$utf8::hint_bits = 0x00800000;
-our $VERSION = '1.02';
+our $VERSION = '1.08';
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 the internal representation of a Perl scalar to/from UTF-8.
+
$num_octets = utf8::upgrade($string);
$success = utf8::downgrade($string[, FAIL_OK]);
- utf8::encode($string);
- utf8::decode($string);
+ # 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
$flag = utf8::valid(STRING);
platforms). The C<no utf8> pragma tells Perl to switch back to treating
the source text as literal bytes in the current lexical scope.
-This pragma is primarily a compatibility device. Perl versions
-earlier than 5.6 allowed arbitrary bytes in source code, whereas
-in future we would like to standardize on the UTF-8 encoding for
-source text. Until UTF-8 becomes the default format for source
-text, this pragma should be used to recognize UTF-8 in the source.
+B<Do not use this pragma for anything else than telling Perl that your
+script is written in UTF-8.> The utility functions described below are
+directly usable without C<use utf8;>.
+
+Because it is not possible to reliably tell UTF-8 from native 8 bit
+encodings, you need either a Byte Order Mark at the beginning of your
+source code, or C<use utf8;>, to instruct perl.
+
When UTF-8 becomes the standard source format, this pragma will
-effectively become a no-op. For convenience in what follows the
-term I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based
+effectively become a no-op. For convenience in what follows the term
+I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based
platforms and UTF-EBCDIC on EBCDIC based platforms.
+See also the effects of the C<-C> switch and its cousin, the
+C<$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-8 character. This includes most
+as being part of a literal UTF-X sequence. This includes most
literals such as identifier names, string constants, and constant
regular expression patterns.
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;>.
=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.
+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) 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.
+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) 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.
+Converts in-place the 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) 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.
+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<$string> is invalid as I<UTF-X>, returns false;
+otherwise returns true.
-=item * utf8::decode($string)
+ my $a = "\xc4\x80"; # $a contains two characters, with ords 0xc4 and 0x80
+ utf8::decode($a); # $a contains one character, with ord 0x100
-Attempts to convert I<$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.
+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. Functionally
-the same as Encode::is_utf8().
+(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)
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 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.
+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
=head1 SEE ALSO
-L<perluniintro>, L<perlunicode>, L<bytes>
+L<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode>
=cut
https://perl5.git.perl.org / perl5.git / blobdiff