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NAME
Unicode::String - String of Unicode characters (UTF-16BE)
SYNOPSIS
use Unicode::String qw(utf8 latin1 utf16be);
$u = utf8("string");
$u = latin1("string");
$u = utf16be("\0s\0t\0r\0i\0n\0g");
print $u->utf32be; # 4 byte characters
print $u->utf16le; # 2 byte characters + surrogates
print $u->utf8; # 1-4 byte characters
DESCRIPTION
A "Unicode::String" object represents a sequence of Unicode characters.
Methods are provided to convert between various external formats
(encodings) and "Unicode::String" objects, and methods are provided for
common string manipulations.
The functions utf32be(), utf32le(), utf16be(), utf16le(), utf8(),
utf7(), latin1(), uhex(), uchr() can be imported from the
"Unicode::String" module and will work as constructors initializing
strings of the corresponding encoding.
The "Unicode::String" objects overload various operators, which means
that they in most cases can be treated like plain strings.
Internally a "Unicode::String" object is represented by a string of 2
byte numbers in network byte order (big-endian). This representation is
not visible by the API provided, but it might be useful to know in order
to predict the efficiency of the provided methods.
METHODS
Class methods
The following class methods are available:
Unicode::String->stringify_as
Unicode::String->stringify_as( $enc )
This method is used to specify which encoding will be used when
"Unicode::String" objects are implicitly converted to and from plain
strings.
If an argument is provided it sets the current encoding. The
argument should have one of the following: "ucs4", "utf32",
"utf32be", "utf32le", "ucs2", "utf16", "utf16be", "utf16le", "utf8",
"utf7", "latin1" or "hex". The default is "utf8".
The stringify_as() method returns a reference to the current
encoding function.
$us = Unicode::String->new
$us = Unicode::String->new( $initial_value )
This is the object constructor. Without argument, it creates an
empty "Unicode::String" object. If an $initial_value argument is
given, it is decoded according to the specified stringify_as()
encoding, UTF-8 by default.
In general it is recommended to import and use one of the encoding
specific constructor functions instead of invoking this method.
Encoding methods
þÿ T h e s e m e t h o d s g e t o r s e t t h e v a l u e o f t h e " U n i c o d e : : S t r i n g " o b j e c t b y
p a s s i n g s t r i n g s i n t h e c o r r e s p o n d i n g e n c o d i n g . I f a n e w v a l u e i s p a s s e d
a s a r g u m e n t i t w i l l s e t t h e v a l u e o f t h e " U n i c o d e : : S t r i n g " , a n d t h e
p r e v i o u s v a l u e i s r e t u r n e d . I f n o a r g u m e n t i s p a s s e d t h e n t h e c u r r e n t
v a l u e i s r e t u r n e d .
To illustrate the encodings we show how the 2 character sample strin of "µm" (micro meter) is encoded for each one.
=over
=item $us->utf32be
=item $us->utf32be( $newval
The string passed should be in the UTF-32 encoding with bytes in big endian order. The sample "µm" is "\0\0\0\xB5\0\0\0m" in this encoding
Alternative names for this method are utf32() and ucs4()
=item $us->utf32le
=item $us->utf32le( $newval
The string passed should be in the UTF-32 encoding with bytes in littl
endian order. The sample "µm" is is "\xB5\0\0\0m\0\0\0" in this encoding.
=item $us->utf16be
=item $us->utf16be( $newval
The string passed should be in the UTF-16 encoding with bytes in big endian order. The sample "µm" is "\0\xB5\0m" in this encoding.
Alternative names for this method are utf16() and ucs2()
If the string passed to utf16be() starts with the Unicode byte order mark in little endian order, the result is as if utf16le() was calle
instead.
=item $us->utf16le
=item $us->utf16le( $newval
The string passed should be in the UTF-16 encoding with bytes in little endian order. The sample "µm" is is "\xB5\0m\0" in thi
encoding. This is the encoding used by the Microsoft Windows API.
If the string passed to utf16le() starts with the Unicode byte order mark in big endian order, the result is as if utf16le() was called
instead.
=item $us->utf
=item $us->utf8( $newval
The string passed should be in the UTF-8 encoding. The sample "µm" i "\xC2\xB5m" in this encoding
=item $us->utf
=item $us->utf7( $newval
The string passed should be in the UTF-7 encoding. The sample "µm" i "+ALU-m" in this encoding.
The UTF-7 encoding only use plain US-ASCII characters for th encoding. This makes it safe for transport through 8-bit strippin
protocols. Characters outside the US-ASCII range are base64-encoded and '+' is used as an escape character. The UTF-7 encoding is
described in RFC 1642.
If the (global) variable $Unicode::String::UTF7_OPTIONAL_DIRECT_CHAR is TRUE, then a wider range of characters are encoded as themselves.
It is even TRUE by default. The characters affected by this are
! " # $ % & * ; < = > @ [ ] ^ _ ` { | }
=item $us->latin
=item $us->latin1( $newval
The string passed should be in the ISO-8859-1 encoding. The sample "µm" is "\xB5m" in this encoding
Characters outside the "\x00" .. "\xFF" range are simply removed fro the return value of the latin1() method. If you want more control
over the mapping from Unicode to ISO-8859-1, use the C<Unicode::Map8 class. This is also the way to deal with other 8-bit character sets
=item $us->hex
=item $us->hex( $newval
The string passed should be plain ASCII where each Unicode character is represented by the "U+XXXX" string and separated by a single spac
character. The "U+" prefix is optional when setting the value. The sample "µm" is "U+00b5 U+006d" in this encoding.
=bac
=head2 String Operations
The following methods are available:
=over
=item $us->as_string
Converts a C<Unicode::String> to a plain string according to the setting of stringify_as(). The default stringify_as() encoding is "utf8"
=item $us->as_nu
Converts a C<Unicode::String> to a number. Currently only the digit in the range 0x30 .. 0x39 are recognized. The plan is to eventually
support all Unicode digit characters
=item $us->as_bool
Converts a C<Unicode::String> to a boolean value. Only the empt string is FALSE. A string consisting of only the character U+0030 i
considered TRUE, even if Perl consider "0" to be FALSE
=item $us->repeat( $count
Returns a new C<Unicode::String> where the content of $us is repeate $count times. This operation is also overloaded as:
$us x $count
=item $us->concat( $other_string
Concatenates the string $us and the string $other_string. I $other_string is not an C<Unicode::String> object, then it is firs
passed to the Unicode::String->new constructor function. This operation is also overloaded as:
$us . $other_strin
=item $us->append( $other_string
Appends the string $other_string to the value of $us. I $other_string is not an C<Unicode::String> object, then it is firs
passed to the Unicode::String->new constructor function. This operation is also overloaded as:
$us .= $other_string
=item $us->cop
Returns a copy of the current C<Unicode::String> object. This operation is overloaded as the assignment operator
=item $us->lengt
Returns the length of the C<Unicode::String>. Surrogate pairs are still counted as 2
=item $us->byteswa
This method will swap the bytes in the internal representation of th C<Unicode::String> object.
Unicode reserve the character U+FEFF character as a byte order mark. This works because the swapped character, U+FFFE, is reserved to not
be valid. For strings that have the byte order mark as the firs character, we can guaranty to get the byte order right with th following code
$ustr->byteswap if $ustr->ord == 0xFFFE
=item $us->unpac
Returns a list of integers each representing an UCS-2 character code
=item $us->pack( @uchr
Sets the value of $us as a sequence of UCS-2 characters with the characters codes given as parameter.
=item $us->ord
Returns the character code of the first character in $us. The ord() method deals with surrogate pairs, which gives us a result-range o
0x0 .. 0x10FFFF. If the $us string is empty, undef is returned.
=item $us->chr( $code
Sets the value of $us to be a string containing the character assigned code $code. The argument $code must be an integer in the range 0x
.. 0x10FFFF. If the code is greater than 0xFFFF then a surrogate pair created.
=item $us->nam
In scalar context returns the official Unicode name of the first character in $us. In array context returns the name of all characters
in $us. Also see L<Unicode::CharName>
=item $us->substr( $offset
=item $us->substr( $offset, $length
=item $us->substr( $offset, $length, $subst
Returns a sub-string of $us. Works similar to the builtin substr( function
=item $us->index( $other
=item $us->index( $other, $pos
Locates the position of $other within $us, possibly starting the search at position $pos.
=item $us->cho
Chops off the last character of $us and returns it (as a C<Unicode::String> object)
=bac
=head1 FUNCTIONS
The following functions are provided. None of these are exported by default
=over
=item byteswap2( $str, ...
This function will swap 2 and 2 bytes in the strings passed as arguments. If this function is called in void context
then it will modify its arguments in-place. Otherwise, the swappe strings are returned
=item byteswap4( $str, ...
The byteswap4 function works similar to byteswap2, but will revers the order of 4 and 4 bytes
=item latin1( $str
=item utf7( $str
=item utf8( $str
=item utf16le( $str
=item utf16be( $str
=item utf32le( $str
=item utf32be( $str
Constructor functions for the various Unicode encodings. These return new C<Unicode::String> objects. The provided argument should be
encoded correspondingly.
=item uhex( $str
Constructs a new C<Unicode::String> object from a string of he values. See hex() method above for description of the format.
=item uchar( $num
Constructs a new one character C<Unicode::String> object from Unicode character code. This works similar to perl's builtin chr( function
=bac
=head1 SEE ALS
L<Unicode::CharName> L<Unicode::Map8>
L<http://www.unicode.org/>
L<perlunicode>
=head1 COPYRIGHT
Copyright 1997-2000,2005 Gisle Aas
This library is free software; you can redistribute it and/o modify it under the same terms as Perl itself.
=cut
# Some old code that is not used any more (because the methods are # now implemented as XS) and which I did not want to throw away yet.
sub ucs4_inper
my $self = shift unless (ref $self) { my $u = new Unicode::String $u->ucs4($self) return $u
my $old = pack("N*", $self->ord) if (@_) $$self = "" for (unpack("N*", shift)) { $self->append(uchr($_)) } $old
sub utf8_inper
my $self = shift unless (ref $self) { # act as ctor my $u = new Unicode::String $u->utf8($self) return $u
my $old; if (defined($$self) && defined wantarray) # encode UTF- my $uc; for $uc (unpack("n*", $$self)) if ($uc < 0x80) {
# 1 byte representatio $old .= chr($uc) } elsif ($uc < 0x800) { # 2 byte representatio $old .= chr(0xC0 | ($uc >> 6)) .
chr(0x80 | ($uc & 0x3F)) } else # 3 byte representatio $old .= chr(0xE0 | ($uc >> 12))
chr(0x80 | (($uc >> 6) & 0x3F)) chr(0x80 | ($uc & 0x3F)); } }
if (@_) if (defined $_[0]) $$self = "" my $bytes = shift $bytes =~ s/^[\200-\277]+//; # can't start with 10xxxxxx
while (length $bytes) { if ($bytes =~ s/^([\000-\177]+)//) { $$self .= pack("n*", unpack("C*", $1))
} elsif ($bytes =~ s/^([\300-\337])([\200-\277])//) my($b1,$b2) = (ord($1), ord($2))
$$self .= pack("n", (($b1 & 0x1F) << 6) | ($b2 & 0x3F)); } elsif ($bytes =~ s/^([\340-\357])([\200-\277])([\200-\277])//) {
my($b1,$b2,$b3) = (ord($1), ord($2), ord($3)); $$self .= pack("n", (($b1 & 0x0F) << 12) |
(($b2 & 0x3F) << 6) | ($b3 & 0x3F)) } else { croak "Bad UTF-8 data" }
} else $$self = undef; }
$old
sub latin1_inper
my $self = shift unless (ref $self) { # act as ctor my $u = new Unicode::String $u->latin1($self) return $u
my $old; # XXX: should really check that none of the chars > 25 $old = pack("C*", unpack("n*", $$self)) if defined $$self;
if (@_) # set the value if (defined $_[0]) $$self = pack("n*", unpack("C*", $_[0])); } else $$self = undef; }
$old
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