Add a pseudolayer ":locale" to the open pragma which

will get the encoding from the locale.  Yet undocumented
because I can't get the PerlIO :encoding(foobar) to work.

p4raw-id: //depot/perl@11236

2 files changed, 47 insertions, 9 deletions

diff --git a/ext/Encode/Encode.pm b/ext/Encode/Encode.pm
index a274f387bf..4e55f46286 100644
--- a/ext/Encode/Encode.pm
+++ b/ext/Encode/Encode.pm
@@ -102,17 +102,14 @@ sub define_alias
 # Allow variants of iso-8859-1 etc.
 define_alias( qr/^iso[-_]?(\d+)[-_](\d+)$/i => '"iso-$1-$2"' );
 
-# This is a font issue, not an encoding issue.
-# (The currency symbol of the Latin 1 upper half is redefined
-# as the euro symbol.)
-define_alias( qr/^(.+)\@euro$/i => '"$1"' );
-
-# Solaris has this as a generic Latin-1 encoding.
-define_alias( qr/^iso_8859_1$/ => 'iso-8859-1' );
-
 # At least HP-UX has these.
 define_alias( qr/^iso8859(\d+)$/i => '"iso-8859-$1"' );
 
+# This is a font issue, not an encoding issue.
+# (The currency symbol of the Latin 1 upper half
+#  has been redefined as the euro symbol.)
+define_alias( qr/^(.+)\@euro$/i => '"$1"' );
+
 # Allow latin-1 style names as well
 define_alias( qr/^(?:iso[-_]?)?latin[-_]?(\d+)$/i => '"iso-8859-$latin2iso_num[$1]"' );
 
@@ -126,9 +123,15 @@ define_alias( 'ascii'    => 'US-ascii',
 # At least AIX has IBM-NNN (surprisingly...) instead of cpNNN.
 define_alias( qr/^ibm[-_]?(\d\d\d\d?)$/i => '"cp$1"');
 
-# Standardize on the dashed version.
+# Standardize on the dashed versions.
+define_alias( qr/^utf8$/i  => 'utf-8' );
 define_alias( qr/^koi8r$/i => 'koi8-r' );
 
+# TODO: the HP-UX '8' encodings:  arabic8 greek8 hebrew8 roman8 turkish8
+# TODO: the Thai Encoding tis620
+# TODO: the Chinese Encoding gb18030
+# TODO: what is the Japanese 'ujis' encoding seen in some Linuxes?
+
 # Map white space and _ to '-'
 define_alias( qr/^(\S+)[\s_]+(.*)$/i => '"$1-$2"' );
 
diff --git a/lib/open.pm b/lib/open.pm
index 3a08b797fd..085e770162 100644
--- a/lib/open.pm
+++ b/lib/open.pm
@@ -4,6 +4,33 @@ $open::hint_bits = 0x20000;
 
 our $VERSION = '1.01';
 
+my $locale_encoding;
+
+sub in_locale { $^H & $locale::hint_bits }
+
+sub _get_locale_encoding {
+    unless (defined $locale_encoding) {
+	eval { use I18N::Langinfo qw(langinfo CODESET) };
+	unless ($@) {
+	    $locale_encoding = langinfo(CODESET);
+	}
+        if (not $locale_encoding && in_locale()) {
+	    if ($ENV{LC_ALL} =~ /^[^.]+\.([^.]+)$/) {
+		$locale_encoding = $1;
+	    } elsif ($ENV{LANG} =~ /^[^.]+\.([^.]+)$/) {
+		$locale_encoding = $1;
+	    }
+	} else {
+	    # Could do heuristics based on the country and language
+	    # parts of LC_ALL and LANG (the parts before the dot (if any)),
+	    # since we have Locale::Country and Locale::Language available.
+	    # TODO: get a database of Language -> Encoding mappings
+	    # (the Estonian database would be excellent!)
+	    # --jhi
+	}
+    }
+}
+
 sub import {
     my ($class,@args) = @_;
     croak("`use open' needs explicit list of disciplines") unless @args;
@@ -17,6 +44,14 @@ sub import {
 	my @val;
 	foreach my $layer (split(/\s+/,$discp)) {
             $layer =~ s/^://;
+	    if ($layer eq 'locale') {
+		use Encode;
+		_get_locale_encoding()
+		    unless defined $locale_encoding;
+		croak "Cannot figure out an encoding to use"
+		    unless defined $locale_encoding;
+		$layer = "encoding($locale_encoding)";
+	    }
 	    unless(PerlIO::Layer::->find($layer)) {
 		carp("Unknown discipline layer '$layer'");
 	    }