scoped_array功能类似scoped_ptr，scoped_array管理的是new[]开辟的数组，其析构函数调用的是delete[]释放数组。
它没有重载解引用*和箭头操作符->，因为它不是普通指针，而是一个数组。它重载了[]，可以像使用数组下标那样访问数组。
#ifndef BOOST_SMART_PTR_SCOPED_ARRAY_HPP_INCLUDED
#define BOOST_SMART_PTR_SCOPED_ARRAY_HPP_INCLUDED
// (C) Copyright Greg Colvin and Beman Dawes 1998, 1999.
// Copyright (c) 2001, 2002 Peter Dimov
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// http://www.boost.org/libs/smart_ptr/scoped_array.htm
//
#include <boost/config.hpp>
#include <boost/assert.hpp>
#include <boost/checked_delete.hpp>
#include <boost/smart_ptr/detail/sp_nullptr_t.hpp>
#include <boost/detail/workaround.hpp>
#include <cstddef> // for std::ptrdiff_t
namespace boost
{
// Debug hooks
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
void sp_array_constructor_hook(void * p);
void sp_array_destructor_hook(void * p);
#endif
// scoped_array extends scoped_ptr to arrays. Deletion of the array pointed to
// is guaranteed, either on destruction of the scoped_array or via an explicit
// reset(). Use shared_array or std::vector if your needs are more complex.
template<class T> class scoped_array // noncopyable
{
private:
T * px;
scoped_array(scoped_array const &);
scoped_array & operator=(scoped_array const &);
typedef scoped_array<T> this_type;
void operator==( scoped_array const& ) const;
void operator!=( scoped_array const& ) const;
public:
typedef T element_type;
explicit scoped_array( T * p = 0 ) BOOST_NOEXCEPT : px( p )
{
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
boost::sp_array_constructor_hook( px );
#endif
}
~scoped_array() // never throws
{
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
boost::sp_array_destructor_hook( px );
#endif
boost::checked_array_delete( px );
}
void reset(T * p = 0) // never throws (but has a BOOST_ASSERT in it, so not marked with BOOST_NOEXCEPT)
{
BOOST_ASSERT( p == 0 || p != px ); // catch self-reset errors
this_type(p).swap(*this);
}
//重载[]，可以像访问数组一样访问其元素
T & operator[](std::ptrdiff_t i) const // never throws (but has a BOOST_ASSERT in it, so not marked with BOOST_NOEXCEPT)
{
BOOST_ASSERT( px != 0 );
BOOST_ASSERT( i >= 0 );
return px[i];
}
T * get() const BOOST_NOEXCEPT
{
return px;
}
// implicit conversion to "bool"
#include <boost/smart_ptr/detail/operator_bool.hpp>
void swap(scoped_array & b) BOOST_NOEXCEPT
{
T * tmp = b.px;
b.px = px;
px = tmp;
}
};
#if !defined( BOOST_NO_CXX11_NULLPTR )
template<class T> inline bool operator==( scoped_array<T> const & p, boost::detail::sp_nullptr_t ) BOOST_NOEXCEPT
{
return p.get() == 0;
}
template<class T> inline bool operator==( boost::detail::sp_nullptr_t, scoped_array<T> const & p ) BOOST_NOEXCEPT
{
return p.get() == 0;
}
template<class T> inline bool operator!=( scoped_array<T> const & p, boost::detail::sp_nullptr_t ) BOOST_NOEXCEPT
{
return p.get() != 0;
}
template<class T> inline bool operator!=( boost::detail::sp_nullptr_t, scoped_array<T> const & p ) BOOST_NOEXCEPT
{
return p.get() != 0;
}
#endif
template<class T> inline void swap(scoped_array<T> & a, scoped_array<T> & b) BOOST_NOEXCEPT
{
a.swap(b);
}
} // namespace boost
#endif // #ifndef BOOST_SMART_PTR_SCOPED_ARRAY_HPP_INCLUDED