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 disciplines for input and output
+open - perl pragma to set default PerlIO layers for input and output
=head1 SYNOPSIS
- use open IN => ":any", OUT => ":utf8"; # unimplemented
+ 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
-NOTE: This pragma is not yet implemented.
+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';
-The open pragma is used to declare one or more default disciplines for
-I/O operations. Any constructors for file, socket, pipe, or directory
-handles found within the lexical scope of this pragma will use the
-declared default.
+and these
-Handle constructors that are called with an explicit set of disciplines
-are not influenced by the declared defaults.
+ use open ':encoding(iso-8859-7)';
+ use open IO => ':encoding(iso-8859-7)';
-The default disciplines so declared are available by the special
-discipline name ":def", and can be used within handle constructors
-that allow disciplines to be specified. This makes it possible to
-stack new disciplines over the default ones.
+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.
- open FH, "<:para :def", $file or die "can't open $file: $!";
+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<perlunicode>, L<perlfunc/"open">
+L<perlfunc/"binmode">, L<perlfunc/"open">, L<perlunicode>, L<PerlIO>,
+L<encoding>
=cut
-
-1;
projects / p5sagit/p5-mst-13.2.git / blobdiff