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package open;
use Carp;
$open::hint_bits = 0x20000;
our $VERSION = '1.01';
my $locale_encoding;
sub in_locale { $^H & $locale::hint_bits }
sub _get_locale_encoding {
unless (defined $locale_encoding) {
eval {
# I18N::Langinfo isn't available everywhere
require I18N::Langinfo;
I18N::Langinfo->import('langinfo', 'CODESET');
};
unless ($@) {
$locale_encoding = langinfo(CODESET());
}
my $country_language;
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);
}
} 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 &&
$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_TW|taiwan(?:ese)?$/i) {
$locale_encoding = 'euc-tw';
}
croak "Locale encoding 'euc' too ambiguous"
if $locale_encoding eq 'euc';
}
}
}
sub import {
my ($class,@args) = @_;
croak("`use open' needs explicit list of disciplines") unless @args;
$^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";
} else {
$dscp = shift(@args);
}
my @val;
foreach my $layer (split(/\s+/,$dscp)) {
$layer =~ s/^://;
if ($layer eq 'locale') {
use Encode;
_get_locale_encoding()
unless defined $locale_encoding;
croak "Cannot figure out an encoding to use"
unless defined $locale_encoding;
if ($locale_encoding =~ /^utf-?8$/i) {
$layer = "utf8";
} else {
$layer = "encoding($locale_encoding)";
}
} else {
unless(PerlIO::Layer::->find($layer)) {
carp("Unknown discipline layer '$layer'");
}
}
push(@val,":$layer");
if ($layer =~ /^(crlf|raw)$/) {
$^H{"open_$type"} = $layer;
}
}
# print "# type = $type, val = @val\n";
if ($type eq 'IN') {
$in = join(' ',@val);
}
elsif ($type eq 'OUT') {
$out = join(' ',@val);
}
elsif ($type eq 'IO') {
$in = $out = join(' ',@val);
}
else {
croak "Unknown discipline class '$type'";
}
}
${^OPEN} = join("\0",$in,$out);
}
1;
__END__
=head1 NAME
open - perl pragma to set default disciplines for input and output
=head1 SYNOPSIS
use open IN => ":crlf", OUT => ":raw";
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)';
=head1 DESCRIPTION
Full-fledged support for I/O disciplines 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" (aka disciplines) for all I/O.
The C<open> pragma is used to declare one or more default layers for
I/O operations. Any open(), readpipe() (aka qx//) and similar
operators found within the lexical scope of this pragma will use the
declared defaults.
With the C<IN> subpragma you can declare the default layers
of input sterams, 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 disciplines 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)';
When open() is given an explicit list of layers they are appended to
the list declared using this pragma.
Directory handles may also support disciplines in future.
=head1 NONPERLIO FUNCTIONALITY
If Perl is not built to use PerlIO as its IO system then only the two
pseudo-disciplines ":raw" and ":crlf" are available.
The ":raw" discipline corresponds to "binary mode" and the ":crlf"
discipline 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 disciplines 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
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