pt.c

gcc库的原代码,对编程有很大帮助.

static struct tinst_level *free_tinst_level = 0;
static int tinst_depth = 0;
int max_tinst_depth = 17;

int
push_tinst_level (name)
     tree name;
{
  struct tinst_level *new;
  tree global = IDENTIFIER_GLOBAL_VALUE (name);

  if (tinst_depth >= max_tinst_depth)
    {
      error ("template instantiation depth exceeds maximum of %d",
	     max_tinst_depth);
      cp_error ("  instantiating `%D'", name);
      return 0;
    }

  if (free_tinst_level)
    {
      new = free_tinst_level;
      free_tinst_level = new->next;
    }
  else
    new = (struct tinst_level *) xmalloc (sizeof (struct tinst_level));

  new->classname = name;
  if (global)
    {
      new->line = DECL_SOURCE_LINE (global);
      new->file = DECL_SOURCE_FILE (global);
    }
  else
    {
      new->line = lineno;
      new->file = input_filename;
    }
  new->next = current_tinst_level;
  current_tinst_level = new;
  ++tinst_depth;
  return 1;
}

void
pop_tinst_level ()
{
  struct tinst_level *old = current_tinst_level;

  current_tinst_level = old->next;
  old->next = free_tinst_level;
  free_tinst_level = old;
  --tinst_depth;
}

struct tinst_level *
tinst_for_decl ()
{
  struct tinst_level *p = current_tinst_level;

  if (p)
    for (; p->next ; p = p->next )
      ;
  return p;
}

tree
instantiate_class_template (classname, setup_parse)
     tree classname;
     int setup_parse;
{
  struct template_info *template_info;
  tree template, t1;

  if (classname == error_mark_node)
    return error_mark_node;

  my_friendly_assert (TREE_CODE (classname) == IDENTIFIER_NODE, 278);
  template = IDENTIFIER_TEMPLATE (classname);

  if (IDENTIFIER_HAS_TYPE_VALUE (classname))
    {
      tree type = IDENTIFIER_TYPE_VALUE (classname);
      if (TREE_CODE (type) == UNINSTANTIATED_P_TYPE)
	return type;
      if (TYPE_BEING_DEFINED (type)
	  || TYPE_SIZE (type)
	  || CLASSTYPE_USE_TEMPLATE (type) != 0)
	return type;
    }

  /* If IDENTIFIER_LOCAL_VALUE is already set on this template classname
     (it's something like `foo<int>'), that means we're already working on
     the instantiation for it.  Normally, a classname comes in with nothing
     but its IDENTIFIER_TEMPLATE slot set.  If we were to try to instantiate
     this again, we'd get a redeclaration error.  Since we're already working
     on it, we'll pass back this classname's TYPE_DECL (it's the value of
     the classname's IDENTIFIER_LOCAL_VALUE).  Only do this if we're setting
     things up for the parser, though---if we're just trying to instantiate
     it (e.g., via tsubst) we can trip up cuz it may not have an
     IDENTIFIER_TYPE_VALUE when it will need one.  */
  if (setup_parse && IDENTIFIER_LOCAL_VALUE (classname))
    return IDENTIFIER_LOCAL_VALUE (classname);

  if (uses_template_parms (classname))
    {
      if (!TREE_TYPE (classname))
	{
	  tree t = make_lang_type (RECORD_TYPE);
	  tree d = build_decl (TYPE_DECL, classname, t);
	  DECL_NAME (d) = classname;
	  TYPE_NAME (t) = d;
	  pushdecl (d);
	}
      return NULL_TREE;
    }

  t1 = TREE_PURPOSE (template);
  my_friendly_assert (TREE_CODE (t1) == TEMPLATE_DECL, 279);

  /* If a template is declared but not defined, accept it; don't crash.
     Later uses requiring the definition will be flagged as errors by
     other code.  Thanks to [e-mail] for this bug fix.  */
  if (DECL_TEMPLATE_INFO (t1)->text == 0)
    setup_parse = 0;

  push_to_top_level ();
  template_info = DECL_TEMPLATE_INFO (t1);
  if (setup_parse && push_tinst_level (classname))
    {
      push_template_decls (DECL_TEMPLATE_PARMS (TREE_PURPOSE (template)),
			   TREE_VALUE (template), 0);
      set_current_level_tags_transparency (1);
      feed_input (template_info->text, template_info->length, (struct obstack *)0);
      lineno = template_info->lineno;
      input_filename = template_info->filename;
      /* Get interface/implementation back in sync.  */
      extract_interface_info ();
      overload_template_name (classname, 0);
      /* Kludge so that we don't get screwed by our own base classes.  */
      TYPE_BEING_DEFINED (TREE_TYPE (classname)) = 1;
      yychar = PRE_PARSED_CLASS_DECL;
      yylval.ttype = classname;
      processing_template_defn++;
      if (!flag_external_templates)
	interface_unknown++;
      template_classes
	= perm_tree_cons (classname, NULL_TREE, template_classes);
    }
  else
    {
      tree t, decl, id, tmpl;

      id = classname;
      tmpl = TREE_PURPOSE (IDENTIFIER_TEMPLATE (id));
      t = xref_tag (DECL_TEMPLATE_INFO (tmpl)->aggr, id, NULL_TREE, 0);
      my_friendly_assert (TREE_CODE (t) == RECORD_TYPE
			  || TREE_CODE (t) == UNION_TYPE, 280);

      /* Now, put a copy of the decl in global scope, to avoid
       * recursive expansion.  */
      decl = IDENTIFIER_LOCAL_VALUE (id);
      if (!decl)
	decl = IDENTIFIER_CLASS_VALUE (id);
      if (decl)
	{
	  my_friendly_assert (TREE_CODE (decl) == TYPE_DECL, 281);
	  /* We'd better make sure we're on the permanent obstack or else
	   * we'll get a "friendly" abort 124 in pushdecl.  Perhaps a
	   * copy_to_permanent would be sufficient here, but then a
	   * sharing problem might occur.  I don't know -- [e-mail] */
	  push_obstacks (&permanent_obstack, &permanent_obstack);
	  pushdecl_top_level (copy_node (decl));
	  pop_obstacks ();
	}
      pop_from_top_level ();
    }

  return NULL_TREE;
}

static int
list_eq (t1, t2)
     tree t1, t2;
{
  if (t1 == NULL_TREE)
    return t2 == NULL_TREE;
  if (t2 == NULL_TREE)
    return 0;
  /* Don't care if one declares its arg const and the other doesn't -- the
     main variant of the arg type is all that matters.  */
  if (TYPE_MAIN_VARIANT (TREE_VALUE (t1))
      != TYPE_MAIN_VARIANT (TREE_VALUE (t2)))
    return 0;
  return list_eq (TREE_CHAIN (t1), TREE_CHAIN (t2));
}

static tree 
lookup_nested_type_by_name (ctype, name)
        tree ctype, name;
{
  tree t;

  for (t = CLASSTYPE_TAGS (ctype); t; t = TREE_CHAIN (t))
    {
      if (name == TREE_PURPOSE (t))
	return TREE_VALUE (t);
    }
  return NULL_TREE;
}

static tree
search_nested_type_in_tmpl (tmpl, type)
        tree tmpl, type;
{
  tree t;

  if (tmpl == NULL || TYPE_CONTEXT(type) == NULL)
    return tmpl;
  t = search_nested_type_in_tmpl (tmpl, TYPE_CONTEXT(type));
  if (t == NULL) return t;
  t = lookup_nested_type_by_name(t, DECL_NAME(TYPE_NAME(type)));
  return t;
}

tree
tsubst (t, args, nargs, in_decl)
     tree t, *args;
     int nargs;
     tree in_decl;
{
  tree type;

  if (t == NULL_TREE || t == error_mark_node)
    return t;

  type = TREE_TYPE (t);
  if (type
      /* Minor optimization.
	 ?? Are these really the most frequent cases?  Is the savings
	 significant?  */
      && type != integer_type_node
      && type != void_type_node
      && type != char_type_node)
    type = tsubst (type, args, nargs, in_decl);

  switch (TREE_CODE (t))
    {
    case RECORD_TYPE:
      if (TYPE_PTRMEMFUNC_P (t))
	return build_ptrmemfunc_type
	  (tsubst (TYPE_PTRMEMFUNC_FN_TYPE (t), args, nargs, in_decl));
	  
      /* else fall through */

    case ERROR_MARK:
    case IDENTIFIER_NODE:
    case OP_IDENTIFIER:
    case VOID_TYPE:
    case REAL_TYPE:
    case ENUMERAL_TYPE:
    case BOOLEAN_TYPE:
    case INTEGER_CST:
    case REAL_CST:
    case STRING_CST:
    case UNION_TYPE:
      return t;

    case INTEGER_TYPE:
      if (t == integer_type_node)
	return t;

      if (TREE_CODE (TYPE_MIN_VALUE (t)) == INTEGER_CST
	  && TREE_CODE (TYPE_MAX_VALUE (t)) == INTEGER_CST)
	return t;
      return build_index_2_type
	(tsubst (TYPE_MIN_VALUE (t), args, nargs, in_decl),
	 tsubst (TYPE_MAX_VALUE (t), args, nargs, in_decl));

    case TEMPLATE_TYPE_PARM:
      {
	tree arg = args[TEMPLATE_TYPE_IDX (t)];
	return cp_build_type_variant
	  (arg, TYPE_READONLY (arg) || TYPE_READONLY (t),
	   TYPE_VOLATILE (arg) || TYPE_VOLATILE (t));
      }

    case TEMPLATE_CONST_PARM:
      return args[TEMPLATE_CONST_IDX (t)];

    case FUNCTION_DECL:
      {
	tree r;
	tree fnargs, result;
	
	if (type == TREE_TYPE (t)
	    && (DECL_CONTEXT (t) == NULL_TREE
		|| TREE_CODE_CLASS (TREE_CODE (DECL_CONTEXT (t))) != 't'))
	  return t;
	fnargs = tsubst (DECL_ARGUMENTS (t), args, nargs, t);
	result = tsubst (DECL_RESULT (t), args, nargs, t);
	if (DECL_CONTEXT (t) != NULL_TREE
	    && TREE_CODE_CLASS (TREE_CODE (DECL_CONTEXT (t))) == 't')
	  {
	    /* Look it up in that class, and return the decl node there,
	       instead of creating a new one.  */
	    tree ctx, methods, name, method;
	    int n_methods;
	    int i, found = 0;

	    name = DECL_NAME (t);
	    ctx = tsubst (DECL_CONTEXT (t), args, nargs, t);
	    methods = CLASSTYPE_METHOD_VEC (ctx);
	    if (methods == NULL_TREE)
	      /* No methods at all -- no way this one can match.  */
	      goto no_match;
	    n_methods = TREE_VEC_LENGTH (methods);

	    r = NULL_TREE;

	    if (!strncmp (OPERATOR_TYPENAME_FORMAT,
			  IDENTIFIER_POINTER (name),
			  sizeof (OPERATOR_TYPENAME_FORMAT) - 1))
	      {
		/* Type-conversion operator.  Reconstruct the name, in
		   case it's the name of one of the template's parameters.  */
		name = build_typename_overload (TREE_TYPE (type));
	      }

	    if (DECL_CONTEXT (t) != NULL_TREE
		&& TREE_CODE_CLASS (TREE_CODE (DECL_CONTEXT (t))) == 't'
		&& constructor_name (DECL_CONTEXT (t)) == DECL_NAME (t))
	      name = constructor_name (ctx);

	    if (DECL_CONSTRUCTOR_P (t) && TYPE_USES_VIRTUAL_BASECLASSES (ctx))
	      {
		/* Since we didn't know that this class had virtual bases until after
		   we instantiated it, we have to recreate the arguments to this
		   constructor, as otherwise it would miss the __in_chrg parameter.  */
		tree newtype, parm;
		tree parms = TREE_CHAIN (TYPE_ARG_TYPES (type));
		parms = hash_tree_chain (integer_type_node, parms);
		newtype = build_cplus_method_type (ctx,
						   TREE_TYPE (type),
						   parms);
		newtype = build_type_variant (newtype,
					      TYPE_READONLY (type),
					      TYPE_VOLATILE (type));
		type = newtype;

		fnargs = copy_node (DECL_ARGUMENTS (t));
		TREE_CHAIN (fnargs) = TREE_CHAIN (DECL_ARGUMENTS (t));

		/* In this case we need "in-charge" flag saying whether
		   this constructor is responsible for initialization
		   of virtual baseclasses or not.  */
		parm = build_decl (PARM_DECL, in_charge_identifier, integer_type_node);
		/* Mark the artificial `__in_chrg' parameter as "artificial".  */
		SET_DECL_ARTIFICIAL (parm);
		DECL_ARG_TYPE (parm) = integer_type_node;
		DECL_REGISTER (parm) = 1;
		TREE_CHAIN (parm) = TREE_CHAIN (fnargs);
		TREE_CHAIN (fnargs) = parm;

		fnargs = tsubst (fnargs, args, nargs, t);
	      }
#if 0
	    fprintf (stderr, "\nfor function %s in class %s:\n",
		     IDENTIFIER_POINTER (name),
		     IDENTIFIER_POINTER (TYPE_IDENTIFIER (ctx)));
#endif
	    for (i = 0; i < n_methods; i++)
	      {
		int pass;

		method = TREE_VEC_ELT (methods, i);
		if (method == NULL_TREE || DECL_NAME (method) != name)
		  continue;

		pass = 0;
	      maybe_error:
		for (; method; method = DECL_CHAIN (method))
		  {
		    my_friendly_assert (TREE_CODE (method) == FUNCTION_DECL,
					282);
		    if (! comptypes (type, TREE_TYPE (method), 1))
		      {
			tree mtype = TREE_TYPE (method);
			tree t1, t2;

			/* Keep looking for a method that matches
			   perfectly.  This takes care of the problem
			   where destructors (which have implicit int args)
			   look like constructors which have an int arg.  */
			if (pass == 0)
			  continue;

			t1 = TYPE_ARG_TYPES (mtype);
			t2 = TYPE_ARG_TYPES (type);
			if (TREE_CODE (mtype) == FUNCTION_TYPE)
			  t2 = TREE_CHAIN (t2);

			if (list_eq (t1, t2))
			  {
			    if (TREE_CODE (mtype) == FUNCTION_TYPE)
			      {
				tree newtype;
				newtype = build_function_type (TREE_TYPE (type),
							       TYPE_ARG_TYPES (type));
				newtype = build_type_variant (newtype,
							      TYPE_READONLY (type),
							      TYPE_VOLATILE (type));
				type = newtype;
				if (TREE_TYPE (type) != TREE_TYPE (mtype))
				  goto maybe_bad_return_type;
			      }
			    else if (TYPE_METHOD_BASETYPE (mtype)
				     == TYPE_METHOD_BASETYPE (type))
			      {
				/* Types didn't match, but arg types and
				   `this' do match, so the return type is
				   all that should be messing it up.  */
			      maybe_bad_return_type:
				if (TREE_TYPE (type) != TREE_TYPE (mtype))
				  error ("inconsistent return types for method `%s' in class `%s'",
					 IDENTIFIER_POINTER (name),
					 IDENTIFIER_POINTER (TYPE_IDENTIFIER (ctx)));
			      }
			    r = method;
			    break;
			  }
			found = 1;
			continue;
		      }
#if 0
		    fprintf (stderr, "\tfound %s\n\n",
			     IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (method)));
#endif
		    if (DECL_ARTIFICIAL (method))
		      {
			cp_error ("template for method `%D' which has default implementation in class `%T'", name, ctx);
			if (in_decl)
			  cp_error_at ("in attempt to instantiate `%D' declared at this point in file", in_decl);
			return error_mark_node;
		      }

		    if (DECL_ARGUMENTS (method)
			&& ! TREE_PERMANENT (DECL_ARGUMENTS (method)))
		      /* @@ Is this early enough?  Might we want to do
			 this instead while processing the expansion?	 */
		      DECL_ARGUMENTS (method)
			= tsubst (DECL_ARGUMENTS (t), args, nargs, t);
		    r = method;
		    break;
		  }
		if (r == NULL_TREE && pass == 0)
		  {
		    pass = 1;
		    method = TREE_VEC_ELT (methods, i);