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... */

    77

    static single_byte_character_string_c *string_0;

    78

    static double_byte_character_string_c *wstring_0;

    79

    80

  protected:

    81

    type_initial_value_c(void);

    82

    83

  private:

    84

    static type_initial_value_c *_instance;

    85

    static type_initial_value_c *instance(void);

    86

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

    87

    88

  private:

    89

    void *visit(identifier_c *type_name);

    90

    91

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

    92

    /* B 1.3.1 - Elementary Data Types */

    93

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

    94

    void *visit(time_type_name_c *symbol);

    95

    void *visit(bool_type_name_c *symbol);

    96

    void *visit(sint_type_name_c *symbol);

    97

    void *visit(int_type_name_c *symbol);

    98

    void *visit(dint_type_name_c *symbol);

    99

    void *visit(lint_type_name_c *symbol);

   100

    void *visit(usint_type_name_c *symbol);

   101

    void *visit(uint_type_name_c *symbol);

   102

    void *visit(udint_type_name_c *symbol);

   103

    void *visit(ulint_type_name_c *symbol);

   104

    void *visit(real_type_name_c *symbol);

   105

    void *visit(lreal_type_name_c *symbol);

   106

    void *visit(date_type_name_c *symbol);

   107

    void *visit(tod_type_name_c *symbol);

   108

    void *visit(dt_type_name_c *symbol);

   109

    void *visit(byte_type_name_c *symbol);

   110

    void *visit(word_type_name_c *symbol);

   111

    void *visit(dword_type_name_c *symbol);

   112

    void *visit(lword_type_name_c *symbol);

   113

    void *visit(string_type_name_c *symbol);

   114

    void *visit(wstring_type_name_c *symbol);

   115

   116

    void *visit(safetime_type_name_c *symbol);

   117

    void *visit(safebool_type_name_c *symbol);

   118

    void *visit(safesint_type_name_c *symbol);

   119

    void *visit(safeint_type_name_c *symbol);

   120

    void *visit(safedint_type_name_c *symbol);

   121

    void *visit(safelint_type_name_c *symbol);

   122

    void *visit(safeusint_type_name_c *symbol);

   123

    void *visit(safeuint_type_name_c *symbol);

   124

    void *visit(safeudint_type_name_c *symbol);

   125

    void *visit(safeulint_type_name_c *symbol);

   126

    void *visit(safereal_type_name_c *symbol);

   127

    void *visit(safelreal_type_name_c *symbol);

   128

    void *visit(safedate_type_name_c *symbol);

   129

    void *visit(safetod_type_name_c *symbol);

   130

    void *visit(safedt_type_name_c *symbol);

   131

    void *visit(safebyte_type_name_c *symbol);

   132

    void *visit(safeword_type_name_c *symbol);

   133

    void *visit(safedword_type_name_c *symbol);

   134

    void *visit(safelword_type_name_c *symbol);

   135

    void *visit(safestring_type_name_c *symbol);

   136

    void *visit(safewstring_type_name_c *symbol);

   137

   138

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

   139

    /* B 1.3.3 - Derived data types */

   140

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

   141

    /*  simple_type_name ':' simple_spec_init */

   142

    void *visit(simple_type_declaration_c *symbol);

   143

   144

    /* simple_specification ASSIGN constant */

   145

    void *visit(simple_spec_init_c *symbol);

   146

   147

    /*  subrange_type_name ':' subrange_spec_init */

   148

    void *visit(subrange_type_declaration_c *symbol);

   149

   150

    /* subrange_specification ASSIGN signed_integer */

   151

    void *visit(subrange_spec_init_c *symbol);

   152

   153

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

   154

    void *visit(subrange_specification_c *symbol);

   155

   156

    /*  signed_integer DOTDOT signed_integer */

   157

    void *visit(subrange_c *symbol);

   158

   159

    /*  enumerated_type_name ':' enumerated_spec_init */

   160

    void *visit(enumerated_type_declaration_c *symbol);

   161

   162

    /* enumerated_specification ASSIGN enumerated_value */

   163

    void *visit(enumerated_spec_init_c *symbol);

   164

   165

    /* helper symbol for enumerated_specification->enumerated_spec_init */

   166

    /* enumerated_value_list ',' enumerated_value */

   167

    void *visit(enumerated_value_list_c *symbol);

   168

   169

    /* enumerated_type_name '#' identifier */

   170

    // SYM_REF2(enumerated_value_c, type, value)

   171

    void *visit(enumerated_value_c *symbol);

   172

   173

    /*  identifier ':' array_spec_init */

   174

    void *visit(array_type_declaration_c *symbol);

   175

   176

    /* array_specification [ASSIGN array_initialization} */

   177

    /* array_initialization may be NULL ! */

   178

    void *visit(array_spec_init_c *symbol);

   179

   180

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

   181

    void *visit(array_specification_c *symbol);

   182

   183

    /* helper symbol for array_specification */

   184

    /* array_subrange_list ',' subrange */

   185

    void *visit(array_subrange_list_c *symbol);

   186

   187

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

   188

    /* helper symbol for array_initialization */

   189

    /* array_initial_elements_list ',' array_initial_elements */

   190

    void *visit(array_initial_elements_list_c *symbol);

   191

   192

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

   193

    /* array_initial_element may be NULL ! */

   194

    void *visit(array_initial_elements_c *symbol);

   195

   196

    /*  structure_type_name ':' structure_specification */

   197

    void *visit(structure_type_declaration_c *symbol);

   198

   199

    /* structure_type_name ASSIGN structure_initialization */

   200

    /* structure_initialization may be NULL ! */

   201

    void *visit(initialized_structure_c *symbol);

   202

   203

    /* helper symbol for structure_declaration */

   204

    /* structure_declaration:  STRUCT structure_element_declaration_list END_STRUCT */

   205

    /* structure_element_declaration_list structure_element_declaration ';' */

   206

    void *visit(structure_element_declaration_list_c *symbol);

   207

   208

    /*  structure_element_name ':' *_spec_init */

   209

    void *visit(structure_element_declaration_c *symbol);

   210

   211

    /* helper symbol for structure_initialization */

   212

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

   213

    /* structure_element_initialization_list ',' structure_element_initialization */

   214

    void *visit(structure_element_initialization_list_c *symbol);

   215

   216

    /*  structure_element_name ASSIGN value */

   217

    void *visit(structure_element_initialization_c *symbol);

   218

   219

    /*  string_type_name ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init */

   220

    /*

   221

     * NOTE:

   222

     * (Summary: Contrary to what is expected, the

   223

     *           string_type_declaration_c is not used to store

   224

     *           simple string type declarations that do not include

   225

     *           size limits.

   226

     *           For e.g.:

   227

     *             str1_type: STRING := "hello!"

   228

     *           will be stored in a simple_type_declaration_c

   229

     *           instead of a string_type_declaration_c.

   230

     *           The following:

   231

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

   232

     *           will be stored in a sring_type_declaration_c

   233

     *

   234

     *           Read on for why this is done...

   235

     * End Summary)

   236

     *

   237

     * According to the spec, the valid construct

   238

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

   239

     * has two possible routes to type_declaration...

   240

     *

   241

     * Route 1:

   242

     * type_declaration: single_element_type_declaration

   243

     * single_element_type_declaration: simple_type_declaration

   244

     * simple_type_declaration: identifier ':' simple_spec_init

   245

     * simple_spec_init: simple_specification ASSIGN constant

   246

     * (shift:  identifier <- 'new_str_type')

   247

     * simple_specification: elementary_type_name

   248

     * elementary_type_name: STRING

   249

     * (shift: elementary_type_name <- STRING)

   250

     * (reduce: simple_specification <- elementary_type_name)

   251

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

   252

     * (reduce: simple_spec_init: simple_specification ASSIGN constant)

   253

     * (reduce: ...)

   254

     *

   255

     *

   256

     * Route 2:

   257

     * type_declaration: string_type_declaration

   258

     * string_type_declaration: identifier ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init

   259

     * (shift:  identifier <- 'new_str_type')

   260

     * elementary_string_type_name: STRING

   261

     * (shift: elementary_string_type_name <- STRING)

   262

     * (shift: string_type_declaration_size <-  empty )

   263

     * string_type_declaration_init: ASSIGN character_string

   264

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

   265

     * (reduce: string_type_declaration_init <- ASSIGN character_string)

   266

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

   267

     * (reduce: type_declaration <- string_type_declaration)

   268

     *

   269

     *

   270

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

   271

     * the most sense. Unfortunately the construct 'simple_spec_init'

   272

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

   273

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

   274

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

   275

     * that the above declaration gets stored in a

   276

     * simple_type_declaration_c, and not in a string_type_declaration_c

   277

     * as would be expected!

   278

     */

   279

    /*  string_type_name ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init */

   280

     // SYM_REF4(string_type_declaration_c,	string_type_name,

   281

     //					elementary_string_type_name,

   282

     //					string_type_declaration_size,

   283

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

   284

    void *visit(string_type_declaration_c *symbol);

   293

}; // type_initial_value_c

   294

   295

   296