=head1 NAME

ExtUtils::Typemaps - Read/Write/Modify Perl/XS typemap files

=head1 SYNOPSIS

  # read/create file
  my $typemap = ExtUtils::Typemaps->new(file => 'typemap');
  # alternatively create an in-memory typemap
  # $typemap = ExtUtils::Typemaps->new();
  # alternatively create an in-memory typemap by parsing a string
  # $typemap = ExtUtils::Typemaps->new(string => $sometypemap);
  
  # add a mapping
  $typemap->add_typemap(ctype => 'NV', xstype => 'T_NV');
  $typemap->add_inputmap(
     xstype => 'T_NV', code => '$var = ($type)SvNV($arg);'
  );
  $typemap->add_outputmap(
     xstype => 'T_NV', code => 'sv_setnv($arg, (NV)$var);'
  );
  $typemap->add_string(string => $typemapstring);
                                           # will be parsed and merged
  
  # remove a mapping (same for remove_typemap and remove_outputmap...)
  $typemap->remove_inputmap(xstype => 'SomeType');
  
  # save a typemap to a file
  $typemap->write(file => 'anotherfile.map');
  
  # merge the other typemap into this one
  $typemap->merge(typemap => $another_typemap);

=head1 DESCRIPTION

This module can read, modify, create and write Perl XS typemap files. If you don't know
what a typemap is, please confer the L<perlxstut> and L<perlxs> manuals.

The module is not entirely round-trip safe: For example it currently simply strips all comments.
The order of entries in the maps is, however, preserved.

We check for duplicate entries in the typemap, but do not check for missing
C<TYPEMAP> entries for C<INPUTMAP> or C<OUTPUTMAP> entries since these might be hidden
in a different typemap.

=head1 METHODS


=cut

=head2 new

Returns a new typemap object. Takes an optional C<file> parameter.
If set, the given file will be read. If the file doesn't exist, an empty typemap
is returned.

Alternatively, if the C<string> parameter is given, the supplied
string will be parsed instead of a file.


=cut

=head2 file

Get/set the file that the typemap is written to when the
C<write> method is called.


=cut

=head2 add_typemap

Add a C<TYPEMAP> entry to the typemap.

Required named arguments: The C<ctype> (e.g. C<ctype =E<gt> 'double'>)
and the C<xstype> (e.g. C<xstype =E<gt> 'T_NV'>).

Optional named arguments: C<replace =E<gt> 1> forces removal/replacement of
existing C<TYPEMAP> entries of the same C<ctype>. C<skip =E<gt> 1>
triggers a I<"first come first serve"> logic by which new entries that conflict
with existing entries are silently ignored.

As an alternative to the named parameters usage, you may pass in
an C<ExtUtils::Typemaps::Type> object as first argument, a copy of which will be
added to the typemap. In that case, only the C<replace> or C<skip> named parameters
may be used after the object. Example:

  $map->add_typemap($type_obj, replace => 1);


=cut

=head2 add_inputmap

Add an C<INPUT> entry to the typemap.

Required named arguments:
The C<xstype> (e.g. C<xstype =E<gt> 'T_NV'>)
and the C<code> to associate with it for input.

Optional named arguments: C<replace =E<gt> 1> forces removal/replacement of
existing C<INPUT> entries of the same C<xstype>. C<skip =E<gt> 1>
triggers a I<"first come first serve"> logic by which new entries that conflict
with existing entries are silently ignored.

As an alternative to the named parameters usage, you may pass in
an C<ExtUtils::Typemaps::InputMap> object as first argument, a copy of which will be
added to the typemap. In that case, only the C<replace> or C<skip> named parameters
may be used after the object. Example:

  $map->add_inputmap($type_obj, replace => 1);


=cut

=head2 add_outputmap

Add an C<OUTPUT> entry to the typemap.
Works exactly the same as C<add_inputmap>.


=cut

=head2 add_string

Parses a string as a typemap and merge it into the typemap object.

Required named argument: C<string> to specify the string to parse.


=cut

=head2 remove_typemap

Removes a C<TYPEMAP> entry from the typemap.

Required named argument: C<ctype> to specify the entry to remove from the typemap.

Alternatively, you may pass a single C<ExtUtils::Typemaps::Type> object.


=cut

=head2 remove_inputmap

Removes an C<INPUT> entry from the typemap.

Required named argument: C<xstype> to specify the entry to remove from the typemap.

Alternatively, you may pass a single C<ExtUtils::Typemaps::InputMap> object.


=cut

=head2 remove_inputmap

Removes an C<OUTPUT> entry from the typemap.

Required named argument: C<xstype> to specify the entry to remove from the typemap.

Alternatively, you may pass a single C<ExtUtils::Typemaps::OutputMap> object.


=cut

=head2 get_typemap

Fetches an entry of the TYPEMAP section of the typemap.

Mandatory named arguments: The C<ctype> of the entry.

Returns the C<ExtUtils::Typemaps::Type>
object for the entry if found.


=cut

=head2 get_inputmap

Fetches an entry of the INPUT section of the
typemap.

Mandatory named arguments: The C<xstype> of the
entry or the C<ctype> of the typemap that can be used to find
the C<xstype>. To wit, the following pieces of code
are equivalent:

  my $type = $typemap->get_typemap(ctype => $ctype)
  my $input_map = $typemap->get_inputmap(xstype => $type->xstype);

  my $input_map = $typemap->get_inputmap(ctype => $ctype);

Returns the C<ExtUtils::Typemaps::InputMap>
object for the entry if found.


=cut

=head2 get_outputmap

Fetches an entry of the OUTPUT section of the
typemap.

Mandatory named arguments: The C<xstype> of the
entry or the C<ctype> of the typemap that can be used to
resolve the C<xstype>. (See above for an example.)

Returns the C<ExtUtils::Typemaps::InputMap>
object for the entry if found.


=cut

=head2 write

Write the typemap to a file. Optionally takes a C<file> argument. If given, the
typemap will be written to the specified file. If not, the typemap is written
to the currently stored file name (see C<-E<gt>file> above, this defaults to the file
it was read from if any).


=cut

=head2 as_string

Generates and returns the string form of the typemap.


=cut

=head2 as_embedded_typemap

Generates and returns the string form of the typemap with the
appropriate prefix around it for verbatim inclusion into an
XS file as an embedded typemap. This will return a string like

  TYPEMAP: <<END_OF_TYPEMAP
  ... typemap here (see as_string) ...
  END_OF_TYPEMAP

The method takes care not to use a HERE-doc end marker that
appears in the typemap string itself.


=cut

=head2 merge

Merges a given typemap into the object. Note that a failed merge
operation leaves the object in an inconsistent state so clone it if necessary.

Mandatory named arguments: Either C<typemap =E<gt> $another_typemap_obj>
or C<file =E<gt> $path_to_typemap_file> but not both.

Optional arguments: C<replace =E<gt> 1> to force replacement
of existing typemap entries without warning or C<skip =E<gt> 1>
to skip entries that exist already in the typemap.


=cut

=head2 is_empty

Returns a bool indicating whether this typemap is entirely empty.


=cut

=head2 list_mapped_ctypes

Returns a list of the C types that are mappable by
this typemap object.


=cut

=head2 _get_typemap_hash

Returns a hash mapping the C types to the XS types:

  {
    'char **' => 'T_PACKEDARRAY',
    'bool_t' => 'T_IV',
    'AV *' => 'T_AVREF',
    'InputStream' => 'T_IN',
    'double' => 'T_DOUBLE',
    # ...
  }

This is documented because it is used by C<ExtUtils::ParseXS>,
but it's not intended for general consumption. May be removed
at any time.


=cut

=head2 _get_inputmap_hash

Returns a hash mapping the XS types (identifiers) to the
corresponding INPUT code:

  {
    'T_CALLBACK' => '   $var = make_perl_cb_$type($arg)
  ',
    'T_OUT' => '    $var = IoOFP(sv_2io($arg))
  ',
    'T_REF_IV_PTR' => '   if (sv_isa($arg, \\"${ntype}\\")) {
    # ...
  }

This is documented because it is used by C<ExtUtils::ParseXS>,
but it's not intended for general consumption. May be removed
at any time.


=cut

=head2 _get_outputmap_hash

Returns a hash mapping the XS types (identifiers) to the
corresponding OUTPUT code:

  {
    'T_CALLBACK' => '   sv_setpvn($arg, $var.context.value().chp(),
                $var.context.value().size());
  ',
    'T_OUT' => '    {
            GV *gv = newGVgen("$Package");
            if ( do_open(gv, "+>&", 3, FALSE, 0, 0, $var) )
                sv_setsv(
                  $arg,
                  sv_bless(newRV((SV*)gv), gv_stashpv("$Package",1))
                );
            else
                $arg = &PL_sv_undef;
         }
  ',
    # ...
  }

This is documented because it is used by C<ExtUtils::ParseXS>,
but it's not intended for general consumption. May be removed
at any time.


=cut

=head2 _get_prototype_hash

Returns a hash mapping the C types of the typemap to their
corresponding prototypes.

  {
    'char **' => '$',
    'bool_t' => '$',
    'AV *' => '$',
    'InputStream' => '$',
    'double' => '$',
    # ...
  }

This is documented because it is used by C<ExtUtils::ParseXS>,
but it's not intended for general consumption. May be removed
at any time.


=cut

=head1 CAVEATS

Inherits some evil code from C<ExtUtils::ParseXS>.

=head1 SEE ALSO

The parser is heavily inspired from the one in L<ExtUtils::ParseXS>.

For details on typemaps: L<perlxstut>, L<perlxs>.

=head1 AUTHOR

Steffen Mueller C<<smueller@cpan.org>>

=head1 COPYRIGHT & LICENSE

Copyright 2009, 2010, 2011, 2012 Steffen Mueller

This program is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.


=cut