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// file : cutl/shared-ptr/base.txx
// copyright : Copyright (c) 2009-2013 Code Synthesis Tools CC
// license : MIT; see accompanying LICENSE file
#include <cutl/meta/answer.hxx>
#include <cutl/meta/polymorphic-p.hxx>
namespace cutl
{
namespace bits
{
// Support for locating the counter in the memory block.
//
template <typename X, bool poly = meta::polymorphic_p<X>::r>
struct locator;
template <typename X>
struct locator<X, false>
{
static std::size_t*
counter (X* x)
{
std::size_t* p (reinterpret_cast<std::size_t*> (x));
if (*(--p) != 0xDEADBEEF)
throw not_shared ();
return --p;
}
};
template <typename X>
struct locator<X, true>
{
static std::size_t*
counter (X* x)
{
std::size_t* p (
static_cast<std::size_t*> (
dynamic_cast<void*> (x)));
if (*(--p) != 0xDEADBEEF)
throw not_shared ();
return --p;
}
};
template <typename X>
std::size_t*
counter (X const* p)
{
return bits::locator<X>::counter (const_cast<X*> (p));
}
// Counter type and operations.
//
meta::no test (...);
meta::yes test (shared_base*);
template <typename X,
std::size_t A = sizeof (bits::test (reinterpret_cast<X*> (0)))>
struct counter_type;
template <typename X>
struct counter_type<X, sizeof (meta::no)>
{
typedef X r;
};
template <typename X>
struct counter_type<X, sizeof (meta::yes)>
{
typedef shared_base r;
};
template <typename X, typename Y>
struct counter_ops;
template <typename X>
struct counter_ops<X, X>
{
counter_ops (X const* p) : counter_ (p ? bits::counter (p) : 0) {}
counter_ops (counter_ops const& x) : counter_ (x.counter_) {}
template <typename Z>
counter_ops (counter_ops<Z, Z> const& x) : counter_ (x.counter_) {}
counter_ops&
operator= (counter_ops const& x)
{
counter_ = x.counter_;
return *this;
}
template <typename Z>
counter_ops&
operator= (counter_ops<Z, Z> const& x)
{
counter_ = x.counter_;
return *this;
}
void
reset (X const* p)
{
counter_ = p ? bits::counter (p) : 0;
}
void
inc (X*)
{
(*counter_)++;
}
void
dec (X* p)
{
if (--(*counter_) == 0)
{
p->~X ();
operator delete (counter_); // Counter is the top of the memory block.
}
}
std::size_t
count (X const*) const
{
return *counter_;
}
std::size_t* counter_;
};
template <typename Y>
struct counter_ops<shared_base, Y>
{
counter_ops (Y const*) {}
counter_ops (counter_ops const&) {}
template <typename Z>
counter_ops (counter_ops<shared_base, Z> const&) {}
counter_ops&
operator= (counter_ops const&)
{
return *this;
}
template <typename Z>
counter_ops&
operator= (counter_ops<shared_base, Z> const&)
{
return *this;
}
void
reset (Y const*) {}
void
inc (shared_base* p) {p->_inc_ref ();}
void
dec (Y* p)
{
if (static_cast<shared_base*> (p)->_dec_ref ())
delete p;
}
std::size_t
count (shared_base const* p) const {return p->_ref_count ();}
};
}
template <typename X>
inline X*
inc_ref (X* p)
{
bits::counter_ops<typename bits::counter_type<X>::r, X> c (p);
c.inc (p);
return p;
}
template <typename X>
inline void
dec_ref (X* p)
{
bits::counter_ops<typename bits::counter_type<X>::r, X> c (p);
c.dec (p);
}
template <typename X>
inline std::size_t
ref_count (X const* p)
{
bits::counter_ops<typename bits::counter_type<X>::r, X> c (p);
return c.count (p);
}
}
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