/*
 * listas.c
 * Recursive descencent Parser for integer lists
 */
 
#include <stdio.h>
#include "tokens.h"
#include "listasGA.h"
#include "listasSEM.h"

extern int yylex();

static int prox_simb;

int da_simbolo()
{ return yylex(); } 

rec_term(int simb)
{
  if(prox_simb == simb)
    prox_simb = da_simbolo();
  else{
    fprintf(stderr, "ERROR: unexpexpected token = %d",prox_simb);
    exit(1);
  }
}


void error()
{ fprintf(stderr, "ERROR: Syntactic, near - %d", prox_simb);
  exit(2);
}


/* ----
   Parser functions declaration
   ----
*/
List rec_List();
List rec_List2();
List rec_ElemList();
List rec_ElemList2();

/* ------------------------------------------- */
/* ----
   TOKENIZER - debug only
   -----
*/

void tokenizer()
{
while(prox_simb)
  {
    printf("%d\n",prox_simb);
    prox_simb=da_simbolo();
  }
  exit(0);
}


/* ------------------------------------------- */
/* ----
   THE PARSER
   -----
*/

main()
{
  List res;

  prox_simb = da_simbolo();
  res = rec_List();
  showList(res);
  printf("\n\nSoma = %d \n\n", SumList(res));
} 


List rec_List()
{
  rec_term(OLIST);
  return( rec_List2() );
}


List rec_List2()
{
  List aux; 

  switch(prox_simb)
  {
    case CLIST: rec_term(CLIST);
                aux = cons_P0();
                break;
    case NUM:   aux = rec_ElemList();
                rec_term(CLIST);
                break;
    default: error();
  }
  return(aux);
}


List rec_ElemList()
{
  List aux;
  int  aux2;

  aux2 = lexval;
  rec_term(NUM);
  aux = rec_ElemList2();
  return( cons_P1(aux2,aux) );
}


List rec_ElemList2()
{
  List aux;
  int aux2;

  switch(prox_simb)
  {
    case CLIST: aux = cons_P0();
                break;
    case SEP:   rec_term(SEP);
                aux2 = lexval;
                rec_term(NUM);
                aux = cons_P1( aux2, rec_ElemList2() );
                break;
    default: error();
  }
  return(aux);
}