1package utf8; 2 3$utf8::hint_bits = 0x00800000; 4 5our $VERSION = '1.08'; 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 the internal representation of a Perl scalar to/from UTF-8. 36 37 $num_octets = utf8::upgrade($string); 38 $success = utf8::downgrade($string[, FAIL_OK]); 39 40 # Change each character of a Perl scalar to/from a series of 41 # characters that represent the UTF-8 bytes of each original character. 42 43 utf8::encode($string); # "\x{100}" becomes "\xc4\x80" 44 utf8::decode($string); # "\xc4\x80" becomes "\x{100}" 45 46 $flag = utf8::is_utf8(STRING); # since Perl 5.8.1 47 $flag = utf8::valid(STRING); 48 49=head1 DESCRIPTION 50 51The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the 52program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based 53platforms). The C<no utf8> pragma tells Perl to switch back to treating 54the source text as literal bytes in the current lexical scope. 55 56B<Do not use this pragma for anything else than telling Perl that your 57script is written in UTF-8.> The utility functions described below are 58directly usable without C<use utf8;>. 59 60Because it is not possible to reliably tell UTF-8 from native 8 bit 61encodings, you need either a Byte Order Mark at the beginning of your 62source code, or C<use utf8;>, to instruct perl. 63 64When UTF-8 becomes the standard source format, this pragma will 65effectively become a no-op. For convenience in what follows the term 66I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based 67platforms and UTF-EBCDIC on EBCDIC based platforms. 68 69See also the effects of the C<-C> switch and its cousin, the 70C<$ENV{PERL_UNICODE}>, in L<perlrun>. 71 72Enabling the C<utf8> pragma has the following effect: 73 74=over 4 75 76=item * 77 78Bytes in the source text that have their high-bit set will be treated 79as being part of a literal UTF-X sequence. This includes most 80literals such as identifier names, string constants, and constant 81regular expression patterns. 82 83On EBCDIC platforms characters in the Latin 1 character set are 84treated as being part of a literal UTF-EBCDIC character. 85 86=back 87 88Note that if you have bytes with the eighth bit on in your script 89(for example embedded Latin-1 in your string literals), C<use utf8> 90will be unhappy since the bytes are most probably not well-formed 91UTF-X. If you want to have such bytes under C<use utf8>, you can disable 92this pragma until the end the block (or file, if at top level) by 93C<no utf8;>. 94 95=head2 Utility functions 96 97The following functions are defined in the C<utf8::> package by the 98Perl core. You do not need to say C<use utf8> to use these and in fact 99you should not say that unless you really want to have UTF-8 source code. 100 101=over 4 102 103=item * $num_octets = utf8::upgrade($string) 104 105Converts in-place the internal representation of the string from an octet 106sequence in the native encoding (Latin-1 or EBCDIC) to I<UTF-X>. The 107logical character sequence itself is unchanged. If I<$string> is already 108stored as I<UTF-X>, then this is a no-op. Returns the 109number of octets necessary to represent the string as I<UTF-X>. Can be 110used to make sure that the UTF-8 flag is on, so that C<\w> or C<lc()> 111work as Unicode on strings containing characters in the range 0x80-0xFF 112(on ASCII and derivatives). 113 114B<Note that this function does not handle arbitrary encodings.> 115Therefore Encode is recommended for the general purposes; see also 116L<Encode>. 117 118=item * $success = utf8::downgrade($string[, FAIL_OK]) 119 120Converts in-place the the internal representation of the string from 121I<UTF-X> to the equivalent octet sequence in the native encoding (Latin-1 122or EBCDIC). The logical character sequence itself is unchanged. If 123I<$string> is already stored as native 8 bit, then this is a no-op. Can 124be used to 125make sure that the UTF-8 flag is off, e.g. when you want to make sure 126that the substr() or length() function works with the usually faster 127byte algorithm. 128 129Fails if the original I<UTF-X> sequence cannot be represented in the 130native 8 bit encoding. On failure dies or, if the value of C<FAIL_OK> is 131true, returns false. 132 133Returns true on success. 134 135B<Note that this function does not handle arbitrary encodings.> 136Therefore Encode is recommended for the general purposes; see also 137L<Encode>. 138 139=item * utf8::encode($string) 140 141Converts in-place the character sequence to the corresponding octet 142sequence in I<UTF-X>. That is, every (possibly wide) character gets 143replaced with a sequence of one or more characters that represent the 144individual I<UTF-X> bytes of the character. The UTF8 flag is turned off. 145Returns nothing. 146 147 my $a = "\x{100}"; # $a contains one character, with ord 0x100 148 utf8::encode($a); # $a contains two characters, with ords 0xc4 and 0x80 149 150B<Note that this function does not handle arbitrary encodings.> 151Therefore Encode is recommended for the general purposes; see also 152L<Encode>. 153 154=item * $success = utf8::decode($string) 155 156Attempts to convert in-place the octet sequence in I<UTF-X> to the 157corresponding character sequence. That is, it replaces each sequence of 158characters in the string whose ords represent a valid UTF-X byte 159sequence, with the corresponding single character. The UTF-8 flag is 160turned on only if the source string contains multiple-byte I<UTF-X> 161characters. If I<$string> is invalid as I<UTF-X>, returns false; 162otherwise returns true. 163 164 my $a = "\xc4\x80"; # $a contains two characters, with ords 0xc4 and 0x80 165 utf8::decode($a); # $a contains one character, with ord 0x100 166 167B<Note that this function does not handle arbitrary encodings.> 168Therefore Encode is recommended for the general purposes; see also 169L<Encode>. 170 171=item * $flag = utf8::is_utf8(STRING) 172 173(Since Perl 5.8.1) Test whether STRING is in UTF-8 internally. 174Functionally 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 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>. Also, the functions utf8::is_utf8, utf8::valid, 193utf8::encode, utf8::decode, utf8::upgrade, and utf8::downgrade are 194actually internal, and thus always available, without a C<require utf8> 195statement. 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<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode> 213 214=cut 215