extras/indexing/src/main/java/org/apache/rya/indexing/external/matching/QuerySegment.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.List;
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.evaluation.impl.ExternalSet;

/**
 * A QuerySegment represents a subset of a query to be compared to ExternalSets for
 * query matching. The QuerySegment is represented as a List, where the order of
 * the nodes in the list is determined by a Visitor as it traverses the Segment
 * from top down, visiting right children before left.
 *
 * @param <T> - The type of ExternalSet that will replace a subset of nodes in this segment.
 */
public interface QuerySegment<T extends ExternalSet> extends Cloneable{

    /**
     *
     * @return - an unordered view of the {@link QueryModelNode}s in the segment
     */
    public Set<QueryModelNode> getUnOrderedNodes();

    /**
     *
     * @return - an ordered view of the {@link QueryModelNode}s in the segment.
     */
    public List<QueryModelNode> getOrderedNodes();

    public Set<Filter> getFilters();

    /**
     *
     * @param segment
     *            - this method verifies whether the specified segment is
     *            contained in this segment
     * @return - true if contained and false otherwise
     */
    public boolean containsQuerySegment(QuerySegment<T> segment);

    /**
     * Sets List of {@link QueryModelNode}s representing this QuerySegment to
     * specified list
     *
     * @param nodes
     *            - nodes to set
     */
    public void setNodes(List<QueryModelNode> nodes);

    /**
     * @param nodeToReplace
     *            - QuerySegment representation of ExternalSet T to match with
     *            subset of this QuerySegment
     * @param set
     *            - ExternalSet to replace matching QuerySegment nodes if match
     *            occurs
     * @return - true if match occurs and false otherwise
     */
    public boolean replaceWithExternalSet(QuerySegment<T> nodeToReplace, T set);

    public TupleExprAndNodes getQuery();

}