XML::Doctype - A DTD object class

       Barrie Slaymaker <barries@slaysys.com>

       This module is Copyright 2000, 2005 Barrie Slaymaker.  All rights reserved.

       This module is licensed under your choice of the Artistic, BSD or General Public License.

perl v5.34.0                                       2022-06-28                                  XML::Doctype(3pm)

       This module parses DTDs and allows them to be saved as .pm files and reloaded.  The ability to save and
       reload is intended to aid in packaging parsed DTDs with XML tools so that XML::Parser need not be
       installed.

       new
              $doctype = XML::Doctype->new() ;
              $doctype = XML::Doctype->new( 'FooML', DTD_TEXT => $doctype_text ) ;
              $doctype = XML::Doctype->new( 'FooML', SYSTEM_ID => 'FooML.dtd' ) ;

       name
              $name = $doctype->name() ;

              Sets/gets the name.

       parse_dtd
              $doctype->parse_dtd( $name, $doctype_text ) ;
              $doctype->parse_dtd( $name, $doctype_text, 'internal' ) ;

           Parses  the text of a DTD from a scalar.  $name is used to indicate the name of the DOCTYPE, and thus
           the root node.

           The DTD is considered to be external unless the third parameter is TRUE.

       parse_dtd_file
              $doctype->parse_dtd_file( $name, $system_id [, $public_id] ) ;
              $doctype->parse_dtd_file( $name, $system_id [, $public_id], 'internal' ) ;

           Parses a DTD from a file.  Eventually will support full URL syntax.

           $public_id is ignored for now, and $system_id is used to locate the DTD.

           This routine requires XML::Parser.  XML::Parser is not loaded at any other time and is not needed  to
           use the resulting DTD object.

           The DTD is considered to be external unless the fourth parameter is TRUE.

              $doctype->parse_dtd_file( $name, $system_id, $p_id, 'internal' ) ;
              $doctype->parse_dtd_file( $name, $system_id, undef, 'internal' ) ;

       system_id
              $system_id = $doctype->system_id() ;

              Sets/gets the system ID.

       public_id
              $public_id = $doctype->public_id() ;

              Sets/gets the public_id.

       element_decl
              $elt_decl = $doctype->element_decl( $name ) ;

           Returns  the  XML::Doctype:Element  object associated with $name.  These can be defined by <!ELEMENT>
           tags or undefined, which can happen if they were just referred-to by <!ELEMENT> or <!ATTLIST> tags.

       element_names
           Returns an unsorted list of element names.  This list includes names that are declared and undeclared
           (but referred to in element declarations or attribute definitions).

       as_pm
              open( PM, "FooML/DTD/v1_001.pm" )            or die $! ;
              print PM $doctype->as_pm( 'FooML::DTD::v1_001' ) or die $! ;
              close PM                                     or die $! ;

           Then, later:

              use FooML::DTD::v1_001 ;   # Do *not* use () as a parameter list!

           Returns string containing the DTD as an independent module, allowing the DTD  to  be  parsed  in  the
           development  environment  and  shipped  as  Perl  code,  so that the target environment need not have
           XML::Parser installed.

           This is useful for XML creation-only tools and as  an  efficiency  tuning  measure  if  you  will  be
           rereading the same set of DTDs over and over again.

       import
       use
              use XML::Doctype NAME => 'FooML', SYSTEM_ID => 'dtds/FooML.dtd' ;

           import()  constructs  a  default  DTD  object  for  the  calling  package  so that XML::ValidWriter's
           functional interface can use it.

           If XML::Doctype is subclassed, the subclasses' constructor is called with all parameters.

       XML::Doctype - A DTD object class

       This module is alpha code.  It's developed enough to support XML::ValidWriter, but need a lot of work.
       Some big things that are lacking are:

       •   methods or objects to build / traverse the DTD

       •   XML::Doctype::ELEMENT

       •   XML::Doctype::ATTLIST

       •   XML::Doctype::ENITITY

       This object uses the fields pragma, so you should use base and fields for any subclasses.

          # To parse an external DTD at compile time, useful when
          # using XML::ValidWriter
          use XML::Doctype NAME => 'FooML', SYSTEM_ID => 'FooML.dtd' ;
          use XML::Doctype NAME => 'FooML', DTD_TEXT  => $dtd ;

          # Parsing at run-time
          $doctype = XML::Doctype->new( 'FooML', SYSTEM_ID => 'FooML.dtd' ) ;

          # or
          $doctype = XML::Doctype->new() ;
          $doctype->parse( 'FooML', 'FooML.dtd' ) ;

          # Saving the parsed object
          open( PM, ">FooML/DTD/v1_000.pm" ) or die $! ;
          print PM $doctype->as_pm( 'FooML::DTD::v1_000' ) ;

          # Using a saved parsed DTD
          use FooML::DTD::v1_000 ;

          $doctype = FooML::DTD::v1_000->new() ;