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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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 * Determine the default initial value of a type declaration.

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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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/* Given a type definition declration, determine its default

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 * initial value. Note that types based on other types

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 * may have to iterate through each type it is based on

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 * to determine the initial value.

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 * E.g.

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 *  TYPE

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 *    A_t : INT := 10;

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 *    B_t : A_t := 20;

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 *    C_t : B_t;

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 *    D_t : C_t := 40;

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 *  END_TYPE

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 * Where the default initial value for C_t is 20!

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 */

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/* NOTE: The main program only needs one instance of

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 *       this class of object. This class

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 *       is therefore a singleton.

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 */

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class type_initial_value_c : public null_visitor_c {

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  private:

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    static type_initial_value_c *_instance;

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    /* constants for the default values of elementary data types... */

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    static real_c		*real_0;

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    static integer_c		*integer_0, *integer_1;

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    static boolean_literal_c	*bool_0;

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    static date_literal_c	*date_literal_0;

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    static daytime_c		*daytime_literal_0;

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    static duration_c		*time_0;

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    static date_c		*date_0;

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    static time_of_day_c	*tod_0;

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    static date_and_time_c	*dt_0;

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    static single_byte_character_string_c *string_0;

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    static double_byte_character_string_c *wstring_0;

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  public:

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    static type_initial_value_c *instance(void);

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  protected:

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    type_initial_value_c(void);

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  public:

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    symbol_c *get(identifier_c *type_name);

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  private:

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    void *handle_type_spec(symbol_c *base_type_name, symbol_c *type_spec_init);

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  private:

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    void *visit(identifier_c *type_name);

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

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    /* B 1.3.1 - Elementary Data Types */

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

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    void *visit(time_type_name_c *symbol);

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    void *visit(bool_type_name_c *symbol);

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    void *visit(sint_type_name_c *symbol);

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    void *visit(int_type_name_c *symbol);

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    void *visit(dint_type_name_c *symbol);

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    void *visit(lint_type_name_c *symbol);

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    void *visit(usint_type_name_c *symbol);

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    void *visit(uint_type_name_c *symbol);

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    void *visit(udint_type_name_c *symbol);

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    void *visit(ulint_type_name_c *symbol);

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    void *visit(real_type_name_c *symbol);

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    void *visit(lreal_type_name_c *symbol);

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    void *visit(date_type_name_c *symbol);

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    void *visit(tod_type_name_c *symbol);

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    void *visit(dt_type_name_c *symbol);

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    void *visit(byte_type_name_c *symbol);

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    void *visit(word_type_name_c *symbol);

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    void *visit(dword_type_name_c *symbol);

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    void *visit(lword_type_name_c *symbol);

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    void *visit(string_type_name_c *symbol);

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    void *visit(wstring_type_name_c *symbol);

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

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    /* B 1.3.3 - Derived data types */

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

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    /*  simple_type_name ':' simple_spec_init */

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    void *visit(simple_type_declaration_c *symbol);

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    /* simple_specification ASSIGN constant */

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    void *visit(simple_spec_init_c *symbol);

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    /*  subrange_type_name ':' subrange_spec_init */

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    void *visit(subrange_type_declaration_c *symbol);

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    /* subrange_specification ASSIGN signed_integer */

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    void *visit(subrange_spec_init_c *symbol);

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    /*  integer_type_name '(' subrange')' */

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    void *visit(subrange_specification_c *symbol);

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    /*  signed_integer DOTDOT signed_integer */

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    void *visit(subrange_c *symbol);

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    /*  enumerated_type_name ':' enumerated_spec_init */

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    void *visit(enumerated_type_declaration_c *symbol);

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    /* enumerated_specification ASSIGN enumerated_value */

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    void *visit(enumerated_spec_init_c *symbol);

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    /* helper symbol for enumerated_specification->enumerated_spec_init */

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    /* enumerated_value_list ',' enumerated_value */

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    void *visit(enumerated_value_list_c *symbol);

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    /* enumerated_type_name '#' identifier */

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    // SYM_REF2(enumerated_value_c, type, value)

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    void *visit(enumerated_value_c *symbol);

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    /*  identifier ':' array_spec_init */

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    void *visit(array_type_declaration_c *symbol);

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    /* array_specification [ASSIGN array_initialization} */

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    /* array_initialization may be NULL ! */

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    void *visit(array_spec_init_c *symbol);

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    /* ARRAY '[' array_subrange_list ']' OF non_generic_type_name */

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    void *visit(array_specification_c *symbol);

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    /* helper symbol for array_specification */

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    /* array_subrange_list ',' subrange */

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    void *visit(array_subrange_list_c *symbol);

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    /* array_initialization:  '[' array_initial_elements_list ']' */

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    /* helper symbol for array_initialization */

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    /* array_initial_elements_list ',' array_initial_elements */

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    void *visit(array_initial_elements_list_c *symbol);

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    /* integer '(' [array_initial_element] ')' */

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    /* array_initial_element may be NULL ! */

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    void *visit(array_initial_elements_c *symbol);

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    /*  structure_type_name ':' structure_specification */

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    void *visit(structure_type_declaration_c *symbol);

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    /* structure_type_name ASSIGN structure_initialization */

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    /* structure_initialization may be NULL ! */

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    void *visit(initialized_structure_c *symbol);

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    /* helper symbol for structure_declaration */

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    /* structure_declaration:  STRUCT structure_element_declaration_list END_STRUCT */

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    /* structure_element_declaration_list structure_element_declaration ';' */

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    void *visit(structure_element_declaration_list_c *symbol);

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    /*  structure_element_name ':' *_spec_init */

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    void *visit(structure_element_declaration_c *symbol);

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    /* helper symbol for structure_initialization */

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    /* structure_initialization: '(' structure_element_initialization_list ')' */

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    /* structure_element_initialization_list ',' structure_element_initialization */

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    void *visit(structure_element_initialization_list_c *symbol);

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    /*  structure_element_name ASSIGN value */

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    void *visit(structure_element_initialization_c *symbol);

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    /*  string_type_name ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init */

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    /*

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     * NOTE:

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     * (Summary: Contrary to what is expected, the

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     *           string_type_declaration_c is not used to store

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     *           simple string type declarations that do not include

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     *           size limits.

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     *           For e.g.:

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     *             str1_type: STRING := "hello!"

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     *           will be stored in a simple_type_declaration_c

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     *           instead of a string_type_declaration_c.

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     *           The following:

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     *             str2_type: STRING [64] := "hello!"

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     *           will be stored in a sring_type_declaration_c

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     *

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     *           Read on for why this is done...

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     * End Summary)

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     *

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     * According to the spec, the valid construct

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     * TYPE new_str_type : STRING := "hello!"; END_TYPE

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     * has two possible routes to type_declaration...

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     *

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     * Route 1:

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     * type_declaration: single_element_type_declaration

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     * single_element_type_declaration: simple_type_declaration

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     * simple_type_declaration: identifier ':' simple_spec_init

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     * simple_spec_init: simple_specification ASSIGN constant

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     * (shift:  identifier <- 'new_str_type')

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     * simple_specification: elementary_type_name

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     * elementary_type_name: STRING

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     * (shift: elementary_type_name <- STRING)

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     * (reduce: simple_specification <- elementary_type_name)

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     * (shift: constant <- "hello!")

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     * (reduce: simple_spec_init: simple_specification ASSIGN constant)

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     * (reduce: ...)

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     *

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     *

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     * Route 2:

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     * type_declaration: string_type_declaration

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     * string_type_declaration: identifier ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init

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     * (shift:  identifier <- 'new_str_type')

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     * elementary_string_type_name: STRING

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     * (shift: elementary_string_type_name <- STRING)

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     * (shift: string_type_declaration_size <-  empty )

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     * string_type_declaration_init: ASSIGN character_string

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     * (shift: character_string <- "hello!")

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     * (reduce: string_type_declaration_init <- ASSIGN character_string)

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     * (reduce: string_type_declaration <- identifier ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init )

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     * (reduce: type_declaration <- string_type_declaration)

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     *

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     *

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     * At first glance it seems that removing route 1 would make

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     * the most sense. Unfortunately the construct 'simple_spec_init'

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     * shows up multiple times in other rules, so changing this construct

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     * would also mean changing all the rules in which it appears.

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     * I (Mario) therefore chose to remove route 2 instead. This means

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     * that the above declaration gets stored in a

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     * simple_type_declaration_c, and not in a string_type_declaration_c

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     * as would be expected!

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     */

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    /*  string_type_name ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init */

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#if 0

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SYM_REF4(string_type_declaration_c,	string_type_name,

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					elementary_string_type_name,

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					string_type_declaration_size,

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					string_type_declaration_init) /* may be == NULL! */

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#endif

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    void *visit(string_type_declaration_c *symbol);

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}; // type_initial_value_c

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