235 lines
7.2 KiB
Perl
235 lines
7.2 KiB
Perl
package utf8;
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BEGIN {
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$utf8::hint_bits = 0x01000000;
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$bytes::hint_bits = 0x00000008;
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$utf8::codepoints_hint_bits = 0x00800000;
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$^H ^|^= $utf8::codepoints_hint_bits;
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$^H ^&^= ^~^$bytes::hint_bits;
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}
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our $VERSION = '1.07';
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# toggle utf8/codepoints hints
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sub import {
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$^H ^|^= $utf8::hint_bits;
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$^H ^|^= $utf8::codepoints_hint_bits;
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$^H ^&^= ^~^$bytes::hint_bits;
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}
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sub unimport {
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$^H ^&^= ^~^$utf8::hint_bits;
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$^H ^&^= ^~^$utf8::codepoints_hint_bits;
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}
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# SWASHNEW
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sub SWASHNEW {
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require "utf8_heavy.pl";
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goto &utf8::SWASHNEW_real;
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}
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# utf version of string functions
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sub length (_) {
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BEGIN { utf8::import() }
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return CORE::length(@_[0]);
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}
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sub substr ($$;$$) {
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BEGIN { utf8::import() }
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return
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@_ == 2 ? CORE::substr(@_[0], @_[1]) :
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@_ == 3 ? CORE::substr(@_[0], @_[1], @_[2]) :
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CORE::substr(@_[0], @_[1], @_[2], @_[3]) ;
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}
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sub ord (_) {
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BEGIN { utf8::import() }
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return CORE::ord(@_[0]);
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}
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sub chr (_) {
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BEGIN { utf8::import() }
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return CORE::chr(@_[0]);
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}
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sub index ($$;$) {
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BEGIN { utf8::import() }
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return
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@_ == 2 ? CORE::index(@_[0], @_[1]) :
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CORE::index(@_[0], @_[1], @_[2]) ;
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}
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sub rindex ($$;$) {
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BEGIN { utf8::import() }
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return
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@_ == 2 ? CORE::rindex(@_[0], @_[1]) :
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CORE::rindex(@_[0], @_[1], @_[2]) ;
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}
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1;
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__END__
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=head1 NAME
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utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code
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=head1 SYNOPSIS
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use utf8;
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no utf8;
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# Convert a Perl scalar to/from UTF-8.
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$num_octets = utf8::upgrade($string);
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$success = utf8::downgrade($string[, FAIL_OK]);
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# Change the native bytes of a Perl scalar to/from UTF-8 bytes.
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utf8::encode($string);
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utf8::decode($string);
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$flag = utf8::valid(STRING);
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=head1 DESCRIPTION
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The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
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program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based
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platforms). The C<no utf8> pragma tells Perl to switch back to treating
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the source text as literal bytes in the current lexical scope.
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B<Do not use this pragma for anything else than telling Perl that your
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script is written in UTF-8.> The utility functions described below are
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directly usable without C<use utf8;>.
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Because it is not possible to reliably tell UTF-8 from native 8 bit
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encodings, you need either a Byte Order Mark at the beginning of your
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source code, or C<use utf8;>, to instruct perl.
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When UTF-8 becomes the standard source format, this pragma will
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effectively become a no-op. For convenience in what follows the term
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I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based
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platforms and UTF-EBCDIC on EBCDIC based platforms.
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See also the effects of the C<-C> switch and its cousin, the
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C<$ENV{PERL_UNICODE}>, in L<perlrun>.
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Enabling the C<utf8> pragma has the following effect:
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=over 4
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=item *
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Bytes in the source text that have their high-bit set will be treated
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as being part of a literal UTF-X sequence. This includes most
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literals such as identifier names, string constants, and constant
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regular expression patterns.
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On EBCDIC platforms characters in the Latin 1 character set are
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treated as being part of a literal UTF-EBCDIC character.
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=back
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Note that if you have bytes with the eighth bit on in your script
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(for example embedded Latin-1 in your string literals), C<use utf8>
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will be unhappy since the bytes are most probably not well-formed
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UTF-X. If you want to have such bytes under C<use utf8>, you can disable
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this pragma until the end the block (or file, if at top level) by
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C<no utf8;>.
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=head2 Utility functions
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The following functions are defined in the C<utf8::> package by the
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Perl core. You do not need to say C<use utf8> to use these and in fact
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you should not say that unless you really want to have UTF-8 source code.
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=over 4
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=item * $num_octets = utf8::upgrade($string)
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Converts in-place the internal octet sequence in the native encoding
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(Latin-1 or EBCDIC) to the equivalent character sequence in I<UTF-X>.
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I<$string> already encoded as characters does no harm. Returns the
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number of octets necessary to represent the string as I<UTF-X>. Can be
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used to make sure that the UTF-8 flag is on, so that C<\w> or C<lc()>
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work as Unicode on strings containing characters in the range 0x80-0xFF
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(on ASCII and derivatives).
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B<Note that this function does not handle arbitrary encodings.>
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Therefore Encode is recommended for the general purposes; see also
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L<Encode>.
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=item * $success = utf8::downgrade($string[, FAIL_OK])
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Converts in-place the internal octet sequence in I<UTF-X> to the
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equivalent octet sequence in the native encoding (Latin-1 or EBCDIC).
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I<$string> already encoded as native 8 bit does no harm. Can be used to
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make sure that the UTF-8 flag is off, e.g. when you want to make sure
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that the substr() or length() function works with the usually faster
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byte algorithm.
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Fails if the original I<UTF-X> sequence cannot be represented in the
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native 8 bit encoding. On failure dies or, if the value of C<FAIL_OK> is
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true, returns false.
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Returns true on success.
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B<Note that this function does not handle arbitrary encodings.>
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Therefore Encode is recommended for the general purposes; see also
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L<Encode>.
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=item * utf8::encode($string)
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Converts in-place the character sequence to the corresponding octet
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sequence in I<UTF-X>. The UTF8 flag is turned off, so that after this
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operation, the string is a byte string. Returns nothing.
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B<Note that this function does not handle arbitrary encodings.>
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Therefore Encode is recommended for the general purposes; see also
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L<Encode>.
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=item * $success = utf8::decode($string)
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Attempts to convert in-place the octet sequence in I<UTF-X> to the
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corresponding character sequence. The UTF-8 flag is turned on only if
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the source string contains multiple-byte I<UTF-X> characters. If
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I<$string> is invalid as I<UTF-X>, returns false; otherwise returns
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true.
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B<Note that this function does not handle arbitrary encodings.>
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Therefore Encode is recommended for the general purposes; see also
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L<Encode>.
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=item * $flag = utf8::valid(STRING)
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[INTERNAL] Will return true if the string is well-formed UTF-8.
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=back
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C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is
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cleared. See L<perlunicode> for more on the UTF8 flag and the C API
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functions C<sv_utf8_encode>,
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and C<sv_utf8_decode>, which are wrapped by the Perl functions
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C<utf8::encode> and
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C<utf8::decode>. Note that in the Perl 5.8.0 and 5.8.1 implementation
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the functions utf8::valid, utf8::encode, utf8::decode,
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utf8::upgrade, and utf8::downgrade are always available, without a
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C<require utf8> statement-- this may change in future releases.
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=head1 BUGS
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One can have Unicode in identifier names, but not in package/class or
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subroutine names. While some limited functionality towards this does
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exist as of Perl 5.8.0, that is more accidental than designed; use of
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Unicode for the said purposes is unsupported.
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One reason of this unfinishedness is its (currently) inherent
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unportability: since both package names and subroutine names may need
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to be mapped to file and directory names, the Unicode capability of
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the filesystem becomes important-- and there unfortunately aren't
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portable answers.
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=head1 SEE ALSO
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L<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode>
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=cut
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