45
46=head1 DESCRIPTION
47
48The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
49program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based
50platforms).  The C<no utf8> pragma tells Perl to switch back to treating
51the source text as literal bytes in the current lexical scope.
52
53This pragma is primarily a compatibility device.  Perl versions
54earlier than 5.6 allowed arbitrary bytes in source code, whereas
55in future we would like to standardize on the UTF-8 encoding for
56source text.
57
58B<Do not use this pragma for anything else than telling Perl that your
59script is written in UTF-8.> The utility functions described below are
60useful for their own purposes, but they are not really part of the
61"pragmatic" effect.
62
63Until UTF-8 becomes the default format for source text, either this
64pragma or the L<encoding> pragma should be used to recognize UTF-8
65in the source.  When UTF-8 becomes the standard source format, this
66pragma will effectively become a no-op.  For convenience in what
67follows the term I<UTF-X> is used to refer to UTF-8 on ASCII and ISO
68Latin based platforms and UTF-EBCDIC on EBCDIC based platforms.
69
70See also the effects of the C<-C> switch and its cousin, the
71C<$ENV{PERL_UNICODE}>, in L<perlrun>.
72
73Enabling the C<utf8> pragma has the following effect:
74
75=over 4
76
77=item *
78
79Bytes in the source text that have their high-bit set will be treated
80as being part of a literal UTF-8 character.  This includes most
81literals such as identifier names, string constants, and constant
82regular expression patterns.
83
84On EBCDIC platforms characters in the Latin 1 character set are
85treated as being part of a literal UTF-EBCDIC character.
86
87=back
88
89Note 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>
91will be unhappy since the bytes are most probably not well-formed
92UTF-8.  If you want to have such bytes and use utf8, you can disable
93utf8 until the end the block (or file, if at top level) by C<no utf8;>.
94
95If you want to automatically upgrade your 8-bit legacy bytes to UTF-8,
96use the L<encoding> pragma instead of this pragma.  For example, if
97you want to implicitly upgrade your ISO 8859-1 (Latin-1) bytes to UTF-8
98as 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
104In case you are wondering: yes, C<use encoding 'utf8';> works much
105the same as C<use utf8;>.
106
107=head2 Utility functions
108
109The following functions are defined in the C<utf8::> package by the
110Perl core.  You do not need to say C<use utf8> to use these and in fact
111you 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
117Converts in-place the octet sequence in the native encoding
118(Latin-1 or EBCDIC) to the equivalent character sequence in I<UTF-X>.
119I<$string> already encoded as characters does no harm.
120Returns the number of octets necessary to represent the string as I<UTF-X>.
121Can be used to make sure that the UTF-8 flag is on,
122so that C<\w> or C<lc()> work as Unicode on strings
123containing characters in the range 0x80-0xFF (on ASCII and
124derivatives).
125
126B<Note that this function does not handle arbitrary encodings.>
127Therefore I<Encode.pm> is recommended for the general purposes.
128
129Affected by the encoding pragma.
130
131=item * $success = utf8::downgrade($string[, FAIL_OK])
132
133Converts in-place the character sequence in I<UTF-X>
134to the equivalent octet sequence in the native encoding (Latin-1 or EBCDIC).
135I<$string> already encoded as octets does no harm.
136Returns true on success. On failure dies or, if the value of
137C<FAIL_OK> is true, returns false.
138Can be used to make sure that the UTF-8 flag is off,
139e.g. when you want to make sure that the substr() or length() function
140works with the usually faster byte algorithm.
141
142B<Note that this function does not handle arbitrary encodings.>
143Therefore I<Encode.pm> is recommended for the general purposes.
144
145B<Not> affected by the encoding pragma.
146
147B<NOTE:> this function is experimental and may change
148or be removed without notice.
149
150=item * utf8::encode($string)
151
152Converts in-place the character sequence to the corresponding octet sequence
153in I<UTF-X>.  The UTF-8 flag is turned off.  Returns nothing.
154
155B<Note that this function does not handle arbitrary encodings.>
156Therefore I<Encode.pm> is recommended for the general purposes.
157
158=item * utf8::decode($string)
159
160Attempts to convert in-place the octet sequence in I<UTF-X>
161to the corresponding character sequence.  The UTF-8 flag is turned on
162only if the source string contains multiple-byte I<UTF-X> characters.
163If I<$string> is invalid as I<UTF-X>, returns false; otherwise returns true.
164
165B<Note that this function does not handle arbitrary encodings.>
166Therefore I<Encode.pm> is recommended for the general purposes.
167
168B<NOTE:> this function is experimental and may change
169or 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
174the same as Encode::is_utf8().
175
176=item * $flag = utf8::valid(STRING)
177
178[INTERNAL] Test whether STRING is in a consistent state regarding
179UTF-8.  Will return true is well-formed UTF-8 and has the UTF-8 flag
180on B<or> if string is held as bytes (both these states are 'consistent').
181Main reason for this routine is to allow Perl's testsuite to check
182that operations have left strings in a consistent state.  You most
183probably want to use utf8::is_utf8() instead.
184
185=back
186
187C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is
188cleared.  See L<perlunicode> for more on the UTF8 flag and the C API
189functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>,
190and C<sv_utf8_decode>, which are wrapped by the Perl functions
191C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
192C<utf8::decode>.  Note that in the Perl 5.8.0 and 5.8.1 implementation
193the functions utf8::is_utf8, utf8::valid, utf8::encode, utf8::decode,
194utf8::upgrade, and utf8::downgrade are always available, without a
195C<require utf8> statement-- this may change in future releases.
196
197=head1 BUGS
198
199One can have Unicode in identifier names, but not in package/class or
200subroutine names.  While some limited functionality towards this does
201exist as of Perl 5.8.0, that is more accidental than designed; use of
202Unicode for the said purposes is unsupported.
203
204One reason of this unfinishedness is its (currently) inherent
205unportability: since both package names and subroutine names may need
206to be mapped to file and directory names, the Unicode capability of
207the filesystem becomes important-- and there unfortunately aren't
208portable answers.
209
210=head1 SEE ALSO
211
212L<perluniintro>, L<encoding>, L<perlrun>, L<bytes>, L<perlunicode>
213
214=cut
215