/*
 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#ifndef SHARE_VM_UTILITIES_TRAITS_IS_BASE_OF_HPP
#define SHARE_VM_UTILITIES_TRAITS_IS_BASE_OF_HPP

#include "utilities/traits/isClassOrUnion.hpp"
#include "utilities/traits/isSame.hpp"
#include "utilities/traits/removeCv.hpp"

/**
 * IsBaseOfAndDerived<Base, Derived>::value is true if Derived is a derived class of Base, disgarding their CV qualifiers.
 * Returns false for non-class types.
 */
template<typename Base, typename Derived>
class IsBaseOfAndDerived {
  typedef char yes[1];
  typedef char no[2];

  template<typename T>
  static yes &check(Derived*, T);
  static no &check(Base*, int);

  template<typename B, typename D>
  struct IsBaseOfHost {
    operator B*() const;
    operator D*();
  };

  template<typename B, typename D>
  struct IsBaseOfAndDerivedInternal {
    static const bool value = sizeof(check(IsBaseOfHost<B, D>(), int())) == sizeof(yes);
  };

public:
  static const bool value = IsClassOrUnion<Base>::value &&
      IsBaseOfAndDerivedInternal<typename RemoveCv<Base>::type, typename RemoveCv<Derived>::type>::value &&
      !IsSame<typename RemoveCv<Base>::type, typename RemoveCv<Derived>::type>::value;
};

/**
 * IsBaseOf<Base, Derived>::value is true if either Derived is a derived class of Base 
 * disregarding CV qualifiers or Derived and Base are the same type disregarding CV qualifiers.
 * Returns false for all non-class types. 
 * Note: It can currently return true for unions, but that behaviour
 * is subject to change when compiler compatibility for detecting unions is better, and hence
 * that behaviour should not be relied upon.
 */
template<typename Base, typename Derived>
class IsBaseOf {
public:
  static const bool value = (IsBaseOfAndDerived<Base, Derived>::value ||
      IsSame<typename RemoveCv<Base>::type, typename RemoveCv<Derived>::type>::value) && 
      IsClassOrUnion<Base>::value;
};

#endif // SHARE_VM_UTILITIES_TRAITS_IS_BASE_OF_HPP