charnames - define character names for C<\N{named}> string literal escapes |
charnames - define character names for \N{named}
string literal escapes
use charnames ':full'; print "\N{GREEK SMALL LETTER SIGMA} is called sigma.\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";
print charnames::viacode(0x1234); # prints "ETHIOPIC SYLLABLE SEE" printf "%04X", charnames::vianame("GOTHIC LETTER AHSA"); # prints "10330"
Pragma use charnames
supports arguments :full
, :short
and
script names. If :full
is present, for expansion of
\N{CHARNAME}
string CHARNAME
is first looked in the list of
standard Unicode names of chars. If :short
is present, and
CHARNAME
has the form SCRIPT:CNAME
, then CNAME
is looked up
as a letter in script SCRIPT
. If pragma 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).
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-quoted strings: in other words, you cannot
use variables inside the \N{...}
. If you want similar run-time
functionality, use charnames::vianame().
For the C0 and C1 control characters (U+0000..U+001F, U+0080..U+009F) as of Unicode 3.1, there are no official Unicode names but you can use instead the ISO 6429 names (LINE FEED, ESCAPE, and so forth). In Unicode 3.2 (as of Perl 5.8) some naming changes take place ISO 6429 has been updated, see ALIASES. Also note that the U+UU80, U+0081, U+0084, and U+0099 do not have names even in ISO 6429.
Since the Unicode standard uses ``U+HHHH'', so can you: ``\N{U+263a}'' is the Unicode smiley face, or ``\N{WHITE SMILING FACE}''.
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:
use charnames (); # for $charnames::hint_bits sub import { shift; $^H |= $charnames::hint_bits; $^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(@_); } }
Returns the full name of the character indicated by the numeric code. The example
print charnames::viacode(0x2722);
prints ``FOUR TEARDROP-SPOKED ASTERISK''.
Returns undef if no name is known for the code.
This works only for the standard names, and does not yet apply to custom translators.
Notice that the name returned for of U+FEFF is ``ZERO WIDTH NO-BREAK SPACE'', not ``BYTE ORDER MARK''.
Returns the code point indicated by the name. The example
printf "%04X", charnames::vianame("FOUR TEARDROP-SPOKED ASTERISK");
prints ``2722''.
Returns undef if the name is unknown.
This works only for the standard names, and does not yet apply to custom translators.
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
One can also use
BYTE ORDER MARK BOM
and
ZWNJ ZWJ
for ZERO WIDTH NON-JOINER and ZERO WIDTH JOINER.
For backward compatibility one can use the old names for certain C0 and C1 controls
old new
HORIZONTAL TABULATION CHARACTER TABULATION VERTICAL TABULATION LINE TABULATION FILE SEPARATOR INFORMATION SEPARATOR FOUR GROUP SEPARATOR INFORMATION SEPARATOR THREE RECORD SEPARATOR INFORMATION SEPARATOR TWO UNIT SEPARATOR INFORMATION SEPARATOR ONE PARTIAL LINE DOWN PARTIAL LINE FORWARD PARTIAL LINE UP PARTIAL LINE BACKWARD
but the old names in addition to giving the character will also give a warning about being deprecated.
If you ask by name for a character that does not exist, a warning is given and the Unicode replacement character ``\x{FFFD}'' is returned.
If you ask by code for a character that does not exist, no warning is
given and undef
is returned. (Though if you ask for a code point
past U+10FFFF you do get a warning.)
Since evaluation of the translation function happens in a middle of
compilation (of a string literal), the translation function should not
do any eval
s or require
s. This restriction should be lifted in
a future version of Perl.
charnames - define character names for C<\N{named}> string literal escapes |