lex.c

gcc库的原代码,对编程有很大帮助.

    }
  while (c != matching_char);
}

static int nextyychar = YYEMPTY;
static YYSTYPE nextyylval;

struct pending_input {
  int nextchar, yychar, nextyychar, eof;
  YYSTYPE yylval, nextyylval;
  struct obstack token_obstack;
  int first_token;
};

struct pending_input *
save_pending_input ()
{
  struct pending_input *p;
  p = (struct pending_input *) xmalloc (sizeof (struct pending_input));
  p->nextchar = nextchar;
  p->yychar = yychar;
  p->nextyychar = nextyychar;
  p->yylval = yylval;
  p->nextyylval = nextyylval;
  p->eof = end_of_file;
  yychar = nextyychar = YYEMPTY;
  nextchar = -1;
  p->first_token = first_token;
  p->token_obstack = token_obstack;

  first_token = 0;
  gcc_obstack_init (&token_obstack);
  end_of_file = 0;
  return p;
}

void
restore_pending_input (p)
     struct pending_input *p;
{
  my_friendly_assert (nextchar == -1, 229);
  nextchar = p->nextchar;
  my_friendly_assert (yychar == YYEMPTY || yychar == END_OF_SAVED_INPUT, 230);
  yychar = p->yychar;
  my_friendly_assert (nextyychar == YYEMPTY, 231);
  nextyychar = p->nextyychar;
  yylval = p->yylval;
  nextyylval = p->nextyylval;
  first_token = p->first_token;
  obstack_free (&token_obstack, (char *) 0);
  token_obstack = p->token_obstack;
  end_of_file = p->eof;
  free (p);
}

/* Return next non-whitespace input character, which may come
   from `finput', or from `nextchar'.  */
static int
yynextch ()
{
  int c;

  if (nextchar >= 0)
    {
      c = nextchar;
      nextchar = -1;
    }
  else c = getch ();
  return skip_white_space (c);
}

/* Unget character CH from the input stream.
   If RESCAN is non-zero, then we want to `see' this
   character as the next input token.  */
void
yyungetc (ch, rescan)
     int ch;
     int rescan;
{
  /* Unget a character from the input stream.  */
  if (yychar == YYEMPTY || rescan == 0)
    {
      if (nextchar >= 0)
	put_back (nextchar);
      nextchar = ch;
    }
  else
    {
      my_friendly_assert (nextyychar == YYEMPTY, 232);
      nextyychar = yychar;
      nextyylval = yylval;
      yychar = ch;
    }
}

/* This function stores away the text for an inline function that should
   be processed later.  It decides how much later, and may need to move
   the info between obstacks; therefore, the caller should not refer to
   the T parameter after calling this function.

   This function also stores the list of template-parameter bindings that
   will be needed for expanding the template, if any.  */

static void
store_pending_inline (decl, t)
     tree decl;
     struct pending_inline *t;
{
  extern int processing_template_defn;
  int delay_to_eof = 0;
  struct pending_inline **inlines;

  t->fndecl = decl;
  /* Default: compile right away, and no extra bindings are needed.  */
  t->parm_vec = t->bindings = 0;
  if (processing_template_defn)
    {
      tree type = current_class_type;
      /* Assumption: In this (possibly) nested class sequence, only
	 one name will have template parms.  */
      while (type && TREE_CODE_CLASS (TREE_CODE (type)) == 't')
	{
	  tree decl = TYPE_NAME (type);
	  tree tmpl = IDENTIFIER_TEMPLATE (DECL_NAME (decl));
	  if (tmpl)
	    {
	      t->parm_vec = DECL_TEMPLATE_INFO (TREE_PURPOSE (tmpl))->parm_vec;
	      t->bindings = TREE_VALUE (tmpl);
	    }
	  type = DECL_CONTEXT (decl);
	}
      if (TREE_CODE (TREE_TYPE (decl)) == METHOD_TYPE
	  || TREE_CODE (TREE_TYPE (decl)) == FUNCTION_TYPE)
	{
	  if (TREE_CODE (TREE_TYPE (decl)) == METHOD_TYPE)
	    my_friendly_assert (TYPE_MAX_VALUE (TREE_TYPE (decl)) == current_class_type,
				233);

	  /* Inline functions can be compiled immediately.  Other functions
	     will be output separately, so if we're in interface-only mode,
	     punt them now, or output them now if we're doing implementations
	     and we know no overrides will exist.  Otherwise, we delay until
	     end-of-file, to see if the definition is really required.  */
	  if (DECL_THIS_INLINE (decl))
	    /* delay_to_eof == 0 */;
	  else if (current_class_type && !interface_unknown)
	    {
	      if (interface_only)
		{
#if 0
		  print_node_brief (stderr, "\ndiscarding text for ", decl, 0);
#endif
		  if (t->can_free)
		    obstack_free (&inline_text_obstack, t->buf);
		  DECL_PENDING_INLINE_INFO (decl) = 0;
		  return;
		}
	    }
	  /* Don't delay the processing of virtual functions.  */
	  else if (DECL_VINDEX (decl) == NULL_TREE)
	    delay_to_eof = 1;
	}
      else
	my_friendly_abort (58);
    }

  if (delay_to_eof)
    {
      extern struct pending_inline *pending_template_expansions;

      if (t->can_free)
	{
	  char *free_to = t->buf;
	  t->buf = (char *) obstack_copy (&permanent_obstack, t->buf,
					  t->len + 1);
	  t = (struct pending_inline *) obstack_copy (&permanent_obstack, 
						      (char *)t, sizeof (*t));
	  obstack_free (&inline_text_obstack, free_to);
	}
      inlines = &pending_template_expansions;
      t->can_free = 0;
    }
  else
    {
      inlines = &pending_inlines;
      DECL_PENDING_INLINE_INFO (decl) = t;
    }

  /* Because we use obstacks, we must process these in precise order.  */
  t->next = *inlines;
  *inlines = t;
}

void reinit_parse_for_block ();

void
reinit_parse_for_method (yychar, decl)
     int yychar;
     tree decl;
{
  int len;
  int starting_lineno = lineno;
  char *starting_filename = input_filename;

  reinit_parse_for_block (yychar, &inline_text_obstack, 0);

  len = obstack_object_size (&inline_text_obstack);
  current_base_init_list = NULL_TREE;
  current_member_init_list = NULL_TREE;
  if (decl == void_type_node
      || (current_class_type && TYPE_REDEFINED (current_class_type)))
    {
      /* Happens when we get two declarations of the same
	 function in the same scope.  */
      char *buf = obstack_finish (&inline_text_obstack);
      obstack_free (&inline_text_obstack, buf);
      return;
    }
  else
    {
      struct pending_inline *t;
      char *buf = obstack_finish (&inline_text_obstack);

      t = (struct pending_inline *) obstack_alloc (&inline_text_obstack,
						   sizeof (struct pending_inline));
      t->lineno = starting_lineno;
      t->filename = starting_filename;
      t->token = YYEMPTY;
      t->token_value = 0;
      t->buf = buf;
      t->len = len;
      t->can_free = 1;
      t->deja_vu = 0;
      if (interface_unknown && processing_template_defn && flag_external_templates && ! DECL_IN_SYSTEM_HEADER (decl))
	warn_if_unknown_interface (decl);
      t->interface = (interface_unknown ? 1 : (interface_only ? 0 : 2));
      store_pending_inline (decl, t);
    }
}

/* Consume a block -- actually, a method or template definition beginning
   with `:' or `{' -- and save it away on the specified obstack.

   Argument IS_TEMPLATE indicates which set of error messages should be
   output if something goes wrong.  This should really be cleaned up somehow,
   without loss of clarity.  */
void
reinit_parse_for_block (pyychar, obstackp, is_template)
     int pyychar;
     struct obstack *obstackp;
     int is_template;
{
  register int c = 0;
  int blev = 1;
  int starting_lineno = lineno;
  char *starting_filename = input_filename;
  int len;
  int look_for_semicolon = 0;
  int look_for_lbrac = 0;

  if (pyychar == '{')
    obstack_1grow (obstackp, '{');
  else if (pyychar == '=')
    look_for_semicolon = 1;
  else if (pyychar == ':')
    {
      obstack_1grow (obstackp, pyychar);
      look_for_lbrac = 1;
      blev = 0;
    }
  else if (pyychar == RETURN && !is_template)
    {
      obstack_grow (obstackp, "return", 6);
      look_for_lbrac = 1;
      blev = 0;
    }
  else if (pyychar == TRY && !is_template)
    {
      obstack_grow (obstackp, "try", 3);
      look_for_lbrac = 1;
      blev = 0;
    }
  else
    {
      yyerror (is_template
	       ? "parse error in template specification"
	       : "parse error in method specification");
      obstack_1grow (obstackp, '{');
    }

  if (nextchar != EOF)
    {
      c = nextchar;
      nextchar = EOF;
    }
  else
    c = getch ();
  
  while (c != EOF)
    {
      int this_lineno = lineno;

      c = skip_white_space (c);

      /* Don't lose our cool if there are lots of comments.  */
      if (lineno == this_lineno + 1)
	obstack_1grow (obstackp, '\n');
      else if (lineno == this_lineno)
	;
      else if (lineno - this_lineno < 10)
	{
	  int i;
	  for (i = lineno - this_lineno; i > 0; i--)
	    obstack_1grow (obstackp, '\n');
	}
      else
	{
	  char buf[16];
	  sprintf (buf, "\n# %d \"", lineno);
	  len = strlen (buf);
	  obstack_grow (obstackp, buf, len);

	  len = strlen (input_filename);
	  obstack_grow (obstackp, input_filename, len);
	  obstack_1grow (obstackp, '\"');
	  obstack_1grow (obstackp, '\n');
	}

      while (c > ' ')		/* ASCII dependent...  */
	{
	  obstack_1grow (obstackp, c);
	  if (c == '{')
	    {
	      look_for_lbrac = 0;
	      blev++;
	    }
	  else if (c == '}')
	    {
	      blev--;
	      if (blev == 0 && !look_for_semicolon)
		{
		  if (pyychar == TRY)
		    {
		      if (peekyylex () == CATCH)
			{
			  yylex ();
			  obstack_grow (obstackp, " catch ", 7);
			  look_for_lbrac = 1;
			}
		      else
			{
			  yychar = '{';
			  goto done;
			}
		    }
		  else
		    {
		      goto done;
		    }
		}
	    }
	  else if (c == '\\')
	    {
	      /* Don't act on the next character...e.g, doing an escaped
		 double-quote.  */
	      c = getch ();
	      if (c == EOF)
		{
		  error_with_file_and_line (starting_filename,
					    starting_lineno,
					    "end of file read inside definition");
		  goto done;
		}
	      obstack_1grow (obstackp, c);
	    }
	  else if (c == '\"')
	    consume_string (obstackp, c);
	  else if (c == '\'')
	    consume_string (obstackp, c);
	  else if (c == ';')
	    {
	      if (look_for_lbrac)
		{
		  error (is_template
			 ? "template body missing"
			 : "function body for constructor missing");
		  obstack_1grow (obstackp, '{');
		  obstack_1grow (obstackp, '}');
		  len += 2;
		  goto done;
		}
	      else if (look_for_semicolon && blev == 0)
		goto done;
	    }
	  c = getch ();
	}

      if (c == EOF)
	{
	  error_with_file_and_line (starting_filename,
				    starting_lineno,
				    "end of file read inside definition");
	  goto done;
	}
      else if (c != '\n')
	{
	  obstack_1grow (obstackp, c);
	  c = getch ();
	}
    }
 done:
  obstack_1grow (obstackp, '\0');
}

/* Build a default function named NAME for type TYPE.
   KIND says what to build.

   When KIND == 0, build default destructor.
   When KIND == 1, build virtual destructor.
   When KIND == 2, build default constructor.
   When KIND == 3, build default X(const X&) constructor.
   When KIND == 4, build default X(X&) constructor.
   When KIND == 5, build default operator = (const X&).
   When KIND == 6, build default operator = (X&).  */

tree
cons_up_default_function (type, full_name, kind)
     tree type, full_name;
     int kind;
{
  extern tree void_list_node;
  char *func_buf = NULL;
  int func_len = 0;
  tree declspecs = NULL_TREE;
  tree fn, args;
  tree argtype;
  int retref = 0;
  int complex = 0;