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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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    25

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/*

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 * Conversion of il statements (i.e. IL 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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/***********************************************************************/

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/***********************************************************************/

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/***********************************************************************/

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/***********************************************************************/

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/* Returns the data type of an il_operand.

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 *

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 * Note that the il_operand may be a variable, in which case

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 * we return the type of the variable instance.

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 * The il_operand may also be a constant, in which case

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 * we return the data type of that constant.

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 *

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 * The variable instance may be a member of a structured variable,

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 * or an element in an array, or any combination of the two.

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 *

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 * The class constructor must be given the search scope

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 * (function, function block or program within which

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 * the possible il_operand variable instance was declared).

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 */

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class search_il_operand_type_c {

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  private:

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    search_varfb_instance_type_c search_varfb_instance_type;

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    search_constant_type_c search_constant_type;

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  public:

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    search_il_operand_type_c(symbol_c *search_scope): search_varfb_instance_type(search_scope) {}

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  public:

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    symbol_c *get_type(symbol_c *il_operand) {

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      symbol_c *res;

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      /* We first assume that it is a constant... */

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      res = search_constant_type.get_type(il_operand);

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      if (res != NULL) return res;

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      /* Nope, now we assume it is a variable, and determine its type... */

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      res = search_varfb_instance_type.get_type(il_operand);

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      if (NULL != res) return res;

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      /* not found */

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      return NULL;

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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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/* A new class to ouput the il default variable to c++ code

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 * We use this class, inheriting from symbol_c, so it may be used

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 * as any other symbol_c object in the intermediate parse tree,

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 * more specifically, so it can be used as any other il operand.

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 * This makes the rest of the code much easier...

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 *

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 * Nevertheless, the basic visitor class visitor_c does not know

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 * how to visit this new il_default_variable_c class, so we have

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 * to extend that too.

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 * In reality extending the basic symbols doesn't quite work out

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 * as cleanly as desired (we need to use dynamic_cast in the

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 * accept method of the il_default_variable_c), but it is cleaner

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 * than the alternative...

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 */

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class il_default_variable_c;

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/* This visitor class is not really required, we could place the

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 * visit() method directly in genertae_cc_il_c, but doing it in

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 * a seperate class makes the architecture more evident...

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 */

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class il_default_variable_visitor_c {

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  public:

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    virtual void *visit(il_default_variable_c *symbol) = 0;

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    virtual ~il_default_variable_visitor_c(void) {return;}

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};

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/* A class to print out to the resulting C++ code

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 * the IL default variable name.

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 *

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 * It includes a reference to its name,

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 * and the data type of the data currently stored

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 * in this C++ variable... This is required because the

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 * C++ variable is a union, and we must know which member

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 * of the union top reference!!

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 *

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 * Note that we also need to keep track of the data type of

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 * the value currently being stored in the default variable.

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 * This is required so we can process parenthesis,

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 *

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 * e.g. :

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 *         LD var1

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 *         AND (

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 *         LD var2

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 *         OR var3

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 *         )

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 *

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 * Note that we only execute the 'AND (' operation when we come across

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 * the ')', i.e. once we have evaluated the result of the

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 * instructions inside the parenthesis.

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 * When we do execute the 'AND (' operation, we need to know the data type

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 * of the operand, which in this case is the result of the evaluation of the

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 * instruction list inside the parenthesis. We can only know this if we

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 * keep track of the data type currently stored in the default variable!

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 *

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 * We use the current_type inside the generate_cc_il::default_variable_name variable

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 * to track this!

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 */

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class il_default_variable_c: public symbol_c {

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  public:

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    symbol_c *var_name;  /* in principle, this should point to an indentifier_c */

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    symbol_c *current_type;

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  public:

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    il_default_variable_c(const char *var_name_str, symbol_c *current_type);

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    virtual void *accept(visitor_c &visitor);

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};

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/***********************************************************************/

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/***********************************************************************/

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/***********************************************************************/

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/***********************************************************************/

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class generate_cc_il_c: public generate_cc_typedecl_c, il_default_variable_visitor_c {

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  private:

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    /* When compiling il code, it becomes necessary to determine the

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     * data type of il operands. To do this, we must first find the

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     * il operand's declaration, within the scope of the function block

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     * or function currently being processed.

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     * The following object does just that...

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     * This object instance will then later be called while the

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     * remaining il code is being handled.

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     */

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    //search_il_operand_type_c *search_il_operand_type;

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    search_expression_type_c *search_expression_type;

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    /* The initial value that should be given to the IL default variable

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     * imediately after a parenthesis is opened.

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     * This variable is only used to pass data from the

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     * il_expression_c visitor to the simple_instr_list_c visitor.

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     *

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     * e.g.:

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     *         LD var1

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     *         AND ( var2

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     *         OR var3

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     *         )

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     *

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     * In the above code sample, the line 'AND ( var2' constitutes

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     * an il_expression_c, where var2 should be loaded into the

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     * il default variable before continuing with the expression

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     * inside the parenthesis.

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     * Unfortunately, only the simple_instr_list_c may do the

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     * initial laoding of the var2 bariable following the parenthesis,

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     * so the il_expression_c visitor will have to pass 'var2' as a

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     * parameter to the simple_instr_list_c visitor.

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     * Ergo, the existance of the following parameter...!

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     */

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    symbol_c *il_default_variable_init_value;

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    /* Operand to the IL operation currently being processed... */

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    /* These variables are used to pass data from the

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     * il_simple_operation_c and il_expression_c visitors

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     * to the il operator visitors (i.e. LD_operator_c,

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     * LDN_operator_c, ST_operator_c, STN_operator_c, ...)

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     */

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    symbol_c *current_operand;

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    symbol_c *current_operand_type;

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    /* Label to which the current IL jump operation should jump to... */

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    /* This variable is used to pass data from the

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     * il_jump_operation_c visitor

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     * to the il jump operator visitors (i.e. JMP_operator_c,

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     * JMPC_operator_c, JMPCN_operator_c, ...)

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     */

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    symbol_c *jump_label;

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    /* The result of the comparison IL operations (GT, EQ, LT, ...)

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     * is a boolean variable.

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     * This class keeps track of the current data type stored in the

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     * il default variable. This is usually done by keeping a reference

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     * to the data type of the last operand. Nevertheless, in the case of

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     * the comparison IL operators, the data type of the result (a boolean)

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     * is not the data type of the operand. We therefore need an object

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     * of the boolean data type to keep as a reference of the current

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     * data type.

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     * The following object is it...

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     */

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    bool_type_name_c bool_type;

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    /* the data type of the IL default variable... */

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    #define IL_DEFVAR_T VAR_LEADER "IL_DEFVAR_T"

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    /* The name of the IL default variable... */

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    #define IL_DEFVAR   VAR_LEADER "IL_DEFVAR"

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    /* The name of the variable used to pass the result of a

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     * parenthesised instruction list to the immediately preceding

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     * scope ...

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     */

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    #define IL_DEFVAR_BACK   VAR_LEADER "IL_DEFVAR_BACK"

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    il_default_variable_c default_variable_name;

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    il_default_variable_c default_variable_back_name;

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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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    temp_var_name_c temp_var_name_factory;

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    /* When calling a function block, we must first find it's type,

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     * by searching through the declarations of the variables currently

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     * in scope.

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     * This class does just that...

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     * A new class is instantiated whenever we begin generating the code

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     * for a function block type declaration, or a program declaration.

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     * This object instance will then later be called while the

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     * function block's or the program's body is being handled.

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     *

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     * Note that functions cannot contain calls to function blocks,

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     * so we do not create an object instance when handling

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     * a function declaration.

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     */

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    search_fb_instance_decl_c *search_fb_instance_decl;

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  public:

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    generate_cc_il_c(stage4out_c *s4o_ptr, symbol_c *scope, const char *variable_prefix = NULL)

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    : generate_cc_typedecl_c(s4o_ptr),

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      default_variable_name(IL_DEFVAR, NULL),

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      default_variable_back_name(IL_DEFVAR_BACK, NULL)

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    {

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      //search_il_operand_type  = new search_il_operand_type_c(scope);

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      search_expression_type = new search_expression_type_c(scope);

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      search_fb_instance_decl = new search_fb_instance_decl_c(scope);

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      current_operand = NULL;

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      current_operand_type = NULL;

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      il_default_variable_init_value = NULL;

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      this->set_variable_prefix(variable_prefix);

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    }

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    virtual ~generate_cc_il_c(void) {

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      delete search_fb_instance_decl;

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      //delete search_il_operand_type;

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      delete search_expression_type;

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    }

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    void generate(instruction_list_c *il) {

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      generate_cc_tempvardecl_c generate_cc_tempvardecl(&s4o);

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      generate_cc_tempvardecl.generate(il, &temp_var_name_factory);

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      il->accept(*this);

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    }

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    /* Declare the backup to the default variable, that will store the result

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     * of the IL operations executed inside a parenthesis...

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     */

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    void declare_backup_variable(void) {

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      s4o.print(s4o.indent_spaces);

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      s4o.print(IL_DEFVAR_T);

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      s4o.print(" ");

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      print_backup_variable();

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      s4o.print(";\n");

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    }

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    void print_backup_variable(void) {

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      this->default_variable_back_name.accept(*this);

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    }

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  private:

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    /* A helper function... */

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    /*

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    bool is_bool_type(symbol_c *type_symbol) {

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      return (NULL != dynamic_cast<bool_type_name_c *>(type_symbol));

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    }

   343

    */

   344

   345

    /* A helper function... */

   346

    void *XXX_operator(symbol_c *lo, const char *op, symbol_c *ro) {

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      if ((NULL == lo) || (NULL == ro)) ERROR;

   348

      if (NULL == op) ERROR;

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      lo->accept(*this);

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      s4o.print(op);

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      ro->accept(*this);

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      return NULL;

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    }

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    /* A helper function... */

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    void *XXX_function(const char *func, symbol_c *lo, symbol_c *ro) {

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      if ((NULL == lo) || (NULL == ro)) ERROR;

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      if (NULL == func) ERROR;

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      lo->accept(*this);

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      s4o.print(" = ");

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      s4o.print(func);

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      s4o.print("(");

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      lo->accept(*this);

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      s4o.print(", ");

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      ro->accept(*this);

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      s4o.print(")");

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      return NULL;

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    }

   371

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    /* A helper function... */

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    void *XXX_CAL_operator(const char *param_name, symbol_c *fb_name) {

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      if (NULL == fb_name) ERROR;

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      symbolic_variable_c *sv = dynamic_cast<symbolic_variable_c *>(fb_name);

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      if (NULL == sv) ERROR;

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      identifier_c *id = dynamic_cast<identifier_c *>(sv->var_name);

   378

      if (NULL == id) ERROR;

   379

   380

      identifier_c param(param_name);

   381

   382

      //SYM_REF4(il_param_assignment_c, il_assign_operator, il_operand, simple_instr_list, unused)

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      il_param_assignment_c il_param_assignment(&param, &this->default_variable_name, NULL, NULL);

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      // SYM_LIST(il_param_list_c)

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      il_param_list_c il_param_list;

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      il_param_list.add_element(&il_param_assignment);

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      CAL_operator_c CAL_operator;

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      // SYM_REF4(il_fb_call_c, il_call_operator, fb_name, il_operand_list, il_param_list)

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      il_fb_call_c il_fb_call(&CAL_operator, id, NULL, &il_param_list);

   390

   391

      il_fb_call.accept(*this);

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      return NULL;

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    }

   394

   395

    /* A helper function... */

   396

    void *CMP_operator(symbol_c *o, const char *operation) {

   397

      if (NULL == o) ERROR;

   398

      if (NULL == this->default_variable_name.current_type) ERROR;

   399

   400

      symbol_c *backup = this->default_variable_name.current_type;

   401

      this->default_variable_name.current_type = &(this->bool_type);

   402

      this->default_variable_name.accept(*this);

   403

      this->default_variable_name.current_type = backup;

   404

   405

      s4o.print(" = ");

   406

      s4o.print(operation);

   407

      this->default_variable_name.current_type->accept(*this);

   408

      s4o.print("(2, ");

   409

      this->default_variable_name.accept(*this);

   410

      s4o.print(", ");

   411

      o->accept(*this);

   412

      s4o.print(")");

   413

   414

      /* the data type resulting from this operation... */

   415

      this->default_variable_name.current_type = &(this->bool_type);

   416

      return NULL;

   417

    }

   418

   419

   420

    /* A helper function... */

   421

    void C_modifier(void) {

   422

      if (search_expression_type->is_bool_type(default_variable_name.current_type)) {

   423

        s4o.print("if (");

   424

        this->default_variable_name.accept(*this);

   425

        s4o.print(") ");

   426

      }

   427

      else {ERROR;}

   428

    }

   429

   430

    /* A helper function... */

   431

    void CN_modifier(void) {

   432

      if (search_expression_type->is_bool_type(default_variable_name.current_type)) {

   433

        s4o.print("if (!");

   434

        this->default_variable_name.accept(*this);

   435

        s4o.print(") ");

   436

      }

   437

      else {ERROR;}

   438

    }

   439

   440

   441

public:

   442

void *visit(il_default_variable_c *symbol) {

   443

  //s4o.print("il_default_variable_c VISITOR!!\n");

   444

  symbol->var_name->accept(*this);

   445

  if (NULL != symbol->current_type) {

   446

    s4o.print(".");

   447

    symbol->current_type->accept(*this);

   448

    s4o.print("var");

   449

  }

   450

  return NULL;

   451

}

   452

   453

   454

private:

   471

/****************************************/

   472

/* B.2 - Language IL (Instruction List) */

   473

/****************************************/

   474

   475

/***********************************/

   476

/* B 2.1 Instructions and Operands */

   477

/***********************************/

   478

   479

/* please see the comment before the RET_operator_c visitor for details... */

   480

#define END_LABEL VAR_LEADER "end"

   481

   482

/*| instruction_list il_instruction */

   483

void *visit(instruction_list_c *symbol) {

   484

   485

  /* Declare the backup to the default variable, that will store the result

   486

   * of the IL operations executed inside a parenthesis...

   487

   */

   488

  declare_backup_variable();

   489

   490

  /* Declare the default variable, that will store the result of the IL operations... */

   491

  s4o.print(s4o.indent_spaces);

   492

  s4o.print(IL_DEFVAR_T);

   493

  s4o.print(" ");

   494

  this->default_variable_name.accept(*this);

   495

  s4o.print(";\n\n");

   496

   497

  print_list(symbol, s4o.indent_spaces, ";\n" + s4o.indent_spaces, ";\n");

   498

   499

  /* write the label marking the end of the code block */

   500

  /* please see the comment before the RET_operator_c visitor for details... */

   501

  s4o.print("\n");

   502

  s4o.print(s4o.indent_spaces);

   503

  s4o.print(END_LABEL);

   504

  s4o.print(":\n");

   505

  s4o.indent_right();

   506

  /* since every label must be followed by at least one statement, and

   507

   * only the functions will introduce the return statement after this label,

   508

   * function blocks written in IL would result in invalid C++ code.

   509

   * To work around this we introduce the equivalent of a 'nop' operation

   510

   * to humour the compiler...

   511

   */

   512

  s4o.print(s4o.indent_spaces);

   513

  s4o.print("/* to humour the compiler, we insert a nop */\n");

   514

  s4o.print(s4o.indent_spaces);

   515

  this->default_variable_name.accept(*this);

   516

  s4o.print(" = ");

   517

  this->default_variable_name.accept(*this);

   518

  s4o.print(";\n");

   519

  s4o.indent_left();

   520

   521

  return NULL;

   522

}