package bytes;
our $VERSION = '1.03';
BEGIN {
$bytes::hint_bits = 0x00000008;
$bytes::codepoints_hint_bits = 0x01000000;
}
sub import {
$^HINT_BITS ^|^= $bytes::hint_bits;
$^HINT_BITS ^&^= ^~^$bytes::codepoints_hint_bits;
}
sub unimport {
$^HINT_BITS ^&^= ^~^$bytes::hint_bits;
}
BEGIN { bytes::import() }
sub length ($s) {
return CORE::length($s);
}
sub substr {
return
(nelems @_) == 2 ?? CORE::substr(@_[0], @_[1]) !!
(nelems @_) == 3 ?? CORE::substr(@_[0], @_[1], @_[2]) !!
CORE::substr(@_[0], @_[1], @_[2], @_[3]) ;
}
sub ord($s) {
return CORE::ord($s);
}
sub chr($s) {
return CORE::chr($s);
}
sub index {
return
(nelems @_) == 2 ?? CORE::index(@_[0], @_[1]) !!
CORE::index(@_[0], @_[1], @_[2]) ;
}
sub rindex {
return
(nelems @_) == 2 ?? CORE::rindex(@_[0], @_[1]) !!
CORE::rindex(@_[0], @_[1], @_[2]) ;
}
BEGIN { bytes::import() }
1;
__END__
=head1 NAME
bytes - Perl pragma to force byte semantics rather than character semantics
=head1 SYNOPSIS
use bytes;
... chr(...); # or bytes::chr
... index(...); # or bytes::index
... length(...); # or bytes::length
... ord(...); # or bytes::ord
... rindex(...); # or bytes::rindex
... substr(...); # or bytes::substr
no bytes;
=head1 DESCRIPTION
The C<use bytes> pragma disables character semantics for the rest of the
lexical scope in which it appears. C<no bytes> can be used to reverse
the effect of C<use bytes> within the current lexical scope.
Perl normally assumes character semantics in the presence of character
data (i.e. data that has come from a source that has been marked as
being of a particular character encoding). When C<use bytes> is in
effect, the encoding is temporarily ignored, and each string is treated
as a series of bytes.
As an example, when Perl sees C<$x = chr(400)>, it encodes the character
in UTF-8 and stores it in $x. Then it is marked as character data, so,
for instance, C<length $x> returns C<1>. However, in the scope of the
C<bytes> pragma, $x is treated as a series of bytes - the bytes that make
up the UTF8 encoding - and C<length $x> returns C<2>:
$x = chr(400);
print "Length is ", length $x, "\n"; # "Length is 1"
printf "Contents are %vd\n", $x; # "Contents are 400"
{
use bytes; # or "require bytes; bytes::length()"
print "Length is ", length $x, "\n"; # "Length is 2"
printf "Contents are %vd\n", $x; # "Contents are 198.144"
}
chr(), ord(), substr(), index() and rindex() behave similarly.
For more on the implications and differences between character
semantics and byte semantics, see L<perluniintro> and L<perlunicode>.
=head1 LIMITATIONS
bytes::substr() does not work as an lvalue().
=head1 SEE ALSO
L<perluniintro>, L<perlunicode>, L<utf8>
=cut