package utf8;
-if (ord('A') != 193) { # make things more pragmatic for EBCDIC folk
-
$utf8::hint_bits = 0x00800000;
our $VERSION = '1.00';
Carp::croak("Undefined subroutine $AUTOLOAD called");
}
-}
-
1;
__END__
=head1 NAME
-utf8 - Perl pragma to enable/disable UTF-8 in source code
+utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code
=head1 SYNOPSIS
=head1 DESCRIPTION
-WARNING: The implementation of Unicode support in Perl is incomplete.
-See L<perlunicode> for the exact details.
-
The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
-program text in the current lexical scope. The C<no utf8> pragma
-tells Perl to switch back to treating the source text as literal
-bytes in the current lexical scope.
+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.
This pragma is primarily a compatibility device. Perl versions
earlier than 5.6 allowed arbitrary bytes in source code, whereas
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. This pragma already is a no-op on
-EBCDIC platforms (where it is alright to code perl in EBCDIC
-rather than UTF-8).
+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.
-Enabling the C<utf8> pragma has the following effects:
+Enabling the C<utf8> pragma has the following effect:
-=over
+=over 4
=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.
-
-=item *
-
-In the absence of inputs marked as UTF-8, regular expressions within the
-scope of this pragma will default to using character semantics instead
-of byte semantics.
-
- @bytes_or_chars = split //, $data; # may split to bytes if data
- # $data isn't UTF-8
- {
- use utf8; # force char semantics
- @chars = split //, $data; # splits characters
- }
+as being part of a literal UTF-8 character. 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;>.
+
+=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 unless you really want to have UTF-8 source code.
+
+=over 4
+
+=item * $num_octets = utf8::upgrade($string);
+
+Converts (in-place) internal representation of string to Perl's
+internal I<UTF-X> form. 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 expected on strings
+containing characters in the range 0x80-0xFF (oon ASCII and
+derivatives). Note that this should not be used to convert a legacy
+byte encoding to Unicode: use Encode for that. Affected by the
+encoding pragma.
+
+=item * utf8::downgrade($string[, FAIL_OK])
+
+Converts (in-place) internal representation of string to be un-encoded
+bytes. Returns true on success. On failure dies or, if the value of
+FAIL_OK is true, returns false. Can be used to make sure that the
+UTF-8 flag is off, e.g. when you want to make sure that the substr()
+or length() function works with the usually faster byte algorithm.
+Note that this should not be used to convert Unicode back to a legacy
+byte encoding: use Encode for that. B<Not> affected by the encoding
+pragma.
+
+=item * utf8::encode($string)
+
+Converts (in-place) I<$string> from logical characters to octet
+sequence representing it in Perl's I<UTF-X> encoding. Returns
+nothing. Same as Encode::encode_utf8(). Note that this should not be
+used to convert a legacy byte encoding to Unicode: use Encode for
+that.
+
+=item * $flag = utf8::decode($string)
+
+Attempts to convert I<$string> in-place from Perl's I<UTF-X> encoding
+into logical characters. Returns nothing. Same as Encode::decode_utf8().
+Note that this should not be used to convert Unicode back to a legacy
+byte encoding: use Encode for that.
+
+=item * $flag = utf8::is_utf8(STRING)
+
+Test whether STRING is in UTF-8. 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>. Note that in the Perl 5.8.0 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
https://perl5.git.perl.org / perl5.git / blobdiff