1 /*

     2  *  matiec - a compiler for the programming languages defined in IEC 61131-3

     3  *

     4  *  Copyright (C) 2009-2012  Mario de Sousa (msousa@fe.up.pt)

     5  *  Copyright (C) 2012       Manuele Conti (manuele.conti@sirius-es.it)

     6  *  Copyright (C) 2012       Matteo Facchinetti (matteo.facchinetti@sirius-es.it)

     7  *

     8  *  This program is free software: you can redistribute it and/or modify

     9  *  it under the terms of the GNU General Public License as published by

    10  *  the Free Software Foundation, either version 3 of the License, or

    11  *  (at your option) any later version.

    12  *

    13  *  This program is distributed in the hope that it will be useful,

    14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of

    15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    16  *  GNU General Public License for more details.

    17  *

    18  *  You should have received a copy of the GNU General Public License

    19  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.

    20  *

    21  *

    22  * This code is made available on the understanding that it will not be

    23  * used in safety-critical situations without a full and competent review.

    24  */

    25 

    26 /*

    27  * An IEC 61131-3 compiler.

    28  *

    29  * Based on the

    30  * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)

    31  *

    32  */

    33 

    34 

    35 /* TODO - things yet not checked by this data type checker...

    36  *

    37  * - check variable declarations

    38  * - check data type declarations

    39  * - check inside configurations (variable declarations)

    40  * - check SFC code

    41  * - must fix S and R IL functions (includes potientialy fixing stage4 code!) 

    42  */

    43 

    44 

    45 /* NOTE: The algorithm implemented here assumes that flow control analysis has already been completed!

    46  *       BEFORE running this visitor, be sure to CALL the flow_control_analysis_c visitor!

    47  */

    48 

    49 

    50 /*

    51  *  Fill the candidate datatype list for all symbols that may legally 'have' a data type (e.g. variables, literals, function calls, expressions, etc.)

    52  * 

    53  *  The candidate datatype list will be filled with a list of all the data types that expression may legally take.

    54  *  For example, the very simple literal '0' (as in foo := 0), may represent a:

    55  *    BOOL, BYTE, WORD, DWORD, LWORD, USINT, SINT, UINT, INT, UDINT, DINT, ULINT, LINT (as well as the SAFE versions of these data tyes too!)

    56  */

    57 

    58 #include <../main.hh>         /* required for UINT64_MAX, INT64_MAX, INT64_MIN, ... */

    59 #include "fill_candidate_datatypes.hh"

    60 #include "datatype_functions.hh"

    61 #include <typeinfo>

    62 #include <list>

    63 #include <string>

    64 #include <string.h>

    65 #include <strings.h>

    66 

    67 #define GET_CVALUE(dtype, symbol)             ((symbol)->const_value._##dtype.value)

    68 #define VALID_CVALUE(dtype, symbol)           (symbol_c::cs_const_value == (symbol)->const_value._##dtype.status)

    69 #define IS_OVERFLOW(dtype, symbol)            (symbol_c::cs_overflow == (symbol)->const_value._##dtype.status)

    70 

    71 /* set to 1 to see debug info during execution */

    72 static int debug = 0;

    73 

    74 fill_candidate_datatypes_c::fill_candidate_datatypes_c(symbol_c *ignore) {

    75 }

    76 

    77 fill_candidate_datatypes_c::~fill_candidate_datatypes_c(void) {

    78 }

    79 

    80 symbol_c *fill_candidate_datatypes_c::widening_conversion(symbol_c *left_type, symbol_c *right_type, const struct widen_entry widen_table[]) {

    81 	int k;

    82 	/* find a widening table entry compatible */

    83 	for (k = 0; NULL != widen_table[k].left;  k++)

    84 		if ((typeid(*left_type) == typeid(*widen_table[k].left)) && (typeid(*right_type) == typeid(*widen_table[k].right)))

    85                       return widen_table[k].result;

    86 	return NULL;

    87 }

    88 

    89 

    90 /* add a data type to a candidate data type list, while guaranteeing no duplicate entries! */

    91 /* Returns true if it really did add the datatype to the list, or false if it was already present in the list! */

    92 bool fill_candidate_datatypes_c::add_datatype_to_candidate_list(symbol_c *symbol, symbol_c *datatype) {

    93   /* If it is an invalid data type, do not insert!

    94    * NOTE: it reduces overall code size to do this test here, instead of doing every time before calling the add_datatype_to_candidate_list() function. 

    95    */

    96   if (!is_type_valid(datatype)) /* checks for NULL and invalid_type_name_c */

    97     return false;

    98 

    99   if (search_in_candidate_datatype_list(datatype, symbol->candidate_datatypes) >= 0) 

   100     /* already in the list, Just return! */

   101     return false;

   102   

   103   /* not yet in the candidate data type list, so we insert it now! */

   104   symbol->candidate_datatypes.push_back(datatype);

   105   return true;

   106 }

   107     

   108     

   109 bool fill_candidate_datatypes_c::add_2datatypes_to_candidate_list(symbol_c *symbol, symbol_c *datatype1, symbol_c *datatype2) {

   110   add_datatype_to_candidate_list(symbol, datatype1);

   111   add_datatype_to_candidate_list(symbol, datatype2);

   112   return true;

   113 }

   114 

   115 

   116 

   117 void fill_candidate_datatypes_c::remove_incompatible_datatypes(symbol_c *symbol) {

   118   #ifdef __REMOVE__

   119     #error __REMOVE__ macro already exists. Choose another name!

   120   #endif

   121   #define __REMOVE__(datatype)\

   122       remove_from_candidate_datatype_list(&search_constant_type_c::datatype,       symbol->candidate_datatypes);\

   123       remove_from_candidate_datatype_list(&search_constant_type_c::safe##datatype, symbol->candidate_datatypes);

   124   

   125   {/* Remove unsigned data types */

   126     uint64_t value = 0;

   127     if (VALID_CVALUE( uint64, symbol)) value = GET_CVALUE(uint64, symbol);

   128     if (IS_OVERFLOW ( uint64, symbol)) value = (uint64_t)UINT32_MAX + (uint64_t)1;

   129     

   130     if (value > 1          )          {__REMOVE__(bool_type_name);}

   131     if (value > UINT8_MAX  )          {__REMOVE__(usint_type_name);  __REMOVE__( byte_type_name);}

   132     if (value > UINT16_MAX )          {__REMOVE__( uint_type_name);  __REMOVE__( word_type_name);}

   133     if (value > UINT32_MAX )          {__REMOVE__(udint_type_name);  __REMOVE__(dword_type_name);}

   134     if (IS_OVERFLOW( uint64, symbol)) {__REMOVE__(ulint_type_name);  __REMOVE__(lword_type_name);}

   135   }

   136 

   137   {/* Remove signed data types */

   138     int64_t value = 0;

   139     if (VALID_CVALUE(  int64, symbol)) value = GET_CVALUE(int64, symbol);

   140     if (IS_OVERFLOW (  int64, symbol)) value = (int64_t)INT32_MAX + (int64_t)1;

   141     

   142     if ((value <  INT8_MIN) || (value >  INT8_MAX)) {__REMOVE__(sint_type_name);}

   143     if ((value < INT16_MIN) || (value > INT16_MAX)) {__REMOVE__( int_type_name);}

   144     if ((value < INT32_MIN) || (value > INT32_MAX)) {__REMOVE__(dint_type_name);}

   145     if (IS_OVERFLOW( int64, symbol))                {__REMOVE__(lint_type_name);}

   146   }

   147     

   148   {/* Remove floating point data types */

   149     real64_t value = 0;

   150     if (VALID_CVALUE( real64, symbol)) value = GET_CVALUE(real64, symbol);

   151     if (IS_OVERFLOW ( real64, symbol)) value = (real64_t)REAL32_MAX + (real64_t)1;

   152     if (value >  REAL32_MAX )         {__REMOVE__( real_type_name);}

   153     if (value < -REAL32_MAX )         {__REMOVE__( real_type_name);}

   154     if (IS_OVERFLOW( real64, symbol)) {__REMOVE__(lreal_type_name);}

   155   }

   156   #undef __REMOVE__

   157 }

   158     

   159 

   160 /* returns true if compatible function/FB invocation, otherwise returns false */

   161 /* Assumes that the candidate_datatype lists of all the parameters being passed haved already been filled in */

   162 /*

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

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

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

   166  */

   167 bool fill_candidate_datatypes_c::match_nonformal_call(symbol_c *f_call, symbol_c *f_decl) {

   168 	symbol_c *call_param_value,  *param_datatype;

   169 	identifier_c *param_name;

   170 	function_param_iterator_c       fp_iterator(f_decl);

   171 	function_call_param_iterator_c fcp_iterator(f_call);

   172 	int extensible_parameter_highest_index = -1;

   173 	unsigned int i;

   174 

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

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

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

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

   179 		 */

   180 		do {

   181 			param_name = fp_iterator.next();

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

   183 			if(param_name == NULL) return false;

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

   185 

   186 		/* TODO: verify if it is lvalue when INOUT or OUTPUT parameters! */

   187 		/* Get the parameter type */

   188 		param_datatype = base_type(fp_iterator.param_type());

   189 		

   190 		/* check whether one of the candidate_data_types of the value being passed is the same as the param_type */

   191 		if (search_in_candidate_datatype_list(param_datatype, call_param_value->candidate_datatypes) < 0)

   192 			return false; /* return false if param_type not in the list! */

   193 	}

   194 	/* call is compatible! */

   195 	return true;

   196 }

   197 

   198 

   199 

   200 /* returns true if compatible function/FB invocation, otherwise returns false */

   201 /* Assumes that the candidate_datatype lists of all the parameters being passed haved already been filled in */

   202 bool fill_candidate_datatypes_c::match_formal_call(symbol_c *f_call, symbol_c *f_decl, symbol_c **first_param_datatype) {

   203 	symbol_c *call_param_value, *call_param_name, *param_datatype;

   204 	symbol_c *verify_duplicate_param;

   205 	identifier_c *param_name;

   206 	function_param_iterator_c       fp_iterator(f_decl);

   207 	function_call_param_iterator_c fcp_iterator(f_call);

   208 	int extensible_parameter_highest_index = -1;

   209 	identifier_c *extensible_parameter_name;

   210 	unsigned int i;

   211 	bool is_first_param = true;

   212 

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

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

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

   216 		call_param_value = fcp_iterator.get_current_value();

   217 		/* the following should never occur. If it does, then we have a bug in our code... */

   218 		if (NULL == call_param_value) ERROR;

   219 

   220 		/* Obtaining the assignment direction:  := (assign_in) or => (assign_out) */

   221 		function_call_param_iterator_c::assign_direction_t call_param_dir = fcp_iterator.get_assign_direction();

   222 

   223 		/* Checking if there are duplicated parameter values */

   224 		verify_duplicate_param = fcp_iterator.search_f(call_param_name);

   225 		if(verify_duplicate_param != call_param_value)

   226 			return false;

   227 

   228 		/* Obtaining the type of the value being passed in the function call */

   229 		std::vector <symbol_c *>&call_param_types = call_param_value->candidate_datatypes;

   230 

   231 		/* Find the corresponding parameter in function declaration */

   232 		param_name = fp_iterator.search(call_param_name);

   233 		if(param_name == NULL) return false;

   234 		/* Get the parameter data type */

   235 		param_datatype = base_type(fp_iterator.param_type());

   236 		/* Get the parameter direction: IN, OUT, IN_OUT */

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

   238 

   239 		/* check whether direction (IN, OUT, IN_OUT) and assignment types (:= , =>) are compatible !!! */

   240 		if          (function_call_param_iterator_c::assign_in  == call_param_dir) {

   241 			if ((function_param_iterator_c::direction_in    != param_dir) &&

   242 			    (function_param_iterator_c::direction_inout != param_dir))

   243 				return false;

   244 		} else if   (function_call_param_iterator_c::assign_out == call_param_dir) {

   245 			if ((function_param_iterator_c::direction_out   != param_dir))

   246 				return false;

   247 		} else ERROR;

   248 		

   249 		/* check whether one of the candidate_data_types of the value being passed is the same as the param_type */

   250 		if (search_in_candidate_datatype_list(param_datatype, call_param_types) < 0)

   251 			return false; /* return false if param_type not in the list! */

   252 		

   253 		/* If this is the first parameter, then copy the datatype to *first_param_datatype */

   254 		if (is_first_param)

   255 			if (NULL != first_param_datatype)

   256 				*first_param_datatype = param_datatype;

   257 		is_first_param = false;

   258 	}

   259 	/* call is compatible! */

   260 	return true;

   261 }

   262 

   263 

   264 

   265 

   266 /* Handle a generic function call!

   267  * Assumes that the parameter_list containing the values being passed in this function invocation

   268  * has already had all the candidate_datatype lists filled in!

   269  *

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

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

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

   273  */

   274 /*

   275 typedef struct {

   276   symbol_c *function_name,

   277   symbol_c *nonformal_operand_list,

   278   symbol_c *   formal_operand_list,

   279 

   280   std::vector <symbol_c *> &candidate_functions,  

   281   symbol_c &*called_function_declaration,

   282   int      &extensible_param_count

   283 } generic_function_call_t;

   284 */

   285 /*

   286 void narrow_candidate_datatypes_c::narrow_function_invocation(symbol_c *fcall, generic_function_call_t fcall_data) {

   287 void *fill_candidate_datatypes_c::handle_function_call(symbol_c *f_call, symbol_c *function_name, invocation_type_t invocation_type,

   288                                                        std::vector <symbol_c *> *candidate_datatypes,

   289                                                        std::vector <symbol_c *> *candidate_functions) {

   290   */

   291 void fill_candidate_datatypes_c::handle_function_call(symbol_c *fcall, generic_function_call_t fcall_data) {

   292 	function_declaration_c *f_decl;

   293 	list_c *parameter_list;

   294 	list_c *parameter_candidate_datatypes;

   295 	symbol_c *returned_parameter_type;

   296 

   297 	if (debug) std::cout << "function()\n";

   298 

   299 	function_symtable_t::iterator lower = function_symtable.lower_bound(fcall_data.function_name);

   300 	function_symtable_t::iterator upper = function_symtable.upper_bound(fcall_data.function_name);

   301 	/* If the name of the function being called is not found in the function symbol table, then this is an invalid call */

   302 	/* Since the lexical parser already checks for this, then if this occurs then we have an internal compiler error. */

   303 	if (lower == function_symtable.end()) ERROR;

   304 	

   305 	/* Look for all compatible function declarations, and add their return datatypes 

   306 	 * to the candidate_datatype list of this function invocation. 

   307 	 *

   308 	 * If only one function exists, we add its return datatype to the candidate_datatype list,

   309 	 * even if the parameters passed to it are invalid.

   310 	 * This guarantees that the remainder of the expression in which the function call is inserted

   311 	 * is treated as if the function call returns correctly, and therefore does not generate

   312 	 * spurious error messages.

   313 	 * Even if the parameters to the function call are invalid, doing this is still safe, as the 

   314 	 * expressions inside the function call will themselves have erros and will  guarantee that 

   315 	 * compilation is aborted in stage3 (in print_datatypes_error_c).

   316 	 */

   317 	if (function_symtable.multiplicity(fcall_data.function_name) == 1) {

   318 		f_decl = function_symtable.get_value(lower);

   319 		returned_parameter_type = base_type(f_decl->type_name);

   320 		if (add_datatype_to_candidate_list(fcall, returned_parameter_type))

   321 			/* we only add it to the function declaration list if this entry was not already present in the candidate datatype list! */

   322 			fcall_data.candidate_functions.push_back(f_decl);

   323 		

   324 	}

   325 	for(; lower != upper; lower++) {

   326 		bool compatible = false;

   327 		

   328 		f_decl = function_symtable.get_value(lower);

   329 		/* Check if function declaration in symbol_table is compatible with parameters */

   330 		if (NULL != fcall_data.nonformal_operand_list) compatible=match_nonformal_call(fcall, f_decl);

   331 		if (NULL != fcall_data.   formal_operand_list) compatible=   match_formal_call(fcall, f_decl);

   332 		if (compatible) {

   333 			/* Add the data type returned by the called functions. 

   334 			 * However, only do this if this data type is not already present in the candidate_datatypes list_c

   335 			 */

   336 			returned_parameter_type = base_type(f_decl->type_name);		

   337 			if (add_datatype_to_candidate_list(fcall, returned_parameter_type))

   338 				/* we only add it to the function declaration list if this entry was not already present in the candidate datatype list! */

   339 				fcall_data.candidate_functions.push_back(f_decl);

   340 		}

   341 	}

   342 	if (debug) std::cout << "end_function() [" << fcall->candidate_datatypes.size() << "] result.\n";

   343 	return;

   344 }

   345 

   346 

   347 /* handle implicit FB call in IL.

   348  * e.g.  CLK ton_var

   349  *        CU counter_var

   350  */

   351 void *fill_candidate_datatypes_c::handle_implicit_il_fb_call(symbol_c *il_instruction, const char *param_name, symbol_c *&called_fb_declaration) {

   352 	symbol_c *fb_type_id = search_varfb_instance_type->get_basetype_id(il_operand);

   353   	/* Although a call to a non-declared FB is a semantic error, this is currently caught by stage 2! */

   354 	if (NULL == fb_type_id) ERROR;

   355 

   356 	function_block_declaration_c *fb_decl = function_block_type_symtable.find_value(fb_type_id);

   357 	if (function_block_type_symtable.end_value() == fb_decl)

   358 		/* The il_operand is not the name of a FB instance. Most probably it is the name of a variable of some other type.

   359 		 * this is a semantic error.

   360 		 */

   361 		fb_decl = NULL;

   362 	

   363 	/* The narrow_candidate_datatypes_c does not rely on this called_fb_declaration pointer being == NULL to conclude that

   364 	 * we have a datatype incompatibility error, so we set it to fb_decl to allow the print_datatype_error_c to print out

   365 	 * more informative error messages!

   366 	 */

   367 	called_fb_declaration = fb_decl;

   368 

   369 	/* This implicit FB call does not change the value stored in the current/default IL variable */

   370 	/* It does, however, require that the datatype be compatible with the input parameter of the FB being called. 

   371 	 * If we were to follow the filling & narrowing algorithm correctly (implemented in fill_candidate_datatypes_c

   372 	 * & narrow_candidate_datatypes_c respectively), we should be restricting the candidate_datatpes to the datatypes

   373 	 * that are compatible to the FB call. 

   374 	 * However, doing the above will often result in some very confusing error messages for the user, especially in the case

   375 	 * in which the FB call is wrong, so the resulting cadidate datatypes is an empty list. In this case, the user would see

   376 	 * many error messages related to the IL instructions that follow the FB call, even though those IL instructions may be perfectly

   377 	 * correct.

   378 	 * For now, we will simply let the narrow_candidate_datatypes_c verify if the datatypes are compatible (something that should be done

   379 	 * here).

   380 	 */

   381 	if (NULL != prev_il_instruction)

   382 		il_instruction->candidate_datatypes = prev_il_instruction->candidate_datatypes; 

   383 

   384 	if (debug) std::cout << "handle_implicit_il_fb_call() [" << prev_il_instruction->candidate_datatypes.size() << "] ==> " << il_instruction->candidate_datatypes.size() << " result.\n";

   385 	return NULL;

   386 }

   387 

   388 

   389 

   390 

   391 /* handle a binary IL operator, like ADD, SUB, etc... */

   392 void *fill_candidate_datatypes_c::handle_binary_operator(const struct widen_entry widen_table[], symbol_c *symbol, symbol_c *l_expr, symbol_c *r_expr) {

   393 	if (NULL == l_expr) /* if no prev_il_instruction */

   394 		return NULL; 

   395 

   396 	for(unsigned int i = 0; i < l_expr->candidate_datatypes.size(); i++)

   397 		for(unsigned int j = 0; j < r_expr->candidate_datatypes.size(); j++)

   398 			/* NOTE: add_datatype_to_candidate_list() will only really add the datatype if it is != NULL !!! */

   399 			add_datatype_to_candidate_list(symbol, widening_conversion(l_expr->candidate_datatypes[i], r_expr->candidate_datatypes[j], widen_table));

   400 	remove_incompatible_datatypes(symbol);

   401 	if (debug) std::cout <<  "[" << l_expr->candidate_datatypes.size() << "," << r_expr->candidate_datatypes.size() << "] ==> "  << symbol->candidate_datatypes.size() << " result.\n";

   402 	return NULL;

   403 }

   404 

   405 

   406 /* handle a binary ST expression, like '+', '-', etc... */

   407 void *fill_candidate_datatypes_c::handle_binary_expression(const struct widen_entry widen_table[], symbol_c *symbol, symbol_c *l_expr, symbol_c *r_expr) {

   408 	l_expr->accept(*this);

   409 	r_expr->accept(*this);

   410 	return handle_binary_operator(widen_table, symbol, l_expr, r_expr);

   411 }

   412 

   413 

   414 

   415 

   416 /* a helper function... */

   417 symbol_c *fill_candidate_datatypes_c::base_type(symbol_c *symbol) {

   418 	/* NOTE: symbol == NULL is valid. It will occur when, for e.g., an undefined/undeclared symbolic_variable is used

   419 	 *       in the code.

   420 	 */

   421 	if (symbol == NULL) return NULL;

   422 	return (symbol_c *)symbol->accept(search_base_type);

   423 }

   424 

   425 /*********************/

   426 /* B 1.2 - Constants */

   427 /*********************/

   428 /******************************/

   429 /* B 1.2.1 - Numeric Literals */

   430 /******************************/

   431 #define sizeoftype(symbol) get_sizeof_datatype_c::getsize(symbol)

   432 

   433 void *fill_candidate_datatypes_c::handle_any_integer(symbol_c *symbol) {

   434 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::bool_type_name,  &search_constant_type_c::safebool_type_name);

   435 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::byte_type_name,  &search_constant_type_c::safebyte_type_name);

   436 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::word_type_name,  &search_constant_type_c::safeword_type_name);

   437 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::dword_type_name, &search_constant_type_c::safedword_type_name);

   438 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::lword_type_name, &search_constant_type_c::safelword_type_name);

   439 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::sint_type_name,  &search_constant_type_c::safesint_type_name);

   440 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::int_type_name,   &search_constant_type_c::safeint_type_name);

   441 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::dint_type_name,  &search_constant_type_c::safedint_type_name);

   442 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::lint_type_name,  &search_constant_type_c::safelint_type_name);

   443 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::usint_type_name, &search_constant_type_c::safeusint_type_name);

   444 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::uint_type_name,  &search_constant_type_c::safeuint_type_name);

   445 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::udint_type_name, &search_constant_type_c::safeudint_type_name);

   446 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::ulint_type_name, &search_constant_type_c::safeulint_type_name);

   447 	remove_incompatible_datatypes(symbol);

   448 	if (debug) std::cout << "ANY_INT [" << symbol->candidate_datatypes.size()<< "]" << std::endl;

   449 	return NULL;

   450 }

   451 

   452 

   453 

   454 void *fill_candidate_datatypes_c::handle_any_real(symbol_c *symbol) {

   455 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::real_type_name,  &search_constant_type_c::safereal_type_name);

   456 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::lreal_type_name, &search_constant_type_c::safelreal_type_name);

   457 	remove_incompatible_datatypes(symbol);

   458 	if (debug) std::cout << "ANY_REAL [" << symbol->candidate_datatypes.size() << "]" << std::endl;

   459 	return NULL;

   460 }

   461 

   462 

   463 

   464 void *fill_candidate_datatypes_c::handle_any_literal(symbol_c *symbol, symbol_c *symbol_value, symbol_c *symbol_type) {

   465 	symbol_value->accept(*this);

   466 	if (search_in_candidate_datatype_list(symbol_type, symbol_value->candidate_datatypes) >= 0)

   467 		add_datatype_to_candidate_list(symbol, symbol_type);

   468 	remove_incompatible_datatypes(symbol);

   469 	if (debug) std::cout << "XXX_LITERAL [" << symbol->candidate_datatypes.size() << "]\n";

   470 	return NULL;

   471 }

   472 

   473 

   474 

   475 void *fill_candidate_datatypes_c::visit(    real_c *symbol) {return handle_any_real(symbol);}

   476 void *fill_candidate_datatypes_c::visit(neg_real_c *symbol) {return handle_any_real(symbol);}

   477 

   478 

   479 

   480 void *fill_candidate_datatypes_c::visit(neg_integer_c *symbol) {

   481 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::int_type_name, &search_constant_type_c::safeint_type_name);

   482 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::sint_type_name, &search_constant_type_c::safesint_type_name);

   483 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::dint_type_name, &search_constant_type_c::safedint_type_name);

   484 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::lint_type_name, &search_constant_type_c::safelint_type_name);

   485 	remove_incompatible_datatypes(symbol);

   486 	if (debug) std::cout << "neg ANY_INT [" << symbol->candidate_datatypes.size() << "]" << std::endl;

   487 	return NULL;

   488 }

   489 

   490 

   491 

   492 void *fill_candidate_datatypes_c::visit(integer_c        *symbol) {return handle_any_integer(symbol);}

   493 void *fill_candidate_datatypes_c::visit(binary_integer_c *symbol) {return handle_any_integer(symbol);}

   494 void *fill_candidate_datatypes_c::visit(octal_integer_c  *symbol) {return handle_any_integer(symbol);}

   495 void *fill_candidate_datatypes_c::visit(hex_integer_c    *symbol) {return handle_any_integer(symbol);}

   496 

   497 

   498 

   499 // SYM_REF2(integer_literal_c, type, value)

   500 /*

   501  * integer_literal:

   502  *   integer_type_name '#' signed_integer

   503  * | integer_type_name '#' binary_integer

   504  * | integer_type_name '#' octal_integer

   505  * | integer_type_name '#' hex_integer

   506  */

   507 void *fill_candidate_datatypes_c::visit(   integer_literal_c *symbol) {return handle_any_literal(symbol, symbol->value, symbol->type);}

   508 void *fill_candidate_datatypes_c::visit(      real_literal_c *symbol) {return handle_any_literal(symbol, symbol->value, symbol->type);}

   509 void *fill_candidate_datatypes_c::visit(bit_string_literal_c *symbol) {return handle_any_literal(symbol, symbol->value, symbol->type);}

   510 

   511 void *fill_candidate_datatypes_c::visit(   boolean_literal_c *symbol) {

   512 	if (NULL != symbol->type) return handle_any_literal(symbol, symbol->value, symbol->type);

   513 

   514 	symbol->value->accept(*this);

   515 	symbol->candidate_datatypes = symbol->value->candidate_datatypes;

   516 	return NULL;

   517 }

   518 

   519 

   520 void *fill_candidate_datatypes_c::visit(boolean_true_c *symbol) {

   521 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::bool_type_name, &search_constant_type_c::safebool_type_name);

   522 	return NULL;

   523 }

   524 

   525 void *fill_candidate_datatypes_c::visit(boolean_false_c *symbol) {

   526 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::bool_type_name, &search_constant_type_c::safebool_type_name);

   527 	return NULL;

   528 }

   529 

   530 /*******************************/

   531 /* B.1.2.2   Character Strings */

   532 /*******************************/

   533 void *fill_candidate_datatypes_c::visit(double_byte_character_string_c *symbol) {

   534 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::wstring_type_name, &search_constant_type_c::safewstring_type_name);

   535 	return NULL;

   536 }

   537 

   538 void *fill_candidate_datatypes_c::visit(single_byte_character_string_c *symbol) {

   539 	add_2datatypes_to_candidate_list(symbol, &search_constant_type_c::string_type_name, &search_constant_type_c::safestring_type_name);

   540 	return NULL;

   541 }

   542 

   543 /***************************/

   544 /* B 1.2.3 - Time Literals */

   545 /***************************/

   546 /************************/

   547 /* B 1.2.3.1 - Duration */

   548 /************************/

   549 void *fill_candidate_datatypes_c::visit(duration_c *symbol) {

   550 	/* TODO: check whether the literal follows the rules specified in section '2.2.3.1 Duration' of the standard! */

   551 	

   552 	add_datatype_to_candidate_list(symbol, symbol->type_name);

   553 	if (debug) std::cout << "TIME_LITERAL [" << symbol->candidate_datatypes.size() << "]\n";

   554 	return NULL;

   555 }

   556 

   557 /************************************/

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

   559 /************************************/

   560 void *fill_candidate_datatypes_c::visit(time_of_day_c   *symbol) {add_datatype_to_candidate_list(symbol, symbol->type_name); return NULL;}

   561 void *fill_candidate_datatypes_c::visit(date_c          *symbol) {add_datatype_to_candidate_list(symbol, symbol->type_name); return NULL;}

   562 void *fill_candidate_datatypes_c::visit(date_and_time_c *symbol) {add_datatype_to_candidate_list(symbol, symbol->type_name); return NULL;}

   563 

   564 /**********************/

   565 /* B 1.3 - Data types */

   566 /**********************/

   567 /********************************/

   568 /* B 1.3.3 - Derived data types */

   569 /********************************/

   570 

   571 /* simple_specification ASSIGN constant */

   572 // SYM_REF2(simple_spec_init_c, simple_specification, constant)

   573 void *fill_candidate_datatypes_c::visit(simple_spec_init_c *symbol) {

   574 	if (NULL != symbol->constant) symbol->constant->accept(*this);

   575 	add_datatype_to_candidate_list(symbol->simple_specification, base_type(symbol->simple_specification));

   576 	symbol->candidate_datatypes = symbol->simple_specification->candidate_datatypes;

   577 	/* NOTE: Even if the constant and the type are of incompatible data types, we let the

   578 	 *       simple_spec_init_c object inherit the data type of the type declaration (simple_specification)

   579 	 *       This will let us produce more informative error messages when checking data type compatibility

   580 	 *       with located variables (AT %QW3.4 : WORD).

   581 	 */

   582 	// if (NULL != symbol->constant) intersect_candidate_datatype_list(symbol /*origin, dest.*/, symbol->constant /*with*/);

   583 	return NULL;

   584 }

   585 

   586 /*  signed_integer DOTDOT signed_integer */

   587 // SYM_REF2(subrange_c, lower_limit, upper_limit)

   588 void *fill_candidate_datatypes_c::visit(subrange_c *symbol) {

   589 	symbol->lower_limit->accept(*this);

   590 	symbol->upper_limit->accept(*this);

   591 	

   592 	for (unsigned int u = 0; u < symbol->upper_limit->candidate_datatypes.size(); u++) {

   593 		for(unsigned int l = 0; l < symbol->lower_limit->candidate_datatypes.size(); l++) {

   594 			if (is_type_equal(symbol->upper_limit->candidate_datatypes[u], symbol->lower_limit->candidate_datatypes[l]))

   595 				add_datatype_to_candidate_list(symbol, symbol->lower_limit->candidate_datatypes[l]);

   596 		}

   597 	}

   598 	return NULL;

   599 }

   600 

   601 /*  TYPE type_declaration_list END_TYPE */

   602 // SYM_REF1(data_type_declaration_c, type_declaration_list)

   603 /* NOTE: Not required. already handled by iterator_visitor_c base class */

   604 /*

   605 void *fill_candidate_datatypes_c::visit(data_type_declaration_c *symbol) {

   606 	symbol->type_declaration_list->accept(*this);

   607 	return NULL;

   608 }

   609 */

   610 

   611 void *fill_candidate_datatypes_c::visit(enumerated_value_c *symbol) {

   612 	symbol_c *enumerated_type;

   613 

   614 	if (NULL != symbol->type)

   615 		enumerated_type = symbol->type;

   616 	else {

   617 		enumerated_type = enumerated_value_symtable.find_value(symbol->value);

   618 		if (enumerated_type == enumerated_value_symtable.end_value())

   619 			enumerated_type = NULL;

   620 	}

   621 	enumerated_type = base_type(enumerated_type);

   622 	if (NULL != enumerated_type)

   623 		add_datatype_to_candidate_list(symbol, enumerated_type);

   624 

   625 	if (debug) std::cout << "ENUMERATE [" << symbol->candidate_datatypes.size() << "]\n";

   626 	return NULL;

   627 }

   628 

   629 

   630 /*********************/

   631 /* B 1.4 - Variables */

   632 /*********************/

   633 void *fill_candidate_datatypes_c::visit(symbolic_variable_c *symbol) {

   634 	add_datatype_to_candidate_list(symbol, search_varfb_instance_type->get_basetype_decl(symbol)); /* will only add if non NULL */

   635 	if (debug) std::cout << "VAR [" << symbol->candidate_datatypes.size() << "]\n";

   636 	return NULL;

   637 }

   638 

   639 

   640 /********************************************/

   641 /* B 1.4.1 - Directly Represented Variables */

   642 /********************************************/

   643 void *fill_candidate_datatypes_c::visit(direct_variable_c *symbol) {

   644 	/* Comment added by mario:

   645 	 * The following code is safe, actually, as the lexical parser guarantees the correct IEC61131-3 syntax was used.

   646 	 */

   647 	/* However, we should probably add an assertion in case we later change the lexical parser! */

   648 	/* if (symbol->value == NULL) ERROR;

   649 	 * if (symbol->value[0] == '\0') ERROR;

   650 	 * if (symbol->value[1] == '\0') ERROR;

   651 	 */

   652 	switch (symbol->value[2]) {

   653 		case 'x': case 'X': /* bit   -  1 bit  */ add_datatype_to_candidate_list(symbol, &search_constant_type_c::bool_type_name);  break;

   654 		case 'b': case 'B': /* byte  -  8 bits */ add_datatype_to_candidate_list(symbol, &search_constant_type_c::byte_type_name);  break;

   655 		case 'w': case 'W': /* word  - 16 bits */ add_datatype_to_candidate_list(symbol, &search_constant_type_c::word_type_name);  break;

   656 		case 'd': case 'D': /* dword - 32 bits */ add_datatype_to_candidate_list(symbol, &search_constant_type_c::dword_type_name); break;

   657 		case 'l': case 'L': /* lword - 64 bits */ add_datatype_to_candidate_list(symbol, &search_constant_type_c::lword_type_name); break;

   658         	          /* if none of the above, then the empty string was used <=> boolean */

   659 		default:                        add_datatype_to_candidate_list(symbol, &search_constant_type_c::bool_type_name);  break;

   660 	}

   661 	return NULL;

   662 }

   663 

   664 /*************************************/

   665 /* B 1.4.2 - Multi-element variables */

   666 /*************************************/

   667 /*  subscripted_variable '[' subscript_list ']' */

   668 // SYM_REF2(array_variable_c, subscripted_variable, subscript_list)

   669 void *fill_candidate_datatypes_c::visit(array_variable_c *symbol) {

   670 	/* get the declaration of the data type __stored__ in the array... */

   671 	/* if we were to want the data type of the array itself, then we should call_param_name

   672 	 * search_varfb_instance_type->get_basetype_decl(symbol->subscripted_variable)

   673 	 */

   674 	symbol_c *result = search_varfb_instance_type->get_basetype_decl(symbol);

   675 	if (NULL != result) add_datatype_to_candidate_list(symbol, result);

   676 	

   677 	/* recursively call the subscript list, so we can check the data types of the expressions used for the subscripts */

   678 	symbol->subscript_list->accept(*this);

   679 

   680 	if (debug) std::cout << "ARRAY_VAR [" << symbol->candidate_datatypes.size() << "]\n";	

   681 	return NULL;

   682 }

   683 

   684 

   685 /* subscript_list ',' subscript */

   686 // SYM_LIST(subscript_list_c)

   687 /* NOTE: we inherit from iterator visitor, so we do not need to implement this method... */

   688 // void *fill_candidate_datatypes_c::visit(subscript_list_c *symbol)

   689 

   690 

   691 /*  record_variable '.' field_selector */

   692 /*  WARNING: input and/or output variables of function blocks

   693  *           may be accessed as fields of a structured variable!

   694  *           Code handling a structured_variable_c must take

   695  *           this into account!

   696  */

   697 // SYM_REF2(structured_variable_c, record_variable, field_selector)

   698 /* NOTE: We do not need to recursively determine the data types of each field_selector, as the search_varfb_instance_type

   699  * will do that for us. So we determine the candidate datatypes only for the full structured_variable.

   700  */

   701 void *fill_candidate_datatypes_c::visit(structured_variable_c *symbol) {

   702 	add_datatype_to_candidate_list(symbol, search_varfb_instance_type->get_basetype_decl(symbol));  /* will only add if non NULL */

   703 	return NULL;

   704 }

   705 

   706 

   707 

   708 /******************************************/

   709 /* B 1.4.3 - Declaration & Initialisation */

   710 /******************************************/

   711 

   712 void *fill_candidate_datatypes_c::visit(var1_list_c *symbol) {

   713 #if 0   /* We don't really need to set the datatype of each variable. We just check the declaration itself! */

   714   for(int i = 0; i < symbol->n; i++) {

   715     add_datatype_to_candidate_list(symbol->elements[i], search_varfb_instance_type->get_basetype_decl(symbol->elements[i])); /* will only add if non NULL */

   716   }

   717 #endif

   718   return NULL;

   719 }  

   720 

   721 

   722 /*  AT direct_variable */

   723 // SYM_REF1(location_c, direct_variable)

   724 void *fill_candidate_datatypes_c::visit(location_c *symbol) {

   725  /* This is a special situation. 

   726   *

   727   * The reason is that a located variable may be declared to be of any data type, as long as the size

   728   * matches the location (lines 1 3 and 4 of table 17). For example:

   729   *   var1 AT %MB42.0 : BYTE;

   730   *   var1 AT %MB42.1 : SINT;

   731   *   var1 AT %MB42.2 : USINT;

   732   *   var1 AT %MW64   : INT;

   733   *   var1 AT %MD56   : DINT;

   734   *   var1 AT %MD57   : REAL;

   735   *  are all valid!!

   736   *

   737   *  However, when used inside an expression, the direct variable (uses the same syntax as the location

   738   *  of a located variable) is limited to the following (ANY_BIT) data types:

   739   *    %MX --> BOOL

   740   *    %MB --> BYTE

   741   *    %MW --> WORD

   742   *    %MD --> DWORD

   743   *    %ML --> LWORD

   744   *

   745   *  So, in order to be able to analyse expressions with direct variables

   746   *   e.g:  var1 := 66 OR %MW34

   747   *  where the direct variable may only take the ANY_BIT data types, the fill_candidate_datatypes_c

   748   *  considers that only the ANY_BIT data types are allowed for a direct variable.

   749   *  However, it appears from the examples in the standard (lines 1 3 and 4 of table 17)

   750   *  a location may have any data type (presumably as long as the size in bits match).

   751   *  For this reason, a location_c may have more allowable data types than a direct_variable_c

   752   */

   753 

   754 	symbol->direct_variable->accept(*this);

   755 	for (unsigned int i = 0; i < symbol->direct_variable->candidate_datatypes.size(); i++) {

   756         	switch (get_sizeof_datatype_c::getsize(symbol->direct_variable->candidate_datatypes[i])) {

   757 			case  1: /* bit   -  1 bit  */

   758 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::bool_type_name);

   759 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::safebool_type_name);

   760 					break;

   761 			case  8: /* byte  -  8 bits */

   762 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::byte_type_name);

   763 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::safebyte_type_name);

   764 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::sint_type_name);

   765 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::safesint_type_name);

   766 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::usint_type_name);

   767 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::safeusint_type_name);

   768 					break;

   769 			case 16: /* word  - 16 bits */

   770 	 				add_datatype_to_candidate_list(symbol, &search_constant_type_c::word_type_name);

   771 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::safeword_type_name);

   772 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::int_type_name);

   773 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::safeint_type_name);

   774 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::uint_type_name);

   775 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::safeuint_type_name);

   776 					break;

   777 			case 32: /* dword - 32 bits */

   778 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::dword_type_name);

   779 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::safedword_type_name);

   780 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::dint_type_name);

   781 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::safedint_type_name);

   782 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::udint_type_name);

   783 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::safeudint_type_name);

   784 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::real_type_name);

   785 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::safereal_type_name);

   786 					break;

   787 			case 64: /* lword - 64 bits */

   788 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::lword_type_name);

   789 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::safelword_type_name);

   790 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::lint_type_name);

   791 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::safelint_type_name);

   792 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::ulint_type_name);

   793 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::safeulint_type_name);

   794 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::lreal_type_name);

   795 					add_datatype_to_candidate_list(symbol, &search_constant_type_c::safelreal_type_name);

   796 					break;

   797 			default: /* if none of the above, then no valid datatype allowed... */

   798 					break;

   799 		} /* switch() */

   800 	} /* for */

   801 

   802 	return NULL;

   803 }

   804 

   805 

   806 /*  [variable_name] location ':' located_var_spec_init */

   807 /* variable_name -> may be NULL ! */

   808 // SYM_REF3(located_var_decl_c, variable_name, location, located_var_spec_init)

   809 void *fill_candidate_datatypes_c::visit(located_var_decl_c *symbol) {

   810   symbol->located_var_spec_init->accept(*this);

   811   symbol->location->accept(*this);

   812   if (NULL != symbol->variable_name) {

   813     symbol->variable_name->candidate_datatypes = symbol->location->candidate_datatypes;

   814     intersect_candidate_datatype_list(symbol->variable_name /*origin, dest.*/, symbol->located_var_spec_init /*with*/);

   815   }

   816   return NULL;

   817 }  

   818 

   819 

   820 

   821 

   822 

   823 /************************************/

   824 /* B 1.5 Program organization units */

   825 /************************************/

   826 /*********************/

   827 /* B 1.5.1 Functions */

   828 /*********************/

   829 void *fill_candidate_datatypes_c::visit(function_declaration_c *symbol) {

   830 	if (debug) printf("Filling candidate data types list of function %s\n", ((token_c *)(symbol->derived_function_name))->value);

   831 	search_varfb_instance_type = new search_varfb_instance_type_c(symbol);

   832 	symbol->var_declarations_list->accept(*this);

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

   834 	delete search_varfb_instance_type;

   835 	search_varfb_instance_type = NULL;

   836 	return NULL;

   837 }

   838 

   839 /***************************/

   840 /* B 1.5.2 Function blocks */

   841 /***************************/

   842 void *fill_candidate_datatypes_c::visit(function_block_declaration_c *symbol) {

   843 	if (debug) printf("Filling candidate data types list of FB %s\n", ((token_c *)(symbol->fblock_name))->value);

   844 	search_varfb_instance_type = new search_varfb_instance_type_c(symbol);

   845 	symbol->var_declarations->accept(*this);

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

   847 	delete search_varfb_instance_type;

   848 	search_varfb_instance_type = NULL;

   849 	return NULL;

   850 }

   851 

   852 /**********************/

   853 /* B 1.5.3 - Programs */

   854 /**********************/

   855 void *fill_candidate_datatypes_c::visit(program_declaration_c *symbol) {

   856 	if (debug) printf("Filling candidate data types list in program %s\n", ((token_c *)(symbol->program_type_name))->value);

   857 	search_varfb_instance_type = new search_varfb_instance_type_c(symbol);

   858 	symbol->var_declarations->accept(*this);

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

   860 	delete search_varfb_instance_type;

   861 	search_varfb_instance_type = NULL;

   862 	return NULL;

   863 }

   864 

   865 

   866 

   867 /********************************/

   868 /* B 1.7 Configuration elements */

   869 /********************************/

   870 void *fill_candidate_datatypes_c::visit(configuration_declaration_c *symbol) {

   871 	// TODO !!!

   872 	/* for the moment we must return NULL so semantic analysis of remaining code is not interrupted! */

   873 	return NULL;

   874 }

   875 

   876 /****************************************/

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

   878 /****************************************/

   879 /***********************************/

   880 /* B 2.1 Instructions and Operands */

   881 /***********************************/

   882 

   883 /*| instruction_list il_instruction */

   884 // SYM_LIST(instruction_list_c)

   885 void *fill_candidate_datatypes_c::visit(instruction_list_c *symbol) {

   886 	/* In order to fill the data type candidates correctly

   887 	 * in IL instruction lists containing JMPs to labels that come before the JMP instruction

   888 	 * itself, we need to run the fill candidate datatypes algorithm twice on the Instruction List.

   889 	 * e.g.:  ...

   890 	 *          ld 23

   891 	 *   label1:st byte_var

   892 	 *          ld 34

   893 	 *          JMP label1     

   894 	 *

   895 	 * Note that the second time we run the algorithm, most of the candidate datatypes are already filled

   896 	 * in, so it will be able to produce tha correct candidate datatypes for the IL instruction referenced

   897 	 * by the label, as in the 2nd pass we already know the candidate datatypes of the JMP instruction!

   898 	 */

   899 	for(int j = 0; j < 2; j++) {

   900 		for(int i = 0; i < symbol->n; i++) {

   901 			symbol->elements[i]->accept(*this);

   902 		}

   903 	}

   904 	return NULL;

   905 }

   906 

   907 

   908 

   909 /* | label ':' [il_incomplete_instruction] eol_list */

   910 // SYM_REF2(il_instruction_c, label, il_instruction)

   911 // void *visit(instruction_list_c *symbol);

   912 void *fill_candidate_datatypes_c::visit(il_instruction_c *symbol) {

   913 	if (NULL == symbol->il_instruction) {

   914 		/* This empty/null il_instruction does not change the value of the current/default IL variable.

   915 		 * So it inherits the candidate_datatypes from it's previous IL instructions!

   916 		 */

   917 		intersect_prev_candidate_datatype_lists(symbol);

   918 	} else {

   919 		il_instruction_c fake_prev_il_instruction = *symbol;

   920 		intersect_prev_candidate_datatype_lists(&fake_prev_il_instruction);

   921 

   922 		if (symbol->prev_il_instruction.size() == 0)  prev_il_instruction = NULL;

   923 		else                                          prev_il_instruction = &fake_prev_il_instruction;

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

   925 		prev_il_instruction = NULL;

   926 

   927 		/* This object has (inherits) the same candidate datatypes as the il_instruction */

   928 		symbol->candidate_datatypes = symbol->il_instruction->candidate_datatypes;

   929 	}

   930 

   931 	return NULL;

   932 }

   933 

   934 

   935 

   936 void *fill_candidate_datatypes_c::visit(il_simple_operation_c *symbol) {

   937 	/* determine the data type of the operand */

   938 	if (NULL != symbol->il_operand) {

   939 		symbol->il_operand->accept(*this);

   940 	}

   941 	/* recursive call to fill the candidate data types list */

   942 	il_operand = symbol->il_operand;

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

   944 	il_operand = NULL;

   945 	/* This object has (inherits) the same candidate datatypes as the il_simple_operator */

   946 	symbol->candidate_datatypes = symbol->il_simple_operator->candidate_datatypes;

   947 	return NULL;

   948 }

   949 

   950 

   951 /* | function_name [il_operand_list] */

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

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

   954 void *fill_candidate_datatypes_c::visit(il_function_call_c *symbol) {

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

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

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

   958 	 *

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

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

   961 	 */

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

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

   964 

   965 	symbol->il_operand_list->accept(*this);

   966 

   967 	if (NULL != prev_il_instruction) {

   968 		((list_c *)symbol->il_operand_list)->insert_element(prev_il_instruction, 0);	

   969 

   970 		generic_function_call_t fcall_param = {

   971 			/* fcall_param.function_name               = */ symbol->function_name,

   972 			/* fcall_param.nonformal_operand_list      = */ symbol->il_operand_list,

   973 			/* fcall_param.formal_operand_list         = */ NULL,

   974 			/* enum {POU_FB, POU_function} POU_type    = */ generic_function_call_t::POU_function,

   975 			/* fcall_param.candidate_functions         = */ symbol->candidate_functions,

   976 			/* fcall_param.called_function_declaration = */ symbol->called_function_declaration,

   977 			/* fcall_param.extensible_param_count      = */ symbol->extensible_param_count

   978 		};

   979 		handle_function_call(symbol, fcall_param);

   980 

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

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

   983 	}

   984 

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

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

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

   988 		delete 	symbol->il_operand_list;

   989 		symbol->il_operand_list = NULL;

   990 	}

   991 	

   992 	if (debug) std::cout << "il_function_call_c [" << symbol->candidate_datatypes.size() << "] result.\n";

   993 	return NULL;

   994 }

   995 

   996 

   997 /* | il_expr_operator '(' [il_operand] eol_list [simple_instr_list] ')' */

   998 // SYM_REF3(il_expression_c, il_expr_operator, il_operand, simple_instr_list);

   999 void *fill_candidate_datatypes_c::visit(il_expression_c *symbol) {

  1000   symbol_c *prev_il_instruction_backup = prev_il_instruction;

  1001   

  1002   if (NULL != symbol->il_operand)

  1003     symbol->il_operand->accept(*this);

  1004 

  1005   if(symbol->simple_instr_list != NULL)

  1006     symbol->simple_instr_list->accept(*this);

  1007 

  1008   /* Now check the if the data type semantics of operation are correct,  */

  1009   il_operand = symbol->simple_instr_list;

  1010   prev_il_instruction = prev_il_instruction_backup;

  1011   symbol->il_expr_operator->accept(*this);

  1012   il_operand = NULL;

  1013   

  1014   /* This object has the same candidate datatypes as the il_expr_operator. */

  1015   symbol->candidate_datatypes = symbol->il_expr_operator->candidate_datatypes;

  1016   return NULL;

  1017 }

  1018 

  1019 

  1020 void *fill_candidate_datatypes_c::visit(il_jump_operation_c *symbol) {

  1021   /* recursive call to fill the candidate data types list */

  1022   il_operand = NULL;

  1023   symbol->il_jump_operator->accept(*this);

  1024   il_operand = NULL;

  1025   /* This object has the same candidate datatypes as the il_jump_operator. */

  1026   symbol->candidate_datatypes = symbol->il_jump_operator->candidate_datatypes;

  1027   return NULL;

  1028 }

  1029 

  1030 

  1031 /*   il_call_operator prev_declared_fb_name

  1032  * | il_call_operator prev_declared_fb_name '(' ')'

  1033  * | il_call_operator prev_declared_fb_name '(' eol_list ')'

  1034  * | il_call_operator prev_declared_fb_name '(' il_operand_list ')'

  1035  * | il_call_operator prev_declared_fb_name '(' eol_list il_param_list ')'

  1036  */

  1037 /* 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 */

  1038 // SYM_REF4(il_fb_call_c, il_call_operator, fb_name, il_operand_list, il_param_list, symbol_c *called_fb_declaration)

  1039 void *fill_candidate_datatypes_c::visit(il_fb_call_c *symbol) {

  1040 	/* We do not call

  1041 	 * fb_decl = search_varfb_instance_type->get_basetype_decl(symbol->fb_name);

  1042 	 * because we want to make sure it is a FB instance, and not some other data type...

  1043 	 */

  1044 	symbol_c *fb_type_id = search_varfb_instance_type->get_basetype_id(symbol->fb_name);

  1045 	/* Although a call to a non-declared FB is a semantic error, this is currently caught by stage 2! */

  1046 	if (NULL == fb_type_id) ERROR;

  1047 

  1048  	function_block_declaration_c *fb_decl = function_block_type_symtable.find_value(fb_type_id);

  1049 	if (function_block_type_symtable.end_value() == fb_decl) 

  1050 		/* The fb_name not the name of a FB instance. Most probably it is the name of a variable of some other type. */

  1051 		fb_decl = NULL;

  1052 

  1053 	/* Although a call to a non-declared FB is a semantic error, this is currently caught by stage 2! */

  1054 	if (NULL == fb_decl) ERROR;

  1055 

  1056 	if (symbol->  il_param_list != NULL) symbol->il_param_list->accept(*this);

  1057 	if (symbol->il_operand_list != NULL) symbol->il_operand_list->accept(*this);

  1058 

  1059 	/* The print_datatypes_error_c does not rely on this called_fb_declaration pointer being != NULL to conclude that

  1060 	 * we have a datat type incompatibility error, so setting it to the correct fb_decl is actually safe,

  1061 	 * as the compiler will never reach the compilation stage!

  1062 	 */

  1063 	symbol->called_fb_declaration = fb_decl;

  1064 

  1065 	/* Let the il_call_operator (CAL, CALC, or CALCN) determine the candidate datatypes of the il_fb_call_c... */

  1066 	/* NOTE: We ignore whether the call is 'compatible' or not when filling in the candidate datatypes list.

  1067 	 *       Even if it is not compatible, we fill in the candidate datatypes list correctly so that the following

  1068 	 *       IL instructions may be handled correctly and debuged.

  1069 	 *       Doing this is actually safe, as the parameter_list will still contain errors that will be found by

  1070 	 *       print_datatypes_error_c, so the code will never reach stage 4!

  1071 	 */

  1072 	symbol->il_call_operator->accept(*this);

  1073 	symbol->candidate_datatypes = symbol->il_call_operator->candidate_datatypes;

  1074 

  1075 	if (debug) std::cout << "FB [] ==> "  << symbol->candidate_datatypes.size() << " result.\n";

  1076 	return NULL;

  1077 }

  1078 

  1079 

  1080 /* | function_name '(' eol_list [il_param_list] ')' */

  1081 /* NOTE: The parameter 'called_function_declaration' is used to pass data between the stage 3 and stage 4. */

  1082 // SYM_REF2(il_formal_funct_call_c, function_name, il_param_list, symbol_c *called_function_declaration; int extensible_param_count;)

  1083 void *fill_candidate_datatypes_c::visit(il_formal_funct_call_c *symbol) {

  1084 	symbol->il_param_list->accept(*this);

  1085 

  1086 	generic_function_call_t fcall_param = {

  1087 		/* fcall_param.function_name               = */ symbol->function_name,

  1088 		/* fcall_param.nonformal_operand_list      = */ NULL,

  1089 		/* fcall_param.formal_operand_list         = */ symbol->il_param_list,

  1090 		/* enum {POU_FB, POU_function} POU_type    = */ generic_function_call_t::POU_function,

  1091 		/* fcall_param.candidate_functions         = */ symbol->candidate_functions,

  1092 		/* fcall_param.called_function_declaration = */ symbol->called_function_declaration,

  1093 		/* fcall_param.extensible_param_count      = */ symbol->extensible_param_count

  1094 	};

  1095 	handle_function_call(symbol, fcall_param);

  1096 

  1097 	if (debug) std::cout << "il_formal_funct_call_c [" << symbol->candidate_datatypes.size() << "] result.\n";

  1098 	return NULL;

  1099 }

  1100 

  1101 

  1102 //     void *visit(il_operand_list_c *symbol);

  1103 

  1104 

  1105 /* | simple_instr_list il_simple_instruction */

  1106 /* This object is referenced by il_expression_c objects */

  1107 void *fill_candidate_datatypes_c::visit(simple_instr_list_c *symbol) {

  1108   if (symbol->n <= 0)

  1109     return NULL;  /* List is empty! Nothing to do. */

  1110     

  1111   for(int i = 0; i < symbol->n; i++)

  1112     symbol->elements[i]->accept(*this);

  1113 

  1114   /* This object has (inherits) the same candidate datatypes as the last il_instruction */

  1115   symbol->candidate_datatypes = symbol->elements[symbol->n-1]->candidate_datatypes;

  1116   

  1117   if (debug) std::cout << "simple_instr_list_c [" << symbol->candidate_datatypes.size() << "] result.\n";

  1118   return NULL;

  1119 }

  1120 

  1121 

  1122 

  1123 

  1124 // SYM_REF1(il_simple_instruction_c, il_simple_instruction, symbol_c *prev_il_instruction;)

  1125 void *fill_candidate_datatypes_c::visit(il_simple_instruction_c *symbol) {

  1126   if (symbol->prev_il_instruction.size() > 1) ERROR; /* There should be no labeled insructions inside an IL expression! */

  1127   if (symbol->prev_il_instruction.size() == 0)  prev_il_instruction = NULL;

  1128   else                                          prev_il_instruction = symbol->prev_il_instruction[0];

  1129   symbol->il_simple_instruction->accept(*this);

  1130   prev_il_instruction = NULL;

  1131 

  1132   /* This object has (inherits) the same candidate datatypes as the il_simple_instruction it points to */

  1133   symbol->candidate_datatypes = symbol->il_simple_instruction->candidate_datatypes;

  1134   return NULL;

  1135 }