package utf8;
+$utf8::hint_bits = 0x00800000;
+
+our $VERSION = '1.08';
+
sub import {
- $^H |= 0x00000008;
+ $^H |= $utf8::hint_bits;
$enc{caller()} = $_[1] if $_[1];
}
sub unimport {
- $^H &= ~0x00000008;
+ $^H &= ~$utf8::hint_bits;
}
sub AUTOLOAD {
require "utf8_heavy.pl";
- goto &$AUTOLOAD;
+ goto &$AUTOLOAD if defined &$AUTOLOAD;
+ require Carp;
+ Carp::croak("Undefined subroutine $AUTOLOAD called");
}
1;
=head1 NAME
-utf8 - Perl pragma to turn on UTF-8 and Unicode support
+utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code
=head1 SYNOPSIS
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]);
+
+ # 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
+ $flag = utf8::valid(STRING);
+
=head1 DESCRIPTION
-The utf8 pragma tells Perl to use UTF-8 as its internal string
-representation for the rest of the enclosing block. (The "no utf8"
-pragma tells Perl to switch back to ordinary byte-oriented processing
-for the rest of the enclosing block.) Under utf8, many operations that
-formerly operated on bytes change to operating on characters. For
-ASCII data this makes no difference, because UTF-8 stores ASCII in
-single bytes, but for any character greater than C<chr(127)>, the
-character is stored in a sequence of two or more bytes, all of which
-have the high bit set. But by and large, the user need not worry about
-this, because the utf8 pragma hides it from the user. A character
-under utf8 is logically just a number ranging from 0 to 2**32 or so.
-Larger characters encode to longer sequences of bytes, but again, this
-is hidden.
-
-Use of the utf8 pragma has the following effects:
+The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
+program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based
+platforms). The C<no utf8> pragma tells Perl to switch back to treating
+the source text as literal bytes in the current lexical scope.
+
+B<Do not use this pragma for anything else than telling Perl that your
+script is written in UTF-8.> The utility functions described below are
+directly usable without C<use utf8;>.
+
+Because it is not possible to reliably tell UTF-8 from native 8 bit
+encodings, you need either a Byte Order Mark at the beginning of your
+source code, or C<use utf8;>, to instruct perl.
+
+When UTF-8 becomes the standard source format, this pragma will
+effectively become a no-op. For convenience in what follows the term
+I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based
+platforms and UTF-EBCDIC on EBCDIC based platforms.
+
+See also the effects of the C<-C> switch and its cousin, the
+C<$ENV{PERL_UNICODE}>, in L<perlrun>.
+
+Enabling the C<utf8> pragma has the following effect:
=over 4
=item *
-Strings and patterns may contain characters that have an ordinal value
-larger than 255. Presuming you use a Unicode editor to edit your
-program, these will typically occur directly within the literal strings
-as UTF-8 characters, but you can also specify a particular character
-with an extension of the C<\x> notation. UTF-8 characters are
-specified by putting the hexadecimal code within curlies after the
-C<\x>. For instance, a Unicode smiley face is C<\x{263A}>. A
-character in the Latin-1 range (128..255) should be written C<\x{ab}>
-rather than C<\xab>, since the former will turn into a two-byte UTF-8
-code, while the latter will continue to be interpreted as generating a
-8-bit byte rather than a character. In fact, if -w is turned on, it will
-produce a warning that you might be generating invalid UTF-8.
+Bytes in the source text that have their high-bit set will be treated
+as being part of a literal UTF-X sequence. This includes most
+literals such as identifier names, string constants, and constant
+regular expression patterns.
-=item *
+On EBCDIC platforms characters in the Latin 1 character set are
+treated as being part of a literal UTF-EBCDIC character.
-Identifiers within the Perl script may contain Unicode alphanumeric
-characters, including ideographs. (You are currently on your own when
-it comes to using the canonical forms of characters--Perl doesn't (yet)
-attempt to canonicalize variable names for you.)
+=back
-=item *
+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-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;>.
-Regular expressions match characters instead of bytes. For instance,
-"." matches a character instead of a byte. (However, the C<\C> pattern
-is provided to force a match a single byte ("C<char>" in C, hence
-C<\C>).)
+=head2 Utility functions
-=item *
+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.
-Character classes in regular expressions match characters instead of
-bytes, and match against the character properties specified in the
-Unicode properties database. So C<\w> can be used to match an ideograph,
-for instance.
+=over 4
-=item *
+=item * $num_octets = utf8::upgrade($string)
-Named Unicode properties and block ranges make be used as character
-classes via the new C<\p{}> (matches property) and C<\P{}> (doesn't
-match property) constructs. For instance, C<\p{Lu}> matches any
-character with the Unicode uppercase property, while C<\p{M}> matches
-any mark character. Single letter properties may omit the brackets, so
-that can be written C<\pM> also. Many predefined character classes are
-available, such as C<\p{IsMirrored}> and C<\p{InTibetan}>.
+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).
-=item *
+B<Note that this function does not handle arbitrary encodings.>
+Therefore Encode is recommended for the general purposes; see also
+L<Encode>.
-The special pattern C<\X> match matches any extended Unicode sequence
-(a "combining character sequence" in Standardese), where the first
-character is a base character and subsequent characters are mark
-characters that apply to the base character. It is equivalent to
-C<(?:\PM\pM*)>.
+=item * $success = utf8::downgrade($string[, FAIL_OK])
-=item *
+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<$string> is already stored as native 8 bit, then this is a no-op. Can
+be used to
+make sure that the UTF-8 flag is off, e.g. when you want to make sure
+that the substr() or length() function works with the usually faster
+byte algorithm.
-The C<tr///> operator translates characters instead of bytes. It can also
-be forced to translate between 8-bit codes and UTF-8 regardless of the
-surrounding utf8 state. For instance, if you know your input in Latin-1,
-you can say:
+Fails if the original I<UTF-X> sequence cannot be represented in the
+native 8 bit encoding. On failure dies or, if the value of C<FAIL_OK> is
+true, returns false.
- use utf8;
- while (<>) {
- tr/\0-\xff//CU; # latin1 char to utf8
- ...
- }
+Returns true on success.
-Similarly you could translate your output with
+B<Note that this function does not handle arbitrary encodings.>
+Therefore Encode is recommended for the general purposes; see also
+L<Encode>.
- tr/\0-\x{ff}//UC; # utf8 to latin1 char
+=item * utf8::encode($string)
-No, C<s///> doesn't take /U or /C (yet?).
+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.
-=item *
+ my $a = "\x{100}"; # $a contains one character, with ord 0x100
+ utf8::encode($a); # $a contains two characters, with ords 0xc4 and 0x80
-Case translation operators use the Unicode case translation tables.
-Note that C<uc()> translates to uppercase, while C<ucfirst> translates
-to titlecase (for languages that make the distinction). Naturally
-the corresponding backslash sequences have the same semantics.
+B<Note that this function does not handle arbitrary encodings.>
+Therefore Encode is recommended for the general purposes; see also
+L<Encode>.
-=item *
+=item * $success = utf8::decode($string)
-Most operators that deal with positions or lengths in the string will
-automatically switch to using character positions, including C<chop()>,
-C<substr()>, C<pos()>, C<index()>, C<rindex()>, C<sprintf()>,
-C<write()>, and C<length()>. Operators that specifically don't switch
-include C<vec()>, C<pack()>, and C<unpack()>. Operators that really
-don't care include C<chomp()>, as well as any other operator that
-treats a string as a bucket of bits, such as C<sort()>, and the
-operators dealing with filenames.
+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 *
+ my $a = "\xc4\x80"; # $a contains two characters, with ords 0xc4 and 0x80
+ utf8::decode($a); # $a contains one character, with ord 0x100
-The C<pack()>/C<unpack()> letters "C<c>" and "C<C>" do I<not> change,
-since they're often used for byte-oriented formats. (Again, think
-"C<char>" in the C language.) However, there is a new "C<U>" specifier
-that will convert between UTF-8 characters and integers. (It works
-outside of the utf8 pragma too.)
+B<Note that this function does not handle arbitrary encodings.>
+Therefore Encode is recommended for the general purposes; see also
+L<Encode>.
-=item *
+=item * $flag = utf8::is_utf8(STRING)
-The C<chr()> and C<ord()> functions work on characters. This is like
-C<pack("U")> and C<unpack("U")>, not like C<pack("C")> and
-C<unpack("C")>. In fact, the latter are how you now emulate
-byte-oriented C<chr()> and C<ord()> under utf8.
+(Since Perl 5.8.1) Test whether STRING is in UTF-8 internally.
+Functionally the same as Encode::is_utf8().
-=item *
+=item * $flag = utf8::valid(STRING)
-And finally, C<scalar reverse()> reverses by character rather than by byte.
+[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
-=head1 CAVEATS
-
-As of yet, there is no method for automatically coercing input and
-output to some encoding other than UTF-8. This is planned in the near
-future, however.
-
-In any event, you'll need to keep track of whether interfaces to other
-modules expect UTF-8 data or something else. The utf8 pragma does not
-magically mark strings for you in order to remember their encoding, nor
-will any automatic coercion happen (other than that eventually planned
-for I/O). If you want such automatic coercion, you can build yourself
-a set of pretty object-oriented modules. Expect it to run considerably
-slower than than this low-level support.
-
-Use of locales with utf8 may lead to odd results. Currently there is
-some attempt to apply 8-bit locale info to characters in the range
-0..255, but this is demonstrably incorrect for locales that use
-characters above that range (when mapped into Unicode). It will also
-tend to run slower. Avoidance of locales is strongly encouraged.
+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>. 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
+
+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<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode>
=cut
https://perl5.git.perl.org / perl5.git / blobdiff