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/*

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

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 *

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 *  Copyright (C) 2012  Mario de Sousa (msousa@fe.up.pt)

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 *

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

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

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

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 *  (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,

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

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 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

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 *  GNU General Public License for more details.

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 *

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

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

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 *

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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 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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 *  Data type analysis of IL code may leave some IL instructions with an undefined datatype.

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 *  This visitor will set the datatype for all these symbols, so that all symbols have a well 

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 *  defined datatype when we reach stage4.

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 *

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 *  Example:

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 * =========

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 *

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 *  VAR 

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 *     N   : INT := 99 ;    

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 *     tonv: TON;

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 *     byte_var: BYTE;

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 *     tonv : TON;

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 *     a : BYTE;

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 *     t : time;

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 *     tod1: tod;

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 *  END_VAR

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 *  

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 * (0) --> Data type before executing forced_narrow_candidate_datatypes_c

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 * (1) --> Data type after executing 1st pass of forced_narrow_candidate_datatypes_c

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 * (2) --> Data type after executing 2nd pass of forced_narrow_candidate_datatypes_c

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 * 

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 * --- --> NULL (undefined datatype)

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 * *** --> invalid_type_name_c (invalid datatype)

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 *

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 * (0)       (1)   (2)

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 *      

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 * ---       ***   ***       CAL tonv (                          

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 *                                  PT := T#1s                   

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 *                               )                               

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 * ---       ***   ***       JMP l4                              

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 *

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 * ---       sint  sint  l0: LD  1                               

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 * ---       sint  sint      ADD 2                               

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 * --- (c)   sint  sint      CAL tonv (                          

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 *                               PT := T#1s                      

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 *                               )                               

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 *                                                               

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 * ---       sint  sint      LD  45                              

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 * --- (c)   sint  sint      ADD 45                              

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 *

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 *

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 * ---       sint  sint      LD  3                               

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 * ---       sint  sint  l1:                                     

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 * --- (c)   sint  sint  l2: ADD 4                               

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 * int       int   int       LD  5                               

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 * int       int   int       ST  n                               

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 * int       int   int       JMP l3                              

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 *                                                               

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 * --- (d)   ---   sint      LD  5                               

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 * --- (d)   ---   sint      SUB 6                               

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 * --- (d)   sint  sint      JMP l1                              

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 *

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 * ---       bool  bool      LD  FALSE                           

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 * ---       bool  bool      NOT                                 

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 * --- (b)   bool  bool      RET                                 

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 *

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 * int       int   int   l3:                                     

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 * int       int   int       ST  n                               

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 * --- (b)   int   int       RET                                 

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 *

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 * ---       ***   ***   l4:                                     

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 * ---       ***   ***       CAL tonv (                          

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 *                                  PT := T#1s                   

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 *                               )                               

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 * --- (a)   ***   ***       JMP l0                              

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 * --- (b)   byte  byte      LD  88                              

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 *

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 *

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 *   

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 */

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#include "forced_narrow_candidate_datatypes.hh"

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#include "datatype_functions.hh"

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/* set to 1 to see debug info during execution */

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static int debug = 0;

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forced_narrow_candidate_datatypes_c::forced_narrow_candidate_datatypes_c(symbol_c *ignore) 

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 :narrow_candidate_datatypes_c(ignore) {

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}

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forced_narrow_candidate_datatypes_c::~forced_narrow_candidate_datatypes_c(void) {

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}

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

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/* B.2 - Language IL (Instruction List) */

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

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

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/* B 2.1 Instructions and Operands */

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

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/*| instruction_list il_instruction */

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// SYM_LIST(instruction_list_c)

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void *forced_narrow_candidate_datatypes_c::visit(instruction_list_c *symbol) {

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print_ast_c::print(symbol);

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  for(int j = 0; j < 2; j++) {

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    for(int i = symbol->n-1; i >= 0; i--) {

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      symbol->elements[i]->accept(*this);

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    }

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  }

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  /* Assert that this algorithm managed to remove all NULL datatypes! */

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  for(int i = symbol->n-1; i >= 0; i--) {

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    if (NULL == symbol->elements[i]->datatype)

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      ERROR;

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  }

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  return NULL;

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}

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/* | label ':' [il_incomplete_instruction] eol_list */

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// SYM_REF2(il_instruction_c, label, il_instruction)

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// void *visit(instruction_list_c *symbol);

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void *forced_narrow_candidate_datatypes_c::visit(il_instruction_c *symbol) {

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  if (NULL == symbol->datatype) {

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    if (symbol->candidate_datatypes.empty()) {

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      symbol->datatype = &(search_constant_type_c::invalid_type_name); // This will occur in the situations (a) in the above example

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      // return NULL; // No need to return control to the visit() method of the base class... But we do so, just to be safe (called at the end of this function)!

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    } else {

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      if (symbol->next_il_instruction.empty()) {

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        symbol->datatype = symbol->candidate_datatypes[0]; // This will occur in the situations (b) in the above example

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      } else {

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        symbol_c *next_datatype = NULL;

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        /* find the datatype of the following IL instructions (they should all be identical by now, but we don't have an assertion checking for this. */

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        for (unsigned int i=0; i < symbol->next_il_instruction.size(); i++)

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          if (NULL != symbol->next_il_instruction[i]->datatype)

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            next_datatype = symbol->next_il_instruction[i]->datatype;

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        if (get_datatype_info_c::is_type_valid(next_datatype)) {

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          /* This will occur in the following situations from the above example	   

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           *    (d)   during the second pass of this algorithm (remember, we execute this algorithm twice, because of backward JMPs!)

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           */

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          symbol->datatype = symbol->candidate_datatypes[0]; 

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        } else {

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          /* This will occur in the following situations from the above example	   

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           *    (d)   during the first pass of this algorithm (remember, we execute this algorithm twice, because of backward JMPs!)

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           */

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          // it is not possible to determine the exact situation in the current pass, so we can't do anything just yet. Leave it for the next time around!

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        }

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      }

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    }

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  }

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  /* return control to the visit() method of the base class! */

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  narrow_candidate_datatypes_c::visit(symbol);

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  return NULL;

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}

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/* | il_simple_operator [il_operand] */

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// SYM_REF2(il_simple_operation_c, il_simple_operator, il_operand)

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// void *forced_narrow_candidate_datatypes_c::visit(il_simple_operation_c *symbol)

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/* | function_name [il_operand_list] */

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/* NOTE: The parameters 'called_function_declaration' and 'extensible_param_count' are used to pass data between the stage 3 and stage 4. */

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// SYM_REF2(il_function_call_c, function_name, il_operand_list, symbol_c *called_function_declaration; int extensible_param_count;)

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// void *forced_narrow_candidate_datatypes_c::visit(il_function_call_c *symbol) 

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/* | il_expr_operator '(' [il_operand] eol_list [simple_instr_list] ')' */

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// SYM_REF3(il_expression_c, il_expr_operator, il_operand, simple_instr_list);

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// void *forced_narrow_candidate_datatypes_c::visit(il_expression_c *symbol)

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/*  il_jump_operator label */

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// SYM_REF2(il_jump_operation_c, il_jump_operator, label)

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// void *forced_narrow_candidate_datatypes_c::visit(il_jump_operation_c *symbol)

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/*   il_call_operator prev_declared_fb_name

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 * | il_call_operator prev_declared_fb_name '(' ')'

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 * | il_call_operator prev_declared_fb_name '(' eol_list ')'

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 * | il_call_operator prev_declared_fb_name '(' il_operand_list ')'

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 * | il_call_operator prev_declared_fb_name '(' eol_list il_param_list ')'

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 */

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/* NOTE: The parameter 'called_fb_declaration'is used to pass data between stage 3 and stage4 (although currently it is not used in stage 4 */

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// SYM_REF4(il_fb_call_c, il_call_operator, fb_name, il_operand_list, il_param_list, symbol_c *called_fb_declaration)

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// void *forced_narrow_candidate_datatypes_c::visit(il_fb_call_c *symbol)

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/* | function_name '(' eol_list [il_param_list] ')' */

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/* NOTE: The parameter 'called_function_declaration' is used to pass data between the stage 3 and stage 4. */

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// SYM_REF2(il_formal_funct_call_c, function_name, il_param_list, symbol_c *called_function_declaration; int extensible_param_count;)

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// void *forced_narrow_candidate_datatypes_c::visit(il_formal_funct_call_c *symbol)

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// void *visit(il_operand_list_c *symbol);

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// void *forced_narrow_candidate_datatypes_c::visit(simple_instr_list_c *symbol)

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// SYM_REF1(il_simple_instruction_c, il_simple_instruction, symbol_c *prev_il_instruction;)

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// void *forced_narrow_candidate_datatypes_c::visit(il_simple_instruction_c*symbol)

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/*

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    void *visit(il_param_list_c *symbol);

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    void *visit(il_param_assignment_c *symbol);

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    void *visit(il_param_out_assignment_c *symbol);

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 */

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