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[perl5.git] / lib / utf8.pm
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1package utf8;
2
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3$utf8::hint_bits = 0x00800000;
4
e522ce32 5our $VERSION = '1.06';
b75c8c73 6
a0ed51b3 7sub import {
d5448623 8 $^H |= $utf8::hint_bits;
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9 $enc{caller()} = $_[1] if $_[1];
10}
11
12sub unimport {
d5448623 13 $^H &= ~$utf8::hint_bits;
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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");
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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
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29
30=head1 SYNOPSIS
31
32 use utf8;
33 no utf8;
34
2c9359a2 35 # Convert a Perl scalar to/from UTF-8.
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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.
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40 utf8::encode($string);
41 utf8::decode($string);
42
786c9463 43 $flag = utf8::is_utf8(STRING); # since Perl 5.8.1
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44 $flag = utf8::valid(STRING);
45
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46=head1 DESCRIPTION
47
393fec97 48The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
b3419ed8 49program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based
70122e76 50platforms). The C<no utf8> pragma tells Perl to switch back to treating
b3419ed8 51the source text as literal bytes in the current lexical scope.
a0ed51b3 52
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53B<Do not use this pragma for anything else than telling Perl that your
54script is written in UTF-8.> The utility functions described below are
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55directly usable without C<use utf8;>.
56
57Because it is not possible to reliably tell UTF-8 from native 8 bit
58encodings, you need either a Byte Order Mark at the beginning of your
59source code, or C<use utf8;>, to instruct perl.
19b49582 60
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61When UTF-8 becomes the standard source format, this pragma will
62effectively become a no-op. For convenience in what follows the term
63I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based
64platforms and UTF-EBCDIC on EBCDIC based platforms.
a0ed51b3 65
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66See also the effects of the C<-C> switch and its cousin, the
67C<$ENV{PERL_UNICODE}>, in L<perlrun>.
68
ad0029c4 69Enabling the C<utf8> pragma has the following effect:
a0ed51b3 70
4ac9195f 71=over 4
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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
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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
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83=back
84
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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
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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
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92=head2 Utility functions
93
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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.
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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>.
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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).
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109
110B<Note that this function does not handle arbitrary encodings.>
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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
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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<$string> already encoded as native 8 bit does no harm. Can be used to
119make sure that the UTF-8 flag is off, e.g. when you want to make sure
120that the substr() or length() function works with the usually faster
121byte algorithm.
78ea37eb 122
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123Fails if the original I<UTF-X> sequence cannot be represented in the
124native 8 bit encoding. On failure dies or, if the value of C<FAIL_OK> is
125true, returns false.
78ea37eb 126
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127Returns true on success.
128
129B<Note that this function does not handle arbitrary encodings.>
130Therefore Encode is recommended for the general purposes; see also
131L<Encode>.
78ea37eb 132
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133B<NOTE:> this function is experimental and may change or be removed
134without notice.
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135
136=item * utf8::encode($string)
137
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138Converts in-place the character sequence to the corresponding octet
139sequence in I<UTF-X>. The UTF8 flag is turned off, so that after this
140operation, the string is a byte string. Returns nothing.
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141
142B<Note that this function does not handle arbitrary encodings.>
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143Therefore Encode is recommended for the general purposes; see also
144L<Encode>.
094ce63c 145
2575c402 146=item * $success = utf8::decode($string)
1b026014 147
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148Attempts to convert in-place the octet sequence in I<UTF-X> to the
149corresponding character sequence. The UTF-8 flag is turned on only if
150the source string contains multiple-byte I<UTF-X> characters. If
151I<$string> is invalid as I<UTF-X>, returns false; otherwise returns
152true.
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153
154B<Note that this function does not handle arbitrary encodings.>
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155Therefore Encode is recommended for the general purposes; see also
156L<Encode>.
78ea37eb 157
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158B<NOTE:> this function is experimental and may change or be removed
159without notice.
1b026014 160
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161=item * $flag = utf8::is_utf8(STRING)
162
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163(Since Perl 5.8.1) Test whether STRING is in UTF-8 internally.
164Functionally the same as Encode::is_utf8().
8800c35a 165
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166=item * $flag = utf8::valid(STRING)
167
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168[INTERNAL] Test whether STRING is in a consistent state regarding
169UTF-8. Will return true is well-formed UTF-8 and has the UTF-8 flag
170on B<or> if string is held as bytes (both these states are 'consistent').
171Main reason for this routine is to allow Perl's testsuite to check
172that operations have left strings in a consistent state. You most
173probably want to use utf8::is_utf8() instead.
70122e76 174
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175=back
176
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177C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is
178cleared. See L<perlunicode> for more on the UTF8 flag and the C API
179functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>,
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180and C<sv_utf8_decode>, which are wrapped by the Perl functions
181C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
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182C<utf8::decode>. Note that in the Perl 5.8.0 and 5.8.1 implementation
183the functions utf8::is_utf8, utf8::valid, utf8::encode, utf8::decode,
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184utf8::upgrade, and utf8::downgrade are always available, without a
185C<require utf8> statement-- this may change in future releases.
f1e62f77 186
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187=head1 BUGS
188
189One can have Unicode in identifier names, but not in package/class or
190subroutine names. While some limited functionality towards this does
191exist as of Perl 5.8.0, that is more accidental than designed; use of
192Unicode for the said purposes is unsupported.
193
194One reason of this unfinishedness is its (currently) inherent
195unportability: since both package names and subroutine names may need
196to be mapped to file and directory names, the Unicode capability of
197the filesystem becomes important-- and there unfortunately aren't
198portable answers.
199
393fec97 200=head1 SEE ALSO
a0ed51b3 201
2575c402 202L<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode>
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203
204=cut