--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/stage4/generate_cc/generate_cc_tempvardecl.cc Wed Jan 31 15:32:38 2007 +0100
@@ -0,0 +1,175 @@
+/*
+ * (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)
+ *
+ */
+
+
+/*
+ * Declare temporary variables to be later used as output parameters
+ * in function calls for which not all output parameters were
+ * defined in the original (st or il) source code.
+ *
+ * This is part of the 4th stage that generates
+ * a c++ source program equivalent to the IL and ST
+ * code.
+ */
+
+
+
+
+class temp_var_name_c {
+ private:
+ int counter;
+
+ public:
+ void reset(void) {counter = 0;}
+ temp_var_name_c(void) {reset();}
+
+ public:
+ std::string *new_name(void) {
+ std::string *new_str = new std::string(TEMP_VAR);
+ /* yikes!!! How to convert an int to a string elegantly???
+ * Right now I (Mario) can only think of snprintf()
+ * C++ must have a more elegant method!
+ */
+ int int_str_size = snprintf(NULL, 0, "%d", counter);
+ if (int_str_size <= 0) ERROR;
+ char *int_str = (char *)malloc(int_str_size+1);
+ if (snprintf(int_str, int_str_size+1, "%d", counter++) >= int_str_size+1) ERROR;
+ *new_str += int_str;
+ free(int_str);
+ return new_str;
+ }
+
+};
+
+
+
+/***********************************************************************/
+/***********************************************************************/
+/***********************************************************************/
+/***********************************************************************/
+
+
+
+/* Some function calls in the body of functions or function blocks
+ * may leave some parameters to their default values, and
+ * ignore some output parameters of the function being called.
+ * Our conversion of ST functions to C++ does not contemplate that,
+ * i.e. each called function must get all it's input and output
+ * parameters set correctly.
+ * For input parameters we merely need to call the function with
+ * the apropriate default value, but for output parameters
+ * we must create temporary variables to hold the output value.
+ *
+ * We declare all the temporary output variables at the begining of
+ * the body of each function or function block, and use them as
+ * in function calls later on as they become necessary...
+ * Note that we cannot create these variables just before a function
+ * call, as the function call itself may be integrated within an
+ * expression, or another function call!
+ *
+ * The variables are declared in the exact same order in which they
+ * will be used later on during the function calls, which allows us
+ * to simply re-create the name that was used for the temporary variable
+ * instead of keeping it in some list.
+ * The names are recreated by the temp_var_name_factory, after reset()
+ * has been called!
+ *
+ * This function will genertae code similar to...
+ *
+ * INT __TMP_0 = 23;
+ * REAL __TMP_1 = 45.5;
+ * ...
+ */
+
+class generate_cc_tempvardecl_c: generate_cc_typedecl_c {
+ public:
+ generate_cc_tempvardecl_c(stage4out_c *s4o_ptr): generate_cc_typedecl_c(s4o_ptr) {}
+
+ void generate(symbol_c *body, temp_var_name_c *temp_var_name_factory) {
+ temp_var_name_factory->reset();
+ function_call_iterator_c fcall_iterator(body);
+ for(symbol_c *finvocation = NULL; (finvocation = fcall_iterator.next()) != NULL;) {
+ /* get the name of the next function that gets called */
+ identifier_c *fcalled_name = fcall_iterator.fname();
+ /* get that function's declaration... */
+ function_declaration_c *fdecl = function_symtable.find_value(fcalled_name);
+ if (fdecl == function_symtable.end_value()) ERROR;
+ /* create iterator to iterate through each of the called function's parameters... */
+ function_param_iterator_c fp_iterator(fdecl);
+
+ /* iterate through each of the called function's parameters... */
+ identifier_c *param_name = NULL;
+ function_call_param_iterator_c function_call_param_iterator(finvocation);
+ for(int i = 1; (param_name = fp_iterator.next()) != NULL; i++) {
+
+ function_param_iterator_c::param_direction_t param_direction = fp_iterator.param_direction();
+ if (param_direction == function_param_iterator_c::direction_in)
+ /* ignore input only parameters...
+ * we do not need to create temporary variables for these!
+ */
+ continue;
+
+ /* Get the value from a foo(<param_name> = <param_value>) style call */
+ symbol_c *param_value = function_call_param_iterator.search(param_name);
+
+ /* Get the value from a foo(<param_value>) style call */
+ if (param_value == NULL)
+ param_value = function_call_param_iterator.next();
+
+ if (param_value != NULL)
+ /* ignore output parameters to which a variable is passed...
+ * we do not need to create temporary variables for these!
+ */
+ continue;
+
+ symbol_c *param_type = fp_iterator.param_type();
+
+ /* get the parameter's default value */
+ param_value = fp_iterator.default_value();
+
+ /* If no default value specified in function declaration,
+ * get the default value of this variable's type
+ */
+ if (param_value == NULL)
+ param_value = (symbol_c *)param_type->accept(*type_initial_value_c::instance());
+ if (param_value == NULL) ERROR;
+
+ /* now declare a temporary variable, with the correct default value... */
+ s4o.print(s4o.indent_spaces);
+ param_type->accept(*this);
+ s4o.print(" ");
+
+ std::string *temp_var_name = temp_var_name_factory->new_name();
+ s4o.print(*temp_var_name);
+ delete temp_var_name;
+
+ s4o.print(" = ");
+ param_value->accept(*this);
+ s4o.print(";\n");
+ }
+ }
+ temp_var_name_factory->reset();
+ s4o.print("\n");
+ }
+};