cpplib.c

gcc库的原代码,对编程有很大帮助.

	case '\"':
	  goto scan_directive_token;
	  break;
	case '/':
	  nextc = PEEKC();
	  if (nextc == '*' || (opts->cplusplus_comments && nextc == '*'))
	    goto scan_directive_token;
	  break;
	case '\f':
	case '\v':
	  if (CPP_PEDANTIC (pfile))
	    cpp_pedwarn (pfile, "%s in preprocessing directive",
			 c == '\f' ? "formfeed" : "vertical tab");
	  break;

	case '\n':
	  FORWARD(-1);
	  goto end_directive;
	scan_directive_token:
	  FORWARD(-1);
	  cpp_get_token (pfile);
	  continue;
	}
      CPP_PUTC (pfile, c);
    }
 end_directive: ;
  CPP_NUL_TERMINATE (pfile);
}

void
skip_rest_of_line (pfile)
     cpp_reader *pfile;
{
  long old = CPP_WRITTEN (pfile);
  copy_rest_of_line (pfile);
  CPP_SET_WRITTEN (pfile, old);
}

/* Handle a possible # directive.
   '#' has already been read.  */

int
handle_directive (pfile)
     cpp_reader *pfile;
{ int c;
  register struct directive *kt;
  int ident_length;
  long after_ident;
  U_CHAR *ident, *line_end;
  long old_written = CPP_WRITTEN (pfile);

  cpp_skip_hspace (pfile);

  c = PEEKC ();
  if (c >= '0' && c <= '9')
    {
      /* Handle # followed by a line number.  */
      if (CPP_PEDANTIC (pfile))
	cpp_pedwarn (pfile, "`#' followed by integer");
      do_line (pfile, NULL);
      goto done_a_directive;
    }

  /* Now find the directive name. */
  CPP_PUTC (pfile, '#');
  parse_name (pfile, GETC());
  ident = pfile->token_buffer + old_written + 1;
  ident_length = CPP_PWRITTEN (pfile) - ident;
  if (ident_length == 0 && PEEKC() == '\n')
    {
      /* A line of just `#' becomes blank.  */
      goto done_a_directive;
    }

#if 0
  if (ident_length == 0 || !is_idstart[*ident]) {
    U_CHAR *p = ident;
    while (is_idchar[*p]) {
      if (*p < '0' || *p > '9')
	break;
      p++;
    }
    /* Avoid error for `###' and similar cases unless -pedantic.  */
    if (p == ident) {
      while (*p == '#' || is_hor_space[*p]) p++;
      if (*p == '\n') {
	if (pedantic && !lang_asm)
	  cpp_warning (pfile, "invalid preprocessor directive");
	return 0;
      }
    }

    if (!lang_asm)
      cpp_error (pfile, "invalid preprocessor directive name");

    return 0;
  }
#endif
  /*
   * Decode the keyword and call the appropriate expansion
   * routine, after moving the input pointer up to the next line.
   */
  for (kt = directive_table; ; kt++) {
    if (kt->length <= 0)
      goto not_a_directive;
    if (kt->length == ident_length && !strncmp (kt->name, ident, ident_length)) 
      break;
  }

  if (! kt->command_reads_line)
    {
      /* Nonzero means do not delete comments within the directive.
         #define needs this when -traditional.  */
	int comments = CPP_TRADITIONAL (pfile) && kt->traditional_comments; 
	int save_put_out_comments = CPP_OPTIONS (pfile)->put_out_comments;
	CPP_OPTIONS (pfile)->put_out_comments = comments;
	after_ident = CPP_WRITTEN (pfile);
	copy_rest_of_line (pfile);
	CPP_OPTIONS (pfile)->put_out_comments = save_put_out_comments;
    }

  /* For #pragma and #define, we may want to pass through the directive.
     Other directives may create output, but we don't want the directive
     itself out, so we pop it now.  For example #include may write a #line
     command (see comment in do_include), and conditionals may emit
     #failed ... #endfailed stuff.  But note that popping the buffer
     means the parameters to kt->func may point after pfile->limit
     so these parameters are invalid as soon as something gets appended
     to the token_buffer.  */

  line_end = CPP_PWRITTEN (pfile);
  if (!kt->pass_thru && kt->type != T_DEFINE)
    CPP_SET_WRITTEN (pfile, old_written);

  (*kt->func) (pfile, kt, pfile->token_buffer + after_ident, line_end);
  if (kt->pass_thru
      || (kt->type == T_DEFINE
	  && CPP_OPTIONS (pfile)->dump_macros == dump_definitions))
    {
      /* Just leave the entire #define in the output stack. */
    }
  else if (kt->type == T_DEFINE
	   && CPP_OPTIONS (pfile)->dump_macros == dump_names)
    {
      U_CHAR *p = pfile->token_buffer + old_written + 7;  /* Skip "#define". */
      SKIP_WHITE_SPACE (p);
      while (is_idchar[*p]) p++;
      pfile->limit = p;
      CPP_PUTC (pfile, '\n');
    }
  else if (kt->type == T_DEFINE)
    CPP_SET_WRITTEN (pfile, old_written);
 done_a_directive:
  return 1;

 not_a_directive:
  return 0;
}

/* Pass a directive through to the output file.
   BUF points to the contents of the directive, as a contiguous string.
   LIMIT points to the first character past the end of the directive.
   KEYWORD is the keyword-table entry for the directive.  */

static void
pass_thru_directive (buf, limit, pfile, keyword)
     U_CHAR *buf, *limit;
     cpp_reader *pfile;
     struct directive *keyword;
{
  register unsigned keyword_length = keyword->length;

  CPP_RESERVE (pfile, 1 + keyword_length + (limit - buf));
  CPP_PUTC_Q (pfile, '#');
  CPP_PUTS_Q (pfile, keyword->name, keyword_length);
  if (limit != buf && buf[0] != ' ')
    CPP_PUTC_Q (pfile, ' ');
  CPP_PUTS_Q (pfile, buf, limit - buf);
#if 0
  CPP_PUTS_Q (pfile, '\n');
  /* Count the line we have just made in the output,
     to get in sync properly.  */
  pfile->lineno++;
#endif
}

/* The arglist structure is built by do_define to tell
   collect_definition where the argument names begin.  That
   is, for a define like "#define f(x,y,z) foo+x-bar*y", the arglist
   would contain pointers to the strings x, y, and z.
   Collect_definition would then build a DEFINITION node,
   with reflist nodes pointing to the places x, y, and z had
   appeared.  So the arglist is just convenience data passed
   between these two routines.  It is not kept around after
   the current #define has been processed and entered into the
   hash table. */

struct arglist {
  struct arglist *next;
  U_CHAR *name;
  int length;
  int argno;
  char rest_args;
};

/* Read a replacement list for a macro with parameters.
   Build the DEFINITION structure.
   Reads characters of text starting at BUF until END.
   ARGLIST specifies the formal parameters to look for
   in the text of the definition; NARGS is the number of args
   in that list, or -1 for a macro name that wants no argument list.
   MACRONAME is the macro name itself (so we can avoid recursive expansion)
   and NAMELEN is its length in characters.
   
   Note that comments, backslash-newlines, and leading white space
   have already been deleted from the argument.  */

static DEFINITION *
collect_expansion (pfile, buf, limit, nargs, arglist)
     cpp_reader *pfile;
     U_CHAR *buf, *limit;
     int nargs;
     struct arglist *arglist;
{
  DEFINITION *defn;
  register U_CHAR *p, *lastp, *exp_p;
  struct reflist *endpat = NULL;
  /* Pointer to first nonspace after last ## seen.  */
  U_CHAR *concat = 0;
  /* Pointer to first nonspace after last single-# seen.  */
  U_CHAR *stringify = 0;
  int maxsize;
  int expected_delimiter = '\0';

  /* Scan thru the replacement list, ignoring comments and quoted
     strings, picking up on the macro calls.  It does a linear search
     thru the arg list on every potential symbol.  Profiling might say
     that something smarter should happen. */

  if (limit < buf)
    abort ();

  /* Find the beginning of the trailing whitespace.  */
  p = buf;
  while (p < limit && is_space[limit[-1]]) limit--;

  /* Allocate space for the text in the macro definition.
     Leading and trailing whitespace chars need 2 bytes each.
     Each other input char may or may not need 1 byte,
     so this is an upper bound.  The extra 5 are for invented
     leading and trailing newline-marker and final null.  */
  maxsize = (sizeof (DEFINITION)
	     + (limit - p) + 5);
  /* Occurrences of '@' get doubled, so allocate extra space for them. */
  while (p < limit)
    if (*p++ == '@')
      maxsize++;
  defn = (DEFINITION *) xcalloc (1, maxsize);

  defn->nargs = nargs;
  exp_p = defn->expansion = (U_CHAR *) defn + sizeof (DEFINITION);
  lastp = exp_p;

  p = buf;

  /* Add one initial space escape-marker to prevent accidental
     token-pasting (often removed by macroexpand). */
  *exp_p++ = '@';
  *exp_p++ = ' ';

  if (limit - p >= 2 && p[0] == '#' && p[1] == '#') {
    cpp_error (pfile, "`##' at start of macro definition");
    p += 2;
  }

  /* Process the main body of the definition.  */
  while (p < limit) {
    int skipped_arg = 0;
    register U_CHAR c = *p++;

    *exp_p++ = c;

    if (!CPP_TRADITIONAL (pfile)) {
      switch (c) {
      case '\'':
      case '\"':
        if (expected_delimiter != '\0') {
          if (c == expected_delimiter)
            expected_delimiter = '\0';
        } else
          expected_delimiter = c;
	break;

      case '\\':
	if (p < limit && expected_delimiter) {
	  /* In a string, backslash goes through
	     and makes next char ordinary.  */
	  *exp_p++ = *p++;
	}
	break;

      case '@':
	/* An '@' in a string or character constant stands for itself,
	   and does not need to be escaped. */
	if (!expected_delimiter)
	  *exp_p++ = c;
	break;

      case '#':
	/* # is ordinary inside a string.  */
	if (expected_delimiter)
	  break;
	if (p < limit && *p == '#') {
	  /* ##: concatenate preceding and following tokens.  */
	  /* Take out the first #, discard preceding whitespace.  */
	  exp_p--;
	  while (exp_p > lastp && is_hor_space[exp_p[-1]])
	    --exp_p;
	  /* Skip the second #.  */
	  p++;
	  /* Discard following whitespace.  */
	  SKIP_WHITE_SPACE (p);
	  concat = p;
	  if (p == limit)
	    cpp_error (pfile, "`##' at end of macro definition");
	} else if (nargs >= 0) {
	  /* Single #: stringify following argument ref.
	     Don't leave the # in the expansion.  */
	  exp_p--;
	  SKIP_WHITE_SPACE (p);
	  if (p == limit || ! is_idstart[*p])
	    cpp_error (pfile,
		     "`#' operator is not followed by a macro argument name");
	  else
	    stringify = p;
	}
	break;
      }
    } else {
      /* In -traditional mode, recognize arguments inside strings and
	 and character constants, and ignore special properties of #.
	 Arguments inside strings are considered "stringified", but no
	 extra quote marks are supplied.  */
      switch (c) {
      case '\'':
      case '\"':
	if (expected_delimiter != '\0') {
	  if (c == expected_delimiter)
	    expected_delimiter = '\0';
	} else
	  expected_delimiter = c;
	break;

      case '\\':
	/* Backslash quotes delimiters and itself, but not macro args.  */
	if (expected_delimiter != 0 && p < limit
	    && (*p == expected_delimiter || *p == '\\')) {
	  *exp_p++ = *p++;
	  continue;
	}
	break;

      case '/':
	if (expected_delimiter != '\0') /* No comments inside strings.  */
	  break;
	if (*p == '*') {
	  /* If we find a comment that wasn't removed by handle_directive,
	     this must be -traditional.  So replace the comment with
	     nothing at all.  */
	  exp_p--;
	  p += 1;
	  while (p < limit && !(p[-2] == '*' && p[-1] == '/'))
	    p++;
#if 0
	  /* Mark this as a concatenation-point, as if it had been ##.  */
	  concat = p;
#endif
	}
	break;
      }
    }

    /* Handle the start of a symbol.  */
    if (is_idchar[c] && nargs > 0) {
      U_CHAR *id_beg = p - 1;
      int id_len;

      --exp_p;
      while (p != limit && is_idchar[*p]) p++;
      id_len = p - id_beg;

      if (is_idstart[c]) {
	register struct arglist *arg;

	for (arg = arglist; arg != NULL; arg = arg->next) {
	  struct reflist *tpat;

	  if (arg->name[0] == c
	      && arg->length == id_len
	      && strncmp (arg->name, id_beg, id_len) == 0) {
	    if (expected_delimiter && CPP_OPTIONS (pfile)->warn_stringify) {
	      if (CPP_TRADITIONAL (pfile)) {
		cpp_warning (pfile, "macro argument `%.*s' is stringified.",
			     id_len, arg->name);
	      } else {
		cpp_warning (pfile,
		    "macro arg `%.*s' would be stringified with -traditional.",
			     id_len, arg->name);
	      }
	    }
	    /* If ANSI, don't actually substitute inside a string.  */
	    if (!CPP_TRADITIONAL (pfile) && expected_delimiter)
	      break;
	    /* make a pat node for this arg and append it to the end of
	       the pat list */
	    tpat = (struct reflist *) xmalloc (sizeof (struct reflist));
	    tpat->next = NULL;
	    tpat->raw_before = concat == id_beg;
	    tpat->raw_after = 0;
	    tpat->rest_args = arg->rest_args;
	    tpat->stringify = (CPP_TRADITIONAL (pfile)
			       ? expected_delimiter != '\0'
			       : stringify == id_beg);

	    if (endpat == NULL)
	      defn->pattern = tpat;
	    else
	      endpat->next = tpat;
	    endpat = tpat;

	    tpat->argno = arg->argno;
	    tpat->nchars = exp_p - lastp;
	    {
	      register U_CHAR *p1 = p;
	      SKIP_WHITE_SPACE (p1);
	      if (p1 + 2 <= limit && p1[0] == '#' && p1[1] == '#')
		tpat->raw_after = 1;
	    }
	    lastp = exp_p;	/* place to start copying from next time */
	    skipped_arg = 1;
	    break;
	  }
	}
      }

      /* If this was not a macro arg, copy it into the expansion.  */
      if (! skipped_arg) {
	register U_CHAR *lim1 = p;
	p = id_beg;
	while (p != lim1)
	  *exp_p++ = *p++;
	if (stringify == id_beg)
	  cpp_error (pfile,
		   "`#' operator should be followed by a macro argument name");
      }
    }
  }

  if (!CPP_TRADITIONAL (pfile) && expected_delimiter == 0)
    {
      /* If ANSI, put in a "@ " marker to prevent token pasting.
         But not if "inside a string" (which in ANSI mode
         happens only for -D option).  */
      *exp_p++ = '@';
      *exp_p++ = ' ';
    }

  *exp_p = '\0';

  defn->length = exp_p - defn->expansion;

  /* Crash now if we overrun the allocated size.  */
  if (defn->length + 1 > maxsize)
    abort ();

#if 0
/* This isn't worth the time it takes.  */
  /* give back excess storage */
  defn->expansion = (U_CHAR *) xrealloc (defn->expansion, defn->length + 1);
#endif

  return defn;
}

/*
 * special extension string that can be added to the last macro argument to 
 * allow it to absorb the "rest" of the arguments when expanded.  Ex:
 * 		#define wow(a, b...)		process (b, a, b)
 *		{ wow (1, 2, 3); }	->	{ process (2, 3, 1, 2, 3); }
 *		{ wow (one, two); }	->	{ process (two, one, two); }
 * if this "rest_arg" is used with the concat token '##' and if it is not
 * supplied then the token attached to with ## will not be outputted.  Ex:
 * 		#define wow (a, b...)		process (b ## , a, ## b)
 *		{ wow (1, 2); }		->	{ process (2, 1, 2); }
 *		{ wow (one); }		->	{ process (one); {
 */
static char rest_extension[] = "...";
#define REST_EXTENSION_LENGTH	(sizeof (rest_extension) - 1)

/* Create a DEFINITION node from a #define directive.  Arguments are 
   as for do_define. */
static MACRODEF
create_definition (buf, limit, pfile, predefinition)