[p5sagit/p5-mst-13.2.git] / ext / Encode / encoding.pm

package encoding;
our $VERSION = do { my @r = (q$Revision: 1.30 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };

use Encode;
use strict;

BEGIN {
    if (ord("A") == 193) {
	require Carp;
	Carp::croak "encoding pragma does not support EBCDIC platforms";
    }
}

our $HAS_PERLIO = exists $INC{"PerlIO/encoding.pm"};
$HAS_PERLIO or binmode(STDIN);

sub import {
    my $class = shift;
    my $name  = shift;
    my %arg = @_;
    $name ||= $ENV{PERL_ENCODING};

    my $enc = find_encoding($name);
    unless (defined $enc) {
	require Carp;
	Carp::croak "Unknown encoding '$name'";
    }
    unless ($arg{Filter}){
	${^ENCODING} = $enc; # this is all you need, actually.
	$HAS_PERLIO or return 1;
	for my $h (qw(STDIN STDOUT)){
	    if ($arg{$h}){
		unless (defined find_encoding($arg{$h})) {
		    require Carp;
		    Carp::croak "Unknown encoding for $h, '$arg{$h}'";
		}
		eval qq{ binmode($h, ":encoding($arg{$h})") };
	    }else{
		unless (exists $arg{$h}){
		    eval qq{ binmode($h, ":encoding($name)") };
		}
	    }
	    if ($@){
		require Carp;
		Carp::croak($@);
	    }
	}
    }else{
	defined(${^ENCODING}) and undef ${^ENCODING};
	eval {
	    require Filter::Util::Call ;
	    Filter::Util::Call->import ;
	    binmode(STDIN);
	    binmode(STDOUT);
	    filter_add(sub{
			   my $status;
                           if (($status = filter_read()) > 0){
			       $_ = $enc->decode($_, 1);
			       # warn $_;
			   }
			   $status ;
		       });
	};
	# warn "Filter installed";
    }
    return 1; # I doubt if we need it, though
}

sub unimport{
    no warnings;
    undef ${^ENCODING};
    binmode(STDIN);
    binmode(STDOUT);
    if ($INC{"Filter/Util/Call.pm"}){
	eval { filter_del() };
    }
}

1;
__END__

=pod

=head1 NAME

encoding -  allows you to write your script in non-asii or non-utf8

=head1 SYNOPSIS

  use encoding "greek";  # Perl like Greek to you?
  use encoding "euc-jp"; # Jperl!

  # or you can even do this if your shell supports your native encoding

  perl -Mencoding=latin2 -e '...' # Feeling centrally European?
  perl -Mencoding=euc-ko -e '...'

  # or from the shebang line

  #!/your/path/to/perl -Mencoding="8859-6" # Arabian Nights
  #!/your/path/to/perl -Mencoding=euc-tw

  # more control

  # A simple euc-cn => utf-8 converter
  use encoding "euc-cn", STDOUT => "utf8";  while(<>){print};

  # "no encoding;" supported (but not scoped!)
  no encoding;

  # an alternate way, Filter
  use encoding "euc-jp", Filter=>1;
  use utf8;
  # now you can use kanji identifiers -- in euc-jp!

=head1 ABSTRACT

Let's start with a bit of history: Perl 5.6.0 introduced Unicode
support.  You could apply C<substr()> and regexes even to complex CJK
characters -- so long as the script was written in UTF-8.  But back
then text editors that supported UTF-8 were still rare and many users
rather chose to write scripts in legacy encodings, given up whole new
feature of Perl 5.6.

Rewind to the future: starting from perl 5.8.0 with B<encoding>
pragma, you can write your script in any encoding you like (so long
as the C<Encode> module supports it) and still enjoy Unicode support.
You can write a code in EUC-JP as follows:

  my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji
               #<-char-><-char->   # 4 octets
  s/\bCamel\b/$Rakuda/;

And with C<use encoding "euc-jp"> in effect, it is the same thing as
the code in UTF-8:

  my $Rakuda = "\x{99F1}\x{99DD}"; # who Unicode Characters
  s/\bCamel\b/$Rakuda/;

The B<encoding> pragma also modifies the filehandle disciplines of
STDIN, STDOUT, and STDERR to the specified encoding.  Therefore,

  use encoding "euc-jp";
  my $message = "Camel is the symbol of perl.\n";
  my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji
  $message =~ s/\bCamel\b/$Rakuda/;
  print $message;

Will print "\xF1\xD1\xF1\xCC is the symbol of perl.\n",
not "\x{99F1}\x{99DD} is the symbol of perl.\n".

You can override this by giving extra arguments, see below.

=head1 USAGE

=over 4

=item use encoding [I<ENCNAME>] ;

Sets the script encoding to I<ENCNAME> and filehandle disciplines of
STDIN, STDOUT are set to ":encoding(I<ENCNAME>)".  Note STDERR will
not be changed.

If no encoding is specified, the environment variable L<PERL_ENCODING>
is consulted.  If no encoding can be found, the error C<Unknown encoding
'I<ENCNAME>'> will be thrown.

Note that non-STD file handles remain unaffected.  Use C<use open> or
C<binmode> to change disciplines of those.

=item use encoding I<ENCNAME> [ STDIN =E<gt> I<ENCNAME_IN> ...] ;

You can also individually set encodings of STDIN and STDOUT via
STDI<FH> =E<gt> I<ENCNAME_FH> form.  In this case, you cannot omit the
first I<ENCNAME>.  C<STDI<FH> =E<gt> undef> turns the IO transcoding
completely off.

=item no encoding;

Unsets the script encoding and the disciplines of STDIN, STDOUT are
reset to ":raw" (the default unprocessed raw stream of bytes).

=back

=head1 CAVEATS

=head2 NOT SCOPED

The pragma is a per script, not a per block lexical.  Only the last
C<use encoding> or C<matters, and it affects B<the whole script>.
However, <no encoding> pragma is supported and C<use encoding> can
appear as many times as you want in a given script.  The multiple use
of this pragma is discouraged.

=head2 DO NOT MIX MULTIPLE ENCODINGS

Notice that only literals (string or regular expression) having only
legacy code points are affected: if you mix data like this

	\xDF\x{100}

the data is assumed to be in (Latin 1 and) Unicode, not in your native
encoding.  In other words, this will match in "greek":

	"\xDF" =~ /\x{3af}/

but this will not

	"\xDF\x{100}" =~ /\x{3af}\x{100}/

since the C<\xDF> (ISO 8859-7 GREEK SMALL LETTER IOTA WITH TONOS) on
the left will B<not> be upgraded to C<\x{3af}> (Unicode GREEK SMALL
LETTER IOTA WITH TONOS) because of the C<\x{100}> on the left.  You
should not be mixing your legacy data and Unicode in the same string.

This pragma also affects encoding of the 0x80..0xFF code point range:
normally characters in that range are left as eight-bit bytes (unless
they are combined with characters with code points 0x100 or larger,
in which case all characters need to become UTF-8 encoded), but if
the C<encoding> pragma is present, even the 0x80..0xFF range always
gets UTF-8 encoded.

After all, the best thing about this pragma is that you don't have to
resort to \x... just to spell your name in native a encoding.  So feel
free to put your strings in your encoding in quotes and regexes.

=head1 Non-ASCII Identifiers and Filter option

The magic of C<use encoding> is not applied to the names of
identifiers.  In order to make C<${"4eba"}++> ($human++, where human
is a single Han ideograph) work, you still need to write your script
in UTF-8 or use a source filter.

In other words, the same restriction as Jperl applies.

If you dare to experiment, however, you can try Filter option.

=over 4

=item use encoding I<ENCNAME> Filter=E<gt>1;

This turns encoding pragma into source filter.  While the default
approach just decodes interpolated literals (in qq() and qr()), this
will apply source filter to entire source code.  In this case, STDIN
and STDOUT remain untouched.

=back

What does this mean?  Your source code behaves as if it is written in
UTF-8.  So even if your editor only supports Shift_JIS, for example.
You can still try examples in Chapter 15 of C<Programming Perl, 3rd
Ed.> For instance, you can use UTF-8 identifiers.

This option is significantly slower and (as of this writing) non-ASCII
identifiers are not very stable WITHOUT this option and with the
source code written in UTF-8.

To make your script in legacy encoding work with minimum effort,
do not use Filter=E<gt>1.

=head1 EXAMPLE - Greekperl

    use encoding "iso 8859-7";

    # The \xDF of ISO 8859-7 (Greek) is \x{3af} in Unicode.

    $a = "\xDF";
    $b = "\x{100}";

    printf "%#x\n", ord($a); # will print 0x3af, not 0xdf

    $c = $a . $b;

    # $c will be "\x{3af}\x{100}", not "\x{df}\x{100}".

    # chr() is affected, and ...

    print "mega\n"  if ord(chr(0xdf)) == 0x3af;

    # ... ord() is affected by the encoding pragma ...

    print "tera\n" if ord(pack("C", 0xdf)) == 0x3af;

    # ... as are eq and cmp ...

    print "peta\n" if "\x{3af}" eq  pack("C", 0xdf);
    print "exa\n"  if "\x{3af}" cmp pack("C", 0xdf) == 0;

    # ... but pack/unpack C are not affected, in case you still
    # want back to your native encoding

    print "zetta\n" if unpack("C", (pack("C", 0xdf))) == 0xdf;

=head1 KNOWN PROBLEMS

For native multibyte encodings (either fixed or variable length)
the current implementation of the regular expressions may introduce
recoding errors for longer regular expression literals than 127 bytes.

The encoding pragma is not supported on EBCDIC platforms.
(Porters wanted.)

=head1 SEE ALSO

L<perlunicode>, L<Encode>, L<open>, L<Filter::Util::Call>,

Ch. 15 of C<Programming Perl (3rd Edition)>
by Larry Wall, Tom Christiansen, Jon Orwant;
O'Reilly & Associates; ISBN 0-596-00027-8

=cut
Commit	Line	Data
3ef515df	1	package encoding;
85982a32	2	our $VERSION = do { my @r = (q$Revision: 1.30 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
3ef515df	3
3ef515df	4	use Encode;
046f36bf	5	use strict;
3ef515df	6
	7	BEGIN {
	8	if (ord("A") == 193) {
	9	require Carp;
	10	Carp::croak "encoding pragma does not support EBCDIC platforms";
	11	}
	12	}
	13
85982a32	14	our $HAS_PERLIO = exists $INC{"PerlIO/encoding.pm"};
85982a32	15	$HAS_PERLIO or binmode(STDIN);
b2704119	16
3ef515df	17	sub import {
	18	my $class = shift;
	19	my $name = shift;
	20	my %arg = @_;
	21	$name \|\|= $ENV{PERL_ENCODING};
	22
	23	my $enc = find_encoding($name);
	24	unless (defined $enc) {
	25	require Carp;
	26	Carp::croak "Unknown encoding '$name'";
	27	}
aae85ceb	28	unless ($arg{Filter}){
aae85ceb	29	${^ENCODING} = $enc; # this is all you need, actually.
85982a32	30	$HAS_PERLIO or return 1;
aae85ceb	31	for my $h (qw(STDIN STDOUT)){
aae85ceb	32	if ($arg{$h}){
b2704119	33	unless (defined find_encoding($arg{$h})) {
aae85ceb	34	require Carp;
	35	Carp::croak "Unknown encoding for $h, '$arg{$h}'";
	36	}
	37	eval qq{ binmode($h, ":encoding($arg{$h})") };
	38	}else{
	39	unless (exists $arg{$h}){
	40	eval qq{ binmode($h, ":encoding($name)") };
	41	}
	42	}
	43	if ($@){
3ef515df	44	require Carp;
aae85ceb	45	Carp::croak($@);
3ef515df	46	}
3ef515df	47	}
aae85ceb	48	}else{
	49	defined(${^ENCODING}) and undef ${^ENCODING};
	50	eval {
	51	require Filter::Util::Call ;
	52	Filter::Util::Call->import ;
b2704119	53	binmode(STDIN);
b2704119	54	binmode(STDOUT);
aae85ceb	55	filter_add(sub{
	56	my $status;
	57	if (($status = filter_read()) > 0){
	58	$_ = $enc->decode($_, 1);
	59	# warn $_;
	60	}
	61	$status ;
	62	});
	63	};
	64	# warn "Filter installed";
3ef515df	65	}
	66	return 1; # I doubt if we need it, though
	67	}
	68
	69	sub unimport{
	70	no warnings;
	71	undef ${^ENCODING};
b2704119	72	binmode(STDIN);
b2704119	73	binmode(STDOUT);
aae85ceb	74	if ($INC{"Filter/Util/Call.pm"}){
	75	eval { filter_del() };
	76	}
3ef515df	77	}
	78
	79	1;
	80	__END__
85982a32	81
3ef515df	82	=pod
	83
	84	=head1 NAME
	85
	86	encoding - allows you to write your script in non-asii or non-utf8
	87
	88	=head1 SYNOPSIS
	89
962111ca	90	use encoding "greek"; # Perl like Greek to you?
3ef515df	91	use encoding "euc-jp"; # Jperl!
3ef515df	92
962111ca	93	# or you can even do this if your shell supports your native encoding
3ef515df	94
962111ca	95	perl -Mencoding=latin2 -e '...' # Feeling centrally European?
962111ca	96	perl -Mencoding=euc-ko -e '...'
3ef515df	97
	98	# or from the shebang line
	99
962111ca	100	#!/your/path/to/perl -Mencoding="8859-6" # Arabian Nights
962111ca	101	#!/your/path/to/perl -Mencoding=euc-tw
3ef515df	102
	103	# more control
	104
962111ca	105	# A simple euc-cn => utf-8 converter
962111ca	106	use encoding "euc-cn", STDOUT => "utf8"; while(<>){print};
3ef515df	107
	108	# "no encoding;" supported (but not scoped!)
	109	no encoding;
	110
aae85ceb	111	# an alternate way, Filter
	112	use encoding "euc-jp", Filter=>1;
	113	use utf8;
	114	# now you can use kanji identifiers -- in euc-jp!
	115
3ef515df	116	=head1 ABSTRACT
3ef515df	117
962111ca	118	Let's start with a bit of history: Perl 5.6.0 introduced Unicode
	119	support. You could apply C<substr()> and regexes even to complex CJK
	120	characters -- so long as the script was written in UTF-8. But back
	121	then text editors that supported UTF-8 were still rare and many users
	122	rather chose to write scripts in legacy encodings, given up whole new
	123	feature of Perl 5.6.
3ef515df	124
962111ca	125	Rewind to the future: starting from perl 5.8.0 with B<encoding>
	126	pragma, you can write your script in any encoding you like (so long
	127	as the C<Encode> module supports it) and still enjoy Unicode support.
	128	You can write a code in EUC-JP as follows:
3ef515df	129
	130	my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji
	131	#<-char-><-char-> # 4 octets
	132	s/\bCamel\b/$Rakuda/;
	133
	134	And with C<use encoding "euc-jp"> in effect, it is the same thing as
962111ca	135	the code in UTF-8:
3ef515df	136
	137	my $Rakuda = "\x{99F1}\x{99DD}"; # who Unicode Characters
	138	s/\bCamel\b/$Rakuda/;
	139
962111ca	140	The B<encoding> pragma also modifies the filehandle disciplines of
3ef515df	141	STDIN, STDOUT, and STDERR to the specified encoding. Therefore,
	142
	143	use encoding "euc-jp";
	144	my $message = "Camel is the symbol of perl.\n";
	145	my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji
	146	$message =~ s/\bCamel\b/$Rakuda/;
	147	print $message;
	148
962111ca	149	Will print "\xF1\xD1\xF1\xCC is the symbol of perl.\n",
962111ca	150	not "\x{99F1}\x{99DD} is the symbol of perl.\n".
3ef515df	151
962111ca	152	You can override this by giving extra arguments, see below.
3ef515df	153
	154	=head1 USAGE
	155
	156	=over 4
	157
	158	=item use encoding [I<ENCNAME>] ;
	159
962111ca	160	Sets the script encoding to I<ENCNAME> and filehandle disciplines of
	161	STDIN, STDOUT are set to ":encoding(I<ENCNAME>)". Note STDERR will
	162	not be changed.
3ef515df	163
3ef515df	164	If no encoding is specified, the environment variable L<PERL_ENCODING>
962111ca	165	is consulted. If no encoding can be found, the error C<Unknown encoding
962111ca	166	'I<ENCNAME>'> will be thrown.
3ef515df	167
	168	Note that non-STD file handles remain unaffected. Use C<use open> or
	169	C<binmode> to change disciplines of those.
	170
aae85ceb	171	=item use encoding I<ENCNAME> [ STDIN =E<gt> I<ENCNAME_IN> ...] ;
3ef515df	172
aae85ceb	173	You can also individually set encodings of STDIN and STDOUT via
aae85ceb	174	STDI<FH> =E<gt> I<ENCNAME_FH> form. In this case, you cannot omit the
962111ca	175	first I<ENCNAME>. C<STDI<FH> =E<gt> undef> turns the IO transcoding
aae85ceb	176	completely off.
3ef515df	177
	178	=item no encoding;
	179
f2a2953c	180	Unsets the script encoding and the disciplines of STDIN, STDOUT are
962111ca	181	reset to ":raw" (the default unprocessed raw stream of bytes).
3ef515df	182
	183	=back
	184
	185	=head1 CAVEATS
	186
	187	=head2 NOT SCOPED
	188
	189	The pragma is a per script, not a per block lexical. Only the last
	190	C<use encoding> or C<matters, and it affects B<the whole script>.
962111ca	191	However, <no encoding> pragma is supported and C<use encoding> can
962111ca	192	appear as many times as you want in a given script. The multiple use
3ef515df	193	of this pragma is discouraged.
	194
	195	=head2 DO NOT MIX MULTIPLE ENCODINGS
	196
	197	Notice that only literals (string or regular expression) having only
	198	legacy code points are affected: if you mix data like this
	199
	200	\xDF\x{100}
	201
	202	the data is assumed to be in (Latin 1 and) Unicode, not in your native
	203	encoding. In other words, this will match in "greek":
	204
	205	"\xDF" =~ /\x{3af}/
	206
	207	but this will not
	208
	209	"\xDF\x{100}" =~ /\x{3af}\x{100}/
	210
962111ca	211	since the C<\xDF> (ISO 8859-7 GREEK SMALL LETTER IOTA WITH TONOS) on
	212	the left will B<not> be upgraded to C<\x{3af}> (Unicode GREEK SMALL
	213	LETTER IOTA WITH TONOS) because of the C<\x{100}> on the left. You
	214	should not be mixing your legacy data and Unicode in the same string.
3ef515df	215
	216	This pragma also affects encoding of the 0x80..0xFF code point range:
	217	normally characters in that range are left as eight-bit bytes (unless
	218	they are combined with characters with code points 0x100 or larger,
	219	in which case all characters need to become UTF-8 encoded), but if
	220	the C<encoding> pragma is present, even the 0x80..0xFF range always
	221	gets UTF-8 encoded.
	222
	223	After all, the best thing about this pragma is that you don't have to
962111ca	224	resort to \x... just to spell your name in native a encoding. So feel
3ef515df	225	free to put your strings in your encoding in quotes and regexes.
3ef515df	226
962111ca	227	=head1 Non-ASCII Identifiers and Filter option
aae85ceb	228
962111ca	229	The magic of C<use encoding> is not applied to the names of
	230	identifiers. In order to make C<${"4eba"}++> ($human++, where human
	231	is a single Han ideograph) work, you still need to write your script
	232	in UTF-8 or use a source filter.
aae85ceb	233
	234	In other words, the same restriction as Jperl applies.
	235
962111ca	236	If you dare to experiment, however, you can try Filter option.
aae85ceb	237
	238	=over 4
	239
	240	=item use encoding I<ENCNAME> Filter=E<gt>1;
	241
	242	This turns encoding pragma into source filter. While the default
	243	approach just decodes interpolated literals (in qq() and qr()), this
	244	will apply source filter to entire source code. In this case, STDIN
	245	and STDOUT remain untouched.
	246
	247	=back
	248
962111ca	249	What does this mean? Your source code behaves as if it is written in
	250	UTF-8. So even if your editor only supports Shift_JIS, for example.
	251	You can still try examples in Chapter 15 of C<Programming Perl, 3rd
	252	Ed.> For instance, you can use UTF-8 identifiers.
aae85ceb	253
	254	This option is significantly slower and (as of this writing) non-ASCII
	255	identifiers are not very stable WITHOUT this option and with the
	256	source code written in UTF-8.
	257
962111ca	258	To make your script in legacy encoding work with minimum effort,
962111ca	259	do not use Filter=E<gt>1.
aae85ceb	260
3ef515df	261	=head1 EXAMPLE - Greekperl
	262
	263	use encoding "iso 8859-7";
	264
	265	# The \xDF of ISO 8859-7 (Greek) is \x{3af} in Unicode.
	266
	267	$a = "\xDF";
	268	$b = "\x{100}";
	269
	270	printf "%#x\n", ord($a); # will print 0x3af, not 0xdf
	271
	272	$c = $a . $b;
	273
	274	# $c will be "\x{3af}\x{100}", not "\x{df}\x{100}".
	275
	276	# chr() is affected, and ...
	277
	278	print "mega\n" if ord(chr(0xdf)) == 0x3af;
	279
	280	# ... ord() is affected by the encoding pragma ...
	281
	282	print "tera\n" if ord(pack("C", 0xdf)) == 0x3af;
	283
	284	# ... as are eq and cmp ...
	285
	286	print "peta\n" if "\x{3af}" eq pack("C", 0xdf);
	287	print "exa\n" if "\x{3af}" cmp pack("C", 0xdf) == 0;
	288
	289	# ... but pack/unpack C are not affected, in case you still
	290	# want back to your native encoding
	291
	292	print "zetta\n" if unpack("C", (pack("C", 0xdf))) == 0xdf;
	293
	294	=head1 KNOWN PROBLEMS
	295
	296	For native multibyte encodings (either fixed or variable length)
	297	the current implementation of the regular expressions may introduce
	298	recoding errors for longer regular expression literals than 127 bytes.
	299
	300	The encoding pragma is not supported on EBCDIC platforms.
	301	(Porters wanted.)
	302
	303	=head1 SEE ALSO
	304
aae85ceb	305	L<perlunicode>, L<Encode>, L<open>, L<Filter::Util::Call>,
	306
	307	Ch. 15 of C<Programming Perl (3rd Edition)>
	308	by Larry Wall, Tom Christiansen, Jon Orwant;
	309	O'Reilly & Associates; ISBN 0-596-00027-8
3ef515df	310
3ef515df	311	=cut