X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Futf8.pm;h=b18a043f10d31fd4e7eec31b42d16e313c4b4375;hb=13a6c0e08df522ae430c77e8a15932642751b605;hp=35be28caa796ab6967048950d475c27963e7e186;hpb=daf4d4ea57f31fbfc23438d8d6f6bb9c48b870bd;p=p5sagit%2Fp5-mst-13.2.git

diff --git a/lib/utf8.pm b/lib/utf8.pm
index 35be28c..b18a043 100644
--- a/lib/utf8.pm
+++ b/lib/utf8.pm
@@ -2,6 +2,8 @@ package utf8;
 
 $utf8::hint_bits = 0x00800000;
 
+our $VERSION = '1.00';
+
 sub import {
     $^H |= $utf8::hint_bits;
     $enc{caller()} = $_[1] if $_[1];
@@ -22,7 +24,7 @@ __END__
 
 =head1 NAME
 
-utf8 - Perl pragma to enable/disable UTF-8 in source code
+utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code
 
 =head1 SYNOPSIS
 
@@ -31,13 +33,10 @@ utf8 - Perl pragma to enable/disable UTF-8 in source code
 
 =head1 DESCRIPTION
 
-WARNING: The implementation of Unicode support in Perl is incomplete.
-See L<perlunicode> for the exact details.
-
 The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
-program text in the current lexical scope.  The C<no utf8> pragma
-tells Perl to switch back to treating the source text as literal
-bytes in the current lexical scope.
+program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based
+platforms).  The C<no utf8> pragma tells Perl to switch back to treating 
+the source text as literal bytes in the current lexical scope.
 
 This pragma is primarily a compatibility device.  Perl versions
 earlier than 5.6 allowed arbitrary bytes in source code, whereas
@@ -45,31 +44,71 @@ in future we would like to standardize on the UTF-8 encoding for
 source text.  Until UTF-8 becomes the default format for source
 text, this pragma should be used to recognize UTF-8 in the source.
 When UTF-8 becomes the standard source format, this pragma will
-effectively become a no-op.
+effectively become a no-op.  For convenience in what follows the
+term I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based
+platforms and UTF-EBCDIC on EBCDIC based platforms.
 
-Enabling the C<utf8> pragma has the following effects:
+Enabling the C<utf8> pragma has the following effect:
 
-=over
+=over 4
 
 =item *
 
 Bytes in the source text that have their high-bit set will be treated
-as being part of a literal UTF-8 character.  This includes most literals
-such as identifiers, string constants, constant regular expression patterns
-and package names.
+as being part of a literal UTF-8 character.  This includes most
+literals such as identifiers, string constants, constant regular
+expression patterns and package names.  On EBCDIC platforms characters
+in the Latin 1 character set are treated as being part of a literal
+UTF-EBCDIC character.
 
-=item *
+=back
+
+Note that if you have bytes with the eighth bit on in your script
+(for example embedded Latin-1 in your string literals), C<use utf8>
+will be unhappy since the bytes are most probably not well-formed
+UTF-8.  If you want to have such bytes and use utf8, you can disable
+utf8 until the end the block (or file, if at top level) by C<no utf8;>.
+
+=head2 Utility functions
+
+The following functions are defined in the C<utf8::> package by the perl core.
+
+=over 4
+
+=item * $num_octets = utf8::upgrade($string);
+
+Converts internal representation of string to the Perl's internal
+I<UTF-X> form.  Returns the number of octets necessary to represent
+the string as I<UTF-X>.  Note that this should not be used to convert
+a legacy byte encoding to Unicode: use Encode for that.  Affected
+by the encoding pragma.
+
+=item * utf8::downgrade($string[, CHECK])
+
+Converts internal representation of string to be un-encoded bytes.
+Note that this should not be used to convert Unicode back to a legacy
+byte encoding: use Encode for that.  B<Not> affected by the encoding
+pragma.
+
+=item * utf8::encode($string)
+
+Converts (in-place) I<$string> from logical characters to octet
+sequence representing it in Perl's I<UTF-X> encoding.  Note that this
+should not be used to convert a legacy byte encoding to Unicode: use
+Encode for that.  =item * $flag = utf8::decode($string)
+
+Attempts to convert I<$string> in-place from Perl's I<UTF-X> encoding
+into logical characters.  Note that this should not be used to convert
+Unicode back to a legacy byte encoding: use Encode for that.
 
-In the absence of inputs marked as UTF-8, regular expressions within the
-scope of this pragma will default to using character semantics instead
-of byte semantics.
+=back
 
-    @bytes_or_chars = split //, $data;	# may split to bytes if data
-					# $data isn't UTF-8
-    {
-	use utf8;			# force char semantics
-	@chars = split //, $data;	# splits characters
-    }
+C<utf8::encode> is like C<utf8::upgrade> but the UTF8 flag does not
+get turned on. See L<perlunicode> for more on the UTF8 flag and the C
+API functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>,
+C<sv_utf8_encode>, C<sv_utf8_decode> that are wrapped by the Perl
+functions C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
+C<utf8::decode>.
 
 =head1 SEE ALSO