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/*

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 *  matiec - a compiler for the programming languages defined in IEC 61131-3

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 *

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 *  Copyright (C) 2009-2012  Mario de Sousa (msousa@fe.up.pt)

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 *  Copyright (C) 2012       Manuele Conti (conti.ma@alice.it)

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 *

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 *  This program is free software: you can redistribute it and/or modify

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 *  it under the terms of the GNU General Public License as published by

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 *  the Free Software Foundation, either version 3 of the License, or

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 *  (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,

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 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

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 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

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 *  GNU General Public License for more details.

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 *

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 *  You should have received a copy of the GNU General Public License

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 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.

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 *

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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 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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/* Determine the value of an constant expression.

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 * A reference to the relevant type definition is returned.

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 *

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 * For example:

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 *       2 + 3       -> returns reference 

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 *       22.2 - 5    -> returns reference

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 *       etc...

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 */

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#include <vector>

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#include "../absyntax_utils/absyntax_utils.hh"

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#include "../util/symtable.hh"

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/* For the moment we disable constant propagation algorithm as it is not yet complete, 

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 * and due to this is currently brocken and producing incorrect results!

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 */

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#define DO_CONSTANT_PROPAGATION__ 0

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class constant_folding_c : public iterator_visitor_c {

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    search_varfb_instance_type_c *search_varfb_instance_type;

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    int error_count;

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    bool warning_found;

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    int current_display_error_level;

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    /* Pointer to the previous IL instruction, which contains the current cvalue of the data stored in the IL stack, i.e. the default variable, a.k.a. accumulator */

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    symbol_c *prev_il_instruction;

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    /* the current IL operand being analyzed */

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    symbol_c *il_operand;

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  public:

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    constant_folding_c(symbol_c *symbol = NULL);

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    virtual ~constant_folding_c(void);

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    int get_error_count();

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    int handle_var_extern_global_pair(symbol_c *extern_var_name, symbol_c *extern_var_decl, symbol_c *global_var_name, symbol_c *global_var_decl);

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    typedef symtable_c<const_value_c> map_values_t;

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  private:

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    map_values_t values;

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    void *handle_var_list_decl(symbol_c *var_list, symbol_c *type_decl);

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    void *handle_var_decl     (symbol_c *var_list, bool fixed_init_value);

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    // Flag to indicate whether the variables in the variable declaration list will always have a fixed value when the POU is executed!

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    // VAR CONSTANT ... END_VAR will always be true

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    // VAR          ... END_VAR will always be true for functions (who initialise local variables every time they are called), but false for FBs and PROGRAMS

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    bool fixed_init_value_; 

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    bool function_pou_;

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    bool is_constant(symbol_c *option);

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    bool is_retain  (symbol_c *option);

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  public:

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	#if 0

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	// not currently needed, so comment it out!...

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	/* utility functions for other stage3 algorithms to access the contant folded values */

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	/* written as static since we do not need to iteratively visit the symbols! */

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	// returns true if both symbols have the same value in all the cvalues

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	static bool is_equal_cvalue(symbol_c *symbol_1, symbol_c *symbol_2);

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	#endif

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  private:

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

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    /* B 1.2 - Constants */

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

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

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    /* B 1.2.1 - Numeric Literals */

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

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    void *visit(real_c *symbol);

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    void *visit(integer_c *symbol);

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    void *visit(neg_real_c *symbol);

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    void *visit(neg_integer_c *symbol);

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    void *visit(binary_integer_c *symbol);

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    void *visit(octal_integer_c *symbol);

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    void *visit(hex_integer_c *symbol);

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    void *visit(integer_literal_c *symbol);

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    void *visit(real_literal_c *symbol);

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    void *visit(bit_string_literal_c *symbol);

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    void *visit(boolean_literal_c *symbol);

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    void *visit(boolean_true_c *symbol);

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    void *visit(boolean_false_c *symbol);

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

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    /* B 1.2.3.1 - Duration */

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

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    void *visit(fixed_point_c *symbol);

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

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    /* B 1.4 - Variables */

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

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    void *visit(symbolic_variable_c *symbol);

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    void *visit(symbolic_constant_c *symbol);

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

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    /* B 1.4.3 - Declaration & Initialisation */

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

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    void *visit(        input_declarations_c *symbol);

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    void *visit(       output_declarations_c *symbol);

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    void *visit( input_output_declarations_c *symbol);

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    void *visit(          var_declarations_c *symbol);

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    void *visit(retentive_var_declarations_c *symbol);

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    void *visit( external_var_declarations_c *symbol);

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    void *visit(   global_var_declarations_c *symbol);

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    void *visit(  external_declaration_c     *symbol);

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    void *visit(global_var_decl_c            *symbol);

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    void *visit( var1_init_decl_c            *symbol);

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

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    /* B.1.5 - Program organization units */

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

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

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    /* B 1.5.1 - Functions */

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

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    void *visit(function_declaration_c *symbol);

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    void *visit(function_var_decls_c   *symbol);

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

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    /* B 1.5.2 - Function Blocks */

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

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    void *visit(function_block_declaration_c *symbol);

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    void *visit(            temp_var_decls_c *symbol);

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    void *visit(   non_retentive_var_decls_c *symbol);

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

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    /* B 1.5.3 - Programs */

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

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    void *visit(       program_declaration_c *symbol);

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

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    /* B 1.7 Configuration elements */

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

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    void *visit( configuration_declaration_c *symbol);

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    void *visit(      resource_declaration_c *symbol);

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

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

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

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

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    /* B 2.1 Instructions and Operands */

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

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    // void *visit(instruction_list_c *symbol); /* Not needed, since we inherit from iterator_visitor_c */

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    void *visit(il_instruction_c *symbol);

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    void *visit(il_simple_operation_c *symbol);

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    //void *visit(il_function_call_c *symbol);  /* TODO */

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    void *visit(il_expression_c *symbol);

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    void *visit(il_jump_operation_c *symbol);

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    void *visit(il_fb_call_c *symbol);

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    //void *visit(il_formal_funct_call_c *symbol);   /* TODO */

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    //void *visit(il_operand_list_c *symbol);  /* Not needed, since we inherit from iterator_visitor_c */

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    void *visit(simple_instr_list_c *symbol);

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    void *visit(il_simple_instruction_c *symbol);

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

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    /* B 2.2 Operators */

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

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    void *visit(   LD_operator_c *symbol);

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    void *visit(  LDN_operator_c *symbol);

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    void *visit(   ST_operator_c *symbol);

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    void *visit(  STN_operator_c *symbol);

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    void *visit(  NOT_operator_c *symbol);

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    void *visit(    S_operator_c *symbol);

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    void *visit(    R_operator_c *symbol);

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    void *visit(   S1_operator_c *symbol);

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    void *visit(   R1_operator_c *symbol);

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    void *visit(  CLK_operator_c *symbol);

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    void *visit(   CU_operator_c *symbol);

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    void *visit(   CD_operator_c *symbol);

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    void *visit(   PV_operator_c *symbol);

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    void *visit(   IN_operator_c *symbol);

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    void *visit(   PT_operator_c *symbol);

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    void *visit(  AND_operator_c *symbol);

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    void *visit(   OR_operator_c *symbol);

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    void *visit(  XOR_operator_c *symbol);

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    void *visit( ANDN_operator_c *symbol);

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    void *visit(  ORN_operator_c *symbol);

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    void *visit( XORN_operator_c *symbol);

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    void *visit(  ADD_operator_c *symbol);

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    void *visit(  SUB_operator_c *symbol);

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    void *visit(  MUL_operator_c *symbol);

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    void *visit(  DIV_operator_c *symbol);

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    void *visit(  MOD_operator_c *symbol);

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    void *visit(   GT_operator_c *symbol);

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    void *visit(   GE_operator_c *symbol);

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    void *visit(   EQ_operator_c *symbol);

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    void *visit(   LT_operator_c *symbol);

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    void *visit(   LE_operator_c *symbol);

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    void *visit(   NE_operator_c *symbol);

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    void *visit(  CAL_operator_c *symbol);

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    void *visit( CALC_operator_c *symbol);

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    void *visit(CALCN_operator_c *symbol);

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    void *visit(  RET_operator_c *symbol);

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    void *visit( RETC_operator_c *symbol);

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    void *visit(RETCN_operator_c *symbol);

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    void *visit(  JMP_operator_c *symbol);

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    void *visit( JMPC_operator_c *symbol);

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    void *visit(JMPCN_operator_c *symbol);

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    /* Symbol class handled together with function call checks */

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    // void *visit(il_assign_operator_c *symbol, variable_name);

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    /* Symbol class handled together with function call checks */

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    // void *visit(il_assign_operator_c *symbol, option, variable_name);

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

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    /* B.3 - Language ST (Structured Text) */

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

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

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    /* B 3.1 - Expressions */

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

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    void *visit(    or_expression_c *symbol);

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    void *visit(   xor_expression_c *symbol);

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    void *visit(   and_expression_c *symbol);

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    void *visit(   equ_expression_c *symbol);

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    void *visit(notequ_expression_c *symbol);

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    void *visit(    lt_expression_c *symbol);

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    void *visit(    gt_expression_c *symbol);

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    void *visit(    le_expression_c *symbol);

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    void *visit(    ge_expression_c *symbol);

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    void *visit(   add_expression_c *symbol);

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    void *visit(   sub_expression_c *symbol);

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    void *visit(   mul_expression_c *symbol);

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    void *visit(   div_expression_c *symbol);

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    void *visit(   mod_expression_c *symbol);

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    void *visit( power_expression_c *symbol);

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    void *visit(   neg_expression_c *symbol);

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    void *visit(   not_expression_c *symbol);

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    //void *visit(function_invocation_c *symbol); /* TODO */

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

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    /* B 3.2.1 Assignment Statements */

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

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    void *visit(assignment_statement_c *symbol);

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

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    /* B 3.2.3 Selection Statements */

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

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    void *visit(if_statement_c *symbol);

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

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    /* B 3.2.4 Iteration Statements */

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

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    void *visit(for_statement_c *symbol);

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    void *visit(while_statement_c *symbol);

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    void *visit(repeat_statement_c *symbol);

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    #endif // DO_CONSTANT_PROPAGATION__

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};

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