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