CppCMS/intrusive_ptr.h

#ifndef CPPCMS_INTRUSIVE_PTR_H_INCLUDED
#define CPPCMS_INTRUSIVE_PTR_H_INCLUDED

//
//  intrusive_ptr.hpp
//
//  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)
//
//  See http://www.boost.org/libs/smart_ptr/intrusive_ptr.html for documentation.
//


#include <functional>           // for std::less
#include <iosfwd>               // for std::basic_ostream


namespace cppcms
{

//
//  intrusive_ptr
//
//  A smart pointer that uses intrusive reference counting.
//
//  Relies on unqualified calls to
//  
//      void intrusive_ptr_add_ref(T * p);
//      void intrusive_ptr_release(T * p);
//
//          (p != 0)
//
//  The object is responsible for destroying itself.
//

template<class T> class intrusive_ptr
{
private:

    typedef intrusive_ptr this_type;

public:

    typedef T element_type;

    intrusive_ptr(): p_(0)
    {
    }

    intrusive_ptr(T * p, bool add_ref = true): p_(p)
    {
        if(p_ != 0 && add_ref) intrusive_ptr_add_ref(p_);
    }

    intrusive_ptr(intrusive_ptr const & rhs): p_(rhs.p_)
    {
        if(p_ != 0) intrusive_ptr_add_ref(p_);
    }

    ~intrusive_ptr()
    {
        if(p_ != 0) intrusive_ptr_release(p_);
    }

    template<class U> intrusive_ptr(intrusive_ptr<U> const & rhs): p_(rhs.get())
    {
        if(p_ != 0) intrusive_ptr_add_ref(p_);
    }

    intrusive_ptr & operator=(intrusive_ptr const & rhs)
    {
        this_type(rhs).swap(*this);
        return *this;
    }

    intrusive_ptr & operator=(T * rhs)
    {
        this_type(rhs).swap(*this);
        return *this;
    }

    T * get() const
    {
        return p_;
    }

    T & operator*() const
    {
        return *p_;
    }

    T * operator->() const
    {
        return p_;
    }


    typedef T * this_type::*unspecified_bool_type;

    operator unspecified_bool_type () const
    {
        return p_ == 0? 0: &this_type::p_;
    }

    // operator! is a Borland-specific workaround
    bool operator! () const
    {
        return p_ == 0;
    }

    void swap(intrusive_ptr & rhs)
    {
        T * tmp = p_;
        p_ = rhs.p_;
        rhs.p_ = tmp;
    }

private:

    T * p_;
};

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

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

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

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

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

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

template<class T> inline bool operator<(intrusive_ptr<T> const & a, intrusive_ptr<T> const & b)
{
    return std::less<T *>()(a.get(), b.get());
}

template<class T> void swap(intrusive_ptr<T> & lhs, intrusive_ptr<T> & rhs)
{
    lhs.swap(rhs);
}

// mem_fn support

template<class T> T * get_pointer(intrusive_ptr<T> const & p)
{
    return p.get();
}

template<class T, class U> intrusive_ptr<T> static_pointer_cast(intrusive_ptr<U> const & p)
{
    return static_cast<T *>(p.get());
}

template<class T, class U> intrusive_ptr<T> const_pointer_cast(intrusive_ptr<U> const & p)
{
    return const_cast<T *>(p.get());
}

template<class T, class U> intrusive_ptr<T> dynamic_pointer_cast(intrusive_ptr<U> const & p)
{
    return dynamic_cast<T *>(p.get());
}

// operator<<


template<class E, class T, class Y> std::basic_ostream<E, T> & operator<< (std::basic_ostream<E, T> & os, intrusive_ptr<Y> const & p)
{
    os << p.get();
    return os;
}


} // namespace cppcms

#endif  // #ifndef CPPCMS_INTRUSIVE_PTR_H_INCLUDED