etisserant@0: /*
etisserant@0:  * (c) 2003 Mario de Sousa
etisserant@0:  *
etisserant@0:  * Offered to the public under the terms of the GNU General Public License
etisserant@0:  * as published by the Free Software Foundation; either version 2 of the
etisserant@0:  * License, or (at your option) any later version.
etisserant@0:  *
etisserant@0:  * This program is distributed in the hope that it will be useful, but
etisserant@0:  * WITHOUT ANY WARRANTY; without even the implied warranty of
etisserant@0:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
etisserant@0:  * Public License for more details.
etisserant@0:  *
etisserant@0:  * This code is made available on the understanding that it will not be
etisserant@0:  * used in safety-critical situations without a full and competent review.
etisserant@0:  */
etisserant@0: 
etisserant@0: /*
etisserant@0:  * An IEC 61131-3 IL and ST compiler.
etisserant@0:  *
etisserant@0:  * Based on the
etisserant@0:  * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)
etisserant@0:  *
etisserant@0:  */
etisserant@0: 
etisserant@0: 
etisserant@0: /*
etisserant@0:  * Declare temporary variables to be later used as output parameters
etisserant@0:  * in function calls for which not all output parameters were
etisserant@0:  * defined in the original (st or il) source code.
etisserant@0:  *
etisserant@0:  * This is part of the 4th stage that generates
etisserant@0:  * a c++ source program equivalent to the IL and ST
etisserant@0:  * code.
etisserant@0:  */
etisserant@0: 
etisserant@0: 
etisserant@0: 
etisserant@0: 
etisserant@0: class temp_var_name_c {
etisserant@0:   private:
etisserant@0:     int counter;
etisserant@0: 
etisserant@0:   public:
etisserant@0:     void reset(void) {counter = 0;}
etisserant@0:     temp_var_name_c(void) {reset();}
etisserant@0: 
etisserant@0:   public:
etisserant@0:     std::string *new_name(void) {
etisserant@0:       std::string *new_str = new std::string(TEMP_VAR);
etisserant@0:       /* yikes!!! How to convert an int to a string elegantly???
etisserant@0:        * Right now I (Mario) can only think of snprintf()
etisserant@0:        * C++ must have a more elegant method!
etisserant@0:        */
etisserant@0:       int int_str_size = snprintf(NULL, 0, "%d", counter);
etisserant@0:       if (int_str_size <= 0) ERROR;
etisserant@0:       char *int_str = (char *)malloc(int_str_size+1);
etisserant@0:       if (snprintf(int_str, int_str_size+1, "%d", counter++) >= int_str_size+1) ERROR;
etisserant@0:       *new_str += int_str;
etisserant@0:       free(int_str);
etisserant@0:       return new_str;
etisserant@0:     }
etisserant@0: 
etisserant@0: };
etisserant@0: 
etisserant@0: 
etisserant@0: 
etisserant@0: /***********************************************************************/
etisserant@0: /***********************************************************************/
etisserant@0: /***********************************************************************/
etisserant@0: /***********************************************************************/
etisserant@0: 
etisserant@0: 
etisserant@0: 
etisserant@0: /* Some function calls in the body of functions or function blocks
etisserant@0:  * may leave some parameters to their default values, and
etisserant@0:  * ignore some output parameters of the function being called.
etisserant@0:  * Our conversion of ST functions to C++ does not contemplate that,
etisserant@0:  * i.e. each called function must get all it's input and output
etisserant@0:  * parameters set correctly.
etisserant@0:  * For input parameters we merely need to call the function with
etisserant@0:  * the apropriate default value, but for output parameters
etisserant@0:  * we must create temporary variables to hold the output value.
etisserant@0:  *
etisserant@0:  * We declare all the temporary output variables at the begining of
etisserant@0:  * the body of each function or function block, and use them as
etisserant@0:  * in function calls later on as they become necessary...
etisserant@0:  * Note that we cannot create these variables just before a function
etisserant@0:  * call, as the function call itself may be integrated within an
etisserant@0:  * expression, or another function call!
etisserant@0:  *
etisserant@0:  * The variables are declared in the exact same order in which they
etisserant@0:  * will be used later on during the function calls, which allows us
etisserant@0:  * to simply re-create the name that was used for the temporary variable
etisserant@0:  * instead of keeping it in some list.
etisserant@0:  * The names are recreated by the temp_var_name_factory, after reset()
etisserant@0:  * has been called!
etisserant@0:  *
etisserant@0:  * This function will genertae code similar to...
etisserant@0:  *
etisserant@0:  *     INT __TMP_0 = 23;
etisserant@0:  *     REAL __TMP_1 = 45.5;
etisserant@0:  *     ...
etisserant@0:  */
etisserant@0: 
etisserant@0: class generate_cc_tempvardecl_c: generate_cc_typedecl_c {
etisserant@0:   public:
etisserant@0:     generate_cc_tempvardecl_c(stage4out_c *s4o_ptr): generate_cc_typedecl_c(s4o_ptr) {}
etisserant@0: 
etisserant@0:     void generate(symbol_c *body, temp_var_name_c *temp_var_name_factory) {
etisserant@0:       temp_var_name_factory->reset();
etisserant@0:       function_call_iterator_c fcall_iterator(body);
etisserant@0:       for(symbol_c *finvocation = NULL; (finvocation = fcall_iterator.next()) != NULL;) {
etisserant@0:         /* get the name of the next function that gets called */
etisserant@0:         identifier_c *fcalled_name = fcall_iterator.fname();
etisserant@0:         /* get that function's declaration... */
etisserant@0:         function_declaration_c *fdecl = function_symtable.find_value(fcalled_name);
etisserant@0:         if (fdecl == function_symtable.end_value()) ERROR;
etisserant@0:         /* create iterator to iterate through each of the called function's parameters... */
etisserant@0:         function_param_iterator_c fp_iterator(fdecl);
etisserant@0: 
etisserant@0:         /* iterate through each of the called function's parameters... */
etisserant@0:         identifier_c *param_name = NULL;
etisserant@0:         function_call_param_iterator_c function_call_param_iterator(finvocation);
etisserant@0:         for(int i = 1; (param_name = fp_iterator.next()) != NULL; i++) {
etisserant@0: 
etisserant@0:           function_param_iterator_c::param_direction_t param_direction = fp_iterator.param_direction();
etisserant@0:           if (param_direction == function_param_iterator_c::direction_in)
etisserant@0:             /* ignore input only parameters...
etisserant@0:              * we do not need to create temporary variables for these!
etisserant@0:              */
etisserant@0:             continue;
etisserant@0: 
etisserant@0:           /* Get the value from a foo(<param_name> = <param_value>) style call */
etisserant@0:           symbol_c *param_value = function_call_param_iterator.search(param_name);
etisserant@0: 
etisserant@0:           /* Get the value from a foo(<param_value>) style call */
etisserant@0:           if (param_value == NULL)
etisserant@0:             param_value = function_call_param_iterator.next();
etisserant@0: 
etisserant@0:           if (param_value != NULL)
etisserant@0:             /* ignore output parameters to which a variable is passed...
etisserant@0:              * we do not need to create temporary variables for these!
etisserant@0:              */
etisserant@0:             continue;
etisserant@0: 
etisserant@0:           symbol_c *param_type = fp_iterator.param_type();
etisserant@0: 
etisserant@0:           /* get the parameter's default value */
etisserant@0:           param_value = fp_iterator.default_value();
etisserant@0: 
etisserant@0:           /* If no default value specified in function declaration,
etisserant@0:            * get the default value of this variable's type
etisserant@0:            */
etisserant@0:           if (param_value == NULL)
etisserant@0:             param_value = (symbol_c *)param_type->accept(*type_initial_value_c::instance());
etisserant@0:           if (param_value == NULL) ERROR;
etisserant@0: 
etisserant@0:           /* now declare a temporary variable, with the correct default value... */
etisserant@0:           s4o.print(s4o.indent_spaces);
etisserant@0:           param_type->accept(*this);
etisserant@0:           s4o.print(" ");
etisserant@0: 
etisserant@0:           std::string *temp_var_name = temp_var_name_factory->new_name();
etisserant@0:           s4o.print(*temp_var_name);
etisserant@0:           delete temp_var_name;
etisserant@0: 
etisserant@0:           s4o.print(" = ");
etisserant@0:           param_value->accept(*this);
etisserant@0:           s4o.print(";\n");
etisserant@0:         }
etisserant@0:       }
etisserant@0:       temp_var_name_factory->reset();
etisserant@0:       s4o.print("\n");
etisserant@0:     }
etisserant@0: };