orderedEliminationSequenceStrategy.cpp

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 *       - Pierre-Henri WUILLEMIN(_at_LIP6)                                 *
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#include <agrum/agrum.h>
 
#include <agrum/base/graphs/algorithms/triangulations/eliminationStrategies/orderedEliminationSequenceStrategy.h>
 
#ifdef GUM_NO_INLINE
#  include <agrum/base/graphs/algorithms/triangulations/eliminationStrategies/orderedEliminationSequenceStrategy_inl.h>
#endif   // GU%_NO_INLINE
 
namespace gum {

  OrderedEliminationSequenceStrategy::OrderedEliminationSequenceStrategy() {
    GUM_CONSTRUCTOR(OrderedEliminationSequenceStrategy);
  }

  OrderedEliminationSequenceStrategy::OrderedEliminationSequenceStrategy(
      UndiGraph*                   graph,
      const NodeProperty< Size >*  dom_sizes,
      const std::vector< NodeId >* order) : EliminationSequenceStrategy(graph, dom_sizes) {
    // check that the user passed appropriate graphs and orders
    if (((graph == nullptr) && (order != nullptr)) || ((graph != nullptr) && (order == nullptr))) {
      GUM_ERROR(GraphError,
                "OrderedEliminationSequenceStrategy needs either both nullptrs "
                "or both non-nullptrs on graph and elimination ordering");
    }
 
    setOrder(order);
 
    GUM_CONSTRUCTOR(OrderedEliminationSequenceStrategy);
  }

  OrderedEliminationSequenceStrategy::OrderedEliminationSequenceStrategy(
      const OrderedEliminationSequenceStrategy& from) :
      EliminationSequenceStrategy(from), _order_(from._order_), _order_index_(from._order_index_),
      _order_needed_(from._order_needed_) {
    GUM_CONS_CPY(OrderedEliminationSequenceStrategy);
  }

  OrderedEliminationSequenceStrategy::OrderedEliminationSequenceStrategy(
      OrderedEliminationSequenceStrategy&& from) :
      EliminationSequenceStrategy(std::move(from)), _order_(from._order_),
      _order_index_(from._order_index_), _order_needed_(from._order_needed_) {
    GUM_CONS_MOV(OrderedEliminationSequenceStrategy);
  }

  OrderedEliminationSequenceStrategy::~OrderedEliminationSequenceStrategy() {
    GUM_DESTRUCTOR(OrderedEliminationSequenceStrategy);
  }

  OrderedEliminationSequenceStrategy* OrderedEliminationSequenceStrategy::newFactory() const {
    return new OrderedEliminationSequenceStrategy();
  }

  OrderedEliminationSequenceStrategy* OrderedEliminationSequenceStrategy::copyFactory() const {
    return new OrderedEliminationSequenceStrategy(*this);
  }

  bool OrderedEliminationSequenceStrategy::setGraph(UndiGraph*                  graph,
                                                    const NodeProperty< Size >* domain_sizes) {
    if (EliminationSequenceStrategy::setGraph(graph, domain_sizes)) {
      setOrder(_order_);
      return true;
    }
 
    return false;
  }

  bool OrderedEliminationSequenceStrategy::_isOrderNeeded_(
      const std::vector< NodeId >* order) const {
    if ((graph_ == nullptr) || (order == nullptr)) return true;
 
    // determine the set of nodes in the order that belong to the graph
    NodeSet nodes_found(graph_->size() / 2);
    for (const auto node: *order) {
      if (graph_->existsNode(node)) { nodes_found.insert(node); }
    }
 
    // check that the size of nodes_found is equal to that of the graph
    return nodes_found.size() != graph_->size();
  }

  bool OrderedEliminationSequenceStrategy::setOrder(const std::vector< NodeId >* order) {
    // check that the order contains all the nodes of the graph
    _order_needed_ = _isOrderNeeded_(order);
 
    if (!_order_needed_) {
      _order_ = order;
 
      // determine the first element in order that belong to the graph
      // here, note that we have the guarantee that  _order_index_ will be
      // lower than the size of  _order_ since all the nodes in the graph
      // belong to vector  _order_
      _order_index_ = 0;
      while (!graph_->existsNode((*_order_)[_order_index_]))
        ++_order_index_;
 
      return true;
    }
 
    return false;
  }

  void OrderedEliminationSequenceStrategy::clear() {
    EliminationSequenceStrategy::clear();
    _order_needed_ = true;
    _order_index_  = std::size_t(0);
  }

  NodeId OrderedEliminationSequenceStrategy::nextNodeToEliminate() {
    // check that we can return a nodeId
    if (_order_needed_ || (_order_->size() <= _order_index_)) {
      GUM_ERROR(NotFound, "no node id can be returned")
    }
 
    return (*_order_)[_order_index_];
  }

  void OrderedEliminationSequenceStrategy::askFillIns(bool do_it) {
    // do nothing: we are not able to compute fill-ins
  }

  bool OrderedEliminationSequenceStrategy::providesFillIns() const { return false; }

  bool OrderedEliminationSequenceStrategy::providesGraphUpdate() const { return false; }

  void OrderedEliminationSequenceStrategy::eliminationUpdate(const NodeId node) {
    // check whether there is something to update
    if (!_order_needed_) {
      // check that node corresponds to the current index
      if ((_order_index_ >= _order_->size()) || ((*_order_)[_order_index_] != node)) {
        GUM_ERROR(OutOfBounds,
                  "update impossible because node "
                      << node << " does not correspond to the current elimination index");
      }
 
      // now perform the update: goto the next node that belongs to graph_
      ++_order_index_;
      std::size_t size = _order_->size();
      while ((_order_index_ < size) && !graph_->existsNode((*_order_)[_order_index_]))
        ++_order_index_;
    }
  }

  const EdgeSet& OrderedEliminationSequenceStrategy::fillIns() {
    return EliminationSequenceStrategy::fillIns();
  }
 
} /* namespace gum */