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tdegraphics/ksvg/impl/libs/libtext2path/src/myboost/shared_count.h

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7.6 KiB

#ifndef BOOST_DETAIL_SHARED_COUNT_H_INCLUDED
#define BOOST_DETAIL_SHARED_COUNT_H_INCLUDED
//
// detail/shared_count.h
//
// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
//
// Permission to copy, use, modify, sell and distribute this software
// is granted provided this copyright notice appears in all copies.
// This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
//
#include "myboost/checked_delete.h"
#include "myboost/throw_exception.h"
#include "myboost/lightweight_mutex.h"
#include <memory> // std::auto_ptr, std::allocator
#include <functional> // std::less
#include <exception> // std::exception
#include <new> // std::bad_alloc
#include <typeinfo> // std::type_info in get_deleter
#include <cstddef> // std::size_t
namespace myboost
{
class bad_weak_ptr: public std::exception
{
public:
virtual char const * what() const throw()
{
return "myboost::bad_weak_ptr";
}
};
namespace detail
{
class sp_counted_base
{
private:
typedef detail::lightweight_mutex mutex_type;
public:
sp_counted_base(): use_count_(1), weak_count_(1)
{
}
virtual ~sp_counted_base() // nothrow
{
}
// dispose() is called when use_count_ drops to zero, to release
// the resources managed by *this.
virtual void dispose() = 0; // nothrow
// destruct() is called when weak_count_ drops to zero.
virtual void destruct() // nothrow
{
delete this;
}
virtual void * get_deleter(std::type_info const & ti) = 0;
void add_ref_copy()
{
mutex_type::scoped_lock lock(mtx_);
++use_count_;
}
void add_ref_lock()
{
mutex_type::scoped_lock lock(mtx_);
if(use_count_ == 0) myboost::throw_exception(myboost::bad_weak_ptr());
++use_count_;
}
void release() // nothrow
{
{
mutex_type::scoped_lock lock(mtx_);
long new_use_count = --use_count_;
if(new_use_count != 0) return;
}
dispose();
weak_release();
}
void weak_add_ref() // nothrow
{
mutex_type::scoped_lock lock(mtx_);
++weak_count_;
}
void weak_release() // nothrow
{
long new_weak_count;
{
mutex_type::scoped_lock lock(mtx_);
new_weak_count = --weak_count_;
}
if(new_weak_count == 0)
{
destruct();
}
}
long use_count() const // nothrow
{
mutex_type::scoped_lock lock(mtx_);
return use_count_;
}
private:
sp_counted_base(sp_counted_base const &);
sp_counted_base & operator= (sp_counted_base const &);
long use_count_; // #shared
long weak_count_; // #weak + (#shared != 0)
mutable mutex_type mtx_;
};
template<class P, class D> class sp_counted_base_impl: public sp_counted_base
{
private:
P ptr; // copy constructor must not throw
D del; // copy constructor must not throw
sp_counted_base_impl(sp_counted_base_impl const &);
sp_counted_base_impl & operator= (sp_counted_base_impl const &);
typedef sp_counted_base_impl<P, D> this_type;
public:
// pre: initial_use_count <= initial_weak_count, d(p) must not throw
sp_counted_base_impl(P p, D d): ptr(p), del(d)
{
}
virtual void dispose() // nothrow
{
del(ptr);
}
virtual void * get_deleter(std::type_info const & ti)
{
return ti == typeid(D)? &del: 0;
}
void * operator new(std::size_t)
{
return std::allocator<this_type>().allocate(1, static_cast<this_type *>(0));
}
void operator delete(void * p)
{
std::allocator<this_type>().deallocate(static_cast<this_type *>(p), 1);
}
};
class weak_count;
class shared_count
{
private:
sp_counted_base * pi_;
friend class weak_count;
public:
shared_count(): pi_(0) // nothrow
{
}
template<class P, class D> shared_count(P p, D d): pi_(0)
{
try
{
pi_ = new sp_counted_base_impl<P, D>(p, d);
}
catch(...)
{
d(p); // delete p
throw;
}
pi_ = new sp_counted_base_impl<P, D>(p, d);
if(pi_ == 0)
{
d(p); // delete p
myboost::throw_exception(std::bad_alloc());
}
}
// auto_ptr<Y> is special cased to provide the strong guarantee
template<class Y>
explicit shared_count(std::auto_ptr<Y> & r): pi_(new sp_counted_base_impl< Y *, checked_deleter<Y> >(r.get(), checked_deleter<Y>()))
{
r.release();
}
~shared_count() // nothrow
{
if(pi_ != 0) pi_->release();
}
shared_count(shared_count const & r): pi_(r.pi_) // nothrow
{
if(pi_ != 0) pi_->add_ref_copy();
}
explicit shared_count(weak_count const & r); // throws bad_weak_ptr when r.use_count() == 0
shared_count & operator= (shared_count const & r) // nothrow
{
sp_counted_base * tmp = r.pi_;
if(tmp != 0) tmp->add_ref_copy();
if(pi_ != 0) pi_->release();
pi_ = tmp;
return *this;
}
void swap(shared_count & r) // nothrow
{
sp_counted_base * tmp = r.pi_;
r.pi_ = pi_;
pi_ = tmp;
}
long use_count() const // nothrow
{
return pi_ != 0? pi_->use_count(): 0;
}
bool unique() const // nothrow
{
return use_count() == 1;
}
friend inline bool operator==(shared_count const & a, shared_count const & b)
{
return a.pi_ == b.pi_;
}
friend inline bool operator<(shared_count const & a, shared_count const & b)
{
return std::less<sp_counted_base *>()(a.pi_, b.pi_);
}
void * get_deleter(std::type_info const & ti) const
{
return pi_? pi_->get_deleter(ti): 0;
}
};
class weak_count
{
private:
sp_counted_base * pi_;
friend class shared_count;
public:
weak_count(): pi_(0) // nothrow
{
}
weak_count(shared_count const & r): pi_(r.pi_) // nothrow
{
if(pi_ != 0) pi_->weak_add_ref();
}
weak_count(weak_count const & r): pi_(r.pi_) // nothrow
{
if(pi_ != 0) pi_->weak_add_ref();
}
~weak_count() // nothrow
{
if(pi_ != 0) pi_->weak_release();
}
weak_count & operator= (shared_count const & r) // nothrow
{
sp_counted_base * tmp = r.pi_;
if(tmp != 0) tmp->weak_add_ref();
if(pi_ != 0) pi_->weak_release();
pi_ = tmp;
return *this;
}
weak_count & operator= (weak_count const & r) // nothrow
{
sp_counted_base * tmp = r.pi_;
if(tmp != 0) tmp->weak_add_ref();
if(pi_ != 0) pi_->weak_release();
pi_ = tmp;
return *this;
}
void swap(weak_count & r) // nothrow
{
sp_counted_base * tmp = r.pi_;
r.pi_ = pi_;
pi_ = tmp;
}
long use_count() const // nothrow
{
return pi_ != 0? pi_->use_count(): 0;
}
friend inline bool operator==(weak_count const & a, weak_count const & b)
{
return a.pi_ == b.pi_;
}
friend inline bool operator<(weak_count const & a, weak_count const & b)
{
return std::less<sp_counted_base *>()(a.pi_, b.pi_);
}
};
inline shared_count::shared_count(weak_count const & r): pi_(r.pi_)
{
if(pi_ != 0)
{
pi_->add_ref_lock();
}
else
{
myboost::throw_exception(myboost::bad_weak_ptr());
}
}
} // namespace detail
} // namespace myboost
#endif // #ifndef BOOST_DETAIL_SHARED_COUNT_H_INCLUDED