$utf8::hint_bits = 0x00800000;
-our $VERSION = '1.05';
+our $VERSION = '1.10';
sub import {
$^H |= $utf8::hint_bits;
use utf8;
no utf8;
- # Convert a Perl scalar to/from UTF-8.
+ # Convert the internal representation of 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);
+ # 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
$flag = utf8::valid(STRING);
platforms). The C<no utf8> pragma tells Perl to switch back to treating
the source text as literal bytes in the current lexical scope.
-This pragma is primarily a compatibility device. Perl versions
-earlier than 5.6 allowed arbitrary bytes in source code, whereas
-in future we would like to standardize on the UTF-8 encoding for
-source text.
-
B<Do not use this pragma for anything else than telling Perl that your
script is written in UTF-8.> The utility functions described below are
-useful for their own purposes, but they are not really part of the
-"pragmatic" effect.
+directly usable without C<use utf8;>.
+
+Because it is not possible to reliably tell UTF-8 from native 8 bit
+encodings, you need either a Byte Order Mark at the beginning of your
+source code, or C<use utf8;>, to instruct perl.
-Until UTF-8 becomes the default format for source text, either this
-pragma or the L</encoding> pragma should be used to recognize UTF-8
-in the source. When UTF-8 becomes the standard source format, this
-pragma will effectively become a no-op. For convenience in what
-follows the term I<UTF-X> is used to refer to UTF-8 on ASCII and ISO
-Latin based platforms and UTF-EBCDIC on EBCDIC based platforms.
+When UTF-8 becomes the standard source format, this pragma will
+effectively become a no-op. For convenience in what follows the term
+I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based
+platforms and UTF-EBCDIC on EBCDIC based platforms.
See also the effects of the C<-C> switch and its cousin, the
C<$ENV{PERL_UNICODE}>, in L<perlrun>.
=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;>.
-
-If you want to automatically upgrade your 8-bit legacy bytes to UTF-8,
-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 UTF-8
-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: yes, C<use encoding 'utf8';> works much
-the same as C<use 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
=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<$string> already encoded as characters does no harm.
-Returns the number of octets necessary to represent the string as I<UTF-X>.
-Can be used to make sure that the UTF-8 flag is on,
-so that C<\w> or C<lc()> work as Unicode on strings
-containing characters in the range 0x80-0xFF (on ASCII and
-derivatives).
+Converts in-place the internal representation of the string from an octet
+sequence in the native encoding (Latin-1 or EBCDIC) to I<UTF-X>. The
+logical character sequence itself is unchanged. If I<$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 I<Encode.pm> is recommended for the general purposes.
-
-Affected by the encoding pragma.
+Therefore Encode is recommended for the general purposes; see also
+L<Encode>.
=item * $success = utf8::downgrade($string[, FAIL_OK])
-Converts in-place the character sequence in I<UTF-X>
-to the equivalent octet sequence in the native encoding (Latin-1 or EBCDIC).
-I<$string> already encoded as octets does no harm.
-Returns true on success. On failure dies or, if the value of
-C<FAIL_OK> is true, returns false.
-Can be used to make sure that the UTF-8 flag is off,
-e.g. when you want to make sure that the substr() or length() function
-works with the usually faster byte algorithm.
+Converts in-place the internal representation of the string from
+I<UTF-X> to the equivalent octet sequence in the native encoding (Latin-1
+or EBCDIC). The logical character sequence itself is unchanged. If
+I<$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.
-B<Note that this function does not handle arbitrary encodings.>
-Therefore I<Encode.pm> is recommended for the general purposes.
+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.
-B<Not> affected by the encoding pragma.
+Returns true on success.
-B<NOTE:> this function is experimental and may change
-or be removed without notice.
+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>. The UTF-8 flag is turned off. Returns nothing.
+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); # $a contains two characters, with ords 0xc4 and 0x80
B<Note that this function does not handle arbitrary encodings.>
-Therefore I<Encode.pm> is recommended for the general purposes.
+Therefore Encode is recommended for the general purposes; see also
+L<Encode>.
-=item * utf8::decode($string)
+=item * $success = utf8::decode($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<$string> is invalid as I<UTF-X>, returns false; otherwise returns true.
+Attempts to convert in-place the octet sequence in I<UTF-X> to the
+corresponding character sequence. That is, it replaces each sequence of
+characters in the string whose ords represent a valid UTF-X byte
+sequence, with the corresponding single character. The UTF-8 flag is
+turned on only if the source string contains multiple-byte I<UTF-X>
+characters. If I<$string> is invalid as I<UTF-X>, returns false;
+otherwise returns true.
-B<Note that this function does not handle arbitrary encodings.>
-Therefore I<Encode.pm> is recommended for the general purposes.
+ 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:> this function is experimental and may change
-or be removed without notice.
+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 encoded internally in UTF-8.
+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').
+UTF-8. Will return true if it 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.
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<perluni
intro>, L<encoding>, L<perlrun>, L<bytes>, L<perlunicode>
+L<perluni
tut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode>
=cut
https://perl5.git.perl.org / perl5.git / blobdiff