package utf8; $utf8::hint_bits = 0x00800000; our $VERSION = '1.09'; sub import { $^H |= $utf8::hint_bits; $enc{caller()} = $_[1] if $_[1]; } sub unimport { $^H &= ~$utf8::hint_bits; } sub AUTOLOAD { require "utf8_heavy.pl"; goto &$AUTOLOAD if defined &$AUTOLOAD; require Carp; Carp::croak("Undefined subroutine $AUTOLOAD called"); } 1; __END__ =head1 NAME utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code =head1 SYNOPSIS use utf8; no utf8; # Convert the internal representation of a Perl scalar to/from UTF-8. $num_octets = utf8::upgrade($string); $success = utf8::downgrade($string[, FAIL_OK]); # Change each character of a Perl scalar to/from a series of # characters that represent the UTF-8 bytes of each original character. utf8::encode($string); # "\x{100}" becomes "\xc4\x80" utf8::decode($string); # "\xc4\x80" becomes "\x{100}" $flag = utf8::is_utf8(STRING); # since Perl 5.8.1 $flag = utf8::valid(STRING); =head1 DESCRIPTION The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based platforms). The C<no utf8> pragma tells Perl to switch back to treating the source text as literal bytes in the current lexical scope. B<Do not use this pragma for anything else than telling Perl that your script is written in UTF-8.> The utility functions described below are directly usable without C<use utf8;>. Because it is not possible to reliably tell UTF-8 from native 8 bit encodings, you need either a Byte Order Mark at the beginning of your source code, or C<use utf8;>, to instruct perl. When UTF-8 becomes the standard source format, this pragma will effectively become a no-op. For convenience in what follows the term I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based platforms and UTF-EBCDIC on EBCDIC based platforms. See also the effects of the C<-C> switch and its cousin, the C<$ENV{PERL_UNICODE}>, in L<perlrun>. Enabling the C<utf8> pragma has the following effect: =over 4 =item * Bytes in the source text that have their high-bit set will be treated as being part of a literal UTF-X sequence. This includes most literals such as identifier names, string constants, and constant regular expression patterns. On EBCDIC platforms characters in the Latin 1 character set are treated as being part of a literal UTF-EBCDIC character. =back Note that if you have bytes with the eighth bit on in your script (for example embedded Latin-1 in your string literals), C<use utf8> will be unhappy since the bytes are most probably not well-formed UTF-X. If you want to have such bytes under C<use utf8>, you can disable this pragma until the end the block (or file, if at top level) by C<no utf8;>. =head2 Utility functions The following functions are defined in the C<utf8::> package by the Perl core. You do not need to say C<use utf8> to use these and in fact you should not say that unless you really want to have UTF-8 source code. =over 4 =item * $num_octets = utf8::upgrade($string) Converts in-place the internal representation of the string from an octet sequence in the native encoding (Latin-1 or EBCDIC) to I<UTF-X>. The logical character sequence itself is unchanged. If I<$string> is already stored as I<UTF-X>, then this is a no-op. Returns the number of octets necessary to represent the string as I<UTF-X>. Can be used to make sure that the UTF-8 flag is on, so that C<\w> or C<lc()> work as Unicode on strings containing characters in the range 0x80-0xFF (on ASCII and derivatives). B<Note that this function does not handle arbitrary encodings.> Therefore Encode is recommended for the general purposes; see also L<Encode>. =item * $success = utf8::downgrade($string[, FAIL_OK]) Converts in-place the internal representation of the string from I<UTF-X> to the equivalent octet sequence in the native encoding (Latin-1 or EBCDIC). The logical character sequence itself is unchanged. If I<$string> is already stored as native 8 bit, then this is a no-op. Can be used to make sure that the UTF-8 flag is off, e.g. when you want to make sure that the substr() or length() function works with the usually faster byte algorithm. Fails if the original I<UTF-X> sequence cannot be represented in the native 8 bit encoding. On failure dies or, if the value of C<FAIL_OK> is true, returns false. Returns true on success. B<Note that this function does not handle arbitrary encodings.> Therefore Encode is recommended for the general purposes; see also L<Encode>. =item * utf8::encode($string) Converts in-place the character sequence to the corresponding octet sequence in I<UTF-X>. That is, every (possibly wide) character gets replaced with a sequence of one or more characters that represent the individual I<UTF-X> bytes of the character. The UTF8 flag is turned off. Returns nothing. my $a = "\x{100}"; # $a contains one character, with ord 0x100 utf8::encode($a); # $a contains two characters, with ords 0xc4 and 0x80 B<Note that this function does not handle arbitrary encodings.> Therefore Encode is recommended for the general purposes; see also L<Encode>. =item * $success = utf8::decode($string) Attempts to convert in-place the octet sequence in I<UTF-X> to the corresponding character sequence. That is, it replaces each sequence of characters in the string whose ords represent a valid UTF-X byte sequence, with the corresponding single character. The UTF-8 flag is turned on only if the source string contains multiple-byte I<UTF-X> characters. If I<$string> is invalid as I<UTF-X>, returns false; otherwise returns true. my $a = "\xc4\x80"; # $a contains two characters, with ords 0xc4 and 0x80 utf8::decode($a); # $a contains one character, with ord 0x100 B<Note that this function does not handle arbitrary encodings.> Therefore Encode is recommended for the general purposes; see also L<Encode>. =item * $flag = utf8::is_utf8(STRING) (Since Perl 5.8.1) Test whether STRING is in UTF-8 internally. Functionally the same as Encode::is_utf8(). =item * $flag = utf8::valid(STRING) [INTERNAL] Test whether STRING is in a consistent state regarding UTF-8. Will return true is well-formed UTF-8 and has the UTF-8 flag on B<or> if string is held as bytes (both these states are 'consistent'). Main reason for this routine is to allow Perl's testsuite to check that operations have left strings in a consistent state. You most probably want to use utf8::is_utf8() instead. =back C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is cleared. See L<perlunicode> for more on the UTF8 flag and the C API functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>, and C<sv_utf8_decode>, which are wrapped by the Perl functions C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and C<utf8::decode>. Also, the functions utf8::is_utf8, utf8::valid, utf8::encode, utf8::decode, utf8::upgrade, and utf8::downgrade are actually internal, and thus always available, without a C<require utf8> statement. =head1 BUGS One can have Unicode in identifier names, but not in package/class or subroutine names. While some limited functionality towards this does exist as of Perl 5.8.0, that is more accidental than designed; use of Unicode for the said purposes is unsupported. One reason of this unfinishedness is its (currently) inherent unportability: since both package names and subroutine names may need to be mapped to file and directory names, the Unicode capability of the filesystem becomes important-- and there unfortunately aren't portable answers. =head1 SEE ALSO L<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode> =cut