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/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
/*
* Main authors:
* Christian Schulte <schulte@gecode.org>
*
* Copyright:
* Christian Schulte, 2017
*
* This file is part of Gecode, the generic constraint
* development environment:
* http://www.gecode.org
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
namespace Gecode {
/**
* \brief The shared handle
*
* A shared handle provides access to an object that lives outside a space,
* and is shared between entities that possibly reside inside different
* spaces.
*
* This is the base class that all shared handles must inherit from.
*
*/
class SharedHandle {
public:
/**
* \brief The shared object
*
* Shared objects must inherit from this base class.
*/
class GECODE_KERNEL_EXPORT Object : public HeapAllocated {
friend class SharedHandle;
private:
/// The counter used for reference counting
Support::RefCount rc;
public:
/// Initialize
Object(void);
/// Delete shared object
virtual ~Object(void);
};
private:
/// The shared object
Object* o;
/// Subscribe handle to object
void subscribe(void);
/// Cancel subscription of handle to object
void cancel(void);
public:
/// Create shared handle with no object pointing to
SharedHandle(void);
/// Create shared handle that points to shared object \a so
SharedHandle(SharedHandle::Object* so);
/// Copy constructor maintaining reference count
SharedHandle(const SharedHandle& sh);
/// Assignment operator maintaining reference count
SharedHandle& operator =(const SharedHandle& sh);
/// Destructor that maintains reference count
~SharedHandle(void);
/// Whether handle points to an object
explicit operator bool(void) const;
protected:
/// Access to the shared object
SharedHandle::Object* object(void) const;
/// Modify shared object
void object(SharedHandle::Object* n);
};
forceinline
SharedHandle::Object::Object(void)
: rc(0) {}
forceinline
SharedHandle::Object::~Object(void) {
assert(!rc);
}
forceinline SharedHandle::Object*
SharedHandle::object(void) const {
return o;
}
forceinline void
SharedHandle::subscribe(void) {
if (o != nullptr) o->rc.inc();
}
forceinline void
SharedHandle::cancel(void) {
if ((o != nullptr) && o->rc.dec())
delete o;
o=nullptr;
}
forceinline void
SharedHandle::object(SharedHandle::Object* n) {
if (n != o) {
cancel(); o=n; subscribe();
}
}
forceinline
SharedHandle::SharedHandle(void) : o(nullptr) {}
forceinline
SharedHandle::SharedHandle(SharedHandle::Object* so) : o(so) {
subscribe();
}
forceinline
SharedHandle::SharedHandle(const SharedHandle& sh) : o(sh.o) {
subscribe();
}
forceinline SharedHandle&
SharedHandle::operator =(const SharedHandle& sh) {
if (&sh != this) {
cancel(); o=sh.o; subscribe();
}
return *this;
}
forceinline
SharedHandle::operator bool(void) const {
return o != nullptr;
}
forceinline
SharedHandle::~SharedHandle(void) {
cancel();
}
}
// STATISTICS: kernel-memory
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