NAME¶
charnames - access to Unicode character names and named character sequences;
also define character names
SYNOPSIS¶
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 ':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",
mychar => 0xE8000, # Private use area
};
print "\N{e_ACUTE} is a small letter e with an acute.\n";
print "\\N{mychar} allows me to name private use characters.\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"
DESCRIPTION¶
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:
- •
- "charnames::string_vianame(name)" for
run-time lookup of a either a character name or a named character
sequence, returning its string representation
- •
- "charnames::vianame(name)" for run-time
lookup of a character name (but not a named character sequence) to get its
ordinal value (code point)
- •
- "charnames::viacode(code)" for run-time
lookup of a code point to get its Unicode name.
All forms other than "use charnames ();" also enable the use
of "\N{
CHARNAME}" sequences to compile a Unicode character
into a string, based on its name.
Note that "\N{U+
...}", where the
... is a hexadecimal
number, also inserts a character into a string, but doesn't require the use of
this pragma. The character it inserts is the one whose code point (ordinal
value) is equal to the number. For example, "\N{U+263a}" is the
Unicode (white background, black foreground) smiley face; it doesn't require
this pragma, whereas the equivalent, "\N{WHITE SMILING FACE}" does.
Also, "\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 perlreref), and is not related to this
pragma.
The "charnames" pragma 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 "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 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-quotish strings; this means that you cannot use
variables inside the "\N{...}". If you want similar run-time
functionality, use
charnames::string_vianame().
For the C0 and C1 control characters (U+0000..U+001F, U+0080..U+009F) there are
no official Unicode names but you can use instead the ISO 6429 names (LINE
FEED, ESCAPE, and so forth, and their abbreviations, LF, ESC, ...). In Unicode
3.2 (as of Perl 5.8) some naming changes took place, and ISO 6429 was updated,
see "ALIASES".
If the input name is unknown, "\N{NAME}" raises a warning and
substitutes the Unicode REPLACEMENT CHARACTER (U+FFFD).
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
semantics (see "Byte and Character Semantics" in perlunicode).
ALIASES¶
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
All the other standard abbreviations for the controls, such as "ACK"
for "ACKNOWLEDGE" also can be used.
One can also use
BYTE ORDER MARK
BOM
and these abbreviations
Abbreviation Full Name
CGJ COMBINING GRAPHEME JOINER
FVS1 MONGOLIAN FREE VARIATION SELECTOR ONE
FVS2 MONGOLIAN FREE VARIATION SELECTOR TWO
FVS3 MONGOLIAN FREE VARIATION SELECTOR THREE
LRE LEFT-TO-RIGHT EMBEDDING
LRM LEFT-TO-RIGHT MARK
LRO LEFT-TO-RIGHT OVERRIDE
MMSP MEDIUM MATHEMATICAL SPACE
MVS MONGOLIAN VOWEL SEPARATOR
NBSP NO-BREAK SPACE
NNBSP NARROW NO-BREAK SPACE
PDF POP DIRECTIONAL FORMATTING
RLE RIGHT-TO-LEFT EMBEDDING
RLM RIGHT-TO-LEFT MARK
RLO RIGHT-TO-LEFT OVERRIDE
SHY SOFT HYPHEN
VS1 VARIATION SELECTOR-1
.
.
.
VS256 VARIATION SELECTOR-256
WJ WORD JOINER
ZWJ ZERO WIDTH JOINER
ZWNJ ZERO WIDTH NON-JOINER
ZWSP ZERO WIDTH SPACE
For backward compatibility one can use the old names for certain C0 and C1
controls
old new
FILE SEPARATOR INFORMATION SEPARATOR FOUR
GROUP SEPARATOR INFORMATION SEPARATOR THREE
HORIZONTAL TABULATION CHARACTER TABULATION
HORIZONTAL TABULATION SET CHARACTER TABULATION SET
HORIZONTAL TABULATION WITH JUSTIFICATION CHARACTER TABULATION
WITH JUSTIFICATION
PARTIAL LINE DOWN PARTIAL LINE FORWARD
PARTIAL LINE UP PARTIAL LINE BACKWARD
RECORD SEPARATOR INFORMATION SEPARATOR TWO
REVERSE INDEX REVERSE LINE FEED
UNIT SEPARATOR INFORMATION SEPARATOR ONE
VERTICAL TABULATION LINE TABULATION
VERTICAL TABULATION SET LINE TABULATION SET
but the old names in addition to giving the character will also give a warning
about being deprecated.
And finally, certain published variants are usable, including some for controls
that have no Unicode names:
name character
END OF PROTECTED AREA END OF GUARDED AREA, U+0097
HIGH OCTET PRESET U+0081
HOP U+0081
IND U+0084
INDEX U+0084
PAD U+0080
PADDING CHARACTER U+0080
PRIVATE USE 1 PRIVATE USE ONE, U+0091
PRIVATE USE 2 PRIVATE USE TWO, U+0092
SGC U+0099
SINGLE GRAPHIC CHARACTER INTRODUCER U+0099
SINGLE-SHIFT 2 SINGLE SHIFT TWO, U+008E
SINGLE-SHIFT 3 SINGLE SHIFT THREE, U+008F
START OF PROTECTED AREA START OF GUARDED AREA, U+0096
CUSTOM 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.
Note that an alias should not be something that is a legal curly brace-enclosed
quantifier (see "QUANTIFIERS" in perlreref). For example
"\N{123}" means to match 123 non-newline characters, and is not
treated as a charnames alias. Aliases are discouraged from beginning with
anything other than an alphabetic character and from containing anything other
than alphanumerics, spaces, dashes, parentheses, and underscores. Currently
they must be ASCII.
An alias can map to either an official Unicode character 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.
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";
Also, both these methods currently allow only a single character to be named. To
name a sequence of characters, use a custom translator (described below).
charnames::viacode(code)¶
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 official name for the code point, if available;
otherwise your custom alias for it. This means that your alias will only be
returned for code points that don't have an official Unicode name (nor Unicode
version 1 name), such as private use code points, and the 4 control characters
U+0080, U+0081, U+0084, and U+0099. If you define more than one name for the
code point, it is indeterminate which one will be returned.
The function returns "undef" if no name is known for the code point.
In Unicode the proper name of 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.
Notice that the name returned for of U+FEFF is "ZERO WIDTH NO-BREAK
SPACE", not "BYTE ORDER MARK".
charnames::string_vianame(name)¶
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 any script list, ":short" option, or custom aliases you may
have defined.
The only difference is that if the input name is unknown,
"string_vianame" returns "undef" instead of the
REPLACEMENT CHARACTER and does not raise a warning message.
charnames::vianame(name)¶
This is similar to "string_vianame". The main difference is that under
most circumstances (see "BUGS" for the others), 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. And, the code point can be that of any character, even
ones that aren't legal under the "use bytes" pragma,
CUSTOM TRANSLATORS¶
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 "use"s 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. 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" and "viacode" would need to be
overridden as well.
BUGS¶
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.
Names must be ASCII characters only, which means that you are out of luck if you
want to create aliases in a language where some or all the characters of the
desired aliases are non-ASCII.
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 "eval"s or
"require"s. This restriction should be lifted (but is low priority)
in a future version of Perl.