--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/stage4/generate_cc/search_varfb_instance_type.cc Wed Jan 31 15:32:38 2007 +0100
@@ -0,0 +1,259 @@
+/*
+ * (c) 2003 Mario de Sousa
+ *
+ * Offered to the public under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * This code is made available on the understanding that it will not be
+ * used in safety-critical situations without a full and competent review.
+ */
+
+/*
+ * An IEC 61131-3 IL and ST compiler.
+ *
+ * Based on the
+ * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)
+ *
+ */
+
+
+
+/* Determine the data type of a variable.
+ * The variable may be a simple variable, a function block instance, a
+ * struture element within a data structured type (a struct or a fb), or
+ * an array element.
+ * A mixture of array element of a structure element of a structure element
+ * of a .... is also suported!
+ *
+ * A reference to the relevant base type __definition__ is returned.
+ * This means that if we find that the variable is of type MY_INT,
+ * which was previously declared to be
+ * TYPE MY_INT: INT := 9;
+ * this class wil return INT, and __not__ MY_INT !!
+ *
+ *
+ * example:
+ * window.points[1].coordinate.x
+ * window.points[1].colour
+ * etc... ARE ALLOWED!
+ *
+ * This class must be passed the scope within which the
+ * variable was declared, and the variable name...
+ */
+class search_varfb_instance_type_c: public search_base_type_c {
+ private:
+ search_var_instance_decl_c search_var_instance_decl;
+ decompose_var_instance_name_c *decompose_var_instance_name;
+ symbol_c *current_structelement_name;
+
+ public:
+ search_varfb_instance_type_c(symbol_c *search_scope): search_var_instance_decl(search_scope) {
+ this->decompose_var_instance_name = NULL;
+ this->current_structelement_name = NULL;
+ }
+
+
+ symbol_c *get_type(symbol_c *variable_name) {
+ this->current_structelement_name = NULL;
+ this->decompose_var_instance_name = new decompose_var_instance_name_c(variable_name);
+ if (NULL == decompose_var_instance_name) ERROR;
+
+ /* find the part of the variable name that will appear in the
+ * variable declaration, for e.g., in window.point.x, this would be
+ * window!
+ */
+ symbol_c *var_name_part = decompose_var_instance_name->next_part();
+ if (NULL == var_name_part) ERROR;
+
+ /* Now we try to find the variable instance declaration, to determine its type... */
+ symbol_c *var_decl = search_var_instance_decl.get_decl(var_name_part);
+ if (NULL == var_decl) {
+ /* variable instance declaration not found! */
+ return NULL;
+ }
+
+ /* if it is a struct or function block, we must search the type
+ * of the struct or function block member.
+ * This is done by this class visiting the var_decl.
+ * This class, while visiting, will recursively call
+ * decompose_var_instance_name->get_next() when and if required...
+ */
+ symbol_c *res = (symbol_c *)var_decl->accept(*this);
+ if (NULL == res) ERROR;
+
+ /* make sure that we have decomposed all strcuture elements of the variable name */
+ symbol_c *var_name = decompose_var_instance_name->next_part();
+ if (NULL != var_name) ERROR;
+
+ return res;
+ }
+
+ private:
+ /* a helper function... */
+ void *visit_list(list_c *list) {
+ if (NULL == current_structelement_name) ERROR;
+
+ for(int i = 0; i < list->n; i++) {
+ void *res = list->elements[i]->accept(*this);
+ if (res != NULL)
+ return res;
+ }
+ /* not found! */
+ return NULL;
+ }
+
+ /* a helper function... */
+ void *base_type(symbol_c *symbol) {
+ search_base_type_c search_base_type;
+ return symbol->accept(search_base_type);
+ }
+
+
+ private:
+ /* We override the base class' visitor to identifier_c.
+ * This is so because the base class does not consider a function block
+ * to be a type, unlike this class that allows a variable instance
+ * of a function block type...
+ */
+ void *visit(identifier_c *type_name) {
+ /* look up the type declaration... */
+ symbol_c *fb_decl = function_block_type_symtable.find_value(type_name);
+ if (fb_decl != function_block_type_symtable.end_value())
+ /* Type declaration found!! */
+ return fb_decl->accept(*this);
+
+ /* No. It is not a function block, so we let
+ * the base class take care of it...
+ */
+ return search_base_type_c::visit(type_name);
+ }
+
+/********************************/
+/* B 1.3.3 - Derived data types */
+/********************************/
+/* structure_type_name ':' structure_specification */
+ void *visit(structure_type_declaration_c *symbol) {
+ return symbol->structure_specification->accept(*this);
+ /* NOTE: structure_specification will point to either a
+ * initialized_structure_c
+ * OR A
+ * structure_element_declaration_list_c
+ */
+ }
+
+/* structure_type_name ASSIGN structure_initialization */
+/* structure_initialization may be NULL ! */
+// SYM_REF2(initialized_structure_c, structure_type_name, structure_initialization)
+ void *visit(initialized_structure_c *symbol) {
+ /* make sure that we have decomposed all strcuture elements of the variable name */
+ symbol_c *var_name = decompose_var_instance_name->next_part();
+ if (NULL == var_name) {
+ /* this is it... !
+ * No need to look any further...
+ */
+ /* NOTE: we could simply do a
+ * return (void *)symbol;
+ * nevertheless, note that this search_varfb_instance_type_c
+ * class inherits from the search_base_type_c class,
+ * which means that it will usually return the base type,
+ * and not the derived type (*). If we are to be consistent,
+ * we should guarantee that we always return the base type.
+ * To do this we could use
+ * return (void *)symbol->accept(*this);
+ * since this class inherits from the search_base_type_c.
+ * However, in this case we don't want it to follow
+ * the structs as this search_varfb_instance_type_c does.
+ * We therefore have to create a new search_base_type_c
+ * instance to search through this type without going
+ * through the structs...
+ */
+ return base_type(symbol->structure_type_name);
+ }
+
+ /* now search the structure declaration */
+ current_structelement_name = var_name;
+ /* recursively find out the data type of var_name... */
+ return symbol->structure_type_name->accept(*this);
+ }
+
+/* helper symbol for structure_declaration */
+/* structure_declaration: STRUCT structure_element_declaration_list END_STRUCT */
+/* structure_element_declaration_list structure_element_declaration ';' */
+ void *visit(structure_element_declaration_list_c *symbol) {return visit_list(symbol);}
+
+/* structure_element_name ':' spec_init */
+ void *visit(structure_element_declaration_c *symbol) {
+ if (NULL == current_structelement_name) ERROR;
+
+ if (compare_identifiers(symbol->structure_element_name, current_structelement_name) == 0)
+ return symbol->spec_init->accept(*this);
+
+ return NULL;
+ }
+
+/* helper symbol for structure_initialization */
+/* structure_initialization: '(' structure_element_initialization_list ')' */
+/* structure_element_initialization_list ',' structure_element_initialization */
+ void *visit(structure_element_initialization_list_c *symbol) {ERROR; return NULL;} /* should never get called... */
+/* structure_element_name ASSIGN value */
+ void *visit(structure_element_initialization_c *symbol) {ERROR; return NULL;} /* should never get called... */
+
+
+
+/**************************************/
+/* B.1.5 - Program organization units */
+/**************************************/
+/*****************************/
+/* B 1.5.2 - Function Blocks */
+/*****************************/
+/* FUNCTION_BLOCK derived_function_block_name io_OR_other_var_declarations function_block_body END_FUNCTION_BLOCK */
+// SYM_REF4(function_block_declaration_c, fblock_name, var_declarations, fblock_body, unused)
+ void *visit(function_block_declaration_c *symbol) {
+ /* make sure that we have decomposed all strcuture elements of the variable name */
+
+ symbol_c *var_name = decompose_var_instance_name->next_part();
+ if (NULL == var_name) {
+ /* this is it... !
+ * No need to look any further...
+ * Note also that, unlike for the struct types, a function block may
+ * not be defined based on another (i.e. no inheritance is allowed),
+ * so this function block is already the most base type.
+ * We simply return it.
+ */
+ return (void *)symbol;
+ }
+
+ /* now search the function block declaration for the variable... */
+ search_var_instance_decl_c search_decl(symbol);
+ symbol_c *var_decl = search_decl.get_decl(var_name);
+ if (NULL == var_decl) {
+ /* variable instance declaration not found! */
+ return NULL;
+ }
+
+ /* We have found the declaration.
+ * Should we look any further?
+ */
+ var_name = decompose_var_instance_name->next_part();
+ if (NULL == var_name) {
+ /* this is it... ! */
+ return base_type(var_decl);
+ }
+
+ current_structelement_name = var_name;
+ /* recursively find out the data type of var_name... */
+ return symbol->var_declarations->accept(*this);
+ }
+
+};
+
+
+
+
+