extras/indexing/src/main/java/org/apache/rya/indexing/external/matching/AbstractQuerySegment.java

package org.apache.rya.indexing.external.matching;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.rya.indexing.external.matching.QueryNodesToTupleExpr.TupleExprAndNodes;
import org.eclipse.rdf4j.query.algebra.Filter;
import org.eclipse.rdf4j.query.algebra.QueryModelNode;
import org.eclipse.rdf4j.query.algebra.ValueExpr;
import org.eclipse.rdf4j.query.algebra.evaluation.impl.ExternalSet;

import com.google.common.base.Preconditions;
import com.google.common.collect.Maps;
import com.google.common.collect.Sets;

/**
 * This class provides implementations of methods common to implementations of
 * the {@link QuerySegment} interface.
 *
 */
public abstract class AbstractQuerySegment<T extends ExternalSet> implements QuerySegment<T>, Cloneable {

    protected List<QueryModelNode> orderedNodes = new ArrayList<>();
    protected Set<QueryModelNode> unorderedNodes = new HashSet<>();
    protected Map<ValueExpr, Filter> conditionMap = Maps.newHashMap();

    /**
     * Returns Set of nodes contained in the segment
     */
    @Override
    public Set<QueryModelNode> getUnOrderedNodes() {
        return Collections.unmodifiableSet(unorderedNodes);
    }

    /**
     * Returns a List of nodes contained in this segment, where order is
     * determined by the getJoinArgs method
     *
     * @param TupleExpr
     *            from top to bottom.
     */
    @Override
    public List<QueryModelNode> getOrderedNodes() {
        return Collections.unmodifiableList(orderedNodes);
    }

    /**
     * Allows nodes to be reordered using {@link ExternalSetMatcher} and set
     * 
     * @param nodes
     *            - reordering of orderedNodes
     */
    @Override
    public void setNodes(List<QueryModelNode> nodes) {
        Set<QueryModelNode> nodeSet = Sets.newHashSet(nodes);
        Preconditions.checkArgument(nodeSet.equals(unorderedNodes));
        orderedNodes = nodes;
        unorderedNodes = nodeSet;
    }

    /**
     * @param query
     *            - QuerySegment that this method checks for in this JoinSegment
     */
    @Override
    public boolean containsQuerySegment(QuerySegment<T> query) {
        return unorderedNodes.containsAll(query.getUnOrderedNodes());
    }

    /**
     * @return - a TupleExpr representing this JoinSegment
     */
    @Override
    public TupleExprAndNodes getQuery() {
        List<QueryModelNode> nodeCopy = new ArrayList<>();
        for (QueryModelNode q : orderedNodes) {
            if (!(q instanceof ValueExpr)) {
                nodeCopy.add(q.clone());
            }
        }
        QueryNodesToTupleExpr qnt = new QueryNodesToTupleExpr(nodeCopy, getFilters());
        return qnt.getTupleAndNodes();
    }

    @Override
    public Set<Filter> getFilters() {
        Collection<Filter> filters = conditionMap.values();
        Set<Filter> filterSet = new HashSet<>();
        for (Filter filter : filters) {
            filterSet.add(filter.clone());
        }

        return filterSet;

    }
    

}