gistfile1.txt

VALUE  rb_index                             =  Qnil;
VALUE  rb_key                               =  Qnil;
VALUE  rb_hash_descriptor_index_key         =  Qnil;
VALUE  rb_hash_descriptor_index_keys_array  =  Qnil;
VALUE  rb_args_array                        =  Qnil;

RARG_Define(

  /*----------------------------------------------*/

  //  { :index  => [ <key> ] }
  //  { "index" => [ <key> ] }
  //  { :index  => <key> }
  //  { "index" => <key> }
  R_Descriptor(  R_Parameter(  R_Hash(    R_Key(    R_Type(        R_SYMBOL | R_STRING ) ),
                                          R_Data(   R_MatchArray(  rb_hash_descriptor_index_keys_array ) ),
                                                    R_MatchAny(    rb_hash_descriptor_index_key ) ) ) ) ),


  /*----------------------------------------------*/

  //  :index, <key>
  //  "index", <key>
  R_Descriptor(  R_Parameter(  R_MatchType(  R_SYMBOL | R_STRING,    
                                             rb_index ) ),
                 R_Parameter(  R_MatchAny(   rb_key ) ) ),

  /*----------------------------------------------*/

  //  [ <arg> ]
  R_Descriptor(  R_Parameter(  R_MatchArray(  rb_args_array ) ) ),

  /*----------------------------------------------*/

  //  <key>
  R_Descriptor(  R_Parameter(  R_MatchAny(    rb_key ) ) )

  /*----------------------------------------------*/
  
)

RARG_Parse( argc, args );

if (   rb_index != Qnil
   &&  rb_key != Qnil )  {

  // parse index/key pair normally

}
else if (   rb_hash_descriptor_index_key != Qnil
        ||  rb_hash_descriptor_index_keys_array != Qnil )  {

  // { :index => key } or { :index => [ keys ] }
  // iterate and pass :index pairs/sets individually to this function to be parsed

}
else if ( rb_args_array != Qnil )  {

  // [ args ]
  // pass each to this function to be parsed

}