diff -r 000000000000 -r fb772792efd1 stage4/generate_cc/type_initial_value.cc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/stage4/generate_cc/type_initial_value.cc	Wed Jan 31 15:32:38 2007 +0100
@@ -0,0 +1,378 @@
+/*
+ * (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.
+ */
+
+
+
+
+//#include <stdio.h>  /* required for NULL */
+//#include <string>
+//#include <iostream>
+
+//#include "../../util/symtable.hh"
+
+//#include "generate_cc.hh"
+
+
+
+
+
+/* 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) {
+      if (_instance != NULL)
+        return _instance;
+
+      _instance = new type_initial_value_c;
+
+      real_0 = new real_c("0");
+      integer_0 = new integer_c("0");
+      integer_1 = new integer_c("1");
+      bool_0 = new boolean_literal_c(new bool_type_name_c(),new boolean_false_c());
+      /* FIXME: Our current implementation only allows dates from 1970 onwards,
+       * but the standard defines the date 0001-01-01 as the default value
+       * for the DATE data type. Untill we fix our implementation, we use 1970-01-01
+       * as our default value!!
+       */
+//      date_literal_0 =  new date_literal_c(integer_1, integer_1, integer_1);
+      date_literal_0 =  new date_literal_c(new integer_c("1970"), integer_1, integer_1);
+      daytime_literal_0 = new daytime_c(integer_0, integer_0, real_0);
+      time_0 = new duration_c(NULL, new seconds_c(integer_0, NULL));  // T#0S
+      date_0 = new date_c(date_literal_0);  //  D#0001-01-01
+      tod_0 = new time_of_day_c(daytime_literal_0);  //  TOD#00:00:00
+      dt_0 = new date_and_time_c(date_literal_0, daytime_literal_0);  //  DT#0001-01-01-00:00:00
+      string_0  = new single_byte_character_string_c("''");
+      wstring_0 = new double_byte_character_string_c("\"\"");
+
+      return _instance;
+    }
+
+  protected:
+    type_initial_value_c(void) {}
+
+  public:
+    symbol_c *get(identifier_c *type_name) {
+      TRACE("type_initial_value_c::get(): called ");
+      return (symbol_c *)type_name->accept(*this);
+    }
+
+
+  private:
+    void *handle_type_spec(symbol_c *base_type_name, symbol_c *type_spec_init) {
+      if (type_spec_init != NULL)
+         return type_spec_init;
+       /* no initial value specified, so we return
+       * the initial value of the type this type is based on...
+        */
+      return base_type_name->accept(*this);
+    }
+
+  public:
+    void *visit(identifier_c *type_name) {
+      /* look up the type declaration... */
+      symbol_c *type_decl = type_symtable.find_value(type_name);
+      if (type_decl == type_symtable.end_value())
+        /* Type declaration not found!! */
+	/* NOTE: Variables declared out of function block 'data types',
+	 *    for eg:  VAR  timer: TON; END_VAR
+	 * do not have a default value, so (TON) will never be found in the
+	 * type symbol table. This means we cannot simply consider this
+	 * an error and abort, but must rather return a NULL.
+	 */
+	return NULL;
+
+      return type_decl->accept(*this);
+    }
+
+/***********************************/
+/* B 1.3.1 - Elementary Data Types */
+/***********************************/
+    void *visit(time_type_name_c *symbol)	{return (void *)time_0;}
+    void *visit(bool_type_name_c *symbol)	{return (void *)bool_0;}
+    void *visit(sint_type_name_c *symbol)	{return (void *)integer_0;}
+    void *visit(int_type_name_c *symbol)	{return (void *)integer_0;}
+    void *visit(dint_type_name_c *symbol)	{return (void *)integer_0;}
+    void *visit(lint_type_name_c *symbol)	{return (void *)integer_0;}
+    void *visit(usint_type_name_c *symbol)	{return (void *)integer_0;}
+    void *visit(uint_type_name_c *symbol)	{return (void *)integer_0;}
+    void *visit(udint_type_name_c *symbol)	{return (void *)integer_0;}
+    void *visit(ulint_type_name_c *symbol)	{return (void *)integer_0;}
+    void *visit(real_type_name_c *symbol)	{return (void *)real_0;}
+    void *visit(lreal_type_name_c *symbol)	{return (void *)real_0;}
+    void *visit(date_type_name_c *symbol)	{return (void *)date_0;}
+    void *visit(tod_type_name_c *symbol)	{return (void *)tod_0;}
+    void *visit(dt_type_name_c *symbol)		{return (void *)dt_0;}
+    void *visit(byte_type_name_c *symbol)	{return (void *)integer_0;}
+    void *visit(word_type_name_c *symbol)	{return (void *)integer_0;}
+    void *visit(dword_type_name_c *symbol)	{return (void *)integer_0;}
+    void *visit(lword_type_name_c *symbol)	{return (void *)integer_0;}
+    void *visit(string_type_name_c *symbol)	{return (void *)string_0;}
+    void *visit(wstring_type_name_c *symbol)	{return (void *)wstring_0;}
+
+/********************************/
+/* B 1.3.3 - Derived data types */
+/********************************/
+/*  simple_type_name ':' simple_spec_init */
+    void *visit(simple_type_declaration_c *symbol) {
+      return symbol->simple_spec_init->accept(*this);
+    }
+/* simple_specification ASSIGN constant */
+    void *visit(simple_spec_init_c *symbol) {
+      return handle_type_spec(symbol->simple_specification, symbol->constant);
+    }
+/*  subrange_type_name ':' subrange_spec_init */
+    void *visit(subrange_type_declaration_c *symbol) {
+      return symbol->subrange_spec_init->accept(*this);
+    }
+/* subrange_specification ASSIGN signed_integer */
+    void *visit(subrange_spec_init_c *symbol) {
+      return handle_type_spec(symbol->subrange_specification, symbol->signed_integer);
+    }
+/*  integer_type_name '(' subrange')' */
+    void *visit(subrange_specification_c *symbol) {
+     /* if no initial value explicitly given, then use the lowest value of the subrange */
+      return symbol->subrange->accept(*this);
+    }
+/*  signed_integer DOTDOT signed_integer */
+    void *visit(subrange_c *symbol)	{return symbol->lower_limit;}
+/*  enumerated_type_name ':' enumerated_spec_init */
+    void *visit(enumerated_type_declaration_c *symbol) {
+      return symbol->enumerated_spec_init->accept(*this);
+    }
+/* enumerated_specification ASSIGN enumerated_value */
+    void *visit(enumerated_spec_init_c *symbol) {
+      return handle_type_spec(symbol->enumerated_specification, symbol->enumerated_value);
+    }
+/* helper symbol for enumerated_specification->enumerated_spec_init */
+/* enumerated_value_list ',' enumerated_value */
+    void *visit(enumerated_value_list_c *symbol) {
+     /* if no initial value explicitly given, then use the lowest value of the subrange */
+      return (void *)symbol->elements[0];
+    }
+/* enumerated_type_name '#' identifier */
+// SYM_REF2(enumerated_value_c, type, value)
+    void *visit(enumerated_value_c *symbol)	{ERROR; return NULL;}
+/*  identifier ':' array_spec_init */
+    void *visit(array_type_declaration_c *symbol) {
+      return symbol->array_spec_init->accept(*this);
+    }
+/* array_specification [ASSIGN array_initialization} */
+/* array_initialization may be NULL ! */
+    void *visit(array_spec_init_c *symbol) {
+      return handle_type_spec(symbol->array_specification, symbol->array_initialization);
+    }
+/* ARRAY '[' array_subrange_list ']' OF non_generic_type_name */
+    void *visit(array_specification_c *symbol)	{
+      symbol_c *init_value = (symbol_c *)symbol->non_generic_type_name->accept(*this);
+
+      /* Now build a array_initial_elements_list_c list, and populate it
+       * with 1 element of the array_initial_elements_c class
+       */
+      /* The array_initial_elements_c will contain a reference to the init_value,
+       * and another constant representing the number of elements in the array.
+       * In essence, we are building the equivilant of the following ST/IL code:
+       *    New_array_t : ARRAY [1..30, 51..60] of INT := [40(XXX)];
+       * from the user given code
+       *    New_array_t : ARRAY [1..30, 51..60] of INT;
+       * and replacing XXX with the default initial value of INT.
+       */
+      /* now we need to determine the number of elements in the array... */
+      /* Easier said than done, as the array may have a list of subranges, as in the
+       * example given above!!
+       */
+      /* TODO !!!!!*/
+      /* For now, just assume an array with 1 element.
+       * I (Mario) want to finish off this part of the code before getting boged down
+       * in something else...
+       */
+	// NOTE: We are leaking memory, as the integer will never get free'd!!
+      integer_c *integer = new integer_c("1");
+	// NOTE: We are leaking memory, as the array_initial_elements will never get free'd!!
+      array_initial_elements_c *array_initial_elements = new array_initial_elements_c(integer, init_value);
+	// NOTE: We are leaking memory, as the array_initial_elements_list will never get free'd!!
+      array_initial_elements_list_c *array_initial_elements_list  = new array_initial_elements_list_c();
+      array_initial_elements_list->add_element(array_initial_elements);
+      return (void *)array_initial_elements_list;
+    }
+/* helper symbol for array_specification */
+/* array_subrange_list ',' subrange */
+    void *visit(array_subrange_list_c *symbol)	{ERROR; return NULL;}
+/* 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)	{ERROR; return NULL;}
+/* integer '(' [array_initial_element] ')' */
+/* array_initial_element may be NULL ! */
+    void *visit(array_initial_elements_c *symbol)	{ERROR; return NULL;}
+
+
+
+    /* TODO: from this point forward... */
+
+/*  structure_type_name ':' structure_specification */
+    void *visit(structure_type_declaration_c *symbol) {return NULL;}
+/* structure_type_name ASSIGN structure_initialization */
+/* structure_initialization may be NULL ! */
+    void *visit(initialized_structure_c *symbol)	{return NULL;}
+/* 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)	{return NULL;}
+/*  structure_element_name ':' *_spec_init */
+    void *visit(structure_element_declaration_c *symbol)	{return NULL;}
+/* 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)	{return NULL;}
+/*  structure_element_name ASSIGN value */
+    void *visit(structure_element_initialization_c *symbol)	{return NULL;}
+/*  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)	{return NULL;}
+};
+
+type_initial_value_c	*type_initial_value_c::_instance = NULL;
+real_c			*type_initial_value_c::real_0 = NULL;
+integer_c		*type_initial_value_c::integer_0 = NULL;
+integer_c		*type_initial_value_c::integer_1 = NULL;
+boolean_literal_c	*type_initial_value_c::bool_0 = NULL;
+date_literal_c	*type_initial_value_c::date_literal_0 = NULL;
+daytime_c	*type_initial_value_c::daytime_literal_0 = NULL;
+duration_c	*type_initial_value_c::time_0 = NULL;
+date_c	*type_initial_value_c::date_0 = NULL;
+time_of_day_c	*type_initial_value_c::tod_0 = NULL;
+date_and_time_c	*type_initial_value_c::dt_0 = NULL;
+single_byte_character_string_c *type_initial_value_c::string_0 = NULL;
+double_byte_character_string_c *type_initial_value_c::wstring_0 = NULL;
+
+
+
+
+
+