pt.c

gcc-2.95.3 Linux下最常用的C编译器

		      type);
      tree t
	= build_template_parm_index (TEMPLATE_PARM_IDX (index),
				     TEMPLATE_PARM_LEVEL (index) - levels,
				     TEMPLATE_PARM_ORIG_LEVEL (index),
				     decl, type);
      TEMPLATE_PARM_DESCENDANTS (index) = t;

      /* Template template parameters need this.  */
      DECL_TEMPLATE_PARMS (decl)
	= DECL_TEMPLATE_PARMS (TEMPLATE_PARM_DECL (index));
    }

  return TEMPLATE_PARM_DESCENDANTS (index);
}

/* Process information from new template parameter NEXT and append it to the
   LIST being built.  */

tree
process_template_parm (list, next)
     tree list, next;
{
  tree parm;
  tree decl = 0;
  tree defval;
  int is_type, idx;

  parm = next;
  my_friendly_assert (TREE_CODE (parm) == TREE_LIST, 259);
  defval = TREE_PURPOSE (parm);
  parm = TREE_VALUE (parm);
  is_type = TREE_PURPOSE (parm) == class_type_node;

  if (list)
    {
      tree p = TREE_VALUE (tree_last (list));

      if (TREE_CODE (p) == TYPE_DECL)
	idx = TEMPLATE_TYPE_IDX (TREE_TYPE (p));
      else if (TREE_CODE (p) == TEMPLATE_DECL)
	idx = TEMPLATE_TYPE_IDX (TREE_TYPE (DECL_TEMPLATE_RESULT (p)));
      else
	idx = TEMPLATE_PARM_IDX (DECL_INITIAL (p));
      ++idx;
    }
  else
    idx = 0;

  if (!is_type)
    {
      my_friendly_assert (TREE_CODE (TREE_PURPOSE (parm)) == TREE_LIST, 260);
      /* is a const-param */
      parm = grokdeclarator (TREE_VALUE (parm), TREE_PURPOSE (parm),
			     PARM, 0, NULL_TREE);

      /* [temp.param]

	 The top-level cv-qualifiers on the template-parameter are
	 ignored when determining its type.  */
      TREE_TYPE (parm) = TYPE_MAIN_VARIANT (TREE_TYPE (parm));

      /* A template parameter is not modifiable.  */
      TREE_READONLY (parm) = 1;
      if (IS_AGGR_TYPE (TREE_TYPE (parm))
	  && TREE_CODE (TREE_TYPE (parm)) != TEMPLATE_TYPE_PARM
	  && TREE_CODE (TREE_TYPE (parm)) != TYPENAME_TYPE)
	{
	  cp_error ("`%#T' is not a valid type for a template constant parameter",
		    TREE_TYPE (parm));
	  if (DECL_NAME (parm) == NULL_TREE)
	    error ("  a template type parameter must begin with `class' or `typename'");
	  TREE_TYPE (parm) = void_type_node;
	}
      else if (pedantic
	       && (TREE_CODE (TREE_TYPE (parm)) == REAL_TYPE
		   || TREE_CODE (TREE_TYPE (parm)) == COMPLEX_TYPE))
	cp_pedwarn ("`%T' is not a valid type for a template constant parameter",
		    TREE_TYPE (parm));
      if (TREE_PERMANENT (parm) == 0)
        {
	  parm = copy_node (parm);
	  TREE_PERMANENT (parm) = 1;
        }
      decl = build_decl (CONST_DECL, DECL_NAME (parm), TREE_TYPE (parm));
      DECL_INITIAL (parm) = DECL_INITIAL (decl) 
	= build_template_parm_index (idx, processing_template_decl,
				     processing_template_decl,
				     decl, TREE_TYPE (parm));
    }
  else
    {
      tree t;
      parm = TREE_VALUE (parm);
      
      if (parm && TREE_CODE (parm) == TEMPLATE_DECL)
	{
	  t = make_lang_type (TEMPLATE_TEMPLATE_PARM);
	  /* This is for distinguishing between real templates and template 
	     template parameters */
	  TREE_TYPE (parm) = t;
	  TREE_TYPE (DECL_TEMPLATE_RESULT (parm)) = t;
	  decl = parm;
	}
      else
	{
	  t = make_lang_type (TEMPLATE_TYPE_PARM);
	  /* parm is either IDENTIFIER_NODE or NULL_TREE */
	  decl = build_decl (TYPE_DECL, parm, t);
	}
        
      TYPE_NAME (t) = decl;
      TYPE_STUB_DECL (t) = decl;
      parm = decl;
      TEMPLATE_TYPE_PARM_INDEX (t)
	= build_template_parm_index (idx, processing_template_decl, 
				     processing_template_decl,
				     decl, TREE_TYPE (parm));
    }
  SET_DECL_ARTIFICIAL (decl);
  DECL_TEMPLATE_PARM_P (decl) = 1;
  pushdecl (decl);
  parm = build_tree_list (defval, parm);
  return chainon (list, parm);
}

/* The end of a template parameter list has been reached.  Process the
   tree list into a parameter vector, converting each parameter into a more
   useful form.	 Type parameters are saved as IDENTIFIER_NODEs, and others
   as PARM_DECLs.  */

tree
end_template_parm_list (parms)
     tree parms;
{
  int nparms;
  tree parm;
  tree saved_parmlist = make_tree_vec (list_length (parms));

  current_template_parms
    = tree_cons (build_int_2 (0, processing_template_decl),
		 saved_parmlist, current_template_parms);

  for (parm = parms, nparms = 0; parm; parm = TREE_CHAIN (parm), nparms++)
    TREE_VEC_ELT (saved_parmlist, nparms) = parm;

  --processing_template_parmlist;

  return saved_parmlist;
}

/* end_template_decl is called after a template declaration is seen.  */

void
end_template_decl ()
{
  reset_specialization ();

  if (! processing_template_decl)
    return;

  /* This matches the pushlevel in begin_template_parm_list.  */
  poplevel (0, 0, 0);

  --processing_template_decl;
  current_template_parms = TREE_CHAIN (current_template_parms);
  (void) get_pending_sizes ();	/* Why? */
}

/* Given a template argument vector containing the template PARMS.
   The innermost PARMS are given first.  */

tree
current_template_args ()
{
  tree header;
  tree args = NULL_TREE;
  int length = TMPL_PARMS_DEPTH (current_template_parms);
  int l = length;

  /* If there is only one level of template parameters, we do not
     create a TREE_VEC of TREE_VECs.  Instead, we return a single
     TREE_VEC containing the arguments.  */
  if (length > 1)
    args = make_tree_vec (length);

  for (header = current_template_parms; header; header = TREE_CHAIN (header))
    {
      tree a = copy_node (TREE_VALUE (header));
      int i;

      TREE_TYPE (a) = NULL_TREE;
      for (i = TREE_VEC_LENGTH (a) - 1; i >= 0; --i)
	{
	  tree t = TREE_VEC_ELT (a, i);

	  /* T will be a list if we are called from within a
	     begin/end_template_parm_list pair, but a vector directly
	     if within a begin/end_member_template_processing pair.  */
	  if (TREE_CODE (t) == TREE_LIST) 
	    {
	      t = TREE_VALUE (t);
	      
	      if (TREE_CODE (t) == TYPE_DECL 
		  || TREE_CODE (t) == TEMPLATE_DECL)
		t = TREE_TYPE (t);
	      else
		t = DECL_INITIAL (t);
	      TREE_VEC_ELT (a, i) = t;
	    }
	}

      if (length > 1)
	TREE_VEC_ELT (args, --l) = a;
      else
	args = a;
    }

  return args;
}

/* Return a TEMPLATE_DECL corresponding to DECL, using the indicated
   template PARMS.  Used by push_template_decl below.  */

static tree
build_template_decl (decl, parms)
     tree decl;
     tree parms;
{
  tree tmpl = build_lang_decl (TEMPLATE_DECL, DECL_NAME (decl), NULL_TREE);
  DECL_TEMPLATE_PARMS (tmpl) = parms;
  DECL_CONTEXT (tmpl) = DECL_CONTEXT (decl);
  if (DECL_LANG_SPECIFIC (decl))
    {
      DECL_CLASS_CONTEXT (tmpl) = DECL_CLASS_CONTEXT (decl);
      DECL_STATIC_FUNCTION_P (tmpl) = DECL_STATIC_FUNCTION_P (decl);
      DECL_CONSTRUCTOR_P (tmpl) = DECL_CONSTRUCTOR_P (decl);
    }

  return tmpl;
}

struct template_parm_data
{
  /* The level of the template parameters we are currently
     processing.  */
  int level;

  /* The index of the specialization argument we are currently
     processing.  */
  int current_arg;

  /* An array whose size is the number of template parameters.  The
     elements are non-zero if the parameter has been used in any one
     of the arguments processed so far.  */
  int* parms;

  /* An array whose size is the number of template arguments.  The
     elements are non-zero if the argument makes use of template
     parameters of this level.  */
  int* arg_uses_template_parms;
};

/* Subroutine of push_template_decl used to see if each template
   parameter in a partial specialization is used in the explicit
   argument list.  If T is of the LEVEL given in DATA (which is
   treated as a template_parm_data*), then DATA->PARMS is marked
   appropriately.  */

static int
mark_template_parm (t, data)
     tree t;
     void* data;
{
  int level;
  int idx;
  struct template_parm_data* tpd = (struct template_parm_data*) data;

  if (TREE_CODE (t) == TEMPLATE_PARM_INDEX)
    {
      level = TEMPLATE_PARM_LEVEL (t);
      idx = TEMPLATE_PARM_IDX (t);
    }
  else
    {
      level = TEMPLATE_TYPE_LEVEL (t);
      idx = TEMPLATE_TYPE_IDX (t);
    }

  if (level == tpd->level)
    {
      tpd->parms[idx] = 1;
      tpd->arg_uses_template_parms[tpd->current_arg] = 1;
    }

  /* Return zero so that for_each_template_parm will continue the
     traversal of the tree; we want to mark *every* template parm.  */
  return 0;
}

/* Process the partial specialization DECL.  */

static tree
process_partial_specialization (decl)
     tree decl;
{
  tree type = TREE_TYPE (decl);
  tree maintmpl = CLASSTYPE_TI_TEMPLATE (type);
  tree specargs = CLASSTYPE_TI_ARGS (type);
  tree inner_args = innermost_args (specargs);
  tree inner_parms = INNERMOST_TEMPLATE_PARMS (current_template_parms);
  tree main_inner_parms = DECL_INNERMOST_TEMPLATE_PARMS (maintmpl);
  int nargs = TREE_VEC_LENGTH (inner_args);
  int ntparms = TREE_VEC_LENGTH (inner_parms);
  int  i;
  int did_error_intro = 0;
  struct template_parm_data tpd;
  struct template_parm_data tpd2;

  /* We check that each of the template parameters given in the
     partial specialization is used in the argument list to the
     specialization.  For example:

       template <class T> struct S;
       template <class T> struct S<T*>;

     The second declaration is OK because `T*' uses the template
     parameter T, whereas

       template <class T> struct S<int>;

     is no good.  Even trickier is:

       template <class T>
       struct S1
       {
	  template <class U>
	  struct S2;
	  template <class U>
	  struct S2<T>;
       };

     The S2<T> declaration is actually illegal; it is a
     full-specialization.  Of course, 

	  template <class U>
	  struct S2<T (*)(U)>;

     or some such would have been OK.  */
  tpd.level = TMPL_PARMS_DEPTH (current_template_parms);
  tpd.parms = alloca (sizeof (int) * ntparms);
  bzero ((PTR) tpd.parms, sizeof (int) * ntparms);

  tpd.arg_uses_template_parms = alloca (sizeof (int) * nargs);
  bzero ((PTR) tpd.arg_uses_template_parms, sizeof (int) * nargs);
  for (i = 0; i < nargs; ++i)
    {
      tpd.current_arg = i;
      for_each_template_parm (TREE_VEC_ELT (inner_args, i),
			      &mark_template_parm,
			      &tpd);
    }
  for (i = 0; i < ntparms; ++i)
    if (tpd.parms[i] == 0)
      {
	/* One of the template parms was not used in the
           specialization.  */
	if (!did_error_intro)
	  {
	    cp_error ("template parameters not used in partial specialization:");
	    did_error_intro = 1;
	  }

	cp_error ("        `%D'", 
		  TREE_VALUE (TREE_VEC_ELT (inner_parms, i)));
      }

  /* [temp.class.spec]

     The argument list of the specialization shall not be identical to
     the implicit argument list of the primary template.  */
  if (comp_template_args (inner_args, 
			  innermost_args (CLASSTYPE_TI_ARGS (TREE_TYPE
							     (maintmpl)))))
    cp_error ("partial specialization `%T' does not specialize any template arguments", type);

  /* [temp.class.spec]

     A partially specialized non-type argument expression shall not
     involve template parameters of the partial specialization except
     when the argument expression is a simple identifier.

     The type of a template parameter corresponding to a specialized
     non-type argument shall not be dependent on a parameter of the
     specialization.  */
  my_friendly_assert (nargs == DECL_NTPARMS (maintmpl), 0);
  tpd2.parms = 0;
  for (i = 0; i < nargs; ++i)
    {
      tree arg = TREE_VEC_ELT (inner_args, i);
      if (/* These first two lines are the `non-type' bit.  */
	  TREE_CODE_CLASS (TREE_CODE (arg)) != 't'
	  && TREE_CODE (arg) != TEMPLATE_DECL
	  /* This next line is the `argument expression is not just a
	     simple identifier' condition and also the `specialized
	     non-type argument' bit.  */
	  && TREE_CODE (arg) != TEMPLATE_PARM_INDEX)
	{
	  if (tpd.arg_uses_template_parms[i])
	    cp_error ("template argument `%E' involves template parameter(s)", arg);
	  else 
	    {
	      /* Look at the corresponding template parameter,
		 marking which template parameters its type depends
		 upon.  */
	      tree type = 
		TREE_TYPE (TREE_VALUE (TREE_VEC_ELT (main_inner_parms, 
						     i)));

	      if (!tpd2.parms)
		{
		  /* We haven't yet initialized TPD2.  Do so now.  */
		  tpd2.arg_uses_template_parms 
		    =  (int*) alloca (sizeof (int) * nargs);
		  /* The number of parameters here is the number in the
		     m