$utf8::hint_bits = 0x00800000;
-our $VERSION = '1.00';
+our $VERSION = '1.06';
sub import {
$^H |= $utf8::hint_bits;
sub AUTOLOAD {
require "utf8_heavy.pl";
goto &$AUTOLOAD if defined &$AUTOLOAD;
+ require Carp;
Carp::croak("Undefined subroutine $AUTOLOAD called");
}
use utf8;
no utf8;
+ # Convert a Perl scalar to/from UTF-8.
+ $num_octets = utf8::upgrade($string);
+ $success = utf8::downgrade($string[, FAIL_OK]);
+
+ # Change the native bytes of a Perl scalar to/from UTF-8 bytes.
+ utf8::encode($string);
+ utf8::decode($string);
+
+ $flag = utf8::is_utf8(STRING); # since Perl 5.8.1
+ $flag = utf8::valid(STRING);
+
=head1 DESCRIPTION
The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
This pragma is primarily a compatibility device. Perl versions
earlier than 5.6 allowed arbitrary bytes in source code, whereas
in future we would like to standardize on the UTF-8 encoding for
-source text. Until UTF-8 becomes the default format for source
-text, this pragma should be used to recognize UTF-8 in the source.
-When UTF-8 becomes the standard source format, this pragma will
-effectively become a no-op. For convenience in what follows the
-term I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based
-platforms and UTF-EBCDIC on EBCDIC based platforms.
+source text.
+
+B<Do not use this pragma for anything else than telling Perl that your
+script is written in UTF-8.> The utility functions described below are
+useful for their own purposes, but they are not really part of the
+"pragmatic" effect.
+
+Until UTF-8 becomes the default format for source text, either this
+pragma or the L<encoding> pragma should be used to recognize UTF-8
+in the source. When UTF-8 becomes the standard source format, this
+pragma will effectively become a no-op. For convenience in what
+follows the term I<UTF-X> is used to refer to UTF-8 on ASCII and ISO
+Latin based platforms and UTF-EBCDIC on EBCDIC based platforms.
+
+See also the effects of the C<-C> switch and its cousin, the
+C<$ENV{PERL_UNICODE}>, in L<perlrun>.
Enabling the C<utf8> pragma has the following effect:
=item *
Bytes in the source text that have their high-bit set will be treated
-as being part of a literal UTF-8 character. This includes most
-literals such as identifiers, string constants, constant regular
-expression patterns and package names. On EBCDIC platforms characters
-in the Latin 1 character set are treated as being part of a literal
-UTF-EBCDIC character.
+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-8. If you want to have such bytes and use utf8, you can disable
-utf8 until the end the block (or file, if at top level) by C<no utf8;>.
+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;>.
+
+If you want to automatically upgrade your 8-bit legacy bytes to Unicode,
+use the L<encoding> pragma instead of this pragma. For example, if
+you want to implicitly upgrade your ISO 8859-1 (Latin-1) bytes to Unicode
+as used in e.g. C<chr()> and C<\x{...}>, try this:
+
+ use encoding "latin-1";
+ my $c = chr(0xc4);
+ my $x = "\x{c5}";
+
+In case you are wondering: C<use encoding 'utf8';> is mostly the same as
+C<use utf8;>, except that C<use encoding> marks all string literals in the
+source code as Unicode, regardless of whether they contain any high-bit bytes.
+Moreover, C<use encoding> installs IO layers on C<STDIN> and C<STDOUT> to work
+with Unicode strings; see L<encoding> for details.
=head2 Utility functions
-The following functions are defined in the C<utf8::> package by the perl core.
+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);
+=item * $num_octets = utf8::upgrade($string)
+
+Converts in-place the octet sequence in the native encoding
+(Latin-1 or EBCDIC) to the equivalent character sequence in I<UTF-X>.
+I<$string> already encoded as characters does no harm.
+Returns the number of octets necessary to represent the string as I<UTF-X>.
+Can be used to make sure that the UTF-8 flag is on,
+so that C<\w> or C<lc()> work as Unicode on strings
+containing characters in the range 0x80-0xFF (on ASCII and
+derivatives).
+
+B<Note that this function does not handle arbitrary encodings.>
+Therefore I<Encode.pm> is recommended for the general purposes.
-Converts internal representation of string to the Perl's internal
-I<UTF-X> form. Returns the number of octets necessary to represent
-the string as I<UTF-X>. Note that this should not be used to convert
-a legacy byte encoding to Unicode: use Encode for that. Affected
-by the encoding pragma.
+Affected by the encoding pragma.
-=item * utf8::downgrade($string[, CHECK])
+=item * $success = utf8::downgrade($string[, FAIL_OK])
-Converts internal representation of string to be un-encoded bytes.
-Note that this should not be used to convert Unicode back to a legacy
-byte encoding: use Encode for that. B<Not> affected by the encoding
-pragma.
+Converts in-place the character sequence in I<UTF-X>
+to the equivalent octet sequence in the native encoding (Latin-1 or EBCDIC).
+I<$string> already encoded as octets does no harm.
+Returns true on success. On failure dies or, if the value of
+C<FAIL_OK> is true, returns false.
+Can be used to make sure that the UTF-8 flag is off,
+e.g. when you want to make sure that the substr() or length() function
+works with the usually faster byte algorithm.
+
+B<Note that this function does not handle arbitrary encodings.>
+Therefore I<Encode.pm> is recommended for the general purposes.
+
+B<Not> affected by the encoding pragma.
+
+B<NOTE:> this function is experimental and may change
+or be removed without notice.
=item * utf8::encode($string)
-Converts (in-place) I<$string> from logical characters to octet
-sequence representing it in Perl's I<UTF-X> encoding. Note that this
-should not be used to convert a legacy byte encoding to Unicode: use
-Encode for that.
+Converts in-place the character sequence to the corresponding octet sequence
+in I<UTF-X>. The UTF-8 flag is turned off. Returns nothing.
+
+B<Note that this function does not handle arbitrary encodings.>
+Therefore I<Encode.pm> is recommended for the general purposes.
+
+=item * utf8::decode($string)
+
+Attempts to convert in-place the octet sequence in I<UTF-X>
+to the corresponding character sequence. 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.
-=item * $flag = utf8::decode($string)
+B<Note that this function does not handle arbitrary encodings.>
+Therefore I<Encode.pm> is recommended for the general purposes.
-Attempts to convert I<$string> in-place from Perl's I<UTF-X> encoding
-into logical characters. Note that this should not be used to convert
-Unicode back to a legacy byte encoding: use Encode for that.
+B<NOTE:> this function is experimental and may change
+or be removed without notice.
+
+=item * $flag = utf8::is_utf8(STRING)
+
+(Since Perl 5.8.1) Test whether STRING is in UTF-8. Functionally
+the same as Encode::is_utf8().
=item * $flag = utf8::valid(STRING)
-[INTERNAL] Test whether STRING is in a consistent state. Will return
-true if string is held as bytes, or is well-formed UTF-8 and has the
-UTF-8 flag on. Main reason for this routine is to allow Perl's
-testsuite to check that operations have left strings in a consistent
-state.
+[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>,
+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>.
+C<utf8::decode>. Note that in the Perl 5.8.0 and 5.8.1 implementation
+the functions utf8::is_utf8, utf8::valid, utf8::encode, utf8::decode,
+utf8::upgrade, and utf8::downgrade are always available, without a
+C<require utf8> statement-- this may change in future releases.
+
+=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<perlunicode>, L<bytes>
+L<perluniintro>, L<encoding>, L<perlrun>, L<bytes>, L<perlunicode>
=cut
https://perl5.git.perl.org / perl5.git / blobdiff