text: /*
   * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
   * Copyright (C) 2013 Intel Corporation. All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
   * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
   * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #ifndef WTF_PassOwnPtr_h
  #define WTF_PassOwnPtr_h
  
  #include "wtf/OwnPtrCommon.h"
  
  namespace WTF {
  
  template <typename T> class OwnPtr;
  template <typename T> class PassOwnPtr;
  template <typename T> PassOwnPtr<T> adoptPtr(T*);
  template <typename T> PassOwnPtr<T[]> adoptArrayPtr(T*);
  
  template <typename T> class PassOwnPtr {
  public:
      typedef typename std::remove_extent<T>::type ValueType;
      typedef ValueType* PtrType;
  
      PassOwnPtr() : m_ptr(nullptr) {}
      PassOwnPtr(std::nullptr_t) : m_ptr(nullptr) {}
  
      // It somewhat breaks the type system to allow transfer of ownership out of
      // a const PassOwnPtr. However, it makes it much easier to work with
      // PassOwnPtr temporaries, and we don't have a need to use real const
      // PassOwnPtrs anyway.
      PassOwnPtr(const PassOwnPtr& o) : m_ptr(o.leakPtr()) {}
      template <typename U> PassOwnPtr(const PassOwnPtr<U>&, EnsurePtrConvertibleArgDecl(U, T));
  
      ~PassOwnPtr() { OwnedPtrDeleter<T>::deletePtr(m_ptr); }
  
      PtrType get() const { return m_ptr; }
  
      PtrType leakPtr() const WARN_UNUSED_RETURN;
  
      ValueType& operator*() const { ASSERT(m_ptr); return *m_ptr; }
      PtrType operator->() const { ASSERT(m_ptr); return m_ptr; }
  
      bool operator!() const { return !m_ptr; }
  
      // This conversion operator allows implicit conversion to bool but not to
      // other integer types.
      typedef PtrType PassOwnPtr::*UnspecifiedBoolType;
      operator UnspecifiedBoolType() const { return m_ptr ? &PassOwnPtr::m_ptr : 0; }
  
      template <typename U> friend PassOwnPtr<U> adoptPtr(U*);
      template <typename U> friend PassOwnPtr<U[]> adoptArrayPtr(U*);
      template <typename U> friend class OwnPtr;
  
  private:
      explicit PassOwnPtr(PtrType ptr) : m_ptr(ptr) {}
  
      PassOwnPtr& operator=(const PassOwnPtr&)
      {
          static_assert(!sizeof(T*), "PassOwnPtr should never be assigned to");
          return *this;
      }
  
      // We should never have two OwnPtrs for the same underlying object
      // (otherwise we'll get double-destruction), so these equality operators
      // should never be needed.
      template <typename U> bool operator==(const PassOwnPtr<U>&) const
      {
          static_assert(!sizeof(U*), "OwnPtrs should never be equal");
          return false;
      }
      template <typename U> bool operator!=(const PassOwnPtr<U>&) const
      {
          static_assert(!sizeof(U*), "OwnPtrs should never be equal");
          return false;
      }
      template <typename U> bool operator==(const OwnPtr<U>&) const
      {
          static_assert(!sizeof(U*), "OwnPtrs should never be equal");
          return false;
      }
      template <typename U> bool operator!=(const OwnPtr<U>&) const
      {
          static_assert(!sizeof(U*), "OwnPtrs should never be equal");
          return false;
      }
  
      mutable PtrType m_ptr;
  };
  
  template <typename T>
  template <typename U> inline PassOwnPtr<T>::PassOwnPtr(const PassOwnPtr<U>& o, EnsurePtrConvertibleArgDefn(U, T))
      : m_ptr(o.leakPtr())
  {
      static_assert(!std::is_array<T>::value, "pointers to array must never be converted");
  }
  
  template <typename T> inline typename PassOwnPtr<T>::PtrType PassOwnPtr<T>::leakPtr() const
  {
      PtrType ptr = m_ptr;
      m_ptr = nullptr;
      return ptr;
  }
  
  template <typename T, typename U> inline bool operator==(const PassOwnPtr<T>& a, U* b)
  {
      return a.get() == b;
  }
  
  template <typename T, typename U> inline bool operator==(T* a, const PassOwnPtr<U>& b)
  {
      return a == b.get();
  }
  
  template <typename T, typename U> inline bool operator!=(const PassOwnPtr<T>& a, U* b)
  {
      return a.get() != b;
  }
  
  template <typename T, typename U> inline bool operator!=(T* a, const PassOwnPtr<U>& b)
  {
      return a != b.get();
  }
  
  template <typename T> inline PassOwnPtr<T> adoptPtr(T* ptr)
  {
      return PassOwnPtr<T>(ptr);
  }
  
  template <typename T> inline PassOwnPtr<T[]> adoptArrayPtr(T* ptr)
  {
      return PassOwnPtr<T[]>(ptr);
  }
  
  template <typename T, typename U> inline PassOwnPtr<T> static_pointer_cast(const PassOwnPtr<U>& p)
  {
      static_assert(!std::is_array<T>::value, "pointers to array must never be converted");
      return adoptPtr(static_cast<T*>(p.leakPtr()));
  }
  
  template <typename T> inline T* getPtr(const PassOwnPtr<T>& p)
  {
      return p.get();
  }
  
  } // namespace WTF
  
  using WTF::PassOwnPtr;
  using WTF::adoptPtr;
  using WTF::adoptArrayPtr;
  using WTF::static_pointer_cast;
  
  #endif // WTF_PassOwnPtr_h
  