package open;
use warnings;
-use Carp;
-$open::hint_bits = 0x20000;
-our $VERSION = '1.01';
+our $VERSION = '1.12';
+
+require 5.008001; # for PerlIO::get_layers()
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);
- }
- } 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_CN|chin(?:a|ese)?$/i) {
- $locale_encoding = 'euc-cn';
- } elsif ($country_language =~ /^zh_TW|taiwan(?:ese)?$/i) {
- $locale_encoding = 'euc-tw';
- }
- croak "Locale encoding 'euc' too ambiguous"
- if $locale_encoding eq 'euc';
- }
+sub _get_encname {
+ return ($1, Encode::resolve_alias($1)) if $_[0] =~ /^:?encoding\((.+)\)$/;
+ return;
+}
+
+sub croak {
+ require Carp; goto &Carp::croak;
+}
+
+sub _drop_oldenc {
+ # If by the time we arrive here there already is at the top of the
+ # perlio layer stack an encoding identical to what we would like
+ # to push via this open pragma, we will pop away the old encoding
+ # (+utf8) so that we can push ourselves in place (this is easier
+ # than ignoring pushing ourselves because of the way how ${^OPEN}
+ # works). So we are looking for something like
+ #
+ # stdio encoding(xxx) utf8
+ #
+ # in the existing layer stack, and in the new stack chunk for
+ #
+ # :encoding(xxx)
+ #
+ # If we find a match, we pop the old stack (once, since
+ # the utf8 is just a flag on the encoding layer)
+ my ($h, @new) = @_;
+ return unless @new >= 1 && $new[-1] =~ /^:encoding\(.+\)$/;
+ my @old = PerlIO::get_layers($h);
+ return unless @old >= 3 &&
+ $old[-1] eq 'utf8' &&
+ $old[-2] =~ /^encoding\(.+\)$/;
+ require Encode;
+ my ($loname, $lcname) = _get_encname($old[-2]);
+ unless (defined $lcname) { # Should we trust get_layers()?
+ croak("open: Unknown encoding '$loname'");
+ }
+ my ($voname, $vcname) = _get_encname($new[-1]);
+ unless (defined $vcname) {
+ croak("open: Unknown encoding '$voname'");
+ }
+ if ($lcname eq $vcname) {
+ binmode($h, ":pop"); # utf8 is part of the encoding layer
}
}
sub import {
my ($class,@args) = @_;
- croak("`use open' needs explicit list of disciplines") unless @args;
+ croak("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);
foreach my $layer (split(/\s+/,$dscp)) {
$layer =~ s/^://;
if ($layer eq 'locale') {
- use Encode;
- _get_locale_encoding()
+ require Encode;
+ require encoding;
+ $locale_encoding = encoding::_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)";
- }
+ $layer = "encoding($locale_encoding)";
$std = 1;
} else {
my $target = $layer; # the layer name itself
$target =~ s/^(\w+)\(.+\)$/$1/; # strip parameters
- unless(PerlIO::Layer::->find($target)) {
- warnings::warnif("layer", "Unknown discipline layer '$layer'");
+ unless(PerlIO::Layer::->find($target,1)) {
+ warnings::warnif("layer", "Unknown PerlIO layer '$target'");
}
}
push(@val,":$layer");
}
}
if ($type eq 'IN') {
- $in = join(' ',@val);
+ _drop_oldenc(*STDIN, @val) if $std;
+ $in = join(' ', @val);
}
elsif ($type eq 'OUT') {
- $out = join(' ',@val);
+ if ($std) {
+ _drop_oldenc(*STDOUT, @val);
+ _drop_oldenc(*STDERR, @val);
+ }
+ $out = join(' ', @val);
}
elsif ($type eq 'IO') {
- $in = $out = join(' ',@val);
+ if ($std) {
+ _drop_oldenc(*STDIN, @val);
+ _drop_oldenc(*STDOUT, @val);
+ _drop_oldenc(*STDERR, @val);
+ }
+ $in = $out = join(' ', @val);
}
else {
- croak "Unknown discipline class '$type'";
+ croak "Unknown PerlIO layer class '$type' (need IN, OUT or IO)";
}
}
- ${^OPEN} = join("\0",$in,$out) if $in or $out;
+ ${^OPEN} = join("\0", $in, $out);
if ($std) {
if ($in) {
if ($in =~ /:utf8\b/) {
=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 => ":crlf", OUT => ":raw";
- use open OUT => ':utf8';
- use open IO => ":encoding(iso-8859-7)";
+ use open IN => ':crlf', OUT => ':raw';
+ open my $in, '<', 'foo.txt' or die "open failed: $!";
+ my $line = <$in>; # CRLF translated
+ close $in;
+ open my $out, '>', 'bar.txt' or die "open failed: $!";
+ print $out $line; # no translation of bytes
+ close $out;
+
+ use open OUT => ':encoding(UTF-8)';
+ use open IN => ':encoding(iso-8859-7)';
use open IO => ':locale';
- use open ':utf8';
- use open ':locale';
+ # IO implicit only for :utf8, :encoding, :locale
+ use open ':encoding(UTF-8)';
use open ':encoding(iso-8859-7)';
+ use open ':locale';
- use open ':std';
+ # with :std, also affect global standard handles
+ use open ':std', ':encoding(UTF-8)';
+ use open ':std', OUT => ':encoding(cp1252)';
+ use open ':std', IO => ':raw :encoding(UTF-16LE)';
=head1 DESCRIPTION
-Full-fledged support for I/O disciplines is now implemented provided
-Perl is configured to use PerlIO as its IO system (which is now the
-default).
+Full-fledged support for I/O layers is now implemented provided
+Perl is configured to use PerlIO as its IO system (which has been the
+default since 5.8, and the only supported configuration since 5.16).
The C<open> pragma serves as one of the interfaces to declare default
-"layers" (aka disciplines) for all I/O.
+"layers" (previously known as "disciplines") for all I/O. Any open(),
+readpipe() (aka qx//) and similar operators found within the
+lexical scope of this pragma will use the declared defaults via the
+L<C<${^OPEN}>|perlvar/${^OPEN}> variable.
-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.
+Layers are specified with a leading colon by convention. You can
+specify a stack of multiple layers as a space-separated string.
+See L<PerlIO> for more information on the available layers.
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 disciplines based on your
-locale environment variables, you can use the C<:locale> tag.
+the default layers of output streams. With the C<IO> subpragma
+(may be omitted for C<:utf8>, C<:locale>, or C<:encoding>) you
+can control both input and output streams simultaneously.
+
+When open() is given an explicit list of layers (with the three-arg
+syntax), they override the list declared using this pragma. open() can
+also be given a single colon (:) for a layer name, to override this pragma
+and use the default as detailed in
+L<PerlIO/Defaults and how to override them>.
+
+To translate from and to an arbitrary text encoding, use the C<:encoding>
+layer. The matching of encoding names in C<:encoding> is loose: case does
+not matter, and many encodings have several aliases. See
+L<Encode::Supported> for details and the list of supported locales.
+
+If you want to set your encoding layers based on your
+locale environment variables, you can use the C<:locale> pseudo-layer.
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> discipline 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 (LANGUAGE, 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 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.
+ open(my $out, '>', 'koi8') or die "open failed: $!";
+ print $out chr(0x430); # CYRILLIC SMALL LETTER A = KOI8-R 0xc1
+ close $out;
+ open(my $in, '<', 'koi8') or die "open failed: $!";
+ printf "%#x\n", ord(<$in>); # this should print 0xc1
+ close $in;
+
+The logic of C<:locale> is described in full in
+L<encoding/The C<:locale> sub-pragma>,
+but in short it is first trying nl_langinfo(CODESET) and then
+guessing from the LC_ALL and LANG locale environment variables.
+C<:locale> also implicitly turns on C<:std>.
+
+C<:std> is not a layer but an additional subpragma. When specified in the
+import list, it activates an additional functionality of pushing the
+layers selected for input/output handles to the standard filehandles
+(STDIN, STDOUT, STDERR). If the new layers and existing layer stack both
+end with an C<:encoding> layer, the existing C<:encoding> layer will also
+be removed.
+
+For example, if both input and out are chosen to be C<:encoding(UTF-8)>, a
+C<:std> will mean that STDIN, STDOUT, and STDERR will also have
+C<:encoding(UTF-8)> set. 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 effect of C<:std> is not lexical as it modifies the layer stack of the
+global handles. If you wish to apply only this global effect and not the
+effect on handles that are opened in that scope, you can isolate the call
+to this pragma in its own lexical scope.
+
+ { use open ':std', IO => ':encoding(UTF-8)' }
=head1 IMPLEMENTATION DETAILS
https://perl5.git.perl.org / perl5.git / blobdiff