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/********************* */
/*! \file cdqueue.h
** \verbatim
** Original author: bobot
** Major contributors: taking
** Minor contributors (to current version): mdeters
** This file is part of the CVC4 prototype.
** Copyright (c) 2009-2012 New York University and The University of Iowa
** See the file COPYING in the top-level source directory for licensing
** information.\endverbatim
**
** \brief Context-dependent queue class
**
** Context-dependent First-In-First-Out queue class.
** This implementation may discard elements which are enqueued and dequeued
** at the same context level.
**
** The implementation is based on a CDList with one additional size_t
** for tracking the next element to dequeue from the list and additional
** size_t for tracking the previous size of the list.
**/
#include "cvc4_private.h"
#ifndef __CVC4__CONTEXT__CDQUEUE_H
#define __CVC4__CONTEXT__CDQUEUE_H
#include "context/context.h"
#include "context/cdlist.h"
namespace CVC4 {
namespace context {
template <class T, class CleanUp = DefaultCleanUp<T>, class Allocator = std::allocator<T> >
class CDQueue;
/** We don't define a template with Allocator for the first implementation */
template <class T, class CleanUp, class Allocator>
class CDQueue : public CDList<T, CleanUp, Allocator> {
private:
typedef CDList<T, CleanUp, Allocator> ParentType;
protected:
/** Points to the next element in the current context to dequeue. */
size_t d_iter;
/** Points to the size at the last save. */
size_t d_lastsave;
/**
* Private copy constructor used only by save().
*/
CDQueue(const CDQueue<T, CleanUp, Allocator>& l):
ParentType(l),
d_iter(l.d_iter),
d_lastsave(l.d_lastsave) {}
/** Implementation of mandatory ContextObj method save:
* We assume that the base class do the job inside their copy constructor.
*/
ContextObj* save(ContextMemoryManager* pCMM) {
ContextObj* data = new(pCMM) CDQueue<T, CleanUp, Allocator>(*this);
// We save the d_size in d_lastsave and we should never destruct below this
// indices before the corresponding restore.
d_lastsave = ParentType::d_size;
Debug("cdqueue") << "save " << this
<< " at level " << this->getContext()->getLevel()
<< " size at " << this->d_size
<< " iter at " << this->d_iter
<< " lastsave at " << this->d_lastsave
<< " d_list is " << this->d_list
<< " data:" << data << std::endl;
return data;
}
/**
* Implementation of mandatory ContextObj method restore: simply
* restores the previous size, iter and lastsave indices. Note that
* the list pointer and the allocated size are not changed.
*/
void restore(ContextObj* data) {
CDQueue<T, CleanUp, Allocator>* qdata = static_cast<CDQueue<T, CleanUp, Allocator>*>(data);
d_iter = qdata->d_iter;
d_lastsave = qdata->d_lastsave;
ParentType::restore(data);
}
public:
/** Creates a new CDQueue associated with the current context. */
CDQueue(Context* context,
bool callDestructor = true,
const CleanUp& cleanup = CleanUp(),
const Allocator& alloc = Allocator())
: ParentType(context, callDestructor, cleanup, alloc),
d_iter(0),
d_lastsave(0)
{}
/** Returns true if the queue is empty in the current context. */
bool empty() const{
Assert(d_iter <= ParentType::d_size);
return d_iter == ParentType::d_size;
}
/** Returns the number of elements that have not been dequeued in the context. */
size_t size() const{
return ParentType::d_size - d_iter;
}
/** Enqueues an element in the current context. */
void push(const T& data){
ParentType::push_back(data);
}
/**
* Delete next element. The destructor of this object will be
* called eventually but not necessarily during the call of this
* function.
*/
void pop(){
Assert(!empty(), "Attempting to pop from an empty queue.");
ParentType::makeCurrent();
d_iter = d_iter + 1;
if (empty() && d_lastsave != ParentType::d_size) {
// Some elements have been enqueued and dequeued in the same
// context and now the queue is empty we can destruct them.
ParentType::truncateList(d_lastsave);
Assert(ParentType::d_size == d_lastsave);
d_iter = d_lastsave;
}
}
/** Returns a reference to the next element on the queue. */
const T& front() const{
Assert(!empty(), "No front in an empty queue.");
return ParentType::d_list[d_iter];
}
/**
* Returns the most recent item added to the queue.
*/
const T& back() const {
Assert(!empty(), "CDQueue::back() called on empty list");
return ParentType::d_list[ParentType::d_size - 1];
}
typedef typename ParentType::const_iterator const_iterator;
const_iterator begin() const {
return ParentType::begin() + d_iter;
}
const_iterator end() const {
return ParentType::end();
}
};/* class CDQueue<> */
}/* CVC4::context namespace */
}/* CVC4 namespace */
#endif /* __CVC4__CONTEXT__CDQUEUE_H */
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