1package utf8; 2 3$utf8::hint_bits = 0x00800000; 4 5our $VERSION = '1.07'; 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 $flag = utf8::valid(STRING); 45 46=head1 DESCRIPTION 47 48The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the 49program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based 50platforms). The C<no utf8> pragma tells Perl to switch back to treating 51the source text as literal bytes in the current lexical scope. 52 53B<Do not use this pragma for anything else than telling Perl that your 54script is written in UTF-8.> The utility functions described below are 55directly usable without C<use utf8;>. 56 57Because it is not possible to reliably tell UTF-8 from native 8 bit 58encodings, you need either a Byte Order Mark at the beginning of your 59source code, or C<use utf8;>, to instruct perl. 60 61When UTF-8 becomes the standard source format, this pragma will 62effectively become a no-op. For convenience in what follows the term 63I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based 64platforms and UTF-EBCDIC on EBCDIC based platforms. 65 66See also the effects of the C<-C> switch and its cousin, the 67C<$ENV{PERL_UNICODE}>, in L<perlrun>. 68 69Enabling the C<utf8> pragma has the following effect: 70 71=over 4 72 73=item * 74 75Bytes in the source text that have their high-bit set will be treated 76as being part of a literal UTF-X sequence. This includes most 77literals such as identifier names, string constants, and constant 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. 82 83=back 84 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 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;>. 91 92=head2 Utility functions 93 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 96you should not say that unless you really want to have UTF-8 source code. 97 98=over 4 99 100=item * $num_octets = utf8::upgrade($string) 101 102Converts in-place the internal octet sequence in the native encoding 103(Latin-1 or EBCDIC) to the equivalent character sequence in I<UTF-X>. 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). 109 110B<Note that this function does not handle arbitrary encodings.> 111Therefore Encode is recommended for the general purposes; see also 112L<Encode>. 113 114=item * $success = utf8::downgrade($string[, FAIL_OK]) 115 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<$string> already encoded as native 8 bit does no harm. Can be used to 119make sure that the UTF-8 flag is off, e.g. when you want to make sure 120that the substr() or length() function works with the usually faster 121byte algorithm. 122 123Fails if the original I<UTF-X> sequence cannot be represented in the 124native 8 bit encoding. On failure dies or, if the value of C<FAIL_OK> is 125true, returns false. 126 127Returns true on success. 128 129B<Note that this function does not handle arbitrary encodings.> 130Therefore Encode is recommended for the general purposes; see also 131L<Encode>. 132 133=item * utf8::encode($string) 134 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. 138 139B<Note that this function does not handle arbitrary encodings.> 140Therefore Encode is recommended for the general purposes; see also 141L<Encode>. 142 143=item * $success = utf8::decode($string) 144 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. 150 151B<Note that this function does not handle arbitrary encodings.> 152Therefore Encode is recommended for the general purposes; see also 153L<Encode>. 154 155=item * $flag = utf8::is_utf8(STRING) 156 157(Since Perl 5.8.1) Test whether STRING is in UTF-8 internally. 158Functionally the same as Encode::is_utf8(). 159 160=item * $flag = utf8::valid(STRING) 161 162[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. 168 169=back 170 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>, 174and C<sv_utf8_decode>, which are wrapped by the Perl functions 175C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and 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. 180 181=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. 193 194=head1 SEE ALSO 195 196L<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode> 197 198=cut 199