[Encode] 1.74 released -- final for 5.8.0-RC1

[perl5.git] / ext / Encode / Encode.pm

diff --git a/ext/Encode/Encode.pm b/ext/Encode/Encode.pm
index a828d46..0f57a03 100644 (file)
--- a/ext/Encode/Encode.pm
+++ b/ext/Encode/Encode.pm
@@ -1,63 +1,80 @@
+#
+# $Id: Encode.pm,v 1.74 2002/05/28 18:33:54 dankogai Exp dankogai $
+#

 package Encode;
 use strict;
 package Encode;
 use strict;

-our $VERSION = do { my @r = (q$Revision: 1.31 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
+our $VERSION = do { my @r = (q$Revision: 1.74 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };

 our $DEBUG = 0;
 our $DEBUG = 0;

+use XSLoader ();
+XSLoader::load(__PACKAGE__, $VERSION);

 
 

-require DynaLoader;

 require Exporter;
 require Exporter;

-
-our @ISA = qw(Exporter DynaLoader);
+use base qw/Exporter/;

 
 # Public, encouraged API is exported by default
 
 # Public, encouraged API is exported by default

-our @EXPORT = qw (
-  encode
-  decode
-  encode_utf8
-  decode_utf8
-  find_encoding
-  encodings
+
+our @EXPORT = qw(
+  decode  decode_utf8  encode  encode_utf8
+  encodings  find_encoding

 );
 
 );
 

+our @FB_FLAGS  = qw(DIE_ON_ERR WARN_ON_ERR RETURN_ON_ERR LEAVE_SRC
+                   PERLQQ HTMLCREF XMLCREF);
+our @FB_CONSTS = qw(FB_DEFAULT FB_CROAK FB_QUIET FB_WARN
+                   FB_PERLQQ FB_HTMLCREF FB_XMLCREF);
+

 our @EXPORT_OK =
 our @EXPORT_OK =

-    qw(
-       define_encoding
-       from_to
-       is_utf8
-       is_8bit
-       is_16bit
-       utf8_upgrade
-       utf8_downgrade
-       _utf8_on
-       _utf8_off
-      );
-
-bootstrap Encode ();
+    (
+     qw(
+       _utf8_off _utf8_on define_encoding from_to is_16bit is_8bit
+       is_utf8 perlio_ok resolve_alias utf8_downgrade utf8_upgrade
+      ),
+     @FB_FLAGS, @FB_CONSTS,
+    );
+
+our %EXPORT_TAGS =
+    (
+     all          =>  [ @EXPORT, @EXPORT_OK ],
+     fallbacks    =>  [ @FB_CONSTS ],
+     fallback_all =>  [ @FB_CONSTS, @FB_FLAGS ],
+    );

 
 # Documentation moved after __END__ for speed - NI-S
 
 
 # Documentation moved after __END__ for speed - NI-S
 

-use Carp;
-

 our $ON_EBCDIC = (ord("A") == 193);
 
 use Encode::Alias;
 
 # Make a %Encoding package variable to allow a certain amount of cheating
 our %Encoding;
 our $ON_EBCDIC = (ord("A") == 193);
 
 use Encode::Alias;
 
 # Make a %Encoding package variable to allow a certain amount of cheating
 our %Encoding;

-use Encode::Config;
+our %ExtModule;
+require Encode::Config;
+eval { require Encode::ConfigLocal };

 
 sub encodings
 {
     my $class = shift;
 
 sub encodings
 {
     my $class = shift;

-    my @modules = (@_ and $_[0] eq ":all") ? values %ExtModule : @_;
-    for my $mod (@modules){
-       $mod =~ s,::,/,g or $mod = "Encode/$mod";
-       $mod .= '.pm'; 
-       $DEBUG and warn "about to require $mod;";
-       eval { require $mod; };
+    my %enc;
+    if (@_ and $_[0] eq ":all"){
+       %enc = ( %Encoding, %ExtModule );
+    }else{
+       %enc = %Encoding;
+       for my $mod (map {m/::/o ? $_ : "Encode::$_" } @_){
+           $DEBUG and warn $mod;
+           for my $enc (keys %ExtModule){
+               $ExtModule{$enc} eq $mod and $enc{$enc} = $mod;
+           }
+       }

     }
     }

-    my %modules = map {$_ => 1} @modules;

     return
     return

-       sort grep {!/^(?:Internal|Unicode)$/o} keys %Encoding;
+       sort { lc $a cmp lc $b }
+             grep {!/^(?:Internal|Unicode|Guess)$/o} keys %enc;
+}
+
+sub perlio_ok{
+    my $obj = ref($_[0]) ? $_[0] : find_encoding($_[0]);
+    $obj->can("perlio_ok") and return $obj->perlio_ok();
+    return 0; # safety net

 }
 
 sub define_encoding
 }
 
 sub define_encoding


@@ -67,44 +84,33 @@ sub define_encoding
     $Encoding{$name} = $obj;
     my $lc = lc($name);
     define_alias($lc => $obj) unless $lc eq $name;
     $Encoding{$name} = $obj;
     my $lc = lc($name);
     define_alias($lc => $obj) unless $lc eq $name;

-    while (@_)
-    {
+    while (@_){

        my $alias = shift;
        my $alias = shift;

-       define_alias($alias,$obj);
+       define_alias($alias, $obj);

     }
     return $obj;
 }
 
 sub getEncoding
 {
     }
     return $obj;
 }
 
 sub getEncoding
 {

-    my ($class,$name,$skip_external) = @_;
-    my $enc;
-    if (ref($name) && $name->can('new_sequence'))
-    {
-       return $name;
-    }
+    my ($class, $name, $skip_external) = @_;
+
+    ref($name) && $name->can('new_sequence') and return $name;
+    exists $Encoding{$name} and return $Encoding{$name};

     my $lc = lc $name;
     my $lc = lc $name;

-    if (exists $Encoding{$name})
-    {
-       return $Encoding{$name};
-    }
-    if (exists $Encoding{$lc})
-    {
-       return $Encoding{$lc};
-    }
+    exists $Encoding{$lc} and return $Encoding{$lc};

 
     my $oc = $class->find_alias($name);
 
     my $oc = $class->find_alias($name);

-    return $oc if defined $oc;
-
-    $oc = $class->find_alias($lc) if $lc ne $name;
-    return $oc if defined $oc;
+    defined($oc) and return $oc;
+    $lc ne $name and $oc = $class->find_alias($lc);
+    defined($oc) and return $oc;

 
     unless ($skip_external)
     {
        if (my $mod = $ExtModule{$name} || $ExtModule{$lc}){
            $mod =~ s,::,/,g ; $mod .= '.pm';
            eval{ require $mod; };
 
     unless ($skip_external)
     {
        if (my $mod = $ExtModule{$name} || $ExtModule{$lc}){
            $mod =~ s,::,/,g ; $mod .= '.pm';
            eval{ require $mod; };

-           return $Encoding{$name} if exists $Encoding{$name};
+           exists $Encoding{$name} and return $Encoding{$name};

        }
     }
     return;
        }
     }
     return;


@@ -112,37 +118,58 @@ sub getEncoding
 
 sub find_encoding
 {
 
 sub find_encoding
 {

-    my ($name,$skip_external) = @_;
+    my ($name, $skip_external) = @_;

     return __PACKAGE__->getEncoding($name,$skip_external);
 }
 
     return __PACKAGE__->getEncoding($name,$skip_external);
 }
 

-sub encode
+sub resolve_alias {
+    my $obj = find_encoding(shift);
+    defined $obj and return $obj->name;
+    return;
+}
+
+sub encode($$;$)

 {
 {

-    my ($name,$string,$check) = @_;
+    my ($name, $string, $check) = @_;
+    $check ||=0;

     my $enc = find_encoding($name);
     my $enc = find_encoding($name);

-    croak("Unknown encoding '$name'") unless defined $enc;
+    unless(defined $enc){
+       require Carp;
+       Carp::croak("Unknown encoding '$name'");
+    }

     my $octets = $enc->encode($string,$check);
     return undef if ($check && length($string));
     return $octets;
 }
 
     my $octets = $enc->encode($string,$check);
     return undef if ($check && length($string));
     return $octets;
 }
 

-sub decode
+sub decode($$;$)

 {
     my ($name,$octets,$check) = @_;
 {
     my ($name,$octets,$check) = @_;

+    $check ||=0;

     my $enc = find_encoding($name);
     my $enc = find_encoding($name);

-    croak("Unknown encoding '$name'") unless defined $enc;
+    unless(defined $enc){
+       require Carp;
+       Carp::croak("Unknown encoding '$name'");
+    }

     my $string = $enc->decode($octets,$check);
     $_[1] = $octets if $check;
     return $string;
 }
 
     my $string = $enc->decode($octets,$check);
     $_[1] = $octets if $check;
     return $string;
 }
 

-sub from_to
+sub from_to($$$;$)

 {
     my ($string,$from,$to,$check) = @_;
 {
     my ($string,$from,$to,$check) = @_;

+    $check ||=0;

     my $f = find_encoding($from);
     my $f = find_encoding($from);

-    croak("Unknown encoding '$from'") unless defined $f;
+    unless (defined $f){
+       require Carp;
+       Carp::croak("Unknown encoding '$from'");
+    }

     my $t = find_encoding($to);
     my $t = find_encoding($to);

-    croak("Unknown encoding '$to'") unless defined $t;
+    unless (defined $t){
+       require Carp;
+       Carp::croak("Unknown encoding '$to'");
+    }

     my $uni = $f->decode($string,$check);
     return undef if ($check && length($string));
     $string =  $t->encode($uni,$check);
     my $uni = $f->decode($string,$check);
     return undef if ($check && length($string));
     $string =  $t->encode($uni,$check);


@@ -150,14 +177,14 @@ sub from_to
     return defined($_[0] = $string) ? length($string) : undef ;
 }
 
     return defined($_[0] = $string) ? length($string) : undef ;
 }
 

-sub encode_utf8
+sub encode_utf8($)

 {
     my ($str) = @_;
     utf8::encode($str);
     return $str;
 }
 
 {
     my ($str) = @_;
     utf8::encode($str);
     return $str;
 }
 

-sub decode_utf8
+sub decode_utf8($)

 {
     my ($str) = @_;
     return undef unless utf8::decode($str);
 {
     my ($str) = @_;
     return undef unless utf8::decode($str);


@@ -169,17 +196,18 @@ predefine_encodings();
 #
 # This is to restore %Encoding if really needed;
 #
 #
 # This is to restore %Encoding if really needed;
 #

+

 sub predefine_encodings{
 sub predefine_encodings{

-    if ($ON_EBCDIC) { 
+    use Encode::Encoding;
+    if ($ON_EBCDIC) {

        # was in Encode::UTF_EBCDIC
        package Encode::UTF_EBCDIC;
        # was in Encode::UTF_EBCDIC
        package Encode::UTF_EBCDIC;

-       *name         = sub{ shift->{'Name'} };
-       *new_sequence = sub{ return $_[0] };
+       push @Encode::UTF_EBCDIC::ISA, 'Encode::Encoding';

        *decode = sub{
            my ($obj,$str,$chk) = @_;
            my $res = '';
            for (my $i = 0; $i < length($str); $i++) {
        *decode = sub{
            my ($obj,$str,$chk) = @_;
            my $res = '';
            for (my $i = 0; $i < length($str); $i++) {

-               $res .= 
+               $res .=

                    chr(utf8::unicode_to_native(ord(substr($str,$i,1))));
            }
            $_[1] = '' if $chk;
                    chr(utf8::unicode_to_native(ord(substr($str,$i,1))));
            }
            $_[1] = '' if $chk;


@@ -189,19 +217,17 @@ sub predefine_encodings{
            my ($obj,$str,$chk) = @_;
            my $res = '';
            for (my $i = 0; $i < length($str); $i++) {
            my ($obj,$str,$chk) = @_;
            my $res = '';
            for (my $i = 0; $i < length($str); $i++) {

-               $res .= 
+               $res .=

                    chr(utf8::native_to_unicode(ord(substr($str,$i,1))));
            }
            $_[1] = '' if $chk;
            return $res;
        };
                    chr(utf8::native_to_unicode(ord(substr($str,$i,1))));
            }
            $_[1] = '' if $chk;
            return $res;
        };

-       $Encode::Encoding{Internal} = 
+       $Encode::Encoding{Unicode} =

            bless {Name => "UTF_EBCDIC"} => "Encode::UTF_EBCDIC";
            bless {Name => "UTF_EBCDIC"} => "Encode::UTF_EBCDIC";

-    } else {  
-       # was in Encode::UTF_EBCDIC
+    } else {

        package Encode::Internal;
        package Encode::Internal;

-       *name         = sub{ shift->{'Name'} };
-       *new_sequence = sub{ return $_[0] };
+       push @Encode::Internal::ISA, 'Encode::Encoding';

        *decode = sub{
            my ($obj,$str,$chk) = @_;
            utf8::upgrade($str);
        *decode = sub{
            my ($obj,$str,$chk) = @_;
            utf8::upgrade($str);


@@ -209,15 +235,14 @@ sub predefine_encodings{
            return $str;
        };
        *encode = \&decode;
            return $str;
        };
        *encode = \&decode;

-       $Encode::Encoding{Unicode} = 
+       $Encode::Encoding{Unicode} =

            bless {Name => "Internal"} => "Encode::Internal";
     }
 
     {
        # was in Encode::utf8
        package Encode::utf8;
            bless {Name => "Internal"} => "Encode::Internal";
     }
 
     {
        # was in Encode::utf8
        package Encode::utf8;

-       *name         = sub{ shift->{'Name'} };
-       *new_sequence = sub{ return $_[0] };
+       push @Encode::utf8::ISA, 'Encode::Encoding';

        *decode = sub{
            my ($obj,$octets,$chk) = @_;
            my $str = Encode::decode_utf8($octets);
        *decode = sub{
            my ($obj,$octets,$chk) = @_;
            my $str = Encode::decode_utf8($octets);


@@ -233,23 +258,11 @@ sub predefine_encodings{
            $_[1] = '' if $chk;
            return $octets;
        };
            $_[1] = '' if $chk;
            return $octets;
        };

-       $Encode::Encoding{utf8} = 
+       $Encode::Encoding{utf8} =

            bless {Name => "utf8"} => "Encode::utf8";
     }
            bless {Name => "utf8"} => "Encode::utf8";
     }

-    # do externals if necessary 
-    require File::Basename;
-    require File::Spec;
-    for my $ext (qw()){
-       my $pm =
-           File::Spec->catfile(File::Basename::dirname($INC{'Encode.pm'}),
-                               "Encode", "$ext.pm");
-       do $pm;
-    }

 }
 
 }
 

-require Encode::Encoding;
-require Encode::XS;
-

 1;
 
 __END__
 1;
 
 __END__


@@ -262,17 +275,16 @@ Encode - character encodings
 
     use Encode;
 
 
     use Encode;
 

-

 =head2 Table of Contents
 
 =head2 Table of Contents
 

-Encode consists of a collection of modules which details are too big 
+Encode consists of a collection of modules whose details are too big

 to fit in one document.  This POD itself explains the top-level APIs
 to fit in one document.  This POD itself explains the top-level APIs

-and general topics at a glance.  For other topics and more details, 
-see the PODs below;
+and general topics at a glance.  For other topics and more details,
+see the PODs below:

 
   Name                         Description
   --------------------------------------------------------
 
   Name                         Description
   --------------------------------------------------------

-  Encode::Alias         Alias defintions to encodings
+  Encode::Alias         Alias definitions to encodings

   Encode::Encoding      Encode Implementation Base Class
   Encode::Supported     List of Supported Encodings
   Encode::CN            Simplified Chinese Encodings
   Encode::Encoding      Encode Implementation Base Class
   Encode::Supported     List of Supported Encodings
   Encode::CN            Simplified Chinese Encodings


@@ -294,21 +306,21 @@ codepoint" for the character (the exceptions are those platforms where
 the legacy encoding is some variant of EBCDIC rather than a super-set
 of ASCII - see L<perlebcdic>).
 
 the legacy encoding is some variant of EBCDIC rather than a super-set
 of ASCII - see L<perlebcdic>).
 

-Traditionally computer data has been moved around in 8-bit chunks
+Traditionally, computer data has been moved around in 8-bit chunks

 often called "bytes". These chunks are also known as "octets" in
 networking standards. Perl is widely used to manipulate data of many
 types - not only strings of characters representing human or computer
 often called "bytes". These chunks are also known as "octets" in
 networking standards. Perl is widely used to manipulate data of many
 types - not only strings of characters representing human or computer

-languages but also "binary" data being the machines representation of
+languages but also "binary" data being the machine's representation of

 numbers, pixels in an image - or just about anything.
 
 numbers, pixels in an image - or just about anything.
 

-When Perl is processing "binary data" the programmer wants Perl to
+When Perl is processing "binary data", the programmer wants Perl to

 process "sequences of bytes". This is not a problem for Perl - as a
 process "sequences of bytes". This is not a problem for Perl - as a

-byte has 256 possible values it easily fits in Perl's much larger
+byte has 256 possible values, it easily fits in Perl's much larger

 "logical character".
 
 =head2 TERMINOLOGY
 
 "logical character".
 
 =head2 TERMINOLOGY
 

-=over 4
+=over 2

 
 =item *
 
 
 =item *
 


@@ -323,89 +335,104 @@ I<byte>: a character in the range 0..255
 =item *
 
 I<octet>: 8 bits of data, with ordinal values 0..255
 =item *
 
 I<octet>: 8 bits of data, with ordinal values 0..255

-(Term for bytes passed to or from a non-Perl context, e.g. disk file.)
+(Term for bytes passed to or from a non-Perl context, e.g. a disk file.)

 
 =back
 
 
 =back
 

-The marker [INTERNAL] marks Internal Implementation Details, in
-general meant only for those who think they know what they are doing,
-and such details may change in future releases.
-

 =head1 PERL ENCODING API
 
 =head1 PERL ENCODING API
 

-=over 4
+=over 2

 
 

-=item $octets  = encode(ENCODING, $string[, CHECK])
+=item $octets  = encode(ENCODING, $string [, CHECK])

 
 

-Encodes string from Perl's internal form into I<ENCODING> and returns
+Encodes a string from Perl's internal form into I<ENCODING> and returns

 a sequence of octets.  ENCODING can be either a canonical name or
 a sequence of octets.  ENCODING can be either a canonical name or

-alias.  For encoding names and aliases, see L</"Defining Aliases">.
-For CHECK see L</"Handling Malformed Data">.
+an alias.  For encoding names and aliases, see L</"Defining Aliases">.
+For CHECK, see L</"Handling Malformed Data">.
+
+For example, to convert a string from Perl's internal format to
+iso-8859-1 (also known as Latin1),

 
 

-For example to convert (internally UTF-8 encoded) Unicode string to
-iso-8859-1 (also known as Latin1), 
+  $octets = encode("iso-8859-1", $string);

 
 

-  $octets = encode("iso-8859-1", $unicode);
+B<CAVEAT>: When you run C<$octets = encode("utf8", $string)>, then $octets
+B<may not be equal to> $string.  Though they both contain the same data, the utf8 flag
+for $octets is B<always> off.  When you encode anything, utf8 flag of
+the result is always off, even when it contains completely valid utf8
+string. See L</"The UTF-8 flag"> below.

 
 

-=item $string = decode(ENCODING, $octets[, CHECK])
+encode($valid_encoding, undef) is harmless but warns you for 
+C<Use of uninitialized value in subroutine entry>. 
+encode($valid_encoding, '') is harmless and warnless.

 
 

-Decode sequence of octets assumed to be in I<ENCODING> into Perl's
-internal form and returns the resulting string.  as in encode(),
-ENCODING can be either a canonical name or alias. For encoding names
-and aliases, see L</"Defining Aliases">.  For CHECK see
+=item $string = decode(ENCODING, $octets [, CHECK])
+
+Decodes a sequence of octets assumed to be in I<ENCODING> into Perl's
+internal form and returns the resulting string.  As in encode(),
+ENCODING can be either a canonical name or an alias. For encoding names
+and aliases, see L</"Defining Aliases">.  For CHECK, see

 L</"Handling Malformed Data">.
 
 L</"Handling Malformed Data">.
 

-For example to convert ISO-8859-1 data to UTF-8:
+For example, to convert ISO-8859-1 data to a string in Perl's internal format:
+
+  $string = decode("iso-8859-1", $octets);

 
 

-  $utf8 = decode("iso-8859-1", $latin1);
+B<CAVEAT>: When you run C<$string = decode("utf8", $octets)>, then $string
+B<may not be equal to> $octets.  Though they both contain the same data,
+the utf8 flag for $string is on unless $octets entirely consists of
+ASCII data (or EBCDIC on EBCDIC machines).  See L</"The UTF-8 flag">
+below.

 
 

-=item [$length =] from_to($string, FROM_ENCODING, TO_ENCODING [,CHECK])
+decode($valid_encoding, undef) is harmless but warns you for 
+C<Use of uninitialized value in subroutine entry>. 
+decode($valid_encoding, '') is harmless and warnless.

 
 

-Convert B<in-place> the data between two encodings.  How did the data
-in $string originally get to be in FROM_ENCODING?  Either using
-encode() or through PerlIO: See L</"Encoding and IO">.
-For encoding names and aliases, see L</"Defining Aliases">. 
-For CHECK see L</"Handling Malformed Data">.
+=item [$length =] from_to($octets, FROM_ENC, TO_ENC [, CHECK])

 
 

-For example to convert ISO-8859-1 data to UTF-8:
+Converts B<in-place> data between two encodings. The data in $octets
+must be encoded as octets and not as characters in Perl's internal
+format. For example, to convert ISO-8859-1 data to Microsoft's CP1250 encoding:

 
 

-       from_to($data, "iso-8859-1", "utf-8");
+  from_to($octets, "iso-8859-1", "cp1250");

 
 and to convert it back:
 
 
 and to convert it back:
 

-       from_to($data, "utf-8", "iso-8859-1");
+  from_to($octets, "cp1250", "iso-8859-1");

 
 Note that because the conversion happens in place, the data to be
 
 Note that because the conversion happens in place, the data to be

-converted cannot be a string constant, it must be a scalar variable.
+converted cannot be a string constant; it must be a scalar variable.

 
 

-from_to() return the length of the converted string on success, undef
+from_to() returns the length of the converted string in octets on success, undef

 otherwise.
 
 otherwise.
 

-=back
+B<CAVEAT>: The following operations look the same but are not quite so;

 
 

-=head2 UTF-8 / utf8
+  from_to($data, "iso-8859-1", "utf8"); #1
+  $data = decode("iso-8859-1", $data);  #2

 
 

-The Unicode consortium defines the UTF-8 standard as a way of encoding
-the entire Unicode repertoire as sequences of octets.  This encoding is
-expected to become very widespread. Perl can use this form internally
-to represent strings, so conversions to and from this form are
-particularly efficient (as octets in memory do not have to change,
-just the meta-data that tells Perl how to treat them).
+Both #1 and #2 make $data consist of a completely valid UTF-8 string
+but only #2 turns utf8 flag on.  #1 is equivalent to

 
 

-=over 4
+  $data = encode("utf8", decode("iso-8859-1", $data));
+
+See L</"The UTF-8 flag"> below.

 
 =item $octets = encode_utf8($string);
 
 
 =item $octets = encode_utf8($string);
 

-The characters that comprise string are encoded in Perl's superset of UTF-8
-and the resulting octets returned as a sequence of bytes. All possible
+Equivalent to C<$octets = encode("utf8", $string);> The characters
+that comprise $string are encoded in Perl's internal format and the
+result is returned as a sequence of octets. All possible

 characters have a UTF-8 representation so this function cannot fail.
 
 characters have a UTF-8 representation so this function cannot fail.
 

+

 =item $string = decode_utf8($octets [, CHECK]);
 
 =item $string = decode_utf8($octets [, CHECK]);
 

-The sequence of octets represented by $octets is decoded from UTF-8
-into a sequence of logical characters. Not all sequences of octets
-form valid UTF-8 encodings, so it is possible for this call to fail.
-For CHECK see L</"Handling Malformed Data">.
+equivalent to C<$string = decode("utf8", $octets [, CHECK])>.
+The sequence of octets represented by
+$octets is decoded from UTF-8 into a sequence of logical
+characters. Not all sequences of octets form valid UTF-8 encodings, so
+it is possible for this call to fail.  For CHECK, see
+L</"Handling Malformed Data">.

 
 =back
 
 
 =back
 


@@ -420,7 +447,7 @@ ones that are not loaded yet, say
 
   @all_encodings = Encode->encodings(":all");
 
 
   @all_encodings = Encode->encodings(":all");
 

-Or you can give the name of specific module.
+Or you can give the name of a specific module.

 
   @with_jp = Encode->encodings("Encode::JP");
 
 
   @with_jp = Encode->encodings("Encode::JP");
 


@@ -428,12 +455,12 @@ When "::" is not in the name, "Encode::" is assumed.
 
   @ebcdic = Encode->encodings("EBCDIC");
 
 
   @ebcdic = Encode->encodings("EBCDIC");
 

-To find which encodings are supported by this package in details, 
+To find out in detail which encodings are supported by this package,

 see L<Encode::Supported>.
 
 =head2 Defining Aliases
 
 see L<Encode::Supported>.
 
 =head2 Defining Aliases
 

-To add new alias to a given encoding,  Use;
+To add a new alias to a given encoding, use:

 
   use Encode;
   use Encode::Alias;
 
   use Encode;
   use Encode::Alias;


@@ -443,127 +470,252 @@ After that, newName can be used as an alias for ENCODING.
 ENCODING may be either the name of an encoding or an
 I<encoding object>
 
 ENCODING may be either the name of an encoding or an
 I<encoding object>
 

-See L<Encode::Alias> on details.
+But before you do so, make sure the alias is nonexistent with
+C<resolve_alias()>, which returns the canonical name thereof.
+i.e.

 
 

-=head1 Encoding and IO
+  Encode::resolve_alias("latin1") eq "iso-8859-1" # true
+  Encode::resolve_alias("iso-8859-12")   # false; nonexistent
+  Encode::resolve_alias($name) eq $name  # true if $name is canonical

 
 

-It is very common to want to do encoding transformations when
-reading or writing files, network connections, pipes etc.
-If Perl is configured to use the new 'perlio' IO system then
-C<Encode> provides a "layer" (See L<perliol>) which can transform
-data as it is read or written.
+resolve_alias() does not need C<use Encode::Alias>; it can be
+exported via C<use Encode qw(resolve_alias)>.

 
 

-Here is how the blind poet would modernise the encoding:
+See L<Encode::Alias> for details.

 
 

-    use Encode;
-    open(my $iliad,'<:encoding(iso-8859-7)','iliad.greek');
-    open(my $utf8,'>:utf8','iliad.utf8');
-    my @epic = <$iliad>;
-    print $utf8 @epic;
-    close($utf8);
-    close($illiad);
+=head1 Encoding via PerlIO

 
 

-In addition the new IO system can also be configured to read/write
-UTF-8 encoded characters (as noted above this is efficient):
+If your perl supports I<PerlIO> (which is the default), you can use a PerlIO layer to decode
+and encode directly via a filehandle.  The following two examples
+are totally identical in their functionality.

 
 

-    open(my $fh,'>:utf8','anything');
-    print $fh "Any \x{0021} string \N{SMILEY FACE}\n";
+  # via PerlIO
+  open my $in,  "<:encoding(shiftjis)", $infile  or die;
+  open my $out, ">:encoding(euc-jp)",   $outfile or die;
+  while(<$in>){ print $out $_; }

 
 

-Either of the above forms of "layer" specifications can be made the default
-for a lexical scope with the C<use open ...> pragma. See L<open>.
+  # via from_to
+  open my $in,  "<", $infile  or die;
+  open my $out, ">", $outfile or die;
+  while(<$in>){
+    from_to($_, "shiftjis", "euc-jp", 1);
+    print $out $_;
+  }

 
 

-Once a handle is open is layers can be altered using C<binmode>.
+Unfortunately, it may be that encodings are PerlIO-savvy.  You can check
+if your encoding is supported by PerlIO by calling the C<perlio_ok>
+method.

 
 

-Without any such configuration, or if Perl itself is built using
-system's own IO, then write operations assume that file handle accepts
-only I<bytes> and will C<die> if a character larger than 255 is
-written to the handle. When reading, each octet from the handle
-becomes a byte-in-a-character. Note that this default is the same
-behaviour as bytes-only languages (including Perl before v5.6) would
-have, and is sufficient to handle native 8-bit encodings
-e.g. iso-8859-1, EBCDIC etc. and any legacy mechanisms for handling
-other encodings and binary data.
+  Encode::perlio_ok("hz");             # False
+  find_encoding("euc-cn")->perlio_ok;  # True where PerlIO is available

 
 

-In other cases it is the programs responsibility to transform
-characters into bytes using the API above before doing writes, and to
-transform the bytes read from a handle into characters before doing
-"character operations" (e.g. C<lc>, C</\W+/>, ...).
+  use Encode qw(perlio_ok);            # exported upon request
+  perlio_ok("euc-jp")

 
 

-You can also use PerlIO to convert larger amounts of data you don't
-want to bring into memory.  For example to convert between ISO-8859-1
-(Latin 1) and UTF-8 (or UTF-EBCDIC in EBCDIC machines):
+Fortunately, all encodings that come with Encode core are PerlIO-savvy
+except for hz and ISO-2022-kr.  For gory details, see L<Encode::Encoding> and L<Encode::PerlIO>.

 
 

-    open(F, "<:encoding(iso-8859-1)", "data.txt") or die $!;
-    open(G, ">:utf8",                 "data.utf") or die $!;
-    while (<F>) { print G }
+=head1 Handling Malformed Data

 
 

-    # Could also do "print G <F>" but that would pull
-    # the whole file into memory just to write it out again.
+=over 2

 
 

-More examples:
+The I<CHECK> argument is used as follows.  When you omit it,
+the behaviour is the same as if you had passed a value of 0 for
+I<CHECK>.

 
 

-    open(my $f, "<:encoding(cp1252)")
-    open(my $g, ">:encoding(iso-8859-2)")
-    open(my $h, ">:encoding(latin9)")       # iso-8859-15
+=item I<CHECK> = Encode::FB_DEFAULT ( == 0)

 
 

-See L<PerlIO> for more information.
+If I<CHECK> is 0, (en|de)code will put a I<substitution character>
+in place of a malformed character.  For UCM-based encodings,
+E<lt>subcharE<gt> will be used.  For Unicode, the code point C<0xFFFD> is used.
+If the data is supposed to be UTF-8, an optional lexical warning
+(category utf8) is given.

 
 

-See also L<encoding> for how to change the default encoding of the
-data in your script.
+=item I<CHECK> = Encode::FB_CROAK ( == 1)

 
 

-=head1 Handling Malformed Data
+If I<CHECK> is 1, methods will die on error immediately with an error
+message.  Therefore, when I<CHECK> is set to 1,  you should trap the
+fatal error with eval{} unless you really want to let it die on error.
+
+=item I<CHECK> = Encode::FB_QUIET

 
 

-If I<CHECK> is not set, (en|de)code will put I<substitution character> in
-place of the malformed character.  for UCM-based encodings,
-E<lt>subcharE<gt> will be used.  For Unicode, \xFFFD is used.  If the
-data is supposed to be UTF-8, an optional lexical warning (category
-utf8) is given. 
+If I<CHECK> is set to Encode::FB_QUIET, (en|de)code will immediately
+return the portion of the data that has been processed so far when
+an error occurs. The data argument will be overwritten with
+everything after that point (that is, the unprocessed part of data).
+This is handy when you have to call decode repeatedly in the case
+where your source data may contain partial multi-byte character
+sequences, for example because you are reading with a fixed-width
+buffer. Here is some sample code that does exactly this:

 
 

-If I<CHECK> is true but not a code reference, dies with an error message.
+  my $data = ''; my $utf8 = '';
+  while(defined(read $fh, $buffer, 256)){
+    # buffer may end in a partial character so we append
+    $data .= $buffer;
+    $utf8 .= decode($encoding, $data, ENCODE::FB_QUIET);
+    # $data now contains the unprocessed partial character
+  }

 
 

-In future you will be able to use a code reference to a callback
+=item I<CHECK> = Encode::FB_WARN
+
+This is the same as above, except that it warns on error.  Handy when
+you are debugging the mode above.
+
+=item perlqq mode (I<CHECK> = Encode::FB_PERLQQ)
+
+=item HTML charref mode (I<CHECK> = Encode::FB_HTMLCREF)
+
+=item XML charref mode (I<CHECK> = Encode::FB_XMLCREF)
+
+For encodings that are implemented by Encode::XS, CHECK ==
+Encode::FB_PERLQQ turns (en|de)code into C<perlqq> fallback mode.
+
+When you decode, C<\xI<HH>> will be inserted for a malformed character,
+where I<HH> is the hex representation of the octet  that could not be
+decoded to utf8.  And when you encode, C<\x{I<HHHH>}> will be inserted,
+where I<HHHH> is the Unicode ID of the character that cannot be found
+in the character repertoire of the encoding.
+
+HTML/XML character reference modes are about the same, in place of
+C<\x{I<HHHH>}>, HTML uses C<&#I<NNNN>>; where I<NNNN> is a decimal digit and
+XML uses C<&#xI<HHHH>>; where I<HHHH> is the hexadecimal digit.
+
+=item The bitmask
+
+These modes are actually set via a bitmask.  Here is how the FB_XX
+constants are laid out.  You can import the FB_XX constants via
+C<use Encode qw(:fallbacks)>; you can import the generic bitmask
+constants via C<use Encode qw(:fallback_all)>.
+
+                     FB_DEFAULT FB_CROAK FB_QUIET FB_WARN  FB_PERLQQ
+ DIE_ON_ERR    0x0001             X
+ WARN_ON_ERR   0x0002                               X
+ RETURN_ON_ERR 0x0004                      X        X
+ LEAVE_SRC     0x0008
+ PERLQQ        0x0100                                        X
+ HTMLCREF      0x0200
+ XMLCREF       0x0400
+
+=head2 Unimplemented fallback schemes
+
+In the future, you will be able to use a code reference to a callback

 function for the value of I<CHECK> but its API is still undecided.
 
 function for the value of I<CHECK> but its API is still undecided.
 

+The fallback scheme does not work on EBCDIC platforms.
+

 =head1 Defining Encodings
 
 To define a new encoding, use:
 
 =head1 Defining Encodings
 
 To define a new encoding, use:
 

-    use Encode qw(define_alias);
+    use Encode qw(define_encoding);

     define_encoding($object, 'canonicalName' [, alias...]);
 
 I<canonicalName> will be associated with I<$object>.  The object
     define_encoding($object, 'canonicalName' [, alias...]);
 
 I<canonicalName> will be associated with I<$object>.  The object

-should provide the interface described in L<Encode::Encoding>
+should provide the interface described in L<Encode::Encoding>.

 If more than two arguments are provided then additional
 If more than two arguments are provided then additional

-arguments are taken as aliases for I<$object> as for C<define_alias>.
+arguments are taken as aliases for I<$object>.

 
 See L<Encode::Encoding> for more details.
 
 
 See L<Encode::Encoding> for more details.
 

-=head1 Messing with Perl's Internals
+=head1 The UTF-8 flag
+
+Before the introduction of utf8 support in perl, The C<eq> operator
+just compared the strings represented by two scalars. Beginning with
+perl 5.8, C<eq> compares two strings with simultaneous consideration
+of I<the utf8 flag>. To explain why we made it so, I will quote page
+402 of C<Programming Perl, 3rd ed.>
+
+=over 2
+
+=item Goal #1:
+
+Old byte-oriented programs should not spontaneously break on the old
+byte-oriented data they used to work on.
+
+=item Goal #2:
+
+Old byte-oriented programs should magically start working on the new
+character-oriented data when appropriate.
+
+=item Goal #3:
+
+Programs should run just as fast in the new character-oriented mode
+as in the old byte-oriented mode.
+
+=item Goal #4:
+
+Perl should remain one language, rather than forking into a
+byte-oriented Perl and a character-oriented Perl.
+
+=back
+
+Back when C<Programming Perl, 3rd ed.> was written, not even Perl 5.6.0
+was born and many features documented in the book remained
+unimplemented for a long time.  Perl 5.8 corrected this and the introduction
+of the UTF-8 flag is one of them.  You can think of this perl notion as of a
+byte-oriented mode (utf8 flag off) and a character-oriented mode (utf8
+flag on).
+
+Here is how Encode takes care of the utf8 flag.
+
+=over 2
+
+=item *
+
+When you encode, the resulting utf8 flag is always off.
+
+=item
+
+When you decode, the resulting utf8 flag is on unless you can
+unambiguously represent data.  Here is the definition of
+dis-ambiguity.
+
+After C<$utf8 = decode('foo', $octet);>,
+
+  When $octet is...   The utf8 flag in $utf8 is
+  ---------------------------------------------
+  In ASCII only (or EBCDIC only)            OFF
+  In ISO-8859-1                              ON
+  In any other Encoding                      ON
+  ---------------------------------------------
+
+As you see, there is one exception, In ASCII.  That way you can assue
+Goal #1.  And with Encode Goal #2 is assumed but you still have to be
+careful in such cases mentioned in B<CAVEAT> paragraphs.
+
+This utf8 flag is not visible in perl scripts, exactly for the same
+reason you cannot (or you I<don't have to>) see if a scalar contains a
+string, integer, or floating point number.   But you can still peek
+and poke these if you will.  See the section below.
+
+=back
+
+=head2 Messing with Perl's Internals

 
 The following API uses parts of Perl's internals in the current
 
 The following API uses parts of Perl's internals in the current

-implementation.  As such they are efficient, but may change.
+implementation.  As such, they are efficient but may change.

 
 

-=over 4
+=over 2

 
 =item is_utf8(STRING [, CHECK])
 
 
 =item is_utf8(STRING [, CHECK])
 

-[INTERNAL] Test whether the UTF-8 flag is turned on in the STRING.
+[INTERNAL] Tests whether the UTF-8 flag is turned on in the STRING.

 If CHECK is true, also checks the data in STRING for being well-formed
 UTF-8.  Returns true if successful, false otherwise.
 
 =item _utf8_on(STRING)
 
 If CHECK is true, also checks the data in STRING for being well-formed
 UTF-8.  Returns true if successful, false otherwise.
 
 =item _utf8_on(STRING)
 

-[INTERNAL] Turn on the UTF-8 flag in STRING.  The data in STRING is
+[INTERNAL] Turns on the UTF-8 flag in STRING.  The data in STRING is

 B<not> checked for being well-formed UTF-8.  Do not use unless you
 B<know> that the STRING is well-formed UTF-8.  Returns the previous
 B<not> checked for being well-formed UTF-8.  Do not use unless you
 B<know> that the STRING is well-formed UTF-8.  Returns the previous

-state of the UTF-8 flag (so please don't test the return value as
-I<not> success or failure), or C<undef> if STRING is not a string.
+state of the UTF-8 flag (so please don't treat the return value as
+indicating success or failure), or C<undef> if STRING is not a string.

 
 =item _utf8_off(STRING)
 
 
 =item _utf8_off(STRING)
 

-[INTERNAL] Turn off the UTF-8 flag in STRING.  Do not use frivolously.
-Returns the previous state of the UTF-8 flag (so please don't test the
-return value as I<not> success or failure), or C<undef> if STRING is
+[INTERNAL] Turns off the UTF-8 flag in STRING.  Do not use frivolously.
+Returns the previous state of the UTF-8 flag (so please don't treat the
+return value as indicating success or failure), or C<undef> if STRING is

 not a string.
 
 =back
 not a string.
 
 =back


@@ -572,12 +724,19 @@ not a string.
 
 L<Encode::Encoding>,
 L<Encode::Supported>,
 
 L<Encode::Encoding>,
 L<Encode::Supported>,

-L<PerlIO>, 
+L<Encode::PerlIO>,

 L<encoding>,
 L<encoding>,

-L<perlebcdic>, 
-L<perlfunc/open>, 
-L<perlunicode>, 
-L<utf8>, 
+L<perlebcdic>,
+L<perlfunc/open>,
+L<perlunicode>,
+L<utf8>,

 the Perl Unicode Mailing List E<lt>perl-unicode@perl.orgE<gt>
 
 the Perl Unicode Mailing List E<lt>perl-unicode@perl.orgE<gt>
 

+=head1 MAINTAINER
+
+This project was originated by Nick Ing-Simmons and later maintained
+by Dan Kogai E<lt>dankogai@dan.co.jpE<gt>.  See AUTHORS for a full
+list of people involved.  For any questions, use
+E<lt>perl-unicode@perl.orgE<gt> so we can all share.
+

 =cut
 =cut