| charnames - define character names for C<\N{named}> string literal escapes |
charnames - define character names for \N{named} string literal escapes
use charnames ':full';
print "\N{GREEK SMALL LETTER SIGMA} is called sigma.\n";
use charnames ':short';
print "\N{greek:Sigma} is an upper-case sigma.\n";
use charnames qw(cyrillic greek);
print "\N{sigma} is Greek sigma, and \N{be} is Cyrillic b.\n";
use charnames ":full", ":alias" => {
e_ACUTE => "LATIN SMALL LETTER E WITH ACUTE",
};
print "\N{e_ACUTE} is a small letter e with an acute.\n";
use charnames ();
print charnames::viacode(0x1234); # prints "ETHIOPIC SYLLABLE SEE"
printf "%04X", charnames::vianame("GOTHIC LETTER AHSA"); # prints "10330"
Pragma use charnames supports arguments :full, :short, script
names and customized aliases. If :full is present, for expansion of
\N{CHARNAME}, the string CHARNAME is first looked up in the list of
standard Unicode character names. If :short is present, and
CHARNAME has the form SCRIPT:CNAME, then CNAME is looked up
as a letter in script SCRIPT. If pragma use charnames is used
with script name arguments, then for \N{CHARNAME} the name
CHARNAME is looked up as a letter in the given scripts (in the
specified order). Customized aliases are explained in CUSTOM ALIASES.
For lookup of CHARNAME inside a given script SCRIPTNAME
this pragma looks for the names
SCRIPTNAME CAPITAL LETTER CHARNAME SCRIPTNAME SMALL LETTER CHARNAME SCRIPTNAME LETTER CHARNAME
in the table of standard Unicode names. If CHARNAME is lowercase,
then the CAPITAL variant is ignored, otherwise the SMALL variant
is ignored.
Note that \N{...} is compile-time, it's a special form of string
constant used inside double-quoted strings: in other words, you cannot
use variables inside the \N{...}. If you want similar run-time
functionality, use charnames::vianame().
For the C0 and C1 control characters (U+0000..U+001F, U+0080..U+009F) as of Unicode 3.1, there are no official Unicode names but you can use instead the ISO 6429 names (LINE FEED, ESCAPE, and so forth). In Unicode 3.2 (as of Perl 5.8) some naming changes take place ISO 6429 has been updated, see ALIASES. Also note that the U+UU80, U+0081, U+0084, and U+0099 do not have names even in ISO 6429.
Since the Unicode standard uses ``U+HHHH'', so can you: ``\N{U+263a}'' is the Unicode smiley face, or ``\N{WHITE SMILING FACE}''.
The mechanism of translation of \N{...} escapes is general and not
hardwired into charnames.pm. A module can install custom
translations (inside the scope which uses the module) with the
following magic incantation:
use charnames (); # for $charnames::hint_bits
sub import {
shift;
$^H |= $charnames::hint_bits;
$^H{charnames} = \&translator;
}
Here translator() is a subroutine which takes CHARNAME as an
argument, and returns text to insert into the string instead of the
\N{CHARNAME} escape. Since the text to insert should be different
in bytes mode and out of it, the function should check the current
state of bytes-flag as in:
use bytes (); # for $bytes::hint_bits
sub translator {
if ($^H & $bytes::hint_bits) {
return bytes_translator(@_);
}
else {
return utf8_translator(@_);
}
}
This version of charnames supports three mechanisms of adding local or customized aliases to standard Unicode naming conventions (:full)
use charnames ":full", ":alias" => {
e_ACUTE => "LATIN SMALL LETTER E WITH ACUTE",
};
my $str = "\N{e_ACUTE}";
use charnames ":full", ":alias" => "pro";
will try to read "unicore/pro_alias.pl" from the @INC path. This
file should return a list in plain perl:
(
A_GRAVE => "LATIN CAPITAL LETTER A WITH GRAVE",
A_CIRCUM => "LATIN CAPITAL LETTER A WITH CIRCUMFLEX",
A_DIAERES => "LATIN CAPITAL LETTER A WITH DIAERESIS",
A_TILDE => "LATIN CAPITAL LETTER A WITH TILDE",
A_BREVE => "LATIN CAPITAL LETTER A WITH BREVE",
A_RING => "LATIN CAPITAL LETTER A WITH RING ABOVE",
A_MACRON => "LATIN CAPITAL LETTER A WITH MACRON",
);
use charnames ":alias" => ":pro";
works exactly the same as the alias pairs, only this time,
":full" is inserted automatically as first argument (if no
other argument is given).
Returns the full name of the character indicated by the numeric code. The example
print charnames::viacode(0x2722);
prints ``FOUR TEARDROP-SPOKED ASTERISK''.
Returns undef if no name is known for the code.
This works only for the standard names, and does not yet apply to custom translators.
Notice that the name returned for of U+FEFF is ``ZERO WIDTH NO-BREAK SPACE'', not ``BYTE ORDER MARK''.
Returns the code point indicated by the name. The example
printf "%04X", charnames::vianame("FOUR TEARDROP-SPOKED ASTERISK");
prints ``2722''.
Returns undef if the name is unknown.
This works only for the standard names, and does not yet apply to custom translators.
A few aliases have been defined for convenience: instead of having to use the official names
LINE FEED (LF)
FORM FEED (FF)
CARRIAGE RETURN (CR)
NEXT LINE (NEL)
(yes, with parentheses) one can use
LINE FEED
FORM FEED
CARRIAGE RETURN
NEXT LINE
LF
FF
CR
NEL
One can also use
BYTE ORDER MARK
BOM
and
ZWNJ
ZWJ
for ZERO WIDTH NON-JOINER and ZERO WIDTH JOINER.
For backward compatibility one can use the old names for certain C0 and C1 controls
old new
HORIZONTAL TABULATION CHARACTER TABULATION
VERTICAL TABULATION LINE TABULATION
FILE SEPARATOR INFORMATION SEPARATOR FOUR
GROUP SEPARATOR INFORMATION SEPARATOR THREE
RECORD SEPARATOR INFORMATION SEPARATOR TWO
UNIT SEPARATOR INFORMATION SEPARATOR ONE
PARTIAL LINE DOWN PARTIAL LINE FORWARD
PARTIAL LINE UP PARTIAL LINE BACKWARD
but the old names in addition to giving the character will also give a warning about being deprecated.
If you ask by name for a character that does not exist, a warning is given and the Unicode replacement character ``\x{FFFD}'' is returned.
If you ask by code for a character that does not exist, no warning is
given and undef is returned. (Though if you ask for a code point
past U+10FFFF you do get a warning.)
Since evaluation of the translation function happens in a middle of
compilation (of a string literal), the translation function should not
do any evals or requires. This restriction should be lifted in
a future version of Perl.
| charnames - define character names for C<\N{named}> string literal escapes |