1

/*

     2

 * (c) 2003 Mario de Sousa

     3

 *

     4

 * Offered to the public under the terms of the GNU General Public License

     5

 * as published by the Free Software Foundation; either version 2 of the

     6

 * License, or (at your option) any later version.

     7

 *

     8

 * This program is distributed in the hope that it will be useful, but

     9

 * WITHOUT ANY WARRANTY; without even the implied warranty of

    10

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General

    11

 * Public License for more details.

    12

 *

    13

 * This code is made available on the understanding that it will not be

    14

 * used in safety-critical situations without a full and competent review.

    15

 */

    16

    17

/*

    18

 * An IEC 61131-3 IL and ST compiler.

    19

 *

    20

 * Based on the

    21

 * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)

    22

 *

    23

 */

    24

    25

    26

/* Decomposes a variable instance name into its constituents,

    27

 * example:

    28

 *    window.points[1].coordinate.x

    29

 *

    30

 *  will succesfully return

    31

 *        - window

    32

 *        - points

    33

 *        - coordinate

    34

 *        - x

    35

 * on succesive calls to decompose_var_instance_name_c::next_part()

    36

 */

    37

    38

    39

    40

#include "decompose_var_instance_name.hh"

    41

    42

decompose_var_instance_name_c::decompose_var_instance_name_c(symbol_c *variable_instance_name) {

    43

  variable_name = variable_instance_name;

    44

  next_variable_name = NULL;

    45

  current_recursive_variable_name = NULL;

    46

  previously_returned_variable_name = NULL;

    47

}

    48

    49

symbol_c *decompose_var_instance_name_c::next_part(bool increment) {

    50

  /* We must always start from the top!

    51

   * See note in the structured_variable_c visitor

    52

   * to understand why...

    53

   */

    54

  symbol_c *res = (symbol_c *)variable_name->accept(*this);

    55

  if (increment)

    56

    next_variable_name = current_recursive_variable_name;

    57

    58

  if (previously_returned_variable_name == res)

    59

	  return NULL;

    60

  if (increment)

    61

    previously_returned_variable_name = res;

    62

  return res;

    63

}

    64

    65

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

    66

/* B.1 - Common elements */

    67

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

    68

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

    69

/* B 1.1 - Letters, digits and identifiers */

    70

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

    71

/* sometimes (e.g. FB calls) the name of the variable is stored directly in an identifier_c object */

    72

void *decompose_var_instance_name_c::visit(identifier_c *symbol) {return (void *)symbol;}

    73

    74

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

    75

/* B 1.4 - Variables */

    76

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

    77

void *decompose_var_instance_name_c::visit(symbolic_variable_c *symbol) {return (void *)(symbol->var_name);}

    78

    79

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

    80

/* B.1.4.1   Directly Represented Variables */

    81

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

    82

void *decompose_var_instance_name_c::visit(direct_variable_c *symbol) {return (void *)symbol;}

    83

    84

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

    85

/* B.1.4.2   Multi-element Variables */

    86

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

    87

/*  subscripted_variable '[' subscript_list ']' */

    88

// SYM_REF2(array_variable_c, subscripted_variable, subscript_list)

    89

void *decompose_var_instance_name_c::visit(array_variable_c *symbol) {

    90

  /* NOTE: the subscripted_variable may itself be a structure!,

    91

   * so we must recursevily visit!

    92

   */

    93

  return symbol->subscripted_variable->accept(*this);

    94

}

    95

    96

/*  record_variable '.' field_selector */

    97

/*  WARNING: input and/or output variables of function blocks

    98

 *           may be accessed as fields of a tructured variable!

    99

 *           Code handling a structured_variable_c must take

   100

 *           this into account!

   101

 */

   102

//SYM_REF2(structured_variable_c, record_variable, field_selector)

   103

void *decompose_var_instance_name_c::visit(structured_variable_c *symbol) {

   104

  /* NOTE: The following code will not work, as structured_variable_c

   105

   *       are grouped on the left, and not on the right!

   106

   *

   107

   *       example: window.origin.x

   108

   *       will result in

   109

   *       s1 = structured_variable_c("window, "origin");

   110

   *       s2 = structured_variable_c(s1, "x");

   111

   *       AND NOT

   112

   *       s1 = structured_variable_c("origin", "x");

   113

   *       s2 = structured_variable_c("window", s1);

   114

   *

   115

   *       as the following code assumes!!

   116

   *

   117

  current_variable_name = symbol->field_selector;

   118

  return symbol->record_variable->accept(*this);

   119

   */

   120

   121

  /* The correct code, is therefore more complex... */

   122

  if (next_variable_name == symbol) {

   123

    /* NOTE: field_selector is always an identifier_c,

   124

     * so we do not have to recursevily visit it again...

   125

     * return (void *)symbol->field_selector->accept(*this);  -> NOT REQUIRED!!

   126

     */

   127

	 return (void *)symbol->field_selector;

   128

  }

   129

   130

  current_recursive_variable_name = symbol;

   131

  return symbol->record_variable->accept(*this);

   132

}

   133

   134

   135

   136