c-parse.y

这是完整的gcc源代码

      if (token == CONSTANT
	  && TREE_CODE (yylval.ttype) == INTEGER_CST)
	{
	  if (TREE_INT_CST_LOW (yylval.ttype) == 1)
	    {
	      struct file_stack *p
		= (struct file_stack *) xmalloc (sizeof (struct file_stack));
	      input_file_stack->line = old_lineno;
	      p->next = input_file_stack;
	      p->name = input_filename;
	      input_file_stack = p;
	      input_file_stack_tick++;
	    }
	  else if (input_file_stack->next)
	    {
	      struct file_stack *p = input_file_stack;
	      input_file_stack = p->next;
	      free (p);
	      input_file_stack_tick++;
	    }
	  else
	    error ("#-lines for entering and leaving files don't match");
	}
    }
  else
    error ("invalid #-line");

  /* skip the rest of this line.  */
 skipline:
  if (c == '\n')
    return c;
  while ((c = getc (finput)) != EOF && c != '\n');
  return c;
}

#define isalnum(char) ((char >= 'a' && char <= 'z') || (char >= 'A' && char <= 'Z') || (char >= '0' && char <= '9'))
#define isdigit(char) (char >= '0' && char <= '9')
#define ENDFILE -1  /* token that represents end-of-file */


static int
readescape ()
{
  register int c = getc (finput);
  register int count, code;
  int firstdig;

  switch (c)
    {
    case 'x':
      code = 0;
      count = 0;
      while (1)
	{
	  c = getc (finput);
	  if (!(c >= 'a' && c <= 'f')
	      && !(c >= 'A' && c <= 'F')
	      && !(c >= '0' && c <= '9'))
	    {
	      ungetc (c, finput);
	      break;
	    }
	  code *= 16;
	  if (c >= 'a' && c <= 'f')
	    code += c - 'a' + 10;
	  if (c >= 'A' && c <= 'F')
	    code += c - 'A' + 10;
	  if (c >= '0' && c <= '9')
	    code += c - '0';
	  if (count == 0)
	    firstdig = code;
	  count++;
	}
      if (count == 0)
	error ("\\x used with no following hex digits");
      else if ((count - 1) * 4 >= TYPE_PRECISION (integer_type_node)
	       || (count > 1
		   && ((1 << (TYPE_PRECISION (integer_type_node) - (count - 1) * 4))
		       <= firstdig)))
	warning ("hex escape out of range");
      return code;

    case '0':  case '1':  case '2':  case '3':  case '4':
    case '5':  case '6':  case '7':
      code = 0;
      count = 0;
      while ((c <= '7') && (c >= '0') && (count++ < 3))
	{
	  code = (code * 8) + (c - '0');
	  c = getc (finput);
	}
      ungetc (c, finput);
      return code;

    case '\\': case '\'': case '"':
      return c;

    case '\n':
      lineno++;
      return -1;

    case 'n':
      return TARGET_NEWLINE;

    case 't':
      return TARGET_TAB;

    case 'r':
      return TARGET_CR;

    case 'f':
      return TARGET_FF;

    case 'b':
      return TARGET_BS;

    case 'a':
      return TARGET_BELL;

    case 'v':
      return TARGET_VT;

    case 'E':
      return 033;

    case '?':
      /* `\(', etc, are used at beginning of line to avoid confusing Emacs.  */
    case '(':
    case '{':
    case '[':
      return c;
    }
  if (c >= 040 && c <= 0177)
    warning ("unknown escape sequence `\\%c'", c);
  else
    warning ("unknown escape sequence: `\\' followed by char code 0x%x", c);
  return c;
}

void
yyerror (string)
     char *string;
{
  char buf[200];

  strcpy (buf, string);

  /* We can't print string and character constants well
     because the token_buffer contains the result of processing escapes.  */
  if (end_of_file)
    strcat (buf, " at end of input");
  else if (token_buffer[0] == 0)
    strcat (buf, " at null character");
  else if (token_buffer[0] == '"')
    strcat (buf, " before string constant");
  else if (token_buffer[0] == '\'')
    strcat (buf, " before character constant");
  else if (token_buffer[0] < 040 || token_buffer[0] >= 0177)
    sprintf (buf + strlen (buf), " before character 0%o", token_buffer[0]);
  else
    strcat (buf, " before `%s'");

  error (buf, token_buffer);
}

static 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 '\r':
      case '\v':
      case '\b':
	c = getc (finput);
	break;

      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);
      }

    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 == '$')
	{
	  if (p >= token_buffer + maxtoken)
	    p = extend_token_buffer (p);
	  if (c == '$' && ! 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];
	    if ((! flag_no_asm
		 /* -fno-asm means don't recognize the non-ANSI keywords.  */
		 || ((int) ptr->token != ASM
		     && (int) ptr->token != TYPEOF
		     && ptr->rid != RID_INLINE)
		 /* Recognize __asm and __inline despite -fno-asm.  */
		 || token_buffer[0] == '_')
		/* -ftraditional means don't recognize nontraditional keywords
		   typeof, const, volatile, signed or inline.  */
		&& (! flag_traditional
		    || ((int) ptr->token != TYPE_QUAL
			&& (int) ptr->token != TYPEOF
			&& ptr->rid != RID_SIGNED
			&& ptr->rid != RID_INLINE)
		    /* Recognize __inline, etc. despite -ftraditional.  */
		    || token_buffer[0] == '_'))
	      {
		value = (int) ptr->token;
		/* Even if we decided to recognize asm, still perhaps warn.  */
		if (pedantic
		    && (value == ASM || value == TYPEOF
			|| ptr->rid == RID_INLINE)
		    && token_buffer[0] != '_')
		  warning ("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;
	}

      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 store only 8 live bits in each short,
	   giving us 64 bits of reliable precision */
	short shorts[8];
	int overflow = 0;

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

	for (count = 0; count < 8; count++)
	  shorts[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));
	      }
	    else
	      {
		base = 8;
		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 < 8; count++)
		  {
		    shorts[count] *= base;
		    if (count)
		      {
			shorts[count] += (shorts[count-1] >> 8);
			shorts[count-1] &= (1<<8)-1;
		      }
		    else shorts[0] += c;
		  }

		if (shorts[7] >= 1<<8
		    || shorts[7] < - (1 << 8))
		  overflow = TRUE;

		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;
	    char f_seen = 0;
	    char l_seen = 0;
	    REAL_VALUE_TYPE value;

	    /* 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