cpplib.c

gcc库的原代码,对编程有很大帮助.

     U_CHAR *buf, *limit;
     cpp_reader *pfile;
     int predefinition;
{
  U_CHAR *bp;			/* temp ptr into input buffer */
  U_CHAR *symname;		/* remember where symbol name starts */
  int sym_length;		/* and how long it is */
  int rest_args = 0;
  long line, col;
  char *file = CPP_BUFFER (pfile) ? CPP_BUFFER (pfile)->nominal_fname : "";
  DEFINITION *defn;
  int arglengths = 0;		/* Accumulate lengths of arg names
				   plus number of args.  */
  MACRODEF mdef;
  cpp_buf_line_and_col (CPP_BUFFER (pfile), &line, &col);

  bp = buf;

  while (is_hor_space[*bp])
    bp++;

  symname = bp;			/* remember where it starts */

  sym_length = check_macro_name (pfile, bp, "macro");
  bp += sym_length;

  /* Lossage will occur if identifiers or control keywords are broken
     across lines using backslash.  This is not the right place to take
     care of that. */

  if (*bp == '(') {
    struct arglist *arg_ptrs = NULL;
    int argno = 0;

    bp++;			/* skip '(' */
    SKIP_WHITE_SPACE (bp);

    /* Loop over macro argument names.  */
    while (*bp != ')') {
      struct arglist *temp;

      temp = (struct arglist *) alloca (sizeof (struct arglist));
      temp->name = bp;
      temp->next = arg_ptrs;
      temp->argno = argno++;
      temp->rest_args = 0;
      arg_ptrs = temp;

      if (rest_args)
	cpp_pedwarn (pfile, "another parameter follows `%s'", rest_extension);

      if (!is_idstart[*bp])
	cpp_pedwarn (pfile, "invalid character in macro parameter name");
      
      /* Find the end of the arg name.  */
      while (is_idchar[*bp]) {
	bp++;
	/* do we have a "special" rest-args extension here? */
	if (limit - bp > REST_EXTENSION_LENGTH &&
	    strncmp (rest_extension, bp, REST_EXTENSION_LENGTH) == 0) {
	  rest_args = 1;
	  temp->rest_args = 1;
	  break;
	}
      }
      temp->length = bp - temp->name;
      if (rest_args == 1)
	bp += REST_EXTENSION_LENGTH;
      arglengths += temp->length + 2;
      SKIP_WHITE_SPACE (bp);
      if (temp->length == 0 || (*bp != ',' && *bp != ')')) {
	cpp_error (pfile, "badly punctuated parameter list in `#define'");
	goto nope;
      }
      if (*bp == ',') {
	bp++;
	SKIP_WHITE_SPACE (bp);
      }
      if (bp >= limit) {
	cpp_error (pfile, "unterminated parameter list in `#define'");
	goto nope;
      }
      {
	struct arglist *otemp;

	for (otemp = temp->next; otemp != NULL; otemp = otemp->next)
	  if (temp->length == otemp->length &&
	    strncmp (temp->name, otemp->name, temp->length) == 0) {
	      U_CHAR *name;

	      name = (U_CHAR *) alloca (temp->length + 1);
	      (void) strncpy (name, temp->name, temp->length);
	      name[temp->length] = '\0';
	      cpp_error (pfile,
			 "duplicate argument name `%s' in `#define'", name);
	      goto nope;
	  }
      }
    }

    ++bp;			/* skip paren */
    SKIP_WHITE_SPACE (bp);
    /* now everything from bp before limit is the definition. */
    defn = collect_expansion (pfile, bp, limit, argno, arg_ptrs);
    defn->rest_args = rest_args;

    /* Now set defn->args.argnames to the result of concatenating
       the argument names in reverse order
       with comma-space between them.  */
    defn->args.argnames = (U_CHAR *) xmalloc (arglengths + 1);
    {
      struct arglist *temp;
      int i = 0;
      for (temp = arg_ptrs; temp; temp = temp->next) {
	bcopy (temp->name, &defn->args.argnames[i], temp->length);
	i += temp->length;
	if (temp->next != 0) {
	  defn->args.argnames[i++] = ',';
	  defn->args.argnames[i++] = ' ';
	}
      }
      defn->args.argnames[i] = 0;
    }
  } else {
    /* Simple expansion or empty definition.  */

    if (bp < limit)
      {
	if (is_hor_space[*bp]) {
	  bp++;
	  SKIP_WHITE_SPACE (bp);
	} else {
	  switch (*bp) {
	    case '!':  case '"':  case '#':  case '%':  case '&':  case '\'':
	    case ')':  case '*':  case '+':  case ',':  case '-':  case '.':
	    case '/':  case ':':  case ';':  case '<':  case '=':  case '>':
	    case '?':  case '[':  case '\\': case ']':  case '^':  case '{':
	    case '|':  case '}':  case '~':
	      cpp_warning (pfile, "missing white space after `#define %.*s'",
			   sym_length, symname);
	      break;

	    default:
	      cpp_pedwarn (pfile, "missing white space after `#define %.*s'",
			   sym_length, symname);
	      break;
	  }
	}
      }
    /* now everything from bp before limit is the definition. */
    defn = collect_expansion (pfile, bp, limit, -1, NULL_PTR);
    defn->args.argnames = (U_CHAR *) "";
  }

  defn->line = line;
  defn->file = file;

  /* OP is null if this is a predefinition */
  defn->predefined = predefinition;
  mdef.defn = defn;
  mdef.symnam = symname;
  mdef.symlen = sym_length;

  return mdef;

 nope:
  mdef.defn = 0;
  return mdef;
}

/* Check a purported macro name SYMNAME, and yield its length.
   USAGE is the kind of name this is intended for.  */

static int
check_macro_name (pfile, symname, usage)
     cpp_reader *pfile;
     U_CHAR *symname;
     char *usage;
{
  U_CHAR *p;
  int sym_length;

  for (p = symname; is_idchar[*p]; p++)
    ;
  sym_length = p - symname;
  if (sym_length == 0)
    cpp_error (pfile, "invalid %s name", usage);
  else if (!is_idstart[*symname]) {
    U_CHAR *msg;			/* what pain... */
    msg = (U_CHAR *) alloca (sym_length + 1);
    bcopy (symname, msg, sym_length);
    msg[sym_length] = 0;
    cpp_error (pfile, "invalid %s name `%s'", usage, msg);
  } else {
    if (! strncmp (symname, "defined", 7) && sym_length == 7)
      cpp_error (pfile, "invalid %s name `defined'", usage);
  }
  return sym_length;
}

/*
 * return zero if two DEFINITIONs are isomorphic
 */
static int
compare_defs (d1, d2)
     DEFINITION *d1, *d2;
{
  register struct reflist *a1, *a2;
  register U_CHAR *p1 = d1->expansion;
  register U_CHAR *p2 = d2->expansion;
  int first = 1;

  if (d1->nargs != d2->nargs)
    return 1;
  if (strcmp ((char *)d1->args.argnames, (char *)d2->args.argnames))
    return 1;
  for (a1 = d1->pattern, a2 = d2->pattern; a1 && a2;
       a1 = a1->next, a2 = a2->next) {
    if (!((a1->nchars == a2->nchars && ! strncmp (p1, p2, a1->nchars))
	  || ! comp_def_part (first, p1, a1->nchars, p2, a2->nchars, 0))
	|| a1->argno != a2->argno
	|| a1->stringify != a2->stringify
	|| a1->raw_before != a2->raw_before
	|| a1->raw_after != a2->raw_after)
      return 1;
    first = 0;
    p1 += a1->nchars;
    p2 += a2->nchars;
  }
  if (a1 != a2)
    return 1;
  if (comp_def_part (first, p1, d1->length - (p1 - d1->expansion),
		     p2, d2->length - (p2 - d2->expansion), 1))
    return 1;
  return 0;
}

/* Return 1 if two parts of two macro definitions are effectively different.
   One of the parts starts at BEG1 and has LEN1 chars;
   the other has LEN2 chars at BEG2.
   Any sequence of whitespace matches any other sequence of whitespace.
   FIRST means these parts are the first of a macro definition;
    so ignore leading whitespace entirely.
   LAST means these parts are the last of a macro definition;
    so ignore trailing whitespace entirely.  */

static int
comp_def_part (first, beg1, len1, beg2, len2, last)
     int first;
     U_CHAR *beg1, *beg2;
     int len1, len2;
     int last;
{
  register U_CHAR *end1 = beg1 + len1;
  register U_CHAR *end2 = beg2 + len2;
  if (first) {
    while (beg1 != end1 && is_space[*beg1]) beg1++;
    while (beg2 != end2 && is_space[*beg2]) beg2++;
  }
  if (last) {
    while (beg1 != end1 && is_space[end1[-1]]) end1--;
    while (beg2 != end2 && is_space[end2[-1]]) end2--;
  }
  while (beg1 != end1 && beg2 != end2) {
    if (is_space[*beg1] && is_space[*beg2]) {
      while (beg1 != end1 && is_space[*beg1]) beg1++;
      while (beg2 != end2 && is_space[*beg2]) beg2++;
    } else if (*beg1 == *beg2) {
      beg1++; beg2++;
    } else break;
  }
  return (beg1 != end1) || (beg2 != end2);
}

/* Process a #define command.
BUF points to the contents of the #define command, as a contiguous string.
LIMIT points to the first character past the end of the definition.
KEYWORD is the keyword-table entry for #define,
or NULL for a "predefined" macro.  */

static int
do_define (pfile, keyword, buf, limit)
     cpp_reader *pfile;
     struct directive *keyword;
     U_CHAR *buf, *limit;
{
  int hashcode;
  MACRODEF mdef;
  HASHNODE *hp;

#if 0
  /* If this is a precompiler run (with -pcp) pass thru #define commands.  */
  if (pcp_outfile && keyword)
    pass_thru_directive (buf, limit, pfile, keyword);
#endif

  mdef = create_definition (buf, limit, pfile, keyword == NULL);
  if (mdef.defn == 0)
    goto nope;

  hashcode = hashf (mdef.symnam, mdef.symlen, HASHSIZE);

  if ((hp = cpp_lookup (pfile, mdef.symnam, mdef.symlen, hashcode)) != NULL)
    {
      int ok = 0;
      /* Redefining a precompiled key is ok.  */
      if (hp->type == T_PCSTRING)
	ok = 1;
      /* Redefining a macro is ok if the definitions are the same.  */
      else if (hp->type == T_MACRO)
	ok = ! compare_defs (mdef.defn, hp->value.defn);
      /* Redefining a constant is ok with -D.  */
      else if (hp->type == T_CONST)
        ok = ! CPP_OPTIONS (pfile)->done_initializing;
      /* Print the warning if it's not ok.  */
      if (!ok)
	{
	  U_CHAR *msg;		/* what pain... */

	  /* If we are passing through #define and #undef directives, do
	     that for this re-definition now.  */
	  if (CPP_OPTIONS (pfile)->debug_output && keyword)
	    pass_thru_directive (buf, limit, pfile, keyword);

	  msg = (U_CHAR *) alloca (mdef.symlen + 22);
	  *msg = '`';
	  bcopy (mdef.symnam, msg + 1, mdef.symlen);
	  strcpy ((char *) (msg + mdef.symlen + 1), "' redefined");
	  cpp_pedwarn (pfile, msg);
	  if (hp->type == T_MACRO)
	    cpp_pedwarn_with_file_and_line (pfile, hp->value.defn->file, hp->value.defn->line,
				      "this is the location of the previous definition");
	}
      /* Replace the old definition.  */
      hp->type = T_MACRO;
      hp->value.defn = mdef.defn;
    }
  else
    {
      /* If we are passing through #define and #undef directives, do
	 that for this new definition now.  */
      if (CPP_OPTIONS (pfile)->debug_output && keyword)
	pass_thru_directive (buf, limit, pfile, keyword);
      install (mdef.symnam, mdef.symlen, T_MACRO, 0,
	       (char *) mdef.defn, hashcode);
    }

  return 0;

nope:

  return 1;
}

/* This structure represents one parsed argument in a macro call.
   `raw' points to the argument text as written (`raw_length' is its length).
   `expanded' points to the argument's macro-expansion
   (its length is `expand_length').
   `stringified_length' is the length the argument would have
   if stringified.
   `use_count' is the number of times this macro arg is substituted
   into the macro.  If the actual use count exceeds 10, 
   the value stored is 10. */

/* raw and expanded are relative to ARG_BASE */
#define ARG_BASE ((pfile)->token_buffer)

struct argdata {
  /* Strings relative to pfile->token_buffer */
  long raw, expanded, stringified;
  int raw_length, expand_length;
  int stringified_length;
  char newlines;
  char use_count;
};


cpp_buffer*
cpp_push_buffer (pfile, buffer, length)
     cpp_reader *pfile;
     U_CHAR *buffer;
     long length;
{
#ifdef STATIC_BUFFERS
  register cpp_buffer *buf = CPP_BUFFER (pfile);
  if (buf == pfile->buffer_stack)
    fatal ("%s: macro or `#include' recursion too deep", buf->fname);
  buf--;
  bzero ((char *) buf, sizeof (cpp_buffer));
  CPP_BUFFER (pfile) = buf;
#else
  register cpp_buffer *buf = (cpp_buffer*) xmalloc (sizeof(cpp_buffer));
  bzero ((char *) buf, sizeof (cpp_buffer));
  CPP_PREV_BUFFER (buf) = CPP_BUFFER (pfile);
  CPP_BUFFER (pfile) = buf;
#endif
  buf->if_stack = pfile->if_stack;
  buf->cleanup = null_cleanup;
  buf->underflow = null_underflow;
  buf->buf = buf->cur = buffer;
  buf->alimit = buf->rlimit = buffer + length;
  
  return buf;
}

cpp_buffer*
cpp_pop_buffer (pfile)
     cpp_reader *pfile;
{
  cpp_buffer *buf = CPP_BUFFER (pfile);
#ifdef STATIC_BUFFERS
  (*buf->cleanup) (buf, pfile);
  return ++CPP_BUFFER (pfile);
#else
  cpp_buffer *next_buf = CPP_PREV_BUFFER (buf);
  (*buf->cleanup) (buf, pfile);
  CPP_BUFFER (pfile) = next_buf;
  free (buf);
  return next_buf;
#endif
}

/* Scan until CPP_BUFFER (PFILE) is exhausted into PFILE->token_buffer.
   Pop the buffer when done. */

void
cpp_scan_buffer (pfile)
     cpp_reader *pfile;
{
  cpp_buffer *buffer = CPP_BUFFER (pfile);
  for (;;)
    {
      enum cpp_token token = cpp_get_token (pfile);
      if (token == CPP_EOF) /* Should not happen ... */
	break;
      if (token == CPP_POP && CPP_BUFFER (pfile) == buffer)
	{
	  cpp_pop_buffer (pfile);
	  break;
	}
    }
}

/*
 * Rescan a string (which may have escape marks) into pfile's buffer.
 * Place the result in pfile->token_buffer.
 *
 * The input is copied before it is scanned, so it is safe to pass
 * it something from the token_buffer that will get overwritten
 * (because it follows CPP_WRITTEN).  This is used by do_include.
 */

static void
cpp_expand_to_buffer (pfile, buf, length)
     cpp_reader *pfile;
     U_CHAR *buf;
     int length;
{
  register cpp_buffer *ip;
  cpp_buffer obuf;
  U_CHAR *limit = buf + length;
  U_CHAR *buf1;
#if 0
  int odepth = indepth;
#endif

  if (length < 0)
    abort ();

  /* Set up the input on the input stack.  */

  buf1 = (U_CHAR *) alloca (length + 1);
  {
    register U_CHAR *p1 = buf;
    register U_CHAR *p2 = buf1;

    while (p1 != limit)
      *p2++ = *p1++;
  }
  buf1[length] = 0;

  ip = cpp_push_buffer (pfile, buf1, length);
  ip->has_escapes = 1;
#if 0
  ip->lineno = obuf.lineno = 1;
#endif

  /* Scan the input, create the output.  */
  cpp_scan_buffer (pfile);

#if 0
  if (indepth != odepth)
    abort ();
#endif

  CPP_NUL_TERMINATE (pfile);
}


static void
adjust_position (buf, limit, linep, colp)
     U_CHAR *buf;
     U_CHAR *limit;