#
-# $Id: Encode.pm,v 1.63 2002/04/27 18:59:50 dankogai Exp $
+# $Id: Encode.pm,v 1.75 2002/06/01 18:07:42 dankogai Exp $
#
package Encode;
use strict;
-our $VERSION = do { my @r = (q$Revision: 1.63 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
+our $VERSION = do { my @r = (q$Revision: 1.75 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
our $DEBUG = 0;
use XSLoader ();
XSLoader::load(__PACKAGE__, $VERSION);
encodings find_encoding
);
-our @FB_FLAGS = qw(DIE_ON_ERR WARN_ON_ERR RETURN_ON_ERR LEAVE_SRC
+our @FB_FLAGS = qw(DIE_ON_ERR WARN_ON_ERR RETURN_ON_ERR LEAVE_SRC
PERLQQ HTMLCREF XMLCREF);
-our @FB_CONSTS = qw(FB_DEFAULT FB_CROAK FB_QUIET FB_WARN
+our @FB_CONSTS = qw(FB_DEFAULT FB_CROAK FB_QUIET FB_WARN
FB_PERLQQ FB_HTMLCREF FB_XMLCREF);
our @EXPORT_OK =
sub encode($$;$)
{
- my ($name,$string,$check) = @_;
+ my ($name, $string, $check) = @_;
$check ||=0;
my $enc = find_encoding($name);
unless(defined $enc){
$_[1] = '' if $chk;
return $octets;
};
- $Encode::Encoding{utf8} =
+ $Encode::Encoding{utf8} =
bless {Name => "utf8"} => "Encode::utf8";
}
}
=back
-The marker [INTERNAL] marks Internal Implementation Details, in
-general meant only for those who think they know what they are doing,
-and such details may change in future releases.
-
=head1 PERL ENCODING API
=over 2
-=item $octets = encode(ENCODING, $string[, CHECK])
+=item $octets = encode(ENCODING, $string [, CHECK])
Encodes a string from Perl's internal form into I<ENCODING> and returns
a sequence of octets. ENCODING can be either a canonical name or
an alias. For encoding names and aliases, see L</"Defining Aliases">.
For CHECK, see L</"Handling Malformed Data">.
-For example, to convert (internally UTF-8 encoded) Unicode string to
+For example, to convert a string from Perl's internal format to
iso-8859-1 (also known as Latin1),
- $octets = encode("iso-8859-1", $utf8);
+ $octets = encode("iso-8859-1", $string);
-B<CAVEAT>: When you C<$octets = encode("utf8", $utf8)>, then $octets
-B<ne> $utf8. Though they both contain the same data, the utf8 flag
+B<CAVEAT>: When you run C<$octets = encode("utf8", $string)>, then $octets
+B<may not be equal to> $string. Though they both contain the same data, the utf8 flag
for $octets is B<always> off. When you encode anything, utf8 flag of
the result is always off, even when it contains completely valid utf8
string. See L</"The UTF-8 flag"> below.
-=item $string = decode(ENCODING, $octets[, CHECK])
+encode($valid_encoding, undef) is harmless but warns you for
+C<Use of uninitialized value in subroutine entry>.
+encode($valid_encoding, '') is harmless and warnless.
+
+=item $string = decode(ENCODING, $octets [, CHECK])
Decodes a sequence of octets assumed to be in I<ENCODING> into Perl's
internal form and returns the resulting string. As in encode(),
and aliases, see L</"Defining Aliases">. For CHECK, see
L</"Handling Malformed Data">.
-For example, to convert ISO-8859-1 data to UTF-8:
+For example, to convert ISO-8859-1 data to a string in Perl's internal format:
- $utf8 = decode("iso-8859-1", $latin1);
+ $string = decode("iso-8859-1", $octets);
-B<CAVEAT>: When you C<$utf8 = encode("utf8", $octets)>, then $utf8
-B<may not be equal to> $utf8. Though they both contain the same data,
-the utf8 flag for $utf8 is on unless $octets entirely conststs of
+B<CAVEAT>: When you run C<$string = decode("utf8", $octets)>, then $string
+B<may not be equal to> $octets. Though they both contain the same data,
+the utf8 flag for $string is on unless $octets entirely consists of
ASCII data (or EBCDIC on EBCDIC machines). See L</"The UTF-8 flag">
below.
-=item [$length =] from_to($string, FROM_ENC, TO_ENC [, CHECK])
+decode($valid_encoding, undef) is harmless but warns you for
+C<Use of uninitialized value in subroutine entry>.
+decode($valid_encoding, '') is harmless and warnless.
+
+=item [$length =] from_to($octets, FROM_ENC, TO_ENC [, CHECK])
-Converts B<in-place> data between two encodings. For example, to
-convert ISO-8859-1 data to UTF-8:
+Converts B<in-place> data between two encodings. The data in $octets
+must be encoded as octets and not as characters in Perl's internal
+format. For example, to convert ISO-8859-1 data to Microsoft's CP1250 encoding:
- from_to($data, "iso-8859-1", "utf8");
+ from_to($octets, "iso-8859-1", "cp1250");
and to convert it back:
- from_to($data, "utf8", "iso-8859-1");
+ from_to($octets, "cp1250", "iso-8859-1");
Note that because the conversion happens in place, the data to be
converted cannot be a string constant; it must be a scalar variable.
-from_to() returns the length of the converted string on success, undef
+from_to() returns the length of the converted string in octets on success, undef
otherwise.
-B<CAVEAT>: The following operations look the same but not quite so;
+B<CAVEAT>: The following operations look the same but are not quite so;
- from_to($data, "iso-8859-1", "utf8"); #1
+ from_to($data, "iso-8859-1", "utf8"); #1
$data = decode("iso-8859-1", $data); #2
-Both #1 and #2 makes $data consists of completely valid UTF-8 string
+Both #1 and #2 make $data consist of a completely valid UTF-8 string
but only #2 turns utf8 flag on. #1 is equivalent to
$data = encode("utf8", decode("iso-8859-1", $data));
=item $octets = encode_utf8($string);
Equivalent to C<$octets = encode("utf8", $string);> The characters
-that comprise $string are encoded in Perl's superset of UTF-8 and the
-resulting octets are returned as a sequence of bytes. All possible
+that comprise $string are encoded in Perl's internal format and the
+result is returned as a sequence of octets. All possible
characters have a UTF-8 representation so this function cannot fail.
=item $string = decode_utf8($octets [, CHECK]);
equivalent to C<$string = decode("utf8", $octets [, CHECK])>.
-decode_utf8($octets [, CHECK]); The sequence of octets represented by
+The sequence of octets represented by
$octets is decoded from UTF-8 into a sequence of logical
characters. Not all sequences of octets form valid UTF-8 encodings, so
it is possible for this call to fail. For CHECK, see
=head1 Encoding via PerlIO
-If your perl supports I<PerlIO>, you can use a PerlIO layer to decode
+If your perl supports I<PerlIO> (which is the default), you can use a PerlIO layer to decode
and encode directly via a filehandle. The following two examples
are totally identical in their functionality.
# via PerlIO
open my $in, "<:encoding(shiftjis)", $infile or die;
open my $out, ">:encoding(euc-jp)", $outfile or die;
- while(<>){ print; }
+ while(<$in>){ print $out $_; }
# via from_to
open my $in, "<", $infile or die;
open my $out, ">", $outfile or die;
- while(<>){
+ while(<$in>){
from_to($_, "shiftjis", "euc-jp", 1);
+ print $out $_;
}
-Unfortunately, there may be encodings are PerlIO-savvy. You can check
+Unfortunately, it may be that encodings are PerlIO-savvy. You can check
if your encoding is supported by PerlIO by calling the C<perlio_ok>
method.
perlio_ok("euc-jp")
Fortunately, all encodings that come with Encode core are PerlIO-savvy
-except for hz and ISO-2022-kr. See L<Encode::Encoding> for details.
-
-For gory details, see L<Encode::PerlIO>.
+except for hz and ISO-2022-kr. For gory details, see L<Encode::Encoding> and L<Encode::PerlIO>.
=head1 Handling Malformed Data
If I<CHECK> is 0, (en|de)code will put a I<substitution character>
in place of a malformed character. For UCM-based encodings,
-E<lt>subcharE<gt> will be used. For Unicode, "\x{FFFD}" is used.
+E<lt>subcharE<gt> will be used. For Unicode, the code point C<0xFFFD> is used.
If the data is supposed to be UTF-8, an optional lexical warning
(category utf8) is given.
=item I<CHECK> = Encode::FB_CROAK ( == 1)
-If I<CHECK> is 1, methods will die immediately with an error
+If I<CHECK> is 1, methods will die on error immediately with an error
message. Therefore, when I<CHECK> is set to 1, you should trap the
fatal error with eval{} unless you really want to let it die on error.
sequences, for example because you are reading with a fixed-width
buffer. Here is some sample code that does exactly this:
- my $data = '';
+ my $data = ''; my $utf8 = '';
while(defined(read $fh, $buffer, 256)){
# buffer may end in a partial character so we append
$data .= $buffer;
- $utf8 .= decode($encoding, $data, ENCODE::FB_QUIET);
+ $utf8 .= decode($encoding, $data, Encode::FB_QUIET);
# $data now contains the unprocessed partial character
}
For encodings that are implemented by Encode::XS, CHECK ==
Encode::FB_PERLQQ turns (en|de)code into C<perlqq> fallback mode.
-When you decode, '\xI<XX>' will be inserted for a malformed character,
-where I<XX> is the hex representation of the octet that could not be
-decoded to utf8. And when you encode, '\x{I<xxxx>}' will be inserted,
-where I<xxxx> is the Unicode ID of the character that cannot be found
+When you decode, C<\xI<HH>> will be inserted for a malformed character,
+where I<HH> is the hex representation of the octet that could not be
+decoded to utf8. And when you encode, C<\x{I<HHHH>}> will be inserted,
+where I<HHHH> is the Unicode ID of the character that cannot be found
in the character repertoire of the encoding.
HTML/XML character reference modes are about the same, in place of
-\x{I<xxxx>}, HTML uses &#I<1234>; where I<1234> is a decimal digit and
-XML uses &#xI<abcd>; where I<abcd> is the hexadecimal digit.
+C<\x{I<HHHH>}>, HTML uses C<&#I<NNNN>>; where I<NNNN> is a decimal digit and
+XML uses C<&#xI<HHHH>>; where I<HHHH> is the hexadecimal digit.
=item The bitmask
FB_DEFAULT FB_CROAK FB_QUIET FB_WARN FB_PERLQQ
DIE_ON_ERR 0x0001 X
- WARN_ON_ER 0x0002 X
+ WARN_ON_ERR 0x0002 X
RETURN_ON_ERR 0x0004 X X
LEAVE_SRC 0x0008
PERLQQ 0x0100 X
- HTMLCREF 0x0200
- XMLCREF 0x0400
+ HTMLCREF 0x0200
+ XMLCREF 0x0400
=head2 Unimplemented fallback schemes
In the future, you will be able to use a code reference to a callback
function for the value of I<CHECK> but its API is still undecided.
+The fallback scheme does not work on EBCDIC platforms.
+
=head1 Defining Encodings
To define a new encoding, use:
- use Encode qw(define_alias);
+ use Encode qw(define_encoding);
define_encoding($object, 'canonicalName' [, alias...]);
I<canonicalName> will be associated with I<$object>. The object
should provide the interface described in L<Encode::Encoding>.
If more than two arguments are provided then additional
-arguments are taken as aliases for I<$object>, as for C<define_alias>.
+arguments are taken as aliases for I<$object>.
See L<Encode::Encoding> for more details.
=head1 The UTF-8 flag
Before the introduction of utf8 support in perl, The C<eq> operator
-just compares internal data of the scalars. Now C<eq> means internal
-data equality AND I<the utf8 flag>. To explain why we made it so, I
-will quote page 402 of C<Programming Perl, 3rd ed.>
+just compared the strings represented by two scalars. Beginning with
+perl 5.8, C<eq> compares two strings with simultaneous consideration
+of I<the utf8 flag>. To explain why we made it so, I will quote page
+402 of C<Programming Perl, 3rd ed.>
=over 2
Back when C<Programming Perl, 3rd ed.> was written, not even Perl 5.6.0
was born and many features documented in the book remained
-unimplemented. Perl 5.8 hopefully correct this and the introduction
-of UTF-8 flag is one of them. You can think this perl notion of
-byte-oriented mode (utf8 flag off) and character-oriented mode (utf8
+unimplemented for a long time. Perl 5.8 corrected this and the introduction
+of the UTF-8 flag is one of them. You can think of this perl notion as of a
+byte-oriented mode (utf8 flag off) and a character-oriented mode (utf8
flag on).
Here is how Encode takes care of the utf8 flag.
=item
-When you decode, the resuting utf8 flag is on unless you can
+When you decode, the resulting utf8 flag is on unless you can
unambiguously represent data. Here is the definition of
dis-ambiguity.
- After C<$utf8 = decode('foo', $octet);>,
+After C<$utf8 = decode('foo', $octet);>,
When $octet is... The utf8 flag in $utf8 is
---------------------------------------------
This project was originated by Nick Ing-Simmons and later maintained
by Dan Kogai E<lt>dankogai@dan.co.jpE<gt>. See AUTHORS for a full
list of people involved. For any questions, use
-E<lt>perl-unicode@perl.orgE<gt> so we can all share share.
+E<lt>perl-unicode@perl.orgE<gt> so we can all share.
=cut
projects / p5sagit/p5-mst-13.2.git / blobdiff