/*
 *  Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2013 Apple Inc.
 *  All rights reserved.
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public License
 *  along with this library; see the file COPYING.LIB.  If not, write to
 *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *  Boston, MA 02110-1301, USA.
 *
 */

#ifndef WTF_RefPtr_h
#define WTF_RefPtr_h

#include "wtf/Allocator.h"
#include "wtf/HashTableDeletedValueType.h"
#include "wtf/PassRefPtr.h"
#include <algorithm>
#include <utility>

namespace WTF {

template <typename T>
class PassRefPtr;
template <typename T>
class RefPtrValuePeeker;

template <typename T>
class RefPtr {
  USING_FAST_MALLOC(RefPtr);

 public:
  ALWAYS_INLINE RefPtr() : m_ptr(nullptr) {}
  ALWAYS_INLINE RefPtr(std::nullptr_t) : m_ptr(nullptr) {}
  ALWAYS_INLINE RefPtr(T* ptr) : m_ptr(ptr) { refIfNotNull(ptr); }
  ALWAYS_INLINE explicit RefPtr(T& ref) : m_ptr(&ref) { m_ptr->ref(); }
  ALWAYS_INLINE RefPtr(const RefPtr& o) : m_ptr(o.m_ptr) {
    refIfNotNull(m_ptr);
  }
  template <typename U>
  RefPtr(const RefPtr<U>& o, EnsurePtrConvertibleArgDecl(U, T))
      : m_ptr(o.get()) {
    refIfNotNull(m_ptr);
  }
  RefPtr(RefPtr&& o) : m_ptr(o.m_ptr) { o.m_ptr = nullptr; }

  // See comments in PassRefPtr.h for an explanation of why this takes a const
  // reference.
  template <typename U>
  RefPtr(const PassRefPtr<U>&, EnsurePtrConvertibleArgDecl(U, T));

  // Hash table deleted values, which are only constructed and never copied or
  // destroyed.
  RefPtr(HashTableDeletedValueType) : m_ptr(hashTableDeletedValue()) {}
  bool isHashTableDeletedValue() const {
    return m_ptr == hashTableDeletedValue();
  }

  ALWAYS_INLINE ~RefPtr() { derefIfNotNull(m_ptr); }

  ALWAYS_INLINE T* get() const { return m_ptr; }

  void clear();
  PassRefPtr<T> release() {
    PassRefPtr<T> tmp = adoptRef(m_ptr);
    m_ptr = nullptr;
    return tmp;
  }

  T& operator*() const { return *m_ptr; }
  ALWAYS_INLINE T* operator->() const { return m_ptr; }

  bool operator!() const { return !m_ptr; }
  explicit operator bool() const { return m_ptr != nullptr; }

  RefPtr& operator=(RefPtr o) {
    swap(o);
    return *this;
  }
  RefPtr& operator=(std::nullptr_t) {
    clear();
    return *this;
  }
  // This is required by HashMap<RefPtr>>.
  template <typename U>
  RefPtr& operator=(RefPtrValuePeeker<U>);

  void swap(RefPtr&);

  static T* hashTableDeletedValue() { return reinterpret_cast<T*>(-1); }

 private:
  T* m_ptr;
};

template <typename T>
template <typename U>
inline RefPtr<T>::RefPtr(const PassRefPtr<U>& o,
                         EnsurePtrConvertibleArgDefn(U, T))
    : m_ptr(o.leakRef()) {}

template <typename T>
inline void RefPtr<T>::clear() {
  T* ptr = m_ptr;
  m_ptr = nullptr;
  derefIfNotNull(ptr);
}

template <typename T>
template <typename U>
inline RefPtr<T>& RefPtr<T>::operator=(RefPtrValuePeeker<U> optr) {
  RefPtr ptr = static_cast<U*>(optr);
  swap(ptr);
  return *this;
}

template <class T>
inline void RefPtr<T>::swap(RefPtr& o) {
  std::swap(m_ptr, o.m_ptr);
}

template <class T>
inline void swap(RefPtr<T>& a, RefPtr<T>& b) {
  a.swap(b);
}

template <typename T, typename U>
inline bool operator==(const RefPtr<T>& a, const RefPtr<U>& b) {
  return a.get() == b.get();
}

template <typename T, typename U>
inline bool operator==(const RefPtr<T>& a, U* b) {
  return a.get() == b;
}

template <typename T, typename U>
inline bool operator==(T* a, const RefPtr<U>& b) {
  return a == b.get();
}

template <typename T>
inline bool operator==(const RefPtr<T>& a, std::nullptr_t) {
  return !a.get();
}

template <typename T>
inline bool operator==(std::nullptr_t, const RefPtr<T>& b) {
  return !b.get();
}

template <typename T, typename U>
inline bool operator!=(const RefPtr<T>& a, const RefPtr<U>& b) {
  return a.get() != b.get();
}

template <typename T, typename U>
inline bool operator!=(const RefPtr<T>& a, U* b) {
  return a.get() != b;
}

template <typename T, typename U>
inline bool operator!=(T* a, const RefPtr<U>& b) {
  return a != b.get();
}

template <typename T>
inline bool operator!=(const RefPtr<T>& a, std::nullptr_t) {
  return a.get();
}

template <typename T>
inline bool operator!=(std::nullptr_t, const RefPtr<T>& b) {
  return b.get();
}

template <typename T>
inline T* getPtr(const RefPtr<T>& p) {
  return p.get();
}

template <typename T>
class RefPtrValuePeeker {
  DISALLOW_NEW();

 public:
  ALWAYS_INLINE RefPtrValuePeeker(T* p) : m_ptr(p) {}
  ALWAYS_INLINE RefPtrValuePeeker(std::nullptr_t) : m_ptr(nullptr) {}
  template <typename U>
  RefPtrValuePeeker(const RefPtr<U>& p) : m_ptr(p.get()) {}
  template <typename U>
  RefPtrValuePeeker(const PassRefPtr<U>& p) : m_ptr(p.get()) {}

  ALWAYS_INLINE operator T*() const { return m_ptr; }

 private:
  T* m_ptr;
};

}  // namespace WTF

using WTF::RefPtr;

#endif  // WTF_RefPtr_h