package utf8;
+$utf8::hint_bits = 0x00800000;
+
+our $VERSION = '1.00';
+
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;
+ 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
=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:
-
-=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 C<-w> is turned on, it will
-produce a warning that you might be generating invalid UTF-8.
-
-=item *
-
-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.)
-
-=item *
+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.
-Regular expressions match characters instead of bytes. For instance,
-"." matches a character instead of a byte. (However, the C<\O> pattern
-is provided to force a match a single byte ("octet", hence C<\O>).)
+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.
+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.
-=item *
-
-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.
-
-=item *
+Enabling the C<utf8> pragma has the following effect:
-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}>.
-
-=item *
-
-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*)>.
+=over 4
=item *
-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:
+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 Latin 1 character set are treated as being part of a literal
+UTF-EBCDIC character.
- use utf8;
- while (<>) {
- tr/\0-\xff//CU; # latin1 char to utf8
- ...
- }
-
-Similarly you could translate your output with
+=back
- tr/\0-\x{ff}//UC; # utf8 to latin1 char
+=head2 Utility functions
-No, C<s///> doesn't take /U or /C (yet?).
+The following functions are defined in the C<utf8::> package by the perl core.
-=item *
+=over 4
-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.
+=item * $num_octets = utf8::upgrade($string);
-=item *
+Converts internal representation of string to the Perl's internal
+I<UTF-X> form. Returns the number of octets necessary to represent
+the string as I<UTF-X>.
-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.
+=item * utf8::downgrade($string[, CHECK])
-=item *
+Converts internal representation of string to be un-encoded bytes.
-The C<pack()>/C<unpack()> letters "C<c>" and "C<C>" do I<not> change,
-since they're often used for byte-oriented formats. (Again, think
-"C<char>" in the C language.) However, there is a new "C<U>" specifier
-that will convert between UTF-8 characters and integers. (It works
-outside of the utf8 pragma too.)
+=item * utf8::encode($string)
-=item *
+Converts (in-place) I<$string> from logical characters to octet sequence
+representing it in Perl's I<UTF-X> encoding.
-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.
+=item * $flag = utf8::decode($string)
-=item *
-
-And finally, C<scalar reverse()> reverses by character rather than by byte.
+Attempts to convert I<$string> in-place from Perl's I<UTF-X> encoding
+into logical characters.
=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.
+=head1 SEE ALSO
+
+L<perlunicode>, L<bytes>
=cut
https://perl5.git.perl.org / perl5.git / blobdiff