/****************************************************************************
* fsm2num.c
* David Boozer
* (v1.0) March 30, 1999
* (v1.1) April 28, 2000
* 07 November 2007 (modified)
*****************************************************************************
* Translate finite state machine representation of a Turing machine into
* Turing number representation of Turing machine.
****************************************************************************/

#include <stdio.h>

#define NUM 1
#define ARW 2
#define RL  3

FILE *input_file;

int line_num = 1;
int token_val;
int lookahead;

void syntax_error () {
  fprintf (stderr, "Error: syntax error in line %d\n", line_num);
  exit (0);
}

int next_token () {
  char t;
  
  while (1) {
    t = getc (input_file);
    if (t == ' ' || t == '\t') ;
    else if (t == '\n') line_num++;
    else if (t == ';') {
      do
	t = getc (input_file);
      while (t != '\n' && t != EOF);
      line_num++;
    }
    else if (isdigit(t)) {
      ungetc (t, input_file);
      fscanf (input_file, "%d", &token_val);
      return NUM;
    }
    else if (t == '-') {
      if (getc (input_file) != '-') syntax_error ();
      if (getc (input_file) != '>') syntax_error ();
      return ARW;
    }
    else if (t == 'R' || t == 'L') {
      token_val = t;
      return RL;
    }
    else if (t == EOF)
      return EOF;
    else
      syntax_error ();
  }
}

void match (int token) {
  if (lookahead == token) lookahead = next_token ();
  else syntax_error ();
}

int match_bit () {
  int bit;

  bit = token_val;
  match (NUM);
  if (bit != 0 && bit != 1) syntax_error ();
  return bit;
}

void parse () {
  static int next_index = 2;
  int n, index, bit;
  int i, num_bits;

  n = token_val;
  match (NUM);
  bit = match_bit ();
  index = n<<1 | bit;
  if (index != next_index++) {
    fprintf (stderr, "Error: fsm entry skipped in line %d\n", line_num);
    exit (0);
  }

  match (ARW);
  n = token_val;
  match (NUM);

  for (i = n, num_bits = 0; i > 0; i >>= 1, num_bits++);
  for (i = num_bits-1; i >= 0; i--) printf ("%s", (n>>i & 1) ? "100" : "10");

  bit = match_bit ();

  if (bit == 0 && token_val == 'R') printf ("1100");
  if (bit == 1 && token_val == 'R') printf ("11000");
  if (bit == 0 && token_val == 'L') printf ("110000");
  if (bit == 1 && token_val == 'L') printf ("1100000");

  match (RL);
}

int main (int argc, char *argv[]) {
  if (argc != 2) {
    fprintf (stderr, "Syntax: fsm2num <input file>\n");
    exit (0);
  }

  input_file = fopen (argv[1], "r");
  if (input_file == NULL) {
    fprintf (stderr, "Error reading from file: %s\n", argv[1]);
    exit (0);
  }

  lookahead = next_token ();
  while (lookahead != EOF) parse ();

  printf ("111\n");

  return 0;
}