/*
* (c) 2003 Mario de Sousa
*
* Offered to the public under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
* Public License for more details.
*
* This code is made available on the understanding that it will not be
* used in safety-critical situations without a full and competent review.
*/
/*
* An IEC 61131-3 IL and ST compiler.
*
* Based on the
* FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)
*
*/
/* Determine the data type of a variable.
* The variable may be a simple variable, a function block instance, a
* struture element within a data structured type (a struct or a fb), or
* an array element.
* A mixture of array element of a structure element of a structure element
* of a .... is also suported!
*
* A reference to the relevant base type __definition__ is returned.
* This means that if we find that the variable is of type MY_INT,
* which was previously declared to be
* TYPE MY_INT: INT := 9;
* this class wil return INT, and __not__ MY_INT !!
*
*
* example:
* window.points[1].coordinate.x
* window.points[1].colour
* etc... ARE ALLOWED!
*
* This class must be passed the scope within which the
* variable was declared, and the variable name...
*/
/*
* TODO: this code has a memory leak...
* We call 'new' in several locations, but bever get to 'delete' the object instances...
*/
#include "absyntax_utils.hh"
search_varfb_instance_type_c::search_varfb_instance_type_c(symbol_c *search_scope): search_var_instance_decl(search_scope) {
this->decompose_var_instance_name = NULL;
this->current_structelement_name = NULL;
this->search_base_type = false;
}
symbol_c *search_varfb_instance_type_c::get_type(symbol_c *variable_name, bool base_type) {
this->current_structelement_name = NULL;
this->decompose_var_instance_name = new decompose_var_instance_name_c(variable_name);
this->search_base_type = base_type;
if (NULL == decompose_var_instance_name) ERROR;
/* find the part of the variable name that will appear in the
* variable declaration, for e.g., in window.point.x, this would be
* window!
*/
symbol_c *var_name_part = decompose_var_instance_name->next_part();
if (NULL == var_name_part) ERROR;
/* Now we try to find the variable instance declaration, to determine its type... */
symbol_c *var_decl = search_var_instance_decl.get_decl(var_name_part);
if (NULL == var_decl) {
/* variable instance declaration not found! */
ERROR;
}
/* if it is a struct or function block, we must search the type
* of the struct or function block member.
* This is done by this class visiting the var_decl.
* This class, while visiting, will recursively call
* decompose_var_instance_name->get_next() when and if required...
*/
symbol_c *res = (symbol_c *)var_decl->accept(*this);
if (NULL == res) ERROR;
/* make sure that we have decomposed all strcuture elements of the variable name */
symbol_c *var_name = decompose_var_instance_name->next_part();
if (NULL != var_name) ERROR;
return res;
}
unsigned int search_varfb_instance_type_c::get_vartype(symbol_c *variable_name) {
this->current_structelement_name = NULL;
this->decompose_var_instance_name = new decompose_var_instance_name_c(variable_name);
if (NULL == decompose_var_instance_name) ERROR;
/* find the part of the variable name that will appear in the
* variable declaration, for e.g., in window.point.x, this would be
* window!
*/
symbol_c *var_name_part = decompose_var_instance_name->next_part();
if (NULL == var_name_part) ERROR;
/* Now we try to find the variable instance declaration, to determine its type... */
symbol_c *var_decl = search_var_instance_decl.get_decl(var_name_part);
if (NULL == var_decl) {
/* variable instance declaration not found! */
return 0;
}
/* if it is a struct or function block, we must search the type
* of the struct or function block member.
* This is done by this class visiting the var_decl.
* This class, while visiting, will recursively call
* decompose_var_instance_name->get_next() when and if required...
*/
unsigned int res = search_var_instance_decl.get_vartype();
/* make sure that we have decomposed all strcuture elements of the variable name */
symbol_c *var_name = decompose_var_instance_name->next_part();
if (NULL != var_name) ERROR;
return res;
}
/* a helper function... */
void *search_varfb_instance_type_c::visit_list(list_c *list) {
if (NULL == current_structelement_name) ERROR;
for(int i = 0; i < list->n; i++) {
void *res = list->elements[i]->accept(*this);
if (res != NULL)
return res;
}
/* not found! */
return NULL;
}
/* a helper function... */
void *search_varfb_instance_type_c::base_type(symbol_c *symbol) {
search_base_type_c search_base_type;
return symbol->accept(search_base_type);
}
/* We override the base class' visitor to identifier_c.
* This is so because the base class does not consider a function block
* to be a type, unlike this class that allows a variable instance
* of a function block type...
*/
void *search_varfb_instance_type_c::visit(identifier_c *type_name) {
/* look up the type declaration... */
symbol_c *fb_decl = function_block_type_symtable.find_value(type_name);
if (fb_decl != function_block_type_symtable.end_value())
/* Type declaration found!! */
return fb_decl->accept(*this);
/* No. It is not a function block, so we let
* the base class take care of it...
*/
if (this->search_base_type)
return search_base_type_c::visit(type_name);
else
return type_name;
}
/********************************/
/* B 1.3.3 - Derived data types */
/********************************/
/* identifier ':' array_spec_init */
void *search_varfb_instance_type_c::visit(array_type_declaration_c *symbol) {
return symbol->array_spec_init->accept(*this);
}
/* array_specification [ASSIGN array_initialization} */
/* array_initialization may be NULL ! */
void *search_varfb_instance_type_c::visit(array_spec_init_c *symbol) {
symbol_c *var_name = decompose_var_instance_name->next_part();
if (NULL != var_name)
current_structelement_name = var_name;
return symbol->array_specification->accept(*this);
}
/* ARRAY '[' array_subrange_list ']' OF non_generic_type_name */
void *search_varfb_instance_type_c::visit(array_specification_c *symbol) {
symbol_c *var_name = decompose_var_instance_name->next_part();
if (NULL != var_name)
current_structelement_name = var_name;
return symbol->non_generic_type_name->accept(*this);
}
/* structure_type_name ':' structure_specification */
void *search_varfb_instance_type_c::visit(structure_type_declaration_c *symbol) {
return symbol->structure_specification->accept(*this);
/* NOTE: structure_specification will point to either a
* initialized_structure_c
* OR A
* structure_element_declaration_list_c
*/
}
/* structure_type_name ASSIGN structure_initialization */
/* structure_initialization may be NULL ! */
// SYM_REF2(initialized_structure_c, structure_type_name, structure_initialization)
void *search_varfb_instance_type_c::visit(initialized_structure_c *symbol) {
/* make sure that we have decomposed all strcuture elements of the variable name */
symbol_c *var_name = decompose_var_instance_name->next_part();
if (NULL == var_name) {
/* this is it... !
* No need to look any further...
*/
/* NOTE: we could simply do a
* return (void *)symbol;
* nevertheless, note that this search_varfb_instance_type_c
* class inherits from the search_base_type_c class,
* which means that it will usually return the base type,
* and not the derived type (*). If we are to be consistent,
* we should guarantee that we always return the base type.
* To do this we could use
* return (void *)symbol->accept(*this);
* since this class inherits from the search_base_type_c.
* However, in this case we don't want it to follow
* the structs as this search_varfb_instance_type_c does.
* We therefore have to create a new search_base_type_c
* instance to search through this type without going
* through the structs...
*/
return base_type(symbol->structure_type_name);
}
/* now search the structure declaration */
current_structelement_name = var_name;
/* recursively find out the data type of var_name... */
return symbol->structure_type_name->accept(*this);
}
/* helper symbol for structure_declaration */
/* structure_declaration: STRUCT structure_element_declaration_list END_STRUCT */
/* structure_element_declaration_list structure_element_declaration ';' */
void *search_varfb_instance_type_c::visit(structure_element_declaration_list_c *symbol) {
return visit_list(symbol);
}
/* structure_element_name ':' spec_init */
void *search_varfb_instance_type_c::visit(structure_element_declaration_c *symbol) {
if (NULL == current_structelement_name) ERROR;
if (compare_identifiers(symbol->structure_element_name, current_structelement_name) == 0)
return symbol->spec_init->accept(*this);
return NULL;
}
/* helper symbol for structure_initialization */
/* structure_initialization: '(' structure_element_initialization_list ')' */
/* structure_element_initialization_list ',' structure_element_initialization */
void *search_varfb_instance_type_c::visit(structure_element_initialization_list_c *symbol) {ERROR; return NULL;} /* should never get called... */
/* structure_element_name ASSIGN value */
void *search_varfb_instance_type_c::visit(structure_element_initialization_c *symbol) {ERROR; return NULL;} /* should never get called... */
/**************************************/
/* B.1.5 - Program organization units */
/**************************************/
/*****************************/
/* B 1.5.2 - Function Blocks */
/*****************************/
/* FUNCTION_BLOCK derived_function_block_name io_OR_other_var_declarations function_block_body END_FUNCTION_BLOCK */
// SYM_REF4(function_block_declaration_c, fblock_name, var_declarations, fblock_body, unused)
void *search_varfb_instance_type_c::visit(function_block_declaration_c *symbol) {
/* make sure that we have decomposed all strcuture elements of the variable name */
symbol_c *var_name = decompose_var_instance_name->next_part();
if (NULL == var_name) {
/* this is it... !
* No need to look any further...
* Note also that, unlike for the struct types, a function block may
* not be defined based on another (i.e. no inheritance is allowed),
* so this function block is already the most base type.
* We simply return it.
*/
return (void *)symbol;
}
/* now search the function block declaration for the variable... */
search_var_instance_decl_c search_decl(symbol);
symbol_c *var_decl = search_decl.get_decl(var_name);
if (NULL == var_decl) {
/* variable instance declaration not found! */
return NULL;
}
/* We have found the declaration.
* Should we look any further?
*/
var_name = decompose_var_instance_name->next_part();
if (NULL == var_name) {
/* this is it... ! */
return base_type(var_decl);
}
current_structelement_name = var_name;
/* recursively find out the data type of var_name... */
return symbol->var_declarations->accept(*this);
}