/*
* (c) 2003 Mario de Sousa
*
* Offered to the public under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
* Public License for more details.
*
* This code is made available on the understanding that it will not be
* used in safety-critical situations without a full and competent review.
*/
/*
* An IEC 61131-3 IL and ST compiler.
*
* Based on the
* FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)
*
*/
/*
* Determine the default initial value of a type declaration.
*
* This is part of the 4th stage that generates
* a c++ source program equivalent to the IL and ST
* code.
*/
/* Given a type definition declration, determine its default
* initial value. Note that types based on other types
* may have to iterate through each type it is based on
* to determine the initial value.
* E.g.
* TYPE
* A_t : INT := 10;
* B_t : A_t := 20;
* C_t : B_t;
* D_t : C_t := 40;
* END_TYPE
* Where the default initial value for C_t is 20!
*/
/* NOTE: The main program only needs one instance of
* this class of object. This class
* is therefore a singleton.
*/
class type_initial_value_c : public null_visitor_c {
private:
static type_initial_value_c *_instance;
/* constants for the default values of elementary data types... */
static real_c *real_0;
static integer_c *integer_0, *integer_1;
static boolean_literal_c *bool_0;
static date_literal_c *date_literal_0;
static daytime_c *daytime_literal_0;
static duration_c *time_0;
static date_c *date_0;
static time_of_day_c *tod_0;
static date_and_time_c *dt_0;
static single_byte_character_string_c *string_0;
static double_byte_character_string_c *wstring_0;
public:
static type_initial_value_c *instance(void);
protected:
type_initial_value_c(void);
public:
symbol_c *get(identifier_c *type_name);
private:
void *handle_type_spec(symbol_c *base_type_name, symbol_c *type_spec_init);
private:
void *visit(identifier_c *type_name);
/***********************************/
/* B 1.3.1 - Elementary Data Types */
/***********************************/
void *visit(time_type_name_c *symbol);
void *visit(bool_type_name_c *symbol);
void *visit(sint_type_name_c *symbol);
void *visit(int_type_name_c *symbol);
void *visit(dint_type_name_c *symbol);
void *visit(lint_type_name_c *symbol);
void *visit(usint_type_name_c *symbol);
void *visit(uint_type_name_c *symbol);
void *visit(udint_type_name_c *symbol);
void *visit(ulint_type_name_c *symbol);
void *visit(real_type_name_c *symbol);
void *visit(lreal_type_name_c *symbol);
void *visit(date_type_name_c *symbol);
void *visit(tod_type_name_c *symbol);
void *visit(dt_type_name_c *symbol);
void *visit(byte_type_name_c *symbol);
void *visit(word_type_name_c *symbol);
void *visit(dword_type_name_c *symbol);
void *visit(lword_type_name_c *symbol);
void *visit(string_type_name_c *symbol);
void *visit(wstring_type_name_c *symbol);
/********************************/
/* B 1.3.3 - Derived data types */
/********************************/
/* simple_type_name ':' simple_spec_init */
void *visit(simple_type_declaration_c *symbol);
/* simple_specification ASSIGN constant */
void *visit(simple_spec_init_c *symbol);
/* subrange_type_name ':' subrange_spec_init */
void *visit(subrange_type_declaration_c *symbol);
/* subrange_specification ASSIGN signed_integer */
void *visit(subrange_spec_init_c *symbol);
/* integer_type_name '(' subrange')' */
void *visit(subrange_specification_c *symbol);
/* signed_integer DOTDOT signed_integer */
void *visit(subrange_c *symbol);
/* enumerated_type_name ':' enumerated_spec_init */
void *visit(enumerated_type_declaration_c *symbol);
/* enumerated_specification ASSIGN enumerated_value */
void *visit(enumerated_spec_init_c *symbol);
/* helper symbol for enumerated_specification->enumerated_spec_init */
/* enumerated_value_list ',' enumerated_value */
void *visit(enumerated_value_list_c *symbol);
/* enumerated_type_name '#' identifier */
// SYM_REF2(enumerated_value_c, type, value)
void *visit(enumerated_value_c *symbol);
/* identifier ':' array_spec_init */
void *visit(array_type_declaration_c *symbol);
/* array_specification [ASSIGN array_initialization} */
/* array_initialization may be NULL ! */
void *visit(array_spec_init_c *symbol);
/* ARRAY '[' array_subrange_list ']' OF non_generic_type_name */
void *visit(array_specification_c *symbol);
/* helper symbol for array_specification */
/* array_subrange_list ',' subrange */
void *visit(array_subrange_list_c *symbol);
/* array_initialization: '[' array_initial_elements_list ']' */
/* helper symbol for array_initialization */
/* array_initial_elements_list ',' array_initial_elements */
void *visit(array_initial_elements_list_c *symbol);
/* integer '(' [array_initial_element] ')' */
/* array_initial_element may be NULL ! */
void *visit(array_initial_elements_c *symbol);
/* structure_type_name ':' structure_specification */
void *visit(structure_type_declaration_c *symbol);
/* structure_type_name ASSIGN structure_initialization */
/* structure_initialization may be NULL ! */
void *visit(initialized_structure_c *symbol);
/* helper symbol for structure_declaration */
/* structure_declaration: STRUCT structure_element_declaration_list END_STRUCT */
/* structure_element_declaration_list structure_element_declaration ';' */
void *visit(structure_element_declaration_list_c *symbol);
/* structure_element_name ':' *_spec_init */
void *visit(structure_element_declaration_c *symbol);
/* helper symbol for structure_initialization */
/* structure_initialization: '(' structure_element_initialization_list ')' */
/* structure_element_initialization_list ',' structure_element_initialization */
void *visit(structure_element_initialization_list_c *symbol);
/* structure_element_name ASSIGN value */
void *visit(structure_element_initialization_c *symbol);
/* string_type_name ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init */
/*
* NOTE:
* (Summary: Contrary to what is expected, the
* string_type_declaration_c is not used to store
* simple string type declarations that do not include
* size limits.
* For e.g.:
* str1_type: STRING := "hello!"
* will be stored in a simple_type_declaration_c
* instead of a string_type_declaration_c.
* The following:
* str2_type: STRING [64] := "hello!"
* will be stored in a sring_type_declaration_c
*
* Read on for why this is done...
* End Summary)
*
* According to the spec, the valid construct
* TYPE new_str_type : STRING := "hello!"; END_TYPE
* has two possible routes to type_declaration...
*
* Route 1:
* type_declaration: single_element_type_declaration
* single_element_type_declaration: simple_type_declaration
* simple_type_declaration: identifier ':' simple_spec_init
* simple_spec_init: simple_specification ASSIGN constant
* (shift: identifier <- 'new_str_type')
* simple_specification: elementary_type_name
* elementary_type_name: STRING
* (shift: elementary_type_name <- STRING)
* (reduce: simple_specification <- elementary_type_name)
* (shift: constant <- "hello!")
* (reduce: simple_spec_init: simple_specification ASSIGN constant)
* (reduce: ...)
*
*
* Route 2:
* type_declaration: string_type_declaration
* string_type_declaration: identifier ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init
* (shift: identifier <- 'new_str_type')
* elementary_string_type_name: STRING
* (shift: elementary_string_type_name <- STRING)
* (shift: string_type_declaration_size <- empty )
* string_type_declaration_init: ASSIGN character_string
* (shift: character_string <- "hello!")
* (reduce: string_type_declaration_init <- ASSIGN character_string)
* (reduce: string_type_declaration <- identifier ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init )
* (reduce: type_declaration <- string_type_declaration)
*
*
* At first glance it seems that removing route 1 would make
* the most sense. Unfortunately the construct 'simple_spec_init'
* shows up multiple times in other rules, so changing this construct
* would also mean changing all the rules in which it appears.
* I (Mario) therefore chose to remove route 2 instead. This means
* that the above declaration gets stored in a
* simple_type_declaration_c, and not in a string_type_declaration_c
* as would be expected!
*/
/* string_type_name ':' elementary_string_type_name string_type_declaration_size string_type_declaration_init */
#if 0
SYM_REF4(string_type_declaration_c, string_type_name,
elementary_string_type_name,
string_type_declaration_size,
string_type_declaration_init) /* may be == NULL! */
#endif
void *visit(string_type_declaration_c *symbol);
}; // type_initial_value_c