X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Futf8.pm;h=b7c938e17eda0774f56440f5cd87a1f434d541e6;hb=06c0cc96ebd866767a6d107ed78967600f7e0395;hp=d9e9becdda5c9e5917296d33566132db3868c209;hpb=3969a89698ec7136fcf0eb1062fdf63f0e7726f4;p=p5sagit%2Fp5-mst-13.2.git

diff --git a/lib/utf8.pm b/lib/utf8.pm
index d9e9bec..b7c938e 100644
--- a/lib/utf8.pm
+++ b/lib/utf8.pm
@@ -1,17 +1,23 @@
 package utf8;
 
+$utf8::hint_bits = 0x00800000;
+
+our $VERSION = '1.05';
+
 sub import {
-    $^H |= 0x00800000;
+    $^H |= $utf8::hint_bits;
     $enc{caller()} = $_[1] if $_[1];
 }
 
 sub unimport {
-    $^H &= ~0x00800000;
+    $^H &= ~$utf8::hint_bits;
 }
 
 sub AUTOLOAD {
     require "utf8_heavy.pl";
-    goto &$AUTOLOAD;
+    goto &$AUTOLOAD if defined &$AUTOLOAD;
+    require Carp;
+    Carp::croak("Undefined subroutine $AUTOLOAD called");
 }
 
 1;
@@ -19,57 +25,190 @@ __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
 
     use utf8;
     no utf8;
 
-=head1 DESCRIPTION
+    # Convert a Perl scalar to/from UTF-8.
+    $num_octets = utf8::upgrade($string);
+    $success    = utf8::downgrade($string[, FAIL_OK]);
 
-WARNING: The implementation of Unicode support in Perl is incomplete.
-Expect sudden and unannounced changes!
+    # Change the native bytes of a Perl scalar to/from UTF-8 bytes.
+    utf8::encode($string);
+    utf8::decode($string);
+
+    $flag = utf8::is_utf8(STRING); # since Perl 5.8.1
+    $flag = utf8::valid(STRING);
+
+=head1 DESCRIPTION
 
 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
 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.
+source text.
 
-Enabling the C<utf8> pragma has the following effects:
+B<Do not use this pragma for anything else than telling Perl that your
+script is written in UTF-8.> The utility functions described below are
+useful for their own purposes, but they are not really part of the
+"pragmatic" effect.
 
-=over
+Until UTF-8 becomes the default format for source text, either this
+pragma or the L</encoding> 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.  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.
+
+See also the effects of the C<-C> switch and its cousin, the
+C<$ENV{PERL_UNICODE}>, in L<perlrun>.
+
+Enabling the C<utf8> pragma has the following effect:
+
+=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 identifier names, string constants, and constant
+regular expression patterns.
 
-=item *
+On EBCDIC platforms characters in the Latin 1 character set are
+treated as being part of a literal UTF-EBCDIC character.
+
+=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;>.
+
+If you want to automatically upgrade your 8-bit legacy bytes to UTF-8,
+use the L</encoding> pragma instead of this pragma.  For example, if
+you want to implicitly upgrade your ISO 8859-1 (Latin-1) bytes to UTF-8
+as used in e.g. C<chr()> and C<\x{...}>, try this:
+
+    use encoding "latin-1";
+    my $c = chr(0xc4);
+    my $x = "\x{c5}";
+
+In case you are wondering: yes, C<use encoding 'utf8';> works much
+the same as C<use utf8;>.
+
+=head2 Utility functions
+
+The following functions are defined in the C<utf8::> package by the
+Perl core.  You do not need to say C<use utf8> to use these and in fact
+you should not say that  unless you really want to have UTF-8 source code.
+
+=over 4
+
+=item * $num_octets = utf8::upgrade($string)
+
+Converts in-place the octet sequence in the native encoding
+(Latin-1 or EBCDIC) to the equivalent character sequence in I<UTF-X>.
+I<$string> already encoded as characters does no harm.
+Returns the number of octets necessary to represent the string as I<UTF-X>.
+Can be used to make sure that the UTF-8 flag is on,
+so that C<\w> or C<lc()> work as Unicode on strings
+containing characters in the range 0x80-0xFF (on ASCII and
+derivatives).
+
+B<Note that this function does not handle arbitrary encodings.>
+Therefore I<Encode.pm> is recommended for the general purposes.
+
+Affected by the encoding pragma.
+
+=item * $success = utf8::downgrade($string[, FAIL_OK])
+
+Converts in-place the character sequence in I<UTF-X>
+to the equivalent octet sequence in the native encoding (Latin-1 or EBCDIC).
+I<$string> already encoded as octets does no harm.
+Returns true on success. On failure dies or, if the value of
+C<FAIL_OK> is true, returns false.
+Can be used to make sure that the UTF-8 flag is off,
+e.g. when you want to make sure that the substr() or length() function
+works with the usually faster byte algorithm.
+
+B<Note that this function does not handle arbitrary encodings.>
+Therefore I<Encode.pm> is recommended for the general purposes.
+
+B<Not> affected by the encoding pragma.
+
+B<NOTE:> this function is experimental and may change
+or be removed without notice.
+
+=item * utf8::encode($string)
+
+Converts in-place the character sequence to the corresponding octet sequence
+in I<UTF-X>.  The UTF-8 flag is turned off.  Returns nothing.
+
+B<Note that this function does not handle arbitrary encodings.>
+Therefore I<Encode.pm> is recommended for the general purposes.
+
+=item * utf8::decode($string)
+
+Attempts to convert in-place the octet sequence in I<UTF-X>
+to the corresponding character sequence.  The UTF-8 flag is turned on
+only if the source string contains multiple-byte I<UTF-X> characters.
+If I<$string> is invalid as I<UTF-X>, returns false; otherwise returns true.
+
+B<Note that this function does not handle arbitrary encodings.>
+Therefore I<Encode.pm> is recommended for the general purposes.
+
+B<NOTE:> this function is experimental and may change
+or be removed without notice.
+
+=item * $flag = utf8::is_utf8(STRING)
+
+(Since Perl 5.8.1)  Test whether STRING is in UTF-8.  Functionally
+the same as Encode::is_utf8().
+
+=item * $flag = utf8::valid(STRING)
+
+[INTERNAL] Test whether STRING is in a consistent state regarding
+UTF-8.  Will return true is well-formed UTF-8 and has the UTF-8 flag
+on B<or> if string is held as bytes (both these states are 'consistent').
+Main reason for this routine is to allow Perl's testsuite to check
+that operations have left strings in a consistent state.  You most
+probably want to use utf8::is_utf8() instead.
+
+=back
+
+C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is
+cleared.  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>,
+and C<sv_utf8_decode>, which are wrapped by the Perl functions
+C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
+C<utf8::decode>.  Note that in the Perl 5.8.0 and 5.8.1 implementation
+the functions utf8::is_utf8, utf8::valid, utf8::encode, utf8::decode,
+utf8::upgrade, and utf8::downgrade are always available, without a
+C<require utf8> statement-- this may change in future releases.
+
+=head1 BUGS
 
-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.
+One can have Unicode in identifier names, but not in package/class or
+subroutine names.  While some limited functionality towards this does
+exist as of Perl 5.8.0, that is more accidental than designed; use of
+Unicode for the said purposes is unsupported.
 
-    @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
-    }
+One reason of this unfinishedness is its (currently) inherent
+unportability: since both package names and subroutine names may need
+to be mapped to file and directory names, the Unicode capability of
+the filesystem becomes important-- and there unfortunately aren't
+portable answers.
 
 =head1 SEE ALSO
 
-L<perlunicode>, L<byte>
+L<perluniintro>, L<encoding>, L<perlrun>, L<bytes>, L<perlunicode>
 
 =cut