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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) 2003-2011  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_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 them, we don't yet implement

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 *   get_basetype_id()    ----> would return 2A

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 *   get_type_decl()      ----> would return 1B

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 */ 

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/*

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 * TODO: this code has a memory leak...

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 *       We call 'new' in several locations, but bever get to 'delete' the object instances...

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 */

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#include "absyntax_utils.hh"

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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->decompose_var_instance_name = NULL;

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  this->current_structelement_name = NULL;

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  this->current_typeid = NULL;

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  this->current_structelement_name = NULL;

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  this->current_typeid = 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 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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  /* NOTE: A Null result is not really an internal compiler error, but rather an error in 

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   * the IEC 61131-3 source code being compiled. This means we cannot just abort the compiler with ERROR.

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   * //   if (NULL == res) ERROR;

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   */

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  if (NULL == res) return NULL;

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

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  symbol_c *var_name = decompose_var_instance_name->next_part();

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  /* NOTE: A non-NULL result is not really an internal compiler error, but rather an error in 

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   * the IEC 61131-3 source code being compiled. 

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   *  (for example, 'int_var.struct_elem' in the source code, when 'int_var' is a simple integer,

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   *   and not a structure, will result in this result being non-NULL!)

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   * This means we cannot just abort the compiler with ERROR.

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   * //   if (NULL != var_name) ERROR;

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   */

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  if (NULL != var_name) return NULL;

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  return res;

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}

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unsigned int search_varfb_instance_type_c::get_vartype(symbol_c *variable_name) {

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  this->current_structelement_name = NULL;

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  this->current_typeid = NULL;

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  this->is_complex = false;

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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 0;

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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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  var_decl->accept(*this);

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  unsigned int res = search_var_instance_decl.get_vartype();

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  /* make sure that we have decomposed all structure 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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symbol_c *search_varfb_instance_type_c::get_type_id(symbol_c *variable_name) {

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  this->current_typeid = NULL;

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  if (this->current_typeid != NULL)

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    return this->current_typeid;

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  else

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    return vartype;

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}

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bool search_varfb_instance_type_c::type_is_complex(void) {

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  return this->is_complex;

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}

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/* a helper function... */

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void *search_varfb_instance_type_c::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 *search_varfb_instance_type_c::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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/* 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 *search_varfb_instance_type_c::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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/*  identifier ':' array_spec_init */

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

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  this->is_complex = true;

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

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

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  this->is_complex = true;

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

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}

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

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

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  this->is_complex = true;

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

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

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  this->is_complex = true;

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  if (NULL == current_structelement_name) ERROR;

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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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/* NOTE: only the initialized structure is ever used when declaring a new variable instance */

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

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  this->is_complex = true;

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  if (NULL != current_structelement_name) 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) {

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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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  /* look for the var_name in the structure declaration */

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  current_structelement_name = var_name;

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  /* recursively find out the data type of current_structelement_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 *search_varfb_instance_type_c::visit(structure_element_declaration_list_c *symbol)	{

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  if (NULL == current_structelement_name) ERROR;

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  /* now search the structure declaration */

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  return visit_list(symbol);

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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_structelement_name) ERROR;

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

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    current_structelement_name = NULL;

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

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

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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.1.5 - 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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  /* 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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#if 0

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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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#endif  

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  /* carry on recursively, in case the variable has more elements to be decomposed... */

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  return var_decl->accept(*this);

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}