CompositeImpliesNode.cpp

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/* -*- C++ -*- */

#ifndef _COMPOSITE_IMPLIES_NODE_CPP
#define _COMPOSITE_IMPLIES_NODE_CPP

#ifndef _MADARA_NO_KARL_

#include <iostream>

#include "madara/expression/ComponentNode.h"
#include "madara/expression/Visitor.h"
#include "madara/expression/CompositeImpliesNode.h"
#include "madara/expression/LeafNode.h"


// Ctor

madara::expression::CompositeImpliesNode::CompositeImpliesNode (
  logger::Logger & logger,
  ComponentNode *left, ComponentNode *right)
: madara::expression::CompositeBinaryNode (logger, left, right)
{    
}

madara::knowledge::KnowledgeRecord
madara::expression::CompositeImpliesNode::item (void) const
{
  madara::knowledge::KnowledgeRecord record;
  record.set_value ("=>");
  return record;
}


madara::knowledge::KnowledgeRecord
madara::expression::CompositeImpliesNode::prune (bool & can_change)
{
  bool left_child_can_change = false;
  bool right_child_can_change = false;
  madara::knowledge::KnowledgeRecord left_value;
  madara::knowledge::KnowledgeRecord right_value;

  if (this->left_)
  {
    left_value = this->left_->prune (left_child_can_change);
    if (!left_child_can_change && dynamic_cast <LeafNode *> (left_) == 0)
    {
      delete this->left_;
      this->left_ = new LeafNode (*(this->logger_), left_value);
    }
  }
  else
  {
    madara_logger_ptr_log (logger_, logger::LOG_ERROR,
      "madara::expression::CompositeImpliesNode: "
      "KARL COMPILE ERROR: Implies has no condition\n");

    throw KarlException ("madara::expression::CompositeImpliesNode: "
      "KARL COMPILE ERROR: "
      "Implies has no condition (left) expression\n"); 
  }

  if (this->right_)
  {
    right_value = this->right_->prune (right_child_can_change);
    if (!right_child_can_change && dynamic_cast <LeafNode *> (right_) == 0)
    {
      delete this->right_;
      this->right_ = new LeafNode (*(this->logger_), right_value);
    }
  }
  else
  {
    madara_logger_ptr_log (logger_, logger::LOG_ERROR,
      "madara::expression::CompositeImpliesNode: "
      "KARL COMPILE ERROR: Implies has no expression to "
      "evaluate if conditional is true\n");

    throw KarlException ("madara::expression::CompositeImpliesNode: "
      "KARL COMPILE ERROR: "
      "Implies has no right expression\n"); 
  }

  can_change = left_child_can_change || right_child_can_change;

  // if left_value, then return the right_value. Otherwise, 0
  return left_value;
}

madara::knowledge::KnowledgeRecord 
madara::expression::CompositeImpliesNode::evaluate (
  const madara::knowledge::KnowledgeUpdateSettings & settings)
{
  madara::knowledge::KnowledgeRecord left_value = left_->evaluate (settings);

  // only evaluate right if left evaluates to non-zero
  if (left_value.is_true ())
    right_->evaluate (settings);

  return left_value;
}


// accept a visitor
void 
madara::expression::CompositeImpliesNode::accept (Visitor &visitor) const
{
  visitor.visit (*this);
}

#endif // _MADARA_NO_KARL_

#endif /* _COMPOSITE_IMPLIES_NODE_CPP */