expr.c

android-w.song.android.widget

      if (op == LEQ)
	val1 = val1 <= val2;
      else if (op == GEQ)
	val1 = val1 >= val2;
      else if (op == LT)
	val1 = val1 < val2;
      else			/* (op == GT) */
	val1 = val1 > val2;
    }
  return (val1);
}

/* Left and right shifts. */
static intmax_t
expshift ()
{
  register intmax_t val1, val2;

  val1 = exp3 ();

  while ((curtok == LSH) || (curtok == RSH))
    {
      int op = curtok;

      readtok ();
      val2 = exp3 ();

      if (op == LSH)
	val1 = val1 << val2;
      else
	val1 = val1 >> val2;
    }

  return (val1);
}

static intmax_t
exp3 ()
{
  register intmax_t val1, val2;

  val1 = exp2 ();

  while ((curtok == PLUS) || (curtok == MINUS))
    {
      int op = curtok;

      readtok ();
      val2 = exp2 ();

      if (op == PLUS)
	val1 += val2;
      else if (op == MINUS)
	val1 -= val2;
    }
  return (val1);
}

static intmax_t
exp2 ()
{
  register intmax_t val1, val2;

  val1 = exppower ();

  while ((curtok == MUL) ||
	 (curtok == DIV) ||
	 (curtok == MOD))
    {
      int op = curtok;

      readtok ();

      val2 = exppower ();

      if (((op == DIV) || (op == MOD)) && (val2 == 0))
	evalerror (_("division by 0"));

      if (op == MUL)
	val1 *= val2;
      else if (op == DIV)
	val1 /= val2;
      else if (op == MOD)
	val1 %= val2;
    }
  return (val1);
}

static intmax_t
exppower ()
{
  register intmax_t val1, val2, c;

  val1 = exp1 ();
  while (curtok == POWER)
    {
      readtok ();
      val2 = exppower ();	/* exponentiation is right-associative */
      if (val2 == 0)
	return (1);
      if (val2 < 0)
	evalerror (_("exponent less than 0"));
      for (c = 1; val2--; c *= val1)
	;
      val1 = c;
    }
  return (val1);
}

static intmax_t
exp1 ()
{
  register intmax_t val;

  if (curtok == NOT)
    {
      readtok ();
      val = !exp1 ();
    }
  else if (curtok == BNOT)
    {
      readtok ();
      val = ~exp1 ();
    }
  else if (curtok == MINUS)
    {
      readtok ();
      val = - exp1 ();
    }
  else if (curtok == PLUS)
    {
      readtok ();
      val = exp1 ();
    }
  else
    val = exp0 ();

  return (val);
}

static intmax_t
exp0 ()
{
  register intmax_t val = 0, v2;
  char *vincdec;
  int stok;
  EXPR_CONTEXT ec;

  /* XXX - might need additional logic here to decide whether or not
	   pre-increment or pre-decrement is legal at this point. */
  if (curtok == PREINC || curtok == PREDEC)
    {
      stok = lasttok = curtok;
      readtok ();
      if (curtok != STR)
	/* readtok() catches this */
	evalerror (_("identifier expected after pre-increment or pre-decrement"));

      v2 = tokval + ((stok == PREINC) ? 1 : -1);
      vincdec = itos (v2);
      if (noeval == 0)
	{
	  if (curlval.ind != -1)
	    expr_bind_array_element (curlval.tokstr, curlval.ind, vincdec);
	  else
	    expr_bind_variable (tokstr, vincdec);
	}
      free (vincdec);
      val = v2;

      curtok = NUM;	/* make sure --x=7 is flagged as an error */
      readtok ();
    }
  else if (curtok == LPAR)
    {
      readtok ();
      val = EXP_HIGHEST ();

      if (curtok != RPAR) /* ( */
	evalerror (_("missing `)'"));

      /* Skip over closing paren. */
      readtok ();
    }
  else if ((curtok == NUM) || (curtok == STR))
    {
      val = tokval;
      if (curtok == STR)
	{
	  SAVETOK (&ec);
	  tokstr = (char *)NULL;	/* keep it from being freed */
          noeval = 1;
          readtok ();
          stok = curtok;

	  /* post-increment or post-decrement */
 	  if (stok == POSTINC || stok == POSTDEC)
 	    {
 	      /* restore certain portions of EC */
 	      tokstr = ec.tokstr;
 	      noeval = ec.noeval;
 	      curlval = ec.lval;
 	      lasttok = STR;	/* ec.curtok */

	      v2 = val + ((stok == POSTINC) ? 1 : -1);
	      vincdec = itos (v2);
	      if (noeval == 0)
		{
		  if (curlval.ind != -1)
		    expr_bind_array_element (curlval.tokstr, curlval.ind, vincdec);
		  else
		    expr_bind_variable (tokstr, vincdec);
		}
	      free (vincdec);
	      curtok = NUM;	/* make sure x++=7 is flagged as an error */
 	    }
 	  else
 	    {
	      if (stok == STR)	/* free new tokstr before old one is restored */
		FREE (tokstr);
	      RESTORETOK (&ec);
 	    }

	}
	  
      readtok ();
    }
  else
    evalerror (_("syntax error: operand expected"));

  return (val);
}

static void
init_lvalue (lv)
     struct lvalue *lv;
{
  lv->tokstr = 0;
  lv->tokvar = 0;
  lv->tokval = lv->ind = -1;
}

static struct lvalue *
alloc_lvalue ()
{
  struct lvalue *lv;

  lv = xmalloc (sizeof (struct lvalue));
  init_lvalue (lv);
  return (lv);
}

static void
free_lvalue (lv)
     struct lvalue *lv;
{
  free (lv);		/* should be inlined */
}

static intmax_t
expr_streval (tok, e, lvalue)
     char *tok;
     int e;
     struct lvalue *lvalue;
{
  SHELL_VAR *v;
  char *value;
  intmax_t tval;
#if defined (ARRAY_VARS)
  arrayind_t ind;
#endif

  /* [[[[[ */
#if defined (ARRAY_VARS)
  v = (e == ']') ? array_variable_part (tok, (char **)0, (int *)0) : find_variable (tok);
#else
  v = find_variable (tok);
#endif

  if ((v == 0 || invisible_p (v)) && unbound_vars_is_error)
    {
#if defined (ARRAY_VARS)
      value = (e == ']') ? array_variable_name (tok, (char **)0, (int *)0) : tok;
#else
      value = tok;
#endif

      last_command_exit_value = EXECUTION_FAILURE;
      err_unboundvar (value);

#if defined (ARRAY_VARS)
      if (e == ']')
	FREE (value);	/* array_variable_name returns new memory */
#endif

      if (interactive_shell)
	{
	  expr_unwind ();
	  top_level_cleanup ();
	  jump_to_top_level (DISCARD);
	}
      else
	jump_to_top_level (FORCE_EOF);
    }

  ind = -1;
#if defined (ARRAY_VARS)
  /* Second argument of 0 to get_array_value means that we don't allow
     references like array[@].  In this case, get_array_value is just
     like get_variable_value in that it does not return newly-allocated
     memory or quote the results. */
  value = (e == ']') ? get_array_value (tok, 0, (int *)NULL, &ind) : get_variable_value (v);
#else
  value = get_variable_value (v);
#endif

  tval = (value && *value) ? subexpr (value) : 0;

  if (lvalue)
    {
      lvalue->tokstr = tok;	/* XXX */
      lvalue->tokval = tval;
      lvalue->tokvar = v;	/* XXX */
      lvalue->ind = ind;
    }
	  
  return (tval);
}

static int
_is_multiop (c)
     int c;
{
  switch (c)
    {
    case EQEQ:
    case NEQ:
    case LEQ:
    case GEQ:
    case LAND:
    case LOR:
    case LSH:
    case RSH:
    case OP_ASSIGN:
    case COND:
    case POWER:
    case PREINC:
    case PREDEC:
    case POSTINC:
    case POSTDEC:
      return 1;
    default:
      return 0;
    }
}

static int
_is_arithop (c)
     int c;
{
  switch (c)
    {
    case EQ:
    case GT:
    case LT:
    case PLUS:
    case MINUS:
    case MUL:
    case DIV:
    case MOD:
    case NOT:
    case LPAR:
    case RPAR:
    case BAND:
    case BOR:
    case BXOR:
    case BNOT:
      return 1;		/* operator tokens */
    case QUES:
    case COL:
    case COMMA:
      return 1;		/* questionable */
    default:
      return 0;		/* anything else is invalid */
    }
}

/* Lexical analyzer/token reader for the expression evaluator.  Reads the
   next token and puts its value into curtok, while advancing past it.
   Updates value of tp.  May also set tokval (for number) or tokstr (for
   string). */
static void
readtok ()
{
  register char *cp, *xp;
  register unsigned char c, c1;
  register int e;
  struct lvalue lval;

  /* Skip leading whitespace. */
  cp = tp;
  c = e = 0;
  while (cp && (c = *cp) && (cr_whitespace (c)))
    cp++;

  if (c)
    cp++;

  if (c == '\0')
    {
      lasttok = curtok;
      curtok = 0;
      tp = cp;
      return;
    }
  lasttp = tp = cp - 1;

  if (legal_variable_starter (c))
    {
      /* variable names not preceded with a dollar sign are shell variables. */
      char *savecp;
      EXPR_CONTEXT ec;
      int peektok;

      while (legal_variable_char (c))
	c = *cp++;

      c = *--cp;

#if defined (ARRAY_VARS)
      if (c == '[')
	{
	  e = skipsubscript (cp, 0, 0);
	  if (cp[e] == ']')
	    {
	      cp += e + 1;
	      c = *cp;
	      e = ']';
	    }
	  else
	    evalerror (bash_badsub_errmsg);
	}
#endif /* ARRAY_VARS */

      *cp = '\0';
      FREE (tokstr);
      tokstr = savestring (tp);
      *cp = c;

      /* XXX - make peektok part of saved token state? */
      SAVETOK (&ec);
      tokstr = (char *)NULL;	/* keep it from being freed */
      tp = savecp = cp;
      noeval = 1;
      curtok = STR;
      readtok ();
      peektok = curtok;
      if (peektok == STR)	/* free new tokstr before old one is restored */
	FREE (tokstr);
      RESTORETOK (&ec);
      cp = savecp;

      /* The tests for PREINC and PREDEC aren't strictly correct, but they
	 preserve old behavior if a construct like --x=9 is given. */
      if (lasttok == PREINC || lasttok == PREDEC || peektok != EQ)
        {
          lastlval = curlval;
	  tokval = expr_streval (tokstr, e, &curlval);
        }
      else
	tokval = 0;

      lasttok = curtok;
      curtok = STR;
    }
  else if (DIGIT(c))
    {
      while (ISALNUM (c) || c == '#' || c == '@' || c == '_')
	c = *cp++;

      c = *--cp;
      *cp = '\0';

      tokval = strlong (tp);
      *cp = c;
      lasttok = curtok;
      curtok = NUM;
    }
  else
    {
      c1 = *cp++;
      if ((c == EQ) && (c1 == EQ))
	c = EQEQ;
      else if ((c == NOT) && (c1 == EQ))
	c = NEQ;
      else if ((c == GT) && (c1 == EQ))
	c = GEQ;
      else if ((c == LT) && (c1 == EQ))
	c = LEQ;
      else if ((c == LT) && (c1 == LT))
	{
	  if (*cp == '=')	/* a <<= b */
	    {
	      assigntok = LSH;
	      c = OP_ASSIGN;
	      cp++;
	    }
	  else
	    c = LSH;
	}
      else if ((c == GT) && (c1 == GT))
	{
	  if (*cp == '=')
	    {
	      assigntok = RSH;	/* a >>= b */
	      c = OP_ASSIGN;
	      cp++;
	    }
	  else
	    c = RSH;
	}
      else if ((c == BAND) && (c1 == BAND))
	c = LAND;
      else if ((c == BOR) && (c1 == BOR))
	c = LOR;
      else if ((c == '*') && (c1 == '*'))
	c = POWER;
      else if ((c == '-' || c == '+') && c1 == c && curtok == STR)
	c = (c == '-') ? POSTDEC : POSTINC;
      else if ((c == '-' || c == '+') && c1 == c)
	{
	  /* Quickly scan forward to see if this is followed by optional
	     whitespace and an identifier. */
	  xp = cp;
	  while (xp && *xp && cr_whitespace (*xp))
	    xp++;
	  if (legal_variable_starter ((unsigned char)*xp))
	    c = (c == '-') ? PREDEC : PREINC;
	  else
	    cp--;	/* not preinc or predec, so unget the character */
	}
      else if (c1 == EQ && member (c, "*/%+-&^|"))
	{
	  assigntok = c;	/* a OP= b */
	  c = OP_ASSIGN;
	}
      else if (_is_arithop (c) == 0)
	{
	  cp--;
	  /* use curtok, since it hasn't been copied to lasttok yet */
	  if (curtok == 0 || _is_arithop (curtok) || _is_multiop (curtok))
	    evalerror (_("syntax error: operand expected"));
	  else
	    evalerror (_("syntax error: invalid arithmetic operator"));
	}
      else
	cp--;			/* `unget' the character */

      /* Should check here to make sure that the current character is one
	 of the recognized operators and flag an error if not.  Could create
	 a character map the first time through and check it on subsequent
	 calls. */
      lasttok = curtok;
      curtok = c;
    }
  tp = cp;
}

static void
evalerror (msg)
     const char *msg;
{
  char *name, *t;

  name = this_command_name;
  for (t = expression; whitespace (*t); t++)
    ;
  internal_error (_("%s%s%s: %s (error token is \"%s\")"),
		   name ? name : "", name ? ": " : "", t,
		   msg, (lasttp && *lasttp) ? lasttp : "");
  longjmp (evalbuf, 1);
}

/* Convert a string to an intmax_t integer, with an arbitrary base.
   0nnn -> base 8
   0[Xx]nn -> base 16
   Anything else: [base#]number (this is implemented to match ksh93)

   Base may be >=2 and <=64.  If base is <= 36, the numbers are drawn
   from [0-9][a-zA-Z], and lowercase and uppercase letters may be used
   interchangably.  If base is > 36 and <= 64, the numbers are drawn
   from [0-9][a-z][A-Z]_@ (a = 10, z = 35, A = 36, Z = 61, @ = 62, _ = 63 --
   you get the picture). */

static intmax_t
strlong (num)
     char *num;
{
  register char *s;
  register unsigned char c;
  int base, foundbase;
  intmax_t val;

  s = num;

  base = 10;
  foundbase = 0;
  if (*s == '0')
    {
      s++;

      if (*s == '\0')
	return 0;

       /* Base 16? */
      if (*s == 'x' || *s == 'X')
	{
	  base = 16;
	  s++;
	}
      else
	base = 8;
      foundbase++;
    }

  val = 0;
  for (c = *s++; c; c = *s++)
    {
      if (c == '#')
	{
	  if (foundbase)
	    evalerror (_("invalid number"));

	  /* Illegal base specifications raise an evaluation error. */
	  if (val < 2 || val > 64)
	    evalerror (_("invalid arithmetic base"));

	  base = val;
	  val = 0;
	  foundbase++;
	}
      else if (ISALNUM(c) || (c == '_') || (c == '@'))
	{
	  if (DIGIT(c))
	    c = TODIGIT(c);
	  else if (c >= 'a' && c <= 'z')
	    c -= 'a' - 10;
	  else if (c >= 'A' && c <= 'Z')
	    c -= 'A' - ((base <= 36) ? 10 : 36);
	  else if (c == '@')
	    c = 62;
	  else if (c == '_')
	    c = 63;

	  if (c >= base)
	    evalerror (_("value too great for base"));

	  val = (val * base) + c;
	}
      else
	break;
    }

  return (val);
}

#if defined (EXPR_TEST)
void *
xmalloc (n)
     int n;
{
  return (malloc (n));
}

void *
xrealloc (s, n)
     char *s;
     int n;
{
  return (realloc (s, n));
}

SHELL_VAR *find_variable () { return 0;}
SHELL_VAR *bind_variable () { return 0; }

char *get_string_value () { return 0; }

procenv_t top_level;

main (argc, argv)
     int argc;
     char **argv;
{
  register int i;
  intmax_t v;
  int expok;

  if (setjmp (top_level))
    exit (0);

  for (i = 1; i < argc; i++)
    {
      v = evalexp (argv[i], &expok);
      if (expok == 0)
	fprintf (stderr, _("%s: expression error\n"), argv[i]);
      else
	printf ("'%s' -> %ld\n", argv[i], v);
    }
  exit (0);
}

int
builtin_error (format, arg1, arg2, arg3, arg4, arg5)
     char *format;
{
  fprintf (stderr, "expr: ");
  fprintf (stderr, format, arg1, arg2, arg3, arg4, arg5);
  fprintf (stderr, "\n");
  return 0;
}

char *
itos (n)
     intmax_t n;
{
  return ("42");
}

#endif /* EXPR_TEST */