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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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/* Decomposes a variable instance name into its constituents,
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* example:
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* window.points[1].coordinate.x
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*
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* will succesfully return
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* - window
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* - points
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* - coordinate
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* - x
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* on succesive calls to decompose_var_instance_name_c::next_part()
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*/
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#include "decompose_var_instance_name.hh"
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decompose_var_instance_name_c::decompose_var_instance_name_c(symbol_c *variable_instance_name) {
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variable_name = variable_instance_name;
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next_variable_name = NULL;
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current_recursive_variable_name = NULL;
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previously_returned_variable_name = NULL;
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}
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symbol_c *decompose_var_instance_name_c::next_part(void) {
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/* We must always start from the top!
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* See note in the structured_variable_c visitor
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* to understand why...
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*/
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symbol_c *res = (symbol_c *)variable_name->accept(*this);
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next_variable_name = current_recursive_variable_name;
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if (previously_returned_variable_name == res)
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return NULL;
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previously_returned_variable_name = res;
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return res;
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}
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/*********************/
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/* B 1.4 - Variables */
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/*********************/
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void *decompose_var_instance_name_c::visit(symbolic_variable_c *symbol) {return (void *)(symbol->var_name);}
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/********************************************/
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/* B.1.4.1 Directly Represented Variables */
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/********************************************/
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void *decompose_var_instance_name_c::visit(direct_variable_c *symbol) {return (void *)symbol;}
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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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void *decompose_var_instance_name_c::visit(array_variable_c *symbol) {
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/* NOTE: the subscripted_variable may itself be a structure!,
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* so we must recursevily visit!
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*/
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return symbol->subscripted_variable->accept(*this);
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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 tructured 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 *decompose_var_instance_name_c::visit(structured_variable_c *symbol) {
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/* NOTE: The following code will not work, as structured_variable_c
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* are grouped on the left, and not on the right!
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*
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* example: window.origin.x
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* will result in
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* s1 = structured_variable_c("window, "origin");
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* s2 = structured_variable_c(s1, "x");
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* AND NOT
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* s1 = structured_variable_c("origin", "x");
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* s2 = structured_variable_c("window", s1);
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*
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* as the following code assumes!!
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*
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current_variable_name = symbol->field_selector;
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return symbol->record_variable->accept(*this);
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*/
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/* The correct code, is therefore more complex... */
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if (next_variable_name == symbol) {
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/* NOTE: field_selector is always an identifier_c,
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* so we do not have to recursevily visit it again...
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* return (void *)symbol->field_selector->accept(*this); -> NOT REQUIRED!!
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*/
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return (void *)symbol->field_selector;
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}
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current_recursive_variable_name = symbol;
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return symbol->record_variable->accept(*this);
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}
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