| charnames - access to Unicode character names and named character sequences; also define character names |
charnames - access to Unicode character names and named character sequences; also define character names
use charnames ':full';
print "\N{GREEK SMALL LETTER SIGMA} is called sigma.\n";
print "\N{LATIN CAPITAL LETTER E WITH VERTICAL LINE BELOW}",
" is an officially named sequence of two Unicode characters\n";
use charnames ':loose';
print "\N{Greek small-letter sigma}",
"can be used to ignore case, underscores, most blanks,"
"and when you aren't sure if the official name has hyphens\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 utf8;
use charnames ":full", ":alias" => {
e_ACUTE => "LATIN SMALL LETTER E WITH ACUTE",
mychar => 0xE8000, # Private use area
"自転車に乗る人" => "BICYCLIST"
};
print "\N{e_ACUTE} is a small letter e with an acute.\n";
print "\N{mychar} allows me to name private use characters.\n";
print "And I can create synonyms in other languages,",
" such as \N{自転車に乗る人} for "BICYCLIST (U+1F6B4)\n";
use charnames ();
print charnames::viacode(0x1234); # prints "ETHIOPIC SYLLABLE SEE"
printf "%04X", charnames::vianame("GOTHIC LETTER AHSA"); # prints
# "10330"
print charnames::vianame("LATIN CAPITAL LETTER A"); # prints 65 on
# ASCII platforms;
# 193 on EBCDIC
print charnames::string_vianame("LATIN CAPITAL LETTER A"); # prints "A"
Pragma use charnames is used to gain access to the names of the
Unicode characters and named character sequences, and to allow you to define
your own character and character sequence names.
All forms of the pragma enable use of the following 3 functions:
Starting in Perl v5.16, any occurrence of \N{CHARNAME} sequences
in a double-quotish string automatically loads this module with arguments
:full and :short (described below) if it hasn't already been loaded with
different arguments, in order to compile the named Unicode character into
position in the string. Prior to v5.16, an explicit use charnames was
required to enable this usage. (However, prior to v5.16, the form "use
charnames ();"> did not enable \N{CHARNAME}.)
Note that \N{U+...}, where the ... is a hexadecimal number,
also inserts a character into a string.
The character it inserts is the one whose Unicode code point
(ordinal value) is equal to the number. For example, "\N{U+263a}" is
the Unicode (white background, black foreground) smiley face
equivalent to "\N{WHITE SMILING FACE}".
Also note, \N{...} can mean a regex quantifier instead of a character
name, when the ... is a number (or comma separated pair of numbers
(see QUANTIFIERS in the perlreref manpage), and is not related to this pragma.
The charnames pragma supports arguments :full, :loose, :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.
:loose is a variant of :full which allows CHARNAME to be less
precisely specified. Details are in LOOSE MATCHES.
If :short is present, and
CHARNAME has the form SCRIPT:CNAME, then CNAME is looked up
as a letter in script SCRIPT, as described in the next paragraph.
Or, if 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 can override these, and are explained in
CUSTOM ALIASES.
For lookup of CHARNAME inside a given script SCRIPTNAME, this pragma looks in the table of standard Unicode names for the names
SCRIPTNAME CAPITAL LETTER CHARNAME SCRIPTNAME SMALL LETTER CHARNAME SCRIPTNAME LETTER CHARNAME
If CHARNAME is all lowercase,
then the CAPITAL variant is ignored, otherwise the SMALL variant
is ignored, and both CHARNAME and SCRIPTNAME are converted to all
uppercase for look-up. Other than that, both of them follow loose rules if :loose is also specified; strict otherwise.
Note that \N{...} is compile-time; it's a special form of string
constant used inside double-quotish strings; this means that you cannot
use variables inside the \N{...}. If you want similar run-time
functionality, use
charnames::string_vianame().
Note, starting in Perl 5.18, the name BELL refers to the Unicode character
U+1F514, instead of the traditional U+0007. For the latter, use ALERT
or BEL.
It is a syntax error to use \N{NAME} where NAME is unknown.
For \N{NAME}, it is a fatal error if use bytes is in effect and the
input name is that of a character that won't fit into a byte (i.e., whose
ordinal is above 255).
Otherwise, any string that includes a \N{charname} or
\N{U+code point} will automatically have Unicode rules (see
Byte and Character Semantics in the perlunicode manpage).
By specifying :loose, Unicode's loose character name matching rules are
selected instead of the strict exact match used otherwise.
That means that CHARNAME doesn't have to be so precisely specified.
Upper/lower case doesn't matter (except with scripts as mentioned above), nor
do any underscores, and the only hyphens that matter are those at the
beginning or end of a word in the name (with one exception: the hyphen in
U+1180 HANGUL JUNGSEONG O-E does matter).
Also, blanks not adjacent to hyphens don't matter.
The official Unicode names are quite variable as to where they use hyphens
versus spaces to separate word-like units, and this option allows you to not
have to care as much.
The reason non-medial hyphens matter is because of cases like
U+0F60 TIBETAN LETTER -A versus U+0F68 TIBETAN LETTER A.
The hyphen here is significant, as is the space before it, and so both must be
included.
:loose slows down look-ups by a factor of 2 to 3 versus
:full, but the trade-off may be worth it to you. Each individual look-up
takes very little time, and the results are cached, so the speed difference
would become a factor only in programs that do look-ups of many different
spellings, and probably only when those look-ups are through vianame() and
string_vianame(), since \N{...} look-ups are done at compile time.
Starting in Unicode 6.1 and Perl v5.16, Unicode defines many abbreviations and names that were formerly Perl extensions, and some additional ones that Perl did not previously accept. The list is getting too long to reproduce here, but you can get the complete list from the Unicode web site: http://www.unicode.org/Public/UNIDATA/NameAliases.txt.
Earlier versions of Perl accepted almost all the 6.1 names. These were most extensively documented in the v5.14 version of this pod: http://perldoc.perl.org/5.14.0/charnames.html#ALIASES.
You can add customized aliases to standard (:full) Unicode naming
conventions. The aliases override any standard definitions, so, if
you're twisted enough, you can change "\N{LATIN CAPITAL LETTER A}" to
mean "B", etc.
Aliases must begin with a character that is alphabetic. After that, each may
contain any combination of word (\w) characters, SPACE (U+0020),
HYPHEN-MINUS (U+002D), LEFT PARENTHESIS (U+0028), and RIGHT PARENTHESIS
(U+0029). These last two should never have been allowed
in names, and are retained for backwards compatibility only, and may be
deprecated and removed in future releases of Perl, so don't use them for new
names. (More precisely, the first character of a name you specify must be
something that matches all of \p{ID_Start}, \p{Alphabetic}, and
\p{Gc=Letter}. This makes sure it is what any reasonable person would view
as an alphabetic character. And, the continuation characters that match \w
must also match \p{ID_Continue}.) Starting with Perl v5.18, any Unicode
characters meeting the above criteria may be used; prior to that only
Latin1-range characters were acceptable.
An alias can map to either an official Unicode character name (not a loose
matched name) or to a
numeric code point (ordinal). The latter is useful for assigning names
to code points in Unicode private use areas such as U+E800 through
U+F8FF.
A numeric code point must be a non-negative integer, or a string beginning
with "U+" or "0x" with the remainder considered to be a
hexadecimal integer. A literal numeric constant must be unsigned; it
will be interpreted as hex if it has a leading zero or contains
non-decimal hex digits; otherwise it will be interpreted as decimal.
If it begins with "U+", it is interpreted as the Unicode code point;
otherwise it is interpreted as native. (Only code points below 256 can
differ between Unicode and native.) Thus U+41 is always the Latin letter
``A''; but 0x41 can be ``NO-BREAK SPACE'' on EBCDIC platforms.
Aliases are added either by the use of anonymous hashes:
use charnames ":alias" => {
e_ACUTE => "LATIN SMALL LETTER E WITH ACUTE",
mychar1 => 0xE8000,
};
my $str = "\N{e_ACUTE}";
or by using a file containing aliases:
use charnames ":alias" => "pro";
This will try to read "unicore/pro_alias.pl" from the @INC path. This
file should return a list in plain perl:
(
A_GRAVE => "LATIN CAPITAL LETTER A WITH GRAVE",
A_CIRCUM => "LATIN CAPITAL LETTER A WITH CIRCUMFLEX",
A_DIAERES => "LATIN CAPITAL LETTER A WITH DIAERESIS",
A_TILDE => "LATIN CAPITAL LETTER A WITH TILDE",
A_BREVE => "LATIN CAPITAL LETTER A WITH BREVE",
A_RING => "LATIN CAPITAL LETTER A WITH RING ABOVE",
A_MACRON => "LATIN CAPITAL LETTER A WITH MACRON",
mychar2 => "U+E8001",
);
Both these methods insert ":full" automatically as the first argument (if no
other argument is given), and you can give the ":full" explicitly as
well, like
use charnames ":full", ":alias" => "pro";
":loose" has no effect with these. Input names must match exactly, using
":full" rules.
Also, both these methods currently allow only single characters to be named. To name a sequence of characters, use a custom translator (described below).
This is a runtime equivalent to \N{...}. name can be any expression
that evaluates to a name accepted by \N{...} under the :full option to charnames. In addition, any other options for the
controlling "use charnames" in the same scope apply, like :loose or any
script list, :short option, or custom aliases you may have defined.
The only differences are due to the fact that string_vianame is run-time
and \N{} is compile time. You can't interpolate inside a \N{}, (so
\N{$variable} doesn't work); and if the input name is unknown,
string_vianame returns undef instead of it being a syntax error.
This is similar to string_vianame. The main difference is that under most
circumstances, vianame returns an ordinal code
point, whereas string_vianame returns a string. For example,
printf "U+%04X", charnames::vianame("FOUR TEARDROP-SPOKED ASTERISK");
prints ``U+2722''.
This leads to the other two differences. Since a single code point is
returned, the function can't handle named character sequences, as these are
composed of multiple characters (it returns undef for these. And, the code
point can be that of any
character, even ones that aren't legal under the use bytes pragma,
See BUGS for the circumstances in which the behavior differs from that described above.
Returns the full name of the character indicated by the numeric code. For example,
print charnames::viacode(0x2722);
prints ``FOUR TEARDROP-SPOKED ASTERISK''.
The name returned is the ``best'' (defined below) official name or alias
for the code point, if
available; otherwise your custom alias for it, if defined; otherwise undef.
This means that your alias will only be returned for code points that don't
have an official Unicode name (nor alias) such as private use code points.
If you define more than one name for the code point, it is indeterminate which one will be returned.
As mentioned, the function returns undef if no name is known for the code
point. In Unicode the proper name for these is the empty string, which
undef stringifies to. (If you ask for a code point past the legal
Unicode maximum of U+10FFFF that you haven't assigned an alias to, you
get undef plus a warning.)
The input number must be a non-negative integer, or a string beginning
with "U+" or "0x" with the remainder considered to be a
hexadecimal integer. A literal numeric constant must be unsigned; it
will be interpreted as hex if it has a leading zero or contains
non-decimal hex digits; otherwise it will be interpreted as decimal.
If it begins with "U+", it is interpreted as the Unicode code point;
otherwise it is interpreted as native. (Only code points below 256 can
differ between Unicode and native.) Thus U+41 is always the Latin letter
``A''; but 0x41 can be ``NO-BREAK SPACE'' on EBCDIC platforms.
As mentioned above under ALIASES, Unicode 6.1 defines extra names
(synonyms or aliases) for some code points, most of which were already
available as Perl extensions. All these are accepted by \N{...} and the
other functions in this module, but viacode has to choose which one
name to return for a given input code point, so it returns the ``best'' name.
To understand how this works, it is helpful to know more about the Unicode
name properties. All code points actually have only a single name, which
(starting in Unicode 2.0) can never change once a character has been assigned
to the code point. But mistakes have been made in assigning names, for
example sometimes a clerical error was made during the publishing of the
Standard which caused words to be misspelled, and there was no way to correct
those. The Name_Alias property was eventually created to handle these
situations. If a name was wrong, a corrected synonym would be published for
it, using Name_Alias. viacode will return that corrected synonym as the
``best'' name for a code point. (It is even possible, though it hasn't happened
yet, that the correction itself will need to be corrected, and so another
Name_Alias can be created for that code point; viacode will return the
most recent correction.)
The Unicode name for each of the control characters (such as LINE FEED) is the
empty string. However almost all had names assigned by other standards, such
as the ASCII Standard, or were in common use. viacode returns these names
as the ``best'' ones available. Unicode 6.1 has created Name_Aliases for each
of them, including alternate names, like NEW LINE. viacode uses the
original name, ``LINE FEED'' in preference to the alternate. Similarly the
name returned for U+FEFF is ``ZERO WIDTH NO-BREAK SPACE'', not ``BYTE ORDER
MARK''.
Until Unicode 6.1, the 4 control characters U+0080, U+0081, U+0084, and U+0099 did not have names nor aliases. To preserve backwards compatibility, any alias you define for these code points will be returned by this function, in preference to the official name.
Some code points also have abbreviated names, such as ``LF'' or ``NL''.
viacode never returns these.
Because a name correction may be added in future Unicode releases, the name
that viacode returns may change as a result. This is a rare event, but it
does happen.
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:
sub import {
shift;
$^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.
This is the only way you can create a custom named sequence of code points.
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(@_);
}
}
See CUSTOM ALIASES above for restrictions on CHARNAME.
Of course, vianame, viacode, and string_vianame would need to be
overridden as well.
vianame() normally returns an ordinal code point, but when the input name is of
the form U+..., it returns a chr instead. In this case, if use bytes is
in effect and the character won't fit into a byte, it returns undef and
raises a warning.
Since evaluation of the translation function (see CUSTOM TRANSLATORS) happens in the middle of compilation (of a string
literal), the translation function should not do any evals or
requires. This restriction should be lifted (but is low priority) in
a future version of Perl.
| charnames - access to Unicode character names and named character sequences; also define character names |