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 ':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 EBCDICprint charnames::string_vianame("LATIN CAPITAL LETTER A"); # prints "A"Pragmause 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.
Thecharnames pragma supports arguments:full,:short, script names and customized aliases. If:full is present, for expansion of\N{CHARNAME}, the stringCHARNAME is first looked up in the list of standard Unicode character names. If:short is present, andCHARNAME has the formSCRIPT:CNAME, thenCNAME is looked up as a letter in scriptSCRIPT. Ifuse charnames is used with script name arguments, then for\N{CHARNAME} the nameCHARNAME 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 ofCHARNAME inside a given scriptSCRIPTNAME this pragma looks for the names
SCRIPTNAME CAPITAL LETTER CHARNAMESCRIPTNAME SMALL LETTER CHARNAMESCRIPTNAME LETTER CHARNAMEin the table of standard Unicode names. IfCHARNAME is lowercase, then theCAPITAL variant is ignored, otherwise theSMALL 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, usecharnames::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 ifuse 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).
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 FEEDFORM FEEDCARRIAGE RETURNNEXT LINELFFFCRNELAll the other standard abbreviations for the controls, such asACK forACKNOWLEDGE also can be used.
One can also use
BYTE ORDER MARKBOMand these abbreviations
Abbreviation Full NameCGJ COMBINING GRAPHEME JOINERFVS1 MONGOLIAN FREE VARIATION SELECTOR ONEFVS2 MONGOLIAN FREE VARIATION SELECTOR TWOFVS3 MONGOLIAN FREE VARIATION SELECTOR THREELRE LEFT-TO-RIGHT EMBEDDINGLRM LEFT-TO-RIGHT MARKLRO LEFT-TO-RIGHT OVERRIDEMMSP MEDIUM MATHEMATICAL SPACEMVS MONGOLIAN VOWEL SEPARATORNBSP NO-BREAK SPACENNBSP NARROW NO-BREAK SPACEPDF POP DIRECTIONAL FORMATTINGRLE RIGHT-TO-LEFT EMBEDDINGRLM RIGHT-TO-LEFT MARKRLO RIGHT-TO-LEFT OVERRIDESHY SOFT HYPHENVS1 VARIATION SELECTOR-1...VS256 VARIATION SELECTOR-256WJ WORD JOINERZWJ ZERO WIDTH JOINERZWNJ ZERO WIDTH NON-JOINERZWSP ZERO WIDTH SPACEFor backward compatibility one can use the old names for certain C0 and C1 controls
old newFILE SEPARATOR INFORMATION SEPARATOR FOURGROUP SEPARATOR INFORMATION SEPARATOR THREEHORIZONTAL TABULATION CHARACTER TABULATIONHORIZONTAL TABULATION SET CHARACTER TABULATION SETHORIZONTAL TABULATION WITH JUSTIFICATION CHARACTER TABULATION WITH JUSTIFICATIONPARTIAL LINE DOWN PARTIAL LINE FORWARDPARTIAL LINE UP PARTIAL LINE BACKWARDRECORD SEPARATOR INFORMATION SEPARATOR TWOREVERSE INDEX REVERSE LINE FEEDUNIT SEPARATOR INFORMATION SEPARATOR ONEVERTICAL TABULATION LINE TABULATIONVERTICAL TABULATION SET LINE TABULATION SETbut 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 characterEND OF PROTECTED AREA END OF GUARDED AREA, U+0097HIGH OCTET PRESET U+0081HOP U+0081IND U+0084INDEX U+0084PAD U+0080PADDING CHARACTER U+0080PRIVATE USE 1 PRIVATE USE ONE, U+0091PRIVATE USE 2 PRIVATE USE TWO, U+0092SGC U+0099SINGLE GRAPHIC CHARACTER INTRODUCER U+0099SINGLE-SHIFT 2 SINGLE SHIFT TWO, U+008ESINGLE-SHIFT 3 SINGLE SHIFT THREE, U+008FSTART OF PROTECTED AREA START OF GUARDED AREA, U+0096You 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 acustom translator (described below).
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 returnsundef if no name is known for the code point. In Unicode the proper name of these is the empty string, whichundef 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 getundef 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".
This is a runtime equivalent to\N{...}.name can be any expression that evaluates to a name accepted by\N{...} under the:full option tocharnames. In addition, any other options for the controlling"use charnames" in the same scope apply, like anyscript list,:short option, orcustom aliases you may have defined.
The only difference is that if the input name is unknown,string_vianame returnsundef instead of the REPLACEMENT CHARACTER and does not raise a warning message.
This is similar tostring_vianame. The main difference is that under most circumstances (see"BUGS" for the others), vianame returns an ordinal code point, whereasstring_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 theuse bytes pragma,
The mechanism of translation of\N{...} escapes is general and not hardwired intocharnames.pm. A module can install custom translations (inside the scope whichuses the module) with the following magic incantation:
sub import { shift; $^H{charnames} = \&translator;}Here translator() is a subroutine which takesCHARNAME 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 inbytes mode and out of it, the function should check the current state ofbytes-flag as in:
use bytes (); # for $bytes::hint_bitssub translator { if ($^H & $bytes::hint_bits) { return bytes_translator(@_); } else { return utf8_translator(@_); }}See"CUSTOM ALIASES" above for restrictions onCHARNAME.
Of course,vianame andviacode would need to be overridden as well.
vianame normally returns an ordinal code point, but when the input name is of the formU+..., it returns a chr instead. In this case, ifuse bytes is in effect and the character won't fit into a byte, it returnsundef 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 anyevals orrequires. This restriction should be lifted (but is low priority) in a future version of Perl.
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