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/*

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 * (c) 2003 Mario de Sousa

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 *

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 * Offered to the public under the terms of the GNU General Public License

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 * as published by the Free Software Foundation; either version 2 of the

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 * License, or (at your option) any later version.

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 *

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 * This program is distributed in the hope that it will be useful, but

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 * WITHOUT ANY WARRANTY; without even the implied warranty of

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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General

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 * Public License for more details.

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 *

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 * This code is made available on the understanding that it will not be

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 * used in safety-critical situations without a full and competent review.

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 */

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/*

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 * An IEC 61131-3 IL and ST compiler.

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 *

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 * Based on the

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 * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)

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 *

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 */

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/* Determine the data type of a variable.

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 * The variable may be a simple variable, a function block instance, a

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 * struture element within a data structured type (a struct or a fb), or

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 * an array element.

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 * A mixture of array element of a structure element of a structure element

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 * of a .... is also suported!

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 *

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 * A reference to the relevant base type __definition__ is returned.

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 * This means that if we find that the variable is of type MY_INT,

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 * which was previously declared to be

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 * TYPE MY_INT: INT := 9;

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 * this class wil return INT, and __not__ MY_INT !!

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 *

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 *

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 *  example:

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 *    window.points[1].coordinate.x

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 *    window.points[1].colour

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 *    etc... ARE ALLOWED!

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 *

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 * This class must be passed the scope within which the

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 * variable was declared, and the variable name...

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 */

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class search_varfb_instance_type_c: public search_base_type_c {

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  private:

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    search_var_instance_decl_c search_var_instance_decl;

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    decompose_var_instance_name_c *decompose_var_instance_name;

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    symbol_c *current_structelement_name;

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  public:

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    search_varfb_instance_type_c(symbol_c *search_scope): search_var_instance_decl(search_scope) {

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      this->decompose_var_instance_name = NULL;

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      this->current_structelement_name = NULL;

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    }

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    symbol_c *get_type(symbol_c *variable_name) {

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      this->current_structelement_name = NULL;

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      this->decompose_var_instance_name = new decompose_var_instance_name_c(variable_name);

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      if (NULL == decompose_var_instance_name) ERROR;

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      /* find the part of the variable name that will appear in the

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       * variable declaration, for e.g., in window.point.x, this would be

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       * window!

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       */

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      symbol_c *var_name_part = decompose_var_instance_name->next_part();

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      if (NULL == var_name_part) ERROR;

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      /* Now we try to find the variable instance declaration, to determine its type... */

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      symbol_c *var_decl = search_var_instance_decl.get_decl(var_name_part);

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      if (NULL == var_decl) {

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        /* variable instance declaration not found! */

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 	return NULL;

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      }

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      /* if it is a struct or function block, we must search the type

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       * of the struct or function block member.

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       * This is done by this class visiting the var_decl.

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       * This class, while visiting, will recursively call

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       * decompose_var_instance_name->get_next() when and if required...

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       */

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      symbol_c *res = (symbol_c *)var_decl->accept(*this);

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      if (NULL == res) ERROR;

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      /* make sure that we have decomposed all strcuture elements of the variable name */

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      symbol_c *var_name = decompose_var_instance_name->next_part();

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      if (NULL != var_name) ERROR;

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      return res;

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    }

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  private:

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    /* a helper function... */

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    void *visit_list(list_c *list)	{

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      if (NULL == current_structelement_name) ERROR;

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      for(int i = 0; i < list->n; i++) {

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        void *res = list->elements[i]->accept(*this);

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        if (res != NULL)

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          return res;

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      }

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      /* not found! */

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      return NULL;

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    }

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    /* a helper function... */

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    void *base_type(symbol_c *symbol)	{

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        search_base_type_c search_base_type;

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	return symbol->accept(search_base_type);

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    }

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  private:

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    /* We override the base class' visitor to identifier_c.

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     * This is so because the base class does not consider a function block

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     * to be a type, unlike this class that allows a variable instance

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     * of a function block type...

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     */

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    void *visit(identifier_c *type_name) {

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      /* look up the type declaration... */

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      symbol_c *fb_decl = function_block_type_symtable.find_value(type_name);

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      if (fb_decl != function_block_type_symtable.end_value())

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        /* Type declaration found!! */

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	return fb_decl->accept(*this);

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      /* No. It is not a function block, so we let

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       * the base class take care of it...

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       */

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      return search_base_type_c::visit(type_name);

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    }

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/********************************/

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/* B 1.3.3 - Derived data types */

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/********************************/

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/*  structure_type_name ':' structure_specification */

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    void *visit(structure_type_declaration_c *symbol) {

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      return symbol->structure_specification->accept(*this);

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      /* NOTE: structure_specification will point to either a

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       *       initialized_structure_c

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       *       OR A

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       *       structure_element_declaration_list_c

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       */

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    }

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/* structure_type_name ASSIGN structure_initialization */

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/* structure_initialization may be NULL ! */

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// SYM_REF2(initialized_structure_c, structure_type_name, structure_initialization)

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    void *visit(initialized_structure_c *symbol)	{

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      /* make sure that we have decomposed all strcuture elements of the variable name */

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      symbol_c *var_name = decompose_var_instance_name->next_part();

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      if (NULL == var_name) {

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        /* this is it... !

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	  * No need to look any further...

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	 */

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	/* NOTE: we could simply do a

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	 *   return (void *)symbol;

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	 *       nevertheless, note that this search_varfb_instance_type_c

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	 *       class inherits from the search_base_type_c class,

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	 *       which means that it will usually return the base type,

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	 *       and not the derived type (*). If we are to be consistent,

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	 *       we should guarantee that we always return the base type.

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	 *       To do this we could use

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	 *   return (void *)symbol->accept(*this);

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	 *       since this class inherits from the search_base_type_c.

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	 *       However, in this case we don't want it to follow

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	 *       the structs as this search_varfb_instance_type_c does.

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	 *       We therefore have to create a new search_base_type_c

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	 *       instance to search through this type without going

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	 *       through the structs...

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	 */

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        return base_type(symbol->structure_type_name);

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      }

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      /* now search the structure declaration */

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      current_structelement_name = var_name;

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      /* recursively find out the data type of var_name... */

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      return symbol->structure_type_name->accept(*this);

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    }

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/* helper symbol for structure_declaration */

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/* structure_declaration:  STRUCT structure_element_declaration_list END_STRUCT */

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/* structure_element_declaration_list structure_element_declaration ';' */

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    void *visit(structure_element_declaration_list_c *symbol)	{return visit_list(symbol);}

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/*  structure_element_name ':' spec_init */

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    void *visit(structure_element_declaration_c *symbol) {

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      if (NULL == current_structelement_name) ERROR;

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      if (compare_identifiers(symbol->structure_element_name, current_structelement_name) == 0)

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        return symbol->spec_init->accept(*this);

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      return NULL;

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    }

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/* helper symbol for structure_initialization */

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/* structure_initialization: '(' structure_element_initialization_list ')' */

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/* structure_element_initialization_list ',' structure_element_initialization */

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    void *visit(structure_element_initialization_list_c *symbol) {ERROR; return NULL;} /* should never get called... */

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/*  structure_element_name ASSIGN value */

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    void *visit(structure_element_initialization_c *symbol) {ERROR; return NULL;} /* should never get called... */

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/**************************************/

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/* B.1.5 - Program organization units */

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/**************************************/

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/*****************************/

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/* B 1.5.2 - Function Blocks */

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/*****************************/

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/*  FUNCTION_BLOCK derived_function_block_name io_OR_other_var_declarations function_block_body END_FUNCTION_BLOCK */

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// SYM_REF4(function_block_declaration_c, fblock_name, var_declarations, fblock_body, unused)

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    void *visit(function_block_declaration_c *symbol) {

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      /* make sure that we have decomposed all strcuture elements of the variable name */

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      symbol_c *var_name = decompose_var_instance_name->next_part();

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      if (NULL == var_name) {

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        /* this is it... !

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	 * No need to look any further...

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	 * Note also that, unlike for the struct types, a function block may

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	 * not be defined based on another (i.e. no inheritance is allowed),

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	 * so this function block is already the most base type.

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	 * We simply return it.

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	 */

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	return (void *)symbol;

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      }

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      /* now search the function block declaration for the variable... */

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      search_var_instance_decl_c search_decl(symbol);

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      symbol_c *var_decl = search_decl.get_decl(var_name);

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      if (NULL == var_decl) {

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        /* variable instance declaration not found! */

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 	return NULL;

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      }

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      /* We have found the declaration.

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       * Should we look any further?

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       */

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      var_name = decompose_var_instance_name->next_part();

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      if (NULL == var_name) {

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        /* this is it... ! */

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	return base_type(var_decl);

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      }

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      current_structelement_name = var_name;

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      /* recursively find out the data type of var_name... */

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      return symbol->var_declarations->accept(*this);

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    }

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};

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