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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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//#include <stdio.h>  /* required for NULL */

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//#include <string>

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//#include <iostream>

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//#include "../../util/symtable.hh"

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//#include "generate_c.hh"

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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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      if (_instance != NULL)

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        return _instance;

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      _instance = new type_initial_value_c;

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      real_0 = new real_c("0");

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      integer_0 = new integer_c("0");

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      integer_1 = new integer_c("1");

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      bool_0 = new boolean_literal_c(new bool_type_name_c(),new boolean_false_c());

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      /* FIXME: Our current implementation only allows dates from 1970 onwards,

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       * but the standard defines the date 0001-01-01 as the default value

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       * for the DATE data type. Untill we fix our implementation, we use 1970-01-01

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       * as our default value!!

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       */

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//      date_literal_0 =  new date_literal_c(integer_1, integer_1, integer_1);

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      date_literal_0 =  new date_literal_c(new integer_c("1970"), integer_1, integer_1);

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      daytime_literal_0 = new daytime_c(integer_0, integer_0, real_0);

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      time_0 = new duration_c(NULL, new seconds_c(integer_0, NULL));  // T#0S

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      date_0 = new date_c(date_literal_0);  //  D#0001-01-01

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      tod_0 = new time_of_day_c(daytime_literal_0);  //  TOD#00:00:00

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      dt_0 = new date_and_time_c(date_literal_0, daytime_literal_0);  //  DT#0001-01-01-00:00:00

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      string_0  = new single_byte_character_string_c("''");

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      wstring_0 = new double_byte_character_string_c("\"\"");

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      return _instance;

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    }

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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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      TRACE("type_initial_value_c::get(): called ");

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      return (symbol_c *)type_name->accept(*this);

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    }

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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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      if (type_spec_init != NULL)

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         return type_spec_init;

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       /* no initial value specified, so we return

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       * the initial value of the type this type is based on...

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        */

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      return base_type_name->accept(*this);

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    }

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  public:

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    void *visit(identifier_c *type_name) {

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      /* look up the type declaration... */

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      symbol_c *type_decl = type_symtable.find_value(type_name);

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      if (type_decl == type_symtable.end_value())

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        /* Type declaration not found!! */

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	/* NOTE: Variables declared out of function block 'data types',

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	 *    for eg:  VAR  timer: TON; END_VAR

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	 * do not have a default value, so (TON) will never be found in the

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	 * type symbol table. This means we cannot simply consider this

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	 * an error and abort, but must rather return a NULL.

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	 */

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	return NULL;

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      return type_decl->accept(*this);

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    }

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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)	{return (void *)time_0;}

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    void *visit(bool_type_name_c *symbol)	{return (void *)bool_0;}

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    void *visit(sint_type_name_c *symbol)	{return (void *)integer_0;}

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    void *visit(int_type_name_c *symbol)	{return (void *)integer_0;}

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    void *visit(dint_type_name_c *symbol)	{return (void *)integer_0;}

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    void *visit(lint_type_name_c *symbol)	{return (void *)integer_0;}

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    void *visit(usint_type_name_c *symbol)	{return (void *)integer_0;}

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    void *visit(uint_type_name_c *symbol)	{return (void *)integer_0;}

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    void *visit(udint_type_name_c *symbol)	{return (void *)integer_0;}

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    void *visit(ulint_type_name_c *symbol)	{return (void *)integer_0;}

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    void *visit(real_type_name_c *symbol)	{return (void *)real_0;}

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    void *visit(lreal_type_name_c *symbol)	{return (void *)real_0;}

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    void *visit(date_type_name_c *symbol)	{return (void *)date_0;}

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    void *visit(tod_type_name_c *symbol)	{return (void *)tod_0;}

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    void *visit(dt_type_name_c *symbol)		{return (void *)dt_0;}

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    void *visit(byte_type_name_c *symbol)	{return (void *)integer_0;}

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    void *visit(word_type_name_c *symbol)	{return (void *)integer_0;}

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    void *visit(dword_type_name_c *symbol)	{return (void *)integer_0;}

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    void *visit(lword_type_name_c *symbol)	{return (void *)integer_0;}

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    void *visit(string_type_name_c *symbol)	{return (void *)string_0;}

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    void *visit(wstring_type_name_c *symbol)	{return (void *)wstring_0;}

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

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    }

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/* simple_specification ASSIGN constant */

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    void *visit(simple_spec_init_c *symbol) {

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      return handle_type_spec(symbol->simple_specification, symbol->constant);

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    }

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

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    }

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/* subrange_specification ASSIGN signed_integer */

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    void *visit(subrange_spec_init_c *symbol) {

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      return handle_type_spec(symbol->subrange_specification, symbol->signed_integer);

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    }

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

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    void *visit(subrange_specification_c *symbol) {

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     /* if no initial value explicitly given, then use the lowest value of the subrange */

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      if (symbol->subrange != NULL)

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

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      else

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

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    }

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/*  signed_integer DOTDOT signed_integer */

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    void *visit(subrange_c *symbol)	{return symbol->lower_limit;}

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

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    }

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/* enumerated_specification ASSIGN enumerated_value */

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    void *visit(enumerated_spec_init_c *symbol) {

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      return handle_type_spec(symbol->enumerated_specification, symbol->enumerated_value);

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    }

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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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     /* if no initial value explicitly given, then use the lowest value of the subrange */

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      return (void *)symbol->elements[0];

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    }

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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)	{ERROR; return NULL;}

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/*  identifier ':' array_spec_init */

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    void *visit(array_type_declaration_c *symbol) {

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

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    }

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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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      return handle_type_spec(symbol->array_specification, symbol->array_initialization);

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    }

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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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      symbol_c *init_value = (symbol_c *)symbol->non_generic_type_name->accept(*this);

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      /* Now build a array_initial_elements_list_c list, and populate it

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       * with 1 element of the array_initial_elements_c class

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       */

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      /* The array_initial_elements_c will contain a reference to the init_value,

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       * and another constant representing the number of elements in the array.

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       * In essence, we are building the equivilant of the following ST/IL code:

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       *    New_array_t : ARRAY [1..30, 51..60] of INT := [40(XXX)];

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       * from the user given code

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       *    New_array_t : ARRAY [1..30, 51..60] of INT;

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       * and replacing XXX with the default initial value of INT.

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       */

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      /* now we need to determine the number of elements in the array... */

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      /* Easier said than done, as the array may have a list of subranges, as in the

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       * example given above!!

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       */

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      /* TODO !!!!!*/

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      /* For now, just assume an array with 1 element.

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       * I (Mario) want to finish off this part of the code before getting boged down

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       * in something else...

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       */

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	// NOTE: We are leaking memory, as the integer will never get free'd!!

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      integer_c *integer = new integer_c("1");

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	// NOTE: We are leaking memory, as the array_initial_elements will never get free'd!!

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      array_initial_elements_c *array_initial_elements = new array_initial_elements_c(integer, init_value);

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	// NOTE: We are leaking memory, as the array_initial_elements_list will never get free'd!!

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      array_initial_elements_list_c *array_initial_elements_list  = new array_initial_elements_list_c();

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      array_initial_elements_list->add_element(array_initial_elements);

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      return array_initial_elements_list;

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    }

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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)	{ERROR; return NULL;}

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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)	{ERROR; return NULL;}

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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)	{ERROR; return NULL;}

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    /* TODO: from this point forward... */

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/*  structure_type_name ':' structure_specification */

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    void *visit(structure_type_declaration_c *symbol) {return NULL;}

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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)	{return NULL;}

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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)	{return NULL;}

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/*  structure_element_name ':' *_spec_init */

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    void *visit(structure_element_declaration_c *symbol)	{return NULL;}

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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)	{return NULL;}

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/*  structure_element_name ASSIGN value */

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    void *visit(structure_element_initialization_c *symbol)	{return NULL;}

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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)	{return NULL;}

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};

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type_initial_value_c	*type_initial_value_c::_instance = NULL;

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real_c			*type_initial_value_c::real_0 = NULL;

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integer_c		*type_initial_value_c::integer_0 = NULL;

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integer_c		*type_initial_value_c::integer_1 = NULL;

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boolean_literal_c	*type_initial_value_c::bool_0 = NULL;

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date_literal_c	*type_initial_value_c::date_literal_0 = NULL;

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daytime_c	*type_initial_value_c::daytime_literal_0 = NULL;

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duration_c	*type_initial_value_c::time_0 = NULL;

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date_c	*type_initial_value_c::date_0 = NULL;

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time_of_day_c	*type_initial_value_c::tod_0 = NULL;

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date_and_time_c	*type_initial_value_c::dt_0 = NULL;

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single_byte_character_string_c *type_initial_value_c::string_0 = NULL;

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double_byte_character_string_c *type_initial_value_c::wstring_0 = NULL;

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