1

/*

     2

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

     3

 *

     4

 *  Copyright (C) 2003-2011  Mario de Sousa (msousa@fe.up.pt)

     5

 *  Copyright (C) 2007-2011  Laurent Bessard and Edouard Tisserant

     6

 *

     7

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

     8

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

     9

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

    10

 *  (at your option) any later version.

    11

 *

    12

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

    13

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

    14

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    15

 *  GNU General Public License for more details.

    16

 *

    17

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

    18

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

    19

 *

    20

 *

    21

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

    22

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

    23

 */

    24

    25

/*

    26

 * An IEC 61131-3 compiler.

    27

 *

    28

 * Based on the

    29

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

    30

 *

    31

 */

    32

    33

    34

/*

    35

 * Determine the default initial value of a type declaration.

    36

 *

    37

 * This is part of the 4th stage that generates

    38

 * a c++ source program equivalent to the IL and ST

    39

 * code.

    40

 */

    41

    42

/* Given a type definition declration, determine its default

    43

 * initial value. Note that types based on other types

    44

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

    45

 * to determine the initial value.

    46

 * E.g.

    47

 *  TYPE

    48

 *    A_t : INT := 10;

    49

 *    B_t : A_t := 20;

    50

 *    C_t : B_t;

    51

 *    D_t : C_t := 40;

    52

 *  END_TYPE

    53

 * Where the default initial value for C_t is 20!

    54

 */

    55

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

    56

 *       this class of object. This class

    57

 *       is therefore a singleton.

    58

 */

    59

    60

class type_initial_value_c : public null_visitor_c {

    61

    62

  public:

    63

    static symbol_c *get(symbol_c *type);

    64

    65

  private:

    66

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

    67

    static real_c		*real_0;

    68

    static integer_c		*integer_0, *integer_1;

    69

    static boolean_literal_c	*bool_0;

    70

    static date_literal_c	*date_literal_0;

    71

    static daytime_c		*daytime_literal_0;

    72

    static duration_c		*time_0;

    73

    static date_c		*date_0;

    74

    static time_of_day_c	*tod_0;

    75

    static date_and_time_c	*dt_0;

    76

    static single_byte_character_string_c *string_0;

    77

    static double_byte_character_string_c *wstring_0;

    78

    79

  protected:

    80

    type_initial_value_c(void);

    81

    82

  private:

    83

    static type_initial_value_c *_instance;

    84

    static type_initial_value_c *instance(void);

    85

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

    86

    87

  private:

    88

    void *visit(identifier_c *type_name);

    89

    90

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

    91

    /* B 1.3.1 - Elementary Data Types */

    92

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

    93

    void *visit(time_type_name_c *symbol);

    94

    void *visit(bool_type_name_c *symbol);

    95

    void *visit(sint_type_name_c *symbol);

    96

    void *visit(int_type_name_c *symbol);

    97

    void *visit(dint_type_name_c *symbol);

    98

    void *visit(lint_type_name_c *symbol);

    99

    void *visit(usint_type_name_c *symbol);

   100

    void *visit(uint_type_name_c *symbol);

   101

    void *visit(udint_type_name_c *symbol);

   102

    void *visit(ulint_type_name_c *symbol);

   103

    void *visit(real_type_name_c *symbol);

   104

    void *visit(lreal_type_name_c *symbol);

   105

    void *visit(date_type_name_c *symbol);

   106

    void *visit(tod_type_name_c *symbol);

   107

    void *visit(dt_type_name_c *symbol);

   108

    void *visit(byte_type_name_c *symbol);

   109

    void *visit(word_type_name_c *symbol);

   110

    void *visit(dword_type_name_c *symbol);

   111

    void *visit(lword_type_name_c *symbol);

   112

    void *visit(string_type_name_c *symbol);

   113

    void *visit(wstring_type_name_c *symbol);

   114

   115

    void *visit(safetime_type_name_c *symbol);

   116

    void *visit(safebool_type_name_c *symbol);

   117

    void *visit(safesint_type_name_c *symbol);

   118

    void *visit(safeint_type_name_c *symbol);

   119

    void *visit(safedint_type_name_c *symbol);

   120

    void *visit(safelint_type_name_c *symbol);

   121

    void *visit(safeusint_type_name_c *symbol);

   122

    void *visit(safeuint_type_name_c *symbol);

   123

    void *visit(safeudint_type_name_c *symbol);

   124

    void *visit(safeulint_type_name_c *symbol);

   125

    void *visit(safereal_type_name_c *symbol);

   126

    void *visit(safelreal_type_name_c *symbol);

   127

    void *visit(safedate_type_name_c *symbol);

   128

    void *visit(safetod_type_name_c *symbol);

   129

    void *visit(safedt_type_name_c *symbol);

   130

    void *visit(safebyte_type_name_c *symbol);

   131

    void *visit(safeword_type_name_c *symbol);

   132

    void *visit(safedword_type_name_c *symbol);

   133

    void *visit(safelword_type_name_c *symbol);

   134

    void *visit(safestring_type_name_c *symbol);

   135

    void *visit(safewstring_type_name_c *symbol);

   136

   137

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

   138

    /* B 1.3.3 - Derived data types */

   139

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

   140

    /*  simple_type_name ':' simple_spec_init */

   141

    void *visit(simple_type_declaration_c *symbol);

   142

   143

    /* simple_specification ASSIGN constant */

   144

    void *visit(simple_spec_init_c *symbol);

   145

   146

    /*  subrange_type_name ':' subrange_spec_init */

   147

    void *visit(subrange_type_declaration_c *symbol);

   148

   149

    /* subrange_specification ASSIGN signed_integer */

   150

    void *visit(subrange_spec_init_c *symbol);

   151

   152

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

   153

    void *visit(subrange_specification_c *symbol);

   154

   155

    /*  signed_integer DOTDOT signed_integer */

   156

    void *visit(subrange_c *symbol);

   157

   158

    /*  enumerated_type_name ':' enumerated_spec_init */

   159

    void *visit(enumerated_type_declaration_c *symbol);

   160

   161

    /* enumerated_specification ASSIGN enumerated_value */

   162

    void *visit(enumerated_spec_init_c *symbol);

   163

   164

    /* helper symbol for enumerated_specification->enumerated_spec_init */

   165

    /* enumerated_value_list ',' enumerated_value */

   166

    void *visit(enumerated_value_list_c *symbol);

   167

   168

    /* enumerated_type_name '#' identifier */

   169

    // SYM_REF2(enumerated_value_c, type, value)

   170

    void *visit(enumerated_value_c *symbol);

   171

   172

    /*  identifier ':' array_spec_init */

   173

    void *visit(array_type_declaration_c *symbol);

   174

   175

    /* array_specification [ASSIGN array_initialization} */

   176

    /* array_initialization may be NULL ! */

   177

    void *visit(array_spec_init_c *symbol);

   178

   179

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

   180

    void *visit(array_specification_c *symbol);

   181

   182

    /* helper symbol for array_specification */

   183

    /* array_subrange_list ',' subrange */

   184

    void *visit(array_subrange_list_c *symbol);

   185

   186

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

   187

    /* helper symbol for array_initialization */

   188

    /* array_initial_elements_list ',' array_initial_elements */

   189

    void *visit(array_initial_elements_list_c *symbol);

   190

   191

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

   192

    /* array_initial_element may be NULL ! */

   193

    void *visit(array_initial_elements_c *symbol);

   194

   195

    /*  structure_type_name ':' structure_specification */

   196

    void *visit(structure_type_declaration_c *symbol);

   197

   198

    /* structure_type_name ASSIGN structure_initialization */

   199

    /* structure_initialization may be NULL ! */

   200

    void *visit(initialized_structure_c *symbol);

   201

   202

    /* helper symbol for structure_declaration */

   203

    /* structure_declaration:  STRUCT structure_element_declaration_list END_STRUCT */

   204

    /* structure_element_declaration_list structure_element_declaration ';' */

   205

    void *visit(structure_element_declaration_list_c *symbol);

   206

   207

    /*  structure_element_name ':' *_spec_init */

   208

    void *visit(structure_element_declaration_c *symbol);

   209

   210

    /* helper symbol for structure_initialization */

   211

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

   212

    /* structure_element_initialization_list ',' structure_element_initialization */

   213

    void *visit(structure_element_initialization_list_c *symbol);

   214

   215

    /*  structure_element_name ASSIGN value */

   216

    void *visit(structure_element_initialization_c *symbol);

   217

   218

    /*  string_type_name ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init */

   219

    /*

   220

     * NOTE:

   221

     * (Summary: Contrary to what is expected, the

   222

     *           string_type_declaration_c is not used to store

   223

     *           simple string type declarations that do not include

   224

     *           size limits.

   225

     *           For e.g.:

   226

     *             str1_type: STRING := "hello!"

   227

     *           will be stored in a simple_type_declaration_c

   228

     *           instead of a string_type_declaration_c.

   229

     *           The following:

   230

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

   231

     *           will be stored in a sring_type_declaration_c

   232

     *

   233

     *           Read on for why this is done...

   234

     * End Summary)

   235

     *

   236

     * According to the spec, the valid construct

   237

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

   238

     * has two possible routes to type_declaration...

   239

     *

   240

     * Route 1:

   241

     * type_declaration: single_element_type_declaration

   242

     * single_element_type_declaration: simple_type_declaration

   243

     * simple_type_declaration: identifier ':' simple_spec_init

   244

     * simple_spec_init: simple_specification ASSIGN constant

   245

     * (shift:  identifier <- 'new_str_type')

   246

     * simple_specification: elementary_type_name

   247

     * elementary_type_name: STRING

   248

     * (shift: elementary_type_name <- STRING)

   249

     * (reduce: simple_specification <- elementary_type_name)

   250

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

   251

     * (reduce: simple_spec_init: simple_specification ASSIGN constant)

   252

     * (reduce: ...)

   253

     *

   254

     *

   255

     * Route 2:

   256

     * type_declaration: string_type_declaration

   257

     * string_type_declaration: identifier ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init

   258

     * (shift:  identifier <- 'new_str_type')

   259

     * elementary_string_type_name: STRING

   260

     * (shift: elementary_string_type_name <- STRING)

   261

     * (shift: string_type_declaration_size <-  empty )

   262

     * string_type_declaration_init: ASSIGN character_string

   263

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

   264

     * (reduce: string_type_declaration_init <- ASSIGN character_string)

   265

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

   266

     * (reduce: type_declaration <- string_type_declaration)

   267

     *

   268

     *

   269

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

   270

     * the most sense. Unfortunately the construct 'simple_spec_init'

   271

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

   272

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

   273

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

   274

     * that the above declaration gets stored in a

   275

     * simple_type_declaration_c, and not in a string_type_declaration_c

   276

     * as would be expected!

   277

     */

   278

    /*  string_type_name ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init */

   279

     // SYM_REF4(string_type_declaration_c,	string_type_name,

   280

     //					elementary_string_type_name,

   281

     //					string_type_declaration_size,

   282

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

   283

    void *visit(string_type_declaration_c *symbol);

   284

}; // type_initial_value_c

   285

   286

   287