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Boost源码学习---
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
Boost源码学习---
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