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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) 2009-2012  Mario de Sousa (msousa@fe.up.pt)

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 *  Copyright (C) 2012       Manuele Conti  (conti.ma@alice.it)

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 *

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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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 */

    25

    26

/*

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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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/* Expressions on the left hand side of assignment statements have aditional restrictions on their datatype.

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 * For example, they cannot be literals, CONSTANT type variables, function invocations, etc...

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 * This class wil do those checks.

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 * 

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 * Note that assignment may also be done when passing variables to OUTPUT or IN_OUT function parameters,so we check those too.

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 */

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#include "lvalue_check.hh"

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#define FIRST_(symbol1, symbol2) (((symbol1)->first_order < (symbol2)->first_order)   ? (symbol1) : (symbol2))

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#define  LAST_(symbol1, symbol2) (((symbol1)->last_order  > (symbol2)->last_order)    ? (symbol1) : (symbol2))

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#define STAGE3_ERROR(error_level, symbol1, symbol2, ...) {                                                                  \

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  if (current_display_error_level >= error_level) {                                                                         \

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    fprintf(stderr, "%s:%d-%d..%d-%d: error: ",                                                                             \

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            FIRST_(symbol1,symbol2)->first_file, FIRST_(symbol1,symbol2)->first_line, FIRST_(symbol1,symbol2)->first_column,\

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                                                 LAST_(symbol1,symbol2) ->last_line,  LAST_(symbol1,symbol2) ->last_column);\

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    fprintf(stderr, __VA_ARGS__);                                                                                           \

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    fprintf(stderr, "\n");                                                                                                  \

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    error_count++;                                                                                                     \

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  }                                                                                                                         \

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}

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    61

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#define STAGE3_WARNING(symbol1, symbol2, ...) {                                                                             \

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    fprintf(stderr, "%s:%d-%d..%d-%d: warning: ",                                                                           \

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            FIRST_(symbol1,symbol2)->first_file, FIRST_(symbol1,symbol2)->first_line, FIRST_(symbol1,symbol2)->first_column,\

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                                                 LAST_(symbol1,symbol2) ->last_line,  LAST_(symbol1,symbol2) ->last_column);\

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    fprintf(stderr, __VA_ARGS__);                                                                                           \

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    fprintf(stderr, "\n");                                                                                                  \

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    warning_found = true;                                                                                                   \

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}

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lvalue_check_c::lvalue_check_c(symbol_c *ignore) {

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	error_count = 0;

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	current_display_error_level = 0;

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	current_il_operand = NULL;

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	search_varfb_instance_type = NULL;

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	search_var_instance_decl = NULL;

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}

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lvalue_check_c::~lvalue_check_c(void) {

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}

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int lvalue_check_c::get_error_count() {

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	return error_count;

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}

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#include <strings.h>

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/* No writing to iterator variables (used in FOR loops) inside the loop itself */

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void lvalue_check_c::check_assignment_to_controlvar(symbol_c *lvalue) {

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	for (unsigned int i = 0; i < control_variables.size(); i++) {

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		token_c *lvalue_name = get_var_name_c::get_name(lvalue);

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		if (compare_identifiers(lvalue_name, control_variables[i]) == 0) {

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			STAGE3_ERROR(0, lvalue, lvalue, "Assignment to FOR control variable is not allowed.");

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			break;

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		}

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	}

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}

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/* fb_instance.var := ...  is not valid if var is output variable */

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/* NOTE, if a fb_instance1.fb_instance2.fb_instance3.var is used, we must iteratively check that none of the 

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 *       FB records are declared as OUTPUT variables!!  

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 *       This is the reason why we have the while() loop in this function!

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 * 

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 *       Note, however, that the first record (fb_instance1 in the above example) may be an output variable!

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 */

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void lvalue_check_c::check_assignment_to_output(symbol_c *lvalue) {

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	decompose_var_instance_name_c decompose_lvalue(lvalue);

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	/* Get the first element/record of the potentially structured variable symbol */

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	/* Note that if symbol is pointing to an expression (or simply a literal value), it will return a NULL.

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	 * Once we have implemented the check_assignment_to_expression() method, and abort calling the other checks (including this one)

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	 * when an expression is found, we may replace this check with an assertion...

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	 * if (NULL == struct_elem) ERROR;

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	 */

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	symbol_c *struct_elem = decompose_lvalue.get_next();

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	if (NULL == struct_elem) return;

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	symbol_c *type_decl   = search_var_instance_decl->get_decl(struct_elem);

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	// symbol_c *type_id  = spec_init_sperator_c::get_spec(type_decl); /* this is not required! search_base_type_c can handle spec_init symbols! */

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	symbol_c *basetype_id = search_base_type_c::get_basetype_id(/*type_id*/ type_decl);

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	/* If we can not determine the data type of the element, then the code must have a data type semantic error.

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	 * This will have been caught by the data type semantic verifier, so we do not bother with this anymore!

   125

	 */

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	if (NULL == basetype_id) return;

   127

   128

	/* Determine if the record/structure element is of a FB type. */

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	/* NOTE: If the structure element is not a FB type, then we can quit this check.

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	 *       Remember that the standard does not allow a STRUCT data type to have elements that are FB instances!

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	 *       Similarly, arrays of FB instances is also not allowed.

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	 *       So, as soon as we find one record/structure element that is not a FB, no other record/structure element

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	 *       will be of FB type, which means we can quit this check!

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	 */

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	function_block_declaration_c *fb_decl = function_block_type_symtable.find_value(basetype_id);

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	if (function_block_type_symtable.end_value() == fb_decl) return;

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   138

	while (NULL != (struct_elem = decompose_lvalue.get_next())) {

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		search_var_instance_decl_c   fb_search_var_instance_decl(fb_decl);

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		if (search_var_instance_decl_c::output_vt == fb_search_var_instance_decl.get_vartype(struct_elem)) {

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			STAGE3_ERROR(0, struct_elem, struct_elem, "Assignment to FB output variable is not allowed.");

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			return; /* no need to carry on checking once the first error is found! */

   143

		}

   144

   145

		/* prepare for any possible further record/structure elements */

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		type_decl   = fb_search_var_instance_decl.get_decl(struct_elem);

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		basetype_id = search_base_type_c::get_basetype_id(type_decl);

   148

		if (NULL == basetype_id) return; /* same comment as above... */

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		fb_decl = function_block_type_symtable.find_value(basetype_id);

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		if (function_block_type_symtable.end_value() == fb_decl) return; /* same comment as above... */

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	}

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}

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/*  No writing to CONSTANTs */

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void lvalue_check_c::check_assignment_to_constant(symbol_c *lvalue) {

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	unsigned int option = search_var_instance_decl->get_option(lvalue);

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	if (option == search_var_instance_decl_c::constant_opt) {

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		STAGE3_ERROR(0, lvalue, lvalue, "Assignment to CONSTANT variables is not allowed.");

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	}

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}

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/*  No assigning values to expressions. */

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void lvalue_check_c::check_assignment_to_expression(symbol_c *lvalue) {

   166

	/* This may occur in function invocations, when passing values (possibly an expression) to one

   167

	 * of the function's OUTPUT or IN_OUT parameters.

   168

	 */

   169

	if ( 

   170

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

   171

	     /* B 1.2 - Constants */

   172

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

   173

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

   174

	     /* B 1.2.XX - Reference Literals */

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

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	     (typeid( *lvalue ) == typeid( ref_value_null_literal_c       )) || /* defined in IEC 61131-3 v3 - Basically the 'NULL' keyword! */

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

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	     /* B 1.2.1 - Numeric Literals */

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

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	     (typeid( *lvalue ) == typeid( real_c                         )) ||

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	     (typeid( *lvalue ) == typeid( integer_c                      )) ||

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	     (typeid( *lvalue ) == typeid( binary_integer_c               )) ||

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	     (typeid( *lvalue ) == typeid( octal_integer_c                )) ||

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	     (typeid( *lvalue ) == typeid( hex_integer_c                  )) ||

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	     (typeid( *lvalue ) == typeid( neg_real_c                     )) ||

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	     (typeid( *lvalue ) == typeid( neg_integer_c                  )) ||

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	     (typeid( *lvalue ) == typeid( integer_literal_c              )) ||

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	     (typeid( *lvalue ) == typeid( real_literal_c                 )) ||

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	     (typeid( *lvalue ) == typeid( bit_string_literal_c           )) ||

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	     (typeid( *lvalue ) == typeid( boolean_literal_c              )) ||

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	     (typeid( *lvalue ) == typeid( boolean_true_c                 )) || /* should not really be needed */

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	     (typeid( *lvalue ) == typeid( boolean_false_c                )) || /* should not really be needed */

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

   194

	     /* B.1.2.2   Character Strings */

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

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	     (typeid( *lvalue ) == typeid( double_byte_character_string_c )) ||

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	     (typeid( *lvalue ) == typeid( single_byte_character_string_c )) ||

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

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	     /* B 1.2.3 - Time Literals */

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

   201

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

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	     /* B 1.2.3.1 - Duration */

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

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	     (typeid( *lvalue ) == typeid( duration_c                     )) ||

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

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	     /* B 1.2.3.2 - Time of day and Date */

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

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	     (typeid( *lvalue ) == typeid( time_of_day_c                  )) ||

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	     (typeid( *lvalue ) == typeid( daytime_c                      )) || /* should not really be needed */

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	     (typeid( *lvalue ) == typeid( date_c                         )) || /* should not really be needed */

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	     (typeid( *lvalue ) == typeid( date_literal_c                 )) ||

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	     (typeid( *lvalue ) == typeid( date_and_time_c                )) ||

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

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	     /* B.3 - Language ST (Structured Text) */

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

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

   217

	     /* B 3.1 - Expressions */

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

   219

	     (typeid( *lvalue ) == typeid( ref_expression_c               )) || /* an extension to the IEC 61131-3 standard - based on the IEC 61131-3 v3 standard. Returns address of the variable! */

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	     (typeid( *lvalue ) == typeid( or_expression_c                )) ||

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	     (typeid( *lvalue ) == typeid( xor_expression_c               )) ||

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	     (typeid( *lvalue ) == typeid( and_expression_c               )) ||

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	     (typeid( *lvalue ) == typeid( equ_expression_c               )) ||

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	     (typeid( *lvalue ) == typeid( notequ_expression_c            )) ||

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	     (typeid( *lvalue ) == typeid( lt_expression_c                )) ||

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	     (typeid( *lvalue ) == typeid( gt_expression_c                )) ||

   227

	     (typeid( *lvalue ) == typeid( le_expression_c                )) ||

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	     (typeid( *lvalue ) == typeid( ge_expression_c                )) ||

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	     (typeid( *lvalue ) == typeid( add_expression_c               )) ||

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	     (typeid( *lvalue ) == typeid( sub_expression_c               )) ||

   231

	     (typeid( *lvalue ) == typeid( mul_expression_c               )) ||

   232

	     (typeid( *lvalue ) == typeid( div_expression_c               )) ||

   233

	     (typeid( *lvalue ) == typeid( mod_expression_c               )) ||

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	     (typeid( *lvalue ) == typeid( power_expression_c             )) ||

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	     (typeid( *lvalue ) == typeid( neg_expression_c               )) ||

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	     (typeid( *lvalue ) == typeid( not_expression_c               )) ||

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	     (typeid( *lvalue ) == typeid( function_invocation_c          )))

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		STAGE3_ERROR(0, lvalue, lvalue, "Assignment to an expression or a literal value is not allowed.");

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}                                                                  

   240

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/*  No assigning values to IL lists. */

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void lvalue_check_c::check_assignment_to_il_list(symbol_c *lvalue) {

   245

	/* This may occur in formal invocations in IL, where an embedded IL list may be used instead of a symbolic_variable

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	 * when passing an IN_OUT parameter! Note that it will never occur to OUT parameters, as the syntax does not allow it,

   247

	 * although this does not affect out algorithm here!

   248

	 */

   249

	if ( 

   250

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

   251

	     /* B.2 - Language IL (Instruction List) */

   252

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

   253

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

   254

	     /* B 2.1 Instructions and Operands */

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

   256

	     (typeid( *lvalue ) == typeid( simple_instr_list_c)))

   257

		STAGE3_ERROR(0, lvalue, lvalue, "Assigning an IL list to an IN_OUT parameter is not allowed.");

   258

}                                                                  

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void lvalue_check_c::verify_is_lvalue(symbol_c *lvalue) {

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	if (NULL == lvalue) return; // missing operand in source code being compiled. Error will be caught and reported by datatype checking!

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	int init_error_count = error_count;  /* stop the checks once an error has been found... */

   266

	if (error_count == init_error_count)  check_assignment_to_expression(lvalue);

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	if (error_count == init_error_count)  check_assignment_to_il_list   (lvalue);

   268

	if (error_count == init_error_count)  check_assignment_to_controlvar(lvalue);

   269

	if (error_count == init_error_count)  check_assignment_to_output    (lvalue);

   270

	if (error_count == init_error_count)  check_assignment_to_constant  (lvalue);

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}

   272

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/* check whether all values passed to OUT or IN_OUT parameters are legal lvalues. */

   277

/*

   278

 * All parameters being passed to the called function MUST be in the parameter list to which f_call points to!

   279

 * This means that, for non formal function calls in IL, de current (default value) must be artificially added to the

   280

 * beginning of the parameter list BEFORE calling handle_function_call().

   281

 */

   282

#include <string.h> /* required for strcmp() */

   283

void lvalue_check_c::check_nonformal_call(symbol_c *f_call, symbol_c *f_decl) {

   284

	/* if data type semantic verification was unable to determine which function is being called,

   285

	 * then it does not make sense to go ahead and check for lvalues to unknown parameters.

   286

	 * We simply bug out!

   287

	 */

   288

	if (NULL == f_decl) return;

   289

   290

	symbol_c *call_param_value;

   291

	identifier_c *param_name;

   292

	function_param_iterator_c       fp_iterator(f_decl);

   293

	function_call_param_iterator_c fcp_iterator(f_call);

   294

   295

	/* Iterating through the non-formal parameters of the function call */

   296

	while((call_param_value = fcp_iterator.next_nf()) != NULL) {

   297

		/* Iterate to the next parameter of the function being called.

   298

		 * Get the name of that parameter, and ignore if EN or ENO.

   299

		 */

   300

		do {

   301

			param_name = fp_iterator.next();

   302

			/* If there is no other parameter declared, then we are passing too many parameters... */

   303

			/* This error should have been caught in data type verification, so we simply abandon our check! */

   304

			if(param_name == NULL) return;

   305

		} while ((strcmp(param_name->value, "EN") == 0) || (strcmp(param_name->value, "ENO") == 0));

   306

   307

		/* Determine the direction (IN, OUT, IN_OUT) of the parameter... */

   308

		function_param_iterator_c::param_direction_t param_direction = fp_iterator.param_direction();

   309

   310

		/* We only process the parameter value if the paramater itself is valid... */

   311

		if (param_name != NULL) {

   312

			/* If the parameter is either OUT or IN_OUT, we check if 'call_param_value' is a valid lvalue */

   313

			if ((function_param_iterator_c::direction_out == param_direction) || (function_param_iterator_c::direction_inout == param_direction)) 

   314

				verify_is_lvalue(call_param_value);

   315

			/* parameter values to IN  parameters may be expressions with function invocations that must also be checked! */

   316

			/* parameter values to OUT or IN_OUT parameters may contain arrays, whose subscripts contain expressions that must be checked! */

   317

			call_param_value->accept(*this);  

   318

		}

   319

	}

   320

}

   321

   322

   323

   324

   325

   326

   327

/* check whether all values passed to OUT or IN_OUT parameters are legal lvalues. */

   328

void lvalue_check_c::check_formal_call(symbol_c *f_call, symbol_c *f_decl) {

   329

	/* if data type semantic verification was unable to determine which function is being called,

   330

	 * then it does not make sense to go ahead and check for lvalues to unknown parameters.

   331

	 * We simply bug out!

   332

	 */

   333

	if (NULL == f_decl) return;

   334

   335

	symbol_c *call_param_name;

   336

	function_param_iterator_c       fp_iterator(f_decl);

   337

	function_call_param_iterator_c fcp_iterator(f_call);

   338

   339

	/* Iterating through the formal parameters of the function call */

   340

	while((call_param_name = fcp_iterator.next_f()) != NULL) {

   341

   342

		/* Obtaining the value being passed in the function call */

   343

		symbol_c *call_param_value = fcp_iterator.get_current_value();

   344

		if (NULL == call_param_value) ERROR;

   345

   346

		/* Find the corresponding parameter in function declaration, and it's direction (IN, OUT, IN_OUT) */

   347

		identifier_c *param_name = fp_iterator.search(call_param_name);

   348

		function_param_iterator_c::param_direction_t param_direction = fp_iterator.param_direction();

   349

   350

		/* We only process the parameter value if the paramater itself is valid... */

   351

		if (param_name != NULL) {

   352

			/* If the parameter is either OUT or IN_OUT, we check if 'call_param_value' is a valid lvalue */

   353

			if ((function_param_iterator_c::direction_out == param_direction) || (function_param_iterator_c::direction_inout == param_direction)) 

   354

				verify_is_lvalue(call_param_value);

   355

			/* parameter values to IN  parameters may be expressions with function invocations that must also be checked! */

   356

			/* parameter values to OUT or IN_OUT parameters may contain arrays, whose subscripts contain expressions that must be checked! */

   357

			call_param_value->accept(*this);  

   358

 		}

   359

	}

   360

}

   361

   362

   363

   364

   365

   366

   367

   368

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

   369

/* B 1.5 - Program organisation units */

   370

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

   371

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

   372

/* B 1.5.1 - Functions */

   373

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

   374

void *lvalue_check_c::visit(function_declaration_c *symbol) {

   375

	search_varfb_instance_type = new search_varfb_instance_type_c(symbol);

   376

	search_var_instance_decl = new search_var_instance_decl_c(symbol);

   377

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

   378

	delete search_varfb_instance_type;

   379

	delete search_var_instance_decl;

   380

	search_varfb_instance_type = NULL;

   381

	search_var_instance_decl = NULL;

   382

	return NULL;

   383

}

   384

   385

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

   386

/* B 1.5.2 - Function blocks */

   387

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

   388

void *lvalue_check_c::visit(function_block_declaration_c *symbol) {

   389

	search_varfb_instance_type = new search_varfb_instance_type_c(symbol);

   390

	search_var_instance_decl = new search_var_instance_decl_c(symbol);

   391

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

   392

	delete search_varfb_instance_type;

   393

	delete search_var_instance_decl;

   394

	search_varfb_instance_type = NULL;

   395

	search_var_instance_decl = NULL;

   396

	return NULL;

   397

}

   398

   399

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

   400

/* B 1.5.3 - Programs */

   401

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

   402

void *lvalue_check_c::visit(program_declaration_c *symbol) {

   403

	search_varfb_instance_type = new search_varfb_instance_type_c(symbol);

   404

	search_var_instance_decl = new search_var_instance_decl_c(symbol);

   405

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

   406

	delete search_varfb_instance_type;

   407

	delete search_var_instance_decl;

   408

	search_varfb_instance_type = NULL;

   409

	search_var_instance_decl = NULL;

   410

	return NULL;

   411

}

   412

   413

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

   414

/* B.2 - Language IL (Instruction List) */

   415

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

   416

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

   417

/* B 2.1 Instructions and Operands */

   418

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

   419

void *lvalue_check_c::visit(il_instruction_c *symbol) {

   420

	/* il_instruction will be NULL when parsing a label with no instruction

   421

	 * e.g.:   label1:          <---- il_instruction = NULL!

   422

	 *                 LD 33

   423

	 *                 ...

   424

	 */

   425

	if (NULL != symbol->il_instruction)

   426

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

   427

	return NULL;

   428

}

   429

   430

void *lvalue_check_c::visit(il_simple_operation_c *symbol) {

   431

	current_il_operand = symbol->il_operand;

   432

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

   433

	current_il_operand = NULL;

   434

	return NULL;

   435

}

   436

   437

   438

   439

   440

/* | function_name [il_operand_list] */

   441

/* NOTE: The parameters 'called_function_declaration' and 'extensible_param_count' are used to pass data between the stage 3 and stage 4. */

   442

// SYM_REF2(il_function_call_c, function_name, il_operand_list, symbol_c *called_function_declaration; int extensible_param_count;)

   443

void *lvalue_check_c::visit(il_function_call_c *symbol) {

   444

	/* The first parameter of a non formal function call in IL will be the 'current value' (i.e. the prev_il_instruction)

   445

	 * In order to be able to handle this without coding special cases, we will simply prepend that symbol

   446

	 * to the il_operand_list, and remove it after calling handle_function_call().

   447

	 *

   448

	 * However, if no further paramters are given, then il_operand_list will be NULL, and we will

   449

	 * need to create a new object to hold the pointer to prev_il_instruction.

   450

	 * This change will also be undone at the end of this method.

   451

	 */

   452

	/* TODO: Copying the location data will result in confusing error message. 

   453

	 *       We need to make this better, by inserting code to handle this special situation explicitly!

   454

	 */

   455

	/* NOTE: When calling a function, using the 'current value' as the first parameter of the function invocation

   456

	 *       implies that we can only call functions whose first parameter is IN. It would not do to pass

   457

	 *       the 'current value' to an OUT or IN_OUT parameter.

   458

	 *       In order to make sure that this will be caught by the check_nonformal_call() function,

   459

	 *       we add a symbol that cannot be an lvalue; in this case, a real_c (REAL literal).

   460

	 */

   461

	real_c param_value(NULL);

   462

	*((symbol_c *)(&param_value)) = *((symbol_c *)symbol); /* copy the symbol location (file, line, offset) data */

   463

	if (NULL == symbol->il_operand_list)  symbol->il_operand_list = new il_operand_list_c;

   464

	if (NULL == symbol->il_operand_list)  ERROR;

   465

	((list_c *)symbol->il_operand_list)->insert_element(&param_value, 0);

   466

   467

	check_nonformal_call(symbol, symbol->called_function_declaration);

   468

   469

	/* Undo the changes to the abstract syntax tree we made above... */

   470

	((list_c *)symbol->il_operand_list)->remove_element(0);

   471

	if (((list_c *)symbol->il_operand_list)->n == 0) {

   472

		/* if the list becomes empty, then that means that it did not exist before we made these changes, so we delete it! */

   473

		delete 	symbol->il_operand_list;

   474

		symbol->il_operand_list = NULL;

   475

	}

   476

   477

	return NULL;

   478

}

   479

   480

   481

   482

   483

   484

   485

/*   il_call_operator prev_declared_fb_name

   486

 * | il_call_operator prev_declared_fb_name '(' ')'

   487

 * | il_call_operator prev_declared_fb_name '(' eol_list ')'

   488

 * | il_call_operator prev_declared_fb_name '(' il_operand_list ')'

   489

 * | il_call_operator prev_declared_fb_name '(' eol_list il_param_list ')'

   490

 */

   491

/* NOTE: The parameter 'called_fb_declaration'is used to pass data between stage 3 and stage4 (although currently it is not used in stage 4 */

   492

// SYM_REF4(il_fb_call_c, il_call_operator, fb_name, il_operand_list, il_param_list, symbol_c *called_fb_declaration)

   493

void *lvalue_check_c::visit(il_fb_call_c *symbol) {

   494

	if (NULL != symbol->il_operand_list)  check_nonformal_call(symbol, symbol->called_fb_declaration);

   495

	if (NULL != symbol->  il_param_list)     check_formal_call(symbol, symbol->called_fb_declaration);

   496

	return NULL;

   497

}

   498

   499