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/*

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 *  matiec - a compiler for the programming languages defined in IEC 61131-3

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 *

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 *  Copyright (C) 2003-2012  Mario de Sousa (msousa@fe.up.pt)

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 *  Copyright (C) 2007-2011  Laurent Bessard and Edouard Tisserant

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 *

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 *  This program is free software: you can redistribute it and/or modify

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 *  it under the terms of the GNU General Public License as published by

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 *  the Free Software Foundation, either version 3 of the License, or

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 *  (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,

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 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

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 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

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 *  GNU General Public License for more details.

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 *

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 *  You should have received a copy of the GNU General Public License

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 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.

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 *

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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 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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 *  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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 *

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 *

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 *

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 *

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 * This class has several members, depending on the exact data the caller

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 * is looking for...

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 *

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 *    - item i: we can get either the name of the data type(A),

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 *              or it's declaration (B)

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 *             (notice however that some variables belong to a data type that does

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 *              not have a name, only a declaration as in

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 *              VAR a: ARRAY [1..3] of INT; END_VAR

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 *             )

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 *    - item ii: we can get either the direct data type (1), 

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 *               or the base type (2)

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 * 

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 *   By direct type, I mean the data type of the variable. By base type, I 

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 * mean the data type on which the direct type is based on. For example, in 

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 * a subrange on INT, the direct type is the subrange itself, while the 

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 * base type is INT.

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 * e.g.

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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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 *   option (1) will return MY_INT

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 *   option (2) will return INT

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 * 

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 *

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 * Member functions:

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 * ================

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 *   get_basetype_id()    ---> returns 2A   (implemented, although currently it is not needed! )

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 *   get_basetype_decl()  ---> returns 2B 

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 *   get_type_id()        ---> returns 1A

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 * 

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 *   Since we haven't yet needed it, we don't yet implement

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 *   get_type_decl()      ---> returns 1B 

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 */ 

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#include "absyntax_utils.hh"

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void search_varfb_instance_type_c::init(void) {

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  this->current_type_id        = NULL;

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  this->current_basetype_id    = NULL;

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  this->current_basetype_decl  = NULL;

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  this->current_field_selector = NULL;

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}

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

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  this->init();

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}

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/* We expect to be passed a symbolic_variable_c */

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symbol_c *search_varfb_instance_type_c::get_type_id(symbol_c *variable_name) {

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  this->init();

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  variable_name->accept(*this);

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  return current_type_id;

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}

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symbol_c *search_varfb_instance_type_c::get_basetype_id(symbol_c *variable_name) {

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  this->init();

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  variable_name->accept(*this);

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  return current_basetype_id;

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}

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symbol_c *search_varfb_instance_type_c::get_basetype_decl(symbol_c *variable_name) {

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  this->init();

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  variable_name->accept(*this);

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  return current_basetype_decl;

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}  

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

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/* B.1 - Common elements */

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

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

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/* B 1.1 - Letters, digits and identifiers */

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

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// SYM_TOKEN(identifier_c)

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void *search_varfb_instance_type_c::visit(identifier_c *variable_name) {

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  /* symbol should be a variable name!! */

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  /* Note: although the method is called get_decl(), it is getting the declaration of the variable, which for us is the type_id of that variable! */

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  current_type_id       = search_var_instance_decl.get_decl (variable_name);

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  current_basetype_decl = search_base_type.get_basetype_decl(current_type_id);

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  current_basetype_id   = search_base_type.get_basetype_id  (current_type_id);

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  /* What if the variable has not been declared?  Then this should not be a compiler error! 

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   * However, currently stage 2 of the compiler already detects when variables have not been delcared,

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   * so if the variable's declaration is not found, then that means that we have an internal compiler error!

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   */

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  if (NULL == current_type_id) ERROR; 

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  return NULL;

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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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/*  identifier ':' array_spec_init */

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/* NOTE: I don't think this will ever get called, since in the visit method for array_variable_c

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 * we use the basetype_decl for recursively calling this class, and the base type should never be a 

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 * array_type_declaration_c, but for now, let's leave it in...

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 */

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void *search_varfb_instance_type_c::visit(array_type_declaration_c *symbol) {

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  ERROR;

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  return NULL;

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}

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/* array_specification [ASSIGN array_initialization] */

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/* array_initialization may be NULL ! */

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/* NOTE: I don't think this will ever get called, since in the visit method for array_variable_c

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 * we use the basetype_decl for recursively calling this class, and the base type should never be a 

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 * array_spec_init_c, but for now, let's leave it in...

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 */

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void *search_varfb_instance_type_c::visit(array_spec_init_c *symbol) {

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  /* Note that the 'array_specification' may be either an identifier of a previsously defined array type, 

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   * or an array_specification_c, so we can not stop here and simply return a array_spec_init_c, 

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   * especially if we are looking for the base class!

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   */

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  ERROR;

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  return NULL;

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}

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/* ARRAY '[' array_subrange_list ']' OF non_generic_type_name */

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/* NOTE: This method will be reached after being called from the 

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 * search_varfb_instance_type_c::visit(array_variable_c *symbol)

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 * method, so we must return the data type of the data stored in the array, 

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 * and not the data type of the array itself!

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 */

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void *search_varfb_instance_type_c::visit(array_specification_c *symbol) {

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  /* found the type of the element we were looking for! */

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  current_type_id       = symbol->non_generic_type_name;

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  current_basetype_decl = search_base_type.get_basetype_decl(current_type_id);

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  current_basetype_id   = search_base_type.get_basetype_id  (current_type_id);

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  return NULL; 

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}

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/*  structure_type_name ':' structure_specification */

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/* NOTE: this is only used inside a TYPE ... END_TYPE declaration. 

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 * It is never used directly when declaring a new variable! 

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 */

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/* NOTE: I don't think this will ever get called, since in the visit method for structured_variable_c

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 * we use the basetype_decl for recursively calling this class, and the base type should never be a 

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 * structure_type_declaration_c, but for now, let's leave it in...

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 */

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void *search_varfb_instance_type_c::visit(structure_type_declaration_c *symbol) {

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  if (NULL == current_field_selector) ERROR;

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

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  return NULL;

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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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/* NOTE: only the initialized structure is never used when declaring a new variable instance */

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/* NOTE: I don't think this will ever get called, since in the visit method for structured_variable_c

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 * we use the basetype_decl for recursively calling this class, and the base type should never be a 

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 * initialized_structure_c, but for now, let's leave it in...

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 */

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void *search_varfb_instance_type_c::visit(initialized_structure_c *symbol)	{

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  if (NULL != current_field_selector) ERROR;

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

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

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  return NULL;

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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 *search_varfb_instance_type_c::visit(structure_element_declaration_list_c *symbol)	{

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  if (NULL == current_field_selector) ERROR;

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  /* now search the structure declaration */

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

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    symbol->elements[i]->accept(*this);

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  }

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  return NULL;

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}

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/*  structure_element_name ':' spec_init */

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void *search_varfb_instance_type_c::visit(structure_element_declaration_c *symbol) {

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  if (NULL == current_field_selector) ERROR;

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  if (compare_identifiers(symbol->structure_element_name, current_field_selector) == 0) {

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    /* found the type of the element we were looking for! */

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    current_type_id       = symbol->spec_init;

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    current_basetype_decl = search_base_type.get_basetype_decl(current_type_id);

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    current_basetype_id   = search_base_type.get_basetype_id  (current_type_id);

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  }  

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  /* Did not find the type of the element we were looking for! */

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  /* Will keep looking... */

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

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

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/* B 1.4 - Variables */

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

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// SYM_REF1(symbolic_variable_c, var_name)

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void *search_varfb_instance_type_c::visit(symbolic_variable_c *symbol) {

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  symbol->var_name->accept(*this);

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  return NULL;

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}

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

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/* B.1.4.1   Directly Represented Variables */

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

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// SYM_TOKEN(direct_variable_c)

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/* We do not yet handle this. Will we ever need to handle it, as the data type of the direct variable is

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 * directly obtainable from the syntax of the direct variable itself?

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 */

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

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/* B 1.4.2 - Multi-element variables */

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

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/*  subscripted_variable '[' subscript_list ']' */

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// SYM_REF2(array_variable_c, subscripted_variable, subscript_list)

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/* NOTE: when passed a array_variable_c, which represents some IEC61131-3 code similar to X[42]

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 * we must return the data type of the value _stored_ in the array.

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 * If you want to get the data type of the array itself (i.e. just the X variable, without the [42])

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 * then this class must be called with the identifier_c 'X'.

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 */

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void *search_varfb_instance_type_c::visit(array_variable_c *symbol) {

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  /* determine the data type of the subscripted_variable... 

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   * This should be an array_specification_c

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   *    ARRAY [xx..yy] OF Stored_Data_Type

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   */

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  symbol->subscripted_variable->accept(*this);

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  /* Now we determine the 'Stored_Data_Type', i.e. the data type of the variable stored in the array. */

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  if (NULL != current_basetype_decl) {

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    current_basetype_decl->accept(*this);

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  }

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  return NULL;

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}

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/*  record_variable '.' field_selector */

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/*  WARNING: input and/or output variables of function blocks

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 *           may be accessed as fields of a structured variable!

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 *           Code handling a structured_variable_c must take

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 *           this into account!

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 */

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// SYM_REF2(structured_variable_c, record_variable, field_selector)

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void *search_varfb_instance_type_c::visit(structured_variable_c *symbol) {

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  symbol->record_variable->accept(*this);

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  /* Now we search for the data type of the field... But only if we were able to determine the data type of the variable */

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  if (NULL != current_basetype_decl) {

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    current_field_selector = symbol->field_selector;

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    current_basetype_decl->accept(*this);

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    current_field_selector = NULL;

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  }

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  return NULL;

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}

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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 *search_varfb_instance_type_c::visit(function_block_declaration_c *symbol) {

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  if (NULL == current_field_selector) ERROR;

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

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  /* If not found, these pointers will all be set to NULL!! */

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  search_var_instance_decl_c search_decl(symbol);

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  current_type_id       = search_decl.get_decl(current_field_selector);

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  current_basetype_decl = search_base_type.get_basetype_decl(current_type_id);

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  current_basetype_id   = search_base_type.get_basetype_id  (current_type_id);

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  return NULL;

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}