unique_ptr.h

// unique_ptr implementation -*- C++ -*-

// Copyright (C) 2008, 2009 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, 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 General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file unique_ptr.h
 *  This is an internal header file, included by other library headers.
 *  You should not attempt to use it directly.
 */

#ifndef _UNIQUE_PTR_H
#define _UNIQUE_PTR_H 1

#ifndef __GXX_EXPERIMENTAL_CXX0X__
#include <c++0x_warning.h>
#endif

#include <bits/c++config.h>
#include <debug/debug.h>
#include <type_traits>
#include <utility>
#include <tuple>

_GLIBCXX_BEGIN_NAMESPACE(std)

/**
 * @addtogroup pointer_abstractions
 * @{
 */

/// Primary template, default_delete.
template <typename _Tp>
struct default_delete
{
  default_delete() {}

  template <typename _Up>
  default_delete(const default_delete<_Up> &) {}

  void operator()(_Tp *__ptr) const
  {
    static_assert(sizeof(_Tp) > 0, "can't delete pointer to incomplete type");
    delete __ptr;
  }
};

// _GLIBCXX_RESOLVE_LIB_DEFECTS
// DR 740 - omit specialization for array objects with a compile time length
/// Specialization, default_delete.
template <typename _Tp>
struct default_delete<_Tp[]>
{
  void operator()(_Tp *__ptr) const
  {
    static_assert(sizeof(_Tp) > 0, "can't delete pointer to incomplete type");
    delete[] __ptr;
  }
};

/// 20.7.12.2 unique_ptr for single objects.
template <typename _Tp, typename _Tp_Deleter = default_delete<_Tp>>
class unique_ptr
{
  typedef std::tuple<_Tp *, _Tp_Deleter> __tuple_type; // 使用元组存放pointer和deleter
  typedef __tuple_type unique_ptr::*__unspecified_bool_type;
  typedef _Tp *unique_ptr::*__unspecified_pointer_type;

public:
  typedef _Tp *pointer;
  typedef _Tp element_type;
  typedef _Tp_Deleter deleter_type;

  // Constructors.
  unique_ptr() : _M_t(pointer(), deleter_type())
  {
    static_assert(!std::is_pointer<deleter_type>::value, "constructed with null function pointer deleter");
  }

  explicit unique_ptr(pointer __p) : _M_t(__p, deleter_type())
  {
    static_assert(!std::is_pointer<deleter_type>::value, "constructed with null function pointer deleter");
  }

  unique_ptr(pointer __p, typename std::conditional<std::is_reference<deleter_type>::value, deleter_type, const deleter_type &>::type __d) : _M_t(__p, __d)
  {
  }

  unique_ptr(pointer __p, typename std::remove_reference<deleter_type>::type &&__d) : _M_t(std::move(__p), std::move(__d))
  {
    static_assert(!std::is_reference<deleter_type>::value, "rvalue deleter bound to reference");
  }

  // 移动构造
  // Move constructors.
  unique_ptr(unique_ptr &&__u) : _M_t(__u.release(), std::forward<deleter_type>(__u.get_deleter()))
  {
  }

  template <typename _Up, typename _Up_Deleter>
  unique_ptr(unique_ptr<_Up, _Up_Deleter> &&__u) : _M_t(__u.release(), std::forward<deleter_type>(__u.get_deleter()))
  {
  }

  // Destructor.
  ~unique_ptr() { reset(); }

  // 移动赋值
  //  Assignment.
  unique_ptr &operator=(unique_ptr &&__u)
  {
    // 重置指针为__u的指针
    reset(__u.release());
    // 修改deleter
    get_deleter() = std::move(__u.get_deleter());
    return *this;
  }

  template <typename _Up, typename _Up_Deleter>
  unique_ptr &operator=(unique_ptr<_Up, _Up_Deleter> &&__u)
  {
    reset(__u.release());
    get_deleter() = std::move(__u.get_deleter());
    return *this;
  }

  unique_ptr &operator=(__unspecified_pointer_type)
  {
    reset();
    return *this;
  }

  // Observers.
  typename std::add_lvalue_reference<element_type>::type operator*() const
  {
    _GLIBCXX_DEBUG_ASSERT(get() != 0);
    return *get();
  }

  pointer operator->() const
  {
    _GLIBCXX_DEBUG_ASSERT(get() != 0);
    return get();
  }

  // 从元组中提取pointer
  pointer get() const
  {
    return std::get<0>(_M_t);
  }

  // 从元组中提取deleter
  typename std::add_lvalue_reference<deleter_type>::type get_deleter()
  {
    return std::get<1>(_M_t);
  }

  typename std::add_lvalue_reference<typename std::add_const<deleter_type>::type>::type get_deleter() const
  {
    return std::get<1>(_M_t);
  }

  operator __unspecified_bool_type() const
  {
    return get() == 0 ? 0 : &unique_ptr::_M_t;
  }

  // 释放指针资源
  //  Modifiers.
  pointer release()
  {
    pointer __p = get();
    std::get<0>(_M_t) = 0;
    return __p;
  }

  // 重置
  void reset(pointer __p = pointer())
  {
    if (__p != get())
    {
      // 删除资源
      get_deleter()(get());
      // 重新赋值指针
      std::get<0>(_M_t) = __p;
    }
  }

  // 交换
  void swap(unique_ptr &&__u)
  {
    using std::swap;
    // 交换内部元组结构
    swap(_M_t, __u._M_t);
  }

  // 禁用左值拷贝
  //  Disable copy from lvalue.
  unique_ptr(const unique_ptr &) = delete;

  template <typename _Up, typename _Up_Deleter>
  unique_ptr(const unique_ptr<_Up, _Up_Deleter> &) = delete;

  unique_ptr &operator=(const unique_ptr &) = delete;

  template <typename _Up, typename _Up_Deleter>
  unique_ptr &operator=(const unique_ptr<_Up, _Up_Deleter> &) = delete;

private:
  __tuple_type _M_t; // pointer+deleter
};

/// 20.7.12.3 unique_ptr for array objects with a runtime length
// [unique.ptr.runtime]
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// DR 740 - omit specialization for array objects with a compile time length
template <typename _Tp, typename _Tp_Deleter>
class unique_ptr<_Tp[], _Tp_Deleter>
{
  typedef std::tuple<_Tp *, _Tp_Deleter> __tuple_type;
  typedef __tuple_type unique_ptr::*__unspecified_bool_type;
  typedef _Tp *unique_ptr::*__unspecified_pointer_type;

public:
  typedef _Tp *pointer;
  typedef _Tp element_type;
  typedef _Tp_Deleter deleter_type;

  // Constructors.
  unique_ptr() : _M_t(pointer(), deleter_type())
  {
    static_assert(!std::is_pointer<deleter_type>::value, "constructed with null function pointer deleter");
  }

  explicit unique_ptr(pointer __p) : _M_t(__p, deleter_type())
  {
    static_assert(!std::is_pointer<deleter_type>::value, "constructed with null function pointer deleter");
  }

  unique_ptr(pointer __p, typename std::conditional<std::is_reference<deleter_type>::value, deleter_type, const deleter_type &>::type __d) : _M_t(__p, __d) {}

  unique_ptr(pointer __p, typename std::remove_reference<deleter_type>::type &&__d) : _M_t(std::move(__p), std::move(__d))
  {
    static_assert(!std::is_reference<deleter_type>::value, "rvalue deleter bound to reference");
  }

  // Move constructors.
  unique_ptr(unique_ptr &&__u) : _M_t(__u.release(), std::forward<deleter_type>(__u.get_deleter())) {}

  template <typename _Up, typename _Up_Deleter>
  unique_ptr(unique_ptr<_Up, _Up_Deleter> &&__u) : _M_t(__u.release(), std::forward<deleter_type>(__u.get_deleter()))
  {
  }

  // Destructor.
  ~unique_ptr() { reset(); }

  // Assignment.
  unique_ptr &operator=(unique_ptr &&__u)
  {
    reset(__u.release());
    get_deleter() = std::move(__u.get_deleter());
    return *this;
  }

  template <typename _Up, typename _Up_Deleter>
  unique_ptr &operator=(unique_ptr<_Up, _Up_Deleter> &&__u)
  {
    reset(__u.release());
    get_deleter() = std::move(__u.get_deleter());
    return *this;
  }

  unique_ptr &operator=(__unspecified_pointer_type)
  {
    reset();
    return *this;
  }

  // Observers.
  typename std::add_lvalue_reference<element_type>::type operator[](size_t __i) const
  {
    _GLIBCXX_DEBUG_ASSERT(get() != 0);
    return get()[__i];
  }

  pointer get() const
  {
    return std::get<0>(_M_t);
  }

  typename std::add_lvalue_reference<deleter_type>::type get_deleter()
  {
    return std::get<1>(_M_t);
  }

  typename std::add_lvalue_reference<typename std::add_const<deleter_type>::type>::type get_deleter() const
  {
    return std::get<1>(_M_t);
  }

  operator __unspecified_bool_type() const
  {
    return get() == 0 ? 0 : &unique_ptr::_M_t;
  }

  // Modifiers.
  pointer release()
  {
    pointer __p = get();
    std::get<0>(_M_t) = 0;
    return __p;
  }

  void reset(pointer __p = pointer())
  {
    if (__p != get())
    {
      get_deleter()(get());
      std::get<0>(_M_t) = __p;
    }
  }

  // DR 821.
  template <typename _Up>
  void reset(_Up) = delete;

  void swap(unique_ptr &&__u)
  {
    using std::swap;
    swap(_M_t, __u._M_t);
  }

  // Disable copy from lvalue.
  unique_ptr(const unique_ptr &) = delete;
  unique_ptr &operator=(const unique_ptr &) = delete;

  // Disable construction from convertible pointer types.
  // (N2315 - 20.6.5.3.1)
  template <typename _Up>
  unique_ptr(_Up *, typename std::conditional<std::is_reference<deleter_type>::value, deleter_type, const deleter_type &>::type, typename std::enable_if<std::is_convertible<_Up *, pointer>::value>::type * = 0) = delete;

  template <typename _Up>
  unique_ptr(_Up *, typename std::remove_reference<deleter_type>::type &&, typename std::enable_if<std::is_convertible<_Up *, pointer>::value>::type * = 0) = delete;

  template <typename _Up>
  explicit unique_ptr(_Up *, typename std::enable_if<std::is_convertible<_Up *, pointer>::value>::type * = 0) = delete;

private:
  __tuple_type _M_t;
};

template <typename _Tp, typename _Tp_Deleter>
inline void
swap(unique_ptr<_Tp, _Tp_Deleter> &__x, unique_ptr<_Tp, _Tp_Deleter> &__y)
{
  __x.swap(__y);
}

template <typename _Tp, typename _Tp_Deleter>
inline void swap(unique_ptr<_Tp, _Tp_Deleter> &&__x, unique_ptr<_Tp, _Tp_Deleter> &__y)
{
  __x.swap(__y);
}

template <typename _Tp, typename _Tp_Deleter>
inline void swap(unique_ptr<_Tp, _Tp_Deleter> &__x, unique_ptr<_Tp, _Tp_Deleter> &&__y)
{
  __x.swap(__y);
}

template <typename _Tp, typename _Tp_Deleter, typename _Up, typename _Up_Deleter>
inline bool operator==(const unique_ptr<_Tp, _Tp_Deleter> &__x, const unique_ptr<_Up, _Up_Deleter> &__y)
{
  return __x.get() == __y.get();
}

template <typename _Tp, typename _Tp_Deleter, typename _Up, typename _Up_Deleter>
inline bool operator!=(const unique_ptr<_Tp, _Tp_Deleter> &__x, const unique_ptr<_Up, _Up_Deleter> &__y)
{
  return !(__x.get() == __y.get());
}

template <typename _Tp, typename _Tp_Deleter, typename _Up, typename _Up_Deleter>
inline bool operator<(const unique_ptr<_Tp, _Tp_Deleter> &__x, const unique_ptr<_Up, _Up_Deleter> &__y)
{
  return __x.get() < __y.get();
}

template <typename _Tp, typename _Tp_Deleter, typename _Up, typename _Up_Deleter>
inline bool operator<=(const unique_ptr<_Tp, _Tp_Deleter> &__x, const unique_ptr<_Up, _Up_Deleter> &__y)
{
  return !(__y.get() < __x.get());
}

template <typename _Tp, typename _Tp_Deleter, typename _Up, typename _Up_Deleter>
inline bool operator>(const unique_ptr<_Tp, _Tp_Deleter> &__x, const unique_ptr<_Up, _Up_Deleter> &__y)
{
  return __y.get() < __x.get();
}

template <typename _Tp, typename _Tp_Deleter, typename _Up, typename _Up_Deleter>
inline bool operator>=(const unique_ptr<_Tp, _Tp_Deleter> &__x, const unique_ptr<_Up, _Up_Deleter> &__y)
{
  return !(__x.get() < __y.get());
}

// @} group pointer_abstractions

_GLIBCXX_END_NAMESPACE

#endif /* _UNIQUE_PTR_H */