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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.