Add the Encode extension. The code is still largely just skeleton.

[p5sagit/p5-mst-13.2.git] / ext / Encode / Encode.pm

package Encode;

$VERSION = 0.01;

require DynaLoader;
require Exporter;

@ISA = qw(Exporter DynaLoader);

@EXPORT_OK =
    qw(
       bytes_to_utf8
       utf8_to_bytes
       chars_to_utf8
       utf8_to_chars
       utf8_to_chars_check
       bytes_to_chars
       chars_to_bytes
       from_to
       is_utf8
       on_utf8
       off_utf8
       utf_to_utf
      );

bootstrap Encode ();

=pod

=head1 NAME

Encode - character encodings

=head2 TERMINOLOGY

=over

=item *

I<char>: a character in the range 0..maxint (at least 2**32-1)

=item *

I<byte>: a character in the range 0..255

=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.

=head2 bytes

=over 4

=item *

        bytes_to_utf8(STRING [, FROM])

The bytes in STRING are recoded in-place into UTF-8.  If no FROM is
specified the bytes are expected to be encoded in US-ASCII or ISO
8859-1 (Latin 1).  Returns the new size of STRING, or C<undef> if
there's a failure.

[INTERNAL] Also the UTF-8 flag of STRING is turned on.        

=item *

        utf8_to_bytes(STRING [, TO [, CHECK]])

The UTF-8 in STRING is decoded in-place into bytes.  If no TO encoding
is specified the bytes are expected to be encoded in US-ASCII or ISO
8859-1 (Latin 1).  Returns the new size of STRING, or C<undef> if
there's a failure.

What if there are characters > 255?  What if the UTF-8 in STRING is
malformed?  See L</"Handling Malformed Data">.

[INTERNAL] The UTF-8 flag of STRING is not checked.

=back

=head2 chars

=over 4

=item *

        chars_to_utf8(STRING)

The chars in STRING are encoded in-place into UTF-8.  Returns the new
size of STRING, or C<undef> if there's a failure.

No assumptions are made on the encoding of the chars.  If you want to
assume that the chars are Unicode and to trap illegal Unicode
characters, you must use C<from_to('Unicode', ...)>.

[INTERNAL] Also the UTF-8 flag of STRING is turned on.

=over 4

=item *

        utf8_to_chars(STRING)

The UTF-8 in STRING is decoded in-place into chars.  Returns the new
size of STRING, or C<undef> if there's a failure. 

If the UTF-8 in STRING is malformed C<undef> is returned, and also an
optional lexical warning (category utf8) is given.

[INTERNAL] The UTF-8 flag of STRING is not checked.

=item *

        utf8_to_chars_check(STRING [, CHECK])

(Note that special naming of this interface since a two-argument
utf8_to_chars() has different semantics.)

The UTF-8 in STRING is decoded in-place into chars.  Returns the new
size of STRING, or C<undef> if there is a failure.

If the UTF-8 in STRING is malformed?  See L</"Handling Malformed Data">.

[INTERNAL] The UTF-8 flag of STRING is not checked.

=back

=head2 chars With Encoding

=over 4

=item *

        chars_to_utf8(STRING, FROM [, CHECK])

The chars in STRING encoded in FROM are recoded in-place into UTF-8.
Returns the new size of STRING, or C<undef> if there's a failure.

No assumptions are made on the encoding of the chars.  If you want to
assume that the chars are Unicode and to trap illegal Unicode
characters, you must use C<from_to('Unicode', ...)>.

[INTERNAL] Also the UTF-8 flag of STRING is turned on.

=item *

        utf8_to_chars(STRING, TO [, CHECK])

The UTF-8 in STRING is decoded in-place into chars encoded in TO.
Returns the new size of STRING, or C<undef> if there's a failure.

If the UTF-8 in STRING is malformed?  See L</"Handling Malformed Data">.

[INTERNAL] The UTF-8 flag of STRING is not checked.

=item *

	bytes_to_chars(STRING, FROM [, CHECK])

The bytes in STRING encoded in FROM are recoded in-place into chars.
Returns the new size of STRING in bytes, or C<undef> if there's a
failure.

If the mapping is impossible?  See L</"Handling Malformed Data">.

=item *

	chars_to_bytes(STRING, TO [, CHECK])

The chars in STRING are recoded in-place to bytes encoded in TO.
Returns the new size of STRING in bytes, or C<undef> if there's a
failure.

If the mapping is impossible?  See L</"Handling Malformed Data">.

=item *

        from_to(STRING, FROM, TO [, CHECK])

The chars in STRING encoded in FROM are recoded in-place into TO.
Returns the new size of STRING, or C<undef> if there's a failure.

If mapping between the encodings is impossible?
See L</"Handling Malformed Data">.

[INTERNAL] If TO is UTF-8, also the UTF-8 flag of STRING is turned on.

=back

=head2 Testing For UTF-8

=over 4

=item *

        is_utf8(STRING [, CHECK])

[INTERNAL] Test 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.

=back

=head2 Toggling UTF-8-ness

=over 4

=item *

        on_utf8(STRING)

[INTERNAL] Turn 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
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.

=item *

        off_utf8(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
not a string.

=back

=head2 UTF-16 and UTF-32 Encodings

=over 4

=item *

        utf_to_utf(STRING, FROM, TO [, CHECK])

The data in STRING is converted from Unicode Transfer Encoding FROM to
Unicode Transfer Encoding TO.  Both FROM and TO may be any of the
following tags (case-insensitive, with or without 'utf' or 'utf-' prefix):

        tag             meaning

        '7'             UTF-7
        '8'             UTF-8
        '16be'          UTF-16 big-endian
        '16le'          UTF-16 little-endian
        '16'            UTF-16 native-endian
        '32be'          UTF-32 big-endian
        '32le'          UTF-32 little-endian
        '32'            UTF-32 native-endian

UTF-16 is also known as UCS-2, 16 bit or 2-byte chunks, and UTF-32 as
UCS-4, 32-bit or 4-byte chunks.  Returns the new size of STRING, or
C<undef> is there's a failure.

If FROM is UTF-8 and the UTF-8 in STRING is malformed?  See
L</"Handling Malformed Data">.

[INTERNAL] Even if CHECK is true and FROM is UTF-8, the UTF-8 flag of
STRING is not checked.  If TO is UTF-8, also the UTF-8 flag of STRING is
turned on.  Identical FROM and TO are fine.

=back

=head2 Handling Malformed Data

If CHECK is not set, C<undef> is returned.  If the data is supposed to
be UTF-8, an optional lexical warning (category utf8) is given.  If
CHECK is true but not a code reference, dies.  If CHECK is a code
reference, it is called with the arguments

	(MALFORMED_STRING, STRING_FROM_SO_FAR, STRING_TO_SO_FAR)

Two return values are expected from the call: the string to be used in
the result string in place of the malformed section, and the length of
the malformed section in bytes.

=cut

sub bytes_to_utf8 {
    &_bytes_to_utf8;
}

sub utf8_to_bytes {
    &_utf8_to_bytes;
}

sub chars_to_utf8 {
    &C_to_utf8;
}

sub utf8_to_chars {
    &_utf8_to_chars;
}

sub utf8_to_chars_check {
    &_utf8_to_chars_check;
}

sub bytes_to_chars {
    &_bytes_to_chars;
}

sub chars_to_bytes {
    &_chars_to_bytes;
}

sub from_to {
    &_from_to;
}

sub is_utf8 {
    &_is_utf8;
}

sub on_utf8 {
    &_on_utf8;
}

sub off_utf8 {
    &_off_utf8;
}

sub utf_to_utf {
    &_utf_to_utf;
}