/// Decodes an XPath expression, further manipulating a token list
/// \n On input, we have a list of basic lexical tokens. We only merge here the 
/// multiple tokens : like '::' or '!='. We also delete whitespace tokens
void token_list::v_tokenize_expression ()
{
   v_set_current_top ();
   while (ltp_get (1))
   {
      switch (ltp_get (0) -> lex_get_value ())
      {
         case lex_colon :
            if (ltp_get (1) -> lex_get_value () == lex_colon)
            {
               v_replace_current (lex_2_colon, "::");
               v_delete_next ();
            }
            else
               v_inc_current (1);
            break;
         case lex_slash :
            if (ltp_get (1) -> lex_get_value () == lex_slash)
            {
               v_replace_current (lex_2_slash, "//");
               v_delete_next ();
            }
            else
               v_inc_current (1);
            break;
         case lex_exclam :
            if (ltp_get (1) -> lex_get_value () == lex_equal)
            {
               v_replace_current (lex_not_equal, "!=");
               v_delete_next ();
            }
            else
               v_inc_current (1);
            break;
         case lex_lt :
            if (ltp_get (1) -> lex_get_value () == lex_equal)
            {
               v_replace_current (lex_lt_equal, "<=");
               v_delete_next ();
            }
            else
               v_inc_current (1);
            break;
         case lex_gt :
            if (ltp_get (1) -> lex_get_value () == lex_equal)
            {
               v_replace_current (lex_gt_equal, ">=");
               v_delete_next ();
            }
            else
               v_inc_current (1);
            break;
         case lex_dot :
            if (ltp_get (1) -> lex_get_value () == lex_dot)
            {
               v_replace_current (lex_2_dot, "..");
               v_delete_next ();
            }
            else
               v_inc_current (1);
            break;
         case lex_space :
            v_delete_current ();
            break;
         default :
            v_inc_current (1);
            break;
      }     // switch
   }     // while
}
예제 #2
0
/// Recognize one XPath construction
/// \n This function throws exceptions every time there's a failure in a backtracking attempt.
/// This should only happen when o_final is false, otherwise we have a syntax error
bool token_syntax_decoder::o_recognize (
   xpath_construct xc_current,   ///< XPath construction to recognize
   bool o_final)                 ///< true if we need to go on, false if it's just a trial 
                                 /// in the backtracking
{
   lex_token * ltp_freeze;
   bool o_empty, o_found, o_location_path, o_qname, o_temp;
   unsigned u_nb_argument, u_nb_predicate;
   int i_action_counter;
   bool o_test_more;

   u_nb_recurs++;
   if (u_nb_recurs > 10000)
      throw syntax_overflow ();
   ltp_freeze = NULL;

   switch (xc_current)
   {
      case xpath_location_path :
         //
         // [1]   LocationPath			::=   RelativeLocationPath 
			// 					         | AbsoluteLocationPath 
         //
         if (! ltp_get (0))
            return false;
         switch (ltp_get (0) -> lex_get_value ())
         {
            case lex_slash :
            case lex_2_slash :
               if (! o_recognize (xpath_absolute_location_path, o_final))
                  return false;
               if (o_final)
                  v_action (xpath_location_path, xpath_location_path_abs);
               break;
            default :
               if (! o_recognize (xpath_relative_location_path, o_final))
                  return false;
               if (o_final)
                  v_action (xpath_location_path, xpath_location_path_rel);
               break;
         }
         break;         

      case xpath_absolute_location_path :
         // [2]   AbsoluteLocationPath	::=   '/' RelativeLocationPath? 
			// 					         | AbbreviatedAbsoluteLocationPath 
         if (! ltp_get (0))
            return false;
         i_action_counter = i_get_action_counter ();
         switch (ltp_get (0) -> lex_get_value ())
         {
            case lex_slash :
               v_inc_current (1);
               ltp_freeze = ltp_get (0);
               o_temp = o_recognize (xpath_relative_location_path, false);
               if (o_temp)
               {
                  v_set_current (ltp_freeze);
                  o_recognize (xpath_relative_location_path, o_final);
                  if (o_final)
                     v_action (xpath_absolute_location_path, xpath_absolute_location_path_slash_rel, i_action_counter);
               }
               else
               {
                  v_set_current (ltp_freeze);
                  if (o_final)
                     v_action (xpath_absolute_location_path, xpath_absolute_location_path_slash, i_action_counter);
               }
               break;
            case lex_2_slash :
               if (! o_recognize (xpath_abbreviated_absolute_location_path, o_final))
                  return false;
               if (o_final)
                  v_action (xpath_absolute_location_path, xpath_absolute_location_path_abbrev, i_action_counter);
               break;
            default :
               return false;
         }
         break;         

      case xpath_relative_location_path :
         //
         // [3]   RelativeLocationPath	::=   Step 
			// 					         | RelativeLocationPath '/' Step 
			// 					         | AbbreviatedRelativeLocationPath
         // [11]   AbbreviatedRelativeLocationPath	::=   RelativeLocationPath '//' Step 
         //
         i_action_counter = i_get_action_counter ();
         if (! o_recognize (xpath_step, o_final))
            return false;
         if (ltp_get (0) && ltp_get (0) -> lex_get_value () == lex_slash)
         {
            v_inc_current (1);
            if (! o_recognize (xpath_relative_location_path, o_final))
               return false;
            if (o_final)
               v_action (xpath_relative_location_path, xpath_relative_location_path_rel_step, i_action_counter);
         }
         else
            if (ltp_get (0) && ltp_get (0) -> lex_get_value () == lex_2_slash)
            {
               v_inc_current (1);
               if (! o_recognize (xpath_relative_location_path, o_final))
                  return false;
               if (o_final)
                  v_action (xpath_relative_location_path, xpath_relative_location_path_rel_double_slash_step, i_action_counter);
            }
            else
            {
               if (o_final)
                  v_action (xpath_relative_location_path, xpath_relative_location_path_step, i_action_counter);
            }
         break;         

      case xpath_step :
         // [4]   Step					::=   AxisSpecifier NodeTest Predicate* 
			// 					         | AbbreviatedStep 
         if (! ltp_get (0))
            return false;
         switch (ltp_get (0) -> lex_get_value ())
         {
            case lex_dot :
            case lex_2_dot :
               if (! o_recognize (xpath_abbrieviated_step, o_final))
                  return false;
               if (o_final)
                  v_action (xpath_step, xpath_step_abbrev);
               break;
            default :
               if (! o_recognize (xpath_axis_specifier, o_final))
                  return false;
               if (! o_recognize (xpath_node_test, o_final))
                  return false;
               o_found = true;
               u_nb_predicate = 0;
               while (o_found && ltp_get (0) && ltp_get (0) -> lex_get_value () == lex_obrack)
               {
                  ltp_freeze = ltp_get (0);
                  if (! o_recognize (xpath_predicate, false))
                     o_found = false;
                  else
                  {
                     v_set_current (ltp_freeze);
                     o_recognize (xpath_predicate, o_final);
                     u_nb_predicate++;
                  }
               }
               if (o_final)
                  v_action (xpath_step, xpath_step_full, u_nb_predicate);
               break;               
         }
         break;

      case xpath_axis_specifier :
         // 
         // [5]   AxisSpecifier			::=   AxisName '::' 
			// 					         | AbbreviatedAxisSpecifier 
         //
         // [13]   AbbreviatedAxisSpecifier			::=   '@'?
         o_empty = false;
         if (ltp_get (0))
         {
            switch (ltp_get (0) -> lex_get_value ())
            {
               case lex_at :
                  v_inc_current (1);
                  if (o_final)
                     v_action (xpath_axis_specifier, xpath_axis_specifier_at);
                  break;
               default :
                  if (o_is_axis_name (ltp_get (0) -> lex_get_value ()))
                  {
                     if (! o_recognize (xpath_axis_name, o_final))
                        return false;
                     if (! ltp_get (0))
                        return false;
                     if (ltp_get (0) -> lex_get_value () != lex_2_colon)
                        return false;
                     v_inc_current (1);
                     if (o_final)
                        v_action (xpath_axis_specifier, xpath_axis_specifier_axis_name);
                  }            
                  else
                     o_empty = true;
                  break;
            }
         }
         else
            o_empty = true;
         if (o_empty)
         {
            if (o_final)
            {
               v_action (xpath_abbreviated_axis_specifier, 1);
               v_action (xpath_axis_specifier, xpath_axis_specifier_empty);
            }
         }            
         break;

      case xpath_axis_name :
         // [6]   AxisName				::=   'ancestor' 
         // 								| 'ancestor-or-self' 
         // 								| 'attribute' 
         // 								| 'child' 
         // 								| 'descendant' 
         // 								| 'descendant-or-self' 
         // 								| 'following' 
         // 								| 'following-sibling' 
         // 								| 'namespace' 
         // 								| 'parent' 
         // 								| 'preceding' 
         // 								| 'preceding-sibling' 
         // 								| 'self'
   
         if (! ltp_get (0))
            return false;
         if (! o_is_axis_name (ltp_get (0) -> lex_get_value ()))
            return false;
         if (o_final)
            v_action (xpath_axis_name, 0, ltp_get (0) -> lex_get_value ());
         v_inc_current (1);
         break;

      case xpath_node_test :
         // [7]   NodeTest				::=   NameTest 
         // 								| NodeType '(' ')' 
         // 								| 'processing-instruction' '(' Literal ')'
         // [38]   NodeType				::=   'comment' 
			// 				| 'text' 
			// 				| 'processing-instruction' 
			// 				| 'node' 
         if (! ltp_get (0))
            return false;
         switch (ltp_get (0) -> lex_get_value ())
         {
            case lex_comment :
            case lex_text :
            case lex_node :
               if (o_final)
                  v_action (xpath_node_test, xpath_node_test_reserved_keyword, ltp_get (0) -> lex_get_value ());
               v_inc_current (3);
               break;
            case lex_processing_instruction :
               if (ltp_get (2) && ltp_get (2) -> lex_get_value () == lex_cparen)
               {
                  // single
                  v_inc_current (3);
                  if (o_final)
                     v_action (xpath_node_test, xpath_node_test_pi, lex_processing_instruction);
               }
               else
               {
                  // with literal
                  v_inc_current (3);
                  if (o_final)
                     v_action (xpath_node_test, xpath_node_test_pi_lit, lex_processing_instruction, ltp_get (0) -> cp_get_literal ());
                  v_inc_current (1);
               }
               break;
            default :
               if (! o_recognize (xpath_name_test, o_final))
                  return false;
               if (o_final)
                  v_action (xpath_node_test, xpath_node_test_name_test);
         }
         break;

      case xpath_predicate :
         // [8]   Predicate				::=   '[' PredicateExpr ']' 
         if (! ltp_get (1))
            return false;
         if (ltp_get (0) -> lex_get_value () != lex_obrack)
            return false;
         v_inc_current (1);
         if (! o_recognize (xpath_predicate_expr, o_final))
            return false;
         if (! ltp_get (0) || ltp_get (0) -> lex_get_value () != lex_cbrack)
            return false;
         v_inc_current (1);
         if (o_final)
            v_action (xpath_predicate, 0);
         break;

      case xpath_predicate_expr :
         // [9]   PredicateExpr			::=   Expr
         if (! o_recognize (xpath_expr, o_final))
            return false;
         if (o_final)
            v_action (xpath_predicate_expr, 0);
         break;

      case xpath_abbreviated_absolute_location_path :
         // [10]   AbbreviatedAbsoluteLocationPath	::=   '//' RelativeLocationPath 
         if (! ltp_get (0) || ltp_get (0) -> lex_get_value () != lex_2_slash)
            return false;
         v_inc_current (1);
         if (! o_recognize (xpath_relative_location_path, o_final))
            return false;
         if (o_final)
            v_action (xpath_abbreviated_absolute_location_path, 0);
         break;

      // Note : [11] is processed by [3]

      case xpath_abbrieviated_step :
         // [12]   AbbreviatedStep					::=   '.' | '..' 
         if (! ltp_get (0))
            return false;
         switch (ltp_get (0) -> lex_get_value ())
         {
            case lex_dot :
               v_inc_current (1);
               if (o_final)
                  v_action (xpath_abbrieviated_step, 0);
               break;
            case lex_2_dot :
               v_inc_current (1);
               if (o_final)
                  v_action (xpath_abbrieviated_step, 1);
               break;
            default :
               return false;
         }
         break;

      // Note : [13] processed by [5]

      case xpath_expr :
         //
         // [14]   Expr					::=   OrExpr 
         //
         if (! ltp_get (0))
            return false;
         if (! o_recognize (xpath_or_expr, o_final))
            return false;
         if (o_final)
            v_action (xpath_expr, 0);
         break;

      case xpath_primary_expr :
         // [15]   PrimaryExpr			::=   VariableReference
			// 				            | '(' Expr ')' 
			// 				            | Literal 
			// 				            | Number 
			// 				            | FunctionCall
         if (! ltp_get (0))
            return false;
         switch (ltp_get (0) -> lex_get_value ())
         {
            case lex_dollar :
               if (! o_recognize (xpath_variable_reference, o_final))
                  return false;
               if (o_final)
                  v_action (xpath_primary_expr, xpath_primary_expr_variable);
               break;
            case lex_oparen :
               v_inc_current (1);
               if (! o_recognize (xpath_expr, o_final))
                  return false;
               if (! ltp_get (0) || ltp_get (0) -> lex_get_value () != lex_cparen)
                  return false;
               v_inc_current (1);
               if (o_final)
                  v_action (xpath_primary_expr, xpath_primary_expr_paren_expr);
               break;
            case lex_literal :
               if (o_final)
                  v_action (xpath_primary_expr, xpath_primary_expr_literal, 0, ltp_get (0) -> cp_get_literal ());
               v_inc_current (1);
               break;
            case lex_number :
               if (o_final)
                  v_action (xpath_primary_expr, xpath_primary_expr_number, 0, ltp_get (0) -> cp_get_literal ());
               v_inc_current (1);
               break;
            default :
               if (! o_recognize (xpath_function_call, o_final))
                  return false;
               if (o_final)
                  v_action (xpath_primary_expr, xpath_primary_expr_function_call);
               break;
         }
         break;

      case xpath_function_call :
         // [16]   FunctionCall			::=   FunctionName '(' ( Argument ( ',' Argument )* )? ')' 
         // [35]   FunctionName	      ::=  	QName - NodeType
         if (! ltp_get (0))
            return false;
         switch (ltp_get (0) -> lex_get_value ())
         {
            case lex_comment :
            case lex_text :
            case lex_node :
            case lex_processing_instruction :
               if (o_final)
               {
                  v_action (xpath_xml_local_part, 0, 0, ltp_get (0) -> cp_get_literal ());
                  v_action (xpath_xml_q_name, xpath_xml_q_name_simple);         
               }
               v_inc_current (1);
               break;
            default :
               if (! o_recognize (xpath_xml_q_name, o_final))
                  return false;
         }
         if (! ltp_get (0) || ltp_get (0) -> lex_get_value () != lex_oparen)
            return false;
         v_inc_current (1);
         if (! ltp_get (0))
            return false;
         if (ltp_get (0) -> lex_get_value () == lex_cparen)
         {
            v_inc_current (1);
            if (o_final)
               v_action (xpath_function_call, 0);
         }
         else
         {
            ltp_freeze = ltp_get (0);
            o_found = true;
            u_nb_argument = 0;
            while (o_found)
            {
               if (u_nb_argument)
               {
                  if (! ltp_get (0) || ltp_get (0) -> lex_get_value () != lex_comma)
                     o_found = false;
                  else
                     v_inc_current (1);
               }
               if (o_found)
               {
                  if (! o_recognize (xpath_argument, o_final))
                     o_found = false;
                  else
                  {
                     u_nb_argument++;
                     ltp_freeze = ltp_get (0);
                  }
               }
            }
            v_set_current (ltp_freeze);
            if (! ltp_get (0) || ltp_get (0) -> lex_get_value () != lex_cparen)
               return false;
            v_inc_current (1);
            if (o_final)
               v_action (xpath_function_call, 1, u_nb_argument);
         }
         break;

      case xpath_argument :
         // [17]   Argument				::=   Expr
         if (! o_recognize (xpath_expr, o_final))
            return false;
         if (o_final)
            v_action (xpath_argument, 0);
         break;

      case xpath_union_expr :
         //
         // [18]   UnionExpr			::=   PathExpr 
			// 					         | UnionExpr '|' PathExpr 
         //
         if (! o_recognize (xpath_path_expr, o_final))
            return false;
         if (ltp_get (0) && ltp_get (0) -> lex_get_value () == lex_orchar)
         {
            v_inc_current (1);
            if (! o_recognize (xpath_union_expr, o_final))
               return false;
            if (o_final)
               v_action (xpath_union_expr, xpath_union_expr_union);
         }
         else
            if (o_final)
               v_action (xpath_union_expr, xpath_union_expr_simple);
         break;

      case xpath_path_expr :
         //
         // [19]   PathExpr				::=   LocationPath 
         // 	        							| FilterExpr 
         // 			      					| FilterExpr '/' RelativeLocationPath 
         // 					      			| FilterExpr '//' RelativeLocationPath 
         //
         ltp_freeze = ltp_get (0);
         o_location_path = false;

         if (! o_recognize (xpath_filter_expr, false))
            o_location_path = true;
         else
         {
            v_set_current (ltp_freeze);
            o_recognize (xpath_filter_expr, o_final);
            if (ltp_get (0) && ltp_get (0) -> lex_get_value () == lex_slash)
            {
               v_inc_current (1);
               if (! o_recognize (xpath_relative_location_path, o_final))
                  o_location_path = true;
               else
                  if (o_final)
                     v_action (xpath_path_expr, xpath_path_expr_slash);
            }
            else
               if (ltp_get (0) && ltp_get (0) -> lex_get_value () == lex_2_slash)
               {
                  v_inc_current (1);
                  if (! o_recognize (xpath_relative_location_path, o_final))
                     o_location_path = true;
                  else
                     if (o_final)
                        v_action (xpath_path_expr, xpath_path_expr_2_slash);
               }
               else
               {
                  if (o_final)
                     v_action (xpath_path_expr, xpath_path_expr_filter);
               }
         }

         if (o_location_path)
         {
            v_set_current (ltp_freeze);
            if (! o_recognize (xpath_location_path, o_final))
               return false;
            if (o_final)
               v_action (xpath_path_expr, xpath_path_expr_location_path);
         }
         break;

      case xpath_filter_expr :
         //
         // [20]   FilterExpr			::=   PrimaryExpr 
			// 				            | FilterExpr Predicate
         //
         if (! o_recognize (xpath_primary_expr, o_final))
            return false;
         if (ltp_get (0) && ltp_get (0) -> lex_get_value () == lex_obrack)
         {
            if (! o_recognize (xpath_predicate, o_final))
               return false;
            if (o_final)
               v_action (xpath_filter_expr, xpath_filter_expr_predicate);
         }
         else
            if (o_final)
               v_action (xpath_filter_expr, xpath_filter_expr_primary);
         break;

      case xpath_or_expr :
         //
         // [21]   OrExpr				::=   AndExpr 
			// 					         | OrExpr 'or' AndExpr 
         //
         o_test_more = false;
         if (! o_recognize (xpath_and_expr, o_final))
            return false;
         if (ltp_get (0) && ltp_get (0) -> lex_get_value () == lex_or)
         {
            v_inc_current (1);
            if (! o_recognize (xpath_and_expr, o_final))
               return false;
            if (o_final)
               v_action (xpath_or_expr, xpath_or_expr_or);
            o_test_more = true;
         }
         else
            if (o_final)
               v_action (xpath_or_expr, xpath_or_expr_simple);
         if (o_test_more)
         {
            while (ltp_get (0) && (ltp_get (0) ->lex_get_value () == lex_or ))
            {
               v_inc_current (1);
               if (! o_recognize (xpath_and_expr, o_final))
                  return false;
               if (o_final)
                  v_action (xpath_or_expr, xpath_or_expr_more);				
            } 
         }		
         break;

      case xpath_and_expr :
         //
         // [22]   AndExpr				::=   EqualityExpr 
         // 								| AndExpr 'and' EqualityExpr 
         //
         if (! o_recognize (xpath_equality_expr, o_final))
            return false;
         if (ltp_get (0) && ltp_get (0) -> lex_get_value () == lex_and)
         {
            v_inc_current (1);
            if (! o_recognize (xpath_equality_expr, o_final))
               return false;
            if (o_final)
               v_action (xpath_and_expr, xpath_and_expr_and);
         }
         else
            if (o_final)
               v_action (xpath_and_expr, xpath_and_expr_simple);
         break;

      case xpath_equality_expr :
         //
         // [23]   EqualityExpr			::=   RelationalExpr 
			// 					         | EqualityExpr '=' RelationalExpr 
			// 					         | EqualityExpr '!=' RelationalExpr 
         //
         if (! o_recognize (xpath_relational_expr, o_final))
            return false;
         if (ltp_get (0))
         {
            switch (ltp_get (0) -> lex_get_value ())
            {
               case lex_equal :
                  v_inc_current (1);
                  if (! o_recognize (xpath_relational_expr, o_final))
                     return false;
                  if (o_final)
                     v_action (xpath_equality_expr, xpath_equality_expr_equal);
                  break;

               case lex_not_equal :
                  v_inc_current (1);
                  if (! o_recognize (xpath_relational_expr, o_final))
                     return false;
                  if (o_final)
                     v_action (xpath_equality_expr, xpath_equality_expr_not_equal);
                  break;

               default :
                  if (o_final)
                     v_action (xpath_equality_expr, xpath_equality_expr_simple);
                  break;
            }
         }
         else
         {
            if (o_final)
               v_action (xpath_equality_expr, xpath_equality_expr_simple);
         }
         break;

      case xpath_relational_expr :
         //
         // [24]   RelationalExpr		::=   AdditiveExpr 
			// 					         | RelationalExpr '<' AdditiveExpr 
			// 					         | RelationalExpr '>' AdditiveExpr 
			// 					         | RelationalExpr '<=' AdditiveExpr 
			// 					         | RelationalExpr '>=' AdditiveExpr
         //
         if (! o_recognize (xpath_additive_expr, o_final))
            return false;
         if (ltp_get (0))
         {
            switch (ltp_get (0) -> lex_get_value ())
            {
               case lex_lt :
                  v_inc_current (1);
                  if (! o_recognize (xpath_additive_expr, o_final))
                     return false;
                  if (o_final)
                     v_action (xpath_relational_expr, xpath_relational_expr_lt);
                  break;
               case lex_gt :
                  v_inc_current (1);
                  if (! o_recognize (xpath_additive_expr, o_final))
                     return false;
                  if (o_final)
                     v_action (xpath_relational_expr, xpath_relational_expr_gt);
                  break;
               case lex_lt_equal :
                  v_inc_current (1);
                  if (! o_recognize (xpath_additive_expr, o_final))
                     return false;
                  if (o_final)
                     v_action (xpath_relational_expr, xpath_relational_expr_lte);
                  break;
               case lex_gt_equal :
                  v_inc_current (1);
                  if (! o_recognize (xpath_additive_expr, o_final))
                     return false;
                  if (o_final)
                     v_action (xpath_relational_expr, xpath_relational_expr_gte);
                  break;
               default :
                  if (o_final)
                     v_action (xpath_relational_expr, xpath_relational_expr_simple);
                  break;
            }     // switch
         }
         else
            if (o_final)
               v_action (xpath_relational_expr, xpath_relational_expr_simple);
         break;

      case xpath_additive_expr :
         // 
         // [25]   AdditiveExpr			::=   MultiplicativeExpr 
			// 					         | AdditiveExpr '+' MultiplicativeExpr 
			// 					         | AdditiveExpr '-' MultiplicativeExpr 
         // 
         if (! o_recognize (xpath_multiplicative_expr, o_final))
            return false;
         o_test_more = false;
         if (ltp_get (0))
         {
            switch (ltp_get (0) -> lex_get_value ())
            {
               case lex_plus :
                  v_inc_current (1);
                  if (! o_recognize (xpath_multiplicative_expr, o_final))
                     return false;
                  if (o_final)
                     v_action (xpath_additive_expr, xpath_additive_expr_plus);
                  o_test_more = true;
                  break;
               case lex_minus :
                  v_inc_current (1);
                  if (! o_recognize (xpath_multiplicative_expr, o_final))
                     return false;
                  if (o_final)
                     v_action (xpath_additive_expr, xpath_additive_expr_minus);
                  o_test_more = true;
                  break;
               default :
                  if (o_final)
                     v_action (xpath_additive_expr, xpath_additive_expr_simple);
                  break;
            }     // switch
         }
         else
            if (o_final)
               v_action (xpath_additive_expr, xpath_additive_expr_simple);
         if (o_test_more)
         {
            while (ltp_get (0) && (ltp_get (0) -> lex_get_value () == lex_plus || ltp_get (0) -> lex_get_value () == lex_minus))
            {
               if (ltp_get (0) -> lex_get_value () == lex_plus)
               {
                  v_inc_current (1);
                  if (! o_recognize (xpath_multiplicative_expr, o_final))
                     return false;
                  if (o_final)
                     v_action (xpath_additive_expr, xpath_additive_expr_more_plus);
               }
               else
               {
                  v_inc_current (1);
                  if (! o_recognize (xpath_multiplicative_expr, o_final))
                     return false;
                  if (o_final)
                     v_action (xpath_additive_expr, xpath_additive_expr_more_minus);
               }
            } 
         }
         break;

      case xpath_multiplicative_expr :
         //
         // [26]   MultiplicativeExpr   ::=   UnaryExpr 
			// 					         | MultiplicativeExpr MultiplyOperator UnaryExpr 
			// 					         | MultiplicativeExpr 'div' UnaryExpr 
			// 					         | MultiplicativeExpr 'mod' UnaryExpr 
         //
         if (! o_recognize (xpath_unary_expr, o_final))
            return false;
         if (ltp_get (0))
         {
            switch (ltp_get (0) -> lex_get_value ())
            {
               case lex_star :
                  //
                  // [34]   MultiplyOperator		::=   '*' 
                  //
                  v_inc_current (1);
                  if (! o_recognize (xpath_unary_expr, o_final))
                     return false;
                  if (o_final)
                     v_action (xpath_multiplicative_expr, xpath_multiplicative_expr_star);
                  break;
               case lex_div :
                  v_inc_current (1);
                  if (! o_recognize (xpath_unary_expr, o_final))
                     return false;
                  if (o_final)
                     v_action (xpath_multiplicative_expr, xpath_multiplicative_expr_div);
                  break;
               case lex_mod :
                  v_inc_current (1);
                  if (! o_recognize (xpath_unary_expr, o_final))
                     return false;
                  if (o_final)
                     v_action (xpath_multiplicative_expr, xpath_multiplicative_expr_mod);
                  break;
               default :
                  if (o_final)
                     v_action (xpath_multiplicative_expr, xpath_multiplicative_expr_simple);
                  break;
            }
         }
         else
            if (o_final)
               v_action (xpath_multiplicative_expr, xpath_multiplicative_expr_simple);
         break;

      case xpath_unary_expr :
         //
         // [27]   UnaryExpr			::=   UnionExpr 
			// 					         | '-' UnaryExpr
         //
         if (ltp_get (0) && ltp_get (0) -> lex_get_value () == lex_minus)
         {
            v_inc_current (1);
            if (! o_recognize (xpath_unary_expr, o_final))
               return false;
            if (o_final)
               v_action (xpath_unary_expr, xpath_unary_expr_minus);
         }
         else
         {
            if (! o_recognize (xpath_union_expr, o_final))
               return false;
            if (o_final)
               v_action (xpath_unary_expr, xpath_unary_expr_simple);
         }
         break;

      case xpath_variable_reference :
         // [36]   VariableReference	::=   '$' QName 
         if (! ltp_get (0) || ! ltp_get (1))
            return false;
         if (ltp_get (0) -> lex_get_value () != lex_dollar)
            return false;
         v_inc_current (1);
         if (! o_recognize (xpath_xml_q_name, o_final))
            return false;
         if (o_final)
            v_action (xpath_variable_reference, 0);
         break;

      case xpath_name_test :
         // [37]   NameTest				::=   '*' 
			// 				            | NCName ':' '*' 
			// 				            | QName 
         if (! ltp_get (0))
            return false;
         switch (ltp_get (0) -> lex_get_value ())
         {
            case lex_star :
               v_inc_current (1);
               if (o_final)
                  v_action (xpath_name_test, xpath_name_test_star);
               break;
            case lex_ncname :
               o_qname = false;
               if (ltp_get (1) && ltp_get (2) && 
                   ltp_get (1) -> lex_get_value () == lex_colon)
               {
                  if (ltp_get (2) -> lex_get_value () == lex_star)
                  {
                     v_inc_current (3);
                     if (o_final)
                        v_action (xpath_name_test, xpath_name_test_ncname);
                  }
                  else
                     o_qname = true;
               }
               else
                  o_qname = true;
               if (o_qname)
               {
                  if (! o_recognize (xpath_xml_q_name, o_final))
                     return false;
                  if (o_final)
                     v_action (xpath_name_test, xpath_name_test_qname);
               }
               break;
         }
         break;

      case xpath_xml_q_name :
         // [Namespace XML : 6] QName					::= (Prefix ':')? LocalPart 
         // [Namespace XML : 7] Prefix					::= NCName 
         // [Namespace XML : 8] LocalPart				::= NCName
         if (! ltp_get (0) || ltp_get (0) -> lex_get_value () != lex_ncname)
            return false;
         if (ltp_get (1) && ltp_get (1) -> lex_get_value () == lex_colon)
         {
            if (! ltp_get (2) || ltp_get (2) -> lex_get_value () != lex_ncname)
               return false;
            if (o_final)
            {
               v_action (xpath_xml_prefix, 0, 0, ltp_get (0) -> cp_get_literal ());
               v_action (xpath_xml_local_part, 0, 0, ltp_get (2) -> cp_get_literal ());
               v_action (xpath_xml_q_name, xpath_xml_q_name_colon);
            }
            v_inc_current (3);
         }
         else
         {
            if (o_final)
            {
               v_action (xpath_xml_local_part, 0, 0, ltp_get (0) -> cp_get_literal ());
               v_action (xpath_xml_q_name, xpath_xml_q_name_simple);
            }
            v_inc_current (1);
         }
         break;

      default :
         if (o_final)
            v_action (xpath_unknown, 0);
         return false;
         break;
   }
   return true;
}     // v_recognize ()