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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 19:43:11 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 19:43:11 +0000
commitfc22b3d6507c6745911b9dfcc68f1e665ae13dbc (patch)
treece1e3bce06471410239a6f41282e328770aa404a /upstream/mageia-cauldron/man3pm/utf8.3pm
parentInitial commit. (diff)
downloadmanpages-l10n-fc22b3d6507c6745911b9dfcc68f1e665ae13dbc.tar.xz
manpages-l10n-fc22b3d6507c6745911b9dfcc68f1e665ae13dbc.zip
Adding upstream version 4.22.0.upstream/4.22.0
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+.\" -*- mode: troff; coding: utf-8 -*-
+.\" Automatically generated by Pod::Man 5.01 (Pod::Simple 3.43)
+.\"
+.\" Standard preamble:
+.\" ========================================================================
+.de Sp \" Vertical space (when we can't use .PP)
+.if t .sp .5v
+.if n .sp
+..
+.de Vb \" Begin verbatim text
+.ft CW
+.nf
+.ne \\$1
+..
+.de Ve \" End verbatim text
+.ft R
+.fi
+..
+.\" \*(C` and \*(C' are quotes in nroff, nothing in troff, for use with C<>.
+.ie n \{\
+. ds C` ""
+. ds C' ""
+'br\}
+.el\{\
+. ds C`
+. ds C'
+'br\}
+.\"
+.\" Escape single quotes in literal strings from groff's Unicode transform.
+.ie \n(.g .ds Aq \(aq
+.el .ds Aq '
+.\"
+.\" If the F register is >0, we'll generate index entries on stderr for
+.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
+.\" entries marked with X<> in POD. Of course, you'll have to process the
+.\" output yourself in some meaningful fashion.
+.\"
+.\" Avoid warning from groff about undefined register 'F'.
+.de IX
+..
+.nr rF 0
+.if \n(.g .if rF .nr rF 1
+.if (\n(rF:(\n(.g==0)) \{\
+. if \nF \{\
+. de IX
+. tm Index:\\$1\t\\n%\t"\\$2"
+..
+. if !\nF==2 \{\
+. nr % 0
+. nr F 2
+. \}
+. \}
+.\}
+.rr rF
+.\" ========================================================================
+.\"
+.IX Title "utf8 3pm"
+.TH utf8 3pm 2023-11-28 "perl v5.38.2" "Perl Programmers Reference Guide"
+.\" For nroff, turn off justification. Always turn off hyphenation; it makes
+.\" way too many mistakes in technical documents.
+.if n .ad l
+.nh
+.SH NAME
+utf8 \- Perl pragma to enable/disable UTF\-8 (or UTF\-EBCDIC) in source code
+.SH SYNOPSIS
+.IX Header "SYNOPSIS"
+.Vb 2
+\& 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); # "\ex{100}" becomes "\exc4\ex80"
+\& utf8::decode($string); # "\exc4\ex80" becomes "\ex{100}"
+\&
+\& # Convert a code point from the platform native character set to
+\& # Unicode, and vice\-versa.
+\& $unicode = utf8::native_to_unicode(ord(\*(AqA\*(Aq)); # returns 65 on both
+\& # ASCII and EBCDIC
+\& # platforms
+\& $native = utf8::unicode_to_native(65); # returns 65 on ASCII
+\& # platforms; 193 on
+\& # EBCDIC
+\&
+\& $flag = utf8::is_utf8($string); # since Perl 5.8.1
+\& $flag = utf8::valid($string);
+.Ve
+.SH DESCRIPTION
+.IX Header "DESCRIPTION"
+The \f(CW\*(C`use utf8\*(C'\fR pragma tells the Perl parser to allow UTF\-8 in the
+program text in the current lexical scope. The \f(CW\*(C`no utf8\*(C'\fR pragma tells Perl
+to switch back to treating the source text as literal bytes in the current
+lexical scope. (On EBCDIC platforms, technically it is allowing UTF-EBCDIC,
+and not UTF\-8, but this distinction is academic, so in this document the term
+UTF\-8 is used to mean both).
+.PP
+\&\fBDo not use this pragma for anything else than telling Perl that your
+script is written in UTF\-8.\fR The utility functions described below are
+directly usable without \f(CW\*(C`use utf8;\*(C'\fR.
+.PP
+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 \f(CW\*(C`use utf8;\*(C'\fR, to instruct perl.
+.PP
+When UTF\-8 becomes the standard source format, this pragma will
+effectively become a no-op.
+.PP
+See also the effects of the \f(CW\*(C`\-C\*(C'\fR switch and its cousin, the
+\&\f(CW\*(C`PERL_UNICODE\*(C'\fR environment variable, in perlrun.
+.PP
+Enabling the \f(CW\*(C`utf8\*(C'\fR pragma has the following effect:
+.IP \(bu 4
+Bytes in the source text that are not in the ASCII character set will be
+treated as being part of a literal UTF\-8 sequence. This includes most
+literals such as identifier names, string constants, and constant
+regular expression patterns.
+.PP
+Note that if you have non-ASCII, non\-UTF\-8 bytes in your script (for example
+embedded Latin\-1 in your string literals), \f(CW\*(C`use utf8\*(C'\fR will be unhappy. If
+you want to have such bytes under \f(CW\*(C`use utf8\*(C'\fR, you can disable this pragma
+until the end the block (or file, if at top level) by \f(CW\*(C`no utf8;\*(C'\fR.
+.SS "Utility functions"
+.IX Subsection "Utility functions"
+The following functions are defined in the \f(CW\*(C`utf8::\*(C'\fR package by the
+Perl core. You do not need to say \f(CW\*(C`use utf8\*(C'\fR to use these and in fact
+you should not say that unless you really want to have UTF\-8 source code.
+.IP \(bu 4
+\&\f(CW\*(C`$num_octets = utf8::upgrade($string)\*(C'\fR
+.Sp
+(Since Perl v5.8.0)
+Converts in-place the internal representation of the string from an octet
+sequence in the native encoding (Latin\-1 or EBCDIC) to UTF\-8. The
+logical character sequence itself is unchanged. If \fR\f(CI$string\fR\fI\fR is already
+upgraded, then this is a no-op. Returns the
+number of octets necessary to represent the string as UTF\-8.
+Since Perl v5.38, if \f(CW$string\fR is \f(CW\*(C`undef\*(C'\fR no action is taken; prior to that,
+it would be converted to be defined and zero-length.
+.Sp
+If your code needs to be compatible with versions of perl without
+\&\f(CW\*(C`use feature \*(Aqunicode_strings\*(Aq;\*(C'\fR, you can force Unicode semantics on
+a given string:
+.Sp
+.Vb 3
+\& # force unicode semantics for $string without the
+\& # "unicode_strings" feature
+\& utf8::upgrade($string);
+.Ve
+.Sp
+For example:
+.Sp
+.Vb 7
+\& # without explicit or implicit use feature \*(Aqunicode_strings\*(Aq
+\& my $x = "\exDF"; # LATIN SMALL LETTER SHARP S
+\& $x =~ /ss/i; # won\*(Aqt match
+\& my $y = uc($x); # won\*(Aqt convert
+\& utf8::upgrade($x);
+\& $x =~ /ss/i; # matches
+\& my $z = uc($x); # converts to "SS"
+.Ve
+.Sp
+\&\fBNote that this function does not handle arbitrary encodings\fR;
+use Encode instead.
+.IP \(bu 4
+\&\f(CW\*(C`$success = utf8::downgrade($string[, $fail_ok])\*(C'\fR
+.Sp
+(Since Perl v5.8.0)
+Converts in-place the internal representation of the string from UTF\-8 to the
+equivalent octet sequence in the native encoding (Latin\-1 or EBCDIC). The
+logical character sequence itself is unchanged. If \fR\f(CI$string\fR\fI\fR 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 \fBsubstr()\fR or
+\&\fBlength()\fR function works with the usually faster byte algorithm.
+.Sp
+Fails if the original UTF\-8 sequence cannot be represented in the
+native 8 bit encoding. On failure dies or, if the value of \fR\f(CI$fail_ok\fR\fI\fR is
+true, returns false.
+.Sp
+Returns true on success.
+.Sp
+If your code expects an octet sequence this can be used to validate
+that you've received one:
+.Sp
+.Vb 2
+\& # throw an exception if not representable as octets
+\& utf8::downgrade($string)
+\&
+\& # or do your own error handling
+\& utf8::downgrade($string, 1) or die "string must be octets";
+.Ve
+.Sp
+\&\fBNote that this function does not handle arbitrary encodings\fR;
+use Encode instead.
+.IP \(bu 4
+\&\f(CWutf8::encode($string)\fR
+.Sp
+(Since Perl v5.8.0)
+Converts in-place the character sequence to the corresponding octet
+sequence in Perl's extended UTF\-8. That is, every (possibly wide) character
+gets replaced with a sequence of one or more characters that represent the
+individual UTF\-8 bytes of the character. The UTF8 flag is turned off.
+Returns nothing.
+.Sp
+.Vb 4
+\& my $x = "\ex{100}"; # $x contains one character, with ord 0x100
+\& utf8::encode($x); # $x contains two characters, with ords (on
+\& # ASCII platforms) 0xc4 and 0x80. On EBCDIC
+\& # 1047, this would instead be 0x8C and 0x41.
+.Ve
+.Sp
+Similar to:
+.Sp
+.Vb 2
+\& use Encode;
+\& $x = Encode::encode("utf8", $x);
+.Ve
+.Sp
+\&\fBNote that this function does not handle arbitrary encodings\fR;
+use Encode instead.
+.IP \(bu 4
+\&\f(CW\*(C`$success = utf8::decode($string)\*(C'\fR
+.Sp
+(Since Perl v5.8.0)
+Attempts to convert in-place the octet sequence encoded in Perl's extended
+UTF\-8 to the corresponding character sequence. That is, it replaces each
+sequence of characters in the string whose ords represent a valid (extended)
+UTF\-8 byte sequence, with the corresponding single character. The UTF\-8 flag
+is turned on only if the source string contains multiple-byte UTF\-8
+characters. If \fR\f(CI$string\fR\fI\fR is invalid as extended UTF\-8, returns false;
+otherwise returns true.
+.Sp
+.Vb 11
+\& my $x = "\exc4\ex80"; # $x contains two characters, with ords
+\& # 0xc4 and 0x80
+\& utf8::decode($x); # On ASCII platforms, $x contains one char,
+\& # with ord 0x100. Since these bytes aren\*(Aqt
+\& # legal UTF\-EBCDIC, on EBCDIC platforms, $x is
+\& # unchanged and the function returns FALSE.
+\& my $y = "\exc3\ex83\exc2\exab"; This has been encoded twice; this
+\& # example is only for ASCII platforms
+\& utf8::decode($y); # Converts $y to \exc3\exab, returns TRUE;
+\& utf8::decode($y); # Further converts to \exeb, returns TRUE;
+\& utf8::decode($y); # Returns FALSE, leaves $y unchanged
+.Ve
+.Sp
+\&\fBNote that this function does not handle arbitrary encodings\fR;
+use Encode instead.
+.IP \(bu 4
+\&\f(CW\*(C`$unicode = utf8::native_to_unicode($code_point)\*(C'\fR
+.Sp
+(Since Perl v5.8.0)
+This takes an unsigned integer (which represents the ordinal number of a
+character (or a code point) on the platform the program is being run on) and
+returns its Unicode equivalent value. Since ASCII platforms natively use the
+Unicode code points, this function returns its input on them. On EBCDIC
+platforms it converts from EBCDIC to Unicode.
+.Sp
+A meaningless value will currently be returned if the input is not an unsigned
+integer.
+.Sp
+Since Perl v5.22.0, calls to this function are optimized out on ASCII
+platforms, so there is no performance hit in using it there.
+.IP \(bu 4
+\&\f(CW\*(C`$native = utf8::unicode_to_native($code_point)\*(C'\fR
+.Sp
+(Since Perl v5.8.0)
+This is the inverse of \f(CWutf8::native_to_unicode()\fR, converting the other
+direction. Again, on ASCII platforms, this returns its input, but on EBCDIC
+platforms it will find the native platform code point, given any Unicode one.
+.Sp
+A meaningless value will currently be returned if the input is not an unsigned
+integer.
+.Sp
+Since Perl v5.22.0, calls to this function are optimized out on ASCII
+platforms, so there is no performance hit in using it there.
+.IP \(bu 4
+\&\f(CW\*(C`$flag = utf8::is_utf8($string)\*(C'\fR
+.Sp
+(Since Perl 5.8.1) Test whether \fR\f(CI$string\fR\fI\fR is marked internally as encoded in
+UTF\-8. Functionally the same as \f(CWEncode::is_utf8($string)\fR.
+.Sp
+Typically only necessary for debugging and testing, if you need to
+dump the internals of an SV, Devel::Peek's \fBDump()\fR
+provides more detail in a compact form.
+.Sp
+If you still think you need this outside of debugging, testing or
+dealing with filenames, you should probably read perlunitut and
+"What is "the UTF8 flag"?" in perlunifaq.
+.Sp
+Don't use this flag as a marker to distinguish character and binary
+data: that should be decided for each variable when you write your
+code.
+.Sp
+To force unicode semantics in code portable to perl 5.8 and 5.10, call
+\&\f(CWutf8::upgrade($string)\fR unconditionally.
+.IP \(bu 4
+\&\f(CW\*(C`$flag = utf8::valid($string)\*(C'\fR
+.Sp
+[INTERNAL] Test whether \fR\f(CI$string\fR\fI\fR is in a consistent state regarding
+UTF\-8. Will return true if it is well-formed Perl extended UTF\-8 and has the
+UTF\-8 flag
+on \fBor\fR if \fI\fR\f(CI$string\fR\fI\fR is held as bytes (both these states are 'consistent').
+The main reason for this routine is to allow Perl's test suite to check
+that operations have left strings in a consistent state.
+.PP
+\&\f(CW\*(C`utf8::encode\*(C'\fR is like \f(CW\*(C`utf8::upgrade\*(C'\fR, but the UTF8 flag is
+cleared. See perlunicode, and the C API
+functions \f(CW\*(C`sv_utf8_upgrade\*(C'\fR,
+\&\f(CW\*(C`"sv_utf8_downgrade" in perlapi\*(C'\fR, \f(CW\*(C`"sv_utf8_encode" in perlapi\*(C'\fR,
+and \f(CW\*(C`"sv_utf8_decode" in perlapi\*(C'\fR, which are wrapped by the Perl functions
+\&\f(CW\*(C`utf8::upgrade\*(C'\fR, \f(CW\*(C`utf8::downgrade\*(C'\fR, \f(CW\*(C`utf8::encode\*(C'\fR and
+\&\f(CW\*(C`utf8::decode\*(C'\fR. Also, the functions \f(CW\*(C`utf8::is_utf8\*(C'\fR, \f(CW\*(C`utf8::valid\*(C'\fR,
+\&\f(CW\*(C`utf8::encode\*(C'\fR, \f(CW\*(C`utf8::decode\*(C'\fR, \f(CW\*(C`utf8::upgrade\*(C'\fR, and \f(CW\*(C`utf8::downgrade\*(C'\fR are
+actually internal, and thus always available, without a \f(CW\*(C`require utf8\*(C'\fR
+statement.
+.SH BUGS
+.IX Header "BUGS"
+Some filesystems may not support UTF\-8 file names, or they may be supported
+incompatibly with Perl. Therefore UTF\-8 names that are visible to the
+filesystem, such as module names may not work.
+.SH "SEE ALSO"
+.IX Header "SEE ALSO"
+perlunitut, perluniintro, perlrun, bytes, perlunicode