package charnames;
use strict;
use warnings;
use File::Spec;
our $VERSION = '1.23';

use bytes ();          # for $bytes::hint_bits

# Translate between Unicode character names and their code points.
#
# The official names with their code points are stored in a table in
# lib/unicore/Name.pl which is read in as a large string (almost 3/4 Mb in
# Unicode 6.0).  Each code point/name combination is separated by a \n in the
# string.  (Some of the CJK and the Hangul syllable names are determined
# instead algorithmically via subroutines also stored in Name.pl).  Because of
# the large size of this table, it isn't converted into hashes for faster
# lookup.
#
# But, user defined aliases are stored in their own hashes, as are Perl
# extensions to the official names.  These are checked first before looking at
# the official table.
#
# Basically, the table is grepped for the input code point (viacode()) or
# name (the other functions), and the corresponding value on the same line is
# returned.  The grepping is done by turning the input into a regular
# expression.  Thus, the same table does double duty, used by both name and
# code point lookup.  (If we were to have hashes, we would need two, one for
# each lookup direction.)
#
# For loose name matching, the logical thing would be to have a table
# with all the ignorable characters squeezed out, and then grep it with the
# similiarly-squeezed input name.  (And this is in fact how the lookups are
# done with the small Perl extension hashes.)  But since we need to be able to
# go from code point to official name, the original table would still need to
# exist.  Due to the large size of the table, it was decided to not read
# another very large string into memory for a second table.  Instead, the
# regular expression of the input name is modified to have optional spaces and
# dashes between characters.  For example, in strict matching, the regular
# expression would be:
#   qr/\tDIGIT ONE$/m
# Under loose matching, the blank would be squeezed out, and the re would be:
#   qr/\tD[- ]?I[- ]?G[- ]?I[- ]?T[- ]?O[- ]?N[- ]?E$/m
# which matches a blank or dash between any characters in the official table.
#
# This is also how script lookup is done.  Basically the re looks like
#   qr/ (?:LATIN|GREEK|CYRILLIC) (?:SMALL )?LETTER $name/
# where $name is the loose or strict regex for the remainder of the name.

# The hashes are stored as utf8 strings.  This makes it easier to deal with
# sequences.  I (khw) also tried making Name.pl utf8, but it slowed things
# down by a factor of 7.  I then tried making Name.pl store the ut8
# equivalents but not calling them utf8.  That led to similar speed as leaving
# it alone, but since that is harder for a human to parse, I left it as-is.

my %system_aliases = (
    # Synonyms for the icky 3.2 names that have parentheses.
    'LINE FEED'             => pack("U", 0x0A), # LINE FEED (LF)
    'FORM FEED'             => pack("U", 0x0C), # FORM FEED (FF)
    'CARRIAGE RETURN'       => pack("U", 0x0D), # CARRIAGE RETURN (CR)
    'NEXT LINE'             => pack("U", 0x85), # NEXT LINE (NEL)

    # Some variant names from Wikipedia
    'SINGLE-SHIFT 2'                => pack("U", 0x8E),
    'SINGLE-SHIFT 3'                => pack("U", 0x8F),
    'PRIVATE USE 1'                 => pack("U", 0x91),
    'PRIVATE USE 2'                 => pack("U", 0x92),
    'START OF PROTECTED AREA'       => pack("U", 0x96),
    'END OF PROTECTED AREA'         => pack("U", 0x97),

    # Convenience.  Standard abbreviations for the controls
    'NUL'           => pack("U", 0x00), # NULL
    'SOH'           => pack("U", 0x01), # START OF HEADING
    'STX'           => pack("U", 0x02), # START OF TEXT
    'ETX'           => pack("U", 0x03), # END OF TEXT
    'EOT'           => pack("U", 0x04), # END OF TRANSMISSION
    'ENQ'           => pack("U", 0x05), # ENQUIRY
    'ACK'           => pack("U", 0x06), # ACKNOWLEDGE
    'BEL'           => pack("U", 0x07), # ALERT; formerly BELL
    'BS'            => pack("U", 0x08), # BACKSPACE
    'HT'            => pack("U", 0x09), # HORIZONTAL TABULATION
    'LF'            => pack("U", 0x0A), # LINE FEED (LF)
    'VT'            => pack("U", 0x0B), # VERTICAL TABULATION
    'FF'            => pack("U", 0x0C), # FORM FEED (FF)
    'CR'            => pack("U", 0x0D), # CARRIAGE RETURN (CR)
    'SO'            => pack("U", 0x0E), # SHIFT OUT
    'SI'            => pack("U", 0x0F), # SHIFT IN
    'DLE'           => pack("U", 0x10), # DATA LINK ESCAPE
    'DC1'           => pack("U", 0x11), # DEVICE CONTROL ONE
    'DC2'           => pack("U", 0x12), # DEVICE CONTROL TWO
    'DC3'           => pack("U", 0x13), # DEVICE CONTROL THREE
    'DC4'           => pack("U", 0x14), # DEVICE CONTROL FOUR
    'NAK'           => pack("U", 0x15), # NEGATIVE ACKNOWLEDGE
    'SYN'           => pack("U", 0x16), # SYNCHRONOUS IDLE
    'ETB'           => pack("U", 0x17), # END OF TRANSMISSION BLOCK
    'CAN'           => pack("U", 0x18), # CANCEL
    'EOM'           => pack("U", 0x19), # END OF MEDIUM
    'SUB'           => pack("U", 0x1A), # SUBSTITUTE
    'ESC'           => pack("U", 0x1B), # ESCAPE
    'FS'            => pack("U", 0x1C), # FILE SEPARATOR
    'GS'            => pack("U", 0x1D), # GROUP SEPARATOR
    'RS'            => pack("U", 0x1E), # RECORD SEPARATOR
    'US'            => pack("U", 0x1F), # UNIT SEPARATOR
    'DEL'           => pack("U", 0x7F), # DELETE
    'BPH'           => pack("U", 0x82), # BREAK PERMITTED HERE
    'NBH'           => pack("U", 0x83), # NO BREAK HERE
    'NEL'           => pack("U", 0x85), # NEXT LINE (NEL)
    'SSA'           => pack("U", 0x86), # START OF SELECTED AREA
    'ESA'           => pack("U", 0x87), # END OF SELECTED AREA
    'HTS'           => pack("U", 0x88), # CHARACTER TABULATION SET
    'HTJ'           => pack("U", 0x89), # CHARACTER TABULATION WITH JUSTIFICATION
    'VTS'           => pack("U", 0x8A), # LINE TABULATION SET
    'PLD'           => pack("U", 0x8B), # PARTIAL LINE FORWARD
    'PLU'           => pack("U", 0x8C), # PARTIAL LINE BACKWARD
    'RI'            => pack("U", 0x8D), # REVERSE LINE FEED
    'SS2'           => pack("U", 0x8E), # SINGLE SHIFT TWO
    'SS3'           => pack("U", 0x8F), # SINGLE SHIFT THREE
    'DCS'           => pack("U", 0x90), # DEVICE CONTROL STRING
    'PU1'           => pack("U", 0x91), # PRIVATE USE ONE
    'PU2'           => pack("U", 0x92), # PRIVATE USE TWO
    'STS'           => pack("U", 0x93), # SET TRANSMIT STATE
    'CCH'           => pack("U", 0x94), # CANCEL CHARACTER
    'MW'            => pack("U", 0x95), # MESSAGE WAITING
    'SPA'           => pack("U", 0x96), # START OF GUARDED AREA
    'EPA'           => pack("U", 0x97), # END OF GUARDED AREA
    'SOS'           => pack("U", 0x98), # START OF STRING
    'SCI'           => pack("U", 0x9A), # SINGLE CHARACTER INTRODUCER
    'CSI'           => pack("U", 0x9B), # CONTROL SEQUENCE INTRODUCER
    'ST'            => pack("U", 0x9C), # STRING TERMINATOR
    'OSC'           => pack("U", 0x9D), # OPERATING SYSTEM COMMAND
    'PM'            => pack("U", 0x9E), # PRIVACY MESSAGE
    'APC'           => pack("U", 0x9F), # APPLICATION PROGRAM COMMAND

    # There are no names for these in the Unicode standard; perhaps should be
    # deprecated, but then again there are no alternative names, so am not
    # deprecating.  And if did, the code would have to change to not recommend
    # an alternative for these.
    'PADDING CHARACTER'                     => pack("U", 0x80),
    'PAD'                                   => pack("U", 0x80),
    'HIGH OCTET PRESET'                     => pack("U", 0x81),
    'HOP'                                   => pack("U", 0x81),
    'INDEX'                                 => pack("U", 0x84),
    'IND'                                   => pack("U", 0x84),
    'SINGLE GRAPHIC CHARACTER INTRODUCER'   => pack("U", 0x99),
    'SGC'                                   => pack("U", 0x99),

    # More convenience.  For further convenience, it is suggested some way of
    # using the NamesList aliases be implemented, but there are ambiguities in
    # NamesList.txt
    'BOM'   => pack("U", 0xFEFF), # BYTE ORDER MARK
    'BYTE ORDER MARK'=> pack("U", 0xFEFF),
    'CGJ'   => pack("U", 0x034F), # COMBINING GRAPHEME JOINER
    'FVS1'  => pack("U", 0x180B), # MONGOLIAN FREE VARIATION SELECTOR ONE
    'FVS2'  => pack("U", 0x180C), # MONGOLIAN FREE VARIATION SELECTOR TWO
    'FVS3'  => pack("U", 0x180D), # MONGOLIAN FREE VARIATION SELECTOR THREE
    'LRE'   => pack("U", 0x202A), # LEFT-TO-RIGHT EMBEDDING
    'LRM'   => pack("U", 0x200E), # LEFT-TO-RIGHT MARK
    'LRO'   => pack("U", 0x202D), # LEFT-TO-RIGHT OVERRIDE
    'MMSP'  => pack("U", 0x205F), # MEDIUM MATHEMATICAL SPACE
    'MVS'   => pack("U", 0x180E), # MONGOLIAN VOWEL SEPARATOR
    'NBSP'  => pack("U", 0x00A0), # NO-BREAK SPACE
    'NNBSP' => pack("U", 0x202F), # NARROW NO-BREAK SPACE
    'PDF'   => pack("U", 0x202C), # POP DIRECTIONAL FORMATTING
    'RLE'   => pack("U", 0x202B), # RIGHT-TO-LEFT EMBEDDING
    'RLM'   => pack("U", 0x200F), # RIGHT-TO-LEFT MARK
    'RLO'   => pack("U", 0x202E), # RIGHT-TO-LEFT OVERRIDE
    'SHY'   => pack("U", 0x00AD), # SOFT HYPHEN
    'VS1'   => pack("U", 0xFE00), # VARIATION SELECTOR-1
    'VS2'   => pack("U", 0xFE01), # VARIATION SELECTOR-2
    'VS3'   => pack("U", 0xFE02), # VARIATION SELECTOR-3
    'VS4'   => pack("U", 0xFE03), # VARIATION SELECTOR-4
    'VS5'   => pack("U", 0xFE04), # VARIATION SELECTOR-5
    'VS6'   => pack("U", 0xFE05), # VARIATION SELECTOR-6
    'VS7'   => pack("U", 0xFE06), # VARIATION SELECTOR-7
    'VS8'   => pack("U", 0xFE07), # VARIATION SELECTOR-8
    'VS9'   => pack("U", 0xFE08), # VARIATION SELECTOR-9
    'VS10'  => pack("U", 0xFE09), # VARIATION SELECTOR-10
    'VS11'  => pack("U", 0xFE0A), # VARIATION SELECTOR-11
    'VS12'  => pack("U", 0xFE0B), # VARIATION SELECTOR-12
    'VS13'  => pack("U", 0xFE0C), # VARIATION SELECTOR-13
    'VS14'  => pack("U", 0xFE0D), # VARIATION SELECTOR-14
    'VS15'  => pack("U", 0xFE0E), # VARIATION SELECTOR-15
    'VS16'  => pack("U", 0xFE0F), # VARIATION SELECTOR-16
    'VS17'  => pack("U", 0xE0100), # VARIATION SELECTOR-17
    'VS18'  => pack("U", 0xE0101), # VARIATION SELECTOR-18
    'VS19'  => pack("U", 0xE0102), # VARIATION SELECTOR-19
    'VS20'  => pack("U", 0xE0103), # VARIATION SELECTOR-20
    'VS21'  => pack("U", 0xE0104), # VARIATION SELECTOR-21
    'VS22'  => pack("U", 0xE0105), # VARIATION SELECTOR-22
    'VS23'  => pack("U", 0xE0106), # VARIATION SELECTOR-23
    'VS24'  => pack("U", 0xE0107), # VARIATION SELECTOR-24
    'VS25'  => pack("U", 0xE0108), # VARIATION SELECTOR-25
    'VS26'  => pack("U", 0xE0109), # VARIATION SELECTOR-26
    'VS27'  => pack("U", 0xE010A), # VARIATION SELECTOR-27
    'VS28'  => pack("U", 0xE010B), # VARIATION SELECTOR-28
    'VS29'  => pack("U", 0xE010C), # VARIATION SELECTOR-29
    'VS30'  => pack("U", 0xE010D), # VARIATION SELECTOR-30
    'VS31'  => pack("U", 0xE010E), # VARIATION SELECTOR-31
    'VS32'  => pack("U", 0xE010F), # VARIATION SELECTOR-32
    'VS33'  => pack("U", 0xE0110), # VARIATION SELECTOR-33
    'VS34'  => pack("U", 0xE0111), # VARIATION SELECTOR-34
    'VS35'  => pack("U", 0xE0112), # VARIATION SELECTOR-35
    'VS36'  => pack("U", 0xE0113), # VARIATION SELECTOR-36
    'VS37'  => pack("U", 0xE0114), # VARIATION SELECTOR-37
    'VS38'  => pack("U", 0xE0115), # VARIATION SELECTOR-38
    'VS39'  => pack("U", 0xE0116), # VARIATION SELECTOR-39
    'VS40'  => pack("U", 0xE0117), # VARIATION SELECTOR-40
    'VS41'  => pack("U", 0xE0118), # VARIATION SELECTOR-41
    'VS42'  => pack("U", 0xE0119), # VARIATION SELECTOR-42
    'VS43'  => pack("U", 0xE011A), # VARIATION SELECTOR-43
    'VS44'  => pack("U", 0xE011B), # VARIATION SELECTOR-44
    'VS45'  => pack("U", 0xE011C), # VARIATION SELECTOR-45
    'VS46'  => pack("U", 0xE011D), # VARIATION SELECTOR-46
    'VS47'  => pack("U", 0xE011E), # VARIATION SELECTOR-47
    'VS48'  => pack("U", 0xE011F), # VARIATION SELECTOR-48
    'VS49'  => pack("U", 0xE0120), # VARIATION SELECTOR-49
    'VS50'  => pack("U", 0xE0121), # VARIATION SELECTOR-50
    'VS51'  => pack("U", 0xE0122), # VARIATION SELECTOR-51
    'VS52'  => pack("U", 0xE0123), # VARIATION SELECTOR-52
    'VS53'  => pack("U", 0xE0124), # VARIATION SELECTOR-53
    'VS54'  => pack("U", 0xE0125), # VARIATION SELECTOR-54
    'VS55'  => pack("U", 0xE0126), # VARIATION SELECTOR-55
    'VS56'  => pack("U", 0xE0127), # VARIATION SELECTOR-56
    'VS57'  => pack("U", 0xE0128), # VARIATION SELECTOR-57
    'VS58'  => pack("U", 0xE0129), # VARIATION SELECTOR-58
    'VS59'  => pack("U", 0xE012A), # VARIATION SELECTOR-59
    'VS60'  => pack("U", 0xE012B), # VARIATION SELECTOR-60
    'VS61'  => pack("U", 0xE012C), # VARIATION SELECTOR-61
    'VS62'  => pack("U", 0xE012D), # VARIATION SELECTOR-62
    'VS63'  => pack("U", 0xE012E), # VARIATION SELECTOR-63
    'VS64'  => pack("U", 0xE012F), # VARIATION SELECTOR-64
    'VS65'  => pack("U", 0xE0130), # VARIATION SELECTOR-65
    'VS66'  => pack("U", 0xE0131), # VARIATION SELECTOR-66
    'VS67'  => pack("U", 0xE0132), # VARIATION SELECTOR-67
    'VS68'  => pack("U", 0xE0133), # VARIATION SELECTOR-68
    'VS69'  => pack("U", 0xE0134), # VARIATION SELECTOR-69
    'VS70'  => pack("U", 0xE0135), # VARIATION SELECTOR-70
    'VS71'  => pack("U", 0xE0136), # VARIATION SELECTOR-71
    'VS72'  => pack("U", 0xE0137), # VARIATION SELECTOR-72
    'VS73'  => pack("U", 0xE0138), # VARIATION SELECTOR-73
    'VS74'  => pack("U", 0xE0139), # VARIATION SELECTOR-74
    'VS75'  => pack("U", 0xE013A), # VARIATION SELECTOR-75
    'VS76'  => pack("U", 0xE013B), # VARIATION SELECTOR-76
    'VS77'  => pack("U", 0xE013C), # VARIATION SELECTOR-77
    'VS78'  => pack("U", 0xE013D), # VARIATION SELECTOR-78
    'VS79'  => pack("U", 0xE013E), # VARIATION SELECTOR-79
    'VS80'  => pack("U", 0xE013F), # VARIATION SELECTOR-80
    'VS81'  => pack("U", 0xE0140), # VARIATION SELECTOR-81
    'VS82'  => pack("U", 0xE0141), # VARIATION SELECTOR-82
    'VS83'  => pack("U", 0xE0142), # VARIATION SELECTOR-83
    'VS84'  => pack("U", 0xE0143), # VARIATION SELECTOR-84
    'VS85'  => pack("U", 0xE0144), # VARIATION SELECTOR-85
    'VS86'  => pack("U", 0xE0145), # VARIATION SELECTOR-86
    'VS87'  => pack("U", 0xE0146), # VARIATION SELECTOR-87
    'VS88'  => pack("U", 0xE0147), # VARIATION SELECTOR-88
    'VS89'  => pack("U", 0xE0148), # VARIATION SELECTOR-89
    'VS90'  => pack("U", 0xE0149), # VARIATION SELECTOR-90
    'VS91'  => pack("U", 0xE014A), # VARIATION SELECTOR-91
    'VS92'  => pack("U", 0xE014B), # VARIATION SELECTOR-92
    'VS93'  => pack("U", 0xE014C), # VARIATION SELECTOR-93
    'VS94'  => pack("U", 0xE014D), # VARIATION SELECTOR-94
    'VS95'  => pack("U", 0xE014E), # VARIATION SELECTOR-95
    'VS96'  => pack("U", 0xE014F), # VARIATION SELECTOR-96
    'VS97'  => pack("U", 0xE0150), # VARIATION SELECTOR-97
    'VS98'  => pack("U", 0xE0151), # VARIATION SELECTOR-98
    'VS99'  => pack("U", 0xE0152), # VARIATION SELECTOR-99
    'VS100' => pack("U", 0xE0153), # VARIATION SELECTOR-100
    'VS101' => pack("U", 0xE0154), # VARIATION SELECTOR-101
    'VS102' => pack("U", 0xE0155), # VARIATION SELECTOR-102
    'VS103' => pack("U", 0xE0156), # VARIATION SELECTOR-103
    'VS104' => pack("U", 0xE0157), # VARIATION SELECTOR-104
    'VS105' => pack("U", 0xE0158), # VARIATION SELECTOR-105
    'VS106' => pack("U", 0xE0159), # VARIATION SELECTOR-106
    'VS107' => pack("U", 0xE015A), # VARIATION SELECTOR-107
    'VS108' => pack("U", 0xE015B), # VARIATION SELECTOR-108
    'VS109' => pack("U", 0xE015C), # VARIATION SELECTOR-109
    'VS110' => pack("U", 0xE015D), # VARIATION SELECTOR-110
    'VS111' => pack("U", 0xE015E), # VARIATION SELECTOR-111
    'VS112' => pack("U", 0xE015F), # VARIATION SELECTOR-112
    'VS113' => pack("U", 0xE0160), # VARIATION SELECTOR-113
    'VS114' => pack("U", 0xE0161), # VARIATION SELECTOR-114
    'VS115' => pack("U", 0xE0162), # VARIATION SELECTOR-115
    'VS116' => pack("U", 0xE0163), # VARIATION SELECTOR-116
    'VS117' => pack("U", 0xE0164), # VARIATION SELECTOR-117
    'VS118' => pack("U", 0xE0165), # VARIATION SELECTOR-118
    'VS119' => pack("U", 0xE0166), # VARIATION SELECTOR-119
    'VS120' => pack("U", 0xE0167), # VARIATION SELECTOR-120
    'VS121' => pack("U", 0xE0168), # VARIATION SELECTOR-121
    'VS122' => pack("U", 0xE0169), # VARIATION SELECTOR-122
    'VS123' => pack("U", 0xE016A), # VARIATION SELECTOR-123
    'VS124' => pack("U", 0xE016B), # VARIATION SELECTOR-124
    'VS125' => pack("U", 0xE016C), # VARIATION SELECTOR-125
    'VS126' => pack("U", 0xE016D), # VARIATION SELECTOR-126
    'VS127' => pack("U", 0xE016E), # VARIATION SELECTOR-127
    'VS128' => pack("U", 0xE016F), # VARIATION SELECTOR-128
    'VS129' => pack("U", 0xE0170), # VARIATION SELECTOR-129
    'VS130' => pack("U", 0xE0171), # VARIATION SELECTOR-130
    'VS131' => pack("U", 0xE0172), # VARIATION SELECTOR-131
    'VS132' => pack("U", 0xE0173), # VARIATION SELECTOR-132
    'VS133' => pack("U", 0xE0174), # VARIATION SELECTOR-133
    'VS134' => pack("U", 0xE0175), # VARIATION SELECTOR-134
    'VS135' => pack("U", 0xE0176), # VARIATION SELECTOR-135
    'VS136' => pack("U", 0xE0177), # VARIATION SELECTOR-136
    'VS137' => pack("U", 0xE0178), # VARIATION SELECTOR-137
    'VS138' => pack("U", 0xE0179), # VARIATION SELECTOR-138
    'VS139' => pack("U", 0xE017A), # VARIATION SELECTOR-139
    'VS140' => pack("U", 0xE017B), # VARIATION SELECTOR-140
    'VS141' => pack("U", 0xE017C), # VARIATION SELECTOR-141
    'VS142' => pack("U", 0xE017D), # VARIATION SELECTOR-142
    'VS143' => pack("U", 0xE017E), # VARIATION SELECTOR-143
    'VS144' => pack("U", 0xE017F), # VARIATION SELECTOR-144
    'VS145' => pack("U", 0xE0180), # VARIATION SELECTOR-145
    'VS146' => pack("U", 0xE0181), # VARIATION SELECTOR-146
    'VS147' => pack("U", 0xE0182), # VARIATION SELECTOR-147
    'VS148' => pack("U", 0xE0183), # VARIATION SELECTOR-148
    'VS149' => pack("U", 0xE0184), # VARIATION SELECTOR-149
    'VS150' => pack("U", 0xE0185), # VARIATION SELECTOR-150
    'VS151' => pack("U", 0xE0186), # VARIATION SELECTOR-151
    'VS152' => pack("U", 0xE0187), # VARIATION SELECTOR-152
    'VS153' => pack("U", 0xE0188), # VARIATION SELECTOR-153
    'VS154' => pack("U", 0xE0189), # VARIATION SELECTOR-154
    'VS155' => pack("U", 0xE018A), # VARIATION SELECTOR-155
    'VS156' => pack("U", 0xE018B), # VARIATION SELECTOR-156
    'VS157' => pack("U", 0xE018C), # VARIATION SELECTOR-157
    'VS158' => pack("U", 0xE018D), # VARIATION SELECTOR-158
    'VS159' => pack("U", 0xE018E), # VARIATION SELECTOR-159
    'VS160' => pack("U", 0xE018F), # VARIATION SELECTOR-160
    'VS161' => pack("U", 0xE0190), # VARIATION SELECTOR-161
    'VS162' => pack("U", 0xE0191), # VARIATION SELECTOR-162
    'VS163' => pack("U", 0xE0192), # VARIATION SELECTOR-163
    'VS164' => pack("U", 0xE0193), # VARIATION SELECTOR-164
    'VS165' => pack("U", 0xE0194), # VARIATION SELECTOR-165
    'VS166' => pack("U", 0xE0195), # VARIATION SELECTOR-166
    'VS167' => pack("U", 0xE0196), # VARIATION SELECTOR-167
    'VS168' => pack("U", 0xE0197), # VARIATION SELECTOR-168
    'VS169' => pack("U", 0xE0198), # VARIATION SELECTOR-169
    'VS170' => pack("U", 0xE0199), # VARIATION SELECTOR-170
    'VS171' => pack("U", 0xE019A), # VARIATION SELECTOR-171
    'VS172' => pack("U", 0xE019B), # VARIATION SELECTOR-172
    'VS173' => pack("U", 0xE019C), # VARIATION SELECTOR-173
    'VS174' => pack("U", 0xE019D), # VARIATION SELECTOR-174
    'VS175' => pack("U", 0xE019E), # VARIATION SELECTOR-175
    'VS176' => pack("U", 0xE019F), # VARIATION SELECTOR-176
    'VS177' => pack("U", 0xE01A0), # VARIATION SELECTOR-177
    'VS178' => pack("U", 0xE01A1), # VARIATION SELECTOR-178
    'VS179' => pack("U", 0xE01A2), # VARIATION SELECTOR-179
    'VS180' => pack("U", 0xE01A3), # VARIATION SELECTOR-180
    'VS181' => pack("U", 0xE01A4), # VARIATION SELECTOR-181
    'VS182' => pack("U", 0xE01A5), # VARIATION SELECTOR-182
    'VS183' => pack("U", 0xE01A6), # VARIATION SELECTOR-183
    'VS184' => pack("U", 0xE01A7), # VARIATION SELECTOR-184
    'VS185' => pack("U", 0xE01A8), # VARIATION SELECTOR-185
    'VS186' => pack("U", 0xE01A9), # VARIATION SELECTOR-186
    'VS187' => pack("U", 0xE01AA), # VARIATION SELECTOR-187
    'VS188' => pack("U", 0xE01AB), # VARIATION SELECTOR-188
    'VS189' => pack("U", 0xE01AC), # VARIATION SELECTOR-189
    'VS190' => pack("U", 0xE01AD), # VARIATION SELECTOR-190
    'VS191' => pack("U", 0xE01AE), # VARIATION SELECTOR-191
    'VS192' => pack("U", 0xE01AF), # VARIATION SELECTOR-192
    'VS193' => pack("U", 0xE01B0), # VARIATION SELECTOR-193
    'VS194' => pack("U", 0xE01B1), # VARIATION SELECTOR-194
    'VS195' => pack("U", 0xE01B2), # VARIATION SELECTOR-195
    'VS196' => pack("U", 0xE01B3), # VARIATION SELECTOR-196
    'VS197' => pack("U", 0xE01B4), # VARIATION SELECTOR-197
    'VS198' => pack("U", 0xE01B5), # VARIATION SELECTOR-198
    'VS199' => pack("U", 0xE01B6), # VARIATION SELECTOR-199
    'VS200' => pack("U", 0xE01B7), # VARIATION SELECTOR-200
    'VS201' => pack("U", 0xE01B8), # VARIATION SELECTOR-201
    'VS202' => pack("U", 0xE01B9), # VARIATION SELECTOR-202
    'VS203' => pack("U", 0xE01BA), # VARIATION SELECTOR-203
    'VS204' => pack("U", 0xE01BB), # VARIATION SELECTOR-204
    'VS205' => pack("U", 0xE01BC), # VARIATION SELECTOR-205
    'VS206' => pack("U", 0xE01BD), # VARIATION SELECTOR-206
    'VS207' => pack("U", 0xE01BE), # VARIATION SELECTOR-207
    'VS208' => pack("U", 0xE01BF), # VARIATION SELECTOR-208
    'VS209' => pack("U", 0xE01C0), # VARIATION SELECTOR-209
    'VS210' => pack("U", 0xE01C1), # VARIATION SELECTOR-210
    'VS211' => pack("U", 0xE01C2), # VARIATION SELECTOR-211
    'VS212' => pack("U", 0xE01C3), # VARIATION SELECTOR-212
    'VS213' => pack("U", 0xE01C4), # VARIATION SELECTOR-213
    'VS214' => pack("U", 0xE01C5), # VARIATION SELECTOR-214
    'VS215' => pack("U", 0xE01C6), # VARIATION SELECTOR-215
    'VS216' => pack("U", 0xE01C7), # VARIATION SELECTOR-216
    'VS217' => pack("U", 0xE01C8), # VARIATION SELECTOR-217
    'VS218' => pack("U", 0xE01C9), # VARIATION SELECTOR-218
    'VS219' => pack("U", 0xE01CA), # VARIATION SELECTOR-219
    'VS220' => pack("U", 0xE01CB), # VARIATION SELECTOR-220
    'VS221' => pack("U", 0xE01CC), # VARIATION SELECTOR-221
    'VS222' => pack("U", 0xE01CD), # VARIATION SELECTOR-222
    'VS223' => pack("U", 0xE01CE), # VARIATION SELECTOR-223
    'VS224' => pack("U", 0xE01CF), # VARIATION SELECTOR-224
    'VS225' => pack("U", 0xE01D0), # VARIATION SELECTOR-225
    'VS226' => pack("U", 0xE01D1), # VARIATION SELECTOR-226
    'VS227' => pack("U", 0xE01D2), # VARIATION SELECTOR-227
    'VS228' => pack("U", 0xE01D3), # VARIATION SELECTOR-228
    'VS229' => pack("U", 0xE01D4), # VARIATION SELECTOR-229
    'VS230' => pack("U", 0xE01D5), # VARIATION SELECTOR-230
    'VS231' => pack("U", 0xE01D6), # VARIATION SELECTOR-231
    'VS232' => pack("U", 0xE01D7), # VARIATION SELECTOR-232
    'VS233' => pack("U", 0xE01D8), # VARIATION SELECTOR-233
    'VS234' => pack("U", 0xE01D9), # VARIATION SELECTOR-234
    'VS235' => pack("U", 0xE01DA), # VARIATION SELECTOR-235
    'VS236' => pack("U", 0xE01DB), # VARIATION SELECTOR-236
    'VS237' => pack("U", 0xE01DC), # VARIATION SELECTOR-237
    'VS238' => pack("U", 0xE01DD), # VARIATION SELECTOR-238
    'VS239' => pack("U", 0xE01DE), # VARIATION SELECTOR-239
    'VS240' => pack("U", 0xE01DF), # VARIATION SELECTOR-240
    'VS241' => pack("U", 0xE01E0), # VARIATION SELECTOR-241
    'VS242' => pack("U", 0xE01E1), # VARIATION SELECTOR-242
    'VS243' => pack("U", 0xE01E2), # VARIATION SELECTOR-243
    'VS244' => pack("U", 0xE01E3), # VARIATION SELECTOR-244
    'VS245' => pack("U", 0xE01E4), # VARIATION SELECTOR-245
    'VS246' => pack("U", 0xE01E5), # VARIATION SELECTOR-246
    'VS247' => pack("U", 0xE01E6), # VARIATION SELECTOR-247
    'VS248' => pack("U", 0xE01E7), # VARIATION SELECTOR-248
    'VS249' => pack("U", 0xE01E8), # VARIATION SELECTOR-249
    'VS250' => pack("U", 0xE01E9), # VARIATION SELECTOR-250
    'VS251' => pack("U", 0xE01EA), # VARIATION SELECTOR-251
    'VS252' => pack("U", 0xE01EB), # VARIATION SELECTOR-252
    'VS253' => pack("U", 0xE01EC), # VARIATION SELECTOR-253
    'VS254' => pack("U", 0xE01ED), # VARIATION SELECTOR-254
    'VS255' => pack("U", 0xE01EE), # VARIATION SELECTOR-255
    'VS256' => pack("U", 0xE01EF), # VARIATION SELECTOR-256
    'WJ'    => pack("U", 0x2060), # WORD JOINER
    'ZWJ'   => pack("U", 0x200D), # ZERO WIDTH JOINER
    'ZWNJ'  => pack("U", 0x200C), # ZERO WIDTH NON-JOINER
    'ZWSP'  => pack("U", 0x200B), # ZERO WIDTH SPACE
);

# These are the aliases above that differ under :loose and :full matching
# because the :full versions have blanks or hyphens in them.
my %loose_system_aliases = (
    'LINEFEED'                         => pack("U", 0x0A),
    'FORMFEED'                         => pack("U", 0x0C),
    'CARRIAGERETURN'                   => pack("U", 0x0D),
    'NEXTLINE'                         => pack("U", 0x85),
    'SINGLESHIFT2'                     => pack("U", 0x8E),
    'SINGLESHIFT3'                     => pack("U", 0x8F),
    'PRIVATEUSE1'                      => pack("U", 0x91),
    'PRIVATEUSE2'                      => pack("U", 0x92),
    'STARTOFPROTECTEDAREA'             => pack("U", 0x96),
    'ENDOFPROTECTEDAREA'               => pack("U", 0x97),
    'PADDINGCHARACTER'                 => pack("U", 0x80),
    'HIGHOCTETPRESET'                  => pack("U", 0x81),
    'SINGLEGRAPHICCHARACTERINTRODUCER' => pack("U", 0x99),
    'BYTEORDERMARK'                    => pack("U", 0xFEFF),
);

my %deprecated_aliases = (
    # Pre-3.2 compatibility (only for the first 256 characters).
    # Use of these gives deprecated message.
    'HORIZONTAL TABULATION' => pack("U", 0x09), # CHARACTER TABULATION
    'VERTICAL TABULATION'   => pack("U", 0x0B), # LINE TABULATION
    'FILE SEPARATOR'        => pack("U", 0x1C), # INFORMATION SEPARATOR FOUR
    'GROUP SEPARATOR'       => pack("U", 0x1D), # INFORMATION SEPARATOR THREE
    'RECORD SEPARATOR'      => pack("U", 0x1E), # INFORMATION SEPARATOR TWO
    'UNIT SEPARATOR'        => pack("U", 0x1F), # INFORMATION SEPARATOR ONE
    'HORIZONTAL TABULATION SET' => pack("U", 0x88), # CHARACTER TABULATION SET
    'HORIZONTAL TABULATION WITH JUSTIFICATION' => pack("U", 0x89), # CHARACTER TABULATION WITH JUSTIFICATION
    'PARTIAL LINE DOWN'       => pack("U", 0x8B), # PARTIAL LINE FORWARD
    'PARTIAL LINE UP'         => pack("U", 0x8C), # PARTIAL LINE BACKWARD
    'VERTICAL TABULATION SET' => pack("U", 0x8A), # LINE TABULATION SET
    'REVERSE INDEX'           => pack("U", 0x8D), # REVERSE LINE FEED

    # Unicode 6.0 co-opted this for U+1F514, so deprecate it for now.
    'BELL'                    => pack("U", 0x07),
);

my %loose_deprecated_aliases = (
    'HORIZONTALTABULATION'                  => pack("U", 0x09),
    'VERTICALTABULATION'                    => pack("U", 0x0B),
    'FILESEPARATOR'                         => pack("U", 0x1C),
    'GROUPSEPARATOR'                        => pack("U", 0x1D),
    'RECORDSEPARATOR'                       => pack("U", 0x1E),
    'UNITSEPARATOR'                         => pack("U", 0x1F),
    'HORIZONTALTABULATIONSET'               => pack("U", 0x88),
    'HORIZONTALTABULATIONWITHJUSTIFICATION' => pack("U", 0x89),
    'PARTIALLINEDOWN'                       => pack("U", 0x8B),
    'PARTIALLINEUP'                         => pack("U", 0x8C),
    'VERTICALTABULATIONSET'                 => pack("U", 0x8A),
    'REVERSEINDEX'                          => pack("U", 0x8D),
);

# These are special cased in :loose matching, differing only in a medial
# hyphen
my $HANGUL_JUNGSEONG_O_E_utf8 = pack("U", 0x1180);
my $HANGUL_JUNGSEONG_OE_utf8 = pack("U", 0x116C);


my $txt;  # The table of official character names

my %full_names_cache; # Holds already-looked-up names, so don't have to
# re-look them up again.  The previous versions of charnames had scoping
# bugs.  For example if we use script A in one scope and find and cache
# what Z resolves to, we can't use that cache in a different scope that
# uses script B instead of A, as Z might be an entirely different letter
# there; or there might be different aliases in effect in different
# scopes, or :short may be in effect or not effect in different scopes,
# or various combinations thereof.  This was solved in this version
# mostly by moving things to %^H.  But some things couldn't be moved
# there.  One of them was the cache of runtime looked-up names, in part
# because %^H is read-only at runtime.  I (khw) don't know why the cache
# was run-time only in the previous versions: perhaps oversight; perhaps
# that compile time looking doesn't happen in a loop so didn't think it
# was worthwhile; perhaps not wanting to make the cache too large.  But
# I decided to make it compile time as well; this could easily be
# changed.
# Anyway, this hash is not scoped, and is added to at runtime.  It
# doesn't have scoping problems because the data in it is restricted to
# official names, which are always invariant, and we only set it and
# look at it at during :full lookups, so is unaffected by any other
# scoped options.  I put this in to maintain parity with the older
# version.  If desired, a %short_names cache could also be made, as well
# as one for each script, say in %script_names_cache, with each key
# being a hash for a script named in a 'use charnames' statement.  I
# decided not to do that for now, just because it's added complication,
# and because I'm just trying to maintain parity, not extend it.

# Like %full_names_cache, but for use when :loose is in effect.  There needs
# to be two caches because :loose may not be in effect for a scope, and a
# loose name could inappropriately be returned when only exact matching is
# called for.
my %loose_names_cache;

# Designed so that test decimal first, and then hex.  Leading zeros
# imply non-decimal, as do non-[0-9]
my $decimal_qr = qr/^[1-9]\d*$/;

# Returns the hex number in $1.
my $hex_qr = qr/^(?:[Uu]\+|0[xX])?([[:xdigit:]]+)$/;

sub croak
{
  require Carp; goto &Carp::croak;
} # croak

sub carp
{
  require Carp; goto &Carp::carp;
} # carp

sub alias (@) # Set up a single alias
{
  my $alias = ref $_[0] ? $_[0] : { @_ };
  foreach my $name (keys %$alias) {
    my $value = $alias->{$name};
    next unless defined $value;          # Omit if screwed up.

    # Is slightly slower to just after this statement see if it is
    # decimal, since we already know it is after having converted from
    # hex, but makes the code easier to maintain, and is called
    # infrequently, only at compile-time
    if ($value !~ $decimal_qr && $value =~ $hex_qr) {
      $value = CORE::hex $1;
    }
    if ($value =~ $decimal_qr) {
        no warnings qw(non_unicode surrogate nonchar); # Allow any non-malformed
        $^H{charnames_ord_aliases}{$name} = pack("U", $value);

        # Use a canonical form.
        $^H{charnames_inverse_ords}{sprintf("%05X", $value)} = $name;
    }
    else {
        # XXX validate syntax when deprecation cycle complete. ie. start
        # with an alpha only, etc.
        $^H{charnames_name_aliases}{$name} = $value;
    }
  }
} # alias

sub not_legal_use_bytes_msg {
  my ($name, $utf8) = @_;
  my $return;

  if (length($utf8) == 1) {
    $return = sprintf("Character 0x%04x with name '%s' is", ord $utf8, $name);
  } else {
    $return = sprintf("String with name '%s' (and ordinals %s) contains character(s)", $name, join(" ", map { sprintf "0x%04X", ord $_ } split(//, $utf8)));
  }
  return $return . " above 0xFF with 'use bytes' in effect";
}

sub alias_file ($)  # Reads a file containing alias definitions
{
  my ($arg, $file) = @_;
  if (-f $arg && File::Spec->file_name_is_absolute ($arg)) {
    $file = $arg;
  }
  elsif ($arg =~ m/^\w+$/) {
    $file = "unicore/${arg}_alias.pl";
  }
  else {
    croak "Charnames alias files can only have identifier characters";
  }
  if (my @alias = do $file) {
    @alias == 1 && !defined $alias[0] and
      croak "$file cannot be used as alias file for charnames";
    @alias % 2 and
      croak "$file did not return a (valid) list of alias pairs";
    alias (@alias);
    return (1);
  }
  0;
} # alias_file

# For use when don't import anything.  This structure must be kept in
# sync with the one that import() fills up.
my %dummy_H = (
                charnames_stringified_names => "",
                charnames_stringified_ords => "",
                charnames_scripts => "",
                charnames_full => 1,
                charnames_loose => 0,
                charnames_short => 0,
              );


sub lookup_name ($$$) {
  my ($name, $wants_ord, $runtime) = @_;

  # Lookup the name or sequence $name in the tables.  If $wants_ord is false,
  # returns the string equivalent of $name; if true, returns the ordinal value
  # instead, but in this case $name must not be a sequence; otherwise undef is
  # returned and a warning raised.  $runtime is 0 if compiletime, otherwise
  # gives the number of stack frames to go back to get the application caller
  # info.
  # If $name is not found, returns undef in runtime with no warning; and in
  # compiletime, the Unicode replacement character, with a warning.

  # It looks first in the aliases, then in the large table of official Unicode
  # names.

  my $utf8;       # The string result
  my $save_input;

  if ($runtime) {

    my $hints_ref = (caller($runtime))[10];

    # If we didn't import anything (which happens with 'use charnames ()',
    # substitute a dummy structure.
    $hints_ref = \%dummy_H if ! defined $hints_ref
                              || (! defined $hints_ref->{charnames_full}
                                  && ! defined $hints_ref->{charnames_loose});

    # At runtime, but currently not at compile time, $^H gets
    # stringified, so un-stringify back to the original data structures.
    # These get thrown away by perl before the next invocation
    # Also fill in the hash with the non-stringified data.
    # N.B.  New fields must be also added to %dummy_H

    %{$^H{charnames_name_aliases}} = split ',',
                                      $hints_ref->{charnames_stringified_names};
    %{$^H{charnames_ord_aliases}} = split ',',
                                      $hints_ref->{charnames_stringified_ords};
    $^H{charnames_scripts} = $hints_ref->{charnames_scripts};
    $^H{charnames_full} = $hints_ref->{charnames_full};
    $^H{charnames_loose} = $hints_ref->{charnames_loose};
    $^H{charnames_short} = $hints_ref->{charnames_short};
  }

  my $loose = $^H{charnames_loose};
  my $lookup_name;  # Input name suitably modified for grepping for in the
                    # table

  # User alias should be checked first or else can't override ours, and if we
  # were to add any, could conflict with theirs.
  if (exists $^H{charnames_ord_aliases}{$name}) {
    $utf8 = $^H{charnames_ord_aliases}{$name};
  }
  elsif (exists $^H{charnames_name_aliases}{$name}) {
    $name = $^H{charnames_name_aliases}{$name};
    $save_input = $lookup_name = $name;  # Cache the result for any error
                                         # message
    # The aliases are documented to not match loosely, so change loose match
    # into full.
    if ($loose) {
      $loose = 0;
      $^H{charnames_full} = 1;
    }
  }
  else {

    # Here, not a user alias.  That means that loose matching may be in
    # effect; will have to modify the input name.
    $lookup_name = $name;
    if ($loose) {
      $lookup_name = uc $lookup_name;

      # Squeeze out all underscores
      $lookup_name =~ s/_//g;

      # Remove all medial hyphens
      $lookup_name =~ s/ (?<= \S  ) - (?= \S  )//gx;

      # Squeeze out all spaces
      $lookup_name =~ s/\s//g;
    }

    # Here, $lookup_name has been modified as necessary for looking in the
    # hashes.  Check the system alias files next.  Most of these aliases are
    # the same for both strict and loose matching.  To save space, the ones
    # which differ are in their own separate hash, which is checked if loose
    # matching is selected and the regular match fails.  To save time, the
    # loose hashes could be expanded to include all aliases, and there would
    # only have to be one check.  But if someone specifies :loose, they are
    # interested in convenience over speed, and the time for this second check
    # is miniscule compared to the rest of the routine.
    if (exists $system_aliases{$lookup_name}) {
      $utf8 = $system_aliases{$lookup_name};
    }
    elsif ($loose && exists $loose_system_aliases{$lookup_name}) {
      $utf8 = $loose_system_aliases{$lookup_name};
    }
    elsif (exists $deprecated_aliases{$lookup_name}) {
      require warnings;
      warnings::warnif('deprecated',
                       "Unicode character name \"$name\" is deprecated, use \""
                       . viacode(ord $deprecated_aliases{$lookup_name})
                       . "\" instead");
      $utf8 = $deprecated_aliases{$lookup_name};
    }
    elsif ($loose && exists $loose_deprecated_aliases{$lookup_name}) {
      require warnings;
      warnings::warnif('deprecated',
                       "Unicode character name \"$name\" is deprecated, use \""
                       . viacode(ord $loose_deprecated_aliases{$lookup_name})
                       . "\" instead");
      $utf8 = $loose_deprecated_aliases{$lookup_name};
    }
  }

  my @off;  # Offsets into table of pattern match begin and end

  # If haven't found it yet...
  if (! defined $utf8) {

    # See if has looked this input up earlier.
    if (! $loose && $^H{charnames_full} && exists $full_names_cache{$name}) {
      $utf8 = $full_names_cache{$name};
    }
    elsif ($loose && exists $loose_names_cache{$name}) {
      $utf8 = $loose_names_cache{$name};
    }
    else { # Here, must do a look-up

      # If full or loose matching succeeded, points to where to cache the
      # result
      my $cache_ref;

      ## Suck in the code/name list as a big string.
      ## Lines look like:
      ##     "00052\tLATIN CAPITAL LETTER R\n"
      # or
      #      "0052 0303\tLATIN CAPITAL LETTER R WITH TILDE\n"
      $txt = do "unicore/Name.pl" unless $txt;

      ## @off will hold the index into the code/name string of the start and
      ## end of the name as we find it.

      ## If :loose, look for a loose match; if :full, look for the name
      ## exactly
      # First, see if the name is one which is algorithmically determinable.
      # The subroutine is included in Name.pl.  The table contained in
      # $txt doesn't contain these.  Experiments show that checking
      # for these before checking for the regular names has no
      # noticeable impact on performance for the regular names, but
      # the other way around slows down finding these immensely.
      # Algorithmically determinables are not placed in the cache because
      # that uses up memory, and finding these again is fast.
      if (($loose || $^H{charnames_full})
          && (defined (my $ord = name_to_code_point_special($lookup_name, $loose))))
      {
        $utf8 = pack("U", $ord);
      }
      else {

        # Not algorithmically determinable; look up in the table.  The name
        # will be turned into a regex, so quote any meta characters.
        $lookup_name = quotemeta $lookup_name;

        if ($loose) {

          # For loose matches, $lookup_name has already squeezed out the
          # non-essential characters.  We have to add in code to make the
          # squeezed version match the non-squeezed equivalent in the table.
          # The only remaining hyphens are ones that start or end a word in
          # the original.  They have been quoted in $lookup_name so they look
          # like "\-".  Change all other characters except the backslash
          # quotes for any metacharacters, and the final character, so that
          # e.g., COLON gets transformed into: /C[- ]?O[- ]?L[- ]?O[- ]?N/
          $lookup_name =~ s/ (?! \\ -)    # Don't do this to the \- sequence
                             ( [^-\\] )   # Nor the "-" within that sequence,
                                          # nor the "\" that quotes metachars,
                                          # but otherwise put the char into $1
                             (?=.)        # And don't do it for the final char
                           /$1\[- \]?/gx; # And add an optional blank or
                                          # '-' after each $1 char

          # Those remaining hyphens were originally at the beginning or end of
          # a word, so they can match either a blank before or after, but not
          # both.  (Keep in mind that they have been quoted, so are a '\-'
          # sequence)
          $lookup_name =~ s/\\ -/(?:- | -)/xg;
        }

        # Do the lookup in the full table if asked for, and if succeeds
        # save the offsets and set where to cache the result.
        if (($loose || $^H{charnames_full}) && $txt =~ /\t$lookup_name$/m) {
          @off = ($-[0] + 1, $+[0]);    # The 1 is for the tab
          $cache_ref = ($loose) ? \%loose_names_cache : \%full_names_cache;
        }
        else {

          # Here, didn't look for, or didn't find the name.
          # If :short is allowed, see if input is like "greek:Sigma".
          # Keep in mind that $lookup_name has had the metas quoted.
          my $scripts_trie = "";
          my $name_has_uppercase;
          if (($^H{charnames_short})
              && $lookup_name =~ /^ (?: \\ \s)*   # Quoted space
                                    (.+?)         # $1 = the script
                                    (?: \\ \s)*
                                    \\ :          # Quoted colon
                                    (?: \\ \s)*
                                    (.+?)         # $2 = the name
                                    (?: \\ \s)* $
                                  /xs)
          {
              # Even in non-loose matching, the script traditionally has been
              # case insensitve
              $scripts_trie = "\U$1";
              $lookup_name = $2;

              # Use original name to find its input casing, but ignore the
              # script part of that to make the determination.
              $save_input = $name if ! defined $save_input;
              $name =~ s/.*?://;
              $name_has_uppercase = $name =~ /[[:upper:]]/;
          }
          else { # Otherwise look in allowed scripts
              $scripts_trie = $^H{charnames_scripts};

              # Use original name to find its input casing
              $name_has_uppercase = $name =~ /[[:upper:]]/;
          }

          my $case = $name_has_uppercase ? "CAPITAL" : "SMALL";
          if (! $scripts_trie
              || $txt !~
              /\t (?: $scripts_trie ) \ (?:$case\ )? LETTER \ \U$lookup_name $/xm)
          {
            # Here we still don't have it, give up.
            return if $runtime;

            # May have zapped input name, get it again.
            $name = (defined $save_input) ? $save_input : $_[0];
            carp "Unknown charname '$name'";
            return ($wants_ord) ? 0xFFFD : pack("U", 0xFFFD);
          }

          # Here have found the input name in the table.
          @off = ($-[0] + 1, $+[0]);  # The 1 is for the tab
        }

        # Here, the input name has been found; we haven't set up the output,
        # but we know where in the string
        # the name starts.  The string is set up so that for single characters
        # (and not named sequences), the name is preceded immediately by a
        # tab and 5 hex digits for its code, with a \n before those.  Named
        # sequences won't have the 7th preceding character be a \n.
        # (Actually, for the very first entry in the table this isn't strictly
        # true: subtracting 7 will yield -1, and the substr below will
        # therefore yield the very last character in the table, which should
        # also be a \n, so the statement works anyway.)
        if (substr($txt, $off[0] - 7, 1) eq "\n") {
          $utf8 = pack("U", CORE::hex substr($txt, $off[0] - 6, 5));

          # Handle the single loose matching special case, in which two names
          # differ only by a single medial hyphen.  If the original had a
          # hyphen (or more) in the right place, then it is that one.
          $utf8 = $HANGUL_JUNGSEONG_O_E_utf8
                  if $loose
                     && $utf8 eq $HANGUL_JUNGSEONG_OE_utf8
                     && $name =~ m/O \s* - [-\s]* E/ix;
                     # Note that this wouldn't work if there were a 2nd
                     # OE in the name
        }
        else {

          # Here, is a named sequence.  Need to go looking for the beginning,
          # which is just after the \n from the previous entry in the table.
          # The +1 skips past that newline, or, if the rindex() fails, to put
          # us to an offset of zero.
          my $charstart = rindex($txt, "\n", $off[0] - 7) + 1;
          $utf8 = pack("U*", map { CORE::hex }
              split " ", substr($txt, $charstart, $off[0] - $charstart - 1));
        }
      }

      # Cache the input so as to not have to search the large table
      # again, but only if it came from the one search that we cache.
      # (Haven't bothered with the pain of sorting out scoping issues for the
      # scripts searches.)
      $cache_ref->{$name} = $utf8 if defined $cache_ref;
    }
  }


  # Here, have the utf8.  If the return is to be an ord, must be any single
  # character.
  if ($wants_ord) {
    return ord($utf8) if length $utf8 == 1;
  }
  else {

    # Here, wants string output.  If utf8 is acceptable, just return what
    # we've got; otherwise attempt to convert it to non-utf8 and return that.
    my $in_bytes = ($runtime)
                   ? (caller $runtime)[8] & $bytes::hint_bits
                   : $^H & $bytes::hint_bits;
    return $utf8 if (! $in_bytes || utf8::downgrade($utf8, 1)) # The 1 arg
                                                  # means don't die on failure
  }

  # Here, there is an error:  either there are too many characters, or the
  # result string needs to be non-utf8, and at least one character requires
  # utf8.  Prefer any official name over the input one for the error message.
  if (@off) {
    $name = substr($txt, $off[0], $off[1] - $off[0]) if @off;
  }
  else {
    $name = (defined $save_input) ? $save_input : $_[0];
  }

  if ($wants_ord) {
    # Only way to get here in this case is if result too long.  Message
    # assumes that our only caller that requires single char result is
    # vianame.
    carp "charnames::vianame() doesn't handle named sequences ($name).  Use charnames::string_vianame() instead";
    return;
  }

  # Only other possible failure here is from use bytes.
  if ($runtime) {
    carp not_legal_use_bytes_msg($name, $utf8);
    return;
  } else {
    croak not_legal_use_bytes_msg($name, $utf8);
  }

} # lookup_name

sub charnames {

  # For \N{...}.  Looks up the character name and returns the string
  # representation of it.

  # The first 0 arg means wants a string returned; the second that we are in
  # compile time
  return lookup_name($_[0], 0, 0);
}

sub import
{
  shift; ## ignore class name

  if (not @_) {
    carp("`use charnames' needs explicit imports list");
  }
  $^H{charnames} = \&charnames ;
  $^H{charnames_ord_aliases} = {};
  $^H{charnames_name_aliases} = {};
  $^H{charnames_inverse_ords} = {};
  # New fields must be added to %dummy_H, and the code in lookup_name()
  # that copies fields from the runtime structure

  ##
  ## fill %h keys with our @_ args.
  ##
  my ($promote, %h, @args) = (0);
  while (my $arg = shift) {
    if ($arg eq ":alias") {
      @_ or
        croak ":alias needs an argument in charnames";
      my $alias = shift;
      if (ref $alias) {
        ref $alias eq "HASH" or
          croak "Only HASH reference supported as argument to :alias";
        alias ($alias);
        next;
      }
      if ($alias =~ m{:(\w+)$}) {
        $1 eq "full" || $1 eq "loose" || $1 eq "short" and
          croak ":alias cannot use existing pragma :$1 (reversed order?)";
        alias_file ($1) and $promote = 1;
        next;
      }
      alias_file ($alias);
      next;
    }
    if (substr($arg, 0, 1) eq ':'
      and ! ($arg eq ":full" || $arg eq ":short" || $arg eq ":loose"))
    {
      warn "unsupported special '$arg' in charnames";
      next;
    }
    push @args, $arg;
  }
  @args == 0 && $promote and @args = (":full");
  @h{@args} = (1) x @args;

  # Don't leave these undefined as are tested for in lookup_names
  $^H{charnames_full} = delete $h{':full'} || 0;
  $^H{charnames_loose} = delete $h{':loose'} || 0;
  $^H{charnames_short} = delete $h{':short'} || 0;
  my @scripts = map { uc quotemeta } keys %h;

  ##
  ## If utf8? warnings are enabled, and some scripts were given,
  ## see if at least we can find one letter from each script.
  ##
  if (warnings::enabled('utf8') && @scripts) {
    $txt = do "unicore/Name.pl" unless $txt;

    for my $script (@scripts) {
      if (not $txt =~ m/\t$script (?:CAPITAL |SMALL )?LETTER /) {
        warnings::warn('utf8',  "No such script: '$script'");
        $script = quotemeta $script;  # Escape it, for use in the re.
      }
    }
  }

  # %^H gets stringified, so serialize it ourselves so can extract the
  # real data back later.
  $^H{charnames_stringified_ords} = join ",", %{$^H{charnames_ord_aliases}};
  $^H{charnames_stringified_names} = join ",", %{$^H{charnames_name_aliases}};
  $^H{charnames_stringified_inverse_ords} = join ",", %{$^H{charnames_inverse_ords}};

  # Modify the input script names for loose name matching if that is also
  # specified, similar to the way the base character name is prepared.  They
  # don't (currently, and hopefully never will) have dashes.  These go into a
  # regex, and have already been uppercased and quotemeta'd.  Squeeze out all
  # input underscores, blanks, and dashes.  Then convert so will match a blank
  # between any characters.
  if ($^H{charnames_loose}) {
    for (my $i = 0; $i < @scripts; $i++) {
      $scripts[$i] =~ s/[_ -]//g;
      $scripts[$i] =~ s/ ( [^\\] ) (?= . ) /$1\\ ?/gx;
    }
  }

  $^H{charnames_scripts} = join "|", @scripts;  # Stringifiy them as a trie
} # import

# Cache of already looked-up values.  This is set to only contain
# official values, and user aliases can't override them, so scoping is
# not an issue.
my %viacode;

sub viacode {

  # Returns the name of the code point argument

  if (@_ != 1) {
    carp "charnames::viacode() expects one argument";
    return;
  }

  my $arg = shift;

  # This is derived from Unicode::UCD, where it is nearly the same as the
  # function _getcode(), but here it makes sure that even a hex argument
  # has the proper number of leading zeros, which is critical in
  # matching against $txt below
  # Must check if decimal first; see comments at that definition
  my $hex;
  if ($arg =~ $decimal_qr) {
    $hex = sprintf "%05X", $arg;
  } elsif ($arg =~ $hex_qr) {
    # Below is the line that differs from the _getcode() source
    $hex = sprintf "%05X", hex $1;
  } else {
    carp("unexpected arg \"$arg\" to charnames::viacode()");
    return;
  }

  return $viacode{$hex} if exists $viacode{$hex};

  # If the code point is above the max in the table, there's no point
  # looking through it.  Checking the length first is slightly faster
  if (length($hex) <= 5 || CORE::hex($hex) <= 0x10FFFF) {
    $txt = do "unicore/Name.pl" unless $txt;

    # See if the name is algorithmically determinable.
    my $algorithmic = code_point_to_name_special(CORE::hex $hex);
    if (defined $algorithmic) {
      $viacode{$hex} = $algorithmic;
      return $algorithmic;
    }

    # Return the official name, if exists.  It's unclear to me (khw) at
    # this juncture if it is better to return a user-defined override, so
    # leaving it as is for now.
    if ($txt =~ m/^$hex\t/m) {

        # The name starts with the next character and goes up to the
        # next new-line.  Using capturing parentheses above instead of
        # @+ more than doubles the execution time in Perl 5.13
        $viacode{$hex} = substr($txt, $+[0], index($txt, "\n", $+[0]) - $+[0]);
        return $viacode{$hex};
    }
  }

  # See if there is a user name for it, before giving up completely.
  # First get the scoped aliases, give up if have none.
  my $H_ref = (caller(0))[10];
  return if ! defined $H_ref
            || ! exists $H_ref->{charnames_stringified_inverse_ords};

  my %code_point_aliases = split ',',
                          $H_ref->{charnames_stringified_inverse_ords};
  if (! exists $code_point_aliases{$hex}) {
    if (CORE::hex($hex) > 0x10FFFF) {
        carp "Unicode characters only allocated up to U+10FFFF (you asked for U+$hex)";
    }
    return;
  }

  return $code_point_aliases{$hex};
} # viacode

sub vianame
{
  if (@_ != 1) {
    carp "charnames::vianame() expects one name argument";
    return ()
  }

  # Looks up the character name and returns its ordinal if
  # found, undef otherwise.

  my $arg = shift;

  if ($arg =~ /^U\+([0-9a-fA-F]+)$/) {

    # khw claims that this is poor interface design.  The function should
    # return either a an ord or a chr for all inputs; not be bipolar.  But
    # can't change it because of backward compatibility.  New code can use
    # string_vianame() instead.
    my $ord = CORE::hex $1;
    return chr $ord if $ord <= 255 || ! ((caller 0)[8] & $bytes::hint_bits);
    carp not_legal_use_bytes_msg($arg, chr $ord);
    return;
  }

  # The first 1 arg means wants an ord returned; the second that we are in
  # runtime, and this is the first level routine called from the user
  return lookup_name($arg, 1, 1);
} # vianame

sub string_vianame {

  # Looks up the character name and returns its string representation if
  # found, undef otherwise.

  if (@_ != 1) {
    carp "charnames::string_vianame() expects one name argument";
    return;
  }

  my $arg = shift;

  if ($arg =~ /^U\+([0-9a-fA-F]+)$/) {

    my $ord = CORE::hex $1;
    return chr $ord if $ord <= 255 || ! ((caller 0)[8] & $bytes::hint_bits);

    carp not_legal_use_bytes_msg($arg, chr $ord);
    return;
  }

  # The 0 arg means wants a string returned; the 1 arg means that we are in
  # runtime, and this is the first level routine called from the user
  return lookup_name($arg, 0, 1);
} # string_vianame



1;
__END__

=head1 NAME

charnames - access to Unicode character names and named character sequences; also define character names

=head1 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 ':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 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"

=head1 DESCRIPTION

Pragma C<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:

=over

=item *

L</charnames::string_vianame(I<name>)> for run-time lookup of a
either a character name or a named character sequence, returning its string
representation

=item *

L</charnames::vianame(I<name>)> for run-time lookup of a
character name (but not a named character sequence) to get its ordinal value
(code point)

=item *

L</charnames::viacode(I<code>)> for run-time lookup of a code point to get its
Unicode name.

=back

All forms other than C<S<"use charnames ();">> also enable the use of
C<\N{I<CHARNAME>}> sequences to compile a Unicode character into a
string, based on its name.

Note that C<\N{U+I<...>}>, where the I<...> 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, C<"\N{U+263a}"> is
the Unicode (white background, black foreground) smiley face; it doesn't
require this pragma, whereas the equivalent, C<"\N{WHITE SMILING FACE}">
does.
Also, C<\N{I<...>}> can mean a regex quantifier instead of a character
name, when the I<...> is a number (or comma separated pair of numbers
(see L<perlreref/QUANTIFIERS>), and is not related to this pragma.

The C<charnames> pragma supports arguments C<:full>, C<:loose>, C<:short>,
script names and L<customized aliases|/CUSTOM ALIASES>.

If C<:full> is present, for expansion of
C<\N{I<CHARNAME>}>, the string I<CHARNAME> is first looked up in the list of
standard Unicode character names.

C<:loose> is a variant of C<:full> which allows I<CHARNAME> to be less
precisely specified.  Details are in L</LOOSE MATCHES>.

If C<:short> is present, and
I<CHARNAME> has the form C<I<SCRIPT>:I<CNAME>>, then I<CNAME> is looked up
as a letter in script I<SCRIPT>, as described in the next paragraph.
Or, if C<use charnames> is used
with script name arguments, then for C<\N{I<CHARNAME>}> the name
I<CHARNAME> is looked up as a letter in the given scripts (in the
specified order). Customized aliases can override these, and are explained in
L</CUSTOM ALIASES>.

For lookup of I<CHARNAME> inside a given script I<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 I<CHARNAME> is all lowercase,
then the C<CAPITAL> variant is ignored, otherwise the C<SMALL> variant
is ignored, and both I<CHARNAME> and I<SCRIPTNAME> are converted to all
uppercase for look-up.  Other than that, both of them follow L<loose|/LOOSE
MATCHES> rules if C<:loose> is also specified; strict otherwise.

Note that C<\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 C<\N{...}>.  If you want similar run-time
functionality, use
L<charnames::string_vianame()|/charnames::string_vianame(I<name>)>.

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 L</ALIASES>.  Since Unicode 6.0, it
is deprecated to use C<BELL>.  Instead use C<ALERT> (but C<BEL> works).

If the input name is unknown, C<\N{NAME}> raises a warning and
substitutes the Unicode REPLACEMENT CHARACTER (U+FFFD).

For C<\N{NAME}>, it is a fatal error if C<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 C<\N{I<charname>}> or
C<S<\N{U+I<code point>}>> will automatically have Unicode semantics (see
L<perlunicode/Byte and Character Semantics>).

=head1 LOOSE MATCHES

By specifying C<:loose>, Unicode's L<loose character name
matching|http://www.unicode.org/reports/tr44#Matching_Rules> rules are
selected instead of the strict exact match used otherwise.
That means that I<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 C<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 C<TIBETAN LETTER -A> versus U+0F68 C<TIBETAN LETTER A>.
The hyphen here is significant, as is the space before it, and so both must be
included.

C<:loose> slows down look-ups by a factor of 2 to 3 versus
C<: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 C<\N{...}> look-ups are done at compile time.

=head1 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 C<ACK> for
C<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

=head1 CUSTOM ALIASES

You can add customized aliases to standard (C<:full>) Unicode naming
conventions.  The aliases override any standard definitions, so, if
you're twisted enough, you can change C<"\N{LATIN CAPITAL LETTER A}"> to
mean C<"B">, etc.

Note that an alias should not be something that is a legal curly
brace-enclosed quantifier (see L<perlreref/QUANTIFIERS>).  For example
C<\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 (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 C<"U+"> or C<"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 C<"unicore/pro_alias.pl"> from the C<@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 C<":full"> automatically as the first argument (if no
other argument is given), and you can give the C<":full"> explicitly as
well, like

    use charnames ":full", ":alias" => "pro";

C<":loose"> has no effect with these.  Input names must match exactly, using
C<":full"> rules.

Also, both these methods currently allow only single characters to be named.
To name a sequence of characters, use a
L<custom translator|/CUSTOM TRANSLATORS> (described below).

=head1 charnames::viacode(I<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 a 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 C<undef> if no name is known for the code point.
In Unicode the proper name of these is the empty string, which
C<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 C<undef> plus a warning.)

The input number must be a non-negative integer or a string beginning
with C<"U+"> or C<"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".

=head1 charnames::string_vianame(I<name>)

This is a runtime equivalent to C<\N{...}>.  I<name> can be any expression
that evaluates to a name accepted by C<\N{...}> under the L<C<:full>
option|/DESCRIPTION> to C<charnames>.  In addition, any other options for the
controlling C<"use charnames"> in the same scope apply, like C<:loose> or any
L<script list, C<:short> option|/DESCRIPTION>, or L<custom aliases|/CUSTOM
ALIASES> you may have defined.

The only difference is that if the input name is unknown, C<string_vianame>
returns C<undef> instead of the REPLACEMENT CHARACTER and does not raise a
warning message.

=head1 charnames::vianame(I<name>)

This is similar to C<string_vianame>.  The main difference is that under most
circumstances, vianame returns an ordinal code
point, whereas C<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 C<undef> for these.  And, the code
point can be that of any
character, even ones that aren't legal under the C<S<use bytes>> pragma,

See L</BUGS> for the circumstances in which the behavior differs
from  that described above.

=head1 CUSTOM TRANSLATORS

The mechanism of translation of C<\N{...}> escapes is general and not
hardwired into F<charnames.pm>.  A module can install custom
translations (inside the scope which C<use>s the module) with the
following magic incantation:

    sub import {
        shift;
        $^H{charnames} = \&translator;
    }

Here translator() is a subroutine which takes I<CHARNAME> as an
argument, and returns text to insert into the string instead of the
C<\N{I<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 C<bytes> mode and out of it, the function should check the current
state of C<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 L</CUSTOM ALIASES> above for restrictions on I<CHARNAME>.

Of course, C<vianame>, C<viacode>, and C<string_vianame> would need to be
overridden as well.

=head1 BUGS

vianame() normally returns an ordinal code point, but when the input name is of
the form C<U+...>, it returns a chr instead.  In this case, if C<use bytes> is
in effect and the character won't fit into a byte, it returns C<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 L</CUSTOM
TRANSLATORS>) happens in the middle of compilation (of a string
literal), the translation function should not do any C<eval>s or
C<require>s.  This restriction should be lifted (but is low priority) in
a future version of Perl.

=cut

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