package utf8;
-
$utf8::hint_bits = 0x00800000;
our $VERSION = '1.00';
=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 (allow UTF-EBCDIC on EBCDIC based
-platforms). The C<no utf8> pragma tells Perl to switch back to treating
+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
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 UTF-X is used to refer to UTF-8 on ASCII and ISO Latin based
+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 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. On EBCDIC platforms, characters in the C1 control group
-and the Latin 1 character set are treated as being part of a literal
+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.
-=item *
-
-In the absence of inputs marked as UTF-X, 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-X
- {
- use utf8; # force char semantics
- @chars = split //, $data; # splits characters
- }
-
=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.
=item * $num_octets = utf8::upgrade($string);
-Converts internal representation of string to the perls internal UTF-X form.
-Returns the number of octets necessary to represent the string as UTF-X.
-
-=item * utf8::downgrade($string[, CHECK])
-
-Converts internal representation of string to be un-encoded bytes.
+Converts (in-place) internal representation of string to Perl's internal
+I<UTF-X> form. Returns the number of octets necessary to represent
+the string as I<UTF-X>. Can be used to make sure that the
+UTF-8 flag is on, so that C<\w> or C<lc()> work as expected on strings
+containing characters in the range 0x80-0xFF. Note that this should
+not be used to convert
+a legacy byte encoding to Unicode: use Encode for that. Affected
+by the encoding pragma.
+
+=item * utf8::downgrade($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 UTF-X encoding.
+Converts (in-place) I<$string> from logical characters to octet
+sequence representing it in Perl's I<UTF-X> encoding. 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<$string> in-place from perl's UTF-X encoding into logical characters.
+Attempts to convert I<$string> in-place from Perl's I<UTF-X> encoding
+into logical characters. 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::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.
=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::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 SEE ALSO
L<perlunicode>, L<bytes>
https://perl5.git.perl.org / perl5.git / blobdiff