c-lex.c

早期freebsd实现

  char long_flag;
  char long_long_flag;
};

struct try_type type_sequence[] = 
{
  { &integer_type_node, 0, 0, 0},
  { &unsigned_type_node, 1, 0, 0},
  { &long_integer_type_node, 0, 1, 0},
  { &long_unsigned_type_node, 1, 1, 0},
  { &long_long_integer_type_node, 0, 1, 1},
  { &long_long_unsigned_type_node, 1, 1, 1}
};
#endif /* 0 */

int
yylex ()
{
  register int c;
  register char *p;
  register int value;
  int wide_flag = 0;

  if (nextchar >= 0)
    c = nextchar, nextchar = -1;
  else
    c = getc (finput);

  /* Effectively do c = skip_white_space (c)
     but do it faster in the usual cases.  */
  while (1)
    switch (c)
      {
      case ' ':
      case '\t':
      case '\f':
      case '\v':
      case '\b':
	c = getc (finput);
	break;

      case '\r':
	/* Call skip_white_space so we can warn if appropriate.  */

      case '\n':
      case '/':
      case '\\':
	c = skip_white_space (c);
      default:
	goto found_nonwhite;
      }
 found_nonwhite:

  token_buffer[0] = c;
  token_buffer[1] = 0;

/*  yylloc.first_line = lineno; */

  switch (c)
    {
    case EOF:
      end_of_file = 1;
      token_buffer[0] = 0;
      value = ENDFILE;
      break;

    case '$':
      if (dollars_in_ident)
	goto letter;
      return '$';

    case 'L':
      /* Capital L may start a wide-string or wide-character constant.  */
      {
	register int c = getc (finput);
	if (c == '\'')
	  {
	    wide_flag = 1;
	    goto char_constant;
	  }
	if (c == '"')
	  {
	    wide_flag = 1;
	    goto string_constant;
	  }
	ungetc (c, finput);
      }
      goto letter;

    case '@':
      if (!doing_objc_thang)
	{
	  value = c;
	  break;
	}
      p = token_buffer;
      *p++ = '@';
      c = getc (finput);
      while (isalnum (c) || c == '_')
	{
	  if (p >= token_buffer + maxtoken)
	    p = extend_token_buffer (p);

	  *p++ = c;
	  c = getc (finput);
	}

      *p = 0;
      nextchar = c;
      value = recognize_objc_keyword (token_buffer + 1);
      if (value != 0)
	break;
      error ("invalid Objective C keyword `%s'", token_buffer);
      /* Cause a syntax error--1 is not a valid token type.  */
      value = 1;
      break;

    case 'A':  case 'B':  case 'C':  case 'D':  case 'E':
    case 'F':  case 'G':  case 'H':  case 'I':  case 'J':
    case 'K':		  case 'M':  case 'N':  case 'O':
    case 'P':  case 'Q':  case 'R':  case 'S':  case 'T':
    case 'U':  case 'V':  case 'W':  case 'X':  case 'Y':
    case 'Z':
    case 'a':  case 'b':  case 'c':  case 'd':  case 'e':
    case 'f':  case 'g':  case 'h':  case 'i':  case 'j':
    case 'k':  case 'l':  case 'm':  case 'n':  case 'o':
    case 'p':  case 'q':  case 'r':  case 's':  case 't':
    case 'u':  case 'v':  case 'w':  case 'x':  case 'y':
    case 'z':
    case '_':
    letter:
      p = token_buffer;
      while (isalnum (c) || c == '_' || c == '$' || c == '@')
	{
	  if (p >= token_buffer + maxtoken)
	    p = extend_token_buffer (p);
	  if (c == '$' && ! dollars_in_ident)
	    break;

	  *p++ = c;
	  c = getc (finput);
	}

      *p = 0;
      nextchar = c;

      value = IDENTIFIER;
      yylval.itype = 0;

      /* Try to recognize a keyword.  Uses minimum-perfect hash function */

      {
	register struct resword *ptr;

	if (ptr = is_reserved_word (token_buffer, p - token_buffer))
	  {
	    if (ptr->rid)
	      yylval.ttype = ridpointers[(int) ptr->rid];
	    value = (int) ptr->token;

	    /* Even if we decided to recognize asm, still perhaps warn.  */
	    if (pedantic
		&& (value == ASM_KEYWORD || value == TYPEOF
		    || ptr->rid == RID_INLINE)
		&& token_buffer[0] != '_')
	      pedwarn ("ANSI does not permit the keyword `%s'",
		       token_buffer);
	  }
      }

      /* If we did not find a keyword, look for an identifier
	 (or a typename).  */

      if (value == IDENTIFIER)
	{
          yylval.ttype = get_identifier (token_buffer);
	  lastiddecl = lookup_name (yylval.ttype);

	  if (lastiddecl != 0 && TREE_CODE (lastiddecl) == TYPE_DECL)
	    value = TYPENAME;
	  /* A user-invisible read-only initialized variable
	     should be replaced by its value.
	     We handle only strings since that's the only case used in C.  */
	  else if (lastiddecl != 0 && TREE_CODE (lastiddecl) == VAR_DECL
		   && DECL_IGNORED_P (lastiddecl)
		   && TREE_READONLY (lastiddecl)
		   && DECL_INITIAL (lastiddecl) != 0
		   && TREE_CODE (DECL_INITIAL (lastiddecl)) == STRING_CST)
	    {
	      yylval.ttype = DECL_INITIAL (lastiddecl);
	      value = STRING;
	    }
          else if (doing_objc_thang)
            {
	      tree objc_interface_decl = lookup_interface (yylval.ttype);

	      if (objc_interface_decl)
		{
		  value = CLASSNAME;
		  yylval.ttype = objc_interface_decl;
		}
	    }
	}

      break;

    case '0':  case '1':  case '2':  case '3':  case '4':
    case '5':  case '6':  case '7':  case '8':  case '9':
    case '.':
      {
	int base = 10;
	int count = 0;
	int largest_digit = 0;
	int numdigits = 0;
	/* for multi-precision arithmetic,
	   we actually store only HOST_BITS_PER_CHAR bits in each part.
	   The number of parts is chosen so as to be sufficient to hold
	   the enough bits to fit into the two HOST_WIDE_INTs that contain
	   the integer value (this is always at least as many bits as are
	   in a target `long long' value, but may be wider).  */
#define TOTAL_PARTS ((HOST_BITS_PER_WIDE_INT / HOST_BITS_PER_CHAR) * 2 + 2)
	int parts[TOTAL_PARTS];
	int overflow = 0;

	enum anon1 { NOT_FLOAT, AFTER_POINT, TOO_MANY_POINTS} floatflag
	  = NOT_FLOAT;

	for (count = 0; count < TOTAL_PARTS; count++)
	  parts[count] = 0;

	p = token_buffer;
	*p++ = c;

	if (c == '0')
	  {
	    *p++ = (c = getc (finput));
	    if ((c == 'x') || (c == 'X'))
	      {
		base = 16;
		*p++ = (c = getc (finput));
	      }
	    /* Leading 0 forces octal unless the 0 is the only digit.  */
	    else if (c >= '0' && c <= '9')
	      {
		base = 8;
		numdigits++;
	      }
	    else
	      numdigits++;
	  }

	/* Read all the digits-and-decimal-points.  */

	while (c == '.'
	       || (isalnum (c) && (c != 'l') && (c != 'L')
		   && (c != 'u') && (c != 'U')
		   && (floatflag == NOT_FLOAT || ((c != 'f') && (c != 'F')))))
	  {
	    if (c == '.')
	      {
		if (base == 16)
		  error ("floating constant may not be in radix 16");
		if (floatflag == AFTER_POINT)
		  {
		    error ("malformed floating constant");
		    floatflag = TOO_MANY_POINTS;
		  }
		else
		  floatflag = AFTER_POINT;

		base = 10;
		*p++ = c = getc (finput);
		/* Accept '.' as the start of a floating-point number
		   only when it is followed by a digit.
		   Otherwise, unread the following non-digit
		   and use the '.' as a structural token.  */
		if (p == token_buffer + 2 && !isdigit (c))
		  {
		    if (c == '.')
		      {
			c = getc (finput);
			if (c == '.')
			  {
			    *p++ = c;
			    *p = 0;
			    return ELLIPSIS;
			  }
			error ("parse error at `..'");
		      }
		    ungetc (c, finput);
		    token_buffer[1] = 0;
		    value = '.';
		    goto done;
		  }
	      }
	    else
	      {
		/* It is not a decimal point.
		   It should be a digit (perhaps a hex digit).  */

		if (isdigit (c))
		  {
		    c = c - '0';
		  }
		else if (base <= 10)
		  {
		    if ((c&~040) == 'E')
		      {
			base = 10;
			floatflag = AFTER_POINT;
			break;   /* start of exponent */
		      }
		    error ("nondigits in number and not hexadecimal");
		    c = 0;
		  }
		else if (c >= 'a')
		  {
		    c = c - 'a' + 10;
		  }
		else
		  {
		    c = c - 'A' + 10;
		  }
		if (c >= largest_digit)
		  largest_digit = c;
		numdigits++;

		for (count = 0; count < TOTAL_PARTS; count++)
		  {
		    parts[count] *= base;
		    if (count)
		      {
			parts[count]
			  += (parts[count-1] >> HOST_BITS_PER_CHAR);
			parts[count-1]
			  &= (1 << HOST_BITS_PER_CHAR) - 1;
		      }
		    else
		      parts[0] += c;
		  }

		/* If the extra highest-order part ever gets anything in it,
		   the number is certainly too big.  */
		if (parts[TOTAL_PARTS - 1] != 0)
		  overflow = 1;

		if (p >= token_buffer + maxtoken - 3)
		  p = extend_token_buffer (p);
		*p++ = (c = getc (finput));
	      }
	  }

	if (numdigits == 0)
	  error ("numeric constant with no digits");

	if (largest_digit >= base)
	  error ("numeric constant contains digits beyond the radix");

	/* Remove terminating char from the token buffer and delimit the string */
	*--p = 0;

	if (floatflag != NOT_FLOAT)
	  {
	    tree type = double_type_node;
	    int garbage_chars = 0, exceeds_double = 0;
	    REAL_VALUE_TYPE value;
	    jmp_buf handler;

	    /* Read explicit exponent if any, and put it in tokenbuf.  */

	    if ((c == 'e') || (c == 'E'))
	      {
		if (p >= token_buffer + maxtoken - 3)
		  p = extend_token_buffer (p);
		*p++ = c;
		c = getc (finput);
		if ((c == '+') || (c == '-'))
		  {
		    *p++ = c;
		    c = getc (finput);
		  }
		if (! isdigit (c))
		  error ("floating constant exponent has no digits");
	        while (isdigit (c))
		  {
		    if (p >= token_buffer + maxtoken - 3)
		      p = extend_token_buffer (p);
		    *p++ = c;
		    c = getc (finput);
		  }
	      }

	    *p = 0;
	    errno = 0;

	    /* Convert string to a double, checking for overflow.  */
	    if (setjmp (handler))
	      {
		error ("floating constant out of range");
		value = dconst0;
	      }
	    else
	      {
		set_float_handler (handler);
		value = REAL_VALUE_ATOF (token_buffer);
		set_float_handler (NULL_PTR);
	      }
#ifdef ERANGE
	    if (errno == ERANGE && !flag_traditional && pedantic)
	      {
  		/* ERANGE is also reported for underflow,
  		   so test the value to distinguish overflow from that.  */
		if (REAL_VALUES_LESS (dconst1, value)
		    || REAL_VALUES_LESS (value, dconstm1))
		  {
		    pedwarn ("floating point number exceeds range of `double'");
		    exceeds_double = 1;
		  }
	      }
#endif

	    /* Read the suffixes to choose a data type.  */
	    switch (c)
	      {
	      case 'f': case 'F':
		type = float_type_node;
		value = REAL_VALUE_TRUNCATE (TYPE_MODE (type), value);
		if (REAL_VALUE_ISINF (value) && ! exceeds_double && pedantic)
		  pedwarn ("floating point number exceeds range of `float'");
		garbage_chars = -1;
		break;

	      case 'l': case 'L':
		type = long_double_type_node;
		garbage_chars = -1;
		break;
	      }
	    /* Note: garbage_chars is -1 if first char is *not* garbage.  */
	    while (isalnum (c))
	      {
		if (p >= token_buffer + maxtoken - 3)
		  p = extend_token_buffer (p);
		*p++ = c;
		c = getc (finput);
		garbage_chars++;
	      }
	    if (garbage_chars > 0)
	      error ("garbage at end of number");

	    /* Create a node with determined type and value.  */
	    yylval.ttype = build_real (type, value);

	    ungetc (c, finput);
	    *p = 0;
	  }
	else
	  {
	    tree traditional_type, ansi_type, type;
	    HOST_WIDE_INT high, low;
	    int spec_unsigned = 0;
	    int spec_long = 0;
	    int spec_long_long = 0;
	    int bytes, warn, i;

	    while (1)
	      {
		if (c == 'u' || c == 'U')
		  {
		    if (spec_unsigned)
		      error ("two `u's in integer constant");
		    spec_unsigned = 1;
		  }
		else if (c == 'l' || c == 'L')
		  {
		    if (spec_long)
		      {
			if (spec_long_long)
			  error ("three `l's in integer constant");
			else if (pedantic)
			  pedwarn ("ANSI C forbids long long integer constants");
			spec_long_long = 1;
		      }