[p5sagit/p5-mst-13.2.git] / lib / open.pm

package open;
use warnings;
use Carp;
$open::hint_bits = 0x20000; # HINT_LOCALIZE_HH

our $VERSION = '1.03';

my $locale_encoding;

sub in_locale { $^H & ($locale::hint_bits || 0)}

sub _get_locale_encoding {
    unless (defined $locale_encoding) {
	# I18N::Langinfo isn't available everywhere
	eval {
	    require I18N::Langinfo;
	    I18N::Langinfo->import(qw(langinfo CODESET));
	    $locale_encoding = langinfo(CODESET());
	};
	my $country_language;

	no warnings 'uninitialized';

        if (not $locale_encoding && in_locale()) {
	    if ($ENV{LC_ALL} =~ /^([^.]+)\.([^.]+)$/) {
		($country_language, $locale_encoding) = ($1, $2);
	    } elsif ($ENV{LANG} =~ /^([^.]+)\.([^.]+)$/) {
		($country_language, $locale_encoding) = ($1, $2);
	    }
	    # LANGUAGE affects only LC_MESSAGES only on glibc
	} elsif (not $locale_encoding) {
	    if ($ENV{LC_ALL} =~ /\butf-?8\b/i ||
		$ENV{LANG}   =~ /\butf-?8\b/i) {
		$locale_encoding = 'utf8';
	    }
	    # Could do more heuristics based on the country and language
	    # parts of LC_ALL and LANG (the parts before the dot (if any)),
	    # since we have Locale::Country and Locale::Language available.
	    # TODO: get a database of Language -> Encoding mappings
	    # (the Estonian database at http://www.eki.ee/letter/
	    # would be excellent!) --jhi
	}
	if (defined $locale_encoding &&
	    lc($locale_encoding) eq 'euc' &&
	    defined $country_language) {
	    if ($country_language =~ /^ja_JP|japan(?:ese)?$/i) {
		$locale_encoding = 'euc-jp';
	    } elsif ($country_language =~ /^ko_KR|korean?$/i) {
		$locale_encoding = 'euc-kr';
	    } elsif ($country_language =~ /^zh_CN|chin(?:a|ese)?$/i) {
		$locale_encoding = 'euc-cn';
	    } elsif ($country_language =~ /^zh_TW|taiwan(?:ese)?$/i) {
		$locale_encoding = 'euc-tw';
	    } else {
		croak "Locale encoding 'euc' too ambiguous";
	    }
	}
    }
}

sub import {
    my ($class,@args) = @_;
    croak("`use open' needs explicit list of PerlIO layers") unless @args;
    my $std;
    $^H |= $open::hint_bits;
    my ($in,$out) = split(/\0/,(${^OPEN} || "\0"), -1);
    while (@args) {
	my $type = shift(@args);
	my $dscp;
	if ($type =~ /^:?(utf8|locale|encoding\(.+\))$/) {
	    $type = 'IO';
	    $dscp = ":$1";
	} elsif ($type eq ':std') {
	    $std = 1;
	    next;
	} else {
	    $dscp = shift(@args) || '';
	}
	my @val;
	foreach my $layer (split(/\s+/,$dscp)) {
            $layer =~ s/^://;
	    if ($layer eq 'locale') {
		require Encode;
		_get_locale_encoding()
		    unless defined $locale_encoding;
		(warnings::warnif("layer", "Cannot figure out an encoding to use"), last)
		    unless defined $locale_encoding;
		if ($locale_encoding =~ /^utf-?8$/i) {
		    $layer = "utf8";
		} else {
		    $layer = "encoding($locale_encoding)";
		}
		$std = 1;
	    } else {
		my $target = $layer;		# the layer name itself
		$target =~ s/^(\w+)\(.+\)$/$1/;	# strip parameters

		unless(PerlIO::Layer::->find($target,1)) {
		    warnings::warnif("layer", "Unknown PerlIO layer '$target'");
		}
	    }
	    push(@val,":$layer");
	    if ($layer =~ /^(crlf|raw)$/) {
		$^H{"open_$type"} = $layer;
	    }
	}
	if ($type eq 'IN') {
	    $in  = join(' ',@val);
	}
	elsif ($type eq 'OUT') {
	    $out = join(' ',@val);
	}
	elsif ($type eq 'IO') {
	    $in = $out = join(' ',@val);
	}
	else {
	    croak "Unknown PerlIO layer class '$type'";
	}
    }
    ${^OPEN} = join("\0",$in,$out) if $in or $out;
    if ($std) {
	if ($in) {
	    if ($in =~ /:utf8\b/) {
		    binmode(STDIN,  ":utf8");
		} elsif ($in =~ /(\w+\(.+\))/) {
		    binmode(STDIN,  ":$1");
		}
	}
	if ($out) {
	    if ($out =~ /:utf8\b/) {
		binmode(STDOUT,  ":utf8");
		binmode(STDERR,  ":utf8");
	    } elsif ($out =~ /(\w+\(.+\))/) {
		binmode(STDOUT,  ":$1");
		binmode(STDERR,  ":$1");
	    }
	}
    }
}

1;
__END__

=head1 NAME

open - perl pragma to set default PerlIO layers for input and output

=head1 SYNOPSIS

    use open IN  => ":crlf", OUT => ":bytes";
    use open OUT => ':utf8';
    use open IO  => ":encoding(iso-8859-7)";

    use open IO  => ':locale';

    use open ':utf8';
    use open ':locale';
    use open ':encoding(iso-8859-7)';

    use open ':std';

=head1 DESCRIPTION

Full-fledged support for I/O layers is now implemented provided
Perl is configured to use PerlIO as its IO system (which is now the
default).

The C<open> pragma serves as one of the interfaces to declare default
"layers" (also known as "disciplines") for all I/O. Any two-argument
open(), readpipe() (aka qx//) and similar operators found within the
lexical scope of this pragma will use the declared defaults.
Three-argument opens are not affected by this pragma since there you
(can) explicitly specify the layers and are supposed to know what you
are doing.

With the C<IN> subpragma you can declare the default layers
of input streams, and with the C<OUT> subpragma you can declare
the default layers of output streams.  With the C<IO>  subpragma
you can control both input and output streams simultaneously.

If you have a legacy encoding, you can use the C<:encoding(...)> tag.

if you want to set your encoding layers based on your
locale environment variables, you can use the C<:locale> tag.
For example:

    $ENV{LANG} = 'ru_RU.KOI8-R';
    # the :locale will probe the locale environment variables like LANG
    use open OUT => ':locale';
    open(O, ">koi8");
    print O chr(0x430); # Unicode CYRILLIC SMALL LETTER A = KOI8-R 0xc1
    close O;
    open(I, "<koi8");
    printf "%#x\n", ord(<I>), "\n"; # this should print 0xc1
    close I;

These are equivalent

    use open ':utf8';
    use open IO => ':utf8';

as are these

    use open ':locale';
    use open IO => ':locale';

and these

    use open ':encoding(iso-8859-7)';
    use open IO => ':encoding(iso-8859-7)';

The matching of encoding names is loose: case does not matter, and
many encodings have several aliases.  See L<Encode::Supported> for
details and the list of supported locales.

Note that C<:utf8> PerlIO layer must always be specified exactly like
that, it is not subject to the loose matching of encoding names.

When open() is given an explicit list of layers they are appended to
the list declared using this pragma.

The C<:std> subpragma on its own has no effect, but if combined with
the C<:utf8> or C<:encoding> subpragmas, it converts the standard
filehandles (STDIN, STDOUT, STDERR) to comply with encoding selected
for input/output handles.  For example, if both input and out are
chosen to be C<:utf8>, a C<:std> will mean that STDIN, STDOUT, and
STDERR are also in C<:utf8>.  On the other hand, if only output is
chosen to be in C<< :encoding(koi8r) >>, a C<:std> will cause only the
STDOUT and STDERR to be in C<koi8r>.  The C<:locale> subpragma
implicitly turns on C<:std>.

The logic of C<:locale> is as follows:

=over 4

=item 1.

If the platform supports the langinfo(CODESET) interface, the codeset
returned is used as the default encoding for the open pragma.

=item 2.

If 1. didn't work but we are under the locale pragma, the environment
variables LC_ALL and LANG (in that order) are matched for encodings
(the part after C<.>, if any), and if any found, that is used 
as the default encoding for the open pragma.

=item 3.

If 1. and 2. didn't work, the environment variables LC_ALL and LANG
(in that order) are matched for anything looking like UTF-8, and if
any found, C<:utf8> is used as the default encoding for the open
pragma.

=back

If your locale environment variables (LC_ALL, LC_CTYPE, LANG)
contain the strings 'UTF-8' or 'UTF8' (case-insensitive matching),
the default encoding of your STDIN, STDOUT, and STDERR, and of
B<any subsequent file open>, is UTF-8.

Directory handles may also support PerlIO layers in the future.

=head1 NONPERLIO FUNCTIONALITY

If Perl is not built to use PerlIO as its IO system then only the two
pseudo-layers C<:bytes> and C<:crlf> are available.

The C<:bytes> layer corresponds to "binary mode" and the C<:crlf>
layer corresponds to "text mode" on platforms that distinguish
between the two modes when opening files (which is many DOS-like
platforms, including Windows).  These two layers are no-ops on
platforms where binmode() is a no-op, but perform their functions
everywhere if PerlIO is enabled.

=head1 IMPLEMENTATION DETAILS

There is a class method in C<PerlIO::Layer> C<find> which is
implemented as XS code.  It is called by C<import> to validate the
layers:

   PerlIO::Layer::->find("perlio")

The return value (if defined) is a Perl object, of class
C<PerlIO::Layer> which is created by the C code in F<perlio.c>.  As
yet there is nothing useful you can do with the object at the perl
level.

=head1 SEE ALSO

L<perlfunc/"binmode">, L<perlfunc/"open">, L<perlunicode>, L<PerlIO>,
L<encoding>

=cut
Commit	Line	Data
d1edabcf	1	package open;
99ef548b	2	use warnings;
ac27b0f5	3	use Carp;
9cfe5470	4	$open::hint_bits = 0x20000; # HINT_LOCALIZE_HH
16fe6d59	5
8f6960ea	6	our $VERSION = '1.03';
b75c8c73	7
58d53262	8	my $locale_encoding;
58d53262	9
b178108d	10	sub in_locale { $^H & ($locale::hint_bits \|\| 0)}
58d53262	11
	12	sub _get_locale_encoding {
	13	unless (defined $locale_encoding) {
276c9210	14	# I18N::Langinfo isn't available everywhere
9615f2ee	15	eval {
	16	require I18N::Langinfo;
	17	I18N::Langinfo->import(qw(langinfo CODESET));
ba6ce41c	18	$locale_encoding = langinfo(CODESET());
9615f2ee	19	};
11fc5dc3	20	my $country_language;
a4157ebb	21
	22	no warnings 'uninitialized';
	23
58d53262	24	if (not $locale_encoding && in_locale()) {
11fc5dc3	25	if ($ENV{LC_ALL} =~ /^([^.]+)\.([^.]+)$/) {
	26	($country_language, $locale_encoding) = ($1, $2);
	27	} elsif ($ENV{LANG} =~ /^([^.]+)\.([^.]+)$/) {
	28	($country_language, $locale_encoding) = ($1, $2);
58d53262	29	}
61de9fb5	30	# LANGUAGE affects only LC_MESSAGES only on glibc
1e616cf5	31	} elsif (not $locale_encoding) {
	32	if ($ENV{LC_ALL} =~ /\butf-?8\b/i \|\|
	33	$ENV{LANG} =~ /\butf-?8\b/i) {
	34	$locale_encoding = 'utf8';
	35	}
	36	# Could do more heuristics based on the country and language
58d53262	37	# parts of LC_ALL and LANG (the parts before the dot (if any)),
	38	# since we have Locale::Country and Locale::Language available.
	39	# TODO: get a database of Language -> Encoding mappings
421e5dc3	40	# (the Estonian database at http://www.eki.ee/letter/
421e5dc3	41	# would be excellent!) --jhi
58d53262	42	}
11fc5dc3	43	if (defined $locale_encoding &&
8f6960ea	44	lc($locale_encoding) eq 'euc' &&
11fc5dc3	45	defined $country_language) {
56fb2e42	46	if ($country_language =~ /^ja_JP\|japan(?:ese)?$/i) {
1e616cf5	47	$locale_encoding = 'euc-jp';
5a192dee	48	} elsif ($country_language =~ /^ko_KR\|korean?$/i) {
1e616cf5	49	$locale_encoding = 'euc-kr';
a4157ebb	50	} elsif ($country_language =~ /^zh_CN\|chin(?:a\|ese)?$/i) {
a4157ebb	51	$locale_encoding = 'euc-cn';
56fb2e42	52	} elsif ($country_language =~ /^zh_TW\|taiwan(?:ese)?$/i) {
011f8d22	53	$locale_encoding = 'euc-tw';
8f6960ea	54	} else {
8f6960ea	55	croak "Locale encoding 'euc' too ambiguous";
11fc5dc3	56	}
11fc5dc3	57	}
58d53262	58	}
	59	}
	60
16fe6d59	61	sub import {
dfebf958	62	my ($class,@args) = @_;
e2d9456f	63	croak("`use open' needs explicit list of PerlIO layers") unless @args;
b178108d	64	my $std;
16fe6d59	65	$^H \|= $open::hint_bits;
ba6ce41c	66	my ($in,$out) = split(/\0/,(${^OPEN} \|\| "\0"), -1);
dfebf958	67	while (@args) {
dfebf958	68	my $type = shift(@args);
1e616cf5	69	my $dscp;
	70	if ($type =~ /^:?(utf8\|locale\|encoding\(.+\))$/) {
	71	$type = 'IO';
	72	$dscp = ":$1";
b178108d	73	} elsif ($type eq ':std') {
	74	$std = 1;
	75	next;
1e616cf5	76	} else {
725d232a	77	$dscp = shift(@args) \|\| '';
1e616cf5	78	}
ac27b0f5	79	my @val;
1e616cf5	80	foreach my $layer (split(/\s+/,$dscp)) {
dfebf958	81	$layer =~ s/^://;
58d53262	82	if ($layer eq 'locale') {
54cfe943	83	require Encode;
58d53262	84	_get_locale_encoding()
58d53262	85	unless defined $locale_encoding;
99ef548b	86	(warnings::warnif("layer", "Cannot figure out an encoding to use"), last)
58d53262	87	unless defined $locale_encoding;
11fc5dc3	88	if ($locale_encoding =~ /^utf-?8$/i) {
	89	$layer = "utf8";
	90	} else {
738b23dc	91	$layer = "encoding($locale_encoding)";
11fc5dc3	92	}
b178108d	93	$std = 1;
97ed432b	94	} else {
011f8d22	95	my $target = $layer; # the layer name itself
	96	$target =~ s/^(\w+)\(.+\)$/$1/; # strip parameters
	97
c7732655	98	unless(PerlIO::Layer::->find($target,1)) {
c7732655	99	warnings::warnif("layer", "Unknown PerlIO layer '$target'");
97ed432b	100	}
ac27b0f5	101	}
	102	push(@val,":$layer");
	103	if ($layer =~ /^(crlf\|raw)$/) {
	104	$^H{"open_$type"} = $layer;
16fe6d59	105	}
ac27b0f5	106	}
	107	if ($type eq 'IN') {
	108	$in = join(' ',@val);
	109	}
	110	elsif ($type eq 'OUT') {
	111	$out = join(' ',@val);
16fe6d59	112	}
1e616cf5	113	elsif ($type eq 'IO') {
f3b00462	114	$in = $out = join(' ',@val);
f3b00462	115	}
16fe6d59	116	else {
e2d9456f	117	croak "Unknown PerlIO layer class '$type'";
16fe6d59	118	}
16fe6d59	119	}
a4157ebb	120	${^OPEN} = join("\0",$in,$out) if $in or $out;
b178108d	121	if ($std) {
	122	if ($in) {
	123	if ($in =~ /:utf8\b/) {
	124	binmode(STDIN, ":utf8");
	125	} elsif ($in =~ /(\w+\(.+\))/) {
	126	binmode(STDIN, ":$1");
	127	}
	128	}
	129	if ($out) {
	130	if ($out =~ /:utf8\b/) {
	131	binmode(STDOUT, ":utf8");
	132	binmode(STDERR, ":utf8");
	133	} elsif ($out =~ /(\w+\(.+\))/) {
	134	binmode(STDOUT, ":$1");
	135	binmode(STDERR, ":$1");
	136	}
	137	}
	138	}
16fe6d59	139	}
	140
	141	1;
	142	__END__
d1edabcf	143
	144	=head1 NAME
	145
e2d9456f	146	open - perl pragma to set default PerlIO layers for input and output
d1edabcf	147
	148	=head1 SYNOPSIS
	149
d5563ed7	150	use open IN => ":crlf", OUT => ":bytes";
1e616cf5	151	use open OUT => ':utf8';
	152	use open IO => ":encoding(iso-8859-7)";
	153
	154	use open IO => ':locale';
725d232a	155
1e616cf5	156	use open ':utf8';
	157	use open ':locale';
	158	use open ':encoding(iso-8859-7)';
d1edabcf	159
b178108d	160	use open ':std';
b178108d	161
d1edabcf	162	=head1 DESCRIPTION
d1edabcf	163
e2d9456f	164	Full-fledged support for I/O layers is now implemented provided
d151aa0e	165	Perl is configured to use PerlIO as its IO system (which is now the
d151aa0e	166	default).
16fe6d59	167
7d3b96bb	168	The C<open> pragma serves as one of the interfaces to declare default
16479489	169	"layers" (also known as "disciplines") for all I/O. Any two-argument
	170	open(), readpipe() (aka qx//) and similar operators found within the
	171	lexical scope of this pragma will use the declared defaults.
	172	Three-argument opens are not affected by this pragma since there you
	173	(can) explicitly specify the layers and are supposed to know what you
	174	are doing.
7d3b96bb	175
1e616cf5	176	With the C<IN> subpragma you can declare the default layers
d8d29d4f	177	of input streams, and with the C<OUT> subpragma you can declare
1e616cf5	178	the default layers of output streams. With the C<IO> subpragma
	179	you can control both input and output streams simultaneously.
	180
	181	If you have a legacy encoding, you can use the C<:encoding(...)> tag.
	182
e2d9456f	183	if you want to set your encoding layers based on your
1e616cf5	184	locale environment variables, you can use the C<:locale> tag.
	185	For example:
	186
	187	$ENV{LANG} = 'ru_RU.KOI8-R';
dbd62f41	188	# the :locale will probe the locale environment variables like LANG
dbd62f41	189	use open OUT => ':locale';
1e616cf5	190	open(O, ">koi8");
23bcb45a	191	print O chr(0x430); # Unicode CYRILLIC SMALL LETTER A = KOI8-R 0xc1
1e616cf5	192	close O;
1e616cf5	193	open(I, "<koi8");
23bcb45a	194	printf "%#x\n", ord(<I>), "\n"; # this should print 0xc1
1e616cf5	195	close I;
	196
	197	These are equivalent
	198
	199	use open ':utf8';
	200	use open IO => ':utf8';
	201
	202	as are these
	203
	204	use open ':locale';
	205	use open IO => ':locale';
	206
	207	and these
	208
	209	use open ':encoding(iso-8859-7)';
	210	use open IO => ':encoding(iso-8859-7)';
	211
b5d8778e	212	The matching of encoding names is loose: case does not matter, and
	213	many encodings have several aliases. See L<Encode::Supported> for
	214	details and the list of supported locales.
	215
e2d9456f	216	Note that C<:utf8> PerlIO layer must always be specified exactly like
b5d8778e	217	that, it is not subject to the loose matching of encoding names.
b5d8778e	218
d151aa0e	219	When open() is given an explicit list of layers they are appended to
d151aa0e	220	the list declared using this pragma.
7d3b96bb	221
b178108d	222	The C<:std> subpragma on its own has no effect, but if combined with
	223	the C<:utf8> or C<:encoding> subpragmas, it converts the standard
	224	filehandles (STDIN, STDOUT, STDERR) to comply with encoding selected
	225	for input/output handles. For example, if both input and out are
	226	chosen to be C<:utf8>, a C<:std> will mean that STDIN, STDOUT, and
	227	STDERR are also in C<:utf8>. On the other hand, if only output is
fb80c70c	228	chosen to be in C<< :encoding(koi8r) >>, a C<:std> will cause only the
b178108d	229	STDOUT and STDERR to be in C<koi8r>. The C<:locale> subpragma
	230	implicitly turns on C<:std>.
	231
ba9a69eb	232	The logic of C<:locale> is as follows:
	233
	234	=over 4
	235
	236	=item 1.
	237
	238	If the platform supports the langinfo(CODESET) interface, the codeset
	239	returned is used as the default encoding for the open pragma.
	240
	241	=item 2.
	242
	243	If 1. didn't work but we are under the locale pragma, the environment
	244	variables LC_ALL and LANG (in that order) are matched for encodings
	245	(the part after C<.>, if any), and if any found, that is used
	246	as the default encoding for the open pragma.
	247
	248	=item 3.
	249
	250	If 1. and 2. didn't work, the environment variables LC_ALL and LANG
	251	(in that order) are matched for anything looking like UTF-8, and if
	252	any found, C<:utf8> is used as the default encoding for the open
	253	pragma.
	254
	255	=back
	256
61de9fb5	257	If your locale environment variables (LC_ALL, LC_CTYPE, LANG)
b310b053	258	contain the strings 'UTF-8' or 'UTF8' (case-insensitive matching),
	259	the default encoding of your STDIN, STDOUT, and STDERR, and of
	260	B<any subsequent file open>, is UTF-8.
	261
e2d9456f	262	Directory handles may also support PerlIO layers in the future.
7d3b96bb	263
	264	=head1 NONPERLIO FUNCTIONALITY
	265
d151aa0e	266	If Perl is not built to use PerlIO as its IO system then only the two
e2d9456f	267	pseudo-layers C<:bytes> and C<:crlf> are available.
16fe6d59	268
e2d9456f	269	The C<:bytes> layer corresponds to "binary mode" and the C<:crlf>
e2d9456f	270	layer corresponds to "text mode" on platforms that distinguish
16fe6d59	271	between the two modes when opening files (which is many DOS-like
e2d9456f	272	platforms, including Windows). These two layers are no-ops on
d151aa0e	273	platforms where binmode() is a no-op, but perform their functions
d151aa0e	274	everywhere if PerlIO is enabled.
7d3b96bb	275
7d3b96bb	276	=head1 IMPLEMENTATION DETAILS
d1edabcf	277
f3b00462	278	There is a class method in C<PerlIO::Layer> C<find> which is
	279	implemented as XS code. It is called by C<import> to validate the
	280	layers:
0c4f7ff0	281
	282	PerlIO::Layer::->find("perlio")
	283
f3b00462	284	The return value (if defined) is a Perl object, of class
	285	C<PerlIO::Layer> which is created by the C code in F<perlio.c>. As
	286	yet there is nothing useful you can do with the object at the perl
	287	level.
16fe6d59	288
d1edabcf	289	=head1 SEE ALSO
d1edabcf	290
1768d7eb	291	L<perlfunc/"binmode">, L<perlfunc/"open">, L<perlunicode>, L<PerlIO>,
1768d7eb	292	L<encoding>
d1edabcf	293
d1edabcf	294	=cut