EqualsPredicateIndex.h

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/*
 Copyright (2016) Michael Baer, Daniel Bonrath, All rights reserved.

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

#ifndef __M2ETIS_PUBSUB_FILTER_GENERALBOOLEANALGEBRA_EQUALSPREDICATEINDEX_H__
#define __M2ETIS_PUBSUB_FILTER_GENERALBOOLEANALGEBRA_EQUALSPREDICATEINDEX_H__

#include "m2etis/pubsub/filter/filterexpressions/EqualsAttributeFilter.h"

namespace m2etis {
namespace pubsub {
namespace filter {

        template <typename EventType, typename AttributeType>
        class EqualsPredicateIndex : public PredicateIndex<EventType>  {
        public:
                EqualsPredicateIndex(AttributeName attribute_id, PredicateIdentifierFactory* predicate_identifier_factory) : PredicateIndex<EventType>(attribute_id, EQUALS, predicate_identifier_factory) {}

                // adds value of predicate to hashmap
                PredicateIdentifierFactory::PredicateID addPredicate(const EqualsAttributeFilter<EventType, AttributeType> * equals_attribute_filter) {
                        // first checking if identical predicate already exists => use same predicate id
                        if (predicate_id_to_attribute_value_.find(equals_attribute_filter->get_constants()[0]) != predicate_id_to_attribute_value_.end()) {
                                return predicate_id_to_attribute_value_[equals_attribute_filter->get_constants()[0]];
                        }
                        // no identical predicate exists, insert into hash map
                        PredicateIdentifierFactory::PredicateID new_predicate_id = this->predicate_identifier_factory_->createPredicateIdentifier();
                        predicate_id_to_attribute_value_.insert(std::pair<AttributeType, PredicateIdentifierFactory::PredicateID>(equals_attribute_filter->get_constants()[0], new_predicate_id));

                        return new_predicate_id;
                }

                virtual void removePredicate(std::vector<bool>::size_type predicate_id) override {
                        this->predicate_identifier_factory_->freeID(predicate_id);

                        for (auto attributeValue_predicateID_pair_iter = predicate_id_to_attribute_value_.begin(); attributeValue_predicateID_pair_iter != predicate_id_to_attribute_value_.end(); ++attributeValue_predicateID_pair_iter) {
                                if (attributeValue_predicateID_pair_iter->second == predicate_id) {
                                        predicate_id_to_attribute_value_.erase(attributeValue_predicateID_pair_iter);
                                }
                        }
                }

                // determines the fulfilled predicates which are in this index
                // And sets the "bit" in the fulfilled predicate vector to true
                virtual void determineMatchingPredicates(const EventType & event, std::vector<bool> & fulfilled_predicate_vector) override {
                        // all predicates are fulfilled with the constant having the same value (which all have the same predicate id)
                        auto attribute_value_iterator = attributes_accessor_map.find(this->get_attribute_id());

                        if (attribute_value_iterator == attributes_accessor_map.end()) {
                                M2ETIS_THROW_API("EqualsPredicateIndex function determineMatchingPredicates", "Attribute not found in attribute map.");
                        }

                        fulfilled_predicate_vector[predicate_id_to_attribute_value_[(dynamic_cast<AttributeAccessor<EventType, AttributeType> *>(attribute_value_iterator->second.get()))->getAttributeValue(event)]] = true;
                }

                virtual ~EqualsPredicateIndex() {}

        private:
                // hashmap as index structure to determine matching predicates efficiently
                // matches a value to the predicate identifier:
                // identical indexes get assigned the same predicate identifier
                std::map<AttributeType, PredicateIdentifierFactory::PredicateID > predicate_id_to_attribute_value_;
        };

} /* namespace filter */
} /* namespace pubsub */
} /* namespace m2etis */

#endif /* __M2ETIS_PUBSUB_FILTER_GENERALBOOLEANALGEBRA_EQUALSPREDICATEINDEX_H__ */