1 /*

     2  * (c) 2003 Mario de Sousa

     3  *

     4  * Offered to the public under the terms of the GNU General Public License

     5  * as published by the Free Software Foundation; either version 2 of the

     6  * License, or (at your option) any later version.

     7  *

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

     9  * WITHOUT ANY WARRANTY; without even the implied warranty of

    10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General

    11  * Public License for more details.

    12  *

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

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

    15  */

    16 

    17 /*

    18  * An IEC 61131-3 IL and ST compiler.

    19  *

    20  * Based on the

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

    22  *

    23  */

    24 

    25 

    26 

    27 /* Determine the data type of a variable.

    28  * The variable may be a simple variable, a function block instance, a

    29  * struture element within a data structured type (a struct or a fb), or

    30  * an array element.

    31  * A mixture of array element of a structure element of a structure element

    32  * of a .... is also suported!

    33  *

    34  * A reference to the relevant base type __definition__ is returned.

    35  * This means that if we find that the variable is of type MY_INT,

    36  * which was previously declared to be

    37  * TYPE MY_INT: INT := 9;

    38  * this class wil return INT, and __not__ MY_INT !!

    39  *

    40  *

    41  *  example:

    42  *    window.points[1].coordinate.x

    43  *    window.points[1].colour

    44  *    etc... ARE ALLOWED!

    45  *

    46  * This class must be passed the scope within which the

    47  * variable was declared, and the variable name...

    48  */

    49 class search_varfb_instance_type_c: public search_base_type_c {

    50   private:

    51     search_var_instance_decl_c search_var_instance_decl;

    52     decompose_var_instance_name_c *decompose_var_instance_name;

    53     symbol_c *current_structelement_name;

    54     bool search_base_type;

    55 

    56   public:

    57     search_varfb_instance_type_c(symbol_c *search_scope): search_var_instance_decl(search_scope) {

    58       this->decompose_var_instance_name = NULL;

    59       this->current_structelement_name = NULL;

    60       this->search_base_type = false;

    61     }

    62 

    63     symbol_c *get_type(symbol_c *variable_name, bool base_type = true) {

    64       this->current_structelement_name = NULL;

    65       this->decompose_var_instance_name = new decompose_var_instance_name_c(variable_name);

    66       this->search_base_type = base_type;

    67       if (NULL == decompose_var_instance_name) ERROR;

    68 

    69       /* find the part of the variable name that will appear in the

    70        * variable declaration, for e.g., in window.point.x, this would be

    71        * window!

    72        */

    73       symbol_c *var_name_part = decompose_var_instance_name->next_part();

    74       if (NULL == var_name_part) ERROR;

    75       

    76       /* Now we try to find the variable instance declaration, to determine its type... */

    77       symbol_c *var_decl = search_var_instance_decl.get_decl(var_name_part);

    78       if (NULL == var_decl) {

    79         /* variable instance declaration not found! */

    80  	      ERROR;

    81       }

    82 

    83       /* if it is a struct or function block, we must search the type

    84        * of the struct or function block member.

    85        * This is done by this class visiting the var_decl.

    86        * This class, while visiting, will recursively call

    87        * decompose_var_instance_name->get_next() when and if required...

    88        */

    89       symbol_c *res = (symbol_c *)var_decl->accept(*this);

    90       if (NULL == res) ERROR;

    91 

    92       /* make sure that we have decomposed all strcuture elements of the variable name */

    93       symbol_c *var_name = decompose_var_instance_name->next_part();

    94       if (NULL != var_name) ERROR;

    95 

    96       return res;

    97     }

    98 

    99     unsigned int get_vartype(symbol_c *variable_name) {

   100       this->current_structelement_name = NULL;

   101       this->decompose_var_instance_name = new decompose_var_instance_name_c(variable_name);

   102       if (NULL == decompose_var_instance_name) ERROR;

   103 

   104       /* find the part of the variable name that will appear in the

   105        * variable declaration, for e.g., in window.point.x, this would be

   106        * window!

   107        */

   108       symbol_c *var_name_part = decompose_var_instance_name->next_part();

   109       if (NULL == var_name_part) ERROR;

   110 

   111       /* Now we try to find the variable instance declaration, to determine its type... */

   112       symbol_c *var_decl = search_var_instance_decl.get_decl(var_name_part);

   113       if (NULL == var_decl) {

   114         /* variable instance declaration not found! */

   115         return 0;

   116       }

   117 

   118       /* if it is a struct or function block, we must search the type

   119        * of the struct or function block member.

   120        * This is done by this class visiting the var_decl.

   121        * This class, while visiting, will recursively call

   122        * decompose_var_instance_name->get_next() when and if required...

   123        */

   124       unsigned int res = search_var_instance_decl.get_vartype();

   125       

   126       /* make sure that we have decomposed all strcuture elements of the variable name */

   127       symbol_c *var_name = decompose_var_instance_name->next_part();

   128       if (NULL != var_name) ERROR;

   129 

   130       return res;

   131     }

   132 

   133   private:

   134     /* a helper function... */

   135     void *visit_list(list_c *list)	{

   136       if (NULL == current_structelement_name) ERROR;

   137 

   138       for(int i = 0; i < list->n; i++) {

   139         void *res = list->elements[i]->accept(*this);

   140         if (res != NULL)

   141           return res;

   142       }

   143       /* not found! */

   144       return NULL;

   145     }

   146 

   147     /* a helper function... */

   148     void *base_type(symbol_c *symbol)	{

   149         search_base_type_c search_base_type;

   150 	return symbol->accept(search_base_type);

   151     }

   152 

   153 

   154   private:

   155     /* We override the base class' visitor to identifier_c.

   156      * This is so because the base class does not consider a function block

   157      * to be a type, unlike this class that allows a variable instance

   158      * of a function block type...

   159      */

   160     void *visit(identifier_c *type_name) {

   161       /* look up the type declaration... */

   162       symbol_c *fb_decl = function_block_type_symtable.find_value(type_name);

   163       if (fb_decl != function_block_type_symtable.end_value())

   164         /* Type declaration found!! */

   165 	return fb_decl->accept(*this);

   166 

   167       /* No. It is not a function block, so we let

   168        * the base class take care of it...

   169        */

   170       if (this->search_base_type)

   171         return search_base_type_c::visit(type_name);

   172       else

   173         return type_name;

   174     }

   175 

   176 /********************************/

   177 /* B 1.3.3 - Derived data types */

   178 /********************************/

   179 

   180 /*  identifier ':' array_spec_init */

   181     void *visit(array_type_declaration_c *symbol) {

   182       return symbol->array_spec_init->accept(*this);

   183     }

   184     

   185 /* array_specification [ASSIGN array_initialization} */

   186 /* array_initialization may be NULL ! */

   187     void *visit(array_spec_init_c *symbol) {

   188       symbol_c *var_name = decompose_var_instance_name->next_part();

   189       if (NULL != var_name)

   190         current_structelement_name = var_name;

   191       return symbol->array_specification->accept(*this);

   192     }

   193     

   194 /* ARRAY '[' array_subrange_list ']' OF non_generic_type_name */

   195     void *visit(array_specification_c *symbol) {

   196       symbol_c *var_name = decompose_var_instance_name->next_part();

   197       if (NULL != var_name)

   198         current_structelement_name = var_name;

   199       return symbol->non_generic_type_name->accept(*this);

   200     }

   201 

   202 /*  structure_type_name ':' structure_specification */

   203     void *visit(structure_type_declaration_c *symbol) {

   204       return symbol->structure_specification->accept(*this);

   205       /* NOTE: structure_specification will point to either a

   206        *       initialized_structure_c

   207        *       OR A

   208        *       structure_element_declaration_list_c

   209        */

   210     }

   211 

   212 /* structure_type_name ASSIGN structure_initialization */

   213 /* structure_initialization may be NULL ! */

   214 // SYM_REF2(initialized_structure_c, structure_type_name, structure_initialization)

   215     void *visit(initialized_structure_c *symbol)	{

   216       /* make sure that we have decomposed all strcuture elements of the variable name */

   217       symbol_c *var_name = decompose_var_instance_name->next_part();

   218       if (NULL == var_name) {

   219         /* this is it... !

   220 	  * No need to look any further...

   221 	 */

   222 	/* NOTE: we could simply do a

   223 	 *   return (void *)symbol;

   224 	 *       nevertheless, note that this search_varfb_instance_type_c

   225 	 *       class inherits from the search_base_type_c class,

   226 	 *       which means that it will usually return the base type,

   227 	 *       and not the derived type (*). If we are to be consistent,

   228 	 *       we should guarantee that we always return the base type.

   229 	 *       To do this we could use

   230 	 *   return (void *)symbol->accept(*this);

   231 	 *       since this class inherits from the search_base_type_c.

   232 	 *       However, in this case we don't want it to follow

   233 	 *       the structs as this search_varfb_instance_type_c does.

   234 	 *       We therefore have to create a new search_base_type_c

   235 	 *       instance to search through this type without going

   236 	 *       through the structs...

   237 	 */

   238         return base_type(symbol->structure_type_name);

   239       }

   240 

   241       /* now search the structure declaration */

   242       current_structelement_name = var_name;

   243       /* recursively find out the data type of var_name... */

   244       return symbol->structure_type_name->accept(*this);

   245     }

   246 

   247 /* helper symbol for structure_declaration */

   248 /* structure_declaration:  STRUCT structure_element_declaration_list END_STRUCT */

   249 /* structure_element_declaration_list structure_element_declaration ';' */

   250     void *visit(structure_element_declaration_list_c *symbol)	{

   251       return visit_list(symbol);

   252     }

   253 

   254 /*  structure_element_name ':' spec_init */

   255     void *visit(structure_element_declaration_c *symbol) {

   256       if (NULL == current_structelement_name) ERROR;

   257 

   258       if (compare_identifiers(symbol->structure_element_name, current_structelement_name) == 0)

   259         return symbol->spec_init->accept(*this);

   260 

   261       return NULL;

   262     }

   263 

   264 /* helper symbol for structure_initialization */

   265 /* structure_initialization: '(' structure_element_initialization_list ')' */

   266 /* structure_element_initialization_list ',' structure_element_initialization */

   267     void *visit(structure_element_initialization_list_c *symbol) {ERROR; return NULL;} /* should never get called... */

   268 /*  structure_element_name ASSIGN value */

   269     void *visit(structure_element_initialization_c *symbol) {ERROR; return NULL;} /* should never get called... */

   270 

   271 

   272 

   273 /**************************************/

   274 /* B.1.5 - Program organization units */

   275 /**************************************/

   276 /*****************************/

   277 /* B 1.5.2 - Function Blocks */

   278 /*****************************/

   279 /*  FUNCTION_BLOCK derived_function_block_name io_OR_other_var_declarations function_block_body END_FUNCTION_BLOCK */

   280 // SYM_REF4(function_block_declaration_c, fblock_name, var_declarations, fblock_body, unused)

   281     void *visit(function_block_declaration_c *symbol) {

   282       /* make sure that we have decomposed all strcuture elements of the variable name */

   283 

   284       symbol_c *var_name = decompose_var_instance_name->next_part();

   285       if (NULL == var_name) {

   286         /* this is it... !

   287 	 * No need to look any further...

   288 	 * Note also that, unlike for the struct types, a function block may

   289 	 * not be defined based on another (i.e. no inheritance is allowed),

   290 	 * so this function block is already the most base type.

   291 	 * We simply return it.

   292 	 */

   293 	return (void *)symbol;

   294       }

   295 

   296       /* now search the function block declaration for the variable... */

   297       search_var_instance_decl_c search_decl(symbol);

   298       symbol_c *var_decl = search_decl.get_decl(var_name);

   299       if (NULL == var_decl) {

   300         /* variable instance declaration not found! */

   301  	return NULL;

   302       }

   303 

   304       /* We have found the declaration.

   305        * Should we look any further?

   306        */

   307       var_name = decompose_var_instance_name->next_part();

   308       if (NULL == var_name) {

   309         /* this is it... ! */

   310 	return base_type(var_decl);

   311       }

   312 

   313       current_structelement_name = var_name;

   314       /* recursively find out the data type of var_name... */

   315       return symbol->var_declarations->accept(*this);

   316     }

   317 

   318 };

   319 

   320 

   321 

   322 

   323