Remove potential access to NULL pointer.
/*
* matiec - a compiler for the programming languages defined in IEC 61131-3
*
* Copyright (C) 2009-2012 Mario de Sousa (msousa@fe.up.pt)
* Copyright (C) 2012 Manuele Conti (conti.ma@alice.it)
*
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 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.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*
* 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 compiler.
*
* Based on the
* FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)
*
*/
#include <vector>
#include "../absyntax_utils/absyntax_utils.hh"
#include "datatype_functions.hh"
/* Expressions on the left hand side of assignment statements have aditional restrictions on their datatype.
* For example, they cannot be literals, CONSTANT type variables, function invocations, etc...
* This class wil do those checks.
*
* Note that assignment may also be done when passing variables to OUTPUT or IN_OUT function parameters,so we check those too.
*/
class lvalue_check_c: public iterator_visitor_c {
private:
search_varfb_instance_type_c *search_varfb_instance_type;
search_var_instance_decl_c *search_var_instance_decl;
search_base_type_c search_base_type;
int error_count;
int current_display_error_level;
std::vector <token_c *> control_variables;
symbol_c *current_il_operand;
void verify_is_lvalue (symbol_c *lvalue);
void check_assignment_to_controlvar(symbol_c *lvalue);
void check_assignment_to_output (symbol_c *lvalue);
void check_assignment_to_constant (symbol_c *lvalue);
void check_assignment_to_expression(symbol_c *lvalue);
void check_formal_call (symbol_c *f_call, symbol_c *f_decl);
void check_nonformal_call(symbol_c *f_call, symbol_c *f_decl);
public:
lvalue_check_c(symbol_c *ignore);
virtual ~lvalue_check_c(void);
int get_error_count();
/**************************************/
/* B 1.5 - Program organisation units */
/**************************************/
/***********************/
/* B 1.5.1 - Functions */
/***********************/
void *visit(function_declaration_c *symbol);
/*****************************/
/* B 1.5.2 - Function blocks */
/*****************************/
void *visit(function_block_declaration_c *symbol);
/**********************/
/* B 1.5.3 - Programs */
/**********************/
void *visit(program_declaration_c *symbol);
/****************************************/
/* B.2 - Language IL (Instruction List) */
/****************************************/
/***********************************/
/* B 2.1 Instructions and Operands */
/***********************************/
void *visit(il_instruction_c *symbol);
void *visit(il_simple_operation_c *symbol);
void *visit(il_function_call_c *symbol);
void *visit(il_fb_call_c *symbol);
void *visit(il_formal_funct_call_c *symbol);
/*******************/
/* B 2.2 Operators */
/*******************/
void *visit(ST_operator_c *symbol);
void *visit(STN_operator_c *symbol);
void *visit(S_operator_c *symbol);
void *visit(R_operator_c *symbol);
/***************************************/
/* B.3 - Language ST (Structured Text) */
/***************************************/
/***********************/
/* B 3.1 - Expressions */
/***********************/
void *visit(function_invocation_c *symbol);
/*********************************/
/* B 3.2.1 Assignment Statements */
/*********************************/
void *visit(assignment_statement_c *symbol);
/*****************************************/
/* B 3.2.2 Subprogram Control Statements */
/*****************************************/
void *visit(fb_invocation_c *symbol);
/********************************/
/* B 3.2.4 Iteration Statements */
/********************************/
void *visit(for_statement_c *symbol);
}; /* lvalue_check_c */